Aphaenogaster crocea sicula

Found in clay soiled meadows and other open habitats.

Identification
A member of the Aphaenogaster subterranea-group.

Alicata and Schifani (2019) - Worker. The color pattern is unique among the sympatric species, having the head darker than mesosoma, both ferruginous, and the gaster very dark (somewhat resembling the Maghrebian Aphaenogaster strioloides). In addition, Aphaenogaster sicula presents a very reduced promesonotal suture (especially different in comparison to Aphaenogaster trinacriae) with a more convex mesonotum than Aphaenogaster fiorii, while still lacking the metanotal groove marked like in Aphaenogaster subterranea s. l. in lateral view). Moreover, Aphaenogaster sicula is less sculptured than most similar species (except for example the very different Aphaenogaster crocea lenis) and its head appears shiny if compared to that of Aphaenogaster trinacriae. It is also a relatively small species.

Male. Only some of the Aphaenogaster males present a mesosoma with an anterior gibbous part and a comparatively flat posterior part like Aphaenogaster sicula. Among the sympatric species that do so, Aphaenogaster splendida can be easily distinguished by different shape of the metathorax, forming a decisively slenderer area in front of the propodeum in lateral view (see Emery 1908, 1916). Aphaenogaster sardoa male (Santschi 1911) is larger, its metathorax does not form slenderer part in front of the propodeum, it possesses a visibly less gibbous anterior part and more abundant erect setae on the body. Aphaenogaster fiorii and Aphaenogaster trinacriae are the most similar, but do not possess the aforementioned slenderer part in front of the propodeum in the flatter part of the mesosoma. In addition, Aphaenogaster fiorii is much lighter in color and presents more developed and differently shaped tubercles on the propodeum, while Aphaenogaster trinacriae is distinguished by the well-developed enlarged flat areas on the sides of the propodeum (better observed in dorsal view). The shape of the mesosoma also distinctively separates Aphaenogaster sicula from the somewhat similar Maghrebian species: Aphaenogaster crocea, Aphaenogaster faureli, Aphaenogaster mauritanica, Aphaenogaster nadigi, Aphaenogaster strioloides, and Aphaenogaster theryi.

Queen. Among sympatric species the mesosoma shape in Aphaenogaster sicula is only similar to that of Aphaenogaster fiorii, Aphaenogaster trinacriae and Aphaenogaster subterranea s. l. However, Aphaenogaster fiorii is chromatically very different, and Aphaenogaster subterranea s. l. is also often darker. Moreover, Aphaenogaster sicula is unique for its short and thick spines. The scarcity of available information does not allow a proper comparison with the Maghrebian forms.

Distribution
Aphaenogaster sicula seems to inhabit the whole Sicilian territory where the required ecological conditions are met and is also present in a small area in the southern part of Calabria. Further investigation is probably needed to establish its northernmost range limit.

Distribution based on Regional Taxon Lists
Palaearctic Region: Italy, Malta, Montenegro.

Habitat
Alicata and Schifani (2019) - Aphaenogaster sicula inhabits clay soils, living in meadows most of the times, but also in garrigues or degraded Mediterranean maquis, and can also be found in Pinus afforestations at low altitudes. Nonetheless, it is generally associated with open habitats. It is collected between 35 m and 840 m.

Biology
Phenology. In captive colonies, sexuals began to leave the nest from the second week of July to the first week of August, but no attempt to form an actual nuptial flight was detected. In the wild it can be speculated that nuptial flights may start with the first relevant rains at the end of summer.

Conservation. Viable habitats for Aphaenogaster sicula seem to be abundant in its distribution range. Unless a massive change in land usage takes place, the species should not face particular threats. In addition, the data here presented may represent a significant underestimation of its distribution in Sicily. Monogynous (no more than one queen per colony detected in the wild).

Nomenclature

 *  sicula. Aphaenogaster crocea subsp. sicula Emery, 1908c: 331 (w.q.) ITALY. Combination in Aphaenogaster (Attomyrma): Emery, 1921f: 57. Raised to species: Schembri & Collingwood, 1981: 423. Material of the unavailable name subterraneosplendida referred here by Emery, 1908c: 331.

Worker
Measurements and indices (90 individuals, 14 localities): HL: 1.05 ± 0.04 (0.95–1.15); HW: 0.90 ± 0.05 (0.80–1.00); CI: 85.35 ± 2.30 (79.54–90.69); FW: 0.77 ± 0.04 (0.67–0.85); SL: 1.10 ± 0.04 (1.00–1.20); SI: 122.50 ± 3.43 (115.00–129.41); MW: 0.58 ± 0.03 (0.52–0.65); ML: 1.37 ± 0.06 (1.25 ± 1.50). Whole body ferruginous, yellowish in freshly emerged workers, except for gaster which is dark brown. Head darker, more brownish than mesosoma and legs. Head subrectangular, lateral margins under eyes slightly rounded, posterior margin of head slightly rounded. Anterior margin of clypeus gradually convex, mandibles rounded. Antennae with twelve segments, antennal club with four segments. Promesonotal suture only slightly marked, the two forming almost continuous dorsal profile in lateral view. In lateral view dorsal profile of metanotum is rounded, dorsal profile of propodeum mostly straight, spines variable, often slightly oriented upwards. Sculpture relatively weak and shiny aspect in general. Head finely reticulated with longitudinal striae mostly limited to lateral areas under eyes, sparsely present above eyes and variably on mandibles. Mesepisternum and propodeum reticulated with fine longitudinal striae, pronotum finely imbricate, gaster smooth, petiole and postpetiole finely imbricate to reticulate. Suberect and erect setae sparse all over head, decumbent setae on mandibles, adpressed setae on scapes and adpressed to subdecumbent setae on flagellomeres. Long setae extending down from clypeus. Erect setae all over dorsal surface of mesosoma, petiole and postpetiole, and all over gaster. Mostly adpressed, partly suberect setae on legs, with sparse erect setae on coxae and femora.

Queen
Measurements and indices (6 individuals, 5 localities): HL: 1.35 ± 0.40; HW: 1.30 ± 0.02; CI: 96.33 ± 1.55; FW: 1.11 ± 0.02; SL: 1.22 ± 0.02; SI: 93.60 ± 1.55; MW: 1.24 ± 0.02; ML: 2.30 ± 0.04. Whole body ferruginous, with darker areas on gaster. Head subrectangular, lateral surface below eyes rounded, posterior margin of head straight. Anterior margin of clypeus slightly convex, mandibles rounded. Antennae with twelve segments, antennal club with four segments. Pronotum rounded in dorsal view, propodeal spines horizontal and with wide base. Petiole with long peduncle and node convex on both sides, postpetiole with anterior concave side and posterior slightly convex side. Entire head, except clypeus and occipital margin, densely covered with longitudinal striae. Long and more marked striae are subparallel to each other. Between them, less marked striae can be found often crossing each other. Mesosoma mostly shiny, with horizontal striae appearing in proximity of sutures, across propodeum and posterior faces of petiole and postpetiole. Adpressed to decumbent setae on antennae, suberect to mostly erect setae on head, dorsal part of mesosoma, of petiole and postpetiole and all over gaster. Long setae extending down from clypeus. Adpressed to decumbent setae on legs.

Male
Measurements and indices (5 individuals, 1 locality): HL: 0.60 ± 0.00; HW: 0.63 ± 0.01; CI: 105.00 ± 1.83; FW: 0.39 ± 0.01; SL: 0.17 ± 0.00; SI: 27.78 ± 0.48; MW: 0.69 ± 0.01; ML: 1.38 ± 0.02. Whole body brown, head and thorax sometimes slightly darker than abdomen, appendages paler than rest of body. Head subtrapezoidal, occipital margin rounded, anterior margin of clypeus presenting small concavity, eyes large and oval. Antennae with thirteen segments, antennal club with five segments. Mesosoma elongated, with anterior gibbous part formed by prothorax, mesothorax and part of metathorax, and posterior part comparatively flat formed by part of metathorax and propodeum. Promesonotal suture well marked, pronotum and mesonotum convex in lateral view, rounded on side. Metathorax arched, consisting of subvertical and subhorizontal part. Subhorizontal part, in dorsal view, becomes very narrow in proximity of subvertical part. Propodeum not much thicker than horizontal part of metathorax in lateral view. Propodeal spines are absent and only represented by two tubercles. Petiole elongated, petiolar node and postpetiolar node rounded, both dorsally present shallow longitudinal suture in center. Petiole in dorsal view presents significantly enlarged area between node and articulation with propodeum. Scape very short, covered by rare decumbent setae, decumbent to subdecumbent setae also present on head, mesosoma and legs, few erect setae on mesosoma, coxae, petiole and postpetiole and suberect to erect setae on gaster. Head finely reticulated, rest of body smooth and shiny.

Type Material
LECTOTYPE (here designated): 1 worker (top specimen of three ergatoids on one pin), 8.XII.1877, Mt. Pellegrino, worker, A. crocea / sicula Emery (handwritten), Coll. C. Emery, Museo Genova ?, ANTWEB, CASENT0904177. LECTOTYPUS *des. Alicata & Schifani 2018, Aphaenogaster sicula det. Alicata & Schifani 2018 [M. Pellegrino (PA), Sicily, ]. PARALECTOTYPES: 2 ergatoids, same as lectotype on the same pin as the lectotype, plus PARALECTOTYPUS, 1 queen, A. crocea / sicula Emery, 8.XII.1877, Mt. Pellegrino, queen, Coll. C. Emery, MSNG PARALECTOTYPUS des. Alicata & Schifani 2018, Aphaenogaster sicula det. Alicata & Schifani 2018 [M. Pellegrino (PA), Sicily, MSNG]. 3 ergatoids, Aphaenogaster crocea sicula Emery, 8.XII.1877, Mt. Pellegrino, worker, Coll. A. Forel. PARALECTOTYPUS des. Alicata & Schifani 2018, Aphaenogaster sicula det. Alicata & Schifani 2018 [M. Pellegrino (PA), Sicily, ].