Tetramorium pacificum

Hita Garcia and Fisher (2011) - Tetramorium pacificum has a vast distribution range in the Oriental and Indo-Australian regions, and, as the species epithet suggests, is present in most Pacific island systems. In addition, T. pacificum has been introduced to Canada, California, Florida, Central America and the Caribbean, Switzerland (one record from the zoo in Zurich), and the Malagasy region. Schlick-Steiner et al. (2006b) point out that it might not be possible to delimit its native range due to frequent transfers by humans. However, its distribution suggests the native range of this species is most probably in the Indo-Australian region, including the island systems of the Pacific Ocean (McGlynn, 1999).

Identification Keys including this Taxon
Key to US Tetramorium species

Distribution based on Regional Taxon Lists
Australasian Region: Australia, New Caledonia. Indo-Australian Region: Borneo, Cook Islands, Fiji, French Polynesia, Indonesia, Krakatau Islands, Micronesia (Federated States of), New Guinea, Niue, Palau, Philippines, Samoa, Solomon Islands, Tonga, Vanuatu, Wallis and Futuna Islands. Nearctic Region: United States. Oriental Region: India, Sri Lanka, Thailand. Palaearctic Region: China.



Nomenclature

 *  pacificum. Tetramorium pacificum Mayr, 1870b: 976 (w.q.) TONGA. Imai, Kubota, et al. 1985: 47 (k.). Senior synonym of subscabrum: Bolton, 1977: 102. See also: Schlick-Steiner, Steiner & Zettel, 2006: 182; Hita Garcia & Fisher, 2011: 24.
 * subscabrum. Tetramorium pacificum var. subscabrum Emery, 1893f: 246 (w.) SRI LANKA. Subspecies of pacificum: Wheeler, W.M. 1909d: 340. Junior synonym of pacificum: Bolton, 1977: 102; Schlick-Steiner, Steiner & Zettel, 2006: 187.

Worker
Hita Garcia and Fisher (2011) - HL 0.780 - 0.870 (0.845); HW 0.665 - 0.760 (0.737); SL 0.565 - 0.645 (0.626); EL 0.155 - 0.190 (0.178); PW 0.530 - 0.570 (0.554); WL 0.970 - 1.120 (1.067); PSL 0.215 - 0.255 (0.236); PTL 0.300 - 0.355 (0.332); PTH 0.290 0.340 (0.318); PTW 0.245 - 0.275 (0.259); PPL 0.270 - 0.300 (0.290); PPH 0.275 - 0.310 (0.296); PPW 0.310 - 0.350 (0.330); CI 85 - 90 (87); SI 81 - 88 (85); OI 23 - 25 (24); PSLI 26 - 30 (28); PeNI 44 - 49 (47); LPeI 101 - 106 (104); DPeI 75 - 82 (78); PpNI 56 - 62 (59); LPpI 93 - 101 (98); DPpI 110 - 120 (114); PPI 123 - 132 (127) (20 measured).

Head distinctly longer than wide (CI 85 - 90). Anterior clypeal margin with distinct median impression. Frontal carinae strongly developed, either reaching posterior head margin or ending shortly before. Antennal scrobes weakly developed, narrow and shallow, posterior and ventral margins never differentiated, not reaching posterior head margin. Antennal scapes of moderate length, not reaching posterior margin of head (SI 81 - 88). Eyes of moderate size (OI 23 - 25), with 11 to 14 ommatidia in longest row. Metanotal groove not impressed. Propodeal spines long, relatively narrow and acute (PSLI 26 - 30). Propodeal lobes elongate-triangular to triangular and acute. Node of petiole nodiform, in profile anterior and posterior faces roughly parallel, anterodorsal angle situated much lower than posterodorsal, dorsum slopes upwards posteriorly, node weakly longer than high (LPeI 101 - 106), in dorsal view node distinctly much longer than high (DPeI 75 - 82). Postpetiole in profile rounded, weakly higher than long to as high as long (LPpI 93 - 101), in dorsal view noticeably wider than long (DPpI 110 - 120) and much more voluminous than petiolar node (PPI 123 - 132). Mandibles unsculptured, smooth, and shiny. Clypeus with 3 well-developed longitudinal rugae. Most of head with reticulate-rugose sculpturation, area between frontal carinae close to posterior clypeal margin often more longitudinally rugose but always with cross-meshes; ground sculpturation on head weak and faint. Mesosoma and waist segments reticulate-rugose without any distinct ground sculpturation. First gastral tergite with basigastral costulae, rest of gaster completely unsculptured, smooth, and shiny. All dorsal surfaces of head, mesosoma, waist segments, and gaster with numerous long, standing hairs, depending on population hairs either fine or thick; hairs on antennal scapes and tibiae appressed to suberect. Colouration dark brown to blackish brown.

Type Material
Hita Garcia and Fisher (2011):

Syntype workers, queen, TONGA, Tongatabu (NMW, BMNH) [examined].

Tetramorium pacificum var. subscabrum Syntype workers, SRI LANKA, Kandy and Colombo (E. Simon) (MHNG) [examined].