Myrmica sculptiventris

Two workers were found on mountain meadows at an altitude 2175 m.

Identification
Radchenko and Elmes (2010) - A member of the pachei species group and by the general shape, character of the sculpture and pilosity is quite similar to M. schulzi, but it well differs from that species by its frontal carinae which merges with rugae that extend to the posterior third of head dorsum, do not curve outwards and do not merge with rugae that surround antennal sockets. However, the main diagnostic feature of M. sculptiventris is the rather unusual sculpture of its gaster: the basal third of the first gastral tergite is densely punctated and longitudinally ruguloso-striated; this sculpture gradually reduces posteriorly and the rest of the surface of the tergite has a clear superficial hexagonal microsculpture (seen under magnification > 50 x). It is interesting to note that there are only two other known Myrmica species in the Palaearctic Region with a sculptured gastral tergite: Myrmica luteola and Myrmica brancuccii, but both differ from M. sculptiventris by the absence of the transversal rugosity on the alitrunk dorsum.

Distribution
Sichuan Province, China.

Distribution based on Regional Taxon Lists
Palaearctic Region: China.

Castes
Known only from the worker caste.

Nomenclature

 *  sculptiventris. Myrmica sculptiventris Radchenko & Elmes, 2009a: 72, figs. 11-15 (w.) CHINA. See also: Radchenko & Elmes, 2010: 274.

Worker
Head distinctly longer than broad, with very weakly convex sides and occipital margin and narrowly rounded occipital corners; anterior clypeal margin rounded, slightly prominent, not-notched medially. Upper latero-ventral corner of head rounded, not-pointed (seen in profile). Mandibles with 7-8 teeth. Frontal carinae very feebly curved, merging with rugae that extend to the posterior third of head dorsum, they do not curve outwards and do not merge with rugae that surround antennal sockets. Prons wide, frontal lobes not-extended. Scape relatively long, somewhat longer than head width, gradually though distinctly curved at the base without any trace of lobe or carina.

Alitrunk robust, promesonotum slightly convex (seen in profile), promesonotal suture indistinct (seen from above). Metanotal groove distinct, deep and abrupt. Propodeal lobes rounded apically. Propodeal spines quite long, straight, acute, directed backward at an angle of about 45°. Petiole with distinct peduncle its anterior surface concavc, dorsum of node broadly rounded. Postpetiole subglobular, its anterior and dorsal surfaces forming a regular arch. Spurs of middle and hind tibiae well developed and pectinate.

Frons with dense, fine, slightly sinuous longitudinal rugosity, number of rugae between frontal carinae level with the eyes ca. 20, occiput and temples with fine reticulation, surface between rugae densely and coarsely punctated, appearing dull. Clypeus with longitudinal rugae, surface between them shiny, frontal triangle smooth and shiny. Mandibles longitudinally rugose.

Pronotal dorsum with reticulation, its sides reliculate-punctated. Mesonotal and propodeal dorsum with < 20 moderately coarse transverse sinuous rugae. Lower parts of mesopleura and sides of propodeum with longitudinal rugosity. Surface between rugae on alitrunk with fine punctures, though appearing quite shiny. Petiole and postpetiole densely and coarsely punctated and with short irregular rugulae, appearing dull. Basal third of first gastral tergite densely punctated and longitudinally ruguloso-striate; this sculpture gradually petering out posteriorly, the rest of tergite surface with clear superficial hexagonal microsculpture (see under magnification > 50x).

Head margins above the eyes with short subdecumbent hairs, only occiput sometimes with a few long additional hairs, genae with a few long hairs; alitrunk dorsum with long hairs; petiole with 6-8 long and a few short hairs. Scape and tibiae with subdecumbent hairs. Body colour blackish-brown, appendages somewhat lighter.

Type Material
Holotype, w, China, N Sichuan Prov., W Pingwo, 15 km NW Muzuocangzuxian, Doubuhe riv., 32°41'32"N, 104°22'52"E, 2175 111, 30.vii.2005, leg. Belousov and Kabak (Petersburg); paratype: 1 w with the same label as the holotype.

Etymology
From a combination of the Latin words sculptus = carved or sculptured, and ventris = belly (gaster), to describe the unusual sculpture of the gaster.