Polyrhachis weissi Santschi

Rigato, Fabrizio, 2016, The ant genus Polyrhachis F. Smith in sub-Saharan Africa, with descriptions of ten new species. (Hymenoptera: Formicidae), Zootaxa 4088 (1) : 44-45

Polyrhachis weissi Santschi

Polyrhachis weissi Santschi, 1910: 395 . Holotype worker, CONGO: Brazzaville (A. Weiss) (NHMB).

Polyrhachis natalensis Santschi, 1914: 41 . Syntype workers, SOUTH AFRICA: Natal, Stamford Hill, 25.i.1905 (NHMB). Syn. n.

Polyrhachis revoili var. conduensis Forel, 1915: 351 . Syntype workers, DEMOCRATIC REPUBLIC of the CONGO: Kasai, Kondue (E. Luja) (MHNG) [synonymy by Bolton, 1973: 342].

Polyrhachis revoili var. donisthorpei Forel, 1916: 453 . Syntype workers, NORTH RHODESIA [= ZAMBIA] (MHNG) [synonymized with P. revoili by Bolton, 1973: 338]. Syn. n.

Polyrhachis revoili subsp. crassa Emery, 1921: 23. Syntype worker and gyne, CAMEROUN, 1895 (L. Conradt) (MSNG) [synonymy by Bolton, 1973: 342].

Polyrhachis revoili subsp. crassa var. phaenogaster Emery, 1921: 24 . Syntype worker and gyne, CAMEROUN, 1895 (L. Conradt) (MSNG) [referred to P. weissi by Bolton, 1973: 342]. [unavailable name]

Polyrhachis revoili subsp. balli Santschi, 1939: 10. Syntype workers, DEMOCRATIC REPUBLIC of the CONGO: Gazi, xii.1937 (Beinaert) (NHMB) [synonymized by Bolton, 1973: 342 under P. we i s s i].

Diagnosis. 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.

Comment. Bolton (1973: 339) separated P. weissi Santschi from P. revoili André on “quite trivial” (in Bolton’s own words) characters: size, pilosity and sculpturation; he also gave them an allopatric distribution. Bolton’s revoili has strongly hairy scapes, is larger and more irregularly sculptured and was reported as occurring in eastern and southern Africa. On the contrary, the west and central African weissi has hairless or almost hairless scapes, a more regular sculpturation and smaller size. However, it must be pointed out that worker and gyne syntypes of P. revoili subsp. crassa Emery, synonymized with weissi by Bolton (1973), come from Cameroon and have as abundantly hairy scapes as Bolton’s revoili . Consequently, crassa should belong to revoili ‘sensu Bolton’ and its collecting locality also denies the allopatry between weissi and revoili .

Bolton’s revoili , weissi and all of their synonyms share the diagnostic features reported above and cannot be conspecific with P. revoili André (see under that heading). For this reason and because I could not see any consistent difference of size, sculpturation and pubescence, I assign all of them to weissi . However, 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.

Material examined. Scapes with 0 – <10 standing hairs. CENTRAL AFRICAN REP.: P.N. Dzanga-Ndoki, Mabéa Bai, 21.4 km 53° NE Bayanga, 3°02’N 16°25’E, 510 m, 1–7.v.2001 #4004 (B.L. Fisher) (1g, CAS: CASENT0415886); Res. Dzanga-Sangha, 12.7 km 326° NW Bayanga, 3°00’N 16°12’E, 420 m, 10–17.v.2001 #4083 (B.L. Fisher) (1 w, CAS: CASENT0081187); Res. Dzanga-Sangha, 12.7 km 326° NW Bayanga, 3°00’N 16°12’E, 420 m, 10–17.v.2001 #4123 (B.L. Fisher) (1 w, CAS: CASENT0403724); Res. Dzanga-Sangha, 12.7 km 326° NW Bayanga, 3°00’N 16°12’E, 470 m, 10–17.v.2001 #4087 (B.L. Fisher) (1 g, 11 w, CAS: CASENT0403857, CASENT0403891, CASENT0403945, CASENT0403958, CASENT0404012, CASENT0404014, CASENT0404030, CASENT0404062, CASENT0404069); Res. Dzanga-Sangha, 12.7 km 326° NW Bayanga, 3°00.27’N 16°11.55’E, 420 m, 11.v.2001 (S. van Noort) (1 w, CAS: CASENT0090751 CAR01-S109); Res. Dzanga-Sangha, 12.7 km 326° NW Bayanga, 3°00.27’N 16°11.55’E, 420 m, 13.v.2001 (S. van Noort) (1 w, CAS: CASENT0091738 CAR01-S151); Res. Dzanga-Sangha, 12.7 km 326° NW Bayanga, 3°00.27’N 16°11.55’E, 420 m, 15.v.2001 (S. van Noort) (3 w, CAS: CASENT0091280 CAR01-S182, CASENT0091342 CAR01-S187, CASENT0092075 CAR01-S190); Res. Dzanga-Sangha, 12.7 km 326° NW Bayanga, 3°00.27’N 16°11.55’E, 420 m, 16–17.v.2001 (S. van Noort) (1 w, CAS: CASENT0087509 CAR01-M151); Res. Dzanga- Sangha, 12.7 km 326° NW Bayanga, 3°00.27’N 16°11.55’E, 420 m, 17.v.2001 (S. van Noort) (1 g, 1 w, CAS: CASENT0092087 CAR01-S191, CASENT0092184 CAR01-S199).

Scapes with> 30 standing hairs. REPUBLIC of the CONGO: Niari Region, 2.30757 S 12.82985 E, 660 m, 3.vii.2013, primary forest, canopy fogging, (L. Niemand) (3 w, AFRC: CASENT0250020, CASENT0250023, CASENT0250032); Niari Region, 2.30339 S 12.83902 E, 705 m, 3.vii.2013, primary forest, canopy fogging, (L. Niemand) (1 g, AFRC: CASENT0250024); Niari Region, 2.31500 S 12.82488 E, 710 m, 5.vii.2013, primary forest, canopy fogging, (L. Niemand) (2 w, AFRC: CASENT0250016, CASENT0250017). SOUTH AFRICA: Kwazulu Natal, Umtamvuna Nature Reserve, 31°03.506’S 30°10.392’E, 160 m, 15 16.xi.2000 (S. van Noort) malaise trap, coastal forest (1 w, CAS: CASENT0099660 KW00-M74); Kwazulu Natal, Umtamvuna Nature Reserve, 31°03.506’S 30°10.392’E, 160 m, 17.xi.2000 (S. van Noort) sweep coastal forest (2 g, 6 w, CAS: CASENT0098295 KW00-S21, CASENT0098360 KW00-S30, CASENT0098382 KW00-S33, CASENT0098385 KW00-S34, CASENT0098386 KW00-S34, CASENT0098395 KW00-S35, CASENT0098398 KW00-S36, CASENT0098429 KW00-S39).