Pheidole uncagena Sarnat

Sarnat, Eli M., 2008, A taxonomic revision of the Pheidole roosevelti - group (Hymenoptera: Formicidae) in Fiji, Zootaxa 1767, pp. 1-36 : 28-31

Pheidole uncagena Sarnat sp. n.

Figs. 50–52 , 71–73

Paratypes. From same nest series as holotype: 4 majors (CASENT0174276, CASENT0174277, CASENT0174279, CASENT0174280), 3 minors (CASENT0171026, CASENT0174278, CASENT0174281), (FNIC, NMNH, ANIC); additional specimens in alcohol (NMNH).

MAJOR. TL 6.62–7.21, HL 2.17–2.26, 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 with sides not distinctly broader behind eyes than in front of eyes. Median ocellus absent in all specimens examined. Mesonotal process, in profile, produced as a thick, upturned lamellate plate overhanging propodeum; in dorsal view attachment to mesonotum attenuated, posterior margin and anterolateral margins 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 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 where they become weaker and discontinuous; intercarinular spaces smooth and shining to lightly foveolate. Eye surrounded by elevated carinae. Antennal scrobe smooth and shining. Clypeus mostly smooth and shining with several weak carinae extending from frontal lobes that terminate before reaching anterior margin; median carina weak to absent. Posterolateral portion of posterolateral lobes mostly longitudinally striate. Head venter rugose. Promesonotum transversely rugose. Anepisternum rugose. Katepisternum mostly smooth and shining with several rugae. Petiole with apical face smooth; posterior face laterally and ventrally rugose. Postpetiole anterior and posterior face with dense transverse striae; dorsum with transverse carinae. Gaster costulate on basal quarter of first segment; sternite of first segment striate laterally; elsewhere smooth and shining. Body reddish-brown with lighter appendages.

MINOR. TL 3.47–4.21, HL 0.75–0.89, HW 0.67–0.82, CI 0.88–0.93, FL 1. -1.34, FI 1.50–1.58, SL 1.08– 1.21, SI 1.31–1.45, AE 0.23–0.30, DE 0.22–0.31, PSI 0.87–1.13 (8 measured).

Head, in full face view, ovate, sides strongly convex and joining together evenly to form the posterior margin; in profile, posterior margin weakly dorsoventrally pinched where dorsum and venter join at an obtuse angle. Genal carinae strongly elevated into ventrolateral flanges with a long gently sloped posterior edge and a short steeply sloped anterior edge. Clypeus with anterior margin convex laterally, flat to weakly concave medially. Frontal carinae weak and terminating near eye level. Mesonotal process produced as a thin plate; in dorsal view, attachment to mesonotum strongly attenuated giving the sides a concave appearance, posterior margin moderately to strongly excised. 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 equal to length of anterior edge.

Head smooth and shining on all surfaces expect for arcuate carinae between eyes and antennal insertions. Clypeus occasionally with a few weak carinae attached to anterior border. Promesonotum, in dorsal view smooth and shining with a few very weak transverse impressions. Anepisternum rugose. Katepisternum smooth and shining. Metapleuron rugose. Head and mesosoma reddish-brown; waist, gaster and legs paler.

Etymology. The specific epithet uncagena is a noun in apposition combining the Latin uncus, meaning hook, and gena, meaning cheek, in reference to the modification of the genal carina into a hook-like flange in this species.

Diagnosis, distribution and biology. Pheidole uncagena is most easily confused with P. pegasus . Both are sympatric on Vanua Levu , and are characterized by a smooth and shining integument, paler coloration, and long propodeal spines. The features that best separates P. uncagena , not only from P. pegasus but from all other P. roosevelti -group species, are the modified genal carina that appear almost hook-like in oblique lateral view, and the strongly attenuated mesonotal process, which is best seen in dorsal view.

Some variation exists between the Vanua Levu type series and the minor workers collected in malaise traps from Taveuni. The propodeal spines of the type series are bifurcate, with a distinct anterior point in addition to the posterior point, whereas the anterior point of the Taveuni specimens are reduced to blunt angle, and the posterior points are longer than those exhibited by the Vanua Levu specimens. Additionally, the genal carinae of the type series come to a more definite point, whereas those of the Taveuni specimens are more blunt.

Although no queen of P. uncagena has been collected, the similarities it shares with P. p e g a s u s predict that it will be a large queen with a well-developed mesonotum. The type series was taken from a nest in bare soil with multiple turret entrances. The recovery of this species from malaise traps suggest that the workers at least, occasionally, forage in the arboreal stratum.

Additional material examined. FIJI. Taveuni: 5.6 km SE Tavuki Village [Mt. Devo], 3.i–10.i.2003, 1187m, -16.84300°, 179.95500°, primary rainforest, malaise, (E. Schlinger, M. Tokota’a), FJTA 8a_M01_12, 3 minors (CASENT0174282 – CASENT0174284); Devo Peak Radio Tower, 13.xii–20.xii.2002, 1200m, - 16.85000°, 179.96667°, rainforest, malaise, (M. Irwin, E. Schlinger, M. Tokota’a), 1 minor (CASENT0174285).

Two specimens, both minor workers, are labeled with the following locality: Vanua Levu : 6 km NW Kilaka Village Batiqere Range, 3.i. 2003, 113m, -16.73170°, 178.99970°, malaise, (E. Schlinger, M. Tokota’a), FJVN 58c_M02_06, (CASENT0174286, CASENT0174287). The record, if correct, would make this the lowest elevation occurrence of any P. roosevelti -group species. Remarkable, in itself, suspicion of erroneous data is further compounded by the observation that all other known records of the species are taken from the tallest peaks of Vanua Levu and Taveuni. It is with caution that the locality data is recorded here, and I refrain from including it in the presented figures.

Figures

FIGURES 32 – 52. Minor workers. 32 – 34. Pheidole bula, paratype; 35 – 37. P. colaensis; 38 – 40. P. f u rc a t a, paratype; 41 – 43. P. p e g a s u s, paratype; 44 – 46. P. roosevelti; 47 – 49. P. simplispinosa, paratype; 50 – 52. P. uncagena, paratype.

FIGURES 53 – 73. Major workers. 53 – 55. Pheidole bula, holotype; 56 – 58. P. colaensis; 59 – 61. P. furcata, holotype; 62 – 64. P. p e g a s u s, holotype; 65 – 67. P. roosevelti; 68 – 70. P. simplispinosa, holotype; 71 – 73. P. uncagena, holotype.