Pheidole indosinensis Wheeler, 2008

Eguchi, K., 2008, A revision of Northern Vietnamese species of the ant genus Pheidole (Insecta: Hymenoptera: Formicidae: Myrmicinae)., Zootaxa 1902, pp. 1-118 : 43-46

Pheidole indosinensis Wheeler stat.n.

Figs. 11a-h

Pheidole sulcaticeps subsp. indosinensis Wheeler , 1928: 10. Eguchi, Bui et al. 2005: 90 (checklist). Syntypes: 6 minors, "Yi Liang, Indochina, F. Silvestri leg." [China], MCZC cotype-20665, examined.

Other material examined: S. China: Guangdong: Dawuling N.R., Maoming [J. Fellowes], Nankunshan N.R., Top Gate, Longmen [J. Fellowes]; Hainan: Diaoluoshan N.R., Lingshui [J. Fellowes], Jianfengling N.R., Ledong [J. Fellowes]. N. Vietnam: Vinh Phuc: Tam Dao N.P., 21°27'N, 105°38'E, ca. 900 m alt. [Eg01- VN-108, -110, -111], Tam Dao N.P., 900-1100 m alt. [Eg99-VN-054, -057]; Ha Tay (misspelled as "Ha Tai"): Ba Vi N.P., 21°03'N, 105°22'E, ca. 1100 m alt. [Eg02-VN-032, -034], Ba Vi N.P., 1100-1200 m alt. [Eg99- VN-128].

Worker measurements & indices: Major (n=5). - HL 1.65-1.80 mm; HW 1.58-1.78 mm; CI 94-99; SL 0.91-0.99 mm; SI 55-59; FL 1.27-1.36 mm; FI 76-84.

Minor (n=5). - HL 0.70-0.78 mm; HW 0.59-0.67 mm; CI 83-86; SL 0.87-0.96 mm; SI 143-149; FL 0.89-1.00 mm; FI 149-157.

Worker description

Major. - Body deep yellowish-brown with paler appendages. Head in lateral view not or hardly impressed on vertex; vertexal lobes in full-face view relatively widely separated from each other; frons and anterior part of vertex rugose longitudinally-obliquely; posterior part of vertex and dorsal and dorsolateral faces of vertexal lobe rugoso-reticulate or reticulate; median longitudinal carina of clypeus usually conspicuous but sometimes very weak or inconspicuous; frontal carina relatively well developed; antennal scrobe present as a shallow impression; median process of hypostoma poorly developed or almost absent; submedian processes developed well; lateral processes conspicuous; antenna with a 3-segmented club; maximal diameter of eye shorter than or almost as long as antennal segment X (sometimes a little longer than antennal segment X). Promesonotal dome in dorsal view sparsely rugose or rugoso-reticulate transversely, with interspaces smooth, in lateral view with a low prominence/mound on its posterior slope; humerus hardly or very weakly produced laterad; the dome at the humeri as broad as or narrower than at the bottom. Petiole longer than postpetiole(excluding helcium); postpetiole not massive. First gasteral tergite smooth over the surface or very weakly punctured in its anterior 1/3.

Minor. - Body yellowish-brown. Frons and vertex smooth and shining or shagreened, or sometimes weakly rugoso-reticulate; dorsolateral and lateral face of head usually rugoso-reticulate dimly or weakly; median portion of clypeus smooth and shining, with a weak or conspicuous median longitudinal carina; preoccipital carina conspicuous dorsally and laterally; antenna with a 3-segmented club; scape extending far beyond posterolateral margin of head; maximal diameter of eye shorter than antennal segment X. Promesonotal dome largely smooth and shining, in lateral view usually with an inconspicuous mound on its gentle posterior slope; humerus in dorso-oblique view usually (but not always) produced very weakly; mesopleuron, metapleuron and lateral face of propodeum weakly punctured; propodeal spine elongate-triangular. Petiole longer than postpetiole (excluding helcium); postpetiole not massive.

Recognition: I was unable to find the type material of the nominotypical taxon of Pheidole sulcaticeps Roger in a possible depository (Zoologisches Museum an der Humboldt-Universitat zu Berlin). According to its original description (Roger, 1863a: 193-194) head of the major is in lateral view strongly impressed at the posterior 1/3 of its dorsum, and dorsum of "mesonotum [= a mound (prominence) on the posterior slope of promesonotal dome]" of the minor is in lateral view horizontal at the begining. These characteristics are not seen in P. sulcaticeps subsp. indosinensis which I recognised based on my examination of the type material of the subspecies. Thus, I here conclude that the two forms are different from each other at the species level, and raise the subspecies indosinensis to the species rank.

This species is characterized among Indo-Chinese species by a combination of the following characteristics: in the major dorsal and lateral faces of vertexal lobe rugoso-reticulate or reticulate; in the major frontal carina relatively well developed; in the minor preoccipital carina conspicuous dorsally and laterally; in the major submedian processes of hypostoma well developed; in the major posterior slope of promesonotal dome with a low prominence/mound; in the major and minor petiole longer than postpetiole. This species is similar to Pheidole elongicephala sp.n. and P. ochracea sp.n. However, in the major of the latter two vertexal lobes in full-face view relatively close to each other; and submedian processes of hypostoma is usually (but not always) very small or inconspicuous.

Distribution & bionomics: Known from N. Vietnam and S. China. This species seemingly prefers woody habitats. Majors serve as repletes [Eg99-VN-128].