Pristomyrmex distinguendus, Zettel, H., 2006

Zettel, H., 2006, On the ants (Hymenoptera: Formicidae) of the Philippine Islands: I. The genus Pristomyrmex Mayr, 1866., Myrmecologische Nachrichten 8, pp. 59-68 : 61-62

Pristomyrmex distinguendus sp.n. (Figs. 1, 2)

Type material: holotype (worker): Luzon: Camarines Sur Pr., 20 km E Naga, E Carolina, slopes of Mt. Isarog, 4.III.1999, leg. F. Seyfert (# 19) (NHMW); paratypes: Laguna Pr., Los Banos, Mt. Makiling, from UPLB to Mud Spring, 18.XI.1999, leg. H. Zettel (# 207), 1 [worker] (CZW); Laguna Pr., Los Banos, Mt. Makiling, 500 - 1144 m, 14.XI. 1993, leg. H. Zettel (# 21a), P. collinus det. Wang M., 1 [worker] (CZW); Quezon Pr., Atimonan, Quezon NP, Old Zigzag Road, 27. - 28.I.2002, leg. H. Zettel (# 300), 4 [worker] (CZW, UPLB); Leyte: Baybay, Leyte State University, c. 50 - 100 m, Calbiga-a River, 20. - 21.111.2005, leg. H. Zettel & C. Pangantihon (# 422), 1 [worker] (CZW).

Diagnosis of worker: Ventral surface of clypeus with strongly prominent tooth at centre. Pronotum with pair of short teeth (PSL1 0.02 - 0.05), which shorter than propodeal spines (PSL2 0.05 - 0.09). Dorsum of head and alitrunk smooth and polished, with many long hairs; dorsum of head with scarce punctures (hair pits). Antennal scrobe present, its ventral margin defined by a ridge reaching at least level of centre of eye; petiolar node with two or three pairs of hairs.

Measurements: Holotype worker: TL 3.32, HL 0.80, HW 0.81, CI 101, SL 0.80, SI 100, EL 0.17, PW 0.58, AL 0.87, PPW 0.26, PPL 0.27, PPI 96. - Paratype workers (n = 7): TL 2.84 - 3.41, HL 0.68 - 0.81, HW 0.69 - 0.83, CI 100 - 103, SL 0.70 - 0.85, SI 100 - 104, EL 0.15 - 0.19, PW 0.48 - 0.59, AL 0.75 - 0.90, PPW 0.21 - 0.28, PPL 0.23 - 0.27, PPI 91 - 103.

Description of worker: Head (Fig. 1): Mandibles smooth and shiny. Masticatory margin of mandible with four teeth: strongest apical + second strongest preapical + long diastema + two small basal teeth of similar size that are more or less fused. Basal margin of mandible almost straight, lacking distinct tooth. Clypeus with median longitudinal carina in caudal half (specimens from Luzon) or along entire length (specimen from Leyte). Anterior clypeus margin with median tooth and one pair of lateral teeth. Ventral centre of clypeus with strongly prominent tooth. Palp formula 1, 3. Frontal carinae strong, extending caudad further than level of posterior eye margins. Antennal scrobes present, laterally delimited by distinct ridge reaching caudally at least to level of centre of eye. Frontal lobes very weak; thus, antennal insertion almost entirely exposed.

Antennal scapes, when lying on dorsum of head, slightly surpassing occipital margin of head. Eyes containing c. 8 - 10 ommatidia in longest row. Profile shape of alitrunk and pedicel segments as in Fig. 2. Pronotum with pair of short teeth, PSL1 0.02 - 0.05. Propodeum with pair of spines, PSL2 0.05 - 0.09. Metapleural lobes subtriangular, acute. Dorsum of alitrunk distinctly convex. Petiole in profile with fairly long peduncle, node with weakly developed angles, anterodorsal one on slightly higher level than posterodorsal one. Postpetiole in profile rounded dorsally, in dorsal view broadening from front to back. Dorsum of head smooth and polished, with scattered hair pits which are small in specimens from Luzon and relatively large in specimen from Leyte; on scrobal areas, at least anteriorly, with some transverse rugae. Dorsum of alitrunk smooth and polished, with only very fine hair pits. Petiole, postpetiole, and gaster smooth and shiny. Dorsal surfaces of the head and alitrunk with numerous long erect or suberect hairs. Dorsum of petiolar node with 2 - 3 pairs of hairs; dorsum of postpetiole with 1 - 2 pairs. First gastral tergite lacking erect or suberect hairs. A few pairs of forward projecting hairs present near anterior clypeal margin. Scapes and tibiae with numerous erect to suberect hairs. Colour reddish-brown.

Comparative notes: This species is similar to P. collinus, but differs in a good number of characteristics: The dorsal surface of the head and the alitrunk has many long setae. The pronotal spines are distinctly shorter than the propodeal spines. The antennal scrobes are present and laterally delimited by a ridge reaching caudally at least to level of centre of eye. The clypeus has three teeth, with the median tooth longest (observed also in one specimen of P. collinus, in which dentation of clypeus is more variable than in P. distinguendus sp.n.).

General distribution: endemic to Philippines.