Messor concolor

The biology of this species is poorly known. Workers were collected at midday, in the dry riverbed located in Imbros Gorge. Area was overgrown by phrygana. Most probably, as in all Cretan Messor species, nest was located in soil (Salata & Bororiec, 2019). Pashaei Rad et al. (2018) found this species in Iran on parkland ground in a moderate rainfall area.

Identification
Salata and Borowiec (2019) - Messor concolor, a member of the M. semirufus group, is characterized by smooth and shiny head sculpture, lack of rugosity between striation on mesosoma and low number of erect setae on mesosoma dorsum and first gastral tergite. From most members of the semirufus group it differs in almost uniform body coloration with mesosoma not or only partly paler colored than head and gaster. There are four Mediterranean known taxa with similar body coloration: Messor semirufus, Messor nahali, Messor ebeninus and Messor dentatus. Messor concolor can be easily distinguished from them, and from other species of the M. semirufus group, in having dull gaster with very dense microreticulation.

Distribution
Salata and Borowiec (2019) - Species described from Crete (Emery, 1908). Most recent data confirms certain presence of this species on Crete, and, in our opinion, M. concolor should be treated as a species endemic to this island. However, based on literature data, this taxon was also recorded from Bulgaria and former Yugoslavia (Agosti and Collingwood, 1987), Turkey (Santschi, 1921; Schaff, 1924; Baroni Urbani, 1964; Agosti and Collingwood, 1987), Syria and Lebanon (Tohmé and Tohmé, 1981). Due to long-lasting misinterpretation of features considered to be specific for this species all literature records should be interpreted with high caution. In our collection, we have numerous samples collected from the Balkans and Asia Minor, and in none of them we could observe such dense gaster microreticulation as on specimens collected on Crete. Therefore, based on collected evidences, we consider M. concolor to be a Cretan endemic species, but cannot exclude the possibility that it could be an Aegean species (sensu Fattorini, 2000).

Distribution based on Regional Taxon Lists
Palaearctic Region: Greece.

Nomenclature

 * . Messor semirufus var. concolor Santschi, 1927c: 229.
 * [First available use of Messor barbarus subsp. semirufus var. concolor Emery, 1908e: 448 (s.w.m.) SYRIA, GREECE (Crete I.); unavailable (infrasubspecific) name.]
 * As unavailable (infrasubspecific) name: Emery, 1915h: 1; Wheeler, W.M. & Mann, 1916: 170; Emery, 1921f: 72; Santschi, 1921a: 110.
 * Subspecies of semirufus: Baroni Urbani, 1964a: 1; Hamann & Klemm, 1976: 671.
 * Junior synonym of semirufus: Baroni Urbani, 1974: 227.
 * Junior synonym of wasmanni: Collingwood & Agosti, 1996: 322; Kiran & Karaman, 2012: 21; Borowiec, L. & Salata, 2013: 385 (in text).
 * Status as species: Tohmé, G. & Tohmé, H. 1981: 143; Agosti & Collingwood, 1987a: 54; Agosti & Collingwood, 1987b: 271 (in key); Bolton, 1995b: 253; Markó & Csösz, 2002: 116; Paknia, et al. 2008: 154; Vonshak, et al. 2009: 42; Lapeva-Gjonova, et al. 2010: 15; Legakis, 2011: 10; Borowiec, L. & Salata, 2012: 513; Tohmé, G. & Tohmé, 2014: 134; Salata & Borowiec, 2018c: 46; Salata & Borowiec, 2019a: 56 (redescription).

Salata and Borowiec (2019) - Species described from Crete (Emery, 1908), in the original description M. concolor was distinguished from other members of the Messor semirufus group based on matt gaster surface. Unfortunately, this feature was wrongly interpreted, what resulted in very complicated taxonomical history. Study on type specimens and new material led us to the conclusion that the Cretan specimens with matt gaster surface maintain their separateness. Hence, we consider M. concolor a separate species, endemic to Crete.

Worker
Salata and Borowiec (2019) - (n = 15): HL: 1.952 ± 0.1 (1.711–2.145); HW: 1.984 ± 0.2 (1.71–2.216); SL: 1.519 ± 0.11 (1.316–1.684); EL: 0.349 ± 0.03 (0.316–0.381); EW: 0.265 ± 0.03 (0.197–0.295); ML: 2.316 ± 0.1 (2.099–2.592); PSL: 0.325 ± 0.03 (0.289–0.368); SDL: 0.306 ± 0.024 (0.268–0.342); PL: 0.771 ± 0.08 (0.658–0.974); PPL: 0.398 ± 0.02 (0.342–0.447); PH: 0.532 ± 0.04 (0.474–0.632); PPH: 0.554 ± 0.05 (0.474–0.657); PNW: 1.226 ± 0.08 (1.079–1.368); PW: 0.409 ± 0.03 (0.342–0.487); PPW: 0.498 ± 0.04 (0.421–0.579); HI: 101.7 ± 2.3 (98.4–105.6); SI1: 77.9 ± 2.7 (73.9–82.6); SI2: 76.7 ± 3.7 (70.8–83.8); MI: 75.4 ± 2.3 (71.5–78.9); EI1: 75.8 ± 6.3 (62.5–84.6); EI2: 13.5 ± 0.7 (11.5–14.4); PI: 141.4 ± 7.9 (130.2–161.1); PPI: 72.8 ± 4.8 (65.1–83.3).

Color. Whole body uniformly brown to dark brown, sometimes mesonotum and propodeum with brighter brown to reddish brown pigmentation. Legs and antennae brown to dark brown, flagellum sometimes brighter than scape. Head. Square, nearly as long as wide, lateral surfaces below and above eyes gently convex, posterior edges convex, occipital margin of head concave. Anterior margin of the clypeus slightly convex and dentate on its central part. Eyes moderate, oval, 1.3 times as long as wide. Antennal scape short, in lateral view curved, 0.8 times as long as length of the head, in apex gradually widened, its base with distinct, triangular tooth, funiculus long. Surface of scape with very fine microreticulation, shiny, covered with thin, moderate dense, decumbent to erect setae. Mandibles rounded with thick sparse, longitudinal striae, shiny. Clypeus shiny with thick, longitudinal striae, area between striae shiny. Frontal carinae short, not extending beyond frontal lobes. Antennal fossa shallow, with sparse, thin and weak roundly curved striae, area between striae with sparse and fine microreticulation, shiny. Frontal lobes narrow, smooth with slight, dense longitudinal striation (Figures 7 and 8). Whole head shiny with very sparse and fine microreticulation, only single longitudinal wrinkles appear on the anterior part of frons center and malar area. The whole head surface covered with short, adpressed, and thick setae; frons and vertex with a few additional erect, thick setae; ventral surface of head with dense layer of thin, erect, straight setae. Mesosoma. Short, 1.8 times as long as wide; metanotal groove deep. Pronotum convex on sides. In lateral view promesonotum arched in profile, propodeum positioned lower than promesonotum and slightly arched, propodeum with very small tooth-like projections, its ventral surface slightly concave. Whole mesosoma shiny, with dense transverse striation. Sometimes dorsum of pronotum with reduced sculpture. Mesosoma dorsum with less than 10 thick, long, and straight setae. Petiole. In lateral view, with moderate peduncle, node high, with anterior face concave, posterior face straight and dorsum steep arched. Peduncle and petiolar node shiny, with sparse microreticulation, dorsum with sparser reticulation. Dorsal surface bearing sparse, ling, thick, erect setae. Postpetiole. In lateral view, regularly convex, apical half with gently convex sides, on the whole surface shiny, with sparse microreticulation, dorsum with microreticulation reduced. Dorsal surface bearing sparse, long, erect setae. Gaster. Gaster matt, with dense microreticulation, bearing erect, thin, pale setae.

Type Material
Salata and Borowiec (2019) - Lectotype (present designation) (w.): M. semirufus And. | v. concolor Em. | SANTSCHI det. 1926 || Crete | Rettimno |(Cecconi) || M. meridionalis | And. | concolor Em. || TYPE || Sammlung | Dr. F. Santschi | Kairouan || ANTWEB |CASENT0913219 ; Syntype (w): M. semirufus And. | v. concolor Em. | SANTSCHI det. 1926 || Crete | Rettimno | (Cecconi) || M. meridionalis| And. | concolor Em. || TYPE || Sammlung | Dr. F. Santschi | Kairouan || ANTWEB | CASENT0913220 (NHMB); Syntype (w): M. barbarus |semirufus | v. concolor Em. || Creta (Cecconi) | Kalives || concolor | cotype ||Syntypus | Messor barbarus |semirufus | ''var. concolor'' | des. EMERY, 1908 || MUSEO GENOVA | coll. C. Emery | (dono 1925) | ANTWEB |CASENT0904126.

References based on Global Ant Biodiversity Informatics

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 * Legakis Collection Database
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 * Pashaei Rad S., B. Taylor, R. Torabi, E. Aram, G. Abolfathi, R. Afshari, F. Borjali, M. Ghatei, F. Hediary, F. Jazini, V. Heidary Kiah, Z. Mahmoudi, F. Safariyan, and M. Seiri. 2018. Further records of ants (Hymenoptera: Formicidae) from Iran. Zoology in the Middle East 64(2): 145-159.
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 * Salata S., and L. Borowiec. 2019. Preliminary contributions toward a revision of Greek Messor Forel, 1890 (Hymenoptera: Formicidae). Turkish Journal of Zoology 43: 52-67.
 * Santschi, F.. "Revision des Messor du groupe instabilis Sm. (Hymenopt.)." Boletín de la Real Sociedad española de Historia natural (Madrid) 27 (1927): 225-250.
 * Tohmé, G., and H. Tohmé. "Les fourmis du genre Messor en Syrie. Position systématique. Description de quelques ailés et de formes nouvelles. Répartition géographique." Ecologia Mediterranea 7 (1) (1981): 139-153, fig. 1-22.
 * Wheeler W. M. and W. M. Mann. 1916. The ants of the Phillips Expedition to Palestine during 1914. Bulletin of the Museum of Comparative Zoology 60: 167-174.