Life with Termites

Termitusodes lativentris. Image from Seevers (1957).

The Staphylinidae are one of the largest (over 46,000 species) and most easily recognisable of the commonly accepted beetle 'families'. Among other things, they can be readily distinguished from other beetles by the reduction of the elytra so that they no longer cover the abdomen, similar to what is seen in the earwigs. The most familiar staphylinids are relatively large predatory species (known as rove beetles or devil's coach-horses) but the family includes a wide variety of other forms.

The animal rather poorly illustrated at the top of the post is a member of the subtribe Termitusina in the subfamily Aleocharinae. Termitusina are found in tropical Africa where they live within the colonies of certain species of termite. The image doesn't show the distinguishing features of this group very well, unfortunately, but if you look carefully (and perhaps use a bit of imagination) you may be able to make out the strongly deflexed head and ninth abdominal tergite divided between two elongate halves. Unlike many termite-associated staphylinids, Termitusina of the genera Termitusa and Thoracotusa do not generally exhibit physogastry (a swollen abdomen). Termitusodes, the third genus in the subtribe, differs from the other two genera in this respect, though it still comes nowhere near the level of physogastry found in some termite-associated staphylinids.

I haven't been able to find out whether the Termitusina are in some way social parasites of their host termites or whether they are finding their food in the nest some other way (such as by scavenging or feeding on fungi) but the association is undoubtedly a close one. Termitusina are, as a rule, host specific (Jacobson & Kistner, 1975). Termitusa are found only in nests of the termite genera Cubitermes and Noditermes, Thoracotusa is found with Thoracotermes, and Termitusodes has been found with Cubitermes and Pericapritermes magnificus. Pericapritermes often nest in association with Cubitermes (they may occupy abandoned Cubitermes nests or they may invade the nest while the Cubitermes are still living there) and it seems likely that this association is what allowed Termitusodes to change hosts at some point in its history.

REFERENCES

Jacobson, H. R., & D. H. Kistner. 1975. Numeric analyses of relationships of genera and species of the subtribe Termitusina (Coleoptera: Staphylinidae). Systematic Zoology 24 (2): 191-198.

Seevers, C. H. 1957. A monograph on the termitophilous Staphylinidae (Coleoptera). Fieldiana: Zoology 40: 1-334.

Name the Bug # 39

Attribution to follow. And yes, I realise that this image is beyond awful, but would you believe that this was the best that I could find?

Also, you may notice that there's been a bit of a design change here. All credit for that goes to Edward, the benevolent overlord of Field of Science.

Update: Identity now available here. Image from Seevers (1957).

Life in Sand

Paramesochra mielkei, from Huys (1987).

Paramesochra is a genus of minute marine copepods found around the world. Over twenty species are currently assigned to the genus, but it is likely that many more await description. The extremely small size of paramesochrids (most are less than half a millimetre in length) reflects the interstitial habitat of most species described to date, i. e. they live among the grains of sand beneath the surface of their substrate. Also related to their choice of habitat is their vermiform (worm-like) shape and reduced setation compared to other copepods. These features also mean that they would be poor swimmers so they probably do not often emerge above the substrate surface. Most of the species described so far are from shallower waters, but this possibly reflects a lack of study of deep-sea species rather than reflecting true diversity. For instance, a survey of deep-sea Paramesochridae in the southern Atlantic and Antarctic Oceans by Gheerardyn & Veit-Köhler (2009) identified four species of Paramesochra, none of which corresponded to previously described species. These species probably do not have the same lifestyles as the shallow-water interstitial species due to the deep-sea substrate being fine mud rather than sand. Vasconcelos et al. (2009) suggested that another deep-sea paramesochrid, Kliopsyllus minor, might burrow in fluid mud or live in the 'organic fluff layer' (wonderful words) on top of the sediment. Deep-sea Paramesochra would probably be similar.

For the most part, genera of copepods have generally been distinguished mechanistically—different genera have different combinations of key features (usually related to the number of setae or segments on appendages)—without an explicit consideration of how those characters relate to phylogeny. However, Huys (1987) did propose a phylogenetic arrangement for the genera of Paramesochridae in which he suggested that Paramesochra formed a clade with the genera Kliopsyllus and Kunzia on the basis of their possessing single-segmented exopodites on the antennae and mandibles. However, while his tree shows Paramesochra as a monophyletic sister group to a clade of the other two genera, he did not identify any synapomorphies for Paramesochra. Instead, the features distinguishing it from the other two genera (two-segmented endopodites on the second to fourth legs, four setae on the distal exopodite segment of the first leg and two setae on the distal exopodite segment of the fourth leg) are resolved as plesiomorphies relative to the other clade. So if any of you feel inspired to spend your time dissecting and examining the legs of animals about 0.3 of a millimetre in total length, I know a potential research project going begging...

REFERENCES

Gheerardyn, H., & G. Veit-Köhler. 2009. Diversity and large-scale biogeography of Paramesochridae (Copepoda, Harpacticoida) in South Atlantic Abyssal Plains and the deep Southern Ocean. Deep-Sea Research I 56: 1804-1815.

Huys, R. 1987. Paramesochra T. Scott, 1892 (Copepoda, Harpacticoida): a revised key, including a new species from the SW Dutch coast and some remarks on the phylogeny of the Paramesochridae. Hydrobiologia 144: 193-210.

Vasconcelos, D. M., G. Veit-Köhler, J. Drewes & P. J. Parreira dos Santos. 2009. First record of the genus Kliopsyllus Kunz, 1962 (Copepoda Harpacticoida, Paramesochridae) from Northeastern Brazil with description of the deep-sea species Kliopsyllus minor sp. nov. Zootaxa 2096: 327-337.

Name the Bug # 38

These particular animals seem to generally be illustrated in bits:





Attribution to follow.

Update: Identity now available here. Figure from here.

A Review: Tetrapod Zoology: Book One

Naish, D. 2010. Tetrapod Zoology: Book One. CFZ Press: United Kingdom.

This review is probably a little redundant. I suspect that most of my regular readers are probably already familiar with Tetrapod Zoology, Darren Naish's leading blog on all things vertebrates-that-ain't-fish-y. Nevertheless.

The original version of Tet Zoo debuted in January 2006, almost five years ago. Tetrapod Zoology: Book One is a collection of most of the posts which appeared from January to July of that year. For the most part, the text remains the same as it first appeared; the main change is that some of the topics that appeared as multiple posts have beeen fused into single chapters. The included chapters cover topics from cave-dwelling salamanders to corpse-hunting turtles, from contentious monkeys to elusive warblers. As always, Darren has the rare knack of combining breezy readibility with an extraordinary wealth of detail. And as well as chapters on dramatic topics such as giant pterosaurs and British big cat sightings, the book contains examples of Darren's even more admirable ability to highlight the extraordinary sides of seemingly unremarkable animals such as rabbits, gulls and owls.

There are few bloggers who could pull off a simple transition from blog post to book like Darren has, and even in Darren's case I'm not sure the process has been completely successful. The original appearance of the book's chapters as independent units means that there is a noticeable lack of connection between most of them, nor is there any obvious pattern to the topics covered. Also, some of the chapters might have been expected to have received more editing had they originally gone through a more leisurely . A chapter on stem-whale diversity refers to 'whales with trunks' both in the title and in the introductory paragraphs, but fails to enlarge on this further. Also, the time that has elapsed since the original composition of the chapters and their publication in the book means that some of the chapters can seem a little dated; both in obvious ways (references to 'recent' events that are no longer recent) and not-so-obvious ways (would Darren have revised his comments on Michael Heads' biogeography of birds-of-paradise had he known that Heads would later use the same principles to argue for a Jurassic divergence of modern primates?)

Such issues are not unique to blogs, of course—had this been a collection of magazine essays or newspaper columns, there would be cause for the same complaints. Still, I feel that the layout of this book should have embraced its history more, rather than simply presenting the sections as if they were written for the book. It would have been nice to have been given the original release date for each of the chapters (Darren does make it clear in the introduction that they were written in 2006, but it would have been good to have individual dates, ideally at the head or foot of each chapter). If nothing else, doing so would allow the inclusion of Darren's legendarily detailed April 1 posts*. Also, while Darren does include an update section in the book's introduction mentioning some of the significant events that have happened since relevant to the original chapters, it may have been better to present each chapter's updated separately as an addendum to the chapter itself. And I'm surprised that Darren failed to mention Roosmalen et al. (2007) in which the new peccary species discussed in the final chapter was named Pecari maximus (the validity of the species apparently remains contentious).

*I'm also personally disappointed by the absence of one of my favourite Tet Zoo posts from the period included—indeed, one of my favourites of all time—the story of Walter Rothschild and his all-consuming cassowary obsession.

None of these complaints, of course, are particularly serious. Most of them disappear if the book is read as its contents were originally intended: not as a unit, but as a series of fascinating essays to be indulged in, one chapter or two at a time, when looking for a half-hour or so's entertainment. And there would be few people indeed who would fail to come away from it without an increased sense of wonder about the animals it describes. Of course, you may be wondering why you should be paying for something that is available for free online. To which I can simply point out that, as well as the moral satisfaction of doing your part to help keep Darren and his family in stockings and fans, the success of this book can only encourage him to produce more. Hopefully, Tetrapod Zoology: Book Two will not be long in coming.

REFERENCE

Roosmalen, M. G. M. van, L. Frenz, P. van Hooft, H. H. de Iongh & H. Leirs. 2007. A new species of living peccary (Mammalia: Tayassuidae) from the Brazilian Amazon. Bonner Zoologische Beiträge 55 (2): 105-112.

Learning to Like Lichen

The lichen Parmelia saxatilis. The red cups at the top of the photo are the lichen's fruiting bodies (apothecia) that produce fungal spores. Photo from here.

We all know what lichens are. They're the standard example of a mutualistic association that we were all presented with in high school, an association of fungus and unicellular alga allowing both to survive long-term in situations that would normally be fatal for them both. More than 15,000 species of lichen have been described—or, rather, species of lichenised fungi, as names applied to lichens technically apply to the fungal member of the association (only a relatively small number of algae form lichen associations). Though these species can all be attributed to the Ascomycetes among the main fungal subdivisions*, they do not form a single clade within the asomycetes. Instead, it appears that the lichen lifestyle has been gained and/or lost on numerous occasions.

*Lichen-like associations are sometimes formed by other fungi such as Basidiomycetes but they lack the integrity of the ascomycetous examples. Lab workers have even been able to induce lichen-like associations between unicellular algae and colonial or hyphal bacteria such as myxobacteria and streptomycetes (Ahmadjian 1965).

Parmelia is a genus of foliose lichens which is found worldwide but has its highest diversity in Asia (Molina et al. 2004). Well over 1000 species have been assigned to the genus over the years but many (though not all) recent authors have tended towards a much more restricted circumscription of about forty species. True Parmelia, in this sense, is distinguished from other genera in the lichen family Parmeliaceae by its linear pseudocyphellae (pore-like structures in the upper-surface of the lichen's cortex) and its particularly small spores and conidia (conidia are reproductive structures like spores but produced asexually rather than sexually) (Elix 1993). ITS rDNA phylogeny is mostly consistent with many of the proposed segregate genera, including the restricted Parmelia, though it provides little information on their higher relationships (Crespo & Cubero 1998).


Another view of Parmelia saxatilis. As well as the spore-producing apothecium, this photo also shows numerous isidia, the small finger-like protrusions covering the thallus. Containing both fungal and algal cells, the isidia can break off to form new lichens. Photo by Stephen Sharnoff.

Parmelia achieves its highest diversity in temperate or boreal regions. The type species, P. saxatilis, is one of the world's most widespread lichen species, found in both the Arctic and the Antarctic, as well as cooler localities in between (Molina et al. 2004). Lichens can reproduce in one of two ways: small pieces of the thallus containing both algal cells and fungal hyphae may break off to grow directly into a new thallus elsewhere, or the lichen can release spores and/or conidia in the manner of other fungi. A germinating lichen spore will grow extremely slowly: even in laboratory cultures on agar, some lichen fungi will only reach a diameter of 1 mm within the course of a year when grown without algal symbionts(Ahmadjian 1965). Formation of the lichen association is dependent on the fungus randomly coming into contact with an alga, and growing lichen fungi will form exploratory hyphae around anything (even grains of sand) that they touch that might turn out to be an alga (Ahmadjian 1960). The low variety of algal species occuring in lichens appears to be dependent not on any direct attraction of the alga for the fungus, but on the alga's ability to resist digestion by the fungus' hyphae. Lichens are famed for their slow growth even after an association is established, and may increase in diameter by only a millimetre a year*, but the limiting factor is probably not so much their inherent growth abilities as that their favoured environments such as exposed on rocks may only allow growth for a minute part of the year.

*If you're thinking that that doesn't sound any greater than the rate for symbiont-less fungi that I cited above, remember that the latter rate applies to growth in the laboratory under theoretically optimal conditions; growth in the natural environment would be much, much slower.

REFERENCES

Ahmadjian, V. 1960. The lichen association. Bryologist 63 (4): 250-254.

Ahmadjian, V. 1965. Lichens. Annual Review of Microbiology 19: 1-20.

Crespo, A., & O. F. Cubero. 1998. A molecular approach to the circumscription and evaluation of some genera segregated from Parmelia s. lat. Lichenologist 30 (4-5): 369-380.

Elix, J. A. 1993. Progress in the generic delimitation of Parmelia sensu lato Lichens (Ascomycotina: Parmeliaceae) and a synoptic key to the Parmeliaceae. Bryologist 96 (3): 359-383.

Molina, M. del C., A. Crespo, O. Blanco, H. T. Lumbsch & D. L. Hawksworth. 2004. Phylogenetic relationships and species concepts in Parmelia s. str. (Parmeliaceae) inferred from nuclear ITS rDNA and β-tubulin sequences. Lichenologist 36 (1): 37-54.