Pheidole cariniceps

This species inhabits well-developed lowland and hill forests, and nests in the soil. (Eguchi 2001) Heterick & Kitching (2022) collected this species in a pitfall trap within a lowland dipterocarp forest in Brunei.

Identification
Eguchi (2001) - The closest relative of this species is the sympatric Pheidole aglae, but in the latter antennal scrobe of the major is not margined below by distinct carina; propodeal spine of the major has narrow base; and prominence on posterior declivity of promesonotum, and dorsum of propodeum each bear more than two pairs of erect or suberect hairs in the minor.

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

Worker
Minor

Images from AntWeb
Major

Nomenclature

 *  cariniceps. Pheidole cariniceps Eguchi, 2001b: 41, fig. 10 (s.w.m.) BORNEO.

Worker
Major (n=10): TL 3.7-4.6 mm, HL 1.57-1.85 mm, HW 1.45-1.63 mm, SL 0.83-0.88 mm, FL 1.27-1.38 mm, CI 88-93, SI 54-58, FI 83-89. Head broadest at 1/2-3/5 distance of head (as measured from the mid-point of a transverse line spanning the anteriormost and posteriormost projecting points, respectively (cf. Fig. 2A)) (Fig. 10A), in profile gently impressed on vertex (Fig. 10B). Hypostoma without distinct median processes. Clypeus rarely with a median longitudinal carina, with anterior margin emarginate medially. Eye situated at about 1/3 distance of head; distance between mandibular insertion and anterior margin of eye 1.5-1.7 times as long as maximal diameter of eye. Frontal carina distinct, extending backward to about 2/3 distance of head. Antennal scrobe shallow, running along frontal carina, margined below by a distinct carina along its anterior half (Fig. 10A). Antenna with 3-segmented club; scape extending backward to about 3/5 distance of head; terminal segment ca. 0.9 times as long as preceding two segments together. Masticatory margin of mandible with apical and preapical teeth, and a denticle in front of basal angle.

Promesonotal dome with a distinct prominence on its posterior declivity (Fig. 10C); the prominence in anterior view not or very weakly concave medially. Mesopleuron without a distinct transverse impression. Propodeal spine elongate-triangular, with broad base, ca. 3.5 times as long as diameter of propodeal spiracle (Fig. 10C). Petiole cuneiform, 1.3-1.5 times as long as postpetiole (excluding helcium); petiolar node in posterior view weakly emarginate at apex. Postpetiole in dorsal view subpentagonal, 2.1-2.3 times as broad as petiolar node.

Frons longitudinally rugose, with very weakly punctured interspaces; vertex and dorsal and lateral faces of occipital lobe rugoso-reticulate, with very weakly punctured enclosures; promesonotum smooth and shining with transverse rugulae dorsally; mesopleuron and lateral face of propodeum weakly rugoso-reticulate, with distinctly punctured enclosures; petiole (excluding smooth anterodorsal face), postpetiole and anterior part of first gastral tergite weakly punctured. Outer face of mandible covered with appressed hairs, which are 0.04-0.08 mm in length and much shorter than distance between piligerous punctures; submarginal zone of masticatory margin of mandible with a row of longer decumbent hairs. Body yellowish-brown to reddish-brown, with much darker gaster; legs a little lighter than alitrunk.

Minor (n=12): TL 2.0-2.4 mm, HL 0.59-0.74 mm, HW 0.46-0.55 mm, SL 0.81-0.97 mm, AL 0.88-1.10 mm, FL 0.84-1.08 mm, CI 73-77, SI 170-186, Fl183-200. Head in full-face view oval; occipital carina forming a well-developed flange (Fig. 10D, E). Clypeus without a median longitudinal carina, with anterior margin in full-face view truncate medially. Eyes 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 and antennal scrobe present only around antennal insertion. Antenna with 3-segmented club; scape extending beyond posterior border of head by more than its 1/3 length; terminal segment 0.8-0.9 times as long as preceding two segments together. Promesonotal dome with a gentle prominence on its posterior declivity (Fig. 10F). Mesopleuron without a transverse impression. Propodeal spine elongate-triangular, ca. 1.5 times as long as diameter of propodeal spiracle. Petiole cuneiform, 1.2-1.3 times as long as postpetiole (excluding helcium); petiolar node low, in posterior view not emarginate at apex. Postpetiole in dorsal view subpentagonal, 1.8-2.2 times as broad as petiolar node.

Head including clypeus and promesonotum smooth and shining; remainder of alitrunk punctured; lateral faces of petiole and postpetiole weakly punctured; dorsa of petiole and postpetiole, and gaster almost smooth and shining. Prominence on posterior declivity of promesonotum, and dorsum of propodeum each bearing a pair of standing hairs (Fig. 10F). Body yellowish-brown with a little lighter alitrunk; legs sometimes a little lighter than alitrunk.

Type Material
Holotype Major, colony: Eg98-BOR-840, Logging area nr. Ranau, Sabah, E. Malaysia (Borneo), K. Eguchi leg., 1998, deposited in. Paratypes 9 majors, 15 minors and 5 males from the same colony to which the holotype belongs, deposited in, , , , , , and UMS.

References based on Global Ant Biodiversity Informatics

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 * Bruhl C.A. 2001. Leaf litter ant communities in tropical lowland rain forests in Sabah, Malaysia: effects of forest disturbance and fragmentation. PHD thesis Wurzburg Universitat, 168 pp.
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