Polyrhachis epinotalis 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) : 17-19

Polyrhachis epinotalis Santschi stat. n.

( Figures 4 a–c)

Polyrhachis militaris st. epinotalis Santschi, 1924: 222 (in key). Lectotype worker and one paralectotype worker (by present designation), DEMOCRATIC REPUBLIC of the CONGO: Elizabethville [= Lubumbashi], ix.1911 (Miss. Agric Leplae). [First available use of Polyrhachis militaris r. cupreopubescens var. epinotalis Forel, 1913a: 357 ; unavailable name (Bolton, 1973b: 313). Junior synonym of militaris: Dorow, 1995: 36 .] (MHNG) [examined]. Stat. n.

Diagnosis. A large species in the militaris -group with relatively slender body, oval head, abundant, long and, at least partially, golden pubescence, and upturned propodeal spines.

Lectotype worker. HL 2.68, HW 2.05, CI 76, SL 3.21, SI 157, FW 0.74, FI 36, PW 1.66, WL 3.52, HTL 3.60. Anterior clypeal border medially bearing a laterally obtusely angled shallow lobe. Head in full face view oval, with moderately convex sides strongly converging to the short posterior margin. Eyes moderate in size and strongly convex. Mesosoma strongly, often flange-like marginate along its sides. Promesonotal suture well marked; metanotal suture deeply incised and narrow. Disc of pronotum and mesonotum approximately transverse; propodeal dorsum longer than wide. Pronotal spines long and sharp. Propodeal teeth long, upturned and spine-like; in profile nearly as long as the height of the propodeal declivity. Petiole with four sharp spines, the dorsal pair much longer than the lateral pair.

The entire body mostly reticulate-punctate and dull, longitudinally rugulose on occiput and vertex, including the space between eyes and frontal carinae. Mandibles finely longitudinally striolate. Pubescence abundant throughout, long and golden especially dorsally where it mostly hides the sculpturation. Standing hairs abundant on body and appendages; relatively short on antennae, longer on the legs and even longer on most of the dorsum of the body.

Integument mostly black, mostly hidden by the long and dense golden pubescence.

Paralectotype worker (same data as the lectotype). HL 2.50, HW 1.92, CI 77, SL 3.05, SI 159, FW 0.71, FI 37, PW 1.58, WL 3.48, HTL 3.40. Very similar to the Lectotype.

Other workers examined (n=12). HL 2.51–2.86, HW 1.90–2.17, CI 72–82, SL 2.95–3.52, SI 143–174, FW 0.67–0.83, FI 34–40, PW 1.54–1.88, WL 3.28–3.92, HTL 3.48–4.00.

Comment. Forel described this taxon using an unavailable name combination (a quadrinomen) and later Santschi (1924) made that name available considering epinotalis as a subspecies of militaris . I have designated as lectotype one of Forel’s syntypes at MHNG. The lectotype is in quite good condition, but misses its right foretibia and tarsus. Although considered for many years as a synonym of P. militaris , P. epinotalis is a distinct species.

Santschi (1924) pointed out the epinotalis head shape as its main distinctive feature. Principal differences separating epinotalis from militaris workers (and, in part, gynes) are as follows:

The size difference of propodeal teeth between epinotalis and militaris is usually remarkable. Forel (1913a) stated that epinotalis ’ teeth appear as upturned spines, much longer than in militaris and other related species. However, this feature is subject to some variability. In addition, epinotalis is usually more slender than militaris , with only the mesonotum distinctly transverse, but that is not always true. I examined a robust worker from Kenya (Arabuko-Sokoke Forest at HLMD) which looks militaris -like, but it has a round head and spiniform, although relatively short, propodeal teeth. Peter Hawkes (pers. comm.) faced the same difficulties with some epinotalis specimens (as well as with some slender militaris ), but confidently identified them using head and propodeal teeth shapes.

Almost all specimens I examined look relatively consistent and the species seems about as widespread as P. militaris , with which it probably co-occurs. The golden colour of the pubescence in P. epinotalis could be as variable as in militaris : some specimens look more or less greyish. The petiolar spines are slightly variable in length and the long and diverging dorsal pair is more or less apically bent backward; the lateral pair is always relatively well developed, varying from sharp teeth to short spines.

Material examined. (except types). GABON: La Makandé, Forêt des Abeilles, i–ii.1999 (A. Dejean) (1 w, BMNH). EQUATORIAL GUINEA: Bioko, 7 km N Luba, 3°27’56”N 8°29’42”E, 14.x1998 (D. Ubick, D.K. Dabney, R.W. Tomos, M. Boko, J.V. Vindum) (1 g, CAS). DEM. REP. of the CONGO: 75 mi. W of Popokabaka, 2.viii.1957 (E.S. Ross & R.E. Leech); 39 km S of Walikale, 700 m, 21.xii.1957 (E.S. Ross & R.E. Leech) (1 w, BMNH); 5 mi. S of Fizi, 1320 m, 10.i.1958 (E.S. Ross & R E. Leech) (1 w, CAS). CENTRAL AFRICAN REP.: P.N. Dzanga-Ndoki, 21.4 km 53° NE Bayanga, 3°02.01’N 16°24.57’ E, 510 m, 1–2.v.2001 (S. van Noort) (1 w, CAS: CASENT0086054 CAR01-M02); P.N. Dzanga-Ndoki, 21.4 km 53° NE Bayanga, 3°02.01’N 16°24.57’ E, 510 m, 6–7.v.2001 (S. van Noort) (1 w, CAS: CASENT0087003 CAR01-M65); P.N. Dzanga-Ndoki, 21.4 km 53° NE Bayanga, 3°02.01’N 16°24.57’ E, 510 m, 7.v.2001 (S. van Noort) (1 w, CAS: CASENT0090853 CAR01-S91); P.N. Dzanga-Ndoki, 38.6 km 173° S Lidjombo, 2°21.60’N 16°03.20’E, 350 m, 21–27.v.2001 (S. van Noort) (1 w, CAS: CASENT0094892 CAR01-Y67). UGANDA: Kampala Tank Hill, 7–10.vii.1987 (V. Ferri) (4 w, MSNM); Entebbe, Entebbe Botanical Gardens, 17–22.viii.2012, 0°03’52.61”N 32°28’40.50”E, 1143 m, on tree (F. Hita Garcia) (3 w, HLMD). RWANDA: 40 km E of Kigali, 1575 m, 9.xii.1957 (E.S. Ross & R.E. Leech) (1 w, BMNH). KENYA: Kaimosi Mission, 27 mi. NE of Kisumu, 1650m, 29.xi.1957 (E.S. Ross & R.E. Leech) (1 w, BMNH); Kakamega, 28.iii.1976 (W. Gotwald & R. Schefer) (2 w, BMNH); Malindi district, Arabuko-Sokoke forest, 3.29°S 39.98°E, 10–15 m el., 31.v.2001, #01-438, 2nd hardwood forest nr “Tree-House”, foraging in litter (R.R. Snelling & D.J. Martins) (1 w, HLMD); Western Province, Kakamega Forest, Udo’s camp, kitchen band, 1650 m, vi.2008, daytime hand collected (F. Hita Garcia) (1 g, HLMD); Western Province, Kakamega Forest, Colobus primary forest, 0°21’16”N 34°51’36”E, 1650 m, vii.2008, handcoll. (G. F i s c h er) (1 w, HLMD); Western Province, Kakamega Forest, Mwanzu Trail, 0°14’15.5”N 34°52’03.2”E, 1650 m, prim. Forest, 11.viii.2008, from ground, hand collected (G. F i s c h e r) (5 w, HLMD). ZAMBIA: North Western Prov., Ikelenge, Hillwood Farm, 11°14’57.45”S 24°18’50.82”E, 1392 m, hand coll., viii.2008 (R. van den Elzen) (3 w, HLMD).

Figures

FIGURE 4. Polyrhachis epinotalis, worker (CENTRAL AFRICAN REP., P. N. Dzanga-Ndoki, 21.4 km 53 ° NE, Bayanga, 3 ° 02.01 ’ N 16 ° 24.57 ’ E, 510 m, 6 – 7. v. 2001 (S. van Noort), CAR 01 - M 56 - CAR 01 - M 66 [CASENT 0087003 CAR 01 - M 65]): A, body profile; B, dorsum of mesosoma; C, head in full-face view. (Photos by M. Zilioli)