Field of Science

Edible Stinkbugs

In recent years, there has been some discussion in certain circles about whether people in western cultures should become more accepting of the practice of entomophagy: that is, eating bugs. For the most part, insects do not play a big part in diets in the English-speaking world except indirectly. In other parts of the world, however, certain insects may be eaten with relish. One such insect is the edible stinkbug Encosternum delegorguei of southern Africa.

Edible stinkbug Encosternum delegorguei, from Dzerefos et al. (2013).


The edible stinkbug is a member of the family Tessaratomidae, one of a number of families in the stinkbug superfamily Pentatomoidea. Tessaratomids are mostly relatively large, flat-bodied stinkbugs, often with shining metallic coloration, found in warmer parts of the world. They are all plant-suckers; one species, the lychee stinkbug Tessaratoma javanica, is a significant pest of lychee crops while the bronze orange bug Musgraveia sulciventris is a pest of citrus trees in Australia. The edible stinkbug feeds on a range of tree species, belonging to a number of different flowering plant families such as Combretaceae, Fabaceae and Ebenaceae. Though widespread in southern Africa, their distribution seems to be patchy; only certain ethnicities have a tradition of stinkbug harvesting (Dzerefos et al. 2013).

Harvester collecting stinkbugs, copyright Cathy Dzerefos.


Edible stinkbugs are collected during winter (the dry season) when they aggregate in large protective clusters (up to football-sized) on particular trees. Like other stinkbugs, Encosternum delegorguei produce a foul-smelling defensive chemical from glands on the thorax. As well as smelling bad, this chemical can stain skin and may cause temporary blindness if it gets into eyes. Dzerefos et al. (2013) note that stinkbug harvesters informed them that exposure to the defensive chemical over several years could cause fingernail loss and wart growth. The chemical needs to be removed from the bugs before they are cooked for consumption because, as one harvester explained, "if you eat the unprepared one it will kill taste for a month".

Clusters of stinkbugs are collected live into bags which are then shaken to encourage the bugs to discharge their chemicals. Further processing could be done by two methods. Perhaps the more common method is to pinch off the head of each bug then squeeze out the contents of the thorax, after which the bugs are cooked immediately. However, the Bolobedu people (who collect stinkbugs more for commercial sale than for their own consumption) place the bugs into a bucket with a perforated base, then pour hot water over them and stir vigorously. The bugs discharge their glands into the water as the heat kills them. They are then rinsed off in cold water, then returned to hot water for about eight minutes, then spread out on bags on the ground to dry. Any bugs that had not fully discharged their glands before dying can be recognised by dark marks on the thorax and are discarded. Though slightly more involved than the waterless method, this process of preparation has the advantage that bugs can be stored for some time rather than having to be cooked immediately. Stinkbugs are usually cooked by braising in a frying pan with salt; they are supposed to have a spicy taste, like chili.

Basket of prepared stinkbugs, from here.


According to Dzerefos et al. (2013), many of the stinkbug harvesters they spoke to reported a decline in populations of the bugs in recent years. Potential reasons for the decline included drought and/or the felling of trees that would otherwise be used by the bugs as roosts. Could edible stinkbugs be more widely used commercially? Perhaps, but it should be noted that while some groups relish the bugs, their neighbours disdain the delicacy. Mind you, Bolobedu people apparently didn't eat the bugs themselves before the 1980s, only taking up harvesting them when co-workers in tea plantations taught them what a resource they had on their hands!

REFERENCE

Dzerefos, C. M., E. T. F. Witkowski & R. Toms. 2013. Comparative ethnoentomology of edible stinkbugs in southern Africa and sustainable management considerations. Journal of Ethnobiology and Ethnomedicine 9: 20.

Publication date of Bulletin de la Société Philomathique

I should say up front, this is going to be a pretty esoteric one. It's just that this is something I spent a fair chunk of a morning trying to work out, and I may as well put what I found up here in case someone else finds it useful.

A few weeks back I found myself, as one does, trying to sort out the exact publication date of early numbers of the Bulletin des Sciences, par la Societé Philomathique de Paris, which has been archived online at the Biodiversity Heritage Library. The Société Philomathique was an association of French scientists and polymaths from a wide range of disciplines founded in 1788. You can find the webpage for the current iteration of the Société here. In 1791, the Societé decided to circulate a bulletin of abstracts of their meetings, including summaries of papers and letters presented there.

The title page of the volume of the Bulletin available at the Biodiversity Heritage Library gives the dates of "Juillet 1791, a Ventôse, An 7", or July 1791 to February–March 1799, which is the dates of the meetings presented therein ("Ventôse, An 7" is a date in the Republican Calendar that was introduced for a period following the establishment of the French Republic in 1792). Citations I could initially find for individual notices in the Bulletin were all attributed to dates of the separate meetings that they were presented at (e.g. something presented at the May 1794 meeting would be cited as "1794"). But it was immediately obvious to me that the notices could not have been published at the times of the original meetings, at least not as they appeared in the volume reproduced, because abstracts from separate meetings would appear on the same page! Hence my search for information on the Bulletin's actual publication date: were notices for individual meetings issued separately at the time, or did they not actually appear in print until the subsequent publication (presumably in 1799 or even later) of the collected volume? I should note that some of the abstracts in the Bulletin included descriptions of new species, so the question of publication date could have further taxonomic implications.

A page from the collated Bulletin, showing how the last entry for the December 1792 meeting is followed immediately by the section for January 1793, without a page-break for originally separate issues to have been collected together.


Eventually, I was able to establish that separate Bulletin issues had indeed been released for each meeting (you can see reproductions of the uncollated originals at Gallica). However, there is a complication. Early issues of the Bulletin were written by hand, and distributed only to the members of the Société (about 18 people at the time). It was not until November 1792 that a printed version of the Bulletin began to be disseminated more widely. Now, the International Code of Zoological Nomenclature requires that any publication for taxonomic purposes produced before 1986 must "have been produced in an edition containing simultaneously obtainable copies by a method that assures...numerous identical and durable copies" (Article 8.1.3). A handwritten manuscript would not meet that requirement, so any zoological name appearing in those early bulletins would not count as published. They would not become established until the subsequent publication of the collated volume, which according to an introduction written by Jonathan Mandelbaum in 1977 for a bound collection of the original Bulletin issues (reproduced at Gallica here) happened in 1802.

Original first page of the Bulletin for January 1793. As well as the separation from the December entries, note that the first entry of the original version has been omitted from the collated version, and that the title's original spelling said 'Philomatique' rather than 'Philomathique'.


As an example of the sort of consequences that might arise from this, consider Odiellus spinosus, a widespread harvestman species found in western Europe. This species was very briefly described, as Phalangium spinosum, by Bosc in 1792 in one of the manuscript issues of the Bulletin de la Societé Philomatique (the February 1792 one, to be exact). This has uniformly been accepted as the publication date, but Bosc's species was not properly published until 1802. This might be a simple question of book-keeping, were it not that, in the meantime, Latreille (1798) had used the name 'Phalangium spinosum' for a quite different harvestman species, and described what is now known as 'Odiellus spinosus' under the name of 'Phalangium histrix'. So strict application of the law of priority means that the species in question should be known as Odiellus histrix.

Fortunately, in this case there may be some loopholes available to us. Latreille's names both have strict priority over Bosc's, but they may each count as nomina oblita ('forgotten names'). This is a provision in the ICZN that a name that has not been used as valid since before 1899 can be set aside in favour of a more widely recognised junior synonym if "the junior synonym or homonym has been used for a particular taxon, as its presumed valid name, in at least 25 works, published by at least 10 authors in the immediately preceding 50 years and encompassing a span of not less than 10 years" (ICZN Art. 23.9.1.2). Latreille's Phalangium spinosum was soon recognised as a synonym of an earlier name, and was last used as valid in 1802. Phalangium histrix (or derived combinations thereof) persisted in the literature for longer, but I haven't come across it being used as a separate species after 1876. The open question is whether Bosc's name has been used often enough to warrant automatic conservation. I suspect it would have (I haven't done a proper tally myself, but a search for 'Odiellus spinosus' on Google Scholar brings up about 130 results) but, if not, then an appeal to the ICZN would be required if we wanted to keep using the current name for the species.

Harden Up, Puffball!

Near my home back in Australia, there's a park where we walk the dog most days. During the summer, when Perth receives little rain, the grass in the park dries off and the ground becomes hard. In some particularly dry spots, ground cover is absent completely (there's a large bare patch that used to house a meat ant colony; the ants died off a few years back but the nest site has never been re-claimed by grass). As autumn approaches, cream-coloured lumps can be seen in these bare patches, pushing their way through cracks in the ground. The lumps eventually crack and split, turning to dust over the course of several weeks. These lumps are Pisolithus puffballs.

Mature Pisolithus 'arhizus' puffballs, copyright Paul Venter.


A long-established system in the classification of basidiomycete fungi (the class of fungi that includes most familiar mushroom-forming species) divided many of the species between two groups, the hymenomycetes and the gasteromycetes. Hymenomycetes (the name means 'membrane fungi') included the classic mushrooms, with spores produced on an exposed membrane on the open fruiting body (often underneath) from which they were expelled when mature. Gasteromycetes ('stomach fungi') were forms such as puffballs in which spore-producing structures were completely enclosed within a sealed fruiting body; these structures would break apart at maturity and only then would the fruiting body open up to release the freed spores. However, while the hymenomycete-gasteromycete division was certainly convenient, it was not entirely watertight. For instance, ink-cap mushrooms were clearly hymenomycetes going by their exposed membranes, but the way their fruiting bodies dissolved to release their spores was more than a little gasteromycete-like. When molecular phylogenetic studies came to be included in the mix, it became clear that the two groups were not phylogenetically distinct. Indeed, the usual poster-children for gasteromycetes, the Lycoperdaceae puffballs, have turned out to be close relatives to the most familiar of all hymenomycetes, the field mushroom Agaricus bisporus. 'Gasteromycetes' have evolved from 'hymenomycete' ancestors on several different occasions; a puffball is basically a mushroom that doesn't open.

When molecular studies came to examine Pisolithus and a number of related 'gasteromycete' taxa, they turned out to be related to the 'hymenomycete' boletes in the order Boletales. Boletes are spongy mushrooms in which the spore-producing section on the underside of the cap is divided into pores rather than gills. Some boletes are highly regarded for their edibility, if you can get to them before other animals and insects that find them equally tasty do (others, however, are toxic, so as always with mushroom-hunting you need to know what you're eating). A new lineage in the Boletales, the Sclerodermatineae, was recognised for Pisolithus and its relatives; this lineage includes some forms that would have been recognised in the past as gasteromycetes and some that would have been called hymenomycetes. As with other members of the Boletales, most if not all members of the Sclerodermatineae are ectomycorrhizal, forming close symbiotic associations with the roots of certain trees. In most cases, these associations are essential to the well-being of both members of the partnership as the two exchange nutrients.

Salmon gum mushroom Phlebopus marginatus, copyright Ian Sutton.


'Hymenomycete' genera of the sclerodermatines include Gyroporus, Boletinellus and Phlebopus. Members of these genera are more or less similar in overall appearance to other boletes, though Boletinellus has thin caps on which the stalk may be displaced to one side rather than central and the pores on the underside are less distinct. Gyroporus boletes may be characterised by features of the stalk, in which the centre has a fluffy section that dissolves over time to leave a hollow core. The fruiting bodies produced by species of Phlebopus can be absolutely massive: weights of up to 30 kg have been recorded for a single mushroom. Boletinellus and Phlebopus (which together form the Boletinellaceae) are remarkable in that their ectomycorrhizae are actually harmful to the trees with which they associate. Hyphae of Boletinellaceae form sheaths or crusts around the roots of trees that are not normally involved in ectomycorrhizal associations (ash in the case of Boletinellus merulioides, various trees such as citrus and coffee in the case of Phlebopus species) that provide a home for aphids or mealybugs. The bugs have a sheltered place to live, and the fungus gains nutrients excreted by the bugs as they feed on the tree roots.

Phylogenetic analyses indicate that the Boletinellaceae are the sister group to other Sclerodermatineae (Wilson et al. 2012) but whether the 'gasteromycete' sclerodermatines are monophyletic to Gyroporus or not is more of an open question. Gasteroid sclerodermatines include the earthballs Scleroderma and the horse dung fungus Pisolithus. Members of these genera have hard, puffball-like fruiting bodies; in the case of Pisolithus, these fruiting bodies are so hard that they may sometimes be seen forcing their way through road asphalt or concrete. Both Scleroderma and Pisolithus have been widely used in inoculating soil for forestry and revegetation, in part because they form ectomycorrhizal associations with a wide variety of tree species. However, more recent studies have suggested that some of this apparent egalitarianism may be due to confusion between cryptic species; individual strains of the two genera may be more host-selective than previously recognised (Watling 2006). Inoculation with the wrong strain might then lead to tree growth not being helped, or even being hindered. Another example of the practical consequences of poor taxonomy!

Barometer earthstars Astraeus hygrometricus, copyright Richard Sullivan.


Similar taxonomic questions surround the barometer earthstars of the genus Astraeus, long recognised as a single cosmopolitan species A. hygrometricus but probably a complex of more localised species. Earthstars have a double-layered covering (peridium) to the fruiting body; the outer layer of the peridium is leathery and splits open when mature into several pointed rays, hence the fungus' vernacular name. A double-layered peridium is also found in the fruiting bodies of another sclerodermatine genus, Calostoma, but in this case the outer layer is gelatinous. The inner layer of the peridium is brightly coloured, and the appearance of the Calostoma fruiting body as the outer layer breaks open has led to the vernacular name of 'prettymouth'.

Mature prettymouth Calostoma cinnabarina, copyright Dan Molter.


Other members of the Sclerodermatineae are less well known. Diplocystis wrightii is a sclerodermatine known from various locations around the Caribbean that produces clusters of small globular fruiting bodies arising from a basal stroma (hyphal mass). As the upper surface of the peridium becomes dry and papery, it splits apart to turn the fruiting body into an open cup. A similar arrangement of clustered, cup-shaped fruiting bodies is known in a fungus species found in Burmese amber, Palaeogaster micromorpha (Poinar et al. 2014), though structural differences argue against a direct relationship between the two. Finally, there are many other unusual 'gasteromycetes' whose affinities remain uncertain; future studies may yet assign further exemplars to the spectrum of sclerodermatine diversity.

Preserved Palaeogaster micromorpha in Burmese amber, from Poinar et al. (2014).


REFERENCES

Poinar, G. O., Jr, D. da Silva Alfredo & I. G. Baseia. 2014. A gasteroid fungus, Palaeogaster micromorpha gen. & sp. nov. (Boletales) in Cretaceous Myanmar amber. Journal of the Botanical Research Institute of Texas 8 (1): 139–143.

Watling, R. 2006. The sclerodermatoid fungi. Mycoscience 47: 18–24.

Wilson, A. W., M. Binder & D. S. Hibbett. 2012. Diversity and evolution of ectomycorrhizal host associations in the Sclerodermatineae (Boletales, Basidiomycota). New Phytologist 194: 1079–1095.

Fusulinoids: Complex Forams of the Late Palaeozoic

Among the most characteristic fossils of the latter part of the Palaeozoic are the group of Foraminifera known as the fusulinoids. These forams, known from around the middle of the Carboniferous to the end of the Permian, can be extremely abundant. Indeed, I get the impression that some fossil deposits are pretty much made of fusulinoids. Fusulinoids did not merely thrive in their environment; they were the environment.

Limestone block dominated by fusulinids, copyright James St John. Field of view is about 3.9 cm across.


Fusulinoids are distinguished from other forams by their test composition, built from minute granules of calcite, and complex internal structure. Externally, fusulinoids (defined here to exclude their forerunners, the endothyroids) were fairly conservative, with a planispiral, usually involute test (that is, each successive whorl covers the last). The last whorl ended on a transverse wall without a defined aperture; instead, the only connection between the interior and exterior of the test was by a series of pores in said wall. Early forms were disc-shaped; later species could be more globular or fusiform. Some of the later fusulinoids also reached gigantic sizes by single-celled organism standards: whereas the earliest fusulinoids were only a fraction of a millimetre across, the late Permian Polydiexodina could be up to six centimetres along their longest axis (Loeblich & Tappan 1964). Internally, fusulinoids had an incredibly complicated and varied structure which I'm not going to go into too much detail about here, primarily because I barely understand a word of it myself. Any description of fusulinoid morphology quickly devolves into madly throwing about terms like chomata, parachomata, spirotheca, tectorium, and the like, and your humble narrator feeling the need to go look at something else.

Cutaway diagram of a fusulinid, showing an example of internal structure, from here.


I have to go into some detail, though, because some features of the fusulinoid wall structure may explain their success. The ancestral state for the fusulinoid test wall involved a thin layer of solid calcite, the tectum. In most species, the inside of the tectum was coated with a thicker, less dense layer. As the test wall becomes more derived, this inner layer becomes more or less translucent, or pierced by tubular alveoli to produce a honeycomb-like appearance. It has been suggested that these modifications may have been adaptations to accomodating symbiotic microalgae, striking a balance between maintaining the protective test and allowing optimal transmission of light. Microalgal associations with fusulinoids may be corroborated by the discovery of minute fossils of probable planktonic relationships such as Ovummuridae preserved within fusulinoid tests (Vachard et al. 2004).

Ecologically, fusulinoids were restricted to off-shore marine habitats, being mostly found preserved in limestones and calcareous shales. They are absent from deposits that would have been formed in brackish water, and while they may be found in sandstones it is debatable whether such occurrences represent life associations or post-mortem transport (Loeblich & Tappan 1964). Fusulinoids would therefore have been ecologically similar to the inhabitants of modern-day photic zone coral reefs, another reflection of their probable co-dependence with photosynthetic microalgae. However, as successful as the advanced fusulinoids were in their time, they did not make it past the massive extinction event at the end of the Permian. This was not the end of giant and complex forams entirely—indeed, some later forms such as the alveolinids would evolve morphologies very similar to those of fusulinoids—but it was the end of these particular giant forams.

REFERENCES

Loeblich, A. R., Jr & H. Tappan. 1964. Treatise on Invertebrate Paleontology pt C. Protista 2. Sarcodina, chiefly "thecamoebians" and Foraminiferida vol. 1. The Geological Society of America and The University of Kansas Press.

Vachard, D., A. Munnecke & T. Servais. 2004. New SEM observations of keriothecal walls: implications for the evolution of Fusulinida. Journal of Foraminiferal Research 34 (3): 232–242.

Hyopsodontids: Little Slinkers of the Palaeogene

The oft-repeated quote about mammalian palaeontology is that it tends to be focused on "the tooth, the whole tooth, and nothing but the tooth". This is primarily the result of pragmatic constraints: because they are much harder than the other bones of the mammalian skeleton, teeth are much more likely to be preserved in the fossil record. There are a great many fossil mammals for which the teeth remain pretty much the only part of the animal known. However, there is no question that this focus tends to limit our understanding of mammalian evolution. On the one hand, the complex morphology of many mammalian teeth means that they provide a wealth of characters for analysis. On the other, the morphology of teeth is heavily influenced by their bearer's diet and lifestyle, meaning that phylogenetically informative features are probably outweighed by the products of ecological convergence.

Reconstruction of Hyopsodus from Savage & Long (1978), via here.


All of which is pretty important background to keep in mind for any discussion of the Hyopsodontidae, a group of small (mostly rat- or weasel-sized) mammals recognised from the Palaeogene, the early part (Palaeocene and Eocene epochs) of the Caenozoic era. Hyopsodontids are generally assigned to the 'Condylarthra', a group of mammals that has long been recognised as one of the classic examples of a 'wastebasket taxon'. Condylarths were originally united as primitive relatives of the ungulates, the hoofed mammals. However, the individual condylarth families themselves have not got much in common otherwise, and (particularly with the current acceptance that 'ungulates' are probably not a monophyletic group) it is hard to come up with a definition for 'condylarths' that amounts to much more than 'medium-sized, unspecialised Palaeogene placentals'.

The hyopsodontids have been recognised as one of the longest-lived groups of 'condylarths', with assigned members extending from close to the start of the Palaeocene right up to near the end of the Eocene. Here again, though, we come up against the question of definition. The majority of taxa that have been aligned with the hyopsodontids are among those known only from teeth. Features of the hyopsodontid dentition include fairly simple incisors and premolars, small canines, and molars that are more or less bunodont (that is, the cusps are rounded or conical and clearly separate from each other rather than being connected by lophs). The problem is that these are all primitive, unspecialised features. Hyopsodontids are therefore defined more by their lack of alternate specialisations than anything positive, making them something of a wastebasket within a wastebasket.

Until recently, the only hyopsodontid known from much in the way of postcranial material was the type genus Hyopsodus, a number of species of which are known from an extended period of the Eocene. Indeed, Hyopsodus was one of the most abundant mammalian genera of its time, accounting for over a quarter of mammalian remains in a number of deposits where it is found (Rose 2006). These remains combine to give a picture of Hyopsodus as a long, low-bodied animal that has been compared in its proportions to a dachshund, a weasel, or a prairie dog. Hyopsodus would have been a ground-hugging slinker of an animal, build for concealment rather than speed. Short claws on the forelegs may be consistent with a certain degree of digging ability, whether in search of buried tubers or to scrape shallow burrows. Overall, Hyopsodus was probably a generalist, able to make a living wherever it may find itself: the real rat of the Eocene.

It was only relatively recently that Penkrot et al. (2008) provided further descriptions of limb-bone material from two other genera associated with the hyopsodontids, Apheliscus and Haplomylus. And despite the dental similarities between these genera and Hyopsodus, their postcranial anatomy indicates a quite different animal. Though small, the apheliscines were relatively long-legged, speedy runners: sprinters rather than slinkers. Penkrot et al. interpreted the apheliscines as relatives of the modern elephant shrews of Africa; whether or not there was a valid phylogenetic connection, the two would have certainly been ecologically similar.

Both Hyopsodus and Apheliscus were included in the broad-scale analysis of early placental phylogeny by Halliday et al. (2017). The results of the analysis corroborate the implications of the postcranial anatomy: despite dental similarities, the 'hyopsodontids' in the broad sense are not a monophyletic group. Over a dozen other genera are known of candidate hyopsodontids, but so long as they are known only from dental characters their true position remains uncertain. Without postcranial data, it seems, we can't handle the tooth.

REFERENCES

Halliday, T. J. D., P. Upchurch & A. Goswami. 2017. Resolving the relationships of Paleocene placental mammals. Biological Reviews 92 (1): 521–550.

Penkrot, T. A., S. P. Zack, K. D. Rose & J. I. Bloch. 2008. Postcranial morphology of Apheliscus and Haplomylus (Condylarthra, Apheliscidae): evidence for a Paleocene Holarctic origin of Macroscelidea. In: Sargis, E. J., & M. Dagosto (eds) Mammalian Evolutionary Morphology: A Tribute to Frederick S. Szalay pp. 73–106. Springer.

Rose, K. D. 2006. The Beginning of the Age of Mammals. JHU Press.

Platyschismatinae

Platyschisma helicoides, from Knight et al. (1960).


In an earlier post on this site, I commented on some of the various ways that gastropods deal with the fact that their development tends to put their anus uncomfortably close to their mouth. A common solution is the development of a sinus or slit in the shell that provides spaces for the anus to be moved backwards.

One of the major gastropod groups exhibiting such a feature is known as the Pleurotomarioidea. In the modern fauna, pleurotomarioids are not hugely abundant, with living species restricted to deep waters. However, they were one of the dominant gastropod groups back in the Palaeozoic when they were represented by a number of families. One Palaeozoic pleurotomarioid group is the Platyschismatinae, known from the Lower Ordovician to the Middle Permian (Knight et al. 1960). Platyschismatines went with the sinus option, with a sinus present at or above the midpoint on the outer edge of the shell opening. Knight et al. (1960) included five genera in the Platyschismatinae. The type genus, Platyschisma, has a slightly flattened spiral and a relatively thin shell. Some of the other platyschismatines were also relatively flat.

REFERENCE

Knight, J. B., L. R. Cox, A. M. Keen, R. L. Batten, E. L. Yochelson & R. Robertson. 1960. Gastropoda: systematic descriptions. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt I. Mollusca 1: Mollusca—General Features, Scaphopoda, Amphineura, Monoplacophora, Gastropoda—General Features, Archaeogastropoda and some (mainly Paleozoic) Caenogastropoda and Opisthobranchia pp. I169-I331. Geological Society of America, and University of Kansas Press.

Jewels among Beetles

There are many contenders for the title of most stunning-looking insect but there is no question that the jewel beetles have a place among the line-up. Some of these brilliantly coloured insects look as if they could have been sculpted from gleaming metal:

Buprestis niponica, copyright Kohichiro Yoshida.


Buprestis is a genus of jewel beetles found in the Holarctic region, with the greater diversity around the Mediterranean and North America. Somewhere between forty and eighty species are recognised, depending on whether the closely related genera Cypriacis and Yamina are regarded as distinct or not. Species of Buprestis come in a variety of colours, with green, blue or black backgrounds often patterned with yellow or red.

Female Buprestis octoguttata ovipositing, copyright Christian Fischer.


Despite their attractive appearance, jewel beetles are not always welcome. They spend the larval part of their life cycle burrowing into wood so some are known for damaging timbers. The preferred hosts of most Buprestis species, where known, appear to be conifers such as pine, spruce and larch. They primarily attack dead and dying wood, and females of some species are known for searching the trunks of trees following fires to find where protective bark has cracked open (some jewel beetle species in other genera are commonly known as 'fire beetles' in reference to this habit). Buprestis larvae have been claimed to live for extraordinarily long periods. Mature beetles have been observed emerging from furniture and the like multiple decades after the original tree was felled, leading to claims of larval life spans of up to 51 years! It almost goes without saying that such inferences have attracted their share of scepticism, with detractors suggesting the possibility of eggs being laid after the wood was already worked. It is true that the low nutritious value of dry wood might be expected to lead to slow development, but how slow are you willing to believe?

Hairy-Winged Barklice

Forewing and fore tibia of Siniamphipsocus fusconervosus, from Mockford (2003). Scale bar for the femur = 0.1 mm.


For my next semi-random post, I drew Siniamphipsocus, a genus of more than twenty species of barklice known from eastern Asia. Most of these species were described by China by the almost ludicrously prolific psocopterologist Li Fasheng who over the course of his career has described close to 1000 psocopteran species—nearly a fifth of the world's barklouse fauna. It should be noted, though, that this productivity has not entirely come without criticism: for instance, in the case of the Siniamphipsocus species, most if not all are known from a single sex with some described from males and others from females (Li 2002).

Siniamphipsocus is a genus of the Amphipsocidae, a family of barklice most easily recognised by their wings which have a double row of setae along each of the veins. Amphipsocids can be relatively large as barklice go: the largest Siniamphipsocus species, S. aureus, has a body length of four millimetres, with the forewings being up to 6.75 millimetres long. Features distinguishing Siniamphipsocus from other amphipsocids include the absence of the brush of hairs present at the base of the hind wing in many other species, the absence of a spur vein in the rear of the forewing pterostigma, and the presence of a row of minute spines along the fore femur (Li 2002). Distinguishing the individual species of the genus requires fine attention to details such the patterns of markings on the face, the proportions of the wing veins, and details of the genitalia.

REFERENCES

Li F. 2002. Psocoptera of China (2 vols). Science Press: Beijing.

Mockford, E. L. 2003. New species and records of Psocoptera from the Kuril Islands. Deutsche Entomologische Zeitschrift 50 (2): 191–230.

Sordariomycetidae: Soil Fungi A-Plenty

I'm pretty sure I've commented before that, although most of us tend to associate the word 'fungi' with mushrooms and other eye-catching fruiting bodies, the vast majority of fungal diversity is minute and tends to go unnoticed. Nevertheless, despite their obscurity, many of these microfungi are crucial to our own continued existence. These are the decomposers, the organisms that break down fallen plant matter and animal wastes in their own search for nourishment and so contribute to the release of locked-up nutrients back into the environmental cycle.

Neurospora growing on sugar cane waste, from here.


The group of fungi that I drew for today's post, the Sordariomycetidae, is primarily made up of these minute decomposers. Sordariomycetids have already made an appearance here at Catalogue of Organisms, in a post from ten years ago on black mildews. Depending on how broadly the group is circumscribed, the Diaporthales could also be included. Due to a simple morphology that provides few distinct characters, the Sordariomycetidae are primarily defined on the basis of molecular phylogenies. The difficulty of classifying microfungi by morphology alone is underlined by cases where species previously classified within the same genus have proven to belong to entirely distinct fungal lineages.

In general, the vegetative body of most Sordariomycetidae consists of little more than disassociated hyphae embedded in their substrate, with the only distinct structures being the reproductive fruiting bodies. These are perithecia: that is, globular or flask-shaped fruiting bodies with a single small opening or ostiole at the top through which the mature spores are released. In some cases, the internal structure of the mature perithecium will simply dissolve, freeing the spores to escape through the ostiole in the manner of a miniature puffball. In others, the spores become entangled in a long strand or seta that is then extruded through the ostiole like toothpaste being squeezed out of a tube.

Perithecium of Chaetomium extruding spore-bearing setae, from here.


Sordariomycetids are found in almost every habitat imaginable: as well as soil- and dung-dwelling forms, they may also be found in aquatic and even marine habitats. Perhaps the best-known sordariomycetid is Neurospora crassa, red bread mould, which is widely used in laboratories as a model organism for genetic research. Indeed, it was investigations into N. crassa in the 1950s that first led to the proposal of the 'one gene, one enzyme' model that became a cornerstone of molecular genetics.

A Western Rockweed

Rockweed Silvetia compressa, from here.


Silvetia compressa is a species of brown alga found on shorelines on the western coast of North America, from British Columbia to Baja California. It is a member of the wrack family Fucaceae that I covered in an earlier post. Silvetia compressa is found in midtidal habitats, generally higher up on the shoreline than other large seaweeds. Individual thalli can reach a maximum length of about three feet (90 cm) but are often smaller. This is a slow-growing species, so patches of Silvetia are slow to recover from damage due to trampling and other disturbance. Please try to avoid walking on the rockweed!

Thalli of Silvetia compressa are composed of thin strands a few millinetres in width with irregular, dichotomous branching. Strands of the thalli lack a midrib (distinguishing them from some other Fucaceae species found in the same area). The width of the strands and regularity of the branching varies with environmental conditions: for instance, individuals growing in locations with stronger wave action have more robust strands that branch more frequently. As with other Fucaceae, the reproductive structures a produced on swollen branch tips called receptacles, but these receptacles do not become inflated with gases and buoyant like those of other species. The exact size and shape of the receptacles is, again, variable.

In many older references, Silvetia compressa may be referred to as Pelvetia fastigiata. The supposed species 'Fucodium compressum' and 'F. fastigiatum' were originally distinguished on the basis that the latter was smaller than the former with more fastigiate branches (that is, the branches remained subparallel). As indicated above, these characters represent the effects of environmental conditions, not fixed differences (Silva 1996). They were eventually included in the genus Pelvetia, together with the Atlantic species P. canaliculata, on the basis of the thalli without a midrib, and the production of just two eggs from each oogonium in the receptacles. However, later analyses supported the separation of the Atlantic and Pacific species of Pelvetia. Not only did they not form a clade in molecular analyses, the eggs in the oogonia were separated by a horizontal division in the Atlantic species but a longitudinal or oblique division in the Pacific species (Silva et al. 2004). As such, the Pacific Pelvetia were transferred into a new genus Silvetia.

Further taxonomic complications involved subspecific variation in Silvetia compressa. A distinctive form of 'Pelvetia fastigiata' found at Pebble Beach in California's Monterey Bay, with smaller, finer thalli and more abundant, regular branching, was labelled as a separate forma gracilis. Similar individuals were also found on the islands off California's coast. However, when Silva (1996) examined the original type specimen of P. fastigiata, he discovered that it was an individual of this 'gracilis' form, not the more typical larger form. Later, Silva et al. (2004) examined genetic variation within the Silvetia compressa of California and Baja California. They found that the individuals of the offshore islands were indeed genetically distinct from continental individuals. As well as the differences in growth habit, there was also some difference in receptacle shape: the continental form had receptacles that tended to be linear and pointed whereas those of the island form were ellipsoidal and blunt. However, the island form still could not be labelled with either of the 'fastigiata' or 'gracilis' monikers, as individuals from the type locality of Pebble Beach did not align genetically with insular individuals but with other continental forms. As such, yet another name had to be coined for the insular form which now goes by the name of Silvetia compressa ssp. deliquescens. Let's see if it sticks this time.

REFERENCES

Silva, P. C. 1996. California seaweeds collected by the Malaspina expedition, especially Pelvetia (Fucales, Phaeophyceae). Madroño 43 (3): 345–354.

Silva, P. C., F. F. Pedroche, M. E. Chacana, R. Aguilar-Rosa, L. E. Aguilar-Rosa & J. Raum. 2004. Geographic correlation of morphological and molecular variation in Silvetia compressa (Fucaceae, Fucales, Phaeophyceae). Phycologia 43 (2): 204–214.

The Millenium Post

Apparently, this is the 1000th post to appear at Catalogue of Organisms. When I first started this site, over ten years ago, I don't know if I had any idea when, if ever, I would reach this point and where I would be when it happened. I probably imagined I would be thinner.

I want to thank everyone that has followed Catalogue of Organisms over the years. I particularly want to thank those readers who have supported me on Patreon: Paul Selden, Sebastian Marquez, Rob Partington, William Holz. Your contributions have meant a lot to me. Apropos of that, some news: some of my readers may recall that my employment status has been a little up in the air for a large chunk of the last couple of years (though I was able to find casual positions for some of that time). A few months ago, though, an opportunity came up to work on a project looking at insect diversity in mangroves in Hong Kong. Though it means being away from my home, my partner and my dog for a couple of years, the opportunity was too good to pass up and for the next little while I'll be based in the city of the Fragrant Harbour (especially around the port district in high summer).

So on to the next 1000 posts, then? We'll just have to see. Certainly I'm not putting stuff up here as frequently as I did in the past, when I was a carefree post-graduate student. There have been times when I've wondered if I should keep going. People far more talented and perspicacious than I have had a great deal to say elsewhere about the apparent decline of science blogging as a format, and it certainly doesn't seem to attract the audience it once did. Nevertheless, I think I'll be going for a while yet. I've noted before that this blog functions as my own means and motivation for investigating things that I might find interesting, and there's certainly no shortage of things left to investigate. And as for the health of science blogging overall: a glance to the sidebar to the right of this page reminds me that there's still a lot out there worth following. There's Deep Sea News, there's Small Things Considered, Bug Eric, Tetrapod Zoology, Letters from Gondwana, Synapsida, Beetles in the Bush, and so many more. If you don't already know these sites, check them out!

For my part, the main indicator I see as to whether people are reading anything here is when people leave comments. A big thank you again to those who have contributed over the years. I'm needy, and need validation... And in that light, I'd like to specially ask my readers to comment on their general feelings (if any) about Catalogue of Organisms. Has there been anything you've particularly liked about the site over the years? Any favourite posts? Anything you'd like to see going forward? And once again...

The Shrinking World of Bandicoots

A bandicoot is a very disagreeable animal to clean, therefore it should be done as soon after killing as possible, and then the flesh can be left in strong vinegar and water for a few hours before dressing. Sweet potatoes and onion make a good stuffing for bandicoot, which is good either boiled or baked.--Mrs Lance Rawson, Australian Enquiry Book of Household and General Information.


Golden bandicoots Isoodon auratus barrowensis, copyright Kathie Atkinson.


Back when I used to work on Barrow Island in the north-west of Australia, one of the more noticeable animals to be seen around the place was the golden bandicoot Isoodon auratus. In the evenings, the place seemed to absolutely swarm with them. About the size of a guinea pig, with no tails to speak of (bandicoots are actually born with fairly long tails but tend to lose them in the course of their quite vicious fights with one another; few if any individuals reach maturity with their tails intact), there was no question about their qualifications when it came to cuteness.

Bandicoots are a group of twenty-odd species of marsupial found in Australia and New Guinea (one species, the Seram bandicoot Rhynchomeles prattorum, was described from montane forest on the Indonesian island of Seram to the west of New Guinea). Most are primarily insectivorous, but they also eat varying amounts of small vertebrates and plant matter such as bulbs and fruit. The largest bandicoot, the giant bandicoot Peroryctes broadbenti, has been recorded to reach close to five kilograms in weight. The smallest, the Papuan bandicoot Microperoryctes papuensis, weighs less than 200 grams. I suspect many people in Australia assume that the name 'bandicoot' comes from one of the the Aboriginal languages, but it is in fact Indian (specifically Telugu) in origin. The original bandicoot Bandicota indica is a large rat that is widespread in southern Asia and Australian bandicoots were named for their resemblance to this species. Personally, I have maintained in the past that Australian bandicoots look more like rats than rats do: with their relatively long snouts, bandicoots bear a distinct resemblance to the sort of cartoon figure that comes to most people's minds when they hear the word 'rat'.

New Guinea spiny bandicoot Echymipera kalubu, copyright Michael Pennay.


Bandicoots are highly distinctive from all other marsupials in appearance. Their hind legs are noticeably longer than their forelegs and more or less specialised for cursorial locomotion (especially so in one example that I'll get to shortly). The fourth and fifth toes of the hind foot are much larger than the other three; the first toe in particular is reduced to a non-functional stub. The second and third toes of the hind foot, as in diprotodontian marsupials such as kangaroos and possums, are externally joined together with the two claws at the end forming a comb that is used in grooming more than in locomotion. The fore feet, in contrast, are mostly functionally three-fingered (with the first and fifth fingers reduced) and adapted for digging with the claws large and flat.

Many bandicoots are rapid reproducers with their gestation periods among the shortest of any mammal, less than two weeks between fertilisation and birth. Bandicoots also have the most developed placentas of any marsupial group (yes, most marsupials do have a placenta, albeit a much simpler one than found in placental mammals); it is presumably because of this that, despite their short gestation, bandicoot young are born at a more advanced stage of development than those of some other marsupials. When the young are born, they initially remain attached to their mother via the umbilical cord; this latter does not become detached and the placenta ejected until after the joey is firmly attached to a teat in the rearward-opening pouch. The young remain in the pouch for about two months and grow rapidly; they may reach full sexual maturity at the age of only three months. As a result, bandicoot populations may increase rapidly if conditions permit.

Greater bilby Macrotis lagotis, copyright Bernard Dupont.


In terms of classification, there is a general consensus that Recent bandicoots can be divided between four groups though there has been some disagreement about exactly these groups are interrelated (and hence exactly how they should be ranked). The most diverse, but probably also the least studied, group of modern bandicoots are the rainforest bandicoots of the Peroryctidae or Peroryctinae. These are about a dozen species found mostly in New Guinea with the aforementioned Rhynchomeles prattorum on Seram and the the long-nosed spiny bandicoot Echymipera rufescens extending its range to the northern tip of Queensland. Most of continental Australia is home to the dry-country bandicoots of the Peramelidae sensu stricto or Peramelinae, of which there are six Recent species (one of these, the northern brown bandicoot Isoodon macrourus, is also found in southern New Guinea). Peramelids tend to have shorter snouts and flatter skulls than peroryctids. The other two groups are both very small and also native to arid regions of Australia. Two Recent species are known of the genus Macrotis, the bilbies, though one of these is extinct and the other is endangered. Bilbies are larger than most other bandicoots, with long ears (hence their alternative vernacular name of 'rabbit-bandicoots') and a long, silky-haired tail.

Gerard Krefft's 1857 illustration of the pig-footed bandicoot Chaeropus ecaudatus, from here.


The final representative of the Recent bandicoots is unquestionably the weirdest of them all. Unfortunately, it is also now extinct, last recorded some time about the middle of the 20th Century, a fact that cannot be called anything less than a fucking tragedy. The pig-footed bandicoot Chaeropus ecaudatus was the most cursorial of all bandicoots. Its forelegs, rather than being adapted for digging as in other bandicoots, had only two functional toes on which the claws were modified into hooves. The hind legs went a step further and had only a single functional toe (raising the question of how this animal groomed itself without the aforementioned claw-comb of other bandicoots Edit: That was a bit of a blonde moment; a second look at the Krefft illustration above shows that the comb is definitely there). The most extensive observations of its habits seem to have been made by Gerard Krefft (1866) who kept a pair alive for about six weeks in 1857 on a trip to the Murray-Darling region before killing them to provide specimens because, you know, 19th-Century naturalist. Krefft recorded that his bandicoots subsisted primarily on plant foods such as lettuce, grass and roots, refusing all meat offered to them (Krefft also refers to providing grasshoppers for them but his account is unclear about whether they were ever eaten). A herbivorous diet was also indicated by the animals' droppings, which where dry and similar to a sheep's. The bandicoots constructed a covered nest from grass and leaves in the tin enclosure in which Krefft kept them in which they sheltered during the day, only becoming active after nightfall. Krefft notes that he acquired "about eight" specimens of pig-footed bandicoot during his six-month camp, admitting that some met a stickier end than others: "They are very good eating, and I am sorry to confess that my appetite more than once over-ruled my love for science; but 24 hours upon "pig-face" (mesembryanthemum) will dampen the ardour of any naturalist". Krefft also noted that several of the specimens found were female, and that despite being provided with eight teats the females never carried more than two joeys. A particularly interesting detail was that the fourth toe of the joeys' fore foot, rather than being reduced as in the adults, remained large so that the feet resembled those of other bandicoots. Presumably this was so that the fore-claws could still be used to allow the newborn joeys to climb from the birth canal to the pouch.

Krefft also noted that the pig-footed bandicoot was already declining in abundance, blaming its increased rarity on competition with introduced grazing livestock. Sadly, changing habitats and introduced predators have caused other bandicoot species to also become endangered since Krefft's time. Please, don't let them go the way of the pig-footed bandicoot.

REFERENCES

Gordon, G., & a. J. Hulbert. 1989. Peramelidae. In: Fauna of Australia vol. 1B. Mammalia. Australian Biological Resources Study: Canberra.

Krefft, G. 1866. On the vertebrated animals of the lower Murray and Darling, their habits, economy, and geographical distribution. Transactions of the Philosophical Society of New South Wales 1862–1865: 1–33.

A Second Look at Scallops

In a post that appeared at this site over eight years ago, I described some of the distinctive features of the Pectinoidea, the group of bivalves commonly known as scallops. It's time to look in a bit more detail at some of the points mentioned in that post.

Fossil of Pernopecten, the earliest scallop genus, from ammonit.ru.


Pectinoidea, in the sense recognised by Waller (2006), first appear in the fossil record way back in the late Devonian. They were probably derived from earlier members of the Aviculopectinoidea, an extinct group of bivalves that closely resemble scallops in their overall appearance and were included in the Pectinoidea by many earlier authors (such as in the 1969 Treatise on Invertebrate Paleontology volume on bivalves). However, the shell ligament of aviculopectinoids was reinforced by aragonite fibres (a primitive feature for bivalves) rather than having the specialised rubbery core found in pectinoids. As such, aviculopectinoids would have lacked the swimming abilities of true scallops. The Palaeozoic pectinoids belong to a single genus, Pernopecten, that possesses a number of features such as details of the shell crystalline structure that indicate a position outside the pectinoid crown group. In the early Triassic, Pernopecten begat the family Entolioididae that includes the ancestors of living pectinoids.

As mentioned in the previous post, four pectinoid families survive to the present day: the Pectinidae, Propeamussiidae, Entoliidae and Spondylidae. The first three families diverged in the early Triassic. Spondylids (usually classified in a single genus, Spondylus) were not to appear until the mid-Jurassic and Waller (2006) argued for their derivation from within the Pectinidae. The Pectinidae are otherwise distinguished from other pectinoids by a structure called the ctenolium. This is a row of teeth that develops on the shell in the gap between the disc and one of the auricles (the triangular 'wings' at the top of the shell). During the earlier part of the scallop's life, when it lives attached to the ocean bottom by a byssus (what in mussels we call the 'beard'), the ctenolium functions to hold the byssus threads in place and help stop the shell from twisting. In those pectinid species that lack a byssus in the latter part of their life, the ctenolium may end up getting overgrown by the expanding shell and disappearing, but all pectinids (ignoring the aforementioned Spondylus question) have a ctenolium for at least part of their life.

The propeamussiid Cyclopecten secundus, copyright Museum of New Zealand Te Papa Tongarewa.


The Pectinidae is the largest scallop family in the present day, followed by the Propeamussiidae. The Entoliidae were diverse during the Mesozoic but declined dramatically after the end of the Cretaceous (I'm not clear whether or not their decline was a direct part of the end-Cretaceous mass extinction). Indeed, entoliids are completely unknown from the fossil record between the Palaeocene and the late Pleistocene; like the tuatara, it might be that the post-Mesozoic survival of entoliids could have gone completely unrecognised were it not for the single surviving relictual genus.

In the earlier post, I implied that propeamussiids lack the eyes and guard tentacles of other pectinids; it turns out that this was a mistake on my part. Many propeamussiids found in the deep sea do indeed lack these features but they are present in shallow-water propeamussiids. It appears that these features are ancestrally common to all crown-group pectinoids but have been lost as an adaptation to life below the photic zone. The anatomy and lifestyle of many propeamussiids remains poorly known but those species that have been investigated have simplified gills compared to pectinids. The filaments of the gills are free rather than being connected by ciliary junctions. The lips of the mantle are also simplified, lacking the complex lobes found in pectinids. These features may be related to the carnivorous diet of many propeamussiids that feed on zooplankton rather than smaller phytoplankton and organic particles.

REFERENCE

Waller, T. R. 2006. Phylogeny of families in the Pectinoidea (Mollusca: Bivalvia): importance of the fossil record. Zoological Journal of the Linnean Society 148 (3): 313–342.

Trichosternus

Trichosternus vigorsi, copyright Udo Schmidt.


Many of the carabid ground beetles tend to attract a lot of attention from amateur entomologists due to their size and striking appearance, but it must be admitted that they are often not the easiest of animals to work with from a taxonomic perspective. The larger species tend to fall into the category of 'big, black, massive sharp mandibles' and it can require a lot of practice to reliably identify which genus a specimen belongs to, let alone species.

Trichosternus is a genus of ground beetles found in far eastern Australia, from the base of Cape York in Queensland to a bit north of Sydney in New South Wales, in the band of land between the coast and the Great Dividing Range. There is also a single isolated species T. relictus in the southwest corner of Western Australia, and apparently another in New Caledonia (Darlington 1961). However, considering the difficulty that many authors have had in the past in providing an exact definition for Trichosternus relative to other closely related genera, it would be interesting to see if future studies corroborate the inclusion of these outlying species. By way of contrast, a reasonable number of New Zealand species assigned at one time or another to Trichosternus have all long since been moved elsewhere.

Trichosternus species are all flightless and in most the elytra are fused and cannot open (the exception is T. relictus). Most species have a distinctive male genital morphology, with the genital opening deflected to the right and the right paramere (the parameres are two sclerotised 'arms' on either side of the genitalia) modified into a specialised falcate shape, the exact functional significance of which seems to remain unknown. Again, the outlier in this regard is T. relictus in which said paramere retains a primitive styloid shape. Similar falcate parameres are also known from members of related genera such as Megadromus and Nurus; the latter is particularly similar to Trichosternus with the only real difference between the two being that Nurus is more robust with longer mandibles. Trichosternus relictus also has a distinctive female genital morphology, in which the internal passage between the median oviduct (where emerging eggs are fertilised by sperm stored in the spermatheca) and the vagina is remarkably extended and concertina-like. Again, the function of this structure is unknown though Moore (1965) suggested that it might be related to viviparity.

Northern Trichosternus species found in tropical Queensland are all inhabitants of rainforest (hence the restriction of the genus to east of the Great Dividing Range: on the western side of the range, rainforests are absent and the arid zone begins). Southern species are found in upland temperate rainforests or in savannah woodland (Darlington 1961). Some species have very restricted ranges: T. montorum, for instance, is known from two mountains on the Spec Plateau, Mts Bartle Frere and Bellenden Ker.

REFERENCES

Darlington, P. J., Jr. 1961. Australian carabid beetles VII. Trichosternus, especially the tropical species. Psyche 68 (4): 113–130.

Moore, B. P. 1965. Studies on Australian Carabidae (Coleoptera). 4.—The Pterostichinae. Transactions of the Royal Entomological Society of London 117 (1): 1–32.

The Lonely Life of the Cave Collembolan

For a few weeks last year, I had the job of sorting and identifying a collection of Collembola, springtails. Prior to doing this work, I had only the vaguest of understandings of springtail diversity: I knew that there were the round blobby ones, the long thin ones, and the ones that look a bit like sausages, but that was about as far as it went. Needless to say, there's a bit more to it than that.

Pseudosinella immaculata, copyright Andy Murray.


Pseudosinella is the largest genus of Collembola currently recognised, with over 280 described species. The greater number of those species are in Europe and North America, but various Pseudosinella have also been described from other regions of the world (there don't appear to be any from South America, but then I don't know how thoroughly anyone's looked). Pseudosinella species are mostly associated with subterranean habitats, from soil and litter to deep caves, with the highest diversity in the latter. According to a key at collembola.org, Pseudosinella are distinguished from related genera by having reduced eyes (with six or fewer ommatidia, as opposed to the eight ommatidia of other genera), and a bidentate mucro lacking a projecting lamella (the mucro is the claw-like structure at the end of the furcula, the posteroventral prong that forms a springtail's 'spring'). The key also distinguishes Pseudosinella from the similar genus Rambutsinella by it's not having the fourth antennal segment swollen as in the latter, but Bernard et al. (2015) described the species Pseudosinella hahoteana as also having the fourth antennal segment swollen so I'm not sure how reliable that feature is. Pseudosinella is very similar to another genus Lepidocyrtus, the main difference between the two being Pseudosinella's reduced eyes, and more than one author has raised the possibility that Pseudosinella may be a polyphyletic assemblage derived from Lepidocyrtus adapted for life underground.

As well as the reduced eyes, Pseudosinella tend to show a number of other features commonly associated with a subterranean lifestyle, such as a pale coloration and relatively elongate appendages. The claws of the feet also tend to become modified, with the larger of the two becoming longer and progressively narrower (Christiansen 1988). This latter feature is probably an adaptation to movement on the wet surfaces that predominate in caves. At a moderate length, the claws dig into the substrate surface more than those of surface-dwelling forms, allowing greater grip. At longer lengths, the claws are suited to allow the springtail to walk over the surface of the water itself (most springtails float on water surfaces due to their small size and low density, but not all can move with purpose in this position).

Pseudosinella hahoteana, from Bernard et al. (2015). Scale bar = 200 µm.


The aforementioned Pseudosinella hahoteana is worthy of extra attention, as it is one of a half-dozen springtail species endemic to caves on Rapa Nui, the landmass previously known as Easter Island. Many of you will be aware of the ecological catastrophe that beset Rapa Nui following human settlement, as its entire forest covering was cleared away. As a result of this clearing, the native fauna was also all but wiped out; no vertebrates survive, and of about 400 arthropods known from the island only about twenty are indigenous (Bernard et al. 2015). As such, the handful of minute animals clinging to survival in patches of ferns and moss at the entrance to caves represent a significant proportion of Rapa Nui's surviving native fauna.

REFERENCES

Bernard, E. C., F. N. Soto-Adames & J. J. Wynne. 2015. Collembola of Rapa Nui (Easter Island) with descriptions of five endemic cave-restricted species. Zootaxa 3949 (2): 239–267.

Christiansen, K. 1988. Pseudosinella revisited (Collembola, Entomobryinae). Int. J. Speleol. 17: 1–29.

Define 'Trichostomum'


The moss in the above photo Icopyright Hermann Schachner) generally goes by the name of Trichostomum crispulum. Trichostomum is a cosmopolitan genus in the Pottiaceae, the largest recognised family of mosses with about 1500 species overall. But with great diversity comes great difficulty of identification. Pottiaceae tend to be small mosses that are common in harsh habitats. Features of pottiaceous mosses are often hard to distinguish and may be quite variable, making it difficult to confidently define taxa. As a result, Pottiaceae is a prime example of what I like to call 'taxonomic blancmange': something that tends to just get prodded nervously then backed away from when it wobbles ominously.

Characteristic features of Trichostomum as it is commonly recognised tend to include symmetric leaves with more or less plane margins, and with the basal cells of the leaf differentiated straight across the blade or in a U-shape. The peristome of the capsule also tends to be short and straight, and the sexual system is usually dioicous (with separate male and female plants) (Flora of North America). However, none of these features are entirely reliable, and some species have been the subject of extensive disagreement about whether they should be placed in Trichostomum, or in a related genus such as Weissia or Tortella.

To date, only a selection of Pottiaceae species have been subject to molecular analysis, but these analyses have confirmed the unsatisfactory nature of the current system. A molecular phylogenetic analysis of the pottiaceous subfamily Trichostomoideae by Werner et al. (2005) did not identify Trichostomum species as a monophyletic clade; instead, various representatives of the 'genus' were scattered throughout the subfamily. The type species of Trichostomum, T. brachydontium, was associated with a few close relatives such as T. crispulum in a broader clade containing numerous species of the genus Weissia. As a result, it has been suggested that the two genera should perhaps be synonymised, in which case the name Trichostomum would be absorbed by the older Weissia. But first, someone would need to work out just how such a genus could be recognised...

REFERENCE

Werner, O., R. M. Ros & M. Grundmann. 2005. Molecular phylogeny of Trichostomoideae (Pottiaceae, Bryophyta) based on nrITS sequence data. Taxon 54 (2): 361–368.

Cryptophytes: Four Genomes for the Price of One

Sometimes, the little things really do make a difference. Cryptophytes (or cryptomonads) are one of the many groups of minute flagellate protists to be found around the world whose role in our lives tends to get dismissed because of their microscopic size. Nevertheless, cryptophytes make up a large part of the photosynthetic phytoplankton in both freshwater and marine habitats and so ultimately are a starting point for many of the food chains that we depend on. They also had an important role to play in our developing understanding of how modern eukaryote cells have evolved.
Structure of a typical cryptophyte, from here.


As well as occurring in the phytoplankton, cryptophytes have also been found in damp soil and snow. They have a distinctive, slightly lop-sided cell morphology with two haired flagella of unequal length inserted in an invaginated gullet towards the right side of the front of the cell. This invagination is also lined on the ventral side by organelles called ejectosomes (sometimes spelled 'ejectisome'). When the organism is threatened, these ejectosomes shoot out a proteinaceous ribbon that propels the cell rapidly away from the source of irritation. Some of the references to ejectosome function that I've found seem to imply that the expelled ribbon is itself toxic, but I'm not sure if I've understood correctly. Smaller ejectosomes may also play a role in capturing bacteria and the like for the cryptophyte to feed on. Cryptophytes have a distinctive way of moving through the water column, resulting from the uneven lengths of their two propellent flagella, that has been reffered to as 'recoiling'. Essentially, they move in a series of circular tumbles while the cell itself corkscrews around its axis. This movement is distinctive enough that cryptophytes have been dubbed with the Dutch vernacular name of 'rekylalger', 'recoiling algae' (Novarino 2003).

Diagram of typical cryptophyte movement, from Novarino (2003).


The majority of cryptophytes are heterotrophic: one or more large chloroplasts provide much of the cell's energy, but they are also capable of ingesting particulate matter through the gullet. As alluded above, the cryptophyte chloroplast has been significant in the study of how chloroplasts evolved. The 1960s and 1970s saw an increasing acceptance of the concept that some organelles, most notably mitochondria and chloroplasts, had originally appeared through a process of endosymbiosis: bacteria had become intimately associated with eukaryote cells, becoming embedded in the host cell and eventually ceding enough of their vital functions to the host to be unable to function as independent organisms. The chloroplasts of the ancestors of land plants arose in this manner from cyanobacteria, as indicated by the presence of a remnant but reduced bacterial genome within the chloroplast itself, and the presence of a double membrane around each chloroplast (corresponding the cyanobacterium's original cell membrane, plus the vacuoule membrane in which it had been enclosed by the host eukaryote). In the early 1970s, however, it was found that cryptophyte chloroplasts have not two but four surrounding membranes. What is more, wedged between two of those membranes was a tiny remnant cell nucleus, dubbed the nucleomorph. The nucleomorph was a crucial piece of evidence in demonstrating that cryptophyte chloroplasts had arisen by a process of secondary endosymbiosis. A eukaryote cell containing a chloroplast that had arisen in the manner described above was itself engulfed and converted to a chloroplast by another eukaryote. The four membranes around the cryptophyte membrane were therefore, from the inside out, the original cyanobacterium cell membrane, the vacuole membrane containing the cyanobacterium, the cell membrane of the primary host cell (with the nucleomorph between this and the last), and the vacuole membrane in which that had been contained in turn. Other groups of eukaryotes also have chloroplasts that arose in this way, such as brown algae and dinoflagellates, but in these the nucleus of the captured eukaryote cell has entirely disappeared.

Another cryptophyte structural diagram of the species Guillardia theta, showing the arrangement of the chloroplast, from here. This also shows the sites of the four genomes contained in the typical cryptophyte cell.


Exactly when the cryptophyte chloroplast arose remains a contentious subject. Various lines of evidence point to the captured chloroplast donor being a red alga, as is also the case with the aforementioned brown algae and dinoflagellates. As such, some have argued for the chloroplasts of all such algae being descended from a single capture event. However, there are also a number of protists related to such taxa that lack chloroplasts. In the case of cryptophytes, there is strong evidence that the sister clade to the the photosynthetic cryptophytes is the chloroplast-less genus Goniomonas. The subsequent sister to these two clades together is less certain but a number of recent studies have pulled forward another chloroplast-less group, the katablepharids. If the cryptophyte chloroplast shares an origin with that of brown algae, then it must have somehow been lost in the ancestors of both Goniomonas and katablepharids. So far, an author's preference for a single or multiple origins of red alga-derived chloroplasts tends to come down to whether they think it is easier for chloroplasts to be lost or gained, a question whose answer is still unclear.

The diversity within cryptophytes is still not that well understood, largely due to difficulties in observing significant characters. Prior to the advent of scanning electron microscopy, some authors had gone so far as to dismiss cryptophytes as essentially unclassifiable. Nevertheless, not everything was as bleak as the pessimists would have it. Cryptophyte taxa may differ from each other in overall size and shape. They may also differ in cell colour, due to the presence of various accessory pigments in addition to chlorophyll. The primary accessory pigments found in cryptophytes are known as phycocyanin and phycoerythrin; species containing the former are a blue-green colour whereas those containing the latter are reddish, golden or a greenish yellow. The use of scanning electron microscopy has led to the discovery of other useful features such as those relating to the periplast, a protein envelope that covers the inside and outside of the cryptophyte cell membrane. Electron microscopy has shown that the outer periplast layer is often ornamented, such as by being divided into scales. And even more recently, of course, researchers have recognised the value that molecular tools may have to offer cryptophyte taxonomy, though said tools have also complicated matters by, for instance, giving hints that previously recognised 'taxa' may represent different life cycle stages of a single organism. Whatever the eventual result, there is no question that we still have a lot to learn about cryptophytes.

REFERENCE

Novarino, G. 2003. A companion to the identification of cryptomonad flagellates (Cryptophyceae = Cryptomonadea). Hydrobiologia 502: 225–270.

Sweepers

It's time to meet the sweepers.

Smallscale bullseyes Pempheris compressa, copyright John Turnbull.


Sweepers, Pempheridae, are a group of moderately sized marine fish (usually about fifteen to twenty centimetres in length) found around tropical reefs in the Indo-Pacific and western Atlantic. I don't know why they're called sweepers, but in some areas they may be among the most abundant fish on the reef. Distinctive features of the group include a short, high dorsal fin and a long anal fin. The lateral line is also distinctively long, extending past the end of the tail right onto the caudal fin. Perhaps the feature that most stands out about sweepers is their large eyes. The eyes are so big because sweepers are nocturnal; during the day they retreat into protected crevices and caves, emerging at night to feed on minute crustaceans and other small animals (Mooi 2001).

Pygmy sweeper Parapriacanthus ransonneti, from here.


Sweepers are divided between two quite distinct genera. Members of the genus Parapriacanthus have a more 'average fish-like' elongate profile with the body less deep than the head is long. The other genus, Pempheris, has a distinctively deep profile, deeper than the head is long. The exact number of species of pempherid appears to still be uncertain. Pempherids lack the striking markings of other tropical fish and species can appear very similar to each other. What is more, they have two layers of scales on the body, with the outer scales being larger than the inner and deciduous (easily shed), and loss of the outer scales has the potential to change an individual's superficial appearance. Early descriptions of pempherid species are often inadequate for their reliable identification, and new species continue to be described at a quite rapid pace. A recent publication by Randall & Victor (2015), for instance, described no less than thirty-four new species of Pempheris from various locations in the Indian Ocean, close to doubling the number of species in the genus at a stroke. The genus Parapriacanthus is much less diverse, with only about five recognised species.

Orange-striped bullseyes Pempheris ornata in hiding during the day, copyright Peter Southwood.


Because of their relatively small size and retiring habits, sweepers are mostly not that significant economically. At least one species, Pempheris xanthoptera, is fished off the coast of Japan and mostly eaten as fish paste; it is supposed to be quite tasty. Some have appeared in aquaria.

When foraging at night, sweepers communicate with each other by producing popping noises through muscular flexing of the swim bladder wall. Noise production increases in the presence of potential threats, perhaps to warn other members of the school. At least some pempherid species also have bioluminescent glands associated with the posterior part of the gut. The bioluminescent compound is not directly produced by the fish itself but obtained by consuming bioluminescent ostracods. I haven't found whether the function of this bioluminescence is specifically known for pempherids, but similar ventral glows in other fish provide camouflage by breaking up the fish's silhouette when seen from below.

REFERENCES

Mooi, R. D. 2001. Pempheridae. Sweepers (bullseyes). FAO Species Identification Guide for Fishery Purposes. The Living Resources of the Western Central Pacific vol. 5. Bony fishes part 3 (Menidae to Pomacentridae) pp. 3201–3204. Food and Agriculture Organization of the United Nations: Rome.

Randall, J. E., & B. C. Victor. 2015. Descriptions of thirty-four new species of the fish genus Pempheris (Perciformes: Pempheridae), with a key to the species of the western Indian Ocean. Journal of the Ocean Science Foundation 18: 77 pp.