Myrmica angulata

In southern China M. angulata nests were found in rotten wood in forests at altitudes 500-1000 m. In northern Vietnam it also lives in mixed forests between 1700 and 2200 m, nests being found in rotten wood, in soil under logs and pieces of bark, or under stones. The altitude difference between the China and Vietnam populations most probably relates to regional climatic differences. (Radchenko and Elmes 2010)

Identification
M. angulata belongs to the ritae-complex of ritae species group, and well differs from all other known species in this complex by the combination of coarse rugosity and dense punctation on the petiole and postpetiole. (Radchenko and Elmes 2010)

Distribution
Southern China and northern Vietnam.

Distribution based on Regional Taxon Lists
Oriental Region: Vietnam. Palaearctic Region: China.

Nomenclature

 *  angulata. Myrmica angulata Radchenko, Zhou & Elmes, 2001: 213, figs. 6-10 (w.) CHINA. Radchenko, Elmes & Bui, 2006: 43 (q.). See also: Radchenko & Elmes, 2010: 88.

Worker
Head slightly longer than broad, with distinctly convex sides and oeeipital margin, and very broadly rounded occipital corners; its upper latero-ventral corners pointed. Anterior clypeal margin shallowly but distinctly notched medially. Frontal carinae feebly curved, frons wide. Antennal sockets surrounded by coarse rugae. Antennal scape extremely long, distinctly longer than head (the relatively longest among all known Myrmica species), quite sharply curved at the base (at an angle < 125°), appearing to be angled but without distinct apex to angle. Mandibles with 9-10 teeth.

Alitrunk long and low, with very weakly convex promesonotal dorsum; promesonotal suture indistinct from above; metanotal groove very shallow. Metapleural lobes project apically and forming sharp tooth. Propodeal spines very long, acute, curved downwards and slightly divergent (from above). Petiole long, low and narrow; its node very long, distinctly longer than peduncle, and with flat dorsum. Postpetiole quite high, subequal to its length, with more or less straight anterior surface and narrowly rounded node dorsum, fig-shape from above. Spurs on middle and hind tibiae well developed and distinctly pectinate.

Whole body with coarse sculpture. Frons between frontal carinae level with the eyes with not less than six rugae. Upper (rear) third of head dorsum with coarse reticulation and sinuous rugae. Clypeus with coarse longitudinal rugae, mandibles coarsely striated while frontal triangle smooth and shiny. Alitrunk dorsum very coarsely reticulate; sides of alitrunk only with sinuous rugae, without reticulation. Petiolar node from above with coarse sinuous mgae, postpetiolar node with concentric rugae and reticulation. Surface of head and alitrunk between rugae not punctured, smooth and shiny. while petiole and postpetiole not coarsely but densely punctured. Gaster smooth and shiny.

Head margins with long outstanding hairs; alitrunk with similar hairs. Antennal scape and tibiae with numerous long subdecumbent hairs; upper margin of scape with suberect hairs. Colour of alitrunk and head from reddish-brown to dark brown, gaster brownish-yellow, antennal and legs reddish.

Queen
Radchenko, Elmes & Bui (2006) - Head longer than broad, with slightly convex sides and almost straight posterior margin, and rounded occipital corners; its upper latero-ventral corners pointed. Anterior clypeal margin slightly convex, notched medially. Frontal carinae very feebly curved, frons wide. Antennal sockets surrounded by rugae. Antennal scape longer than head, sharply curved at the base. Mandibles with 7 - 8 teeth.

Alitrunk relatively long, scutum and scutellum very weakly convex. Metapleural lobes projecting apically and forming sharp tooth. Propodeal spines very long, acute, strongly curved downwards in its apical third. Petiole relatively short and quite high (distinctly shorter than in workers). Postpetiole quite high, subequal to its length, with more or less straight anterior surface and rounded node dorsum, fig-shaped seen from above. Spurs on middle and hind tibiae well developed and distinctly pectinate.

Whole body with coarse sculpture. Frons between frontal carinae level with the eyes, with no less than six rugae. Upper (rear) third of head dorsum with coarse reticulation. Clypeus with coarse longitudinal rugae, mandibles coarsely striated while frontal triangle smooth and shiny. Scutum and scutellum with coarse sinuous rugae and reticulation. Sides of alitrunk with sinuous rugae. Petiolar and postpetiolar nodes with coarse sinuous rugae and reticulation. Surface of head, alitrunk and waist between rugae not punctated, smooth and shiny. Gaster smooth and shiny.

Occipital and lateral margins of head with very long outstanding hairs; alitrunk with similar hairs. Antennal scape and tibiae with numerous long subdecumbent hairs; upper margin of scape with suberect hairs. Body dark brown, with antennae and legs somewhat lighter.

Measurements (mm) and indices of queen (n = 1): HL 1.64, HW 1.44, FW 0.57, FLW 0.60, SL 1.79, AL 2.81, AH 1.71, SCW 1.40, SCL 1.97, HTL 1.65, PL 0.87, PW 0.46, PH 0.53, PPL 0.71, PPW 0.73, PPH 0.78, ESL 0.70, ESD 0.73.

CI 1.14, FI 0.39, FLI 1.06, SI1 1.09, SI2 1.24, PI1 1.63, PI2 0.60, PPI1 0.91, PPI2 1.06, PPI3 1.58, PPI4 0.50, ESLI 0.49, ESDI 1.04, AI 1.65, SCI 1.41

Type Material
Holotype, w, S China, Guangxi Province, Xing An, 500 ill, 7.vii.1994, No.2 (leg. S. Zhou) (LONDON); paratypes: 4 W from the same nest; 1 w, S China, NE Guangxi Province, Hua Ping, 840 ill, 16.viii.l998, HP-25 (leg. J. Fellowes); 2 w, S China, Guangxi Province, Da Yao Shan, 1020 m, 19.ix.1998, DYS-108 (leg. J. Fellowes) (KIEV, GUILIN, ELMES)

Etymology
Radchenko and Elmes (2010) - from the Latin word angulata = angular, with angles, to reflect the more strongly angled base of the scape, compared to most other ritae-group species.