Promyopias silvestrii (Santschi)
Bolton, B. & Fisher, B. L., 2008, Afrotropical ants of the ponerine genera Centromyrmex Mayr, Promyopias Santschi gen. rev. and Feroponera gen. n., with a revised key to genera of African Ponerinae (Hymenoptera: Formicidae)., Zootaxa 1929, pp. 1-37: 31-32
treatment provided by
|Promyopias silvestrii (Santschi)|
Myopias (Promyopias) silvestrii Santschi HNS , 1914: 324, fig. 10. Syntype workers, GUINEA: Mamou, 24.viii.1913 (F Silvestri) ( NHMB) [examined]. [Combination in Promyopias HNS by Emery, 1915: 26; in Pseudoponera (Promyopias) HNS by Wheeler, W.M. 1922: 779; in Promyopias HNS by Brown, 1963: 10; in Centromyrmex HNS by Bolton, 1995: 140.] Comb. rev.
Promyopias asili Crawley HNS , 1916: 30, fig. Holotype queen, MALAWI: Mlanje, 15.xi.1913 (S.A. Neave) ( BMNH) [examined]. [Combination in Pseudoponera (Promyopias) HNS by Wheeler, W.M. 1922: 779. Synonymy with silvestrii HNS by Brown, 1963: 10.]
WORKER. TL 6.0-6.3, HL 1.05-1.16, HW 1.00-1.12, CI 95-99, ML 0.62-0.68, MI 55-61, SL 0.62-0.64, SI 57-62, PW 0.74-0.86, WL 1.78-1.90 (5 measured).
With characters of the genus and the following. Dorsum of head densely punctulate-costulate, the sculpture stops near the posterior margin so that the occipital surface is mostly smooth and shining. Ventral surface of head longitudinally striolate and with scattered small punctures. Head capsule deep, in profile the maximum depth about 0.75 x HL. Scapes and cephalic dorsum with dense long pubescence that may be elevated, but without long setae such as are present on the clypeus and inner mandibular margins. Pronotum bluntly and obtusely marginate anteriorly and laterally. Metanotal groove vestigial to distinct across the dorsum, not impressed in profile. Pronotal dorsum broadly and densely punctate except for the median strip, which is smooth. Punctate sculpture on mesonotum weaker and more widely spaced than on pronotum; on propodeal dorsum the punctures weaker still, very sparse and almost effaced posteriorly. Sides of mesosoma finely striolate everywhere, or at most with posterior portion of mesopleuron smooth. PW about 1.85 x the maximum width of the propodeal dorsum. Gastral tergites with scattered small punctures. Dorsal surfaces of body with conspicuous pubescence or very short standing hairs everywhere. Occasionally one or two longer setae may occur on the petiole and gastral tergites 1-3, but long conspicuous setae are mostly confined to the apical gastral segment and the gastral sternites.
QUEEN. TL 7.6, HL 1.14, HW 1.17, CI 103, OI 21, ML 0.72, MI 63, SL 0.68, SI 58, PW 0.97, WL 2.32. All main morphological characters of the worker are duplicated in the queen caste; see under diagnosis of the genus.
An uncommon but widely distributed species. Its diet, presumably termites but not actually demonstrated, may be more restricted or specialised than in Centromyrmex HNS . The morphology of the mandible is unique and immediately identifies silvestrii HNS .
Material examined. Guinea: Mamou (F. Silvestri). Ivory Coast: For. de Teke, Anyama (T. Diomande); Lamto, Toumodi (J. Levieux); Goudi (J. Levieux). Cameroun: Prov. Sud-Ouest, Bimbia Forest, ESE Limbe (B.L. Fisher). Angola: S. Rob't Williams (Ross & Lorenzen). Malawi: Mlanje (S.A. Neave)
The three characters discussed below may diagnose a Centromyrmex HNS genus group within tribe Ponerini (sensu Bolton, 2003), which contains the three genera Centromyrmex HNS , Promyopias HNS and Feroponera HNS . At present none of these characters have been proven to be synapomorphies or independently evolved, but they are universal in these genera. The status of the characters must await a more comprehensive survey of the entire tribe.
1 Presence of strongly sclerotised, stoutly spiniform traction setae on the metabasitarsus in workers and queens.
Only these three genera in Ponerini have stout spiniform traction setae on the metabasitarsus in the female castes. Similar setae, usually more strongly developed, are also universal on the mesotibia and mesobasitarsus of all three genera. Elsewhere in the tribe such setae also occur on the mesotibia, and sometimes also the mesobasitarsus in Cryptopone HNS , though they are never as strongly developed; and on the mesotibia of a single species of the Plectroctena HNS genus group, Psalidomyrmex foveolatus HNS . However, none of these exhibit such setae on the metabasitarsus.
Ps. foveolatus HNS acquired mesotibial spiniform setae independently, as the Plectroctena HNS genus group ( Plectroctena HNS (16 species), Loboponera HNS (9 species) and Psalidomyrmex HNS (6 species)) has a unique set of apomorphies(Bolton & Brown, 2002) not exhibited by the Centromyrmex HNS group. No other member of the Plectroctena HNS group has spiniform traction setae on any of the legs.
In Cryptopone HNS (22 species) the traction setae are more feebly developed, are restricted to the mid-leg (usually just to the mesotibia), and are always absent from the metabasitarsus. In addition, Cryptopone HNS species differ from the genera treated here as all have a basal mandibular pit present and a palp formula of 2,2 at maximum(Brown, 1963). It therefore seems reasonable to assume that spiniform traction setae evolved independently in Cryptopone HNS .
2 Helcium projects from near midheight of anterior face of first gastral segment in workers and queens. In Ponerini the helcium is usually attached very low on the anterior face of the first gastral segment, and the first gastal tergite forms a relatively long vertical face above it. Exceptions to this, in addition to the Centromyrmex HNS group, where the helcium is relatively high and the anterior face of the first gastral tergite is shortened, occur in Harpegnathos HNS , various Cryptopone HNS species and the monotypic genera Dolioponera HNS and Boloponera HNS . Fisher (2006) speculates that the last two together may constitute the sister-group of the Plectroctena HNS group of genera. Harpegnathos HNS , based on its unique morphology, cannot be considered as close to Centromyrmex HNS and its allies. Cryptopone HNS , despite its differences from the potential group under discussion here, may be related but the possibility awaits investigation.
3 Eyes absent in worker caste.
The absence of eyes in the worker caste may be a synapomorphy of the group. In most genera of Ponerini eyes are usually present, even if often very reduced, but there are some where eyes are absent in some species but present in others (e.g. Hypoponera HNS , Plectroctena HNS , Cryptopone HNS , Pachycondyla HNS , Myopias HNS ), and in Dolioponera HNS larger workers have eyes while smaller ones are eyeless (Fisher, 2006). Loss of eyes may therefore be apomorphic within species, in individual species in a genus, or in a group of species within a genus, but it is worth noting that universal loss appears only to have happened in the three genera revised here.
Switzerland, Basel, Naturhistorisches Museum
United Kingdom, London, The Natural History Museum [formerly British Museum (Natural History)]
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