Pheidole merimbun

Nothing is known about the biology of .

Identification
Eguchi (2001) - This species, together with Pheidole planidorsum, has a combination of the following characteristics: promesonotal dome of the minor relatively low and flat dorsally; hypostoma of the major bearing three median processes (medianmost one poorly developed in this species); posterior declivity of promesonotal dome without a distinct prominence in both the subcastes; occipital carina of the minor almost absent dorsally on head; body relatively small. This species is closely related to P. planidorsum, but in the latter occipital lobe of the major is reticulate.

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

Nomenclature

 *  merimbun. Pheidole merimbun Eguchi, 2001b: 79, fig. 29 (s.w.) BRUNEI.

Worker
Major (n=4): TL 2.3-2.6 mm, HL 1.00-1.08 mm, HW 0.90-0.95 mm, SL 0.45-0.48 mm, FL 0.59-0.60 mm, CI 88-90, 51 47-51, FI 63-66. 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) (Fig. 29A), in profile slightly impressed on vertex (Fig. 29B). Hypostoma bearing three median processes, of which medianmost one is poorly developed. Clypeus without a median longitudinal carina, with anterior margin very weakly concave medially. Eye situated just behind 1/3 distance of head; distance between mandibular insertion and anterior margin of eye ca. 1.5 times as long as maximal diameter of eye. Frontal carina inconspicuous, extending backward to 3/5-2/3 distance of head. Antennal scrobe inconspicuous, running along frontal carina. Antenna with 3·segmented club; scape extending backward to 3/5-2/3 distance of head; terminal segment 1.1-1.2 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, without a distinct prominence on its posterior declivity (Fig. 29C); each dorsolateral portion of the dome produced outward. Mesopleuron with a weak transverse impression. Propodeal spine elongate triangular, broadly based, 1.5-2 times as long as diameter of propodeal spiracle. Petiole 1.5-1.6 times as long as postpetiole (excluding helcium); petiolar node in posterior view slightly emarginate at apex. Postpetiole 1.6-1.7 times as broad as petiolar node.

Frons, vertex and gena longitudinally rugose; occipital lobe completely smooth and shining; dorsum of promesonotal dome smooth and shining with several transverse rugulae; lateral face of promesonotal dome smooth and shining; lower part of mesopleuron partly smooth and shining; remainder of alitrunk weakly punctured and weakly shining; 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, which are ca. 0.03 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 with darker mandible, clypeus and gaster.

Minor (n=4): TL 1.5-1.6 mm, HL 0.48-0.50 mm, HW 0.43-0.45 mm, SL 0.41-0.42 mm, AL 0.61-0.63 mm, FL 0.43-0.45 mm, CI 89-95, SI 92-95, PI 94-101. Head in full-face view weakly convex posteriorly (Fig. 29D); occipital carina evanescent dorsally on head. Clypeus without a median longitudinal carina, with anterior margin in full-face view almost truncate medially. Eye situated just in front of midlength of head; distance between mandibular insertion and anterior margin of eye ca. 0.9 times as long as maximal diameter of eye. Frontal carina and 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 relatively low and flat dorsally (Fig. 29E), in dorsal view very weakly margined laterally, without a prominence on its posterior declivity. Mesopleuron without a distinct transverse impression. Propodeal spine small, pointed, almost twice as long as diameter of propodeal spiracle. Petiole 1.6-1.7 times as long as postpetiole (excluding helcium); petiolar node in posterior view not emarginate at apex. Postpetiole ca. 1.5 times as broad as petiolar node.

Clypeus and frons smooth and shining; remainder of dorsum of head sparsely sculptured by evanescent longitudinal rugulae and shining; promesonotal dome smooth and shining, with several rugulae anteriorly and laterally; remainder of alitrunk punctured; lateral face of petiolar pedicel weakly punctured; dorsum of petiole, and postpetiole and gaster smooth and shining. Body yellowish-brown.

Type Material
Holotype Major, colony: Eg99-BOR-086, Merimbun Heritage Park, BRUNEI, K. Eguchi leg., 1999, deposited in. Paratypes 3 majors and 4 minors from the same colony to which the holotype belongs, deposited in, MBD and.

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., S. Yamane, and S.Y. Zho. 2007. Taxonomic revision of the Pheidole rinae Emery complex. Sociobiology 50 (1): 275-284.
 * 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.
 * Helms J. A., S. M. Helms, N. I. Fawzi, Tarjudin, F. Xaverius. 2017. Ant community of an Acacia mangium forest in Indonesian Borneo. Serangga 22(1): 147-159.
 * 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
 * Tanaka H. O., S. Yamane, and T. Itioka. 2012. Effects of a fern-dwelling ant species, Crematogaster difformis, on the ant assemblages of emergent trees in a Bornean tropical rainforest. Ann. Entomol. Soc. Am. 105(4): 592-598.