Pheidole elongicephala Eguchi, 2008

Eguchi, K., 2008, A revision of Northern Vietnamese species of the ant genus Pheidole (Insecta: Hymenoptera: Formicidae: Myrmicinae)., Zootaxa 1902, pp. 1-118 : 20-21

Pheidole elongicephala Eguchi sp.n. Figs. 4a-h

Pheidole sp. B (aff. aglae Forel ). Yamane et. al. 2003: 58 (checklist).

Pheidole aglae Forel . Misidentification made by Eguchi et al. 2004 (ecological study).

Type material examined: Holotype, major, Cuc Phuong N.P. ("Dong Nguoi Xua" Area), Ninh Binh, N. Vietnam [Eg09vi05-08 (K. Eguchi leg., 09/JUN/2005)] (IEBR); paratypes: 7 majors, 9 minors & 2 males, same data as holotype (IEBR, MHNG, MCZC, & ACKE).

Other material examined: S. China: Hong Kong: Taipo Kau N.P., New Territory [Eg00-HK-028]. Vietnam: Thai Nguyen: My Yen Commune Forest, 21°35'N, 105°36'E, Na Hau Village [Eg01-VN-158]; Bac Giang: W. Yen Tu N.P. (=Tay Yen Tu N.P.), 21°10-11'N, 106°43-44'E, 190-370 m alt. [Eg03-VN-030, -040, -135, -153, -160; B&E03-12]; Ha Tay (mislabeled as Ha Tai): Ba Vi N.P., 21°03'N, 105°22'E, 400-700 m alt. [Eg02-VN-009, -022]; Ninh Binh: Cuc Phuong N.P. [Eg11iv05-14; Eg15vi05-07]. Part of specimens to which Eguchi's informal species code " Pheidole sp. eg-101" has been applied (Eguchi, Bui et al. 2005: 90) is P. elongicephala , and the remainder is P. ochracea .

Worker measurements & indices: Holotype (major). - HL 1.76 mm; HW 1.56 mm; CI 89; SL 1.18 mm; SI 76; FL 1.56 mm; FI 100.

Nontype major (n=4). - HL1.68-1.78 mm; HW 1.51-1.57 mm; CI 88-90; SL 1.13-1.16 mm; SI 74-75; FL 1.53-1.56 mm; FI 99-102.

Minor (n=5, including one paratype minor). - HL 0.78-0.85 mm; HW 0.58-0.64 mm; CI 75-76; SL 1.06-1.19 mm; SI 176-187; FL 1.11-1.25 mm; FI 187-197.

Worker description

Major. - Body deep yellowish-brown, brown or deep reddish-brown, with paler appendages. Head in lateral view not or weakly impressed on vertex; vertexal lobes in full-face view relatively close to each other; frons and anterior part of vertex longitudinally rugose; posterior part of vertex and dorsum of vertexal lobe rugoso-reticulate or reticulate; clypeus without a conspicuous median longitudinal carina; frontal carina conspicuous; antennal scrobe very shallow; hypostoma with a very low or inconspicuous median process and a pair of low or inconspicuous submedian processes in addition to a pair of conspicuous lateral processes; antenna with a 3-segmented club; maximal diameter of eye shorter than antennal segment X. Promesonotal dome sparsely rugose transversely, with interspaces smooth and shining; a conspicuous prominence present on its posterior slope; humerus not or hardly produced laterad; the dome at the humeri much narrower than at the bottom; mesopleuron and metapleuron weakly punctured, overlain by rugoso-reticulation; propodeal spine narrowly based. Petiole longer than postpetiole (excluding helcium); postpetiole not massive. First gastral tergite smooth entirely, or shagreened only around its articulation with postpetiole.

Minor. - Body yellowish-brown or brown, with paler appendages. Head in full-face view elongate-elliptical, tapered posterad behind eyes; frons and vertex smooth or shagreened; median portion of clypeus smooth; median longitudinal carina very weak or absent; occipital carina forming a well-developed collar; antenna with a 3-segmented club; scape extending far beyond posterolateral margin of head; maximal diameter of eye much shorter than antennal segment X; 8-9 ommatidia present on the long axis of eye; promesonotal dome smooth and shining, in lateral view with a low mound on its gentle posterior slope; the mound bearing usually 4 standing hairs; humerus in dorso-oblique view not raised/produced; mesopleuron, metapleuron and lateral face of propodeum punctured, often overlain by weak rugulae; propodeal spine elongate-triangular, directing upward; petiole (a little) longer than postpetiole (excluding helcium); postpetiole not massive.

Recognition: Pheidole elongicephala, P. binghamii and P. ochracea sp.n. are morphologically very similar to each other (and probably very closely related to each other). Differences between P. elongicephala and P. binghamii are as follows: head behind eyes in full-face view more elongated and tapered posterad in the minor of the former than in that of the latter; mound on the posterior slope of promesonotal dome bearing usually4 standing hairs in the minor of the former, but usually only a pair of standing hairs in the minor of the latter. The body size of both the subcastes is almost constantly larger in P. elongicephala than in P. binghamii . The two species are allopatric or parapatric (range of P. binghamii : Myanmar, Thailand, S. Vietnam). Differences between P. elongicephala and P. ochracea sp.n. are as follows: head behind eyes in full-face view more elongated and tapered posterad in the minor of the former than in that of the latter; occipital carina of the minor much more developed in the former than in the latter; the long axis of eye having 8-9 ommatidia in the minor of the former, but 6-7 ommatidia in that of the latter. They are sympatric in S. China and N. Vietnam.

Distribution & bionomics: Known from N. Vietnam and S. China. This species occurs in woody habitats, and nests in rotting wood material (logs, stubs) and in the soil.