Pheidole dugasi Forel

Eguchi, K., 2008, A revision of Northern Vietnamese species of the ant genus Pheidole (Insecta: Hymenoptera: Formicidae: Myrmicinae)., Zootaxa 1902, pp. 1-118 : 17-20

Pheidole dugasi Forel

Figs. 3a-g, 32a, b

Pheidole dugasi Forel , 1911c: 222-223. Yamane et al. 2003 (checklist), Eguchi, Bui et al. 2005: 89 (checklist). Syntypes: 3 minors, "Cochinchine (Dugas)" [S. Vietnam], MHNG, examined, one of them designated here as the lectotype [Fig. 32a, 32b].

Pheidole sp. eg-59 (.. ocellata Zhou ). Eguchi 2003: 337 (description of male genitalia).

Other material examined: S. China: Guangxi: Shiwandashan N.R., Quinzhou [J. Fellowes]; Hainan: Wuzhishan N.R., Qiongzhong, 700 m alt. [J. Fellowes], Wangxia N.R., nr. Bawangling, Changjiang [J. Fellowes], Jianling N.R., Wanling [J. Fellowes]. N. Vietnam: Ha Tay (mislabeled as Ha Tai): Ba Vi N.P., 21°03'N, 105°22'E, ca. 400 m alt. [K. Eguchi]; Ninh Binh: Cuc Phuong N.P., 20°14'N, 105°36'E [VN98- SKY-23; Eg01-VN-200, -201; Eg10vi05-01]. S. Vietnam: Dong Nai: S. Cat Tien N.P., <160 m alt. [Eg04- VN-508, -539]. Thailand: Chiang Mai: Campus of Chiang Mai Univ. [Eg01-TH-162], Doi Chiang Dao [Eg01- TH-142], Doi Chiang Dao, 500-600 m alt. [Sk. Yamane]; Chanthaburi: Khao Soi Dao W.S. [TH01-SKY-03; Eg01-TH-002, -020, -034; H. Okido]; Chacheongsao: Khao Ang Reu Nai W.S., near the Headquarters [TH03- SKY-89].

Worker measurements & indices: Major (n=5). - HL 3.38-3.60 mm; HW 3.15-3.40 mm; CI 93-99; SL 1.48-1.67 mm; SI 47-49; FL 2.35-2.49 mm; FI 71-78.

Minor (n=5). - HL 0.97-1.19 mm; HW 0.84-1.04 mm; CI 85-88; SL1.15-1.36 mm; SI 124-137; FL 1.47-1.67 mm; FI 159-175.

Worker description

Major. - Head in lateral view roundly convex dorsally, not impressed on vertex; frons with longitudinal-oblique rugulae which reach the end of vertexal lobes; frontal carina and antennal scrobe absent; clypeus with a conspicuous median longitudinal carina; hypostoma with an inconspicuous or low and broad median and low submedian processes in addition to small to conspicuous lateral processes; the median process somewhat emaginate or with a concavity in the center; antenna with a 3-segmented club; maximal diameter of eye (much) longer than antennal segment X; median ocellus often present. Promesonotal dome with a small to inconspicuous prominence or mound on its posterior slope; humerus not produced; the dome much narrower at the humeri than at the bottom. Petiole (a little) longer than postpetiole (excluding helcium); postpetiole not massive. First gastral tergite rugoso-punctate weakly but densely.

Minor. - Dorsum of head largely smooth; area between antennal insertion and eye with rugulae; dorsolateral and posterodorsal faces of head sometimes shagreened; preoccipital carina conspicuous dorsally and laterally; median part of clypeus smooth; median longitudinal carina of clypeus absent, or sometimes present but inconspicuous or weak; antenna with a 3-segmented club; scape extending far beyond posterolateral margin of head; maximal diameter of eye almost as long as, or a little shorter or a little longer than antennal segment X. Promesonotal dome smooth and shining, usually bearing very long hairs dorsally, in lateral view with a low or inconspicuous mound on its posterior slope; humerus of the dome in dorsal-oblique view not raised/ produced; mesopleuron, metapleuron and lateral face of propodeum smooth and shining, or at most very weakly punctured partly; propodeal spine in lateral view spiniform or elogate-triangular, directing upward. Petiole almost as long as postpetiole (excluding helcium); postpetiole relatively large.

Recognition: This species is characterized among Indo-Chinese species by the combination of the following characteristics: in the major and minor body extremely large; in the major frons with longitudinal-oblique rugulae which run till the end of vertexal lobes; in the major and minor antennal club 3-segmented. In N. Vietnam there are two other extremely large-sized species, Pheidole gatesi (Wheeler) and P. smythiesii Forel . But these two species are easily separated from P. dugasi by the 4-segmented antennal club in the major and minor. Pheidole magna Eguchi (see below) is relatively similar to P. dugasi , but easily separated from P. dugasi by the following characteristics of the major of P. magna : dorsal and lateral faces of vertexal lobe smooth and shining; first gastral tergite smooth and shining, often with a weakly punctured area just around its articulation with postpetiole (see also Eguchi 2006).

Distribution & bionomics: Known from Vietnam, S. China and Thailand. This species usually nests under the ground in woody gardens and forest edges. Majors serve as repletes (e.g., Eg01-TH-034, -142). In S. Cat Tien N.P. (S. Vietnam) I observed masses of workers retrieving seeds from mammal feces.