Field of Science

Rhampsinitus Re-Redux

I've featured the African harvestman genus Rhampsinitus on this site twice before, but I'm going to have another dive into it today. There's still more I can say about this remarkable genus.

Male Rhampsinitus, possibly R. leighi, copyright Peter Vos. The individual ahead of the male is another Rhampsinitus, probably a female; there's also a short-legged harvestmen beneath the male.


There's more I could say about African phalangiids in general, in fact. There's never been a proper phylogenetic study of the long-legged harvestman family Phalangiidae, so we can't speak with confidence about the relationships between the African members of this group and their relatives elsewhere, but it would not be unexpected if the sub-Saharan phalangiids form an evolutionarily coherent group. Many of the family's most striking exemplars are to be found on the African continent: Cristina with their thick, spiky front legs; sleek, flattened Odontobunus, Guruia with their chelicerae like a pair of jar tongs held in a boxing glove. Rhampsinitus' current position as the best-known African harvestman genus is probably due not only to its diversity but also to its more temperate centre of distribution placing it closer to researchers than these other more equatorial genera.

As mentioned in my first post on the genus, there are currently over forty recognised species of Rhampsinitus. As alluded to in my second post, that number might be expected to change in the future. No reliable identification key is currently available for Rhampsinitus, nor is the information available for many species that would allow such a key to be written. A key to the southern African species was provided by Kauri (1961) but, while I did find this key invaluable when I conducted my own tentative foray into rhampsinitology, I couldn't recommend it to a novice. Kauri was simply unaware of the extreme variation that can be found among male Rhampsinitus belonging to a single species. There are only a handful of species for which both major and minor males have been described and, as I explained previously, minor males may not be identifiable to species without examining genitalia.

Probably a male Rhampsinitus vittatus, copyright Nanna.


This, obviously, is a problem for the handful of species that have been described from what appear to be minor males. Some of these, such as Rhampsinitus fissidens and R. hewittius, are probably doomed to remain mysteries at least until someone redescribes their types. Others may be more recognisable. Rhampsinitus qachasneki is an unusually spiny species described from the mountains of Lesotho, with some of the denticles along the front edge of the body multi-pointed. These distinctive denticles, like repurposed muntjak antlers, might reasonably be expected to be present in any major males of this species, if they exist. The challenge may be even greater for the handle of species that have been described from females. Nevertheless, the known female of R. maculatus, another Lesotho mountain species, has a distinctive spotted colour pattern and thick, remarkably hairy pedipalps that might be expected to show their analogues in the unknown males (again, if they exist: we're kind of glossing over the point that some harvestmen species are known to be parthenogenetic, because harvestmen systematics is so heavily predicated on male genital morphology that the idea of an all-female harvestman species is a trifle intimidating*).

*I assume that this is precisely what Zappa had in mind when he got to the end of Thing-Fish.

Then, of course, there's the persistent question of Rhampsinitus lalandei. This was the first species included in Rhampsinitus in 1879 and as such represents the type or sine qua non of the genus. As was not unusual for the time, its author Eugene Simon was a bit vague about where his original specimen(s) had come from, giving the locality as simply 'Cafrerie'. Cafrerie, rendered in English as Kaffraria or Kaffirland, is a geographical designation that has fallen out of favour these days for reasons I would hope to be obvious, but was commonly used during the 1800s to refer to the area around the eastern coast of modern South Africa, particularly around Port Elizabeth. Unfortunately, Simon's description of R. lalandei is not definitive by modern standards—most of the features described could apply to any number of Rhampsinitus species—and Simon's original specimen appears to have been lost. This presents a problem for any who would suggest that this large genus should be divided up as it might become uncertain which division represents the true Rhampsinitus. Starega (2009) suggested that R. lalandei might be the same as R. crassus, a species definitely found in the Port Elizabeth region. However, it should be noted that Simon described R. lalandei as being irregularly armed with denticles dorsally. In the majority of Rhampsinitus species, the denticles on the opisthosoma form very neat transverse rows, but in others they are a bit more messily placed. Rhampsinitus crassus is one of the former species but the description of R. lalandei suggests it may have been one of the latter. So if anyone's looking at harvestmen from around that area, keep your eyes open.

REFERENCES

Kauri, H. 1961. Opiliones. In: Hanström, B., P. Brinck & G. Rudebeck (eds) South African Animal Life: Results of the Lund University Expedition in 1950–1951 vol. 8 pp. 9–197. Almqvist & Wiksells Boktryckeri Ab: Uppsala.

Staręga, W. 2009. Some southern African species of the genus Rhampsinitus Simon (Opiliones: Phalangiidae). Zootaxa 1981: 43-56.

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