Polyrhachis revoili

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Polyrhachis revoili
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Camponotini
Genus: Polyrhachis
Subgenus: Myrma
Species group: revoili
Species: P. revoili
Binomial name
Polyrhachis revoili
André, 1887

Polyrhachis revoili casent0227558 p 1 high.jpg

Polyrhachis revoili casent0227558 d 1 high.jpg

Specimen Labels

Nothing is known about the biology of Polyrhachis revoili.

Identification

A member of the Polyrhachis revoili species-group.

Rigato (2016) - The main differences between revoili and Polyrhachis weissi are as follows:

Polyrhachis revoili holotype (gyne) Polyrhachis weissi
Anterior clypeal margin with a shallow and wide lobe, with distinct right-angled corners. Anterior clypeal margin entire, not lobed.
Scape abundantly hairy, many hairs are as long as twice the maximum scape width. Scape with standing hairs (when present) at most as long as scape width.
Head in full face view elongate oval; its posterior margin uniformly and strongly convex. Head in full face view distinctly trapezoidal; its posterior margin wide and weakly convex and with distinct posterior corners.
Dorsal cephalic sculpture irregular and mostly reticulate. Dorsal cephalic sculpture regular, longitudinally finely rugulose.

P. revoili can be compared to other species of the group bearing a clypeal lobe as well, e.g. Polyrhachis volkarti and Polyrhachis kohli; yet, I could not find any worker looking conspecific with the revoili type.

Bolton (1973) - The present study implies that revoili and Polyrhachis weissi must be treated as separate although very closely related species. The characters used to separate them appear quite trivial, but are apparently consistent. Further study may show this premise to be incorrect but for the present the species emerge as indicated below.

P. revoili is a larger, noticeably more thickset species (PW 1.40 or more) with a distribution limited to the southern savannah and veldt regions. Erect hairs are more numerous everywhere ( > 30 on each antennal scape) and the pubescence is dense enough to hide the sculpturation of the alitrunk, at least in part. Of the constituent segments of the dorsal alitrunk only the pronotum is distinctly longitudinally rugose, whilst on the other surfaces the rugae are disorganised or a rugoreticulum is present. On the other hand, weissi is a smaller, more slender species (PW 1.26 or less) restricted to the forested areas of West and Central Africa. Erect hairs are more sparse (from none to about 10 on each scape) and the pubescence is fine and short, not masking the sculpturation. The entire dorsum of the alitrunk is sharply longitudinally rugose.

Keys including this Species

Distribution

Distribution based on Regional Taxon Lists

Afrotropical Region: Somalia (type locality).

Distribution based on AntMaps

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Distribution based on AntWeb specimens

Check data from AntWeb

Biology

Fungi

This species is a host for the fungus Ophiocordyceps unilaterialis (Shrestha et al., 2017).

Castes

Worker

Queen

Nomenclature

The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.

  • revoili. Polyrhachis revoili André, 1887: 285 (q.) SOMALIA. Forel, 1894b: 71 (w.); Forel, 1916: 452 (m.). Combination in P. (Pseudocyrtomyrma): Emery, 1921e: 23; Emery, 1925b: 207; in P. (Myrma): Forel, 1916: 452; Wheeler, W.M. 1922a 999; Bolton, 1973b: 338.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Bolton (1973) - TL 6.1-6.5, HL 1.51-1.59, HW 1.44-1.48, CI 93-95, SL 1.63-1.66, SI 112-113, PW 1.40-1.48, MTL 1.66-1.70. (7 measured.)

Anterior clypeal margin arcuate and entire or with a very shallow, small median emargination. Eyes convex, the sides of the head in front of the eyes weakly convex and converging anteriorly. Behind the eyes the sides round into the very shallowly convex occipital margin. Alitrunk not marginate, transversely convex dorsally. The sutures reduced to faint lines; promesonotal suture rather better defined than the metanotal groove, which is not impressed. Pronotum very broad, more than twice the width of the propodeum measured across the teeth. Pronotum with a pair of short, acute spines of variable length, the propodeum with a pair of upcurved teeth. Petiole armed with a long pair of spines dorsally and a shorter, upcurved lateral pair. Anterior face of first gastral segment shallowly concave medially.

Head, body and appendages everywhere with abundant, erect, white to greyish hairs. Pubescence greyish and dense, partially or wholly concealing the sculpturation upon the dorsum of the alitrunk.

Head finely, longitudinally striate-rugose. Dorsum of the pronotum similar to head but rugae less distinct and with a tendency to meander. On the dorsa of the mesonotum and propodeum the rugae are disorganised or arranged into a fine, loose rugoreticulum. Gaster finely reticulate-punctate or superficially reticulate. Colour usually uniform black, dull, with the gaster shining. The head is usually more shiny than the alitrunk. Legs may be black, black-brown, or red-brown, and the antennal funiculi are often brown towards the apex.

Queen

Rigato (2016) - Holotype. HL 1.52, HW 1.25, CI 82, SL 1.81, SI 145, FW 0.46, FI 37, MnL 1.85, ScW 1.48, WL 2.52, HTL 1.89.

Clypeus bearing a slightly protruding, wide lobe, whose anterior margin is slightly arcuate and limited laterally by right angled corners. Head in full face view oval, wider behind than in front, posterior margin evenly convex without posterior corners; sides in front of the eyes anteriorly converging and straight. Eyes relatively large and convex. Ocelli small. Pronotal and propodeal sides immarginate. Pronotal teeth small and robust. Propodeal dorsum in dorsal view strongly transverse (at its widest point it is more the thrice as wide as medially long), arched both longitudinally and transversely. Propodeal dorsum posterolaterally with a pair of weak, distant propodeal ridges; between the ridges the propodeal dorsum smoothly merges into the declivity. Petiole with a median pair of diverging and slightly backward bent spines, whose reciprocal distance is somewhat twice the length of each spine, and a pair of shorter lateral spines, which are about half as long as the dorsal pair. First gastral tergite anteriorly concave.

Mandibles mostly smooth and shining, with superimposed elongate hair-bearing pits. Body and appendages reticulate-punctate; the sculpturation is stronger on the opaque head and mesosoma. Frons, vertex and scutum with superimposed longitudinal irregular rugulation.

The whole body and appendages with abundant, pale golden, fine standing hairs; longest hairs occur on cephalic dorsum, scapes, scutellum and gaster. Longest hairs on tibiae at most a little shorter than the maximum tibial width; longest hairs on scapes about twice as long as the maximum scape width. Pubescence pale, relatively short and abundant throughout the body, never hiding the sculpturation; on the gaster it is relatively short and moderately dense.

Body black, appendages chiefly dark brown. Mandibles apically ferrugineous as well as most of the antennal funiculi, whose 3 basalmost joints are proximally darkened.

Bolton (1973) - As worker apart from the usual differences associated with caste. The pronotal spines and propodeal teeth are reduced; the latter may even be absent.

Type Material

Rigato (2016) - Holotype gyne, SOMALIA (Revoil) (Musee National d'Histoire Naturelle) [examined].

References

  • André, E. 1887. Description de quelques fourmis nouvelles ou imparfaitement connues. Rev. Entomol. (Caen) 6: 280-298 (page 285, queen described)
  • Arnold, G. 1924. A monograph of the Formicidae of South Africa. Part VI. Camponotinae. Ann. S. Afr. Mus. 14: 675-766 (page 754, Senior synonym of natalensis)
  • Bolton, B. 1973b. The ant genus Polyrhachis F. Smith in the Ethiopian region (Hymenoptera: Formicidae). Bulletin of the British Museum (Natural History) Entomology. 28:283-369. PDF (page 338, Combination in P. (Myrma), Senior synonym of donisthorpei)
  • Emery, C. 1921e. Le genre Polyrhachis. Classification; espèces nouvelles ou critiques. Bull. Soc. Vaudoise Sci. Nat. 54: 17-25 (page 23, Combination in P. (Pseudocyrtomyrma))
  • Emery, C. 1925d. Hymenoptera. Fam. Formicidae. Subfam. Formicinae. Genera Insectorum 183: 1-302 (page 207, Combination in P. (Pseudocyrtomyrma))
  • Forel, A. 1894b. Abessinische und andere afrikanische Ameisen, gesammelt von Herrn Ingenieur Alfred Ilg, von Herrn Dr. Liengme, von Herrn Pfarrer Missionar P. Berthoud, Herrn Dr. Arth. Müller etc. Mitt. Schweiz. Entomol. Ges. 9: 64-100 (page 71, worker described)
  • Forel, A. 1916. Fourmis du Congo et d'autres provenances récoltées par MM. Hermann Kohl, Luja, Mayné, etc. Rev. Suisse Zool. 24: 397-460 (page 452, male described, Combination in P. (Myrma); page 453, Senior synonym of natalensis)
  • Rigato, F. 2016. The ant genus Polyrhachis F. Smith in sub-Saharan Africa, with descriptions of ten new species. (Hymenoptera: Formicidae). Zootaxa. 4088:1–50.
  • Shrestha B, Tanaka E, Hyun MW, Han JG, Kim CS, Jo JW, Han SK, Oh J, Sung JM, Sung GH. 2017. Mycosphere Essay 19. Cordyceps species parasitizing hymenopteran and hemipteran insects. Mycosphere 8(9): 1424–1442 (DOI 10.5943/mycosphere/8/9/8).
  • Wheeler, W. M. 1922j. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VIII. A synonymic list of the ants of the Ethiopian region. Bull. Am. Mus. Nat. Hist. 45: 711-1004 (page 999, Combination in P. (Myrma))