Tuesday 29 May 2018

The Unequal Conehead, Conocephalus (Conocephalus) inequalis Uvarov, 1928

Conocephalus Thunberg, 1815 is a massive, successful genus, with well over one hundred species across all continents except Antarctica, and the Orthoptera Species File (OSF) recording forty species within Africa. Throughout their range, they - like many members of the subfamily Conocephalinae Krauss, 1902 - are primarily associated with grassland areas, where they can be an abundant and conspicuous feature of the invertebrate community. In southern Africa, where such fat-and-protein rich insects are an important food resource for humans, they are not so valued as the larger Pseudorhynchus Serville, 1838 and Ruspolia Schulthess, 1898, but are commonly more abundant than either.

Neither I nor the folks at the OSF have found any records of this genus from Zambia, but they are definitely here; the pan-African Conocephalus (Conocephalus) conocephalus, first described by the taxonomic powerhouse that was Carolus Linnaeus in his Systema Naturae (1767), is common across the country, and then there is this little guy: 

Chongwe Distr., Zambia, April 2018

Within the African Conocephalinae, the tribes Agraeciini Redtenbacher, 1891 and Copiphorini Karny, 1912 are largely comprised of more robust insects. Additionally, the majority of the Copiphorini have an extended - sometimes markedly - forward point of the head, distinctly beyond the bases of the antennae, and the Agraeciini are almost exclusively recorded from Tanzania and Kenya, with a single species in Gabon and Cameroon.

This leaves for our consideration the tribe Conocephalini Burmeister, 1838; excluding three species of Thyridorhoptrum Rehn & Hebard, 1915, which seem to be limited to areas North of the equator, the Conocephalini in Africa essentially comprises the previously mentioned Conocephalus and the subtribe Karniellina Hemp & Heller, 2010. While the Karniellina do certainly enter Zambia, being recorded from Muchinga, Northern and Eastern provinces so far (more on that another day, hopefully), males in this group have somewhat shorter elytra (the hardened forewings) and an enlarged pronotum (the conspicuous upper part of the thorax), which in all except one genus (Karniella Rehn, 1914; rather distinctive little beasties from Rwanda and the D.R.C.) are twice the length of the wings - which is not the case here. 

So we turn to Conocephalus itself, and shrink in horror. Even if we make the (dangerous) assumption that all species in this genus in Africa have been described, within the continent, this genus is a mess. Our first port of call is to head to the magnificent, wonderful and previously mentioned Orthoptera Species File, which - short of visiting every museum in every country the Southern African Development Community (SADC), and all those in every country that ever sent entomologists or entomologically-inclined missionaries, colonists or mine operators to them - is the most reliable way of finding out which species are where. 

Excluding species that are in Africa geographically, but don't penetrate (oo-er) south of the Sahara; and, to make our initial workload easier, ignoring species that the OSF only has records from West Africa for (for now - as distribution data is fairly patchy still, this can be unreliable at times), we're looking at twenty-five described species to compare. We can immediately exclude the seven bizarre, elongate species of subgenus Megalotheca, which, although they probably are present in Zambia, look more like a piece of grass dreaming of being a katydid than anything else. Knowing we may have to revisit them later, we're going to put the six species for which the OSF's illustrations show long-winged type specimens to one side - tentatively, though, because to add to the chaos, some species of Conocephalus are known to vary seasonally between long-winged and short-winged forms. This still leaves us with twelve species: seven not illustrated at all, and five with short-winged type specimens illustrated. 

One of the five illustated species is Conocephalus (Conocephalus) inaequalis, and the photographs of the type show that, despite being 90 years old, the type still shows much of the colouring of our little chap. This isn't all that meaningful in itself, but when Uvarov described this species in 1928, he also wrote about five of the other species we want to examine or eliminate, so this seems like a promising rabbit-hole to wriggle down into. 

Before we go any further, anyone of a particularly sensitive disposition should probably look away. This is because, in order to describe why I'm moderately confident that we landed through (mostly) luck on the right insect, I have to show you a picture of the business end of a male katydid, and I don't mean the end it eats with.




On the left, you can see the somewhat obscured terminalia of the individual shown near the beginning of all this preamble; he was not overly co-operative, and with it being cold and dark when we met, I didn't check on the quality of my pictures until after I'd gone back inside.  You can, however, just about make out two spines coming off the inside of his cerci (the arm-like structures at each side), although due to the angle and his poorly-placed hindleg, this takes some peering.





Fortunately, back in 2013, I managed to get a picture of a somewhat more co-operative male which shows this a little more clearly; notice the long, black-tipped spine pointing inwards from just behind the blunt tip of the cercus (no, not the type with dancing bears and trapeze artists), and a second one just a little further back from the tip, about half as long.





Well, as it turns out, Uvarov devoted some time to providing illustrations and descriptions of this end of those five little katydids, and both Conocephalus (Anisoptera) rhodesianus (Peringuey, 1916) and C. (A.) bechuanensis (Peringuey, 1916) are quite, quite different: rhodesianus, described from Zimbabwe (then Southern Rhodesia) has single-spined cerci, which bechuanensis has a tiny second spine that doesn't protrude inward, but rather nestles on top of the large terminal spine.

This is progress; all ten of our remaining suspects are within the subgenus Conocephalus. Exciting times (I speak from a highly caffeinated position, so I recognise that others may be less excited by this).

But wait, there's more. Conocephalus peringueyi, which outside of this paper has only ever been mentioned by the OSF itself, is entirely different, without any long, inwardly projecting spines; and on the subject of C.  inaequalis, Uvarov describes it as:

"similar to C. caudalis, differing from it in the structure of the male genitalia, and in the development of the elytra. The latter are longer than the pronotum, reaching to the middle of the abdomen, with the apex parabolic; they are greenish in front of the radial veins with are green, and brownish behind them, with brown spots along the middle... Cercus similar to that in C. caudalis, but its inner teeth are very unequal in size, the one nearer the base being much shorter and obtuse"


Elytra longer than the pronotum - check; they don't reach the mid-point on the abdomen, but the abdomen of your average grasshopper is of quite variable size depending how well fed, out of breath or dead they are, and the pronotum-to-elytrum proportion is consistent with Uvarov's measurements (elytra 1.5 times length of pronotum) - so check; tips of elytra a smooth, u-shaped curve - check; colour characters - check, except that I can't see any clearly marked brown spots; but brown spots on brownish don't sound too visible at the best of times; and cerci - very much check.

Generally a pretty convincing description; the species Uvarov has grouped C. inequalis with, he's also ruled out for us; if we head to Walker's description of Conocephalus  caudalis (Walker, 1869), we can also incidentally take C. tenellus and C. punctipennis out of the running, since both of them have hind wings longer than the fore wings, and if our little conehead has hindwings at all, they're not even long enough to see; his description of C. caudalis turns out to be a dud; he describes only the female, does so briefly, and apparently doesn't bother to illustrate her; the male was only described some time later by Redtenbacher (1891); his illustration (under synonym Xiphidium natalense) confirms what Uvarov implied: the teeth of the male's cerci are equal in size in C. caudalis; from his descriptions, C. africanus (from Gabon) is another long-winged species, so that's ruled out, while his description of C. guineensis (also from Gabon) covers only the female, which is short-winged, doesn't really give us any reason beyond geography to suspect that we're not looking at that species. Not losing hope, we turn to the last two species: Conocephalus brincki and Conocephalus basutoanus, both described Chopard in 1955.

You know how people who'd read all the books George R.R. Martin had written in the series before Game of Thrones aired used to prematurely distrust certain characters who, it turned out, were absolute monsters? I react that way to Chopard. He seems to have spent his life going out of his way to publish papers in journals I do not have access to (even when UNZA Library isn't closed for Cholera); while the type for C. basutoanus (from Lesotho) is illustrated on OSF, and shows that the male has quite different cerci, the type for C. brincki is not illustrated, and so I cannot comment on it. Geographically, it shouldn't be a problem - the single record is from high mountain heath in the cape - but leaving it here, as "probably inequalis, but could be guineensis or brincki at a stretch" feels like an anticlimax. If only there was some authority that had written about the unusual features of inequalis after all these species had been described...

Oh, wait.

Heller et al did exactly that in 2014, regarding a strange little conehead from the Eastern Congo, describing the male as being similar in the structure of the cerci to inequalis, noting that "this type of cercus does not belong to the common ones in the genus (not figured e.g. in the only available multi-species study of the genus by Pitkin (1980) on species of the Pacific area)".

Is it disingenuous that I knew this before I took you on this long and twisted journey? I actually read it after Uvarov's description, but as Heller et al note the absence of stable identification characters for the rest of the African Conocephalus (which I am tempted to interpret as nobody knows where Chopard's descriptions are), I then went through the rest of these species in an effort to reach a slightly greater degree of certainty.

Did I get it? Somewhat. The species was described from an unknown location in South Africa, probably in the Transvaal, and seemingly also eastern D.R.C., and people with more access to resources and far better qualified than I could go no further than I have to identify a seemingly identical specimen; if inequalis-like animals were present in northern S.A. and eastern D.R.C. but nowhere in between, it would seem impossible for this to be a single species; it may be a little naive, but despite sharing Heller et al's concerns, I find myself feeling that stumbling on this little conehead in Zambia adds just a little bit of confidence to their identification.

And it could have been worse: trying to identify male coneheads in Africa may be nigh-on impossible, but the females are even harder; this female, by association with the male above, I'm assuming to also be Conocephalus (Conocephalus) inequalis.












References:

Characteristics of the Karniellina in: Hemp, C., Heller, K.-G., Kehl, S., Warchalowska-Sliwa, E., Wägele, J.W. & Hemp., A (2010). The Phlesirtes complex (Orthoptera, Tettigoniidae, Conocephalinae, Conocephalini) reviewed: integrating morphological, molecular chromosomal and bioacoustic data. Systematic Entomology 35, pp. 554-580

Descriptions of Conocephalus inequalis, C. peringueyi, C. bechuanensis and C. rhodesiensis in: Uvarov, B.P. (1928). Notes on the Types of Orthoptera described by Dr. L. Péringuey. Annals of the South African Museum 25 pp. 341-357

Descriptions of Conocephalus tenellus, Conocephalus caudalis and Conocephalus punctipennis in: Walker, F. (1869). Catalogue of the Specimens of Dermaptera Saltatoria in the Collection of the British Museum part II, pp. 225-423

Descriptions of Conocephalus africanus, Conocephalus guineensis and male of caudalis in: Redtenbacher, J. (1891) Monographie der Conocephaliden. Verhandlungen der Kaiserlich-Königlichen Zoologisch-Botanischen Gesellschaft in Wien 41 pp. 315-562

and finally:

Support for throwing my hands up in the air and saying b***er it, it's inaequalis in: Heller, K.G., Hemp, C., Liu, C. & Volleth, M. (2014). Taxonomic, bioacoustic and faunistic data on a collection of Tettigonioidea from Eastern Congo (Insecta: Orthoptera). Zootaxa 3785 (3), pp. 343-376.







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