Messor muticus

Identification
Steiner et al. (2018) - Worker and queen. Colour similar to Messor ponticus, usually darker than Messor ibericus, Messor mcarthuri, and Messor structor. Discrimination from M. ibericus, M. mcarthuri, and M. ponticus by base of scape with rounded lobe, long 1st funicular segment, and by coarser sculpture of mesopleuron, from M. ponticus by abundant standing setae on side of head. Surface of 1st gastral tergite less imbricate, than in M. ibericus and M. mcarthuri, similarly to M. structor and M. ponticus.

Worker. Similarly sized as M. ibericus and M. structor, smaller than M. mcarthuri and M. ponticus. For individuals difficult to discriminate from M. ponticus or M. structor using qualitative morphology, morphometrics-based linear discriminant functions is available. M. structor and M. muticus are well separated longitudinally and ecologically.

Queen. Larger than M. ibericus, similarly sized as M. mcarthuri, M. ponticus, and M. structor. Discrimination from M. ibericus by reduced reticulation and rugosity of anepisternum and katepisternum.

Distribution based on Regional Taxon Lists
Palaearctic Region: Armenia, Kazakhstan, Kyrgyzstan, Romania, Russian Federation, Ukraine.

Biology
mtDNA: Ten haplotypes of COI (1375 bp) known; (GenBank).

Nomenclature

 *  muticus. Myrmica mutica Nylander, 1849: 39 (w.q.m.) RUSSIA.
 * Combination in Aphaenogaster: Roger, 1863b: 29.
 * Combination in Stenamma (Messor): Emery, 1898c: 126.
 * Combination in Messor: Ruzsky, 1903b: 315; Emery, 1908e: 456.
 * As unavailable (infrasubspecific) name: Emery, 1908e: 456; Forel, 1911d: 347; Emery, 1912f: 96; Emery, 1921f: 73; Santschi, 1921a: 110; Soudek, 1922: 35; Karavaiev, 1926b: 101; Santschi, 1926f: 291; Soudek, 1931: 8; Santschi, 1934d: 275.
 * Subspecies of structor: Emery, 1898c: 142; Ruzsky, 1903b: 315; Ruzsky, 1904b: 4; Emery, 1915h: 1; Bondroit, 1918: 151; Stärcke, 1926: 86 (in key); Santschi, 1934d: 275; Novák & Sadil, 1941: 82 (in key); Hamann & Klemm, 1976: 671.
 * Subspecies of rufitarsis: Arnol'di, 1977b: 1643 (in key).
 * Junior synonym of rufitarsis: Emery, 1921b: 211; Bernard, 1967: 144.
 * Junior synonym of structor: Mayr, 1855: 464; Nylander, 1856b: 85; Smith, F. 1858b: 162; Roger, 1863b: 29; Emery & Forel, 1879: 462; Atanassov & Dlussky, 1992: 114; Bolton, 1995b: 255; Radchenko, 2007: 31; Legakis, 2011: 11.
 * Status as species: Agosti & Collingwood, 1987b: 271 (in key); Borowiec, L. & Salata, 2012: 514; Borowiec, L. 2014: 110 (error); Steiner et al., 2018: 400.

Description
Steiner et al. (2018) - Worker and queen. Colour: Head and mesosoma brown to brownish red, gaster dark brown. Major workers can be dark brown entirely. Size: Medium sized. Head: Mostly entirely costate. In major and frequently in medium worker, costae on much of postocular region. However, in minor and sometimes in medium worker, costae mostly reduced in postocular region; head almost smooth, with fine costulae and microreticulate, frequently shining. Erect setae abundant on side of head from occiput to mandibular insertion. Scape: Base with rounded, laterally-downward directed lobe; very distinct in minor worker; can be reduced in major worker. 1st funicular segment long and flattened, almost as long as 2nd and 3rd segment together. Clypeus: Median notch well defined; can be shallow in minor worker. Pronotum: Middle mostly coarsely and irregularly costate throughout. Mesonotum: Coarsely and irregularly costate throughout. Mesopleuron: Coarsely sculptured with irregular transverse costae; shallow punctuation among costae. Minor workers less costate with almost no punctuation. Propodeum: Mostly smoothly rounded; in major worker, often obliquely rounded, rarely angled. Surface of 1st gaster tergite: Basis imbricate, middle sometimes with isolated snow-flakes-like structure. Covered with yellowish, thin, sparse hairs, some of which decumbent and subdecumbent in some individuals.

Queen: Metanotum: Coarsely and irregularly costate. Anepisternum and katepisternum: Sides covered with fine costulae, middle smooth and shining.

Male: Anepisternum and katepisternum: At least sides covered with fine costulae, sometimes middle smooth and shining.

Type Material
Steiner et al. (2018) - 1q, Ross. mer., Mus. Zool. H:fors, spec. typ. No. 5894, Myrmica mutica Nyl., T, Ross. mer. Motsch., coll. Nyland. 1 m, Ross. mer., Mus. Zool. H:fors, spec. typ. No. 5895, Myrmica mutica Nyl., T, Ross. mer. Motsch., coll. Nyland. 1w, Ross. mer., Mus. Zool. H:fors, spec. typ. No. 5896, Myrmica mutica Nyl., T, Ross. mer. Motsch., coll. Nyland.