Pheidole planifrons Santschi

Eguchi, K., 2008, A revision of Northern Vietnamese species of the ant genus Pheidole (Insecta: Hymenoptera: Formicidae: Myrmicinae)., Zootaxa 1902, pp. 1-118 : 77-80

Pheidole planifrons Santschi

Figs. 21a-g

Pheidole planifrons Santschi , 1920: 166. Eguchi, Bui et al. 2005: 90 (checklist). Syntypes: 2 majors & 3 minors, "Indochine Dalat (Bouvard)" [Dalat, Lam Dong, S. Vietnam], NHMB, examined.

Pheidole sp. eg-75 (? planifrons Santschi ). Eguchi 2003: 337-338 (description of male genitalia).

Other material examined: Vietnam: Vinh Phuc: Tam Dao, <900 m alt. [Eg99-VN-073]; Bac Giang: W. Yen Tu N.P. (= Tay Yen Tu N.P.), 21°10-11'N, 106°43-44'E, 190 m alt. [Eg03-VN-015]; Nghe An: Pu Mat N.P. (Pha Lai Area) [Eg25iii06-12]; Dong Nai: S. Cat Tien N.P., <160 m alt. [Eg04-VN-500, -555, -566, - 626, -679]. Thailand: Chiang Mai: Doi Suthep-Pui, 800-900 m alt. [Eg01-TH-095, -097, -103, -107, -109], Doi Chiang Dao [Eg01-TH-127, -129, -133, -150, -153]; Nakhonratchashima: nr. Sakaerat Environmental Research Centre [Eg01-TH-504, -512, -548]; Trang: Khao Chong Waterfall [Eg01-TH-670, -693, -695, -701]; Songkhla: Ton Nga Chang, nr. Hat Yai [Eg01-TH-625]; Narathiwat: Bala area of Bala-Hala W.S. [Eg01-TH- 630]. Indonesia: W. Java: Kebun Raya, Bogor [FI90-21, FI95-736], Cidaon, Ujung Kulon N.P. [FI97-125, - 135].

Worker measurements & indices: Major (n=5). - HL 2.01-2.11 mm; HW 1.75-1.85 mm; CI 86-88; SL 0.84-0.92 mm; SI 45-51; FL 1.38-1.44 mm; FI 75-81.

Minor (n=5). - HL 0.65-0.71 mm; HW 0.54-0.57 mm; CI 80-83; SL 0.83-0.87 mm; SI 153-155; FL 0.90-0.98 mm; FI 167-172.

Worker description

Major. - Head in lateral view with vertex which forms a gentle (and often weakly impressed) slope toward vertexal lobe; frons flat, densely rugose longitudinally, with sparse and very short appressed hairs, but without standing hairs except on the marginal area; vertex and dorsal and lateral faces of vertexal lobe reticulate or rugoso-reticulate, with standing hairs; frontal carina well developed horizontally, partly overhanging antennal scrobe; clypeus without median longitudinal carina; hypostoma without median and submedian processes, but with relatively small or low lateral processes; outer surface of mandible (excluding area around the base) smooth, with sparse and very short appressed hairs; antenna with a 3-segmented club; maximal diameter of eye longer than or almost as long as antennal segment X. Promesonotal dome in dorsal view rugose or rugoso-reticulate transversely, with interspaces/enclosures smooth or weakly punctured; the dome in lateral view with a conspicuous prominence or mound on its posterior slope; humerus very weakly produced laterad; the dome at the humeri as broad as or narrower than at the bottom. Petiole (a little) longer than postpetiole (excluding helcium); petiolar node in rear view weakly to strongly concave mediodorsally; postpetiole not massive. First gastral tergite longitudinally rugoso-punctate entirely (but its posteromedian part often polished).

Minor. - Dorsum of head with sparse thick standing hairs; frons and vertex smooth or shagreened; preoccipital carina conspicuous dorsally and laterally; median part of clypeus smooth and shining; median longitudinal carina of clypeus absent, or present but very weak; antenna with a 3-segmented club; scape extending far beyond posterolateral margin of head; maximal diameter of eye shorter than antennal segment X. Dorsum of mesosoma with sparse thick and short standing hairs which are somewhat stubbed apically; promesonotal dome largely smooth and shining, in lateral view with a low mound on its posterior slope; humerus in dorso-oblique view not produced; mesopleuron, metapleuron and lateral face of propodeum well punctured. Petiole as long as or a little longer than postpetiole (excluding helcium); postpetiole relatively large.

Recognition: This species is well characterized among Indo-Chinese species by the combination of the following features: in the major frontal carina well developed horizontally, partly overhanging antennal scrobe; in the major gena much more than 1.5 times as long as maximal diameter of eye; in the minor frons and vertex smooth or shagreened; in the minor preoccipital carina conspicuous dorsally and laterally; in the major hypostoma without median and submedian processes; in the major and minor posterior slope of promesonotal dome with a mound; in the minor dorsum of mesosoma sparsely with thick and short standing hairs which is somewhat stubbed apically; in the major first gastral tergite longitudinally rugoso-punctate entirely or largely.

This species is similar to P. yeensis Forel . In the major of the latter, however, vertex in lateral view is strongly impressed in front of vertexal lobe; and frons is sparsely sculptured with longitudinal rugulae. The majors of this species and P. capellinii are similar to each other, but morphology of the minor is very different between the two (see under P. capellinii ).

Distribution & bionomics: Known from N. Vietnam, S. Vietnam, Thailand and Java. This species occurs from forest edges to rather woody habitats, and nests in the soil and rarely in the walls of termite mounds on the ground.