Polyrhachis weissi

P. weissi may be regarded as the forest equivalent of revoili, which appears to be confined to savannah and veldt regions. Nests of silk and vegetable particles are constructed under leaves or between contiguous leaves which are gummed together by the silk. A small nest dissected at CRIG, New Tafo in July 1970 by P. M. Room contained seven workers, six females (all alate), five males, and 32 brood (larvae and pupae). (Bolton 1973)

Identification
Rigato (2016) - Polyrhachis weissi looks easily identifiable within the revoili-group for this unique combination of features: 1) clypeus with an uniformly rounded anterior margin; 2) head in full face view distinctly trapezoidal with a strongly transverse, weakly convex posterior border; 3) eyes moderately convex and placed close to posterior corners; 4) mesosoma fully immarginate and stout (in dorsal view pronotum and mesonotum strongly transverse, propodeal dorsum trapezoidal, much wider in front than behind and distinctly shorter than its maximum width); 5) propodeal dorsum bearing a pair of small, sharp upturned teeth at its posterior corners; 6) petiole with two pairs of spines, the mid pair slightly curved backward and distinctly longer; 7) body mostly reticulate punctate with superimposed fine longitudinal rugulae on cephalic and mesosomal dorsa (cephalic rugulae tidier); 8) standing hairs moderately long and abundant all over the body and legs, mostly yellowish in colour.

The presence and number of standing hairs on scapes could suggest the existence of two distinct species. Some nest series have 0 to few standing hairs on scapes, whereas other samples have more than 30, without any seemingly intermediate condition. Because of lack of further reliable distinctive characters, I prefer to consider these alternative conditions as a matter of intraspecific variability.

Distribution based on Regional Taxon Lists
Afrotropical Region: Cameroun, Central African Republic, Congo, Democratic Republic of Congo, Ghana, Guinea, South Africa, Zambia.

Biology
Alate females have been recorded from Ghana in July.

Nomenclature

 *  weissi. Polyrhachis weissi Santschi, 1910c: 395, fig. 18 (w.) CONGO. Combination in P. (Pseudocyrtomyrma): Emery, 1925b: 207; in P. (Myrma): Wheeler, W.M. 1922a: 1004; Bolton, 1973b: 342. Subspecies of revoili: Forel, 1916: 453; Emery, 1925b: 207; Santschi, 1939c: 12. Status as species: Wheeler, W.M. 1922a: 1004; Bolton, 1973b: 342. Senior synonym of balli, conduensis, crassa and material of the unavailable name phaenogaster referred here: Bolton, 1973b: 342.
 * conduensis. Polyrhachis (Myrma) revoili var. conduensis Forel, 1915c: 351 (w.) DEMOCRATIC REPUBLIC OF CONGO. Combination in P. (Pseudocyrtomyrma): Emery, 1925b: 207. Junior synonym of weissi: Bolton, 1973b: 342.
 * crassa. Polyrhachis (Pseudocyrtomyrma) revoili subsp. crassa Emery, 1921e: 23, fig. 2 (w.q.) CAMEROUN. Junior synonym of weissi: Bolton, 1973b: 342.
 * balli. Polyrhachis (Pseudocyrtomyrma) revoili st. balli Santschi, 1939c: 10 (w.) DEMOCRATIC REPUBLIC OF CONGO. Junior synonym of weissi: Bolton, 1973b: 342.
 * natalensis. Polyrhachis natalensis Santschi, 1914e: 41 (w.) SOUTH AFRICA. Combination in P. (Myrma): Wheeler, W.M. 1922a: 999; in P. (Pseudocyrtomyrma): Emery, 1925b: 207. Status as species: Wheeler, W.M. 1922a: 999. Subspecies of revoili: Emery, 1925b: 207; Santschi, 1939c: 12. Junior synonym of revoili: Forel, 1916: 453; Arnold, 1924: 754; Bolton, 1973b: 338; of weissi: Rigato, 2016: 44.
 * donisthorpei. Polyrhachis (Myrma) revoili var. donisthorpei Forel, 1916: 453 (w.) ZAMBIA. [Also described as new by Forel, 1917: 252.] Combination in P. (Pseudocyrtomyrma): Emery, 1925b: 207. Junior synonym of revoili: Bolton, 1973b: 338; of weissi: Rigato, 2016: 44.

Worker
Bolton (1973) - TL 5.7-6.1, HL 1.40-1.48, HW 1.29-1.40, CI 88-95, SL 1.66-1.74, SI 124-125, PW 1.18-1.26, MTL 1.59-1.66. (15 measured.)

Anterior clypeal margin arcuate and entire. Eyes convex, the sides of the head gently convex and convergent anteriorly. Alitrunk not marginate, the dorsum convex. Promesonotal suture faint but distinct, the metanotal groove reduced to a line which only breaks the sculpturation. Pronotum very broad, more than twice the width of the propodeum measured across the teeth. Pronotum armed with a pair of short, acute spines of somewhat variable configuration; the propodeum with a pair of small, upcurved teeth. Petiole with two pairs of spines, the dorsal pair long and acute, the laterals much shorter and weakly upcurved. Anterior face of the first gastral segment shallowly concave medially.

Head and body with numerous erect hairs, white to grey in colour. Hairs very sparse or absent from the antenna! scapes. Pubescence everywhere sparse, short, greyish in colour, nowhere concealing the underlying sculpturation.

Head and entire dorsum of alitrunk finely, longitudinally striate-rugose. Gaster finely and superficially reticulate. Colour uniform black, or with the appendages somewhat lighter, either dark brown or red-brown. Antennal funiculi usually with the apical five or six segments light brown.

Queen
Bolton (1973) - As worker but with the pronotal spines reduced to mere teeth and the propodeal teeth minute or absent. The sculpturation of the mesoscutum tends to be notably finer than that of the head.

Type Material
Rigato (2016) - Holotype worker, CONGO: Brazzaville (A. Weiss).

References based on Global Ant Biodiversity Informatics

 * Belshaw R., and B. Bolton. 1994. A survey of the leaf litter ant fauna in Ghana, West Africa (Hymenoptera: Formicidae). Journal of Hymenoptera Research 3: 5-16.
 * Belshaw R., and B. Bolton. 1994. A survey of the leaf litter ant fauna in Ghana, West Africa (Hymenoptera: Formicidae). Journal of Hymenoptera Research. 3: 5-16.
 * Bolton B. 1973. The ant genus Polyrhachis F. Smith in the Ethiopian region (Hymenoptera: Formicidae). Bulletin of the British Museum (Natural History). Entomology 28: 283-369.
 * Dejean A., F. Azemar, R. Cereghino, M. Leponce, B. Corbara, J. Orivel, and A. Compin. 2015. The dynamics of ant mosaics in tropical rainforests characterized using the SelfOrganizing Map algorithm. Insect Science doi: 10.1111/1744-7917.12208
 * 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.
 * Robson Simon Database Polyrhachis -05 Sept 2014
 * Santschi F. 1910. Formicides nouveaux ou peu connus du Congo français. Annales de la Société Entomologique de France 78: 349-400.
 * Tadu Z., C. Djieto-Lordon, R. Babin, Yede, E. B. Messop-Youbi, and A. Fomena. 2013. Influence of insecticide treatment on ant diversity in tropical agroforestry system: some aspect of the recolonization process. International Journal of Biodiversity and Conservation 5(12): 832-844.
 * Taylor B. 1978. Ants of the Nigerian Forest Zone (Hymenoptera: Formicidae). II. Formicinae, Dolichoderinae. Cocoa Research Institute of Nigeria Research Bulletin 5: 1-57.
 * Wheeler W. M. 1922. 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. Bulletin of the American Museum of Natural History 45: 711-1004