Pheidole bula Sarnat, 2008

Sarnat, E. M., 2008, A taxonomic revision of the Pheidole roosevelti-group (Hymenoptera: Formicidae) in Fiji., Zootaxa 1767, pp. 1-36 : 12-17

Pheidole bula Sarnat sp. n.

Figs. 32-34, 53-55, 74-76

Holotype major, FIJI: Viti Levu, Mt. Tomanivi 3.4 km E Navai Village , 1.ii.2005, 1320m, -17.61481°, 178.01825°, exposed mountain summit, nesting under stone, (E. M. Sarnat), EMS#1789, CASENT0171113 ( FNIC) .

Paratypes. From same nest series as holotype: 2 alate queens (CASENT0174000, CASENT0171114), 1 dealate queen (CASENT0174003), 2 males (CASENT0174008, CASENT0171115), 4 majors (CASENT0174001, CASENT0174004, CASENT0174006, CASENT0174009), 5 minors (CASENT0171017, CASENT0174002, CASENT0174005, CASENT0174007, CASENT0174010) ( FNIC, NMNH, ANIC); additional specimens in alcohol ( NMNH).

MAJOR. TL 5.60-6.27, HL 2.06-2.14, HW 2.05-2.12, CI 0.93-0.99, FL 1.51-1.57, FI 0.69-0.71, SL 1.09-1.12, SI 0.49-0.52 (5 measured).

Head distinctly broader behind eyes than in front of eyes. Median ocellus absent in type series. Mesonotal process produced as a thick lamellate plate overhanging propodeum, slightly upturned apically; in dorsal view attachment to mesonotum broad, posterior margin flat to weakly excised. Propodeal spines maintaining an evenly stout thickness for basal 4/5 length whereupon the anterior edge angles obliquely towards the posterior edge to form an acuminate tip. In posterior view, petiole node deeply excised. Postpetiole taller than long; as tall as petiole; steep anterior and posterior faces converging to form an obtusely angulate vertex; in dorsal view subpentagonal with modest lateral projections.

Region between frontal carinae with straight longitudinal carinae branching into reticulate network on vertex and full length of posterolateral lobes; intercarinular spaces smooth and shining to shallowly impressed. Eye surrounded by elevated rugoreticulum. Antennal scrobe smooth and shining in some specimens, overlain by short discontinuous rugae in others. Clypeus mostly smooth and shining; anterior margin with several short carinae in addition to those extending from frontal lobes, median carinae weak to absent. Lateral portions of posterolateral lobes with a smooth and shining patch surrounded by sculpture. Head venter densely rugoreticulate. Promesonotum rugoreticulate. Anepisternum weakly rugose. Katepisternum mostly smooth and shining, occasionally with weak carinae. Petiole with anterior and posterior faces smooth, laterally and ventrally rugose. Postpetiole dorsum smooth and shining, sides rugose. First tergite of gaster with basal sculpture short and weak to absent. First sternite of gaster lightly sculptured laterally. Gaster otherwise smooth and shining. Body dark reddish-brown with lighter appendages.

MINOR. TL 3.60-3.92, HL 0.81-0.89, HW 0.70-0.78, CI 0.87-0.90, FL 1.08-1.23, FI 1.26-1.39, SL 0.97-1.08, SI 1.16-1.25, AE 0.27-0.31, DE 0.17-0.20, PSI 0.55-0.68 (8 measured).

Head, in full face view, subquadrate, sides weakly convex, posterolateral corners rounded and weakly obtuse, posterior margin flat to convex expect where weakly excised medially; in profile, posterior margin dorsoventrally pinched where dorsum and venter join at an obtuse angle. Genal carinae strongly produced as elevated flanges on ventrolateral portion of head that weaken before joining together medially. Clypeus with anterior margin convex laterally, flat to weakly convex medially. Frontal carinae terminating near eye level. Mesonotal process produced as a short lamellate plate with upwardly deflected margins; in dorsal view, attachment to mesonotum broad, posterior margin convex to excised. Propodeal spines thickening apically into a bifurcation with a short blunt anterior point and a long acuminate posterior point that projects at an oblique angle; length of dorsal edge less than length of anterior edge.

Head medially smooth and shining with discontinuous and occasionally branching carinae, laterally and ventrally rugoreticulate. Clypeus with a few weak carinae attached to anterior border. Promesonotum, in dorsal view, mostly smooth and shining with a few weak and discontinuous transverse rugae. Anepisternum rugose. Katepisternum mostly smooth and shining. Dark reddish-brown with slightly lighter appendages.

QUEEN. TL 5.85-6.36, HL 1.27-1.31, HW 1.28-1.29, CI 0.98-1.01, SL 1.00-1.01, SI 0.76-0.80, FL 1.02-1.04, FI 0.78-0.79, ML 0.71-0.76, MI 0.55-0.59 (3 measured).

Head subquadrate with sides approximately as wide anteriorly as posteriorly. Mesoscutum, in profile, small, less than half height of pronotum; in dorsal view, not obscuring pronotum. Scutellum, in dorsal view, with posterior portion produced as a weakly elevated circular plate. Propodeal spines maintaining an evenly stout thickness for basal 4/5 length whereupon the anterior edge angles obliquely towards the posterior edge to form an acuminate tip. Petiole broadly cuneate; in posterior view, petiole node flat to weakly concave. Postpetiole, in dorsal view, subpentagonal with modest lateral projections.

Region between frontal carinae with irregular longitudinal carinae that occasionally branch; intercarinular spaces smooth and shining to shallowly impressed. Head with lateral and ventral regions rugoreticulate. Antennal scrobe smooth and shining, overlain by short discontinuous rugae. Clypeus mostly smooth and shining; anterior margin with short carinae laterally, median carinae absent. Pronotum rugoreticulate. Mesoscutum, in dorsal view, with discontinuous rugae medially and long arcuate rugae laterally that curve towards median as they approach posterior margin. Scutellum mostly smooth and shining. Anepisternum rugoreticulate. Katepisternum mostly smooth and shining with weak rugulae. Petiole sculptured laterally, ventrally and on posterior face. Postpetiole longitudinally rugulose. First tergite of gaster longitudinally striate basally. First sternite of gaster with dense mat of fine sculpture basally. Body dark reddish-brown with lighter appendages.

Etymology. Bula is the Fijian word for ‘life’ and serves as the ubiquitous greeting among Fijians.

Diagnosis, distribution and biology. Pheidole bula is one of the smaller members of the P. roosevelti group, and is endowed with modestly projecting spines and strong sculpturing. The species is most readily distinguished from its close relatives by the smooth and shining spaces between its facial rugae. While P. roosevelti and P. furcata both have facial rugoreticulum (majors) or rugae (minors) similar to P. bula , the interspaces between their rugae are filled with densely packed foveolae, giving them a duller appearance. The minor worker can be separated from all other minors of P. roosevelti-group by the strong sculpturing of the ventral surface of its head. While the rugoreticulate face of P. bula is similar to P. roosevelti , the small queen and morphometric measurements suggest closer relationship to P. furcata from Kadavu and P. colaensis , which also occurs on Mt. Tomanivi.

Although P. colaensis was encountered with relative frequency throughout the higher elevations of Mt. Tomanivi (Fiji’s tallest mountain), P. bula was encountered only at the mountain’s summit. The population of P. bula may therefore be in a precarious situation. With perhaps its closest extant relative occupying the lower elevations, and with no higher elevation to retreat to, it is possible that the current trends in climate change will consign P. bula to extinction in the near future.

Additional material examined. FIJI. Viti Levu: Mt. Tomanivi 3.4 km E Navai Village , 1.ii.2005, 1320m, -17.61481°, 178.01825°, moss forest, from sifted leaf litter, (E. M. Sarnat), EMS#1791-5, 3 minors (CASENT0174011 - CASENT0174013) ; Mt. Tomanivi 3.4 km E Navai Village , 1.ii.2005, 1320m, - 17.61481°, 178.01825°, exposed mountain summit, ground foraging, (E. M. Sarnat), EMS#1787, 3 minors (CASENT0174014 - CASENT0174016) ; Mt. Tomanivi summit , 27.viii.2006, 1320m, -17.61481°, 178.01825°, mossy rainforest and clearing, ground nest in moss mat, (P. S. W a r d), PSW#15754 .