Polyrhachis medusa

An individual was hand collected in primary forest. Little else is known of this species' biology.

Identification
A member of the Polyrhachis militaris species-group. Bolton (1973) - Closely related to Polyrhachis schistacea, from which it may be separated by the extremely dense clothing of long hairs and the density of the pubescence, which conceals the fine superficially reticulate sculpturation. Casual observation may possibly confuse this species with more densely hairy individuals of Polyrhachis militaris, but the characters quoted under couplet 45 of the key to species will serve to discriminate the two.

Distribution based on Regional Taxon Lists
Afrotropical Region: Kenya, Mozambique, United Republic of Tanzania.

Biology
Bolton (1973) - Alate females have been recorded from Tanzania in May and September. Due to its large size and affinities one would expect it to be a ground nesting species as Polyrhachis schistacea. Santschi (1914a:140) noted there is a large Clubionid spider, “probably Apochinomma formicaeforme Pavesi”, which mimics medusa.

Nomenclature

 *  medusa. Polyrhachis schistacea r. medusa Forel, 1897c: 206 (w.q.m.) TANZANIA. Combination in P. (Myrma): Santschi, 1914b: 140. Subspecies of schistacea: Forel, 1901h: 78; Wheeler, W.M. 1922a: 1002. Raised to species: Forel, 1907g: 92; Santschi, 1914b: 140; Emery, 1925b: 199. See also: Bolton, 1973b: 312.

Worker
Bolton (1973) - TL 12.6-14.4, HL 2.74-3.00, HW 2.40-2.52, CI 84-88, SL 3.37-3.56, SI 139-142, PW 2.24-2.52, MTL 3.51-3.70. (13 measured.)

Anterior clypeal margin straight to shallowly and broadly concave. Eye shape ranging from weakly concave to weakly convex but usually more or less flat. Sides of head and occipital margin convex; the eyes when flat not breaking the outline of the sides of the head in full-face view. Alitrunk marginate throughout its length, the marginations interrupted at the promesonotal suture and the impressed metanotal groove. Pronotal spines long, narrow and weakly incurved; propodeal armament reduced to a pair of blunt tubercles. The margination of the mesonotum and propodeum is often irregular, giving a chipped and jagged appearance in dorsal view. Dorsal surfaces of alitrunk transverseiy convex. Petiole with a pair of spines at the dorsolateral angles and a pair of laterally placed strong, acute teeth.

Head, body and appendages densely clothed with long, erect white hairs, some of which are curved or sinuate. Pubescence everywhere long and dense, white or off-white in colour and completely hiding the sculpturation.

Sculpturation everywhere of a very fine, superficial reticulation (revealed by scraping off the pubescence). Colour black, but specimens have a greyish appearance due to the very dense pubescence.

Queen
Bolton (1973) - As worker, with the usual differences associated with this caste. Propodeum not marginate, the dorsum rounding into the sides.

Type Material
Bolton (1973) - Syntype workers, queen, male, TANZANIA: Zanzibar (A. Voeltzkow).