Pheidole inornata

A colony of Pheidole inornata was found nesting with Odontomachus procerus in the Sago Mountain, West Sumatra(Satria et al. 2015). It has also been found with Odontomachus rixosus (Eguchi 2001).

Identification
Eguchi (2001) - This species with a general habitus is similar to Pheidole aglae and Pheidole plagiaria, but in P. aglae posterior margin of head of the major is more distinctly emarginate, and occipital carina of the minor forming a well-developed flange; and in P. plagiaria posteriormost part of occipital lobe of the major is almost transversely rugose.

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

Biology
Eguchi (2001) - This species has so far been collected from Sayap Kinabalu (ca. 1000 m alt.) and Tambunan in Sabah, and Khao Yai N. P. in Thailand. Colonies of this species and Odontomachus rixosus nested together under rocks along the main trail in Sayap (e.g., Eg96-BOR-060, 064), or within a rotting log near the headquarters (Kbao Yai N. P.). In Thailand and Java Pheidole tandjongensis is also a partner of O. rixosus (F. Ito, pers. com., 1999; Sk. Yamane, pers. com., 2000). The presence of the Pheidole species is, however, not indispensable for O. rixosus, because O. rixosus usually nests solely in other localities in Borneo.

Worker
Minor

Images from AntWeb
Major

Nomenclature

 *  inornata. Pheidole inornata Eguchi, 2001b: 66, fig. 22 (s.w.m.) BORNEO.

Worker
Major (n=5): TL 3.1-3.9 mm, HL 1.35-1.48 mm, HW 1.20-1.34 mm, SL 0.93-0.96 mm, FL 1.22-1.32 mm, CI 87-91, SI 71-80, FI 94-101. Head broadest at about 3/5 distance of head (as measured from the mid-point of a transverse line spanning the anteriormost and posteriormost projecting points, respectively), posterior margin of head in full-face view weakly concave (Fig. 22A); head in profile not impressed on vertex (Fig. 22B). Hypostoma with a pair of small median processes. Clypeus without a distinct median longitudinal carina, with anterior margin emarginate medially. Eye situated just behind 1/3 distance of head; distance between mandibular insertion and anterior margin of eye 1.7-2.0 times as long as maximal diameter of eye. Frontal carina distinct, extending backward to about 3/4 distance of head (Fig. 22A). Antennal scrobe weak, running along frontal carina. Antenna with 3-segmented club; scape extending backward to about 4/5-5/6 distance of head; terminal segment 0.8-0.9 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. 22C); the prominence in anterior view not concave medially. Mesopleuron with a weak or inconspicuous transverse impression. Propodeal spine horn-like, slightly curved, 2.5-3 times as long as diameter of propodeal spiracle. Petiole cuneiform, 1.3-1.4 times as long as postpetiole (excluding he1cium); petiolar node low, in profile rounded and in posterior view weakly or very weakly emarginate at apex. Postpetiole in dorsal view subpentagonal, angulate laterally, 1.9-2.0 times as broad as petiolar node.

Frons and gena longitudinally rugose; dorsal and lateral faces of occipital lobe reticulate; mandible rugose from its base toward masticatory margin; promesonotal dome in dorsal view largely smooth and shining, with several transverse rugulae; mesopleuron and lateral face of propodeum irregularly and weakly rugose, with enclosures punctured weakly and dull; lateral face of petiole weakly punctured; dorsum of petiole smooth and shining; dorsum of postpetiole very weakly punctured and weakly shining; gaster smooth and shining. Outer face of mandible covered with decumbent hairs, which are 0.06-0.12 mm in length and (a little) longer than distance between piligerous punctures. Body yellowish-brown or reddish-brown, with darker mandibles (sometimes gaster also darker); legs a little lighter than alitrunk.

Minor (n=5): TL 2.5-2.6 mm, HL 0.70-0.75 mm, HW 0.55-0.60 mm, SL 0.90-0.95 mm, AL 1.00-1.06 mm, FL 0.96-1.03 mm, CI 78-81, SI 153-163, FI 168-176. Head in full-face view oval (Fig. 22D); occipital carina distinct. Clypeus without a median longitudinal carina, with anterior margin in full-face view truncate or slightly concave medially. Eye situated at about mid length of head; distance between mandibular insertion and anterior margin of eye ca. 1.1 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 low prominence on its posterior declivity (Fig. 22E). Mesopleuron with an inconspicuous transverse impression. Propodeal spine elongate-triangular, directing upward, 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 profile rounded and in posterior view not emarginate at apex. Postpetiole in dorsal view subpentagonal, 1.9-2.1 times as broad as petiolar node.

Clypeus smooth and shining; large part of dorsum of head above subocular level punctured very weakly but shining, and venter of head below subocular level smooth and shining; promesonotal dome largely smooth and shining (partly very weakly punctured); mesopleuron and lateral face of propodeum weakly punctured; lateral face of petiole very weakly punctured; dorsum of petiole, and postpetiole and gaster smooth and shining. Body yellowish-brown; legs a little lighter than alitrunk.

Type Material
Holotype Major, colony: Eg96-BOR-064, Sayap Kinabalu (1000 malt.), Sabah, E. Malaysia (Borneo), K. Eguchi leg., 1996, deposited in. Paratypes 16 majors, 18 minors and 15 males from the same colony to which the holotype belongs, deposited in, , , , , , and VMS.

References based on Global Ant Biodiversity Informatics

 * 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. 2003. A study on the male genitalia of some Asian species of Pheidole (Hymenoptera, Formicidae, Myrmicinae). Sociobiology 41: 317-355.
 * Hashimoto Y., and M. Mohamed. 2011. Ground-dwelling ant diversity in Maliau Basin, Borneo: evaluation of hand-sorting methods to estimate ant diversity. Tropics 19(2): 85-92.
 * Jaitrong W., and T. Ting-Nga. 2005. Ant fauna of Peninsular Botanical Garden (Khao Chong), Trang Province, Southern Thailand (Hymenoptera: Formicidae). The Thailand Natural History Museum Journal 1(2): 137-147.
 * Jaitrong W.; Nabhitabhata, J. 2005. A list of known ant species of Thailand. The Thailand Natural History Museum Journal 1(1): 9-54.
 * Pfeiffer M., and D. Mezger. 2012. Biodiversity Assessment in Incomplete Inventories: Leaf Litter Ant Communities in Several Types of Bornean Rain Forest. PLoS ONE 7(7): e40729. doi:10.1371/journal.pone.0040876
 * Pfeiffer M., and D. Mezger. 2012. Biodiversity Assessment in Incomplete Inventories: Leaf Litter Ant Communities in Several Types of Bornean Rain Forest. PLoS ONE 7(7): e40729. doi:10.1371/journal.pone.0041084
 * 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.