Temnothorax estel

Nests of this species were found at high altitude in rock crevices and once under a plain stone, and populations were located from stony open habitats to semi-open pine forests. All colonies were monogynous. Nest densities were always low. Two colonies kept in an artificial nest were fed with insects and nectar and produced reproductive individuals in early July. The elongated head may be an adaptation to move into rock crevices and nest in narrow spaces.

Identification
Characterized within the Iberian sordidulus species-complex by being bicolored, with yellowish mesosoma and darker head dorsum; sculpture of frons entirely reticulated; head elongate (mean HL/HWb 1.275); metanotal groove inconspicuous to very shallow; and with the longest propodeal spines of the complex (mean SPST/CS 0.313).

Temnothorax estel is easily distinguished from any other taxa of the Iberian sordidulus species-complex by the unique combination of bicolored body, long head (mean HL/HWb 1.275), inconspicuous to poorly-developed metanotal groove (mean MGr/CS 0.297%) and longest propodeal spines of the complex (mean SPST/CS 0.313).

The most closely related species to T. estel is Temnothorax tergestinus, from Central Europe. The first has much longer head (mean HL/HWb 1.252 vs. 1.206), narrower frontal carina (mean FRS/CS 0.343 vs. 0.361), longer scape (mean SL/CS 0.826 vs. 0.799), inconspicuous to poorly-developed metanotal groove (vs. poorly to well-developed metanotal groove in T. tergestinus) and longer and more diverging propodeal spines (mean SPST/CS 0.313 vs. 0.276; SPWI/CS 0.342 vs. 0.333). Both species exhibit the same coloration pattern, but T. tergestinus can also show extreme dark forms (Csősz et al. 2015; Borowiec & Salata 2018). Temnothorax tergestinus has a wide Palearctic distribution from Bulgaria to France, but has not been yet recorded from Iberia. It is unknown whether a contact zone between T. estel and T. tergestinus could exist somewhere in North Iberia or South France.

MGr is probably one of the best discriminant characters between T. estel and T. tergestinus, but it has not been measured for the latter species in this paper. Queens of both taxa appear very similar, and the only available queen of T. estel does not allow a safe separation with the queens of T. tergestinus. Males of the sordidulus species-complex are largely unknown and rarely described, since the external morphology is very variable within the same nest and the study of the genitalia is not routinely used in the genus.

Distribution based on Regional Taxon Lists
Palaearctic Region: Iberian Peninsula, Spain.

Nomenclature

 * . Temnothorax estel González, 2021: 150, figs. 2B, 3, 5, 6B (w.q.) SPAIN.

Type Material

 * Holotype worker: Spain, Serra d’Aitana (Alacant), 20.VI.2020, 38°39’05.6”N 0°14’13.7”W, 1282 m (MCNB code MZB 2021-0727).
 * Paratypes: 4 workers, same nest and date as holotype (MCNB codes MZB 2021-0728, MZB 2021-0729, MZB 2021-0730 and MZB 2021-0731); 5 workers, same nest and date as holotype (will be deposited in MNHN); 5 workers, same nest and date as holotype (will be deposited in CASC).