Pheidole colaensis Mann

Sarnat, E. M., 2008, A taxonomic revision of the Pheidole roosevelti-group (Hymenoptera: Formicidae) in Fiji., Zootaxa 1767, pp. 1-36 : 17-18

Pheidole colaensis Mann

Figs. 35-37, 56-58, 77-79

Pheidole colaensis Mann , 1921: 441. Syntypes, 2 majors, 4 minors. FIJI: Viti Levu, Nadarivatu , (W. M. Mann), ( MCZ, examined; NMNH, examined) .

MAJOR. TL 5.78-7.06, HL 1.91-2.19, HW 1.77-2.01, CI 0.88-0.93, FL 1.33-1.49, FI 0.65-0.70, SL 0.94- 1.05, SI 0.46-0.49 (9 measured).

Head with sides not distinctly broader posterior to eyes than anterior to eyes. Median ocellus present and well-developed in all specimens examined. Mesonotal posterior process produced as a thick slightly upturned lamellate plate overhanging propodeum; in dorsal view attachment to mesonotum broad, posterior margin flat to 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 moderately 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 extending onto vertex and terminating before reaching entirely smooth and shining posterolateral lobes; intercarinular spaces smooth and shining. Elevated carinae between eye and antennal insertion, eye and mandible insertion, and ventrad of eye. Antennal scrobe smooth and shining. Clypeus smooth and shining; carinae extend from anterior margin to frontal lobes. Lateral and ventrolateral portions of posterolateral lobes entirely smooth and shining, posteriorly with shallow oblong impressions. Head venter rugose. Promesonotum with weak transverse rugae. Anepisternum weakly rugose. Katepisternum entirely smooth and shining. Petiole with apical and posterior faces smooth, laterally and ventrally rugose. Postpetiole dorsum mostly smooth and shining, sides rugose. First tergite of gaster with sculpture short and weak to absent. First sternite of gaster lightly sculptured laterally at base. Gaster otherwise smooth and shining. Body reddish-brown with lighter appendages.

MINOR. TL 3.34-3.90, HL 0.78-0.88, HW 0.68-0.81, CI 0.88-0.93, FL 1.12-1.23, FI 1.37-1.48, SL 0.99-1.06, SI 1.18-1.28, AE 0.27-0.31, DE 0.08-0.22, PSI 0.29-0.77 (8 measured).

Head, in full face view, subquadrate, sides convex, posterolateral corners rounded and 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 produced as an inconspicuous collar surrounding ventral foramen. Clypeus with anterior margin convex laterally, flat to weakly convex medially. Frontal carinae terminating near eye level. Mesonotal process produced as a lamellate plate with upwardly deflected margins; in dorsal view, attachment to mesonotum broad, posterior margin excised. Propodeal spines thickening apically into a weak bifurcation with a short anterior point or blunt angle, and a long acuminate posterior point that projects at an oblique angle; length of dorsal edge less than length of anterior edge.

Head entirely smooth and shining except for weak longitudinal carinae below level of eyes. Clypeus with a few weak carinae attached to anterior border. Promesonotum, in dorsal view, smooth and shining. Anepisternum rugose. Katepisternum mostly smooth and shining. Reddish-brown with slightly lighter appendages.

QUEEN. TL 6.44-6.77, HL 1.27-1.30, HW 1.29-1.35, CI 1.02-1.03, SL 0.99, SI 0.76-0.78, FL 1.34- 1.35, FI 1.04-1.05, ML 0.55-0.57, MI 0.86-0.89 (2 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 concave. Postpetiole, in dorsal view, subpentagonal with modest lateral projections.

Region between frontal carinae with straight unbranching longitudinal carinae terminating before obtaining posterior margin; intercarinular spaces smooth and shining. Region between eyes and antennal insertions with elevated arcuate carinae. Posterolateral corners of head smooth and shining. Head venter mostly smooth and shining, weak sculpture present medially. Antennal scrobe smooth and shining. Clypeus mostly smooth and shining; anterior margin with short carinae laterally, median carinae absent. Pronotum mostly smooth and shining, rugoreticulate posteriorly. 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 and ventrally, anterior and posterior faces smooth and shining. Postpetiole with anterior face transversely rugulose, dorsum and posterior face smooth and shining. First tergite of gaster longitudinally costulate basally, sculpture immediately posterior to postpetiole shorter than length of postpetiole. First sternite of gaster sculptured basally. Body reddish-brown with lighter appendages.

Diagnosis, distribution and biology. Pheidole colaensis is most readily distinguished from other P. roosevelti-group species by its shiny integument and reduced sculpture. Pheidole colaensis is the only species in which the posterolateral lobes of the major caste are entirely free of sculpture. While the minor workers of the Vanua Levu species P. pegasus and P. uncagena also lack facial sculpturing above eye level, the propodeal spines of P. colaensis bear a distinctly shorter dorsal edge. Although Mann (1921) uses the presence of the median ocellus to distinguish P. colaensis from P. roosevelti , a review of material subsequently collected proves the character to be relatively variable. While all majors of P. colaensis examined by the author bear a prominent, well-developed median ocellus, the feature ranges from completely absent to poorly developed in the examined majors of P. roosevelti , often varying even within nest series. An even greater range of variability is seen within the type series of P. pegasus .

While P. colaensis appears to be restricted to the few high elevation ranges of Viti Levu, the species is locally abundant where it occurs. Pheidole colaensis is widely sympatric with P. roosevelti , with the former tending to occupy the higher elevations (800m - 1,300m) and the latter preferring a slightly lower range (300m - 1,000m). Although P. colaensis majors are scarce and timid, the minors can be observed foraging about the leaf litter some distance from their nests. The nest entrance of P. colaensis typically consists of a single turret built of small soil pellets that rises 3-5cm above the ground, and leads to chambers over one meter deep that contain many hundreds or thousands of workers. The multiple dealate queens recovered from nest excavations suggest that the species might be polygynous. The queens of P. colaensis , like those of P. bula and P. furcata , are small with reduced mesosomas.

Additional material examined. FIJI. Viti Levu: Koroyanitu National Heritage Park Mt. Batilamu near summit 3.2km SE Abaca Village , 24.viii.2006, 1125m, -17.56944°, 177.97000°, high elevation wet forest, from turret nest in bare soil, (E. M. Sarnat), EMS#2332, 3 majors (CASENT0174017, CASENT0174020, CASENT0174023), 6 minors (CASENT0174018 - CASENT0174022, CASENT0174024, CASENT0174025) ; Monasavu Rd. 1.75km SE Waimoque Settlement , 28.viii.2006, 850m, -17.67035°, 177.99375°, from turret nest in bare soil, (E. M. Sarnat), EMS#2365, 2 dealate queens (CASENT0174041, CASENT0174044), 7 majors (CASENT0174042, CASENT0174045, CASENT0174047, CASENT0174050, CASENT0174051, CASENT0174053, CASENT0174055), 7 minors (CASENT0174043, CASENT0174046, CASENT0174048, CASENT0174049, CASENT0174052, CASENT0174054, CASENT0174056) ; 7km S Monasavu Dam near powerstation headquarters , 2.ii.2005, 800m, -17.81018°, 178.03773°, from sifted leaf litter, (E. M. Sarnat), EMS#1806, 3 minors (CASENT0174036 - CASENT0174038); 7km S Monasavu Dam near powerstation headquarters , 2.ii.2005, 800m, -17.81018°, 178.03773°, from sifted leaf litter, (E. M. Sarnat), EMS#1808, 1 minor (CASENT0174039); Mt. Tomanivi 8 km ESE Navai Village , 3.ii.2005, 1023m, - 17.62415°, 178.00558°, mid-elevation rainforest, foraging, (E. M. Sarnat), EMS#1823, 4 majors (CASENT0171103, CASENT0174026 - CASENT0174028), 5 majors (CASENT0171020, CASENT0174029, CASENT0174057 - CASENT0174059) ; 3 km E Navai Village trail to Mt. Tomanivi, 1.ii.2005, 1105m, -17.51850°, 178.00680°, mid-elevation rainforest, from turret nest in bare soil, (E. M. Sarnat), EMS#1784, 3 minors (CASENT0174030 - CASENT0174032); 3.2 km E Navai Village , trail to Mt. Tomanivi, 1.ii.2005, 1294m, -17.61583°, 178.01683°, moss forest, ground foraging, (E. M. Sarnat), EMS#1785, 3 minors (CASENT0174033 - CASENT0174035).