Sunorfa

The Queensland pselaphine Sunorfa nigripes, from Chandler (2001).

When I began researching the taxon that was to be the subject of this post, I was surprised to discover that it had weaseled its way onto this site once before. Back in the day, I used an example of the beetle genus Sunorfa to illustrate a post about a closely related genus for which I had been unable to find an image (before a reader pointed me in the direction of one). Sunorfa is a member of that wonderful group of miniature gargoyles, the Pselaphinae (I had the pleasure/pain of sorting a handful of pselaphines at work just the other week; their minute size [usually only a millimetre or two long] makes them a real challenge to work with but their bizarre morphologies make it impossible to resent them). Most species of Sunorfa are found in tropical rainforest litter in southern Asia and Australasia from Sri Lanka to Fiji with the highest diversity of species in New Guinea. In addition, a handful of species are found in the Seychelles. I haven't come across any direct indication of what Sunorfa are doing in all these places but presumably, like other pselaphines, they are predators of even smaller arthropods.

Distinctive features of Sunorfa compared to other pselaphines include a strong transverse sulcus (groove) across the rear part of the pronotum, and a cylindrical abdomen in which the upper tergites and lower sternites are fused into single continuous rings. They also have characteristic foveae (deep depressions) on the top of the head, the base of the elytra including on each side at the 'shoulders', and in the middle of the metasternum (the rear underside section of the thorax) (Chandler 2001). Similar foveae are found in one form or another, in one place or another, on most pselaphines. They have received a lot of attention in taxonomic studies (their appearance and distribution is one of the most reliable features in distinguishing pselaphine taxa) but their function is less well known. Chandler (2001) expressed the opinion that foveae in different parts of the body serve different purposes. Those on the thorax have solitary, sensilla-like setae at their centres and probably represent sensory structures of some kind. Conversely, foveae on the head and abdomen lack such setae and commonly connect to one another internally to form solid tubes. These tubes may function as struts, providing the body with rigidity and strength as the animal is reduced down in size.

REFERENCE

Chandler, D. S. 2001. Biology, morphology, and systematics of the ant-like litter beetle genera of Australia (Coleoptera: Staphylinidae: Pselaphinae). Memoirs on Entomology, International 15: 1–560.

All that is Silver is not Fish

Common silverfish Lepisma saccharina, copyright Christian Fischer.

The insects are deservedly recognised as one of the most successful groups of organisms on the planet. Thanks in no small part to their unlocking the ability of flight, insects can be seen today in almost every part of the planet above sea level. But not all insects, of course, are flighted; many remain firmly on the ground. A large proportion of these are the descendents of flighted ancestors that returned to a terrestrial existence but there are also some whose ancestors never took to the skies. For most people, the most familiar of these original land-huggers are likely to be the silverfish of the family Lepismatidae.

Silverfish are long-bodied insects with a covering of reflective scales—hence the 'silver' part of their name. The 'fish' part probably refers to the manner of their movement; speaking from my own experience collecting them, these buggers move fast, slipping along the ground like a silver minnow. There are over 250 known species of Lepismatidae (Mendes 2002); probably many more remain to be described. They comprise over half the known species of the insect order Zygentoma (sometimes referred to as the Thysanura though most current entomologists tend to avoid that name due to its previous history referring to a now-obsolete grouping of the Zygentoma with the superficially similar Archaeognatha); the other families in the order are commonly subterranean and less commonly encountered by the average person. The highest diversity of silverfish occurs in tropical and subtropical parts of the world, particularly in arid or semi-arid regions. Adaptations of the rectal epithelium allow silverfish to absorb moisture straight from the atmosphere (or, to put it another way, they drink through their butt), making them ideally suited to tolerating the dryness of deserts. They are also suited to tolerating the relatively dry habitats offered by the interiors of human houses and several species have become our associates (in cooler parts of the world, these synathropic species are often the only lepismatids around). These include the common silverfish Lepisma saccharina and the giant silverfish Ctenolepisma longicaudata. The firebrat Thermobia domestica is a colourfully patterned human associate that likes it particularly warm; it is usually restricted to places like the backs of stoves or alongside hot-water cylinders where it can find the heat it craves. Being detritivores (that is, they feed on dust), human-associated silverfish are usually quite innocuous though they may cause problems if their numbers get too high or if they get into stored foodstuffs.

Firebrat Thermobia domestica, copyright David R. Madison.

In areas where they are native, silverfish may be quite diverse. Watson & Irish (1998) conducted a study of an area of the Namib Desert that was home to eight different species of silverfish. They found a tendency for the species to differ in their preferred microhabitat within the area: some were restricted to the upper parts of the sand dunes dominating the region, others were restricted to the rocky hollows separating the dunes. Those found in rocky lower zones resembled the familiar human-associated species (indeed, they included members of the same genus as the giant silverfish, Ctenolepisma) in being elongate and slender. In contrast, those species found higher in the dunes themselves were shorter and more flattened with well-developed spines covering the legs. These features allowed the dune silverfish to effectively 'swim' through the sand, using the spines on the legs to dig about and their flattened form to slip between grains.

REFERENCES
Mendes, L. F. 2002. Taxonomy of Zygentoma and Microcoryphia: historical overview, present status and goals for the new millennium. Pedobiologia 46: 225–233.

Watson, R. T., & J. Irish. 1998. An introduction to the Lepismatidae (Thysanura: Insecta) of the Namib Desert sand dunes. Madoqua 15 (4): 285–293.

Forams with Teeth

Time for another foram post. The above image (copyright Robert P. Speijer, scale bar = 100 µm) shows Turrilina brevispira, a typical Eocene representative of the foram subfamily Turrilininae.

The Turrilininae are a group of calcareous forams that first appeared in Middle Jurassic (Loeblich & Tappan 1964). In most species, the test is what is called a 'high trochospiral' form: that is, it coils in a similar manner to, and overall looks rather like, a high-shelled snail. Each of these whorls is divided into at least three successive chambers, sometimes more. At the end of the test is a loop-shaped aperture. At least one species of turrilinine, Floresina amphiphaga, is a predator/parasite of other forams, drilling into their test to extract their protoplasm.

The turrilinines are most commonly classified in a broader foram superfamily known as the Buliminoidea or Bulimnacea. Other buliminoids commonly resemble turrilinines in their overall form. The group has commonly been defined, however, on the basis of what is called a 'tooth-plate'. This is an outgrowth of the internal wall of the test that runs between the apertures of each chamber. The exact appearance of the tooth-plate differs between taxa; in Turrilina, for instance, it is a trough-shaped pillar that is usually serrated along one end (Revets 1987). I have no idea what the function of the tooth-plate is, if indeed any is known, whether it provides an anchor for some cytoplasmic structure or anything else. However, in more recent decades a number of authors have questioned whether the tooth-plate is as significant a taxonomic feature as previously thought. For instance, Tosaia is a Recent genus of foram whose overall morphology and chamber arrangement is fairly typical for the Turrilininae but which lacks any sign of a tooth-plate (Nomura 1985). Excluding Tosaia from the buliminoids on this basis alone would imply a remarkably strong evolutionary convergence of every other feature of this genus.

REFERENCES

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

Nomura, R. 1985. On the genus Tosaia (Foraminiferida) and its suprageneric classification. Journal of Paleontology 59 (1): 222–225.

Revets, S. A. 1987. A revision of the genus Turrilina Andreae, 1884. Journal of Foraminiferal Research 17 (4): 321–332.

Riding a Frog's Pouch

Most people are familiar with the concept of marsupials, the group of mammals whose young spend the earliest part of their life nurtured within a pouchon their mother's underside. Kangaroos, koalas, wombats—all have their established place in popular culture (even if a person can't really ride inside a kangaroo's pounch, and anyone trying to is likely to find themselves picking their intestines off the floor). But perhaps less people are aware that a nurturing pouch is not unique to marsupial mammals: among others, there are some frogs that do it too.

Horned marsupial frog Gastrotheca cornuta female carrying eggs, copyright Danté B. Fenolio.

The marsupial frogs are found over a great part of South America, being particularly diverse in upland regions. Many (particularly members of the genus Hemiphractus) are somewhat gargoyle-ish beasts with flattened heads and/or prominent 'horns' above the eyes. Until recently, marsupial frogs were usually classified as a subfamily of the treefrog family Hylidae but more recent phylogenetic studies have agreed on the polyphyly of the latter family in its broad sense. As a result, the marsupial frogs are now placed in their own distinct family, the Hemiphractidae, as part of a broader association of a number of South American frog families. The influential phylogenetic study of amphibians by Frost et al. (2006) suggested that the marsupial frogs themselves were polyphyletic and divided them between no less than three families (Hemiphractidae, Cryptobatrachidae and Amphignathodontidae) but more recent studies have agreed on their monophyly. Frost et al.'s results are generally thought to have resulted from their poor coverage of members of this clade.

So what makes them marsupials? In all hemiphractids, the female carries her eggs after fertilisation until they hatch. In three of the five recognised genera (Hemiphractus, Cryptobatrachus and Stefania), the eggs are carried exposed on the surface and the young hatch directly as fully-formed froglets without a free-living tadpole stage. In the other two genera, Flectonotus and Gastrotheca (the latter genus being the most diverse in the family), the eggs are contained in a pair of pouches on the female's back. In some Gastrotheca species the eggs hatch into froglets as in the other genera, but in other Gastrotheca and in Flectonotus they hatch into tadpoles that the female then releases into a suitable pool of water.

Female Spix's horned treefrog Hemiphractus scutatus carrying a load of young froglets, copyright Santiago Ron.

Considering that a tadpole stage in development is evidently the original condition for frogs as a whole, it might be assumed the tadpole-bearing hemiphractids represent the basal taxa in the group with loss of the tadpole being derived. But intriguingly, recent phylogenetic analyses have indicated that the tadpole-bearing Gastrotheca occupy quite deeply nested positions in the hemiphractid family tree (Wiens et al. 2007; Flectonotus is placed as the sister taxon of all other hemiphractids, more as one might expect). This has led to the suggestion that the presence of tadpoles in Gastrotheca may represent a reversal to the original condition from direct-developing forebears. Now, I'm going to admit up front that I tend to be skeptical about claims for the reappearance of complex characters (and only partially because such studies never fail to cite that "stick insects re-evolved wings" thing of which I've already said I'm not a fan). In their analysis of breeding trajectories in hemiphractids, Wiens et al. (2007) found that, if one assumed that loss of the tadpole stage was equally likely to its gain, then the hemiphractid phylogeny supported a re-gain of tadpoles. However, if one presumed that loss was more likely than gain, then their analysis supported multiple losses with the tadpole-bearing Gastrotheca retaining the ancestral state. Nevertheless, they argued that a re-gain was more likely. Tadpole-bearing hemiphractids are all inhabitants of high altitudes where their young are often the only tadpoles about, suggesting that competition with other frogs excludes them from lower altitudes. Assuming multiple origins of direct development would require that the low-altitude hemiphractids evolved from low-altitude tadpole-bearers of which there is no current sign. But could it be that more recent changes in the South American environment changed the competitive regime for hemiphractids? Have the frog lineages that supposedly exclude them for lower altitudes been in the area for as long as the hemiphractids have? On the other hand, hemiphractids are unusual among direct-developing frog in that their embryos still develop some tadpole-like features (such as an incipient beak) only to lose them before emerging from the egg. Could this retention of ancestral features in an incipient form made it easier for them to re-establish at a later date?

The only living frog with mandibular teeth, Gastrotheca guentheri, copyright Biodiversity Institute, University of Kansas.

There is an evolutionary reversal among hemiphractids that seems more unequivocal, however: one species, Gastrotheca guentheri, is the only known frog in the modern fauna to have teeth in the lower jaw (Wiens 2011). There are a number of other frogs (including some other hemiphractids) in which the lower jaw has tooth-like serrations but G. guentheri is the only species with honest-to-goodness teeth. There seems little doubt that this is a true reversal; for G. guentheri to be the only living frog species to retain the ancestral state would require close to two dozen independent losses with no sign of the feature's retention elsewhere. In this case, while other frogs do not have teeth in the lower jaw, many of them do have teeth in the upper jaw (in some, such as Hemiphractus species, these upper teeth may be modified into prominent fangs for prey capture). So the genes for tooth development are still in place; presumably, G. guentheri has been able to re-develop its lower teeth through the genes for upper teeth being effectively re-deployed to take action elsewhere.

REFERENCES

Frost, D. R., T. Grant. J. N. Faivovich, R. H. Bain, A. Haas, C. F. B. Haddad, R. O. de Sá, A. Channing, M. Wilkinson, S. C. Donnellan, C. J. Raxworthy, J. A. Campbell, B. L. Blott., P. Moler, R. C. Drewes, R. A. Nussbaum, J. D. Lynch, D. M. Green & W. C. Wheeler. 2005. The amphibian tree of life. Bulletin of the American Museum of Natural History 297: 1–370.

Wiens, J. J. 2011. Re-evolution of lost mandibular teeth in frogs after more than 200 million yeatrs, and re-evaluating Dollo's Law. Evolution 65 (5): 1283–1296.

Wiens, J. J., C. A. Kuczynski, W. E. Duellman & T. W. Reeder. 2007. Loss and re-evolution of complex life cycles in marsupial frogs: does ancestral trait reconstruction mislead? Evolution 61 (8): 1886–1899.

New Zealand Fills a Biogeographical Gap

Lateral view of the holotype (and only known specimen) of new species Americovibone remota.

Taylor, C. K. 2016. First record of a representative of Ballarrinae (Opiliones: Neopilionidae), Americovibone remota sp. nov., from New Zealand. Journal of Arachnology 44 (2): 194–198.

New paper, and new species of phalangioid harvestman, out! And one that I'm pretty excited by, even if the vagaries of time allocation mean that I haven't been able to get the post out until a couple of weeks after it happened. After several years of studying New Zealand's long-legged harvestman fauna, I have to confess I was getting a bit complacent about. I certainly knew that I had not seen every species that the country had to offer, but I still thought that there were no real surprises remaining. The overall outline had become clear; any species of long-legged harvestman remaining to be described from New Zealand would be fairly closely akin to those already known.

Oh boy, was I wrong.

At some point last year (or maybe the year before), I was sorting through a jarful of specimens that were still waiting on my attention. In one of the vials, its contents collected in a remote part of the south-west South Island, was a tiny, wispy specimen that I at first glance paid little mind to. Newly-hatched juveniles are not uncommonly collected; they are almost always unidentifiable and end up being just chucked back into the jar never to be looked at again. Nevertheless, I pulled the specimen out to confirm that my first impression was correct. I placed the specimen in a dish under the microscope and glanced through the eyepiece. Then looked again, my eyes doubtless boggling. I may have even sworn a little. Not only was the specimen not a juvenile but fully adult, it was something I had long given up on seeing from New Zealand: a ballarrine.

Dorsal view of the main body.

The Ballarrinae are an unusual group of harvestmen that were not recognised until fairly recently. The group was named by Hunt & Cokendolpher in 1991 with species found in South Africa, Australia and South America. The South African species Vibone vetusta was the only one described prior to Hunt & Cokendolpher's (1991) paper, and until now no further species had been described since. The main reason these animals were overlooked previously is probably their size: ballarrines include some of the smallest of all harvestmen (the specimen I was looking at, for instance, has a central body only a bit over a millimetre long). Ballarrines differ from other harvestmen in the form of their pedipalps which are relatively long and have the patella much longer than the tibia (the converse is usually the case). Whereas other phalangioid harvestmen have the patella and tibia of the pedipalp more or less in a straight line or have the tibia bent slightly downwards, Hunt & Cokendolpher (1991) were struck by how the ballarrines had the tibia reflexed upwards relative to the patella. Ballarrine pedipalps also lack a terminal claw, and have only a relatively few glandular hairs instead of the denser covering of simple hairs found in other harvestmen. As noted in an earlier post and paper that I was associated with (Wolff et al. 2016), the overall pedipalp form is adapted for preying on small animals such as springtails: the long pedipalp acts like a tentacle that can be whipped forward to trap prey with its sticky hairs.

Until this point, New Zealand had been a puzzling gap in the Ballarrinae's otherwise classic Gondwanan distribution (long-term readers may recall that this is the second time I've seen a puzzling biogeographical lacuna filled). I didn't have any idea why that should be absent but even after looking at probably thousands of harvestmen specimens from all corners of the country I still hadn't seen any. Hence my immediate excitement about the find, but said excitement was also leavened with a certain degree of caution. Harvestmen taxonomy is heavily dependent on features of the males (particularly the male genitalia) with females of closely related species often being indistinguishable. Unfortunately, the only specimen of New Zealand ballarrine I had on hand was female. Sorting through the remainder of the collection I was working on failed to turn up any more. I even considered whether I could wrangle a trip to the original collection locality to see if I could find more specimens, but that proved unfeasible. The ballarrine had been collected by J. Dugdale in 1980 at a spot called the Dart Hut, which lies at the summit of the Rees-Dart walking track in Mount Aspiring National Park. This is a pretty isolated part of the country with no permanent population and no nearby roads. Travelling to the Dart Hut by foot takes a minimum of two days each way; the usual time taken to travel the Rees-Dart is five days (its supposed to be a nice hike that travels through similar terrain to the more famous Milford Trail without the massive crowds of the latter). What is more, at the time I was looking into it, the Rees-Dart was closed until further notice due to flooding earlier in the year taking out one of the bridges along it. Nevertheless, I eventually decided that the value of publicising the presence of this significant group in New Zealand outweighed the risk of not yet being able to confirm male morphology. Unfortunately, the nature of the specimen (spindly legs everywhere!) meant that I found myself unable to get good photographs and the resulting paper had to be illustrated with (always somewhat ropey when I do them) hand-drawn illustrations; nevertheless, the best photos I got are here in this post.

The tentacle-y pedipalp of A. remota is considerably longer than the central body; it's nearly as long as one of the legs!

Fortunately, sexual dimorphism within ballarrines tends to be low. I was very interested to see that the New Zealand ballarrine was more similar to the South American species Americovibone lanfrancoae than to any of the Australian species; so much so, in fact, that I ended up assigning it to the same genus as Americovibone remota. Americovibone lanfrancoae is also a very rare species, being described from only two known specimens from the Tierra del Fuego region. The most obvious difference between A. remota and A. lanfrancoae is that, in the former, the tibia of the pedipalp is not reflexed back above the patella as in every other ballarrine but is bent slightly downwards in a more standard position for phalangioids. This has some very interesting implications for ballarrine phylogeny. A molecular phylogenetic study of long-legged harvestmen by Groh & Giribet (2014) that included two ballarrines (the South African Vibone vetusta and the Australian Ballarra longipalpis) failed to unite the two as a clade. If accurate, this result would require the distinctive ballarrine pedipalp to have evolved on more than one occasion. The observation that A. remota may retain a more plesiomorphic pedipalp morphology could provide some correlation for this possibility.

But if Ballarrinae are indeed present in New Zealand, why are they apparently so rare? Part of the reason may be to do with habitat. Both the New Zealand and South American species of Americovibone are known from forests dominated by Nothofagus, southern beech. This tree genus is widespread in upland and colder parts of New Zealand. A bit north of the collection locality for A. remota, however, is an area where the beech forests disappear for a distance of a couple of hundred kilometres: this has been referred to as the "Nothofagus gap". Studies on other groups of organisms show that this gap is a significant one for New Zealand biogeography, with many beech-associated species restricted to one side or the other of the gap. Could A. remota be a specialist of the south-west beech forests of the South Island? If so, it is unique to one of New Zealand's least known corners.

REFERENCES

Hunt, G. S., & J. C. Cokendolpher. 1991. Ballarrinae, a new subfamily of harvestmen from the Southern Hemisphere. Records of the Australian Museum 43: 131–169.

Wolff, J. O., A. L. Schönhofer, J. Martens, H. Wijnhoven, C. K. Taylor & S. N. Gorb. 2016. The evolution of pedipalps and glandular hairs as predatory devices in harvestmen (Arachnida, Opiliones). Zoological Journal of the Linnean Society 177 (3): 558–601.

Many Kinds of Herring

The original herring: Baltic herrings Clupea harengus membras, copyright Riku Lumiaro.

The subject of today's post is something that I'm sure that you've all encountered at one time or another. It's a group of animals that features highly in the world's food supply. Some of you may be grat fans of these animals and seek them out on a regular basis; others may not be so enthused. They go by many names: herring, sardines, sprats, shad... but all are members of the fish family Clupeidae.

For the most part, clupeids are a prime example of what I think of as 'fishy' fish: that is, fish that look exactly how the majority of people imagine a fish to look (as opposed, say, to some of those deep-sea jobs that are all teeth and poor muscle tone). They are most diverse in marine waters of the continental shelf though many spend part or all of their lives in fresh water. Most form schools, sometimes very large ones; it is this tendency to congregate that makes them such an important part of the food chain for humans and other predators. The clupeids themselves are mostly micro-predators, feeding on minute plankton. Most are medium-sized to small fish with large species getting up to a couple of feet in length*. Conversely, species of the south-east Asian freshwater genus Sundasalanx (on which more below) reach maturity at only 15 mm in length.

*Bond (1996) makes the remarkable statement that "Palonia castelnaudi, a freshwater herring of South America, reaches at least 1.5 m (Dr. Barry Chernoff, personal communication)". Not only have I been unable to find another reference to a clupeid of this size, I have been unable to confirm the existence of a species of this name. The same reference gives a maximum length for the Chirocentridae as 3.5 m; a quick search online suggests the correct figure is less than a third of that.

Another commercially significant species: sardines Sardina pilchardus, photographed by Alessandro Duci.

The exact circumscription of the Clupeidae has varied over time. It is the largest family in a clade called the Clupeoidei which is well defined by characters such as a reduction in the lateral line and the presence of the recessus lateralis, a channel running through the pterotic bone between the swim bladder and the inner ear. Other families within the Clupeoidei are the Engraulidae (anchovies), Pristigasteridae (ilishas) and Chirocentridae (wolf herrings). While each of the other families is fairly distinctive, the Clupeidae lack clear uniting features of their own and have tended to be defined as 'the rest'. Historically, some authors have united some or all of the other families within the Clupeidae, or recognised clupeid subgroups as their own additional families.

It therefore would not have come as too much of a surprise when a molecular phylogenetic analysis of the Clupeoidei by Lavoué et al. (2013) did not identify the Clupeidae as a monophyletic group. Instead, both the Pristigasteridae and Chirocentridae were nested within the Clupeidae. What is more, not one of the five subfamilies currently recognised within the clupeids was monophyletic either. Instead, Lavoué et al. found six distinct sublineages within the clupeids; each of these was individually well supported but the broader relationships between them were not. Four of these potentially formed a clade that may correspond to a restricted Clupeidae. However, members of the 'Dussumieriinae' (which differ from other clupeids in the shape of their pelvic scutes) formed two external lineages: one was potentially the sister group to all other clupeoids except the Engraulidae whereas the round herring genus Etrumeus was weakly placed as sister to the Chirocentridae. To the best of my knowledge, no-one has yet suggested a formal reclassification of the clupeoids as a result of such studies, but it seems likely that we will either see the Clupeidae expanded to include the chirocentrids and pristigasterids, or restricted to exclude the dussumieriines. Again, either one of these options would align with alternative classifications used in the past.

The paedomorphic Sundasalanx microps, copyright Michael Lo.

Also of note in recent studies on clupeid phylogeny is the position of the south-east Asian freshwater genus Sundasalanx. When first described in 1981, this genus was not recognised as a clupeid or even as a clupeoid. Instead, it was originally placed in the fish order Osmeriformes, the smelts, together with another fish genus Salanx. Members of these two genera are indeed similar in appearance: they are tiny and transparent, looking overall like whitebait but never growing into a larger adult. However, a study of the morphology of Sundasalanx in 1997 lead to the conclusion that the shared features of Salanx and Sundasalanx were actually convergences resulting from both exhibiting paedomorphy, becoming reproductively mature while still effectively in the larval stage. A relationship of Sundasalanx to the clupeoids was suggested instead and this was later corroborated by molecular analyses (Ishiguro et al. 2005). In fact, Sundasalanx is nested well within the Clupeidae, even in the family's restricted sense. Recent years have seen something of a surge in descriptions of paedomorphic fish (many of which were previously mistaken for juveniles of related taxa). Lavoué et al. (2008) recorded another paedomorphic clupeoid from marine waters of south-east Asia that the identified by molecular analysis as related to the dussumieriines, but to the best of my knowledge this species remains unnamed.

REFERENCES

Bond, C. E. 1996. Biology of Fishes 2^nd ed. Saunders College Publishing.

Ishiguro, N. B., M. Miya, J. G. Inoue & M. Nishida. 2005. Sundasalanx (Sundasalangidae) is a progenetic clupeiform, not a closely-related group of salangids (Osmeriformes): mitogenomic evidence. Journal of Fish Biology 67: 561–569.

Lavoué, S., M. Miya, A. Kawaguchi, T. Yoshino & M. Nishida. 2008. The phylogenetic position of an undescribed paedomorphic clupeiform taxon: mitogenomic evidence. Ichthyol. Res. 55: 328–334.

Lavoué, S., M. Miya, P. Musikasinthorn, W.-J. Chen & M. Nishida. 2013. Mitogenomic evidence for an Indo-west Pacific origin of the Clupeoidei (Teleostei: Clupeiformes). PLoS ONE 8(2): e56485. doi:10.1371/journal.pone.0056485.