Aphaenogaster trinacriae, Alicata & Schifani, 2019

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 : 10-13

Aphaenogaster trinacriae sp. nov.

Published records (excluding catalogues). As Aphaenogaster sp. n. in ALICATA (1999) (type material and other examined material).

Misidentified as A. sicula in SCUPOLA (2009) (material examined), LI VIGNI (2014) (pictures examined), LEBAS et al. (2016) (pictures examined) and as A. splendida in SCUPOLA (2017) (material examined).

Type material. HOLOTYPE: 1 ☿, Aphaenogaster trinacriae Alicata & Schifani // Italy – Sicilia – Custonaci TP / M. Sparagio, P.zzo Giacolamaro / 38°3’56.42”N 12°46’43.14”E 700 m / Alicata leg. – 2.III.1994 / Q. ilex forest – AACI-ANTP001 /1 // HOLOTYPUS / des. Alicata & Schifani // A.trinacriae det. Alicata & Schifani 2018 ( MSNG). PARATYPES: ITALY: SICILY: 2 ☿☿, same as holotype except AACI-ANTP001/3 // PARATYPUS / des.Alicata & Schifani ( MSNG); 3☿☿, same as holotype except 22.XI.1996 / AACI-ANTP002/2 PARATYPUS / des. Alicata & Schifani ( MSNG); 1 ♂, same as holotype except 8.VII.1997 / from rearing – AACI-ANTP003/1 PARATYPUS / des.Alicata & Schifani (in photo, MSNG); 1 ♂, same as holotype except 8.VII.1997 / from rearing – AACI-ANTP003/2 PARATYPUS / des. Alicata & Schifani ( MSNG); 1 ♀, same as holotype except AACI-ANTP001/2 // PARATYPUS / des. Alicata & Schifani ( MSNG); 1 ♀, same as holotype except 22.XI.1996 / AACI-ANTP002/1 PARATYPUS / des. Alicata & Schifani ( MSNG); 4 ☿☿, Erice 10.xii.1993 / leg. Alicata // PARATYPUS / des. Alicata & Schifani // A.trinacriae det.Alicata & Schifani 2018 ( MSNM); 8☿☿ and 1 ♀, Italy – Sicilia – Erice TP / M. Erice m 600 / mixed forest / 10.XII.1993 leg.Alicata // PARATYPUS / des.Alicata & Schifani // A. trinacriae det. Alicata & Schifani 2018 ( AACI); 2 ♂♂, Italy – Sicilia – Erice TP / M. Erice m 600 / from rearing / 14.VII.1997 leg.Alicata // PARATYPUS / des. Alicata & Schifani // A. trinacriae det. Alicata & Schifani 2018 ( AACI). Additional material examined. ITALY: SICILY: Monte S. Caterina vers. W, Favignana (TP), Sicily, Italy, 37°56 ′ 20 ″ N, 12°18 ′ 29 ″ E, 110 m, Mediterranean maquis, 2.v.1991, leg. R. Poggi ( MSNG); M. Erice, Erice (TP), Sicily, Italy, 38°2 ′ 14.52 ″ N, 12°35 ′ 42.99 ″ E, from 450 to 600 m, mixed forest and Pinus reforestation, 10.xii.1993, 21.xi.1996, 6.xii.1996, leg.A.Alicata ( AACI, MSNM); M.Altesina, Nicosia (EN), Sicily, Italy, 37°40 ′ 18.49 ″ N, 14°18 ′ 30.34 ″ E, 915 m, Quercus ilex forest, 30.viii.1994, leg. A. Alicata ( AACI); Bosco di Gibilmanna, Gibilmanna (PA), Sicily, Italy, deciduous forest of the Quercus pubescens group, 28.v.1996, leg. A. Alicata ( AACI); V.ne Fanuso, Bosco della Ficuzza (PA), Sicily, Italy, mixed forest, 24.v.1996, 18.iii.1997, 29.iii.1997, leg. A. Alicata ( AACI); C.da Pintorna, Geraci Siculo (PA), Sicily, Italy, Quercus suber forest, 30.v.1996, leg. A. Alicata ( AACI); C.da Albinelli, Sortino (SR), Sicily, Italy, 37°12 ′ 16.99 ″ N, 15°4 ′ 51.15 ″ E, 365 m, Quercus suber forest, 3.x.1996, leg.A.Alicata ( AACI); Baida, Scopello (TP), Sicily, Italy, 38° 2 ′ 57.11 ″ N, 12°47 ′ 44.97 ″ E, 480 m, Mediterranean maquis, 20.xi.1996, leg. A. Alicata ( AACI); Bosco Scorace, Castellammare del Golfo (TP), Sicily, Italy, Quercus ilex forest, 15.xii.1997, leg.A.Alicata ( AACI); Pizzo Giacolamaro, M. Sparagio, Custonaci (TP), Sicily, Italy, 38°3 ′ 56.42 ″ N, 12°46 ′ 43.14 ″ E, 685 m, Quercus ilex forest, 21.xi.1997, leg. A. Alicata ( AACI); Monte Sparagio, Custonaci (TP), Sicily, Italy, 38°3 ′ 56.42 ″ N 12°46 ′ 43.14 ″ E, 550 m, Quercus ilex forest, 21.xi.1997, leg. A. Alicata ( AACI); Pizzo Niviere, M. Inici, Castellammare del Golfo (TP), Sicily, Italy, 38°0 ′ 22.88 ″ N, 12°51 ′ 13.22 ″ E, 1,000 m, Quercus ilex forest, 22.xi.1997, leg.A.Alicata ( AACI); V.ne Schiavo, Bosco del Cappelliere (PA), deciduous forest of the Quercus pubescens group, 19.iii.1997, leg. A. Alicata ( AACI); Bosco di Alcamo, Alcamo (TP), Sicily, Italy, 37°57 ′ 24.56 ″ N, 12°57 ′ 47.58 ″ E, 770 m, mixed forest, 26.vi.1997, leg.A. Alicata ( AACI); Alpe Ramosa, Bosco della Ficuzza (PA), Sicily, Italy, Quercus ilex forest, 28.vi.1997, leg. A. Alicata ( AACI); Pulpito del Re, Bosco della Ficuzza (PA), Sicily, Italy, Quercus suber forest, 28.vi.1997, leg. A. Alicata ( AACI); Lago Gammauta, Palazzo Adriano (PA), Sicily, Italy, 37°41 ′ 5.27 ″ N, 13°20 ′ 53.66 ″ E, 500 m, mixed forest, 10.vii.1997, leg. A. Alicata ( AACI); Santuario di Rifesi, Burgio (AG), Sicily, Italy, deciduous forest of the Quercus pubescens group, 37°36 ′ 33.96 ″ N, 13°20 ′ 46.08 ″ E, 775 m, 11.vii.1997, leg. A. Alicata ( AACI); Serra del Biondo, Burgio (AG), Sicily, Italy, 37°37 ′ 22.95 ″ N, 13°19 ′ 53.82 ″ E, 1,070 m, Pinus reforestation, 11.vii.1997, leg. A. Alicata ( AACI); Valle del Sosio, Palazzo Adriano (PA), Sicily, Italy, 37°40 ′ 49.61 ″ N, 13°20 ′ 48.47 ″ E, 480 m, Quercus ilex forest, 27.vii.1997, leg.A.Alicata ( AACI); C.da Sugherita, M. Sambughetti-Campanito, Nicosia (EN), Sicily, Italy, Quercus suber forest, 29.viii.1997, leg. A. Alicata ( AACI); Bosco Scorace, Castellammare del Golfo (TP), Sicily, Italy, 37°59 ′ 14.51 ″ N, 12°45 ′ 31.62 ″ E, 385 m, Quercus ilex forest, 15.xii.1997, leg. A. Alicata ( AACI); P.lla Manderini, Geraci Siculo (PA), Sicily, Italy, 1,260 m, deciduous forest of the Quercus pubescens group, 24.ix.1998, leg. A. Alicata ( AACI); T.rre Montaspro, Isnello (PA), Sicily, Italy, 870 m, Quercus ilex forest, 02.x.1998, leg. A. Alicata ( AACI); V.ne Zucchi, Isnello (PA), Sicily, Italy, 985 m, Quercus ilex forest, 02.x.1998, leg. A. Alicata ( AACI); Piano Zucchi, Isnello (PA), Sicily, Italy, 1,070 m, Quercus ilex forest, 02.x.1998, leg. A. Alicata ( AACI); Vallone Moscasanti, R.N. O. Grotta del Monello (SR), Sicily, Italy, 37°0 ′ 59.00 ″ N, 15°9 ′ 44.20 ″ E, 130 m, mixed forest, pitfall traps, 21.x.2004, leg. A. Alicata ( AACI); Torretta Torre, Bosco della Ficuzza (PA), Sicily, x.2005, Malaise traps, leg. A. Gatto, sub A. splendida ( SCUPOLA 2017; the cited worker was not found) ( MSNM); Bosco Scalia (PA), Sicily, 38°01 ′ 39.9 ″ N, 13°12 ′ 46.0 ″ E, 815 m, Quercus ilex forest, 08.iv.2016, leg. E. Schifani ( ESPI); Bosco della Ficuzza (PA), Sicily, 37°51 ′ 46.2 ″ N, 13°23 ′ 09.2 ″ E, 980 m, deciduous forest of the Quercus pubescens group, 23.vii.2016, leg. E. Schifani ( ESPI); Bosco della Ficuzza (PA), Sicily, 37°52 ′ 29.8 ″ N, 13°23 ′ 54.3 ″ E, 855 m, Quercus suber forest, 02.xii.2016, leg. E. Schifani ( ESPI); Erice (TP), Sicily, 38°02 ′ 23.8 ″ N, 12°35 ′ 09.3 ″ E, Quercus ilex forest, 710 m, 04.xi.2016, leg. E. Schifani ( ESPI); Bosco del Cappelliere (PA), Sicily, 37°55 ′ 30.0 ″ N, 13°23 ′ 18.0 ″ E, 520 m, 27.v.2017, leg. R. Viviano ( ESPI); Bosco della Ficuzza (PA), Sicily, 37°52 ′ 03 ″ N, 13°23 ′ 44 ″ E, 960 m, 1.viii.2017, leg. E. Nalini ( ESPI, MSNM).

Worker description ( Figs 7, 8, 11 , 16, 17 ). Measurements and indices (holotype worker): HL: 1.25; HW: 1.07; CI: 85.60; FW: 0.92; SL: 1.22; SI: 114.01; MW: 0.7; ML: 1.65: Measurements and indices (89 individuals, 14 localities; including holotype): HL: 1.16 ± 0.05 (0.97–1.27); HW: 1.01 ± 0.07 (0.77–1.17); CI: 87.14 ± 2.81 (79.48–92.15); FW: 0.87 ± 0.06 (0.70–1.00); SL: 1.17 ± 0.04 (1.05–1.27); SI: 115.59 ± 5.24 (106.38–135.48); MW: 0.64 ± 0.04 (0.52 ± 0.75); ML: 1.52 ± 0.08 (1.27–1.70). Whole body ferruginous (yellowish in freshly emerged workers), except for dark gaster. Central area of frons, scapi and femora are in some cases also darker than rest of head. Head subrectangular, lateral margins under eyes slightly rounded, posterior margin of head straight. Anterior margin of clypeus gradually convex, mandibles rounded. Antennae with twelve segments, antennal club with four segments. Promesonotal suture well-marked, creating clear discontinuity of dorsal profile in lateral view. In lateral view, dorsal profile of metanotum is rounded, dorsal profile of propodeum mostly straight, spines are variable in size and orientation, but are often horizontal. Sculpture relatively well developed in general. Head reticulated, with longitudinal striae almost reaching occiput, strongly developed especially under and around eyes, and present 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 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 24, 25, 28 , 33, 34 ). Measurements and indices (5 individuals, 1 locality): HL: 0.72 ± 0.02; HL: 0.72 ± 0.03; CI: 99.35 ± 1.44; FW: 0.48 ± 0.01; SL: 0.23 ± 0.01; SI: 32.65 ± 1.92; MW: 0.91 ± 0.09; ML: 1.73 ± 0.10. Whole body brown, 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, bearing two particularly enlarged flat areas on its sides (better observed in dorsal view). Propodeal spines are absent and only represented by two tubercles. Petiole elongated, petiolar node and postpetiolar node rounded, both dorsally presenting shallow longitudinal suture in center. Scape very short, covered by rare decumbent setae, decumbent to subdecumbent setae also present on head, mesosoma and legs, a few erect setae on mesosoma, coxae, petiole and postpetiole, suberect to erect setae on gaster. Head finely reticulated, rest of body smooth and shiny.

Queen description ( Figs 39, 40, 43 ). Measurements and indices (4 individuals, 3 localities): HW: 1.36 ± 0.01; HL: 1.29 ± 0.02; CI: 94.52 ± 0.01; FW: 1.12 ± 0.00; SL: 1.23 ± 0.01; SI: 95.18 ± 1.03; MW: 1.25 ± 0.03; ML: 2.36 ± 0.04. Whole body ferruginous, some lighter bands 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 slightly tending upwards and slender. 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.

Comparative diagnosis. Worker. Aphaenogaster trinacriae sp. nov. is characterized by ferruginous color of the body except for the very dark gaster and potential presence of dark area on the frons. Among the sympatric species this pattern can only be confused with some individuals of A. subterranea ichnusa or A. sicula . Aphaenogaster subterranea ichnusa can be easily distinguished by the marked metanotal groove in lateral view, less sculptured pronotum and different shape of the mesonotum. Aphaenogaster sicula tends to have darker head compared to the thorax and it is overall much less sculptured. Moreover, it presents a very reduced promesonotal suture, which on the contrary is very well marked in A. trinacriae sp. nov. The shape of the mesonotum and its sculpture easily separate A. trinacriae from any other similar Maghrebian congeneric species.

Male. Only some of the Aphaenogaster males present mesosoma with an anterior gibbous part and a comparatively flat posterior part like A. trinacriae sp. nov. 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 a slenderer part in front of the propodeum, it possesses a visibly less gibbous anterior part and much more abundant erect setae on the body. Aphaenogaster fiorii stat. nov. and A. sicula are the most similar, but do not possess the well developed enlarged flat areas on the sides of the propodeum (better observed in dorsal view). In addition, A. fiorii stat. nov. is much lighter and presents more developed and differently shaped tubercles on the propodeum. The shape of the mesosoma also distinctively separates A. trinacriae sp. nov. 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), A. theryi (see CAGNIANT 1986, 1996).

Queen. Among sympatric species the mesosoma shape is only similar to that of A. fiorii stat. nov., A. sicula and A. subterranea s. l. However, A. fiorii stat. nov. is chromatically very different, and both A. fiorii stat. nov. and A. sicula possess thicker spines. Aphaenogaster subterranea s. l. appears to be very similar but it is usually darker and possesses more rectangular head with more parallel sides in frontal view. The scarcity of available information does not allow a proper comparison with the Maghrebian forms.

Etymology. Trinacria is the ancient Greek name of Sicily; noun in genitive case standing in apposition.

Distribution and biogeographical remarks ( Fig. 46 ). Aphaenogaster trinacriae sp. nov. has the smallest distribution range of the three species, being exclusively limited to Sicily, where it is most abundant in its Western regions and completely absent in its North Eastern regions: in Etna, Nebrodi and Peloritani mountains the same habitats are occupied only by the ecologically similar A. subterranea ichnusa , and very rarely by A. fiorii stat. nov. Aphaenogaster trinacriae sp. nov. was also found in Favignana, a sedimentary island belonging to the Egadi Islands, which is about 7 km distant from the Western Sicilian coast and was alternately connected by land to Sicily in the past ( AGNESI et al. 1993).

Ecology. This species was mostly collected in natural Quercus forest but occasionally also in some artificial Pinus forest. All sites were either fully established forest or degraded forest. Altitude between 110 m and 1,260 m. Aphaenogaster trinacriae sp. nov. partly shares its distribution with that of A. subterranea ichnusa , whose ecology requirements are seemingly vastly overlapping ( SCHIFANI & ALICATA 2018), therefore competition between these two may be expected to be significant. On the contrary, A. subterranea s. str. is found at higher altitudes and/or in different habitats in Sicily ( SCHIFANI & ALICATA 2018). Aphaenogaster trinacriae was reported removing elaiosomes from seeds of Euphorbia characias ( LI VIGNI 2014, sub A. sicula ).

Conservation. Aphaenogaster trinacriae sp. nov. appears to have a well-defined habitat specificity mainly linked to thermophilous broad-leaved forests. Its abundance within the relatively small distribution range must have been severely reduced due to the very important deforestation that occurred in the past ( LA MANTIA 2009). Many sites in which the species is found are habitat patches likely too distant from each other to allow the species dispersal from one patch to another, resulting in presumably complete isolation of these populations.Although reforestation projects have increased the forested surface in Sicily, they may have not necessarily helped the species to recover the lost habitats. Aphaenogaster trinacriae sp. nov. has never been found in Eucalyptus reforestations, and reforestation patches of other kind may sometimes be too isolated to be colonized. It would be worth investigating if the abundant presence of A. subterranea ichnusa in some isolated reforested areas, in which A. trinacriae sp. nov. is absent despite seemingly adequate ecological conditions, is due to the lower dispersal capacity of the latter or unintentional introductions of the former.

Biology. Monogynous (no more than one queen per colony detected in the wild, attempts to found colonies in captivity with multiple queens only resulted in monogynous colonies).

Phenology. Winged sexuals were collected in nests in Bosco della Ficuzza (PA) during the last week of July and in C. da Sugherita, M. Sambughetti-Campanito (EN) in August. 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 ( ALICATA 1999). In the wild, it can be speculated that nuptial flights may start with the first relevant rains at the end of summer.

Myrmecophiles. Six individuals of Scydmaenus rufus Müller & Kunze, 1822 ( Staphylinidae , Scydmaeninae ) were collected inside a nest of A. trinacriae sp. nov. in Bosco della Ficuzza (PA) during December. Several associations between staphylinids of the subfamily Scydmaeninae Leach, 1815 and ants are known (O’KEEFE 2000), however most of them are probably facultative ( PARKER 2016).

Figures

Fig 46. Distribution of Aphaenogaster trinacriae sp. nov.

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.