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 premesonotal 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.