The Live-Bearing Brotulas

Black brotula Stygnobrotula latebricola, photographed by Thomas W. Doeppner.

The subject of today's post is the Bythitidae, a family of mostly marine fishes referred to as the live-bearing brotulas. Bythitids belong to the Ophidiiformes, a group of more or less elongate fishes with long soft dorsal and anal fins. They differ from most other ophidiiforms in that the males have an external intromittent organ and they are mostly live-bearers rather than egg-layers (though at least one species, Didymothallus criniceps, is potentially an egg-layer: Schwarzhans & Møller 2007). Bythitids do share these features with the deep-water Aphyonidae, which are however particularly elongate, lack scales and a swim bladder, and have loose translucent skin in contrast to the firm skin of bythitids (Nielsen et al. 1999).

Bahamian cave fish Lucifuga spelaeotes, photographed by Joe Dougherty.

Bythitids are often thought of as deep-water fishes, but there is also a reasonable diversity of them in shallower habitats such as coral reefs. The shallower-living species are mostly very cryptic in their habits and may be only rarely encountered; deeper-water species may occupy more open habitats or be found in association with hydrothermal vents. Some species of the genera Lucifuga and Ogilbia are found in freshwater caves in the Caribbean (Lucifuga species), the Yucatan (Ogilbia pearsei) and the Galapagos (O. galapagosensis); other species are found in marine caves such as the 'blue holes' of the Bahamas. New species of bythitid continue to be described at a reasonable rate of knots (over 100 species have been described in the last ten years alone). They vary in size from small (Microbrotula species are about four centimetres in length) to very large (Cataetyx laticeps reaches over 75 cmm; the Fishes of Australia website states that bythitids grow up to 2 m, but I haven't been able to find which species this refers to).

Yellow cuskeel Dinematichthys iluocoeteoides, from here.

Because of their cryptic habits, the lifestyles of most bythitids remain poorly known. They are predators of invertebrates and other fish. The few identified larvae have been collected in the epipelagic zone (Nielsen et al. 1999) but bythitids are believed to have relatively low fecundity rates (presumably as only small numbers of embryos have been found in gravid females). Reef-dwelling species, as far as is known, have only small ranges, and many may be endangered by habitat degradation.

REFERENCES

Nielsen, J. G., D. M. Cohen, D. F. Markle & C. R. Robins. 1999. FAO species catalogue. Volume 18. Ophidiiform fishes of the world. An annotated and illustrated catalogue of pearl-fishes, cusk-eels, brotulas and other ophidiiform fishes known to date. FAO Fisheries Synopsis 125 (18): I–XI + 1–178.

Schwarzhans, W., & P. R. Møller. 2007. Review of the Dinematichthyini (Teleostei: Bythitidae) of the Indo-west Pacific. Part III. Beaglichthys, Brosmolus, Monothrix and eight new genera with description of 20 new species. The Beagle, Records of the Museums and Art Galleries of the Northern Territory 23: 29-110.

Limpets of the North-east Atlantic

The common limpet Patella vulgata, photographed by Rokus Groeneveld.

When Linnaeus published the tenth edition of his Systema Naturae in 1758, he defined the genus Patella as having a subconical shell with a single valve and without a respiratory opening. Starting from this fairly minimal set of criteria, it is not surprising that a very broad range of limpets from all over the world ended up passing through Patella at various times. However, as time goes by the definition of Patella became further refined, and currently both morphological (Ridgway et al. 1998) and molecular (Nakano & Ozawa 2004) studies have tied the name Patella to a clade of limpets found only in coastal waters of the north-east Atlantic Ocean and the Mediterranean.

The giant limpet Patella ferruginea, up to eight centimetres in diameter, photographed by E. Volto.

This restricted sense of Patella includes nine or ten recognised species, though discussions are ongoing about whether given populations should be regarded as conspecific or not, and a large number of subspecies have been described. Limpets are fairly conservative animals morphologically, offering a fairly narrow range of characters for taxonomic study. Matters are further confused by a certain degree of environmentally-related plasticity: individuals living higher in the tidal zone tend to be larger and higher-spired than individuals living subtidally (Weber & Hawkins 2002). Patella limpets are generally believed to be protandrous, starting their lives as males and eventually metamorphosing into females; however, a study monitoring sex changes in P. vulgata identified one individual that changed from female to male (Le Quesne & Hawkins 2006). Patella limpets have been used for food by humans in many parts of their range, and collection pressure is regarded as a significant threat to the endangered western Mediterranean species P. ferruginea.

Blue-rayed limpets Patella pellucida, from here.

Within the family Patellidae, the distribution of Patella is notably unusual: this genus is largely geographically isolated from other patellids in southern Africa and the Indo-Pacific. Only a single other patellid species, the western African Cymbula safiana, has a range overlapping with Patella species (Ridgway et al. 1998). The fossil record contains little evidence how this separation came about: patellids are rarely preserved, living as they do in high-energy environments, and their morphological simplicity makes them difficult to identify though genera can be distinguished by their shell microstructure. Patella proper has not been reliably identified earlier than the Pliocene (Ridgway et al. 1998). It has been suggested that the ancestors of Patella either migrated up the western coast of Africa, or became separated from other patellids by the closure of the Tethys Sea that once connected what is now the Mediterranean with the Indian Ocean. However, molecular analyses have placed Patella as the sister taxon to all other patellids; if correct, this could push its separation back past the Upper Cretaceous as a Japanese fossil from that time has been assigned to the patellid genus Scutellastra. This would be too early for the African dispersal or Tethyan explanations, and new proposals are required.

REFERENCES

Le Quesne, W. J. F., & S. J. Hawkins. 2006. Direct observations of protandrous sex change in the patellid limpet Patella vulgata. Journal of the Marine Biological Association of the United Kingdom 86: 161-162.

Nakano, T., & T. Ozawa. 2004. Phylogeny and historical biogeography of limpets of the order Patellogastropoda based on mitochondrial DNA sequences. Journal of Molluscan Studies 70: 31-41.

Ridgway, S. A., D. G. Reid, J. D. Taylor, G. M. Branch & A. N. Hodgson. 1998. A cladistic phylogeny of the family Patellidae (Mollusca: Gastropoda). Philosophical Transactions of the Royal Society of London Series B 353: 1645-1671.

Weber, L. I., & S. J. Hawkins. 2002. Evolution of the limpet Patella candei d’Orbigny (Mollusca, Patellidae) in Atlantic archipelagos: human intervention and natural processes. Biological Journal of the Linnean Society 77: 341-353.

Bryaxis on the Prowl

Pselaphine, probably Bryaxis bulbifer, photographed by Krister Hall.

Bryaxis is a large genus, with over 400 described species and subspecies (Hlaváč 2008), of small beetles belonging to the group known as the Pselaphinae, a subgroup of the Staphylinidae. In older references, you'll see the pselaphines referred to as a separate family Pselaphidae from the staphylinids, but most authors now include it in the latter as it has become clear that the pselaphines are not only related to the staphylinids but nested well within them. It is not so surprising that this was not immediately recognised: your average staphylinid looks something like this:

Paederus riparius, from here.

Bryaxis species are mostly found living in leaf litter, where they are predators of other micro-arthropods such as springtails. If you look at the top photo, you will be see two appendages with paddle-shaped endings attached to the head just behind the antennae. These are the maxillary palps, often enlarged in pselaphines (sometimes ridiculously so). Glands on the inside of the palp 'paddle' produce a sticky secretion, and the palps are used to grab the prey when hunting. The process of prey capture in Bryaxis puncticollis was illustrated by Schomann et al. (2008):

Prey detected!

Palps at the ready...

Pounce!

The final parts of the process. The springtail is held tail-upwards so that it can't escape or injure the beetle using the forked furca, the 'spring' underneath its abdomen.

As befits a large genus, Bryaxis has a truly headache-inducing taxonomic history, summarised by Besuchet (1966). The genus was first named by Kugelann in 1794. Kugelann's work can't have been that widely publicised, however, because in 1817 Leach gave the name Bryaxis to a different genus of pselaphine. Most subsequent authors used Bryaxis in the sense of Leach, and included Kugelann's original Bryaxis in the genus Bythinus, until this was corrected by Raffray in 1904. Raffray treated Bythinus as a junior synonym of Kugelann's Bryaxis, and placed Leach's 'Bryaxis' under the name Rybaxis. Even so, some European authors persisted in using Leach's Bryaxis.

It wasn't until the 1950s and 1960s that the usage of Bryaxis became stabilised, but there was one further wrinkle to the story. When Raffray identified Bythinus as a synonym of the true Bryaxis, he separated out a few previous Bythinus species as a new genus Bolbobythus. However, one of those was the type species of Bythinus. So, as finally laid out by Besuchet (1966): what had been called 'Bolbobythus' was really Bythinus, 'Bythinus' was really Bryaxis, and 'Bryaxis' was really Rybaxis! What could be simpler?

REFERENCES

Besuchet, C. 1966. Bryaxis Kugelann, 1794 and Bythinus Leach 1817 (Insecta, Coleoptera): proposed addition to the Official List in their original sense. Bulletin of Zoological Nomenclature 23 (2-3): 114-116.

Hlaváč, P. 2008. A new cavernicolous species of the genus Bryaxis (Coleoptera: Staphylinidae: Pselaphinae) from the island of Mljet. Natura Croatica 17 (1): 1-8.

Schomann, A., K. Afflerbach & O. Betz. 2008. Predatory behaviour of some Central European pselaphine beetles (Coleoptera: Staphylinidae: Pselaphinae) with descriptions of relevant morphological features of their heads. European Journal of Entomology 105: 889-907.

The Psocoptera of Barrow Island

Courtenay Smithers, courtesy of the Sydney Morning Herald.

Gunawardene, N. R., C. K. Taylor & J. D. Majer. 2012. Revisiting the Psocoptera (Insecta) of Barrow Island, Western Australia. Australian Entomologist 39 (4): 253-260.

Our lab has just recently added to its publication list with the above title, which is part of a special issue of the Australian Entomologist printed in memory of the late Courtenay Smithers, who passed away last year. For many years, Courtenay was one of Australia's leading entomologists, particularly for those unfairly overlooked animals the bark-lice (non-parasitic Psocodea). An obituary for him can be found here.

We wanted to include this paper as a tribute to Courtenay, as it basically presents some identification work that he had done for us in the last few years. As some of you already know, we've been working for the last few years on surveying the terrestrial invertebrates of Barrow Island, off the north-west coast of Australia. Courtenay had first surveyed the bark-lice of Barrow back in 1982, when he collected only five species of Psocodea all up, including the cosmopolitan synanthrope Liposcelis entomophila (Smithers 1984). Because Barrow Island is a very arid habitat, with little to no standing fresh water, Courtenay felt that "The small size of the fauna is probably a reality not an illusion".

A cute litte critter from our collection that still only goes by the name of 'Pteroxanium sp. A'.

As it turns out, he was wrong. At least 26 species of Psocodea have been found on Barrow so far (the paper says 25, but we've had at least one more turn up since it was accepted for publication). Most of these have currently only been identified as morphospecies: identification of bark-lice is often a difficult task, and many Australian species probably remain undescribed (as an example, Courtenay's 1996 tally of the total described Australian Psocodea for the Zoological Catalogue of Australia includes less species of Liposcelididae than have been collected on Barrow Island alone). Three of the recorded species are synanthropes collected in buildings on the island; as far as we know, these species are not found in unmodified habitat. One of these, Dorypteryx domestica, was particularly interesting to me as it had not been recorded previously from Australia (and was my first real success at identifying a psocodean right down to species level, hurrah!), though Tim New (Australia's remaining bark-louse expert) informed us that its presence has always been expected. I have to say, while bark-lice in general are among the cutest of all insects, but the little jumping Dorypteryx really amps the cuteness right up there.

And here it is! (Photo from Gunawardene er al. 2012.) Dorypteryx domestica is probably found worldwide, but records are scattered because of its unassuming nature.

Unfortunately, Courtenay's passing highlights that a large proportion of taxonomic expertise currently resides in the minds of retired individuals (of the experts who have made identifications of material from the Barrow Island project, nearly a third were either retired or amateur taxonomists working in their spare time). There is no shortage of material out there, but we still need the people to tell us what it is.

Suspiciously posed-looking photo, used in Gunawardene et al. (2012), of yours truly supposedly demonstrating an insect collection method.

REFERENCES

Smithers, C. N. 1984. The Psocoptera of Barrow and Boodie Islands, Western Australia. Entomologica Scandinavica 15: 215-226.

Smithers, C. N. 1996. Psocoptera. In: Wells, A. (ed.) Zoological Catalogue of Australia. Psocoptera, Phthiraptera, Thysanoptera pp. 1–79. CSIRO Publishing: Melbourne.

Mayflies in their Spring

Armoured mayfly Baetisca obesa, photographed by Jason Neuswanger.

Mayflies have occasionally put in an appearance here at CoO, most notably in an earlier post where I explained how the one thing that everyone 'knows' about mayflies is simply not true. In this post, I thought that I'd look briefly at the fossil context of mayflies.

The basalmost relationships among insects have been subject to some discussion over the years, but the current majority view is probably that mayflies were the first of the living winged insect lineages to diverge from the rest. Evidence for this is their retention of some plesiomorphic features such as the presence of three caudal filaments at the end of the abdomen, and a sliding rather than fixed inner mandibular articulation in the nymphs (adult mayflies don't have functional mouthparts). Mayfly nymphs, offhand, are known as naiads. Naiads were originally supposed to be nymphs that inhabited freshwater springs, so at some point the term 'naiad' was transferred from this:

Hylas and the Nymphs, by John William Waterhouse, in which our hero is fatally tempted by a septet of skinnydipping broads.
to this:

Drunella cornuta, photographed by Jonas Insinga.
Which I'm sure came as something of a disappointment to Hylas (though, of course, had Hylas been more disappointed, he may have also been less dead).

As discussed in an earlier post on stoneflies, there is some uncertainty whether aquatic nymphs are ancestral or derived for winged insects. However, mayflies were spending the first part of their lives in water by at least the Permian (Kluge & Sinitshenkova 2002; Grimaldi & Engel 2005). Representatives of the mayfly crown group (i.e. the group stemming from the most recent common ancestor of all living mayflies) are not known until the Jurassic; earlier species all belong to the stem group. The Carboniferous Syntonopterodea may also be stem-mayflies, but in superficial appearance the large, broad-winged syntonopterodeans may have looked more like the contemporary palaeodictyopteroids.

Reconstruction of Protereisma permianum, one of the best known of the Permian stem-mayflies, via here.

The Permian and Jurassic Ephemeroptera themselves had some notable differences from crown-group mayflies. Modern mayflies have heteronomous wings, with the fore- and hind wings differing in size (in some mayflies, the hind wings have almost disappeared entirely). Permian mayflies, in contrast, had homonomous wings, with the two pairs more or less identical; the hind wings became shortened in Triassic stem-mayflies (Grimaldi & Engel 2005). At least some stem-mayflies also retained well-developed mouthparts as adults; this suggests that they may well have lived longer as adults than modern mayflies. While Grimaldi & Engel (2005) included Permian and Triassic species in the Ephemeroptera, Staniczek et al. (2011) restricted that name to the crown group and its nearest and dearest, placing most of Grimaldi & Engel's stem-group 'Ephemeroptera' into an extinct clade Permoplectoptera.

REFERENCES

Grimaldi, D., & M. S. Engel. 2005. Evolution of the Insects. Cambridge University Press: New York.

Kluge, N. Yu., & N. D. Sinitshenkova. 2002. Order Ephemerida Latreille, 1810. The true mayflies (=Ephemeroptera Hyatt et Arms, 1891 (s. l.); =Euephemeroptera Kluge, 2000. In History of Insects (A. P. Rasnitsyn & D. L. J. Quicke, eds) pp. 89-97. Kluwer Academic Publishers: Dordrecht.

Staniczek, A. H., G. Bechly & R. J. Godunko. 2011. Coxoplectoptera, a new fossil order of Palaeoptera (Arthropoda: Insecta), with comments on the phylogeny of the stem group of mayflies (Ephemeroptera). Insect Systematics and Evolution 42: 101-138.

The Prostigmata: Endless Forms

Water mite, possibly Piona coccinea, photographed by Roger Key.

Some groups are just so diverse that it is difficult just to know where to start in introducing them. My topic for today, the mites of the Prostigmata, are definitely one of those groups. Even though few would doubt the coherence of the Prostigmata, their morphological diversity is such that it is difficult to identify features that characterise them all. The majority are small and/or poorly sclerotised mites, but some species are extremely large (by mite standards, at least) and others are heavily armoured. The name 'Prostigmata' refers to the presence in many species of tracheae with the spiracle openings between the cheliceral bases, but many lack tracheae. In one group, the Heterostigmatina, the males and juveniles usually lack tracheae but adult females have tracheae with the spiracles placed at the front of the sides of the body, outside the chelicerae. Prostigmatans include predators, plant-feeders and parasites; their chelicerae, accordingly, may be pincer-like like those of other mite groups, or they may be variously modified. Many groups have the chelicerae fused into a puncturing stylophore; others have the mobile finger adapted into a protruding blade or stylet. The plant-feeding spider mites of the Tetranychoidea have the mobile fingers modified into long thin whips that can be retracted right back into the body, or extended to form the two halves of a sap-sucking tube. Even such features as the number of legs can't always be relied upon: while most Prostigmata have eight legs as is usual for arachnids (though, as with other mites, the fourth pair of legs only develops in the post-larval instars), the hind pairs are reduced or lost in a number of parasitic groups. The gall-forming plant mites of the Eriophyoidea have only four legs at the very front of the body, with an anal sucker at the end of the body to hold them in place.

The labidostomatid Sellnickia, from Macromite.

The phylogeny of the Prostigmata remains poorly known. Six major groups ('cohorts' or 'supercohorts') were recognised in the Prostigmata by Walter et al. (2009), but Dabert et al. (2010) found in their (admittedly somewhat preliminary) molecular analyses that relationships between the groups were not stable with regard to analysis method. These groups are the Labidostomatidae, Eupodides, Anystina, Parasitengonina, Raphignathina and Heterostigmatina. The Labidostomatidae are a small group of heavily armoured predatory mites with chelate chelicerae, found living on or in soil or leaf litter. The other groups, in contrast, are all more diverse.

Bdellid mite feeding on a psocodean, photographed by John J. Kent.

The Eupodides are mostly soft-bodied forms with striated integument. Most have a pair of specialised sensory setae called bothridia on the prodorsum, but these are missing in the Eriphyoidea and the marine Halacaroidea. The snout mites of the Bdelloidea are predatory mites with the chelicerae extended into an elongate proboscis; other members of the Eupodides include plant-feeders, fungivores and parasites.

Rake-legged mite Microcaeculus, photographed by Walter P. Pfiegler.

The Anystina are mostly predatory mites; some species of the families Caeculidae and Anystidae are relatively large, over a millimetre in length. Most Anystina, as well as members of the Parasitengonina and Raphignathina, have the pedipalp developed into what is called a 'thumb-claw process': the tarsus of the pedipalp is offset on the tibia, which has a terminal claw-like seta (sometimes more than one). The tibial 'claw' and the tarsus work together for grasping prey. The Caeculidae, rake-legged mites, are currently particular favourites of mine as my colleagues and I are currently in the process of preparing a description of a new species of one. These heavily sclerotised mites have a double ventral row of large spine-like setae on the forelegs; they sit in place with the forelegs raised until a springtail or some other small animal walks underneath them, at which point they drop the legs like a cage.

Trombidiid velvet mite taking down a micro-wasp, photographed by Jason Green.
The Parasitengonina are most notable for their complex life cycles, with parasitic larvae and free-living predatory adults. The group includes both terrestrial and aquatic species; the aquatic Hydrachnidiae are particularly diverse and often heavily armoured. Differences between larvae and adults are so great that taxonomists have often had no choice but to establish separate classifications for both, with relatively few larval 'species' as yet connected to their corresponding adults. Some of the terrestrial species are particularly large: velvet mites of the Trombidiidae may be over a centimetre in length.

Peacock mite Tuckerella, photographed by Christopher Pooley.
The Raphignathina are another ecologically diverse group: the Tetranychoidea are plant parasites, while other species are animal parasites or free-living predators. Raphignathina may be armoured or soft-bodied; the prodorsum lacks bothridial setae. Vertebrate-associated members of the Raphignathina include the Demodex mites that many people have peacefully living in their hair follicles. Other members of the Raphignathina include the Syringophilidae, bird parasites that live inside the quills of feathers, and the Cloacaridae that can be found in the mucous membranes of a turtle's cloaca.

Broad mite Polyphagotarsonemus latus, from here. Note the oddly stick-like modified hind legs, which are used by the male to carry larval females until they moult to maturity, as also done by the Scutacaridae.

The unusual tracheal system of the Heterostigmatina has already been referred to; this group also includes both free-living and parasitic species, with many species found in association with insects. Most species have a dorsal covering of sclerotised plates, and the palps are often greatly reduced. Heterostigmate mites described in previous posts are the Pygmephoroidea and Acarophenax.

REFERENCES

Dabert, M., W. Witalinski, A. Kazmierski, Z. Olszanowski & J. Dabert. 2010. Molecular phylogeny of acariform mites (Acari, Arachnida): strong conflict between phylogenetic signal and long-branch attraction artifacts. Molecular Phylogenetics and Evolution 56: 222-241.

Walter, D. E., E. E. Lindquist, I. M. Smith, D. R. Cook & G. W. Krantz. 2009. Order Trombidiformes. In: Krantz, G. W., & D. E. Walter (eds) A Manual of Acarology, 3rd ed., pp. 233-420. Texas Tech University Press.

Prototaxites Revisited

Reconstruction of Prototaxites by Richard Bizley, used with permission.

Richard Bizley has been kind enough to allow me to reproduce the above painting, which he produced in response to the discussion arising from an earlier post at this site. It shows a 'forest' (for want of a better word) of the enigmatic Silurian-Devonian organism Prototaxites reconstructed as a giant fungus. Richard has asked if anyone has any comments to make on the final product. Is this environment plausible? Could Prototaxites have grown in clusters like this, or would nutrient restrictions been such as to prevent such large organisms from persisting in close proximity to each other?

Since I produced my earlier post on the possible re-interpretation of Prototaxites as representing rolled ground-cover mats (Graham et al. 2010a), the proposal has been criticised in print by Boyce and Hotton (2010) and Taylor et al. (2010), and defended by Graham et al. (2010b). Boyce and Hotton regard it as taphonomically implausible that such rolls could form, while Taylor et al. also point out that the major tubes making up Prototaxites are arranged longitudinally down the 'trunk', not radiating outwards. Graham et al. have pointed out how they feel this is not incompatible with their liverwort mat hypothesis.

Colour-enhanced cross-section of Prototaxites specimen, from Graham et al. (2010b). Note that the 'growth rings' are not regularly concentric.

Prototaxites, it should be pointed out, was just one of a number of Silurian-Devonian organisms called nematophytes. Nematophytes are united by their similar internal structure, composed of hypha-like tubes. However, other nematophytes did not have the gigantic columnar form of Prototaxites: Nematothallus, for instance, was an encrusting lichen-like form, while Nematasketum fossils are only a couple of centimetres in size. Edwards and Axe (2012) have recently published a study on Nematasketum and supported comparisons between nematophytes and fungi. In particular, they compare Nematasketum to root-like anchoring and foraging structures called rhizomorphs produced by some large modern basidiomycetes. Hillier et al. (2008) nominated Prototaxites as potentially connected to root-like casts found in the Anglo-Welsh Old Red Sandstone, but admitted that the grounds for connection were slight.

REFERENCES

Boyce, C. K., & C. L. Hotton. 2010. Prototaxites was not a taphonomic artifact. American Journal of Botany 97 (7): 1073.

Edwards, D., & L. Axe. 2012. Evidence for a fungal affinity for Nematasketum, a close ally of Prototaxites. Botanical Journal of the Linnean Society 168: 1-18.

Graham, L. E., M. E. Cook, D. T. Hanson, K. B. Pigg & J. M. Graham. 2010a. Structural, physiological, and stable carbon isotopic evidence that the enigmatic Paleozoic fossil Prototaxites formed from rolled liverwort mats. American Journal of Botany 97 (2): 268-275.

Graham, L. E., M. E. Cook, D. T. Hanson, K. B. Pigg & J. M. Graham. 2010b. Rolled liverwort mats explain major Prototaxites features: response to commentaries. American Journal of Botany 97 (7): 1079-1086.

Hillier, R. D., D. Edwards & L. B. Morrissey. 2008. Sedimentological evidence for rooting structures in the Early Devonian Anglo-Welsh Basin (UK), with speculation on their producers. Palaeogeography, Palaeoclimatology, Palaeoecology 270 (3-4): 366-380.

Taylor, T. N., E. L. Taylor, A.-L. Decombeix, A. Schwendemann, R. Serbet, I. Escapa & M. Krings. 2010. The enigmatic Devonian fossil Prototaxites is not a rolled-up liverwort mat: comment on the paper by Graham et al. (AJB 97: 268–275). American Journal of Botany 97 (7): 1074-1078.

The Wracks

Bladder wrack Fucus vesiculosus, from here.

'Wrack' is one of those lovely old-fashioned words that doesn't get used anywhere near as often as it deserves. As well as being an alternative for the word 'wreck' (such as in The Wrack of Hesperus), it refers to a number of larger brown seaweeds, including the subjects of today's post, the Fucaceae.

The Fucaceae are dichotomously branching seaweeds mostly found in the intertidal zone. They vary in size from smaller forms growing higher in the littoral zone (such as the 15-cm-or-less Pelvetia fastigiata) to quite large forms growing lower down (the mid-littoral Ascophyllum nodosum may have fronds two metres in length). Fucaceae are distinguished from other families of brown algae by features such as their well-defined apical and marginal receptacles, and the single four-sided apical cell on each frond (Cho et al. 2006). Fucaceae also differ from some other brown algae in lacking a free-growing haploid stage in their life cycle: haploid cells do undergo a few rounds of post-meiotic mitosis within the receptacles, but are released as individual eggs and sperm that immediately fuse to found the diploid generation.

With the removal of the Australasian Xiphophoraby Cho et al. (2006), the Fucaceae has become a strictly Northern Hemisphere family. This is interesting because the larger clade of the Fucales to which the Fucaceae belong is mostly Southern Hemisphere in diversity. Representatives of the Fucaceae are found both in the Pacific and the Atlantic, with a distinct flora in each (only a single species, Fucus distichus, is believed to be native to both oceans, though some would separate the Pacific population as F. gardneri). Cánovas et al. (2011) favoured a Pacific origin for the Fucaceae, on the grounds that this provided the most intuitive biogeographical connection to the related Australasian taxa Xiphophora and Hormosira, but parsimony analysis alone was unable to confirm or deny this scenario. Basal clades within the family include representatives in both oceans.

The North Pacific Silvetia compressa, photographed by James Watanabe.

Though currently divided between six genera, the family is not speciose, and only two of those genera include more than a single species: the Pacific Silvetia (three species; previously included in Pelvetia but removed by Serrão et al. 1999 on the grounds of non-monophyly) and the mostly Atlantic Fucus (eight[?] species). The clade may be fairly recent in origin: though estimating an age is complicated by the relatively poor fossil record of brown algae, Cánovas et al. (2011) estimated with molecular dating that the Fucaceae diverged in the mid to late Miocene, with their ancestors possibly crossing the equator as Australia moved north. Complicating matters, species of Fucaceae can be morphologically very variable: in the 1960s, for instance, H. T. Powell revised the 100+ species, varieties and forms then recognised within Fucus down to only six species (Serrão et al. 1999). These species can be divided between a northern, specifically cold-water clade with the rockweed Fucus distichus and the toothed wrack F. serratus, and a more warm-water-tolerant clade containing the remaining species (Cánovas et al. 2011). These species tend to be ecologically distinct, each preferring slightly different microhabitats within the littoral zone, but they can hybridise where they come into contact and reproductive isolation is probably not complete (Zardi et al. 2011). Two further species of Fucus have been recognised recently: F. guiryi is a north-eastern Atlantic species previously recognised as F. spiralis var. platycarpus (Zardi et al. 2011; the name 'Fucus platycarpus' cannot be used for this species owing to homonymy), while F. radicans is a species unique to the relatively low-salinity Baltic Sea (Bergström et al. 2005). All indications are that Fucus radicans is a recent segregate from the more widespread bladder wrack F. vesiculosus, which is also the only other Fucus species found in the Baltic. The Baltic Sea itself is not, in its current form, very old, and molecular data suggest that the divergence of F. radicans may have only happened within the last four hundred years (Pereyra et al. 2009).

Knotted wrack Ascophyllum nodosum, from Fisheries and Oceans Canada.

REFERENCES

Bergström, L., A. Tatarenkov, K. Johanneson, R. B. Jönsson & L. Kautsky. 2005. Genetic and morphological identification of Fucus radicans sp. nov. (Fucales, Phaeophyceae) in the brackish Baltic Sea. Journal of Phycology 41: 1025-1038.

Cánovas, F. G., C. F. Mota, E. A. Serrão & G. A. Pearson. 2011. Driving south: a multi-gene phylogeny of the brown algal family Fucaceae reveals relationships and recent drivers of a marine radiation. BMC Evolutionary Biology 11: 371.

Cho, G. Y., F. Rousseau, B. de Reviers & S. M. Boo. 2006. Phylogenetic relationships within the Fucales (Phaeophyceae) assessed by the photosystem I coding psaA sequences. Phycologia 45 (5): 512-519.

Pereyra, R. T., L. Bergström, L. Kautsky & K. Johannesson. 2009. Rapid speciation in a newly opened postglacial marine environment, the Baltic Sea. BMC Evolutionary Biology 9: 70.

Serrão, E. A., L. A. Alice & S. H. Brawley. 1999. Evolution of the Fucaceae (Phaeophyceae) inferred from nrDNA-ITS. Journal of Phycology 35: 382-394.

Zardi, G. I., K. R. Nicastro, F. Canovas, J. Ferreira Costa, E. A. Serrão & G. A. Pearson. 2011. Adaptive traits are maintained on steep selective gradients despite gene flow and hybridization in the intertidal zone. PLoS One 6 (6): e19402.

The Dilleniaceae: Tropical Enigmas

Flower and opened fruit of the 'red beech', Dillenia alata, from here.

In recent years, molecular analyses of often very large data sets have given us a reasonably good picture of the evolution of flowering plants, with most higher taxa settling down to reasonably comfortable positions. The subject of today's post, however, is still something of a phylogenetic enigma.

The Dilleniaceae are a family of about 500 species found mostly in the tropics, though one genus, Hibbertia, is also diverse in temperate Australia. Members of the family are very diverse in appearance: though the majority are trees or shrubs, some are lianes or even herbs. Dilleniaceae also show a remarkable diversity in features that are relatively stable in other families, such as floral symmetry and merosity (the number of flower organs such as stamens or carpels) (Horn 2009). Despite this diversity, Dilleniaceae are constant enough in other features that they have been recognised as a unified group since at least the 1800s. More questionable is their relation to other flowering plants: they are certainly members of the Pentapetalae, but the presence in some species of seemingly 'basal' characters (such as ladder-like perforation plates in the xylem and leaves with disorganised venation) lead some authors to regard them as an evolutionary link between the more basal magnoliids and a group of pentapetalous plants with centrifugal (starting from the centre and moving outwards) stamen development, called the Dilleniidae. 'Dilleniids' are now recognised as polyphyletic, including members of both the major clades Rosidae and Asteridae, but the Dilleniaceae themselves are not well resolved beyond basal Pentapetalae. Soltis et al. (2011) recently placed the Dilleniaceae as related to the clade of Asteridae + Caryophyllales + Santalales, but other analyses have placed them closer to Rosidae + Saxifragales, or even sister to all other Pentapetalae. Just to confuse matters, phylogenetic analysis within the Dilleniaceae suggests that at least some of their 'primitive' characters are in fact derived reversals of specific subtaxa (Horn 2009).

Erect guinea-bush Hibbertia riparia, photographed by Williewonker.

Relationships within the Dilleniaceae are perhaps better understood. The pantropical genus Tetracera was placed by horn (2009) as the sister to all other Dilleniaceae, which are divided between a strictly Neotropical clade (the Doliocarpoideae) and a strictly Old World clade. The Old World clade is in turn divided between two biogeographically distinct subclades, one centred in southern Asia (the Dillenioideae) and the mostly Australasian genus Hibbertia. Hibbertia and the Dillenioideae overlap only in northernmost Australia, southern New Guinea, Fiji and Madagascar (where both Dillenia and Hibbertia have representatives on the eastern side of the island). The Neotropical Doliocarpoideae are mostly lianes or scandent shrubs, with the only tree being the savannah species Curatella americana. The liane form is much rarer among Old World Dilleniaceae, most of which are trees or shrubs, though the small southern Asian genus Acrotrema contains rhizomatous herbs (and may be phylogenetically within the genus Dillenia). A group of succulent Australian species with photosynthetic stems, previously recognised as the genus Pachynema, have been reclassified by Horn (2009) as a derived subgroup of Hibbertia.

Hibbertia juncea, previously Pachynema junceum, photographed by Russell Cumming.

REFERENCES

Horn, J. W. 2009. Phylogenetics of Dilleniaceae using sequence data from four plastid loci (rbcL, infA, rps4, rpl16 intron). International Journal of Plant Sciences 170 (6): 794-813.

Soltis, D., E., S. A. Smith, N. Cellinese, K. J. Wurdack, D. C. Tank, S. F. Brockington, N. F. Refulio-Rodriguez, J. B. Walker, M. J. Moore, B. S. Carlsward, C. D. Bell, M. Latvis, S. Crawley, C. Black, D. Diouf, Z. Xi, C. A. Rushworth, M. A. Gitzendanner, K. J. Sytsma, Y.-L. Qiu, K. W. Hilu, C. C. Davis, M. J. Sanderson, R. S. Beaman, R. G. Olmstead, W. S. Judd, M. J. Donoghue & P. S. Soltis. 2011. Angiosperm phylogeny: 17 genes, 640 taxa. American Journal of Botany 98 (4): 704-730.

A New Short-horned Elasmus

Female Elasmus curticornis Gunawardene & Taylor 2012, newly out today!

I can now officially claim not to be a one-trick pony: my first non-harvestman academic paper has just been published. The paper, "New records of Elasmus (Hymenoptera, Eulophidae) species from Barrow Island, Western Australia", written with my co-worker Nihara Gunawardene, is freely available from the Journal of Hymenoptera Research.

Elasmus is a particularly attractive genus of chalcid micro-wasps that can be immediately distinguished from most other chalcids by their massively enlarged hind coxae, which are shaped like discs, and their long wedge-shaped wings. The Elasmus species of Australia were reviewed by Riek (1967), but most of them were known only from a small number of localities, mostly on the eastern side of the continent. In the course of going through material collected on Barrow Island, Nihara and I identified several species of Elasmus that had not been previously recorded from north-west Australia, and our new paper is mostly a record of those range extensions. Also, as most of the species had never actually been illustrated before, we provided extensive colour specimen photographs.

Elasmus ero emma, from Gunawardene & Taylor (2012).

Among the specimens, though, were a couple that we couldn't quite match up with any of the species in Riek's paper. They jumped between a few different identifications, but none of them really worked. So we had to broaden our comparisons: a bit of a daunting prospect, may I note, because Elasmus has over 200 species worldwide and I wasn't really keen on the idea of checking every single one of them to see whether they were the species we had on hand. As it turned out, I needn't have worried: the unusually short antennae of this species eliminated all but a few options. And after striking out those options as well, we prepared a description of a new species: Elasmus curticornis Gunawardene & Taylor 2012.

The species name means 'short-horned', in reference to the short antennae, and also in reference to one of the other similar species, E. brevicornis, which has an extensive distribution in Eurasia. I did spend a few days pondering whether our specimens might be slightly unusual examples of E. brevicornis: the most obvious difference between the two is that E. curticornis has a much more extensive area of orange on the gaster than has E. brevicornis. Eventually, we decided to go with declaring a new species, and at least none of the reviewers shot us down. I'm still keeping an eye out for more specimens to test our identification, but it doesn't seem to be a very abundant species so far.

Elasmus auratiscutellum, photographed by yours truly.

REFERENCES

Riek, E. F. 1967. Australian Hymenoptera Chalcidoidea family Eulophidae, subfamily Elasminae. Australian Journal of Zoology 15: 145–199.

The Anchisaurs: Near-lizards or Near-sauropods?

Reconstruction of Anchisaurus polyzelus by Brian Franczak.

The 'prosauropods' are one group of dinosaurs that seemingly don't get no respect. While most other groups have their swarms of enthusiasts, there are relatively few inclined to shout their enthusiasm for non-sauropod sauropodomorphs from the roof-tops. Pop culture has a tendency to gloss them over: in the 1990s TV series Walking with Dinosaurs, for instance, their appearance was limited to a brief cameo at the end of the first episode. Despite this, they are perhaps the most 'dinosaur-y' of all dinosaurs, if comparisons with generic 'dinosaur' depictions are to be made.

The name 'Anchisauria' was introduced by Galton & Upchurch (2004) for the most exclusive clade uniting the genera Anchisaurus and Melanorosaurus. Galton & Upchurch were working under the framework that prosauropods formed a monophyletic sister group to the sauropods, but subsequent phylogenetic analyses have placed sauropods close to Melanorosaurus and hence within Anchisauria (Yates 2010; Yates et al. 2010; Pol et al. 2011). The name 'Anchisauria' can be translated as 'near lizards', but they are more properly near sauropods. Still, because this is to be a prosauropod-centred post, I will ignore the sauropods from this point on unless they insist on pushing their way in (presumably not a difficult task for a sauropod).

Reconstruction of Aardonyx celestae by Julius Csotonyi.
The two anchoring genera remain the most consistent non-sauropod members of the clade. The South American Riojasaurus, placed within Melanorosauridae by Galton & Upchurch (2004), has subsequently been placed outside Anchisauria. The Argentinian Lessemsaurus was also treated by those authors as a melanorosaurid, but may be a basal sauropod proper, while the status of the English Camelotia needs more work (Pol et al. 2011 were unable to resolve its position between Anchisauria and its close relatives). The Chinese Yunnanosaurus was placed within Anchisauria by Yates (2010), but other analyses have disagreed. Two recent genera, Aardonyx Yates et al. 2010 and Leonerasaurus Pol et al. 2011 are currently regarded as anchisaurians.

Mounted skeleton of Leonerasaurus taquetrensis, from here. Note that a large part of this skeleton is evidently reconstructed, as the described skeleton is much more fragmentary.

Anchisaurus polyzelus, from the early Jurassic of Connecticut, reached about four metres in length and is represented by the remains of a number of individuals. Some of these have been described as separate species such as Ammosaurus major and Yaleosaurus colurus, but Yates (2010) regarded them as representing a single species. This makes the '2.5 m' estimate of length given for this species by Galton & Upchurch (2004) too small, as based on a potential juvenile. Nevertheless, it was evidently such a good number that the fossil record apparently decided not to let it pass: the Argentinian anchisaur Leonerasaurus taquetrensis is about that size. The South African Aardonyx celestae was probably comparable to size to Anchisaurus* [Update: Spectacular reading fail on my part. A. celestae was about twice the size of Anchisaurus. See comments below].

*Actually, the scale bar given for the skeletal reconstruction of A. celestae by Yates et al. (2010) would seem to indicate that is must have been the smallest sauropodomorph ever. One can only assume that its size was meant to indicate 500 mm, not '500 µm' [Update: Ignore this. I am a twit. See comments below].

Reconstruction of Melanorosaurus readi, by Steveoc 86. Note that the four species illustrated in this post have been placed in order of increasing proximity to Sauropoda, as resolved by Pol et al. (2011).

Melanorosaurus readi was quite a bit larger, close to eight metres, and phylogenetic analyses have accordingly placed it as the closest relative to sauropods. Interestingly, M. readi was nevertheless quite a bit earlier than the other non-sauropod anchisaurs, being late Triassic rather than early Jurassic, and the smaller anchisaurs evidently survived the evolution of their larger cousins by some time. As well as its larger size, M. readi resembled sauropods in being an obligate quadruped. The other anchisaurs retained their plesiomorphic bipedality; the forelimbs of Aardonyx indicate that it was probably unable to adopt a comfortably quadrupedal stance (being unable to pronate its hands to a great degree, it would have had to rest them on their sides if it tried to do so). Pol et al. (2011) placed Leonerasaurus closer to the sauropods and Melanorosaurus than either Anchisaurus or Aardonyx, but the distal part of its forelimbs are unfortunately unknown.

REFERENCES

Galton, P. M., & P. Upchurch. 2004. Prosauropoda. In: Weishampel, D. B., P. Dodson & H. Osmólska (eds) The Dinosauria, 2nd ed., pp. 232-258. University of California Press.

Pol, D., A. Garrido & I. A. Cerda. 2011. A new sauropodomorph dinosaur from the Early Jurassic of Patagonia and the origin and evolution of the sauropod-type sacrum. PLoS One 6 (1): e14572.

Yates, A. M. 2010. A revision of the problematic sauropodomorph dinosaurs from Manchester, Connecticut and the status of Anchisaurus Marsh. Palaeontology 53 (4): 739-752.

Yates, A. M., M. F. Bonnan, J. Neveling, A. Chinsamy & M. G. Blackbeard. 2010. A new transitional sauropodomorph dinosaur from the Early Jurassic of South Africa and the evolution of sauropod feeding and quadrupedalism. Proceedings of the Royal Society of London Series B—Biological Sciences 277: 787-794.

Hemiaster: An Echinoid with Heart

The Upper Cretaceous Hemiaster (Hemiaster) bufo, in (a) aboral, (b) oral, (c) lateral and (d) posterior view. From Fischer (1966).

For today's post subject, I've drawn the echinoid genus Hemiaster. Hemiaster is a member of the group of echinoids known as heart urchins, in reference to their overall shape when viewed from above. Species of Hemiaster are also fairly deep, so their overall shape when viewed from the side is somewhat reminiscent of a hoof. Heart urchins mostly live burrowed into sediment (mud, in the case of Hemiaster). One notable feature compared to other echinoids is that they have lost the Aristotle's lantern, the 'jaw' structure found in regular echinoids. Heart urchins are detritivores feeding on organic matter either buried in sediment or deposited on the surface of their substrate. The specific habits of living Hemiaster species seem to be poorly known, due to their living in deep-water habitats, but an Atlantic specimen of H. expergitus has been found living in a 12 cm deep burrow with a narrow funnel opening to the surface (Gage 1987).

In order to maintain their burrows, heart urchins have exceedingly long and well-developed tube feet, the openings for which in the test are visible as a petal-shaped pattern (and I must expose my ignorance, here: before I started looking up stuff for this post, I had always assumed that the petaloid pattern on heart urchins was on the underside. It is, in fact, on the aboral side). Also characteristic of heart urchins are fascioles, bands of closely-crowded tiny spines covered with cilia, that are believed to function in respiration by increasing water flow over themselves (a necessary process when the respiratorily available surface of the animal has been mostly buried by mud) (Fischer 1966). In Hemiaster, the only fasciole present runs around the space occupied by the petaloids; other heart urchins may have different patterns of fascioles on different parts of the body.

Cretaceous Hemiaster whitei, from here.

Fossils attributed to Hemiaster date back as far as the Cretaceous, and it appears to be better known as a fossil than a living animal. This is not entirely unusual for echinoderms: I have a vague recollection of Chris Mah, who works on living echinoderms, complaining about this very point, but I can't recall exactly where/when he did so (sorry, Chris!). Still, in some justification, Hemiaster was more diverse in the past than it is now: of the seven subgenera recognised in Hemiaster by Fischer (1966), only the nominotypical subgenus survives to the present, and none of the others postdates the Palaeocene.

REFERENCES

Fischer, A. G. 1966. Spatangoids. In: Moore, R. C. (ed.) Treatise on invertebrate Paleontology pt U. Echinodermata 3 vol. 2, pp. U543-U628. The Geological Society of America, Inc., and The University of Kansas Press.

Gage, J. D. 1987. Growth of the deep-sea irregular sea urchins Echinosigra phiale and Hemiaster expergitus in the Rockall Trough (N.E. Atlantic Ocean). Marine Biology 96: 19-30.

O Zoobank, Where Art Thou?

Does anyone reading this have experience with registering publications, etc. on ZooBank? Can you clarify how the process works?

In the comments for yesterday's post, two readers brought up a potential issue with ZooBank's records. A number of taxa published recently in PLoS One that were supposed to have been registered with ZooBank, such as Mochlodon vorosi, are not coming up in searches there. However, the original publications for these taxa cite LSIDs, the unique identifier assigned to any ZooBank registration, for them. If these taxa were never registered with ZooBank, how could there have been an LSID to cite? I ran a search of my own for two taxa recently published in a different journal, ZooKeys: Calliostoma tupinamba and Angelopteromyia korneyevi. Same result: cited LSIDs, but no results in a ZooBank search.

So what's happening here? If a paper is registered prior to being published (as must have been the case here, for the LSID to be cited in the published papers), does the registrant have to confirm publication later for that record to be visible to the public? Could these records have simply not yet been made public? Or is there a bigger problem here?

The ICZN and Electronic Publication: Where Did It Go Wrong?

Reconstruction of the dinosaur Aerosteon riocoloradensis, from here. This species was published in electronic-only format in September 2008; it was nearly six months before anyone noticed that this was a problem.

Since the ICZN approved electronic publication, we've had a few weeks to get over the initial heady rush of excitement and further assess the situation. Which means that we have to ask the question: what is wrong with the new rules?

There is no question that some of the new rules on electronic publication will need to be adjusted. This, I hasten to point out, is not an indictment. The International Code of Zoological Nomenclature for dealing with paper publications first appeared over fifty years ago, in 1961, and the earliest attempt at a formal code of nomenclature had been proposed by Hugh Edwin Strickland another 120 years before that. Despite all this time, the Code as it pertains to paper publications has still not been perfected, and revisions continue to be proposed and published. Indeed, some of the issues the code grapples with (such as what does or does not constitute 'publication') are, in the end, probably not universally soluble, because they deal with factors such as judging ethical behaviour that cannot be expressed in simple formulae applicable to every situation. So it should hardly be expected that rules for electronic publication should have immediately attained perfection when not even those for paper publication, with 170 years or more of a head start, have not yet done so. What is more, some of the failings in the current rules will not become apparent until they are able to be tested. Loopholes will have to be closed, terms will have to be clarified. And as I airily critique issues with the current rules in this post, I am well aware that the rules' composers will have probably already discussed them to death, and any suggestions I make may have their own problems that I have overlooked.

What, exactly, is an electronic publication?

As I noted in the earlier post linked to above, the ICZN effectively requires that any electronic publication has an associated ISBN or ISSN (this does not have to appear in the publication itself, but it is required for the registration of the publication on ZooBank). To a certain extent, this makes sense: it means, for instance, that taxonomists do not have to worry about taxa being 'accidentally' published in mailing groups, blogs, etc. that may not be reliably archived. But it does raise the question: in the electronic age, why should a publication necessarily be a 'book' or a 'serial'?

The ICN (International Code for Nomenclature of plants, algae and fungi; what we used to call the ICBN) apparently requires that electronic publications be in pdf format. The ICZN does not make this an actual requirement, though pdf is cited as an example of a format that meets the requirement of 'widely accessible electronic copies with fixed content and layout'. I think that the ICZN is in the right here; while it is difficult to see pdf being superseded at the present point in time, it is perhaps hazardous to assume that this will never happen. I suggest that the requirements of an electronic publication should be that, (A) at least the content (if not the format) should be intended to be immutable*, and (B) it should be somehow 'stand-alone', not requiring a larger context other than the standard requirements for reading electronic files (so, for instance, a database entry that can only be accessed as part of that database may not be acceptable).

*It is worth noting at this point that even a paper publication is, in a sense, not 'immutable' if its publishers do not behave ethically. If a publisher produces a second, altered print run without explicitly marking it as a revised edition or changing the reported publication date, there may be no indication that it represents a distinct publication from the original run. Most people will not read through two separate copies of a publication just on the off-chance that they may differ.

Do pre-releases count?

There is one clause in the new rules that I expect will be guaranteed to cause immediate problems. This is the new Article 21.8.3: "Some works are accessible online in preliminary versions before the publication date of the final version. Such advance electronic access does not advance the date of publication of a work, as preliminary versions are not published (Article 9.9)."

Remember old Scansoriepidendrosauropteryx? This was an animal that first debuted in an electronic online-early form in a well-known journal, but before the print edition of that paper was finally published the animal was described under a different name in a paper-only publication. The resulting confusion, when the earliest name publicised was not the one with technical priority, was one reason why at least some people were calling for electronic publication to be recognised. Well, guess what? Under the current rules, this case would have played out no differently. Some would look askance at accepting pre-releases as validly published because of the possibility of alteration between the pre-release and the final edition, but as I said above, perhaps this is something that requires us to discuss what exactly we regard as a 'publication'.

There is also the new Article 21.9 to consider: 'A name or nomenclatural act published in a work issued in both print and electronic editions takes its date of publication from the edition that first fulfilled the criteria of publication of Article 8 and is not excluded by Article 9.' Some may read this as saying that an electronic pre-release counts as a valid publication if, in itself, it meets the requirements of electronic publication. Some may read this as being trumped by 21.8.3.

And what about electronic versions of paper publications?

To be validly published, an electronic publication has to be registered with ZooBank and include evidence of its registration. Paper publications, on the other hand, do not yet have to be registered. The problem is, many researchers are now more likely to access electronic copies of paper publications than the original paper edition itself. And if I do so, how can I be sure that the paper edition actually exists? Even for some of my own publications in recent years, I've never actually laid eyes on the original journals. I've only seen the pdfs, and I've trusted in the publisher that the paper edition exists and that taxa I've erected are indeed validly published. Similarly, if I come across a publication from an unfamiliar journal (and with hundreds if not thousands of journals publishing in biology worldwide, I will not be familiar with them all) when searching online, would I necessarily know whether that represents an electronic-only publication or an electronic copy of a paper one?

When the question of electronic publication was still being debated, I stated more than once that the biggest problem with not accepting it was that, for many readers, it was all too difficult to distinguish valid publications from invalid. I have my doubts whether this problem has yet been solved.

Asperdaphne, I Don't Know Who You Are Any More

A true Asperdaphne: the type species A. versivestita, photographed by Des Beechey.

The subject of today's post has been going through something of an identity crisis recently. Asperdaphne was listed by Powell (1966) as a genus of small conoid gastropods found in Australia, New Zealand and the Pacific coast of Asia, with a fusiform shell and coarse clathrate (lattice-like) ornamentation. This remains the sense in which it has been most commonly recognised. However, in a paper published just last year, Beu (2011) revealed that this picture of Asperdaphne was a fraud. The majority of species assigned to Asperdaphne by Powell (1966) were not members of the same genus as the type, A. versivestita. Instead, they belonged to another genus, Pleurotomella, the type species of which Powell had not been familiar with. Meanwhile, A. versivestita was more appropriately placed with what Powell had called Tritonoturris, an Indo-Pacific genus of larger conoids with a more ovate shell shape. As Asperdaphne was an older genus name than Tritonoturris, this meant that what had been Tritonoturris was now Asperdaphne, while what had been Asperdaphne was now Pleurotomella. The identity of the two east Asian species assigned to Asperdaphne by Powell (1966) was not discussed by Beu (2011).

Not an Asperdaphne: Pleurotomella hayesiana, also photographed by Des Beechey.

We have encountered this paper of Beu's before, when I cited it in the post on another conoid genus, Kuroshioturris. As with that genus, the recognition of Asperdaphne had been confused by differences in protoconch morphology related to larval nutrition. Species assigned to 'Tritonoturris' had a tall conical protoconch, indicating a planktotrophic (feeding on plankton) lifestyle as a larva, while Asperdaphne versivestita has a blunt-tipped paucispiral protoconch, indicating that its larvae are lecithotrophic ('fed' by energy reserves in the yolk).

Diagram of the foregut of 'Tritonoturris' subrissoides, from Fedosov (2008).

Slightly more mysterious are Asperdaphne's feeding habits as adults. Foregut structure has been investigated for one presumed Asperdaphne species, under the name Tritonoturris subrissoides (Fedosov 2008). T. subrissoides is one of a number of members of the family Raphitomidae to show a reduction in foregut structures, and has lost the radula and venom gland of most conoids. Instead, it has a large introvert (extendable proboscis) that probably functions in prey capture. However, the roof of the introvert has a large and elongate outgrowth, unlike any found to date in any other conoid, with a well differentiated muscle system indicating that it is capable of complex movement. Presumably, this outgrowth functions somehow in prey capture (perhaps as a grasping 'finger'?) but its exact purpose remains unknown.

REFERENCES

Beu, A. G. 2011. Marine Mollusca of isotope stages of the last 2 million years in New Zealand. Part 4. Gastropoda (Ptenoglossa, Neogastropoda, Heterobranchia). Journal of the Royal Society of New Zealand 41 (1): 1-153.

Fedosov, A. E. 2008. Reduction of the alimentary system structures in predatory gastropods of the superfamily Conoidea (Gastropoda: Neogastropoda). Doklady Biological Sciences 419: 136-138.

Powell, A. W. B. 1966. The molluscan families Speightiidae and Turridae: an evaluation of the valid taxa, both Recent and fossil, with lists of characteristic species. Bulletin of the Auckland Institute and Museum 5: 1-184, pls 1-23.