Messor ibericus

Multi-coloniality and swarming flights reported from Mainz, Germany (Heller, 1971). In Greece, Salata & Borowiec (2019) found this to be the most common species of the Messor structor group, well distinguished by small gynes. Noted from various types of habitats, mostly open such as pastures, roadsides, stone hills, ruderal places in villages but also inside open pine forests, olive plantations, open oak forests from sea coast up to 1450 m a.s.l.

Identification
Steiner et al. (2018) - Worker and queen. Colour generally lighter than in Messor muticus and Messor ponticus. Rugosity of cuticular surface more regular than in Messor structor, rugae sometimes parallel. Discrimination from M. structor and M. muticus by short 1st funicular segment and by base of scape without lobe but with a small tooth-like processus. Discrimination from all four species by finely costate base of mesopleuron. Head costate almost throughout unlike in M. ponticus, and costae less regular than in Messor mcarthuri. Setae more abundant on side of head than in M. ponticus, similarly to M. structor, M. muticus, and M. mcarthuri. Petiole not as costulate as in M. mcarthuri. Discrimination from M. ponticus, M. structor, and M. muticus by 1st gastral tergite’s entirely imbricate surface.

Worker. Size similar to M. structor and M. muticus, major workers usually smaller than in M. ponticus and M. mcarthuri. For individuals difficult to discriminate from M. structor using qualitative morphology, linear discriminant function is available.

Queen. Smallest and only species with microreticulate and not shining surface of anepisternum and katepisternum among all five species.

Distribution based on Regional Taxon Lists
Palaearctic Region: Bulgaria, Croatia, France, Germany, Greece, Italy, Romania, Slovenia, Spain , Switzerland.

Biology
mtDNA: Six haplotypes of COI (1375 bp) known; (Gen-Bank).

Nomenclature

 *  ibericus. Messor structor var. ibericus Santschi, 1931a: 4 (w.m.) SPAIN.
 * [First available use of Messor barbarus subsp. structor var. iberica Emery, 1922c: 92 (w.) SPAIN; unavailable (infrasubspecific) name.]
 * Santschi, 1931a: 4 (m.).
 * As unavailable (infrasubspecific) name: Emery, 1924c: 164.
 * Subspecies of structor: Santschi, 1931a: 4; Santschi, 1932c: 69.
 * Subspecies of barbarus: Ceballos, 1956: 302.
 * Status as species: Collingwood, 1978: 68, 81 (in key); Bolton, 1995b: 254; Borowiec, L. 2014: 107; Steiner, Csösz, et al. 2018: 398 (redescription).
 * Senior synonym of novaki: Steiner, Csösz, et al. 2018: supplementary material, 8.
 * novaki. Messor structor subsp. novaki Finzi, 1929: 92 (w.) CROATIA.
 * Junior synonym of structor: Atanassov & Dlussky, 1992: 114; Bolton, 1995b: 256.
 * Junior synonym of ibericus: Steiner, Csösz, et al. 2018: supplementary material, 8.

Taxonomic Notes
Salata & Borowiec (2019):
 * As Messor structor (Latreille, 1798): Borowiec and Salata, 2012: 514 (misinterpretation).
 * As Messor cf. structor: Borowiec and Salata, 2014: 511, 2017b: 214, 2018a: 8; Bračko et al., 2016: 23.

Description
Steiner et al. (2018) - Worker and queen. Colour: Head and mesosoma light brown to brownish red, gaster brown to dark brown. Major worker mostly dark brown. Queen dark brown. Size: Medium. Queen small, similar in size to major. Head: Entirely sculptured with mostly parallel costae, which usually bifurcate above eye level. Sculpture disappears gradually above eye level, at least on vertex. Postocular region on side of head can lack costae, but microsculpture always present. Erect setae abundant on side of head from occiput to mandibular insertion. Scape: Base without lobe, tooth-like processus directed mostly downward. 1st funicular segment short and flattened, longer than 2nd segment, but shorter than 2nd and 3rd segments together. Clypeus: Median notch well-defined, but shallow in some minor workers. Pronotum: Median costae often arched, middle of pronotum often smooth. Mesonotum: Densely sculptured throughout, costae transverse and mostly parallel. Mesopleuron: Densely sculptured with fine, irregular costulae with dense punctuation among them, even in minor worker. Propodeum: Mostly rounded; rarely angulated in major worker; smoothly rounded in minor worker. Parallel costae on side. Surface of 1st gaster tergite: Entire surface imbricate.

Queen: Metanotum: Densely sculptured throughout, costae transverse and mostly parallel. Anepisternum: Microreticulate. Katepisternum: Middle microreticulate, side additionally with parallel longitudinal costulae.

Type Material
Steiner et al. (2018) - 1 lectotype worker by present designation, upper individual on pin with two workers labelled “Cataluna Gavá: VII.94. (Nov.) A. Cabrera Aphaenogaster   (Messor) barbara  r. sordida Forel. A. Cabrera, Cataluna Gavá: VII.94. (Nov.) A. Cabrera  Aphaenogaster  (Messor) barbara  r. sordida Forel. A. Cabrera, SYNTYPUS  Messor structor  var. ibericus Santschi, 1931, Museo Genova   coll. C. Emery  (dono 1925)”; 1 paralectotype worker by present designation, lower individual on same pin as lectotype,.