Pristomyrmex rugosus, 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 : 63-64

Pristomyrmex rugosus sp.n. (Figs. 3, 4)

Type material: holotype (worker): Leyte: Leyte Pr., Baybay, Mt. Pangasugan, Calbiga-a River, 50 - 200 m, 12.II. 2000, leg. H. Zettel (# 236) (NHMW); paratypes: same data, 5 [worker] (CZW); same locality, c. 50 - 100 m, Calbiga-a River, 20. - 21.111.2005, leg. H. Zettel & C. Pangantihon (# 422), 2 [worker] (CZW, USC).

Diagnosis of worker: Ventral surface of clypeus with prominent tooth at centre. Pronotum with pair of long spines (PSL1 0.15 - 0.17), which are distinctly longer than short propodeal teeth (PSL2 0.04 - 0.05). Dorsum of head and alitrunk with foveolate-reticulate sculpture or rugoreticuletum, with long, relatively dense pilosity; petiolar node and postpetiolar nodes smooth, each with several pairs of hairs on dorsum. First gastral tergite without erect or suberect hairs.

Measurements: Holotype worker: TL 4.26, HL 1.05, HW 1.02, CI 98, SL 1.09, SI 106, EL 0.22, PW 0.72, AL 1.14, PPW 0.31, PPL 0.34, PPI 89. - Paratype workers (n = 7): TL 4.01 - 4.26, HL 0.94 - 1.05, HW 0.94 - 1.02, CI 97 - 101, SL 1.01 - 1.06, SI 102 - 107, EL 0.19 - 0.21, PW 0.63 - 0.70, AL 1.00 - 1.12, PPW 0.27 - 0.30, PPL 0.30 - 0.32, PPI 90 - 97.

Description of worker: Head (Fig. 3): Mandibles more or less striate. Masticatory margin of mandible with four teeth: strongest apical + second strongest preapical + long diastema + two small basal teeth of similar size. Basal margin of mandible almost straight, lacking distinct tooth. Clypeus with strong median longitudinal carina and one pair of more or less developed lateral carinae. Anterior clypeus margin with median tooth and three pairs 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. Both frontal carinae and lateral ridge confluent with strong rugoreticulum of head. Frontal lobes absent, antennal insertion entirely exposed. Antennal scapes, when lying on dorsum of head, surpassing occipital margin of head. Eyes containing 10 - 12 ommatidia in longest row. Profile shape of alitrunk and pedicel segments as in Fig. 4. Pronotum with pair of relatively long spines, PSL1 0.15 - 0.17. Propodeum with pair of teeth, PSL2 0.04 - 0.05. Metapleural lobes subtriangular, apex weakly to moderately rounded. Dorsum of alitrunk anteriorly convex, posteriorly straight. Petiole in profile with fairly long peduncle, node with weakly developed, high anteriodorsal angle, posteriodorsally rounded. Postpetiole in profile rounded dorsally, in dorsal view broadening from front to back. Dorsum of head, except for transversely rugous scrobal areas, and alitrunk with coarse rugoreticulum. Sides of pronotum similarly reticulate, but rugae less high. Petiole, postpetiole, and gaster smooth and shiny. Dorsal surfaces of head, alitrunk, petiole, and postpetiole with numerous long erect or suberect hairs. 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 dark reddish-brown.

Comparative notes: This species is most similar to P. sulcatus , but differs in having relatively long pronotal spines, dorsally more rounded node of petiole, and relatively large eyes with more ommatidia (10 - 12 vs. 6 - 7 in P. sulcatus fide Wang 2003). From typical P. sulcatus , it can be easily distinguished by the numerous setae on the petiole and postpetiole and by the more reticulate dorsum of the pro-mesonotum (with coarser longitudinal ridges in syntype of P. sulcatus ). However, judging from the specimens deposited in NHMW and identified by M. Wang, P. sulcatus as redescribed and interpreted by Wang (2003) is a variable species and may include further unrecognized taxa. From three other species, which are recorded from the Philippines, the new species differs as follows: from P. bicolor in the much shorter pronotal spines, in smaller size, and the presence of a central tooth on the ventral surface of the clypeus; from P. brevispinosus in the absolutely and relatively longer pronotal spines; and from P. costatus in the presence of a central tooth on the ventral surface of the clypeus, slightly shorter pronotal spines, and more coarse rugoreticulum on dorsum of alitrunk.

General distribution: endemic to Philippines.