Aphaenogaster sicula Emery, 1908

Alicata, Antonio & Schifani, Enrico, 2019, Three endemic Aphaenogaster from the Siculo-Maltese archipelago and the Italian Peninsula: part of a hitherto unrecognized species group from the Maghreb? (Hymenoptera: Formicidae: Myrmicinae), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 59 (1), pp. 1-16 : 7-10

Aphaenogaster sicula Emery, 1908

Published records (excluding bibliographic checklists). As Aphaenogaster subterranea var. subterraneo-splendida in EMERY & FOREL (1879) (type material – examined, see EMERY 1908) and as A. crocea sicula in EMERY (1908) (type material – examined) and KUTTER (1927) (material examined).

Material under the name A. crocea sicula in BARONI URBANI (1964) belongs to A. subterranea ichnusa (material examined), those in BARONI URBANI (1968) ( material examined) and as A. sicula in SCHEMBRI & COLLINGWOOD (1981) (material examined) belong to A. fiorii stat. nov., those in SCUPOLA (2009) (material examined) and LI VIGNI (2014) (pictures examined) belong to A. trinacriae sp. nov.

Material published in PETROV (2000) could not be examined, but was most likely misidentified ( KARAMAN 2011).

Type material examined. LECTOTYPE (here designated): 1 ☿ (top specimen of three☿☿ on one pin), 8.XII.1877 / Mt.Pellegrino /☿ // 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, MSNG]. PARALECTOTYPES: 2 ☿☿, same as lectotype on the same pin as the lectotype, plus // PARALECTOTYPUS //. 1 ♀, A. crocea / sicula Emery // 8.XII.1877 / Mt. Pellegrino / ♀ // Coll. C. Emery / Museo Genova // PARALECTOTYPUS / des. Alicata & Schifani 2018 // Aphaenogaster sicula det. Alicata & Schifani 2018 [M. Pellegrino (PA), Sicily, MSNG]. 3 ☿☿, A. crocea sicula Emery // 8.XII.1877 / Mt. Pellegrino / ☿ // Coll. A. Forel // PARALECTOTYPUS / des. Alicata & Schifani 2018 // Aphaenogaster sicula det. Alicata & Schifani 2018 [M. Pellegrino (PA), Sicily, MHNG].

Additional material examined. ITALY: SICILY: Segesta (AG), Sicily, Italy, 1927, leg. H.Kutter ( KUTTER 1927) ( MZLS); Pendici di M.Altesina, Nicosia (EN), Sicily, Italy, 37°40 ′ 22.19 ″ N, 14°18 ′ 38.62 ″ E, 840 m, meadow, 30.viii.1993, leg. A. Alicata ( AACI); Colle Vampolieri, Acicatena (CT), Sicily, Italy, 37°34 ′ 21.1 ″ N, 15°09 ′ 19.4 ″ E, 140 m, 11.xi.1993, leg. A. Alicata ( AACI, MSNM); Lago Arancio, S. Margherita Belice (AG), Sicily, Italy, 37°38 ′ 43.8 ″ N 13°03 ′ 49.9 ″ E, 185 m, meadow near the shore, 11.xii.1993, leg. A. Alicata ( AACI); Misilifurmi, Sciacca (AG), Sicily, Italy, meadow, 37°36 ′ 04.4 ″ N, 13°02 ′ 44.8 ″ E, 80 m, 11.xii.1993, leg. A. Alicata ( AACI); Ficuzza (PA), Sicily, Italy, 37°53 ′ 6.23 ″ N, 13°22 ′ 41.29 ″ E, 650 m, meadow, 18.ii.1994, leg.A.Alicata ( AACI); Baida, Scopello (TP), Sicily, Italy, 38°02 ′ 55.3 ″ N, 12°47 ′ 46.4 ″ E, 390 m, meadow, 1.iii.1994, leg. A.Alicata ( AACI); C.da Catuffo, M.Sparagio,Custonaci (TP), Sicily,Italy, 38°02 ′ 33.2 ″ N, 12°45 ′ 12.9 ″ E, 340 m, meadow, 02.iii.1994, leg.A.Alicata ( AACI); P.zo Giacolamaro, M. Sparagio, Custonaci (TP), Sicily, Italy, 38°3 ′ 18.70 ″ N, 12°44 ′ 25.08 ″ E, 660 m, meadow, 02.iii.1994, leg.A.Alicata ( AACI); SS118 Corleone-Marineo km 26 (PA),Sicily, Italy, 37°51 ′ 08.4 ″ N, 13°18 ′ 50.7 ″ E, 490 m, meadow, 19.ii.1994, leg.A.Alicata ( AACI); Gualtieri Sicaminò (ME), Sicily, Italy, 38°9 ′ 27.26 ″ N, 15°19 ′ 27.83 ″ E, 285 m, meadow, 24.xi.1994, leg. A. Alicata ( AACI); Lago di Piana, Piana degli Albanesi (PA), Sicily, Italy, 38°3 ′ 18.70 ″ N 12°44 ′ 25.08 ″ E, 600 m, meadow near the shores, 2.iii1994, leg.A.Alicata ( AACI); Pendici di M. Scalpello, Catenanuova (EN), Sicily, Italy, 37°33 ′ 5.35 ″ N, 14°40 ′ 54.84 ″ E, 840 m, meadow, 31.iii.1999, leg. A. Alicata ( AACI); Monte Pellegrino (PA), Sicily, Italy, 38°10 ′ 22.4 ″ N, 13°21 ′ 03.5 ″ E, 395 m, Pinus reforestation, 12.iv.2016, leg. E. Schifani ( ESPI); Gole del Drago (PA), Sicily, Italy, 37°51 ′ 57.1 ″ N, 13°18 ′ 03.1 ″ E, 470 m, meadow near a degraded low Mediterranean maquis, 24.iv.2016, leg. E. Schifani ( ESPI); Erice (TP), Sicily, Italy, 38°02 ′ 24.8 ″ N, 12°35 ′ 09.2 ″ E, 700 m, meadow surrounded by Quercus ilex forest and Pinus reforestation, 04.xi.2016, leg. E. Schifani ( ESPI); Lago di Prizzi (PA), Sicily, Italy, 37°44 ′ 02.7 ″ N, 13°24 ′ 28.2 ″ E, 650 m, meadow, 22.v.2016, leg. E. Schifani ( ESPI); Grotta di S. Teodoro (ME), Sicily, Italy, 38°03 ′ 00.1 ″ N, 14°35 ′ 29.8 ″ E, 135 m, olive crops, xii.2017, leg. E. Genduso ( ESPI). ITALIAN PENINSULA: Platì (RC), Italy, 38°13 ′ 05.7 ″ N, 16°02 ′ 54.5 ″ E, 280 m, meadow, 16.xi.1993, leg.A.Alicata ( AACI, MSNM); Africo Nuovo (RC), Italy, 38°2 ′ 52.42 ″ N, 16°8 ′ 13.52 ″ E, 20 m,meadow, 17.xi.1993, leg.A.Alicata ( AACI); F.mara S.Venere,Samo (RC), Italy, 38°4 ′ 12.57 ″ N, 16°4 ′ 42.10 ″ E, 80 m, meadow, 14.iv.1997, leg. A.Alicata ( AACI); P.te Torr.S.Venere,S. Luca (RC), Italy, 38°08 ′ 42.9 ″ N, 16°04 ′ 43.8 ″ E, 80 m, meadow, 20.xi.1993, 23.i.2003,leg.A.Alicata ( AACI, MSNM). Bova (RC), Italy, 37°57 ′ 51.9 ″ N 15°55 ′ 21.5 ″ E, 380 m, meadow, 13.xi.2016, leg. E. Schifani ( ESPI).

Worker redescription ( Figs 5, 6, 10 , 14, 15 ). 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.

Male description ( Figs 22, 23, 27 , 31, 32 ). 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.

Queen redescription ( Figs 37, 38, 42 ). 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.

Systematic position. Aphaenogaster sicula first appears as Aphaenogaster subterranea var. subterraneo-splendida in EMERY & FOREL (1879), but this is a nomen nudum ( EMERY 1908). Consequently, it was then described by EMERY (1908) who considered it a subspecies of A. crocea . Aphaenogaster sicula was finally elevated to species-rank by SCHEMBRI & COLLINGWOOD (1981) on the basis of its worker morphology. However, SCHEMBRI & COLLINGWOOD (1981) based their judgment exclusively on misidentified material of A. fiorii stat. nov. from Malta. Despite this fact, due to the degree of morphological differences from any other congeneric species, relevant in all three castes (see also comparative diagnosis), we surely agree to consider it a bona species.

Comparative diagnosis. 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 A. strioloides ). In addition, A. sicula presents a very reduced promesonotal suture (especially different in comparison to A. trinacriae sp. nov.) with a more convex mesonotum than A. fiorii stat. nov., while still lacking the metanotal groove marked like in A. subterranea s. l. in lateral view ( Figs 12 ‒ 19 ). Moreover, A. sicula is less sculptured than most similar species (except for example the very different A. crocea lenis Santschi, 1911 ) and its head appears shiny if compared to that of A. trinacriae sp. nov. 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 A. sicula . Among the sympatric species that do so, A. 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 stat. nov. and A. trinacriae sp. nov. 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, A. fiorii stat. nov. is much lighter in color and presents more developed and differently shaped tubercles on the propodeum, while A. trinacriae sp. nov. 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 A. sicula from the somewhat similar Maghrebian species: A. crocea (see CAGNIANT 1966), A. faureli (see CAGNIANT 1969), A. mauritanica (see SANTSCHI 1932, CAGNIANT 1987), A. nadigi (see CAGNIANT 1987), A. strioloides (see SANTSCHI 1932), and A. theryi (see CAGNIANT 1986, 1996).

Queen. Among sympatric species the mesosoma shape in A. sicula is only similar to that of A. fiorii stat. nov., A. trinacriae sp. nov. and A. subterranea s. l. However, A. fiorii stat. nov. is chromatically very different, and A. subterranea s. l. is also often darker. Moreover, A. 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 and biogeographical remarks ( Fig. 45 ). 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. Land connections between Calabria and Sicily occurred relatively frequently during the later stages of the Pleistocene ( BONFIGLIO et al. 2002), and a Siculo-South Calabrian chorotype was established for the Italian fauna (STOCH & VIGNA TAGLIANTI 2006). Dispersion of A. sicula most likely occurred from Sicily to Calabria. Its alleged presence in the Maltese islands was based exclusively on misidentified specimens of A. fiorii stat. nov. as already mentioned. Finally, BARONI URBANI (1971) interpreted BERNARD’ s (1958) record of A. crocea for Lampedusa as A. crocea sicula but MEI (1995) considered the original record by Bernard erroneous and based on a misidentification of A. sardoa . More recent collecting efforts only reinforce Mei’s hypothesis (ES, unpublished data; A. Scupola, unpublished data). A particularly aberrant record was published by PETROV (2000) for Montenegro (without any more precise locality), but it was most likely a result of misidentification ( KARAMAN 2011).

Ecology. 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.

Conservation. Viable habitats for A. 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 ( Fig. 45 ) may represent a significant underestimation of its distribution in Sicily.

Biology. Monogynous (no more than one queen per colony detected in the wild).

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.

Figures

Fig 45. Distribution of Aphaenogaster sicula Emery, 1908.

Figs 3–11. Workers in dorsal, lateral and head view (scale bar: 0.50 mm): 3, 4, 9 – Aphaenogaster fiorii Emery, 1915, stat. nov., non-type worker from Malta; 5, 6, 10 – A. sicula Emery, 1908, non-type worker from M. Pellegrino, Sicily, Italy (type locality); 7, 8, 11 – A. trinacriae sp. nov., holotype worker AACI-ANTP001/1 from M. Sparagio, Sicily, Italy. Photos by Enrico Schifani.

Figs 12–19.Workers mesosomata in dorsal and lateral view, which allows the observation of several diagnostic features of each species (some are highlighted by arrows). Scale bar: 0.50 mm. 12, 13 – Aphaenogaster fiorii Emery, 1915, stat. nov., non-type worker from Malta; arrows pointing at the peculiar shape of the mesonotum. 14, 15 – A. sicula Emery, 1908, non-type worker from M. Pellegrino (PA), Sicily, Italy (type locality). 16, 17 – A. trinacriae sp. nov., non-type worker from Bosco della Ficuzza (PA), Sicily, Italy; arrows pointing at the characteristic promesonotal suture.18–19 – Aphaenogaster subterranea ichnusa Santschi, 1925: 18 – non-type worker from M. Petroso (PA), Sicily, Italy; 19 – non-type worker from Bosco della Ficuzza (PA), Sicily, Italy; arrow pointing at the characteristic profile corresponding to the marked metanotal groove. Photos by Enrico Schifani.

Figs 20–28. Males in dorsal, lateral (scale bar: 0.50 mm) and head view (scale bar: 0.25 mm). 20, 21, 26 – Aphaenogaster fiorii Emery, 1915, stat. nov., non-type male from Bosco di Aci S. Antonio, Sicily, Italy. 22, 23, 27 – A. sicula Emery, 1908, non-type male from Ficuzza, Sicily, Italy. 24, 25, 28 – A. trinacriae sp. nov., paratype male AACI-ANTP003/1 from M. Sparagio, Sicily, Italy. Photos by Enrico Schifani.

Figs 29‒34. Males genitals, view of the inner face of lacinia and volsella (left) and of the subgenital plate (right). 29, 30 – Aphaenogaster fiorii Emery, 1915, stat. nov. 31, 32 – A. sicula Emery, 1908. 33, 34 – A. trinacriae sp. nov. Drawings by Antonio Alicata.

Fig 35‒43. Queens in dorsal, lateral view (scale bar: 1.00 mm), detail of spines in lateral view (no scale bar) and head view (scale bar: 0.50 mm). 35, 36, 41 – Aphaenogaster fiorii Emery, 1915, stat. nov., non-type queen from Bosco di Aci S. Antonio, Sicily, Italy. 37, 38, 42 – A. sicula Emery, 1908, non-type queen from Contrada Catuffo, pendici M. Sparagio, Sicily, Italy. 39, 40, 43 – A. trinacriae sp. nov., paratype queen AACI-ANTP002/1 from M. Sparagio, Sicily, Italy. Photos by Enrico Schifani.