Pheidole pegasus Sarnat, 2008

Sarnat, E. M., 2008, A taxonomic revision of the Pheidole roosevelti-group (Hymenoptera: Formicidae) in Fiji., Zootaxa 1767, pp. 1-36 : 21-22

Pheidole pegasus Sarnat sp. n.

Fig. 41-43, 62-64, 83-85

Holotype major, FIJI: Vanua Levu, Mt. Delaikoro 4.3 km SE Dogoru Village , 31.vii.2006, 910m, -16.59028°, 179.31580°, high elevation moss forest, from turret nest in bare soil, (E. M. Sarnat), EMS#2370, CASENT0171108, ( FNIC).

Paratypes. From same nest series as holotype: 1 dealate queen (CASENT0171109), 2 majors (CASENT0171108, CASENT0174264, CASENT0174267), 10 minors (CASENT0171024, CASENT0174265, CASENT0174266, CASENT0174268 - CASENT0174275), ( FNIC, NMNH, ANIC, LACM); additional specimens in alcohol ( NMNH).

MAJOR. TL 6.45-6.98, HL 2.18-2.37, HW 2.20-2.35, CI 0.98-0.99, FL 1.59-1.66, FI 0.70-0.73, SL 1.15-1.19, SI 0.50-0.53 (2 measured).

Head with sides distinctly broader behind eyes than in front of eyes. Median ocellus present in two of the three specimens examined. Mesonotal posterior process produced as a thick, upturned plate overhanging propodeum, in dorsal view attachment to mesonotum broad, posterior margin flat to excised. Propodeal spines, in profile, with posteriorly projecting dorsal edge as long as or longer than anterior edge. Petiole node, in posterior view, with dorsum and sides deeply excised. Postpetiole taller than long; shorter than petiole; steep anterior and posterior faces converging to form an obtusely angulate vertex; in dorsal view subpentagonal with strong lateral projections.

Region between frontal carinae with straight longitudinal carinae that extend onto the posterolateral lobes; intercarinular spaces smooth and shining. Eye surrounded by elevated carinae. Antennal scrobe smooth and shining. Clypeus mostly smooth and shining; anterior margin with several carinae extending to frontal lobes; median carina weak to absent. Posterolateral portion of posterolateral lobes smooth and shining. Head venter rugose. Promesonotum transversely rugose. Anepisternum weakly rugose. Katepisternum mostly smooth and shining, occasionally with weak striae. Petiole with apical and posterior faces smooth, laterally and ventrally rugose. Postpetiole anterior face with weak transverse striae; dorsum and posterior face smooth with a few weak transverse carinae. Gaster striate-foveolate on basal fifth of first segment; sternite of first segment with arcuate striae; elsewhere smooth and shining. Body reddish-brown with lighter appendages.

MINOR. TL 3.91-4.39, HL 0.90-0.97, HW 0.83-0.89, CI 0.92-0.96, FL 1.38-1.42, FI 1.45-1.56, SL 1.21-1.27, SI 1.29-1.39, AE 0.29-0.33, DE 0.46-0.50, PSI 1.46-1.71 (9 measured).

Head, in full face view, subquadrate, sides convex, posterolateral corners rounded and obtuse, posterior margin flat laterally and concave medially; in profile, posterior margin strongly dorsoventrally pinched where dorsum and venter join at an acute angle. Genal carinae produced as a weakly elevated collar surrounding ventral foramen. Clypeus with anterior margin convex laterally and flat to weakly concave medially. Frontal carinae weak and terminating before eye level. Mesonotal process produced as a lamellate plate with upwardly deflected margins; in dorsal view, attachment to mesonotum broad, posterior margin moderately to strongly concave. Propodeal spines thickening apically into a bifurcation with a short anterior point or angle, and a long acuminate posterior point that projects at an oblique angle; length of dorsal edge approximately 1.5 times length of anterior edge.

Head smooth and shining on all surfaces. Clypeus occasionally with a few weak carinae attached to anterior border. Promesonotum, in dorsal view, mostly smooth and shining with a few very weak transverse impressions. Anepisternum smooth and shining. Katepisternum smooth and shining. Metapleuron smooth and shining with single carinae bordering metapleural gland. Head and mesosoma reddish-brown; waist, gaster and legs paler.

QUEEN. TL 8.77, HL 1.73, HW 1.95, CI 1.13, SL 1.24, SI 0.72, FL 1.67, FI 0.97, ML 0.73, MI 0.88 (1 measured).

Head subcordate with sides conspicuously narrower anteriorly than posteriorly. Mesoscutum, in profile, massive, approximately equal height as pronotum; in dorsal view, obscuring pronotum. Scutellum, in dorsal view, with posterior portion produced as a weakly elevated subtriangular plate. Propodeal spines with strongly projecting dorsal edge subequal in length to anterior edge. Petiole broadly cuneate; in posterior view, petiole node broad with strongly concave dorsum and moderately concave sides. Postpetiole, in dorsal view, subpentagonal with strong lateral projections.

Region between frontal carinae with straight longitudinal carinae that reach posterior margin. Region between eyes and antennal insertions with elevated carinae that continue to posterolateral corners; intercarinular spaces smooth and shining. Head venter with arcuate carinae bending toward median. Antennal scrobe smooth and shining. Clypeus mostly smooth and shining; anterior margin with short carinae laterally, median carinae present. Pronotum rugose and rugoreticulate. Mesoscutum, in dorsal view, with straight carinae that run posteriorly towards median. Scutellum densely rugose. Anepisternum rugose dorsally. Katepisternum rugose anteriorly. Petiole rugulose. Postpetiole rugulose. First tergite of gaster longitudinally sculptured basally, sculpture immediately posterior to postpetiole longer than length of postpetiole. First sternite of gaster sculptured basally. Dark reddish-brown with lighter appendages.

Etymology. The specific epithet pegasus is a noun in apposition in reference to the horse beast of Greek mythology, whose wings bear resemblance to the extraordinary propodeal spines of this species.

Diagnosis, distribution and biology. Pheidole pegasus , on account of its large size, long limbs, glassy integument, and extraordinarily long propodeal spines, is arguably the most distinctive species of the roosevelti group. The only species that it can be confused with is P. uncagena , with which it is sympatric. The major of P. pegasus can be distinguished from that of P. uncagena by the long dorsal edge of the propodeal spine and a broadly attached mesonotal process. The most distinctive differences between the minors of the two species, besides the longer spines and limbs of P. pegasus , are both found on the head. Whereas P. pegasus has a strongly ventrodorsally flattened subquadrate head and inconspicuous genal carinae, the head of P. uncagena is subovate, less flattened, and bears genal carinae that are produced conspicuously as elevated flanges.

Although P. pegasus is known only from the summit of Mt. Delaikoro, the species may occur on other tall peaks of Vanua Levu that remain unexplored. Where it does occur, it is locally abundant. The single turret of the nest belonging to the type series had a 5mm diameter entrance hole, and was also insulated by a tidy ring of vegetation debris apparently placed there by workers. The queens of the species are large, with strongly developed mesosomas.