Messor ponticus

Identification
Steiner et al. (2018) - Worker and queen. Usually darker than Messor ibericus, Messor mcarthuri, and Messor structor. Generally, body more finely sculptured than in all other species, especially head. Discrimination from M. structor and Messor muticus by shorter 1st funicular segment, by base of scape without lobe. Discrimination from all other species by reduced number of standing setae on side of head and, in some individuals, by shallower clypeal notch. Mesopleuron more regularly rugose than in all other species. Microsculpture of 1st gastral tergite similar to M. structor and M. muticus but clearly less imbricate than in M. ibericus and M. mcarthuri.

Worker. Generally larger than M. ibericus, M. structor, and M. muticus, and similarly sized as M. mcarthuri. Discrimination from all other species by postocular region of head mostly lacking costae and costulae, almost smooth and shining in major worker. For individuals difficult to discriminate from M. structor or M. muticus using qualitative morphology, morphometrics-based linear discriminant functions are available.

Queen. Larger than M. ibericus, similar in size to all other species.

Distribution based on Regional Taxon Lists
Palaearctic Region: Bulgaria, Romania, Turkey, Ukraine.

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

Nomenclature

 *  ponticus. Messor ponticus Steiner et al., 2018: 399, figs. 2, 5ab, 5bb, 5cb, 5db, 5eb, 5fb, Table S1 (w.q.m.) BULGARIA.

Description
Worker and queen. Colour: Dark brown to black, gaster always blackish. Size: Large. Head: Usually finely sculptured with longitudinal, regular costae below eye level, but can be reduced in minor worker; postocular region can lack sculpture entirely, sometimes smooth and shining. Very sparse, short, erect setae on side of head and genae, sometimes lacking almost entirely. Scape: Base without lobe. Laterally directed, tooth-like processus in major worker, less distinct in minor worker. 1st funicular segment short and flattened, longer than 2nd segment, but shorter than 2nd and 3rd segment together. Clypeus: Median notch very shallow, often lacking entirely. Pronotum: Middle smooth and shining; laterally mostly regular, bended, fine costae, can be reduced to shallow microreticulation in minor worker. Mesonotum: Densely sculptured throughout; costae transverse, with punctuation amongst. Mesopleuron: Regular transverse costulae with slightly irregular, well-developed punctuation among them; costulae can be very fine even in major worker. Propodeum: Sometimes angulated even in minor worker, in major worker almost tooth-like, with bended costae. Surface of 1st gaster tergite: Base imbricate, middle smooth and shining with isolated snow-flakes-like structure. Covered with sparse, thick and long, whitish hairs, some of which decumbent or subdecumbent.

Queen: Metanotum: Densely sculptured throughout, costae transverse, punctuation amongst. Anepisternum and katepisternum: Middle smooth and shining, side with longitudinal costulae.

Male: Anepisternum: Microreticulate, but shining. Katepisternum: With longitudinal costulae; shining even if microsculpture among some costulae.

Type Material
Holotype. Bulgaria BG016 viz. Strouma valley SW Zemen; 06.10.2004  leg. T. Ljubomirov; “14759”; Holotypus  ”Messor“ ”ponticus“ [on the reverse side: Top specimen design. Csősz 2016].

Paratypes: 11 workers labelled as holotype: Bulgaria BG016 viz. Strouma valley SW Zemen; 06.10.2004 leg. T. Ljubomirov (5 paratype workers: NHMW; 6 paratype workers: ).

Etymology
Named for its distribution area around the Black Sea (Lat.: Pontus Euxinus).