Pheidole ghigii

Eguchi (2001) - Within Borneo this species has so far been collected only from well-developed lowland forests in Sarawak. In Bali Satria et al. (2015) found two colonies of Odontomachus simillimus near the base of living trees in a cacao plantation that "coexisted with colonies of the myrmicine Pheidole ghigii."

Identification
Eguchi (2001a) - This species is characterised among Indo-Chinese and Indo-Malayan congeners by a combination of the following characteristics: hypostoma of the major bearing a pair of large median processes; posterior declivity of promesonotal dome of both the subcastes bearing a distinct prominence; promesonotal dome of the minor with a pair of low tubercles dorsolaterally; eye of both the subcastes relatively small; distance between mandibular insertion and anterior margin of eye 2.0-2.1 times as long as maximal diameter of eye in the major, and 1.3-1.5 times in the minor; postpetiole in both the subcastes massive.

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

Worker
Minor

Nomenclature

 *  ghigii. Pheidole ghigii Emery, 1900d: 685 (s.w.) INDONESIA (Sumatra). See also: Eguchi, 2001a: 10; Eguchi, 2001b: 55.

Worker
Eguchi (2001a) - Major (n=3): TL 2.4-3.1 mm, HL 1.30-1.47 mm, HW 1.22-1.39 mm, SL 0.60-0.65 mm, FL 0.82-0.88 mm, CI 94-95, SI 47-49, FI 63-67. Head broadest around 3/5-2/3 distance of head (as measured from the mid-point of a transverse line spanning the anteriormost and posteriormost projecting points, respectively) (Fig. 17 A), in profile not impressed on vertex (Fig. 17B). Hypostoma bearing a pair of large median processes (Fig. 17C). Clypeus without a median longitudinal carina, with anterior margin weakly concave medially. Eye situated just in front of 1/3 distance of head; distance between mandibular insertion and anterior margin of eye 1.9-2.2 times as long as maximal diameter of eye. Frontal carina inconspicuous, extending backward to 3/5 distance of head. Antennal scrobe only present around antenna I insertion. Antenna with 3-segmented club; scape extending backward to 1/2-3/5 distance of head; terminal segment ca. 1.1 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. Promesonotum forming a high dome, with a distinct prominence on its posterior declivity (Fig. 17D); the prominence in anterior view not or very weakly concave medially; each dorsolateral portion of the dome weakly produced outward. Mesopleuron without a distinct transverse impression. Propodeal spine horn-like, 2.5-3 times as long as diameter of propodeal spiracle. Petiole almost as long as postpetiole (excluding helcium); petiolar node in posterior view distinctly emarginate at apex. Postpetiole 2.2-2.4 times as broad as petiolar node.

Frons longitudinally rugose; vertex, and dorsal and lateral faces of occipital lobe reticulate; dorsum of promesonotum irregularly rugose, with smooth and shining enclosures; dorsal and declivitous faces of propodeum weakly punctured; remainder of alitrunk weakly rugoso-reticulate, with weakly punctured enclosures; petiole (excluding its smooth and shining anterior face) and postpetiole weakly punctured and dull; gaster largely smooth and shining. Outer face of mandible sparsely covered with appressed hairs, which are 0.04-0.06 mm in length and shorter than distance between piligerous punctures; submarginal zone of masticatory margin of mandible with appressed to decumbent hairs. Body yellowish-brown with darker mandibles and clypeus.

Minor (n=6): TL 1.6-1.7 mm, HL 0.58-0.60 mm, HW 0.53-0.55 mm, SL 0.55-0.59 mm, AL 0.75-0.80 mm, FL 0.59-0.62 mm, CI 90-93, SI 105-109, FI 110-114. Head in full-face view slightly concave posteriorly (Fig. 17E); occipital carina evanescent dorsally on head. Eye situated just in front of midlength of head; distance between mandibular insertion and anterior margin of eye 1.3-1.5 times as long as maximal diameter of eye. Clypeus with a weak median longitudinal carina, with anterior margin in full-face view slightly convex medially. Frontal carina and antennal scrobe present only around antennal insertion. Antenna with 3-segmented club; in full-face view scape extending beyond posterior border of head by its 1/5 length; terminal segment ca. 1.1 times as long as preceding two segments together. Promesonotum forming a high dome, with a pair of low tubercles dorsolaterally, with a low but distinct prominence on its posterior declivity (Fig. 17F). Mesopleuron without a distinct transverse impression. Propodeal spine horn-like, 2-2.5 times as long as diameter of propodeal spiracle. Petiole 0.9-1.0 times as long as postpetiole (excluding helcium) (Fig. 17F); petiolar node in posterior view not emarginate at apex. Postpetiole massive, in dorsal view subhexagonal, 2.3-2.5 times as broad as petiolar node.

Dorsal and lateral faces of head including clypeus smooth and shining; posterolateral face of head very weakly punctured; promesonotum smooth and shining with irregular rugulae dorsally, and weakly punctured laterally and anterodorsally; remainder of alitrunk punctured; lateral face of petiole weakly punctured; dorsum of petiole, and postpetiole and gaster smooth and shining. Body light yellowish-brown to yellowish-brown, with a little darker mandibles (sometimes gaster also darker than head and alitrunk).

Type Material
Eguchi (2001a) - Specimens examined BORNEO. Sarawak, Malaysia: Bako N. P., 1 major and 18 minors (GC),, 1993; Old Tower Region, Lambir Hills N. P., 1 major and 9 minors (GC), SKY, 1993/50 ha plot, 1 major and 6 minors (GC), SKY, 1993.

References based on Global Ant Biodiversity Informatics

 * Chapman, J. W., and Capco, S. R. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monogr. Inst. Sci. Technol. Manila 1: 1-327
 * Eguchi K. 2001. A revision of the Bornean species of the ant genus Pheidole (Insecta: Hymenoptera: Formicidae: Myrmicinae). Tropics Monograph Series 2: 1-154.
 * Eguchi K. 2001. A taxonomic study on Asian Pheidole (Hymenoptera, Formicidae): new synonymy, rank changes, lectotype designations and redescriptions. Insecta Koreana 18: 1-35.
 * Emery C. Formiche raccolte da Elio Modigliani in Sumatra, Engano e Mentawei. Annali del Museo Civico di Storia Naturale 40: 661-722.
 * Emery, C. "Formiche raccolte da Elio Modigliani in Sumatra, Engano e Mentawei." Annali del Museo Civico di Storia Naturale Giacomo Doria (Genova) (2) 20, no. 40 (1900): 661-722.
 * Pfeiffer M.; Mezger, D.; Hosoishi, S.; Bakhtiar, E. Y.; Kohout, R. J. 2011. The Formicidae of Borneo (Insecta: Hymenoptera): a preliminary species list. Asian Myrmecology 4:9-58
 * Satria R., H. Kurushima, H. Herwina, S. Yamane, and K. Eguchi. 2015. The trap-jaw ant genus Odontomachus Latreille (Hymenoptera: Formicidae) from Sumatra, with a new species description. Zootaxa 4048(1): 001-036.