Pheidole aristotelis

This species inhabits well-developed forests from lowlands to hill areas (probably not exceeding 1000 m alt.). It nests in rotting twigs and wood blocks on the forest floor, and stores up a number of tiny seeds in the nest (Eg96-BOR-142, 144, 197, 205, 221, 235, 273, 317). I have never encountered colonies which include more than one dealate queen. (Eguchi 2001a)

Identification
Eguchi (2001a) - This species is easily recognised among Indo-Chinese and Indo-Malayan congeners by a combination of the following characteristics: promesonotum of the minor armed with a pair of blunt spines; frons of the major irregularly reticulate; hypostoma of the major bearing a stout (rarely poorly developed) median process; frontal carina of the major horizontal, and extensively overhanging antennal scrobe. The close relationship between P. aristotelis and Pheidole hortensis and its possible relatives is inferred by their exceptional characteristics, i.e., distinctly reticulate ventral faces of midcoxa and hindcoxa in the major.

Two relatively distinct colour forms are observed in both the subcastes; the “brown form” and “dark form” are more or less recognisable sympatrically in Poring and Gunong Rara, Sabah. All of the examined colonies from Halimun CW. Java), and also one colony collected from Lombok, are of the “dark form.” Type series of this species seems to belong to the “brown form.” However, I am at present unsuccessful in finding any other character correlated with this color variation. Therefore, I refrain from concluding their status, and tentatively treat them to be conspecific.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia, Philippines. Oriental Region: Thailand.

Nomenclature

 *  aristotelis. Pheidole aristotelis Forel, 1911a: 43 (s.w.m.) BORNEO. See also: Eguchi, 2001a: 4; Eguchi, 2001b: 34.

Worker
Eguchi (2001a) - Major. Measurements and indices (n=13): TL 2.3-3.0 mm, HL 1.15-1.53 mm, HW 1.05-1.37 mm, SL 0.53-0.68 mm, FL 0.62-0.82 mm, CI 86-94, SI 47-51, FI 55-61. Head in full-face view with almost parallel sides (Fig. 7 A), in profile distinctly impressed on vertex (Fig. 7B). Hypostoma bearing a large median process (Fig. 7C) (rarely the process poorly developed). Clypeus without a median longitudinal carina (rarely with an evanescent carina), with anterior margin hardly concave medially. Eye situated at about 1/3 distance of head (as measured from the mid-point of a transverse line spanning the anteriormost and posteriormost projecting points, respectively (cf. Fig. 2A)); distance between mandibular insertion and anterior margin of eye 1.9-2.3 times as long as maximal diameter of eye. Frontal carina well-developed, horizontal, extending backward to 3/4 distance of head (Fig. 7A). Antennal scrobe deep and extensively overhung by frontal carina. Area around antennal insertion abruptly and deeply depressed. Antenna with 3-segmented club; terminal segment 1.1-1.3 times as long as preceding two segments together. Masticatory margin of mandible with apical and preapical teeth, and a small or evanescent denticle in front of basal angle. Promesonotal dome with an inconspicuous prominence on its posterior declivity (Fig. 7E); dorsal portion of the dome acutely produced laterally (Fig. 7D; but in various degrees). Mesopleuron sometimes with a weak or inconspicuous transverse impression. Propodeal spine 4-5 times as long as diameter of propodeal spiracle, usually blunt apically. Petiole 1.7-1.8 times as long as postpetiole (excluding helcium); petiolar node high, in posterior view emarginate at apex in various degrees. Postpetiole 1.7-2.0 times as broad as petiolar node, acutely produced laterally.

Frons irregularly reticulate, with enclosures punctured weakly and dull; dorsal and dorsolateral faces of occipital lobe reticulate, with smooth and shining enclosures; area between antennal scrobe and eye very weakly reticulate, with punctured and dull enclosures; ventrolateral face of occipital lobe smooth and shining; dorsum of promesonotal dome weakly punctured and weakly shining, and with several transverse or irregular rugulae; lateral face of promesonotal dome and lower part of mesopleuron sometimes smooth and shining; dorsal and declivitous faces of propodeum smooth and shining; remainder of ali trunk weakly punctured and weakly shining; ventral faces of midcoxa and hindcoxa distinctly reticulate; lateral faces of petiole and postpetiole very weakly punctured; dorsa of petiole and postpetiole, and gaster smooth and shining. Outer face of mandible sparsely covered with very short appressed hairs (< 0.02 mm in length), which are much shorter than distance between piligerous punctures; submarginal zone of masticatory margin of mandible with a row of longer appressed to decumbent hairs. Body brown with darker head (especially its anterior part) and with lighter waist and gaster, or dark reddish-brown; flagella and tarsi lighter than alitrunk.

Minor. Measurements and indices (n=13): TL 1.4-1.8 mm, HL 0.50-0.66 mm, HW 0.48-0.63 mm, SL 0.42-0.58 mm, AL 0.62-0.85 mm, FL 0.45-0.66 mm, CI 96-98, SI 87-96, FI 95-110. Head in full-face view slightly concave posteriorly (Fig. 7F); occipital carina evanescent dorsally on head. Clypeus sometimes with a median longitudinal carina, with anterior margin in full-face view slightly convex or truncate medially. Eye situated just in front of midlength of head; distance between mandibular insertion and anterior margin of eye 0.9-1.0 times as long as maximal diameter of eye. Frontal carina sometimes present as an evanescent rugula extending beyond midlength of head. Antennal scrobe present only around antennal insertion. Antenna with 3-segmented club; scape slightly extending beyond posterior border of head; terminal segment 1.1-1.2 times as long as preceding two segments together. Promesonotum forming a low and relatively flat dome, with a pair of spines which are variable in length, blunt apically, and divergent from each other in anterior view; posterior declivity of the dome without a distinct prominence (Fig. 70). Mesopleuron without a transverse impression. Propodeal spine straight or slightly curved, occasionally blunt at apex, usually 5 times (rarely much more than 5 times) as long as diameter of propodeal spiracle. Petiole 1.8-2.0 times as long as postpetiole (excluding helcium); petiolar node in posterior view not emarginate at apex. Postpetiole 1.5-1.7 times as broad as petiole.

Dorsal and lateral faces of head including clypeus punctured, or weakly reticulate with punctured enclosures; alitrunk punctured; lateral face of petiolar pedicel punctured very weakly and shining; dorsum of petiole, and postpetiole and gaster smooth and shining. Body yellowish-brown to brown, or dark brown with lighter mandible; flagella and legs lighter than alitrunk.

Type Material
Eguchi (2001b) - Major, minor and male; Sarawak, Borneo. Seven syntypes (3 majors, 3 minors and 1 male, ) were examined, of which one major is designated as the lectotype.