Meranoplus bicolor

Meranoplus bicolor inhabits bare lands, grasslands and sparse forests, and nests in soil. Workers forage on the ground. (Eguchi, Bui and Yamane 2011)

Identification
The most common species in the Oriental Region. It is hardly to be confused with any other congener within the range of its occurrence. It is distinct by the long posteriorly directed spines and the unique pilosity, which are found in no other species.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Indonesia, Malaysia, Singapore. Oriental Region: Bangladesh, Bhutan, Cambodia, India, Laos, Myanmar, Nepal, Pakistan, Sri Lanka, Taiwan, Thailand, Vietnam. Palaearctic Region: China.

Biology
Meranoplus bicolor inhabits bare lands, grasslands and sparse forests, and nests in soil. Workers forage on the ground

Nomenclature

 *  bicolor. Cryptocerus bicolor Guérin-Méneville, 1844a: 425 (w.) INDIA. Smith, F. 1875: 34 (q.m.); Imai, Baroni Urbani, et al. 1984: 6 (k.). Combination in Meranoplus: Smith, F. 1853: 224. Senior synonym of dimicans: Bingham, 1903: 168; Donisthorpe, 1932b: 576; of tarda: Emery, 1892b: 166; of villosus: Roger, 1863b: 39; of fuscescens, lucidus: Schödl, 1998: 372.
 * tarda. Myrmica tarda Jerdon, 1851: 115 (w.) INDIA. Junior synonym of bicolor: Emery, 1892b: 166.
 * dimicans. Meranoplus dimicans Walker, 1859: 375 (w.) SRI LANKA. Junior synonym of bicolor: Bingham, 1903: 168; Donisthorpe, 1932b: 576.
 * villosus. Meranoplus villosus Motschoulsky, 1860a: 115 (q.) SRI LANKA. Junior synonym of bicolor: Roger, 1863b: 39.
 * lucidus. Meranoplus bicolor var. lucida Forel, 1903a: 706 (w.) MYANMAR. Forel, 1909d: 224 (m.). Junior synonym of bicolor: Schödl, 1998: 372.
 * fuscescens. Meranoplus bicolor var. fuscescens Wheeler, W.M. 1930a: 101 (w.) TAIWAN. Junior synonym of bicolor: Schödl, 1998: 372.

Worker
Schödl (1998) - TL: 3.7 - 4.5, HL: 0.76 - 0.93, HW- 85 - 1 05 CI- 89-103 SL- 0.65 - 0.75, SI: 75 - 82, PML: 0.55 - 0.82, PW: 0.7 - 1.0, PMI: 1 16 - 136 AL- 8 -'l 13 (16 measured).

Mandibles striate, armed with four teeth. Mid-portion of clypeus carinulate at least with a tew cannulae; anterior clypeal margin produced into a narrow and concave translucent lamella which is produced into small denticles in the antero-lateral corners Frontal triangle shiny, with few carinulae posteriorly. Head above antennal scrobes trapezoid lateral sides evenly narrowed towards clypeus; ventral part of head (below antennal scrobes) distinctly wider, parallel-sided, the genae distinctly protruding and visible from above. Antennal scrobes posteriorly shagreened, occasionally with additional transverse carinulae or rugae Genae rugulose. Compound eyes situated in posterior half of sides of head close to posterior corners. Maximum diameter of eye 0.2 - 0.26, with 11-14 ommatidia in the longest row.

Promesonotum slightly wider than long, laterally margined and slightly overhanging alitrunk. Declivity of propodeum almost invisible from above, overhung by posterior margin of promesonotal shield (the propodeal spines are visible though). Anterior pronotal corners produced into acute, laterally projecting teeth. At about level of (not visible) promesonotal suture the shield constricted by a lateral indentation which is followed by a short lateral denticle and a large, posteriorly directed straight spine on each side, which may vary considerably in length. In specimens from Sri Lanka the posterior spines occasionally are conspicuously diverging ("dimicans"). Posterior margin of the mesonotum a translucent lamella between the posterior spines, overhanging the propodeum. Propodeal declivity meeting dorsum of alitrunk almost at a right angle. Propodeum shiny throughout, with occasional transverse rugae above or at level of the slender and acute, only little diverging lateral spines. The suture between dorsal alitrunk and propodeum is very well visible beneath posterior mesonotal margin on the propodeal declivity, when viewed from behind.

Petiole in profile cuneate, when viewed from behind, highest in middle, occasionally the crest acute. Both anterior and posterior faces of petiole unsculptured. Postpetiole nodiform, strongly rugulose throughout. Caster densely shagreened, sometimes partly glossy (lucidus).

Dorsum of head longitudinally carinulate to rugulose anteriorly, occipital region with a reticulum, width of meshes ca. 50 - 70 μm. Secondarily the meshes with a distinct shagreenmg. Promesonotal shield and postpetiole strongly reticulate-rugulose, width of meshes ca. 50 - 80 μm, without secondary shagreening. All dorsal surfaces with a shorter suberect, scattered pilosity (ca. 100 - 170 μm) and fewer, extraordinary long, outstanding erect setae (0.3 - 0.6 mm). Femora and tibiae with numerous long, outstanding hairs as well. Populations from different samples vary noticeably in the hair length. Body mostly bicoloured, with head, alitrunk, petiole and postpetiole of a pale to darker ferrugmeous and the gaster piceous. Sometimes appearance of entire body uniformly dark. Differential diagnosis: Meranoplus bicolor is the most common species in the Oriental Region. It is hardly to be confused with any other congener within the range of its occurence. It is distinct by the long posteriorly directed spines and the unique pilosity, which are found in no other species.

Schödl (1999) - Meranoplus bicolor workers with identical label data as the type series of Meranoplus birmanus: TL: 4,1 ± 0.17 (3.8 - 4.4), HL: 0.95 ± 0.037 (0.88 - 0.98), HW: 0.88 ± 0.035 (0.84 - 0.93), CI: 93 ± 1 (90 - 95), SL: 0.70 ± 0.028 (0.66 - 0.73), SI: 80 ± 2 (78 - 83), PML: 0.69 ± 0.040 (0.60 - 0.75), PW: 0.85 ± 0.042 (0.80 - 0.90), PMI: 124 ± 3 (120 - 130), AL: 0.96 ± 0.058 (0.8 - l.0), PTL: 0.42 ± 0.019 (0.39- 0.44), PTH: 0.43 ± 0.024 (0.39 - 0.46), PTI: 96 ± 3 (93 - 100), eyes with 12 - 14 ommatidia in the longest row, maximum diameter of eye 0.21 - 0.25 (12 measured).

Type Material
Schödl (1999) - The holotype worker could not be located.