Diacamma brevistriatum

Little is known about the biology of .

Identification
Laciny et al. (2015) - Relatively small species (TL 10.0–11.8 mm). Trunk black, without metallic shimmer. Standing setae relatively short. Trunk coarsely striate from genae to gaster tergite 1. Head short; sides posteriorly of eye strongly convex. Posterior of head longitudinally striate until narrowly truncated hind margin; striae deeply engraved between flat ridges; hind margin narrow, its ends almost flat, forming small, blunt angles. Eyes relatively small, but slightly surpassing lateral outline of head. Clypeus entirely punctured, rectangularly projecting, at apex slightly depressed, its tip rounded. Mandible with fine striation. Entire mesosoma with coarse striation. Striae on pronotum disc arranged concentrically, those in centre transverse. Striation on mesopleura and propodeum sides strongly oblique. Petiole stout, its teeth moderately long, relatively distant; subpetiolar process shallowly concave, anterior corner acute, posterior corner weakly protruding, obtuse or slightly acute. Gaster tergite 1 with coarse semi-circular striation. Gaster tergite 2 with paired groups of longitudinal striae behind middle.

In most characters this strongly rugose species is similar to many other species of the Diacamma rugosum complex. The most peculiar and diagnostic character of D. brevistriatum is found on gaster tergite 2 which bears a pair of patches with short striae. In Diacamma rugosum sculptum from Aru Island, there is a continuous striation of tergite 2, similar to Diacamma ceylonense, and some reduced striae on tergite 3. In Diacamma holzschuhi from Laos a striation on tergite 2 rarely occurs as an individual aberration, but this species differs from D. brevistriatum by short petiolar spines (SpLI 29–34 vs. 35–43) and a differently shaped and strongly hirsute subpetiolar process.

Distribution
West Malaysia: Kelantan, Pahang, Perak, Selangor.

Diacamma brevistriatum is only recorded from montane areas in West Malaysia.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Malaysia.

Nomenclature

 *  brevistriatum. Diacamma brevistriatum Laciny, Pal & Zettel, 2015: 112, figs. 35-39 (w.) WEST MALAYSIA.
 * Status as species: Zettel, et al. 2016: 166.

Worker
Holotype: TL 11.80; HW 2.01; HL 2.51; EL 0.54; SL 2.74; PH 1.63; PL 1.00; PW 1.11; SpD 0.72; SpL 0.44; WL 3.85; MTL 2.15. Indices: CI 80; SI 137; PI 61; SpDI 66; SpLI 40; EI 26. Measurements of paratypes (n = 11): TL 9.98–11.74; HW 1.88–2.09; HL 2.36–2.59; EL 0.49–0.56; SL 2.48–2.77; PH 1.43–1.67; PL 0.87–1.04; PW 1.04–1.15; SpD 0.71–0.81; SpL 0.38–0.47; WL 3.46–3.85; MTL 1.92–2.15. Indices: CI 78–83; SI 130–137; PI 58–63; SpDI 65–73; SpLI 35–43; EI 25–28.

Structures: Head relatively short; sides strongly convex behind eyes. Relatively coarse rugae present from genae to gaster tergite 1. Longitudinal striae posteriorly of eyes deeply engraved between flat ridges, reaching the narrowly truncated hind margin. Hind margin narrow, its ventral ends almost flat, forming very small, blunt angles. Clypeus entirely, finely punctured, shiny, strongly protruding into an approximately rectangular, sharp apex; just behind tip shallowly impressed; tip narrowly rounded. Mandible with some strong punctures and with fine striation. Striation on mesosoma, including sides, very coarse. Pronotum concentrically striate, in most specimens with some short, transverse rugae in centre. Rugae on mesosoma sides strongly oblique. Posterior face of propodeum separated from sides by distinct carinae. Petiole very stout, its teeth moderately long and relatively distant; subpetiolar process with shallowly concave ventral outline bearing short pilosity; anterior corner acute, posterior corner weakly protruding, rather variable from obtuse to slightly acute; in ventral aspect with paired lateral carinae (in some specimens reduced posteriorly), without or with indistinct median carina. Gaster tergite 1 with very coarse, semi-circular rugae, along posterior margin densely punctured. Gaster tergite 2 shiny, with very fine microsculpture and with distinct paired groups of short longitudinal striae on disc behind middle. In one specimen a similar, but weaker striation also present on gaster tergite 3.

Pilosity: Trunk and legs with numerous, relatively short standing setae; those on petiole and gaster longer than those on mesosoma; setae on scape very short. Short appressed pilosity weakly developed, but denser on head in front of eyes, mesonotum, dorsal face of propodeum, posterior margins of pronotum and gaster tergite 1, and on the other gastral tergites.

Colour: Trunk black, without metallic shimmer, but shiny. Very narrow hind margins of gaster tergites and sternites yellowish brown. Mandibles and legs (except for black fore coxae) dark reddish brown or blackish. Clypeus and antennae varying in colour from black to dark reddish brown.

Type Material
All specimens from West Malaysia: Holotype (worker,, CASENT 0915958), Perak, Cameron Highland, 40 km SE of Ipoh, Banjaran Titi Wangsa, Ringlet, 900 m a.s.l., 25.III.–3.IV.2002, leg. P. Cechovský. Paratypes: 28 workers (NHMW), same locality data; 18 workers (NHMW), same locality, 25.IV.–5.V.2001, leg. P. Cechovský; 1 worker (NHMW), Perak, Cameron Highland, 25 km NE of Ipoh, Banjaran Titi Wangsa mountains, Korbu mountain, 1200 m a.s.l., 27.I.–2.II.1999, leg. P. Cechovský; 1 worker, Selangor, N Kuala Lumpur, Ulu Gombak, 16.II.1993, leg. H. Zettel (#1); 5 workers (CZW), Kelantan, 30 km NW of Gua Musang, Ulu Lalat, Kampong Sungai Om, 800–1000 m a.s.l., 21.VI.–14.VII.2010, leg. P. Cechovský; 1 worker (CZW), same locality, 22.V.–14.VI.2012, leg. P. Cechovský; 2 workers (CZW), Pahang, 50 km NE of Kuala Rompin, Endau Rompin N.P., Gunung Kerung, Kampong Tebu Hitam, 400 m a.s.l., 9–30.IV.2008, leg. P. Cechovský; 2 workers (NHMW), Pahang, 30 km SE of Ipoh, Banjaran Titi Wangsa, Tanah Rata, 1500 m a.s.l., 14–15.III.2002, leg. P. Cechovský.

Etymology
This species is named for the characteristic patches of short striae on gaster tergite 2.