Pheidole aspidata

The type colony was found nesting under a stone in a rainforest. Both queen and soldier castes have a truncate head, which for Pheidole is unique.

Identification
Eguchi and Bui (2005) - The front of head truncated (major); in dorsolateral view genal corner extended as a triangular process (major); median part of hypostoma with a pair of large and a low processes (major): posterior declivity of promesonotal dome at most with an inconspicuous prominence (major and minor): promesonotal dome smooth and shining (minor) or smooth and shining with several transverse rugulae (major).

This species is unique among Oriental species of the genus in having the diagnostic characteristics mentioned above. The major of Pheidole sayapensis (Borneo) and Pheidole capellinii (Indo-Chinese and Indo-Malayan subregions) have the front of head somewhat truncated. In P. sayapensis, however, the major lacks a genal corner extended as a triangular process and has a single stout median process on hypostoma; and the minor has its head and mesosoma coarsely and strongly reticulate. In P. capellinii the major also lacks a genal corner extended as a triangular process; both the major and minor have a prominence on the posterior declivity of promesonotal dome: and the minor has head and mesosoma weakly punctured and dull.

Distribution based on Regional Taxon Lists
Oriental Region: Vietnam.

Nomenclature

 *  aspidata. Pheidole aspidata Eguchi & Bui, 2005: 723, figs. 1-12 (s.w.q.) VIETNAM.

Worker
Major TL 2.4-2.8 mm, HL 1.18-1.23 mm. HW 1.13-1.20 mm, SL 0.53-0.56 mm. FL 0.74-0.78 mm, Cl 95-98, SI 46-50. FI 65-68 (N=5); body brown; head in full-face view very weakly convex laterad, shallowly and broadly concave posteriorly, in profile highly raised at the border of frons and vertex, without any impression on vertex; vertex and vertexallobe covered by standing hairs: anterior part of vertex rugosareticulate; posterior part of vertex and dorsum of vertexal lobe weakly punctured and dull, overlain by weak reticulation; the front of head truncated; frons longitudinally rugose, bearing appressed hairs: median part of frons impressed, surrounded anterolaterally by gentle slopes toward frontal carinae and posteriorly by a crescent ridge of frons: genal comer extended as a triangular process; fronto-clypeal suture very weak to evanescent: median part of clypeus smooth; median longitudinal carina of clypeus absent or at most evanescent: frontal carina well developed, partly overhanging antennal scrobe; hypostoma with a pair of large and a low processes in addition to the process just mesal to each mandibular base; lateral processes relatively well developed, but smaller than lateral ones of the three median processes; dorsal part of outer surface of mandible smooth and shining, sparsely with short appressed hairs: submarginal zone of masticatory margin with a row of longer appressed to decumbent hairs; antenna with a 3-segmented club; scape reaching the level of posterior end of frons; scape shaft flattened in its basal half, curved with an internal angle of a little more than 90 degrees around 2/5 distance from the basal rim, bearing several long hairs along anterior margin: eye small: maximal diameter of eye almost equal to the length of antennal segment X; distance between mandibular insertion and anterior margin of eye 2.3-2.6 times as long as maximal diameter of eye; promesonotal dome in profile highly raised without a conspicuous prominence on its posterior declivity, smooth and shining, dorsally with several transverse rugulae; dorsolateral part of the dome not produced laterad: mesopleuron, metapleuron and lateral face of propodeum largely punctured and dull; propodeal spine narrowly to moderately based; petiole longer than postpetiole (excluding helcium), without subpetiolar process; petiolar node in posterior view hardly concave or not concave mediodorsally; postpetiole 1.85-2.0 times as broad as petiolar node: first gastral tergite largely smooth and shining except a weakly punctured area around its articulation with postpetiole.

Minor TL 1.7- 1.9 mm, HL 0.58-0.59 mm. HW 0.52-0.54 mm, SL 0.55-0.57 mm, FL 0.59-0.60 mm, CI 90-92. SI 104-106. FI 111-113 (N=5); body yellowish brown; head smooth and shining except very weakly rugosa-punctate dorsolateral area; dorsal part of preoccipital carina weak but not evanescent: median part of clypeus smooth and shining, with a very weak or evanescent median longitudinal carina; antenna with a 3-segmented club; scape exceeding posterior margin of head by the length of second antennal segment or more; eye small, consisting of 13-18 ommatidia: eye much shorter than antennal segment X; promesonotal dome smooth and shining, in profile without a conspicuous prominence on its posterior declivity; mesopleuron. metapleuron and latera l face of propodeum largely punctured and dull; propodeal spine small and slender, narrowly based; petiole longer than postpetiole (excluding helcium): postpetiole somewhat massive, 2.0-2.3 times as broad as petiolar node: gaster smooth and shining.

Queen
(alate teneral queens) Tl 4.0-4.1 mm, HL 1.04-1.08 mm, HW 1.09-1.11 mm, SL 0.59-0.60 mm, FL 0.84-0.86 mm. CI 103-105, SI 54, FI 77-78 (N=4 for TL, HL, HW, SL, CI and SI: N=2 for FL and FI); general shape of head like that of the major; but vertexal lobe and genal corner less developed than those of the major: ocelli small but conspicuous; clypeus, frontal carina, hypostomal processes and mandible as seen in the major: antenna with 3-segmented club; scape a little exceeding the level of median ocellus; the shape of scape shaft as seen in the major; eye large; distance between mandibular insertion and anterior margin of eye 0.85-0.9 times as lo ng as maximal diameter of eye; mesosoma robust. ca. 0.9 times as broad as head: pronotum overhung by rnesoscutum; mesonotum in profile forming a flattened dorsal surface; submedial area of mesosculum rugose: parapsidal furrow very weak; mesoscutellum almost completely overhanging metanotum, smooth and shining dorsally: propodeal spine broadly based; forewing venation type IIb of Ogata (1991): radial cell open: petiole longer than postpetiole (excluding helcium), without subpetiolar process; petiolar node in posterior view hardly concave or not concave rnediodorsally: postpetiole 1.9-2.0 times as broad as petiolar node: first gastral tergite largely smooth and shining except punctured and dull area around articulation with postpestiole.

Type Material
Holotype: major from colony Eg04-VN-800: type locality: SCat Tien N. P. (<ca. 160m alt.). Dong Nai ProVince. Vielnam (Fig. 12): depository: IEBR Paratypes: 30 majors, 35 minors and 5 alate queens from the same colony to which the holotype belongs, depository:, , , , ,.

References based on Global Ant Biodiversity Informatics

 * Zryanin V. A. 2011. An eco-faunistic review of ants (Hymenoptera: Formicidae). In: Structure and functions of soil communities of a monsoon tropical forest (Cat Tien National Park, southern Vietnam) / A.V. Tiunov (Editor). – M.: KMK Scientific Press. 2011. 277 р.101-124.