Pheidole rugithorax, Eguchi, 2008

Eguchi, Katsuyuki, 2008, A revision of Northern Vietnamese species of the ant genus Pheidole (Insecta: Hymenoptera: Formicidae: Myrmicinae), Zootaxa 1902 (1), pp. 1-118 : 84-87

Pheidole rugithorax sp.n.

Figs. 23a–g

Pheidole sp. eg-141. Eguchi, 2003: 338 (description of male genitalia).

Type material examined: Holotype: major, Pha Lai (near forestry station), Pu Mat N.P., Nghe An, N. Vietnam [K. Eguchi leg., colony: Eg26iii06-09] ( IEBR); paratypes: 13 majors, 15 minors & 1 queen from the same colony as holotype ( IEBR, MCZC, MHNG & ACEG).

Other material examined: S. Vietnam: Dong Nai: S. Cat Tien N.P., <160 m alt. [Eg04-VN-694] . Thailand: Chiang Mai: Doi Suthep-Pui N.P., ca. 900 m alt. [Eg01-TH-084] ; Kanchanaburi: Srinakarin Dam N.P., 150–200 m alt. [TH02-SKY-11] ; Chanthaburi: Khao Soi Dao [Eg01-TH-052]. Myanmar: Cat & Kitten Island [Ecoswiss 28/ii/1999]. Eguchi’s informal species code “ Pheidole sp. eg-141” applies to this species .

Worker measurements: Holotype (major). —HL 1.21 mm; HW 1.18 mm; CI 98; SL 0.72 mm; SI 61; FL 0.91 mm; FI 77.

Nontype major (n=4). — HL 1.01–1.21 mm; HW 0.96–1.18 mm; CI 95–99; SL 0.64–0.72 mm; SI 61–69; FL 0.77–0.91 mm; FI 77–85.

Minor (n=5, including one paratype minor, for HL, HW, CI, SL, SI; n=4 including one paratype minor, for FL, FI). — HL 0.55–0.67 mm; HW 0.49–0.59 mm; CI 86–89; SL 0.64–0.76 mm; SI 123–137; FL 0.66–0.81 mm; FI 135–145.

Worker description

Major. — Head in lateral view not impressed on vertex; dorsum of head sparsely bearing long standing hairs which are unclearly distinguished from shorter and thinner background hairs; frons rugose longitudinally; vertex reticulate or rugoso-reticulate; dorsal and dorsolateral faces of vertexal lobe reticulate; frontal carina conspicuous; antennal scrobe inconspicous or very shallow; median longitudial carina of clypeus absent, or present but weak; median and submedian processes of hypostoma absent or inconspicuous; lateral processes developed well, located rather ventrally; antenna with a 3-segmented club; maximal diameter of eye almost as long as, or a little longer than antennal segment X. Promesonotal dome in dorsal view reticulate, or transversely rugose or rugoso-reticulate, in lateral view with a low or inconspicouous mound on its posterior slope; humerus of the dome not or hardly produced; the dome at the humeri narrower than at the bottom; petiole almost as long as, or a little longer than postpetiole (excluding helcium). Petiolar node in lateral view subangulate dorsally; postpetiole massive. First gastral tergite smooth and shining entirely.

Minor. — Frons smooth to shagreened; vertex smooth, shagreened or sculptured (rugoso-reticulate or rugoso-punctate); dorsolateral face of head behind eye rugoso-reticulate or rugoso-punctate at least weakly; preoccipital carina conspicuous to weak dorsally and aterally; median part of clypeus smooth and shining, without a median longitudinal carina; 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 than antennal segment X. Promesonotal dome in lateral view usually flattend dorsally (but rarely convex as in the minor of colony Eg01-TH-084), with a low or inconspicuous mound on its posterior slope; dorsum of the dome rugoso-reticulate, or smooth to shagreened but sparsely sculptured with rugulae; lateral face of the dome rugoso-reticulate or rugoso-punctate at least weakly; humeral area of the dome marked with rugulae, and often forming a low prominence; mesopleuron, metapleuron and lateral face of propodeum punctured or rugoso-punctate weakly, or largely smooth. Petiole as long as or shorter than postpetiole (excluding helcium); postpetiole massive.

Recognition: In Southeast Asia I have recognized two Pheidole species (P. sp. eg-141 and P. sp. eg-174) which, in the major worker, much resemble each other and are also very similar to P. protea . Practically these three are hard to separate in the major (and so Eguchi (2004) determined P. sp. eg-141 as P. protea ). However, P. sp. eg-141 and P. sp. eg-174 are separable from each other by the characteristics of the minor. In the minor of P. sp. eg-141 the promesonotal dome is sculptured by rugulae at least laterally, and its humeral area is strongly maked with rugulae and often armed with a low humeral prominence. On the other hand, in the minor of P. sp. eg-174, the dome is almost smooth and shining, and its humeral area is neither marked with rugulae nor armed with a humeral prominence. Since P. protea was described solely based on the major, the assignment of either of P. sp. eg-141 or P. sp. eg-174 to P. protea would be impossible until decisive characters useful in separating these three in the major are found. In this situation it seems unreasonable to leave P. sp. eg- 141 and P. sp. eg-174 unnamed. Here I describe P. sp. eg-141 and P. sp. eg-174 as new species ( Pheidole rugithorax sp.n. and P. laevithorax sp.n., respectively).

Figures

FIGURE 23a–d, Pheidole rugithorax sp.n., holotype (major) [Eg26iii06-09] — a, head in full-face view; b, head in lateral view; c, mesosoma and waist in dorsal view; d, mesosoma and waist in lateral view.