Lophomyrmex indosinensis

This species inhabits well-developed forests, and nests in leaf litter under dead wood on the ground.

Identification
Yamane & Hosoishi (2014) - The specific differences between the species of the L. bedoti group are often very slight. It is highly recommended when identifying species to use series of specimens from colonies. The present new species is similar to Lophomyrmex longicornis, endemic to Borneo, in having a long antennal scape and weak body sculpture. However, in L. longicornis, the hairs on the antennal scape are nearly appressed, the pair of anterior erect hairs on the pronotum are absent, the hairs of the mesonotal dorsum are short, soft and oblique, the propodeal declivity has a pair of complete lateral carinae that are darkened, the posterior margin of the propodeum bears no short hairs, and the propodeal spine is longer, measuring 0.35-0.39 mm (0.21-0.26 mm in L. indosinensis).

Lophomyrmex bedoti (Borneo to Southern Thailand) and Lophomyrmex striatulus (Thailand) are also related to L. indosinensis, but these species can be separated by the following differences:

''L. indosinensis: CI 93-97 (95), SL 0.74-0.76 mm (0.75 mm), SI 100-103 (102). Eye weakly narrowed anteriad, with anterior apex round, EL 0.15-0.16 mm (0.16 mm), number of ommatidia along long axis 8-9, EL/EW 1.46-1.56 (1.51). Area between antennal insertion and eye superficially striate, rather shiny. Vertex and temple very superficially coriaceus and strongly shiny. Seen from above pronotal dorsum with pair of small lateral tubercles; lateral carinae generally weakly developed. Lateral face of pronotum nearly smooth and shiny. With propodeum in profile posterior margin with several suberect hairs (rarely inconspicuous); propodeal spine more or less distinctly upward-directed with its apex distinctly higher than propodeal dorsum.

L. bedoti: CI 94-100 (96), SL 0.64-0.70 mm (0.67 mm), SI 87-94 (91). Eye distinctly narrowed anteriad, EL 0.13-0.16 mm (0.15 mm), number of ommatidia along long axis 6-7 (rarely 8), EL/EW 1.60-1.83 (1.72). Area between antennal insertion and eye finely but distinctly striate, and mat. Vertex and upper gena weakly sculptured and weakly shiny. Seen from above pronotal dorsum margined laterally with irregular carinae that are darkened. Lateral face of pronotum longitudinally, finely striate, or nearly smooth, and shiny. With propodeum in profile posterior margin generally without suberect hairs; propodeal spine more or less distinctly upward-directed with its apex distinctly higher than propodeal dorsum.

L. striatulus: CI 94-103 (98), SL 0.58-0.62 mm (0.61 mm), SI 84-91 (88). Eye distinctly narrowed anteriad often with pointed apex, EL 10.14-0.16 mm (0.15 mm), number of ommatidia along long axis 6-7, EL/EW 1.63-2.11 (1.87). Area between antennal insertion and eye distinctly striate, and mat. Vertex and upper gena more strongly sculptured and very weakly shiny. Seen from above pronotal dorsum margined laterally with irregular carinae that are darkened. Lateral face of pronotum longitudinally, finely but distinctly striate, and nearly mat. With propodeum in profile posterior margin generally without suberect hairs (sometimes with a few very fine hairs present); propodeal spine nearly backward-directed with its apex only slightly higher than propodeal dorsum.

Keys

 * Key to Lophomyrmex species
 * Key to Lophomyrmex of South China, Indo-China and Thailand

Distribution based on Regional Taxon Lists
Oriental Region: Vietnam.

Nomenclature

 *  indosinensis. Lophomyrmex indosinensis Yamane & Hosoishi, 2014: 65, figs. 1-3 (w.) VIETNAM.

Worker
Measurements (in mm; n=5; mean in parentheses). Head width 0.72-0.76 (0.74), Head length 0.76-0.80 (0.78), Eye length (EL) 0.15-0.16 (0.16), Eye width (EW) 0.10-0.11 (0.10), Scape length (SL) 0.74-0.76 (0.75), Propodeal spine length 0.21-0.26 (0.24), Hind tibial length (0.70-0.74 (0.73). Cephalic index (CI) 93-97 (95), Scape index (SI) 100-103 (102), EL/EW 1.45-1.56 (1.51).

Head slightly longer than broad, with straight to very weakly convex posterior margin in profile. Clypeus with anterior margin bearing median process. Mandible with large apical tooth followed by smaller second tooth, low triangular third tooth, and several small denticles of variable size. Eye longer than broad but not very elongate, anteriorly not pointed, with 8-9 ommatidia along long axis. Antennal scape relatively long, extending beyond posterior margin of head by much more than length of antennal pedicel (second segment). Pronotum laterally with small tubercle (often with another smaller one); short carina(e) may exists around tubercles but generally weakly developed. In profile mesonotum more or less distinctly elevated at 2/5 length of its slope so that anterior concavity can be seen just behind pronotum. Propodeum with weakly convex dorsal outline; lateral carina on declivity weak, not darkened; propodeal spines nearly as long as propodeal height, diverging with apical portion weakly curved outwardly, obliquely upward-directed with apex distinctly higher than propodeal dorsum. With waist in profile, dorsal outline of petiole shallowly concave, peduncle not distinctly demarcated from node; node apically round or at most with indistinct anterodorsal angle; postpetiole globular with evenly curved dorsal outline, nearly as long as high.

Head weakly and superficially sculptured; area between eye and clypeus longitudinally striate; frontal lobe rather strongly sculptured; temple behind eye and venter of head almost smooth and strongly shiny. Clypeus finely transversely striate mixed with superficial microreticulation except in basal and apical smooth portions. Mandible densely covered with longitudinal striae and mat except for narrow shiny belt along basal and masticatory margins. Pronotum entirely superficially sculptured and shiny; mesothrax, metapleuron and propodeum densely sculptured except for propodeal declivity rather smooth and shiny; mesopleuron more regularly punctate than other parts and interspaces smooth and shiny. Waist extensively sculptured; anterior and dorsal faces of postpetiolar node more or less smooth. Legs superficially sculptured to smooth except for coxae where sculpture is stronger (fore coxa with much weaker sculp-ture). Dorsum of head with many long standing hairs; hairs on lateral and ventral faces of head tend to be decumbent. Suberect hairs on antennal scape dense and long, some of which are longer than scape width. Pronotum in frontal view with a pair of anterior erect hairs located at short distance from lateral margin and often additional hairs located more mesad (some of these hairs may be missing); mesonotum with two pairs of short but stiff erect hairs; propodeal dorsum without long erect hairs; propodeal declivity in profile with several short and soft hairs.

Body concolorous brown to dark brown; in paler individuals mesosoma yellowish brown, and head and gaster dark; mandible reddish brown; antenna and legs paler than mesosoma.

Type Material
Holotype: worker, Hon Ba National Park (900 m alt.), Khánh Hóa, S. Vietnam (12˚06’N, 108˚58’E), 20.ii.2014, S. Hosoishi leg., ex leaf litter, SH14-Vie-24, deposited in (Entomological Collection of the Institute of Ecology and Biological Resources, Hanoi, Vietnam). Paratypes: 14 workers and 2 winged queens, same data as holotype (,, IEBR, , ). Nontype material: 5 workers, same locality and collector, SH14-Vie-20.