Empire of the Sunfish

Do you remember when this particular nightmare was vomited forth from the jaws of pop culture hell?


Yes, this was the execrable Billy the Bass, just one more reason we can all be glad that the 90s aren't around any more. But what was it supposed to be?

Smallmouth bass Micropterus dolomieu, photographed by Eric Engbretson.

The bass and sunfishes of the family Centrarchidae are a group of more than thirty species of freshwater fish mostly native to North America east of the Rocky Mountains. A single species, the Sacramento perch Archoplites interruptus, is native to northern California. The family was more widely distributed in the past: the Oligocene–Miocene genera Plioparchus and Boreocentrarchus hail from Alaska, Oregon and the Dakotas (Near & Koppelman 2009). They will also be much more widely distributed in the future: species of the genera Lepomis and Micropterus have been introduced to numerous places around the world as sportfish. The centrarchids are all carnivorous, though the nature of their prey varies from zooplankton to insects to other fish.

White crappie Pomoxis annularis, photographed by D. Ross Robertson.

The molecular analysis of the Centrarchidae by Near et al. (2005) identified the mud sunfish Acantharchus pomotis as sister to all other centrarchids, contrary to its previous inclusion in the subfamily Centrarchinae with other centrarchids possessing more than three spines in the anal fin (Near & Koppelman 2009). Instead, the two genera whose species possess only three anal spines, Lepomis and Micropterus, form a clade that is sister to the remaining 'centrarchine' genera. These are the aforementioned Archoplites, the flier Centrarchus macropterus, the banded sunfishes Enneacanthus, the rock basses Ambloplites and the somewhat unfortunately named crappies of the genus Pomoxis. These are mostly deep-bodied feeders on small invertebrates, though the larger species may also take small fish. Archoplites is a more dedicated piscivore. This latter species is also notable for having less elaborate mating behaviour than other centrarchids: in contrast to the elaborate courtship rituals and nests of other centrarchids, Archoplites males do little more than use the tail fin to dig a small depression (Berra 2007). One can't resist wondering if Archoplites' lax behaviour is connected with its geographic isolation from other species.

Pumpkinseed Lepomis gibbosus, photographed by Cliff.

The genera Micropterus and Lepomis are each more diverse than the centrarchine genera. The black basses of the genus Micropterus are relatively long-bodied compared to other centrarchids, and are all piscivores. Lepomis, with twelve species, is the most diverse centrarchid genus both numerically and ecologically; as well as numerous insectivorous species, it contains the piscivorous warmouth Lepomis gulosus, the specialised planktivorous bluegill L. macrochirus, and two molluscivorous species, the redear sunfish L. microlophus and the pumpkinseed L.gibbosus. Phylogenetic relationships within Lepomis indicate a certain dynamism of ecology as well: a number of species pairs can be identified connecting large and small species, while the two molluscivores are not immediate relatives within the genus (Near et al. 2005).

REFERENCES

Berra, T. M. 2007. Freshwater Fish Distribution. University of Chicago Press.

Near, T. J., D. I. Bolnick & P. C. Wainwright. 2005. Fossil calibrations and molecular divergence time estimates in centrarchid fishes (Teleostei: Centrarchidae). Evolution 59 (8): 1768-1782.

Near, T. J., & J. B. Koppelman. 2009. Species diversity, phylogeny and phylogeography of the Centrarchidae. In: Cooke, S. J., & D. P. Philipp (eds) Centrarchid Fishes: Diversity, biology and conservation, pp. 1-38. Blackwell Publishing.

Chitonous Confusion

Lepidochitona cinerea, photographed by Rokus Groeneveld.

Chitons have been featured at this site once before, in a brief post on the family Ischnochitonidae. Today's post is focused on another chiton family, the Lepidochitonidae.

As noted in the earlier post, the field of chiton classification is a confusing place. The lepidochitonids were characterised by Kass & Van Belle (1985; under the name Lepidochitoninae, as a subfamily of the Ischnochitonidae) as chitons with slit-bearing valves, no extra-pigmentary eyes (i.e. no cuticular eyes outside the aesthetes, which are sensory canals in the valves), and a girdle that appears nude or has non-overlapping scales. Contrary to Kass & Van Belle's classification, however, the lepidochitonids do not appear to be immediately related to the ischnochitonids. Lepidochitonids have what are called abanal gills, in which new pairs of gills are only added during development in front of the first pair to develop (so the largest pair of gills is the furthest back), but ischnochitonids have adanal gills, in which new gill pairs are added both in front of and behind the original pair. The significance of this distinction has been corroborated by molecular analysis (Okusu et al. 2003). As for the composition of the Lepidochitonidae itself, Eernisse et al. (2007) referred two genera found in California, Cyanoplax and Nuttallina, to this family, but referred a third erstwhile lepidochitonine Tonicella to the family Mopaliidae, indicating the non-monophyly of the previously recognised grouping. In support of this, they cited in-progress molecular analyses. However, the detailed results of these analyses have yet to appear in print, so we are still unsure what the final face of the Lepidochitonidae will be.

Gould's baby chiton Cyanoplax dentiens, photographed by Gary McDonald.

The species of Cyanoplax are also of interest because of their varying reproductive habits. Four species in this genus studied by Eernisse (1998) are free spawners, releasing eggs into the water column where they hatch into free-swimming larvae that later settle and metamorphose elsewhere. Three other species, in contrast, are brooders, retaining their eggs to hatch at a later stage in development, bypassing the planktonic stage and reaching maturity close to their parent. Two of these brooding species, C. caverna and C. fernaldi, are also the only known examples of simultaneous hermaphrodites among chitons, seemingly able to fertilise their own eggs. As well as in larval development, brooding and free-spawning Cryptoplax species also differ in characters of the eggs, with the eggs of free-spawning species being more ornate than those of brooding species. This is of note as egg ornamentation has been suggested as a phylogenetically significant character in chitons; though this view has also been corroborated by molecular analysis (Okusu et al. 2003), the example of Cyanoplax recommends caution. The contrast between spawning vs brooding species in Cyanoplax also resembles situations found in other marine genera: starfish and annelid worms, for instance, each include examples of closely related yet developmentally distinct taxa.

REFERENCES

Eernisse, D. J. 1988. Reproductive patterns in six species of Lepidochitona (Mollusca: Polyplacophora) from the Pacific coast of North America. Biological Bulletin 174 (3): 287-302.

Eernisse, D. J., R. N. Clark & A. Draeger. 2007. Polyplacophora. In: J. T. Carlton (ed.) Light and Smith Manual: The Intertidal Invertebrates of Central California to Oregon, 4th ed., pp. 701-713. University of California Press: Berkeley.

Kaas, P., & R. A. Van Belle. 1985. Monograph of Living Chitons (Mollusca: Polyplacophora) vol. 2. Suborder Ischnochitonina. Ischnochitonidae: Schizoplacinae, Callochitoninae & Lepidochitoninae. E. J. Brill/Dr W. Backhuys.

Okusu, A., E. Schwabe, D. J. Eernisse & G. Giribet. 2003. Towards a phylogeny of chitons (Mollusca, Polyplacophora) based on combined analysis of five molecular loci. Organisms Diversity & Evolution 3: 281-302.

The Burlinius Head-hiders

Cryptocephalus (Burlinius) bilineatus, photographed by Josef Dvořák.

I may have to confess that, in direct opposition to the Deity, I am not overly fond of beetles. There are, quite simply, far too many of them, and even beetle families can be inordinately difficult to distinguish unless one is an expert (particularly the endless array of minute brown ones). Nevertheless, everything in beetles comes with an exception, and there are some groups that stand out: one of these is the leaf beetles of the Chrysomelidae. Chrysomelids are a highly diverse group, comparable to (though perhaps getting less press than) their close relatives the weevils and longicorns. They come in an enormous array of shapes and colours, and yet almost all (emphasis on almost) seem to carry an unmistakeable stamp saying, "I am a chrysomelid".

Cryptocephalus (Burlinius) pusillus, photographed by Amy.

The chrysomelid subgenus Burlinius of the genus Cryptocephalus includes over 120 species found across the Palaearctic region, with a single species known from the Simien Mountains of Ethiopia (Schöller 2002). The name Cryptocephalus means 'hidden head', and refers to how, when the beetle is viewed from above, the head is usually hidden underneath the pronotum. Species of Burlinius are relatively small with regular lines of punctures on the elytra, but are primarily distinguished from other Cryptocephalus species by the morphology of the male genitalia. The aedeagus (the intromittent organ) bears a dorsodistal appendage covering the dorsal opening, and two symmetrical ventral processes (Erber & Schöller 2006). The external appearance of many Burlinius species is known to be quite variable, and genital morphology is also the best way of distinguishing many species (Warchałowski 1999).

Figures from Warchałowski (1999) showing variation in elytral patterning between individuals of Cryptocephalus jocularius.

As you might have guessed from the vernacular name 'leaf beetles', chrysomelids are generally herbivorous. Host plant records for Burlinius species indicate that they are often polyphagous, feeding on a wide variety of hosts. Burlinius species have been recorded from legumes, composite-flowered plants, spurges, even pines (Erber & Schöller 2006). Cryptocephalus and related taxa belong to a subgroup of the chrysomelids called the Camptostomata, in which the females have an array of chitinous pads called the kotpresse in the rectum (Schöller 2008). The kotpresse is used to encase the eggs when they are laid in a covering made from faeces and other secretions; when the larvae hatches, it uses this covering for protection and adds to it itself as it grows.

Hazel pot beetle Cryptocephalus coryli larva in its protective case, photographed by Roger Key.

REFERENCES

Erber, D., & M. Schöller. 2006. Revision of the Cryptocephalus-species of the Canary Islands and Madeira (Insecta, Coleoptera, Chrysomelidae, Cryptocephalinae). Senckenbergiana Biologica 86 (1): 85-107.

Schöller, M. 2002. The first representative of Cryptocephalus subgen. Burlinius Lopatin from tropical Africa (Chrysomelidae: Cryptocephalinae). Genus 13 (1): 33-37.

Schöller, M. 2008. Comparative morphology of sclerites used by camptosomatan leaf beetles for formation of the extrachorion (Chrysomelidae: Cryptocephalinae, Lamprosomatinae). In: Jolivet, P., J. Santiago-Blay & M. Schmitt. Research on Chrysomelidae vol. 1, pp. 87-120. Brill: Leiden.

Warchałowski, A. 1999. Übersicht der westpaläarktischen Arten der Untergattung Burlinius Lopatin, 1965 (Coleoptera: Chrysomelidae: Cryptocephalus). Genus 10 (4): 529-627.

More on the New Zealand Opiliones

Male of Pantopsalis listeri, photographed by Simon Pollard, used with permission in Taylor (2013).

New paper published today! Hurrah! Except I've already had it pointed out to me that the species descriptions are missing the type depository, and one of the new species names has been mis-spelt in a couple of places. So I must shamefacedly prepare myself a correction...

The paper in question is titled 'Further notes on New Zealand Enantiobuninae (Opiliones, Neopilionidae), with the description of a new genus and two new species'. It's been published in ZooKeys, so it's freely available online at the link just given. As well as the two new species of harvestmen mentioned in the title, the paper also does something that I personally am even more pleased with: it manages to make two nomina dubia not dubia any more!

It started with my own private little eureka moment. A few months back, I was looking through some of the New Zealand harvestmen material that's been waiting for me to examine it. I pulled out one of the specimens and looked at it under the microscope. And as soon as I looked at it, I somehow had a thought pop into my mind: "That's Pantopsalis cheliferoides". Pantopsalis cheliferoides, I hasten to explain, is a species that was first described in 1882 by William Colenso, a missionary based in Ahuriri in Hawke's Bay. Colenso was a fascinating character, living with one hand firmly on the Bible and the other up a native girl's skirt (he was dismissed from the church in 1852 after fathering a child by his wife's maid, and not readmitted to its services until 1894). He produced the first book to be printed in New Zealand, and was the first to translate the Bible into Maori. He was also a keen natural historian, particularly interested in botany. His endeavours in zoology were perhaps a little less sure: when he collected the first specimens of P. cheliferoides, he doesn't seem to have been entirely sure if he was looking at a harvestman, a whip-spider, or a pseudoscorpion, so he kind of hedged his bets in giving it the name of Phalangium (Phrynus) cheliferoides. Unfortunately, P. cheliferoides then became something of a footnote in New Zealand arachnology. I had looked at the type specimen previously, but it wasn't enough for me to be sure of it's identity (and at the time, I was still a student and not confident enough to perform a genitalia dissection on a holotype). But it was enough that, when I came across more specimens of the species, I was able to recognise them for what they were. Hopefully, this will lift the animal that Colenso spent so much time trying to identify* out from its obscurity.

*In Colenso's own words: "I have only seen four specimens in the woods, throughout three years, although from my first seeing one in 1879 (which I failed to capture), I have sought most diligently for specimens. In the following year I accidentally, and most unexpectedly, saw another in the same forest, and though I tried long and arduously to secure it without smashing, I failed to do so; it spread out its long flexible legs so prodigiously, that in the end it escaped among the thick vegetation" (Colenso 1882).

Male Pantopsalis cheliferoides, from Taylor (2013).

The other nomen ex-dubium dealt with in the paper is arguably even more important, as it is the type species of the genus Pantopsalis. This species was first described as Phalangium listeri by A. White back in 1849, in about three lines of text that are completely inadequate to recognise the species in question (with no further locality data given than 'New Zealand'), and the type specimen(s) seem to have since been lost. The species was redescribed by the French arch-arachnologist Eugene Simon in 1879, who placed it in the new genus Pantopsalis. Recently, I was able to borrow Simon's P. listeri specimens from the Muséum national d’Histoire naturelle in Paris; as it turns out, they belong to the same species that I had dealt with in 2004 under the name of Pantopsalis luna. Because the original type was lost, I've designated one of the Paris specimens as the neotype for P. listeri. It isn't entirely certain that Simon was actually looking at the same species as White had been (indeed, as mentioned in the paper, there's some cause to believe he wasn't). But everyone since Simon has followed his lead on the identity of Pantopsalis, and naming one of his specimens as neotype has the advantage of confirming the status quo.

Male of Mangatangi parvum, from Taylor (2013).

The two new species in the paper are Forsteropsalis pureora (as it should have been throughout, dammit) and Mangatangi parvum. The latter species is particularly neat: it's very small compared to some of the other long-legged harvestmen in New Zealand, and certain features suggest that it may represent the sister taxon to the clade containing the genera Pantopsalis and Forsteropsalis. I'm still doing some work to try and test that.

REFERENCES

Colenso, W. 1882. On some newly-discovered New Zealand arachnids. Transactions and Proceedings of the New Zealand Institute 15: 165–73.

Trichadenotecnum: Six Spots and Spiny Terminalia

Trichadenotecnum sexpunctatum, photographed by Brian Valentine.

The animal in the photo above is a typical representative of Trichadenotecnum, a diverse genus of the barklice. About 200 species have been assigned to this genus from almost all the major biogeographic regions of the world except Australia (Yoshizawa et al. 2007); of the two species recorded from Australia and assigned to this genus, one (Ptycta enderleini) has recently been excluded from Trichadenotecnum, and the other (Trichadenotecnum circularoides) is probably a recent introduction from the Americas (Yoshizawa & Smithers 2006). Though long regarded as suspectly heterogenous, the genus has been extensively reviewed in recent years, particularly by Kazunori Yoshizawa of Hokkaido University and associates (Yoshizawa 2001, 2004; Yoshizawa et al. 2008). Members of Trichadenotecnum are characterised by a distinctive array of wing markings, visible in the above photo. Note, in particular, the series of six submarginal spots forming a U-shape towards the end of each wing (though, confusingly, these characteristic markings can become difficult to distinguish in species in which the wings are more heavily spotted overall). The genus is also distinguished by certain features of the male terminalia (or, in layman's terms, the bum) with a number of processes developed on the hypandrium, the posteriormost segment of the underside of the abdomen that covers the phallosome, the intromittent organ in Psocoptera. These processes vary in development between species, and often themselves bear arrays of small spines or teeth. A number of species of Trichadenotecnum also have the terminalia assymmetrically developed, with the left and right lobes of the hypandrium (for instance) differently sized and/or shaped, though the functional significance of this arrangement (if any) remains unknown.

Various views of the terminalia of Trichadenotecnum alexanderae, from Yoshizawa (2001). In life, the phallosome is contained within the underside of the terminalia.

The variability of the terminalia between species of Trichadenotecnum makes them a rich source of characters for use in taxonomy. The problem with this, of course, is that you need adult males, and that isn't always easy. Particularly in a group like Psocoptera, which seem to show a particular tendency for parthenogenesis. A number of Trichadenotecnum species are not, as yet, known to produce males, including the aforementioned T. circularoides, necessitating identifiers to fall back largely on wing markings. Trichadenotecnum circularoides has been recorded from Angola, east Asia, Australia, North America and Brazil; the distribution of closely related species suggests that the last locality represents its original homeland with human dispersal carrying it elsewhere (Yoshizawa et al. 2008). The New World species of Trichadenotecnum appear to fall within a small number of clades: one including T. circularoides is the sister group to other members of the genus, while the T. alexanderae species group is Holarctic in distribution. The majority of New World species, however, form a single lineage referred to as the 'bulky clade' by Yoshizawa et al. (2008). Members of the bulky clade have a movable median tongue on the hypandrium that bears a dorsal covering of denticles or spines. Yoshizawa et al. (2008) suggested that, as the bulky clade was nested amongst a number of Old World lineages, this group may represent a relatively recent invasion of the Americas, probably by way of the Bering Strait.

Nymphs of Trichadenotecnum possess glandular hairs to which frass and pieces of lichen become attached, providing them with camouflage. This individual was photographed by Charley Eiseman.
REFERENCES

Yoshizawa, K. 2001. A systematic revision of Japanese Trichadenotecnum Enderlein (Psocodea: ‘Psocoptera’: Psocidae: Ptyctini), with redefinition and subdivision of the genus. Invertebrate Taxonomy 15: 159-204.

Yoshizawa, K. 2004. Molecular phylogeny of major lineages of Trichadenotecnum and a review of diagnostic morphological characters (Psocoptera: Psocidae). Systematic Entomology 29: 383-394.

Yoshizawa, K., A. N. García Aldrete & E. L. Mockford. 2008. Systematics and biogeography of the New World species of Trichadenotecnum Enderlein (Insecta: Psocodea: ‘Psocoptera’: Psocidae). Zoological Journal of the Linnean Society 153: 651-723.

Yoshizawa, K., C. Lienhard & V. K. Thapa. 2007. Systematic study of the genus Trichadenotecnum in Nepal. Insecta Matsumurana, new series 63: 1-33.

Yoshizawa, K., & C. N. Smithers. 2006. Systematic position of Trichadenotecnum enderleini (Roesler) (Psocodea: “Psocoptera”: Psocidae). Records of the Australian Museum 58: 411-415.