Pheidole quadrensis

This species inhabits well-developed forests in lowlands. It nests in rotting twigs and wood blocks on the forest floor, and stores up a number of tiny seeds in its nest (Eg97-BOR-471, 535). I have never encountered colonies which include more than one dealate queen. (Eguchi 2001)

Identification
Eguchi et al. (2016) - Distinction from Pheidole leloi: In the major, propodeal spine in lateral view broadly based, pointed apically. In the minor, petiolar node in lateral view blunt at apex, and in posterior view not emarginate at apex. Pheidole quadrensis sensu Eguchi (2001) is highly heterogenous in worker morphology and undoubtedly constitutes a species complex. Thus, it needs to be revised based on future intensive sampling in Sumatra and the Malay Peninsula.

Eguchi (2001) - P. quadrensis is closely related to Pheidole lokitae, Pheidole quadricuspis, Pheidole sperata, Pheidole acantha and Pheidole spinicornis, and several undescribed species, and they are recognisable among Indo-Chinese and Indo-Malayan congeners by a combination of the characteristics noted under Pheidole lokitae. They are, according to Emery (1921), related to Austro-Malayan Pheidole quadrispinosa group and Pheidole cervicornis group. P. quadrensis is well distinguished form the Bornean relatives by the characters given in the key.

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

Worker
Minor

Nomenclature

 *  quadrensis. Pheidole quadrensis Forel, 1900a: 25 (s.) INDONESIA (Sumatra). Emery, 1900d: 682 (w.). Combination in P. (Pheidolacanthinus): Forel, 1913k: 45. See also: Eguchi, 2001b: 96.

Worker
Eguchi (2001) - Major (n=10): TL 4.1-5.1 mm, HL 1.83-2.07 mm, HW 1.90-2.28 mm, SL 0.99-1.08 mm, FL 1.32-1.47 mm, CI 103-110, SI 47-53, FI 64-71. Head broadest at about 2/3 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 weakly emarginate medially (Fig. 38A); head in profile not impressed on vertex (Fig. 38B). Hypostoma with a pair of stout median processes (Fig. 38C). Clypeus 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 1.8-2.1 times as long as maximal diameter of eye. Frontal carina inconspicuous, extending backward to about 2/3 distance of head. Antennal scrobe present only around antennal insertion. Antenna with 3-segmented club; scape reaching about 3/5-2/3 distance of head; terminal segment 0.9-1.1 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. Promesonotal dome with a pair of spines (Fig. 38D, E), with a prominence on its posterior declivity (Fig. 38B); the prominence in anterior view weakly or very weakly concave medially. Mesopleuron with an inconspicuous transverse impression. Propodeal spine pointed apically, with broad base, 5-6 times as long as diameter of propodeal spiracle (Fig. 38E). Petiole cuneiform, 1.5-1.7 times as long as postpetiole (excluding helcium); petiolar node in posterior view not emarginate at apex; subpetiolar process low, truncate anteriorly. Postpetiole 1.8-2.1 times as broad as petiolar node.

Frons and gena longitudinally rugose, with smooth and shining interspaces; occipital lobe reticulate, with smooth and shining enclosures; alitrunk irregularly rugoso-reticulate; petiole smooth and shining anterodorsally, weakly rugose and weakly shining posterodorsally, and punctured and dull laterally; postpetiole largely punctured, or punctured and dull laterally and transversely rugose dorsally; dorsum of gaster and anterior part of first gastral sternite distinctly punctured and dull. Outer face of mandible sparsely covered with decumbent or suberect hairs, which are 0.08-0.11 mm in length and almost as long as, or a little longer than, distance between piligerous punctures. Body reddish-brown to dark reddish-brown; antennae and legs a little lighter than alitrunk.

Minor (n=13): TL 2.4-2.9 mm, HL 0.75-0.89 mm, HW 0.67-0.78 mm, SL 0.90-1.14 mm, AL 1.00-1.20 mm, FL 0.96-1.15 mm, CI 83-91, SI 131-148, PI 138-155. Head in full-face view oval (Fig. 38F), with distinct occipital carina. CIypeus with a median longitudinal carina, with anterior margin in full-face view weakly convex medially. Eyes situated at about midlength of head; distance between mandibular insertion and anterior margin of eye 1.0-1.1 times as long as maximal diameter of eye. Frontal carina and antennal scrobe present only around antennal insertion. Antenna with 3-segmented club; in full-face view scape extending beyond posterior border of head by more than its 1/3 length; terminal segment 0.9-1.0 times as long as preceding two segments together. Promesonotal dome with a pair of spines, with an inconspicuous prominence on its posterior declivity (Fig. 38G). Mesopleuron without a transverse impression. Propodeal spine horn-like, sometimes slightly recurved, 4-5 times as long as diameter of propodeal spiracle (Fig. 38G). Petiole in profile cuneiform, ca. 1.4 times as long as postpetiole (excluding helcium); petiolar node in posterior view not emarginate at apex; its posterior face usually margined dorsally and laterally. Postpetiole 1.8-2.2 times as broad as petiolar node.

Clypeus smooth and shining with several rugulae, or very weakly rugose and weakly shining; remainder of head reticulate; alitrunk largely reticulate, but area between promesonotal spines smooth and shining; lateral faces of petiole and postpetiole weakly punctured; dorsa of petiole and postpetiole, and gaster smooth and shining. Body sparsely bearing standing hairs. Body brown, reddish-brown or dark brown; antennae and legs a little lighter than alitrunk.

Type Material
Eguchi (2016) - ; Indonesia, Sumatra, Kajactonam, Sumatra; M. Weber leg.; 1888 holotype (major), CASENT0907768.

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
 * Donisthorpe H. 1947. Pheidole (Pheidolacanthinus) striatus sp. n. from New Guinea, with notes on the subgenus Pheidolacanthinus F. Smith (Hym., Formicidae). Entomologist's Monthly Magazine 83:172-174.
 * 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.
 * Eguchi K., B. Tuan Viet, E. Oguri, and S. Yamane. 2016. The first discovery of the “Pheidole quadricuspis group” in the Indo-Chinese Peninsula (Insecta: Hymenoptera: Formicidae: Myrmicinae). Revue suisse de Zoologie 123(1): 45-55.
 * Eguchi K., and S. Yamane. 2003. Species diversity of ants (Hymenoptera, Formicidae) in a lowland rainforest, northwestern Borneo. New Entomol. 52(1,2): 49-59.
 * 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.
 * Forel A. 1900. Un nouveau genre et une nouvelle espèce de Myrmicide. Annales de la Société Entomologique de Belgique 44: 24-26.
 * Hashimoto Y., Y. Morimoto, E. S. Widodo, and M. Mohamed. 2006. Vertical distribution pattern of ants in a Bornean tropical rainforest (Hymenoptera: Formicidae). Sociobiology 47(3): 697- 710.
 * Kishimoto-Yamata K., F. Hyodo, M. Matsuoka, Y. Hashimoto, M. Kon, T. Ochi, S. Yamane, R. Ishii, and T. Itioka. 2012. Effects of remnant primary forests on ant and dung beetle species diversity in a secondary forest in Sarawak, Malaysia. Journal of Insect Conservation DOI 10.1007/s10841-012-9544-6
 * Pfeiffer M., D. Mezger, and J. Dyckmans. 2013. Trophic ecology of tropical leaf litter ants (Hymenoptera: Formicidae) - a stable isotope study in four types of Bornean rain forest. Myrmecological News 19: 31-41.
 * 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.0040927
 * 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.0041013
 * 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
 * Woodcock P., D. P. Edwards, T. M. Fayle, R. J. Newton, C. Vun Khen, S. H. Bottrell, and K. C. Hamer. 2011. The conservation value of South East Asia's highly degraded forests: evidence from leaf-litter ants. Phil. Trans. R. Soc. B. 366: 3256-3264.