Aphaenogaster fiorii Emery, 1915

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 : 3-6

Aphaenogaster fiorii Emery, 1915 stat. nov.

Published records (excluding bibliographic checklists). As A. gibbosa fiorii in EMERY (1915) (type material – examined) and as A. fiorii in ALICATA (1999).

Misidentified as A. crocea sicula in BARONI URBANI (1968) (material examined), as A. sicula in SCHEMBRI & COLLINGWOOD (1981) (material examined).

Material published by GRANDI (1935) could not be examined.

Type material examined. LECTOTYPE (here designated): 1 ☿, Sicilia / Nicolosi / 24.IV.’912 / leg. A. Fiori // Aphaen. gibbosa fiorii Emery (handwritten) // LECTOTYPUS / des. Alicata & Schifani 2018 // Coll. C. Emery / Museo Genova //ANTWEB / CASENT0904175 // Aphaenogaster fiorii / det. Alicata & Schifani 2018 [Nicolosi (CT) – MSNG]. PARALECTOTYPE: 1 ☿, Sicilia / Nicolosi / 24.IV.’912 / leg. A.Fiori // PARALECTOTYPUS / des. Alicata & Schifani 2018 // Coll. C. Emery / Museo Genova // Aphaenogaster fiorii / det. Alicata & Schifani 2018 [Nicolosi (CT) – MSNG]. 1☿, Sicilia / Nicolosi / 24.IV.’912 / leg. A.Fiori // Aphaen. gibbosa fiorii Emery // PARALECTOTYPUS / des. Alicata & Schifani 2018 // Coll.A. Forel // Aphaenogaster fiorii / det. Alicata & Schifani 2018 [Nicolosi (CT) – MHNG].

Additional material examined. MALTESE ISLANDS: M ġ arr, Gozo, 23.iv.1965, leg. C. Baroni Urbani, sub. A. crocea sicula ( BARONI URBANI 1968) (MSNV) ; Mistra, Malta, 22.iv.1965, leg. C. Baroni Urbani, sub. A. crocea sicula ( BARONI URBANI 1968) (MSNM, MSNV) ; Buskett, Malta, 15.iv.1965, leg. C. Baroni Urbani, sub. A. crocea sicula ( BARONI URBANI 1968) (MSNV) ; Tal-Blata (Selmun), Malta, 04.ix.1978, leg. S.P. Schembri, sub A.sicula ( SCHEMBRI & COLLINGWOOD 1981) (SSLM) ; Buskett, Malta, vi.1975, vi.1976, ix.1976, leg. S. P. Schembri, sub A. sicula ( SCHEMBRI & COLLINGWOOD 1981) (SSLM) ; Ghajn Tuffieha, Malta, 27.xii.1975, sub A. sicula ( SCHEMBRI & COLLINGWOOD 1981) , leg. S. P. Schembri ( SSLM); Wied Qannotta, Malta, 25.iii.1978, sub A. sicula ( SCHEMBRI & COLLINGWOOD 1981), leg. S. P. Schembri ( SSLM); Dingli, Buskett, Malta, mixed forest, 29.x.1997, leg. A. Alicata ( AACI); Golden Bay, M ġ arr, Malta, Mediterranean maquis, 31.x.1997, leg. A. Alicata ( AACI); Golden Bay, M ġ arr, Gozo, Malta, meadow, 31.x.1997, leg. A. Alicata ( AACI); San Blas, Gozo, Malta, 36°03 ′ 22.20 ″ N, 14°18 ′ 04.39 ″ E, area populated by marginal synanthropic vegetation near crops, 19.xi.2017, 25 m, leg. R. Viviano ( ESPI); Marfa, Malta, 35°59 ′ 12.78 ″ N 14°19 ′ 51.26 ″ E, 5 m, small area populated by Limonium melitense between a road and a sandy beach in a touristic area, 19.xi.2017, leg. A. Dentici ( ESPI). ITALY: SICILY: Pendici M. Pagano, Caronia (ME), Sicily, Italy, Quercus suber forest, 300 m, 07.xi.1987, pitfall traps, leg. D. Caruso ( AACI); F. S. Paolo, Francavilla (ME), Sicily, Italy, 37°56 ′ 30.27 ″ N, 15°5 ′ 57.81 ″ E, 500 m, deciduous forest of the Quercus pubescens group, 28.vi.1993, leg. A. Alicata ( AACI, MSNM); V.ne Calcinara, Sortino (SR), Sicily, Italy, 37°8 ′ 40.50 ″ N, 14°56 ′ 56.98 ″ E, 565 m, deciduous forest of the Quercus pubescens group, 25.vii.1995, leg.A.Alicata ( AACI); Bosco S. Maria La Stella,Aci S.Antonio (CT), Sicily, Italy, 37°38 ′ 3.62 ″ N, 15°7 ′ 1.04 ″ E, 395 m, deciduous forest of the Quercus pubescens group, 10.iii.1997, leg.A. Alicata ( AACI); Palazzolo Acreide (SR), Sicily, Italy, private garden near the archaeological area, 5.vi.1998, leg.A.Alicata ( AACI); Bosco di Baulì, Noto (SR), Sicily, Italy, 37°01 ′ 53.28 ″ N, 14°56 ′ 21.57 ″ E, 620 m, Quercus ilex forest, 12.vii.1998, leg.A.Alicata ( AACI); Pratofiorito,Adrano (CT), Sicily, Italy, 37°42 ′ 59.90 ″ N, 14°52 ′ 5.17 ″ E, 1,000 m, Quercus ilex forest, 18.v.2002, leg.G.Carcò ( AACI); R.N.O.Grotta Conza (PA), Sicily, Italy, mixed forest, 27.vi.2006, pitfall traps, leg.R.Grasso ( AACI); Buonriposo (EN), Sicily, Italy, 37°36 ′ 20.0 ″ N, 14°14 ′ 41.4 ″ E, 700 m, Quercus pubescens group, pitfall trap, 6.xi.2007, leg. A. Alicata ( AACI).

Worker redescription ( Figs 3, 4, 9 , 12, 13 ). Measurements and indices (42 individuals, 8 localities): HL: 1.14 ± 0.06 (1.05–1.27); HW: 0.97 ± 0.07 (0.82–1.15); CI: 85.28 ± 2.66 (78.57–93.75); FW: 0.85 ± 0.06 (0.75–1.00); SL: 1.23 ± 0.6 (1.12–1.37); SI: 126.48 ± 4.93 (117.77–139.39); MW: 0.61 ± 0.04 (0.52–0.75); ML: 1.53 ± 0.08 (1.37–1.75). Whole body yellow except for first gastral segment which is darker. 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 only slightly marked, the two forming almost continuous dorsal profile in lateral view. In lateral view dorsal profile of metanotum presents slight depression or it is straight. Dorsal profile of propodeum mostly straight, spines variable in size but always well-defined, often oriented upwards. Sculpture relatively weak and shiny 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 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 20, 21, 26 , 29, 30 ). Measurements and indices (3 individuals, 1 locality): HL: 0.68 ± 0.01; HW: 0.72 ± 0.02; CI: 106.12 ± 4.31; FW: 0.46 ± 0.01; SL: 0.20 ± 0.00; SI: 27.60 ± 0.95; MW: 0.82 ± 0.02; ML: 1.67 ± 0.04. Whole body yellowish except for head which is dark brown. All appendages paler than rest of body. Head subtrapezoidal, occipital margin rounded, anterior margin of clypeus convex, 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 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 and suberect to erect setae on gaster. Head finely reticulated, rest of body smooth and shiny.

Queen description ( Figs 35, 36, 41 ). Measurements and indices (4 individuals, 2 localities): HL: 1.48 ± 0.04; HW: 1.46 ± 0.03; CI: 98.75 ± 0.01; FW: 1.25 ± 0.04; SL: 1.42 ± 0.04; SI: 97.42 ± 1.01; MW: 1.35 ± 0.03; ML: 2.53 ± 0.04. Whole body yellowish, with darker areas on gaster. Head subrectangular, lateral surface below eyes slightly 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 relatively long, 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 fiorii stat. nov. was originally described by EMERY (1916) as a subspecies of A. gibbosa (Latreille, 1798) , until SALATA & BOROWIEC (2018a) recombined it as A. subterranea fiorii . They excluded A. fiorii stat. nov. from the gibbosa species group on the basis of its body color, head shape, funicular segments, and length of the scape, claiming that these same characters instead make it part of the A. subterranea species group. Due to the degree of morphological differences from any other congeneric species, relevant in all three castes (see also comparative diagnosis), we consider A. fiorii stat. nov. a bona species.

Comparative diagnosis. Worker. Yellow color of the body and appendages and the darker first gastral tergite allow to distinguish immediately A. fiorii stat. nov. from the vast majority of other sympatric Aphaenogaster species (with the exception of recently emerged workers whose pigmentation is yellowish in many other species). Among the sympatric species, only in A. splendida fully formed workers can appear similarly colored at first sight, but their mesosoma is much more elongated. Lightly colored young workers of other species or specimens with poorly preserved color can all be excluded by examining the mesosoma in lateral view ( Figs 12–19 ): A. fiorii stat. nov. lacks the typical very marked metanotal groove of A. subterranea s. l., the promesonotal suture is significantly less marked than in A. trinacriae sp. nov., and the mesonotum less rounded and convex than in A. sicula or A. trinacriae sp. nov. Among North African species, none shares the unique mesonotal shape or color pattern of A. fiorii . In addition, A. crocea crocea , A. crocea croceoides Forel, 1890 , A crocea splendidoides Forel, 1890 , and A. strioloides Forel, 1890 are considerably more sculptured.

Male. The male of A. fiorii stat. nov. has a yellowish- brown color (except the head) not to be confused with any other sympatric species if color is well preserved. In addition, only some Aphaenogaster males present a mesosoma with an anterior gibbous part and a comparatively flat posterior part like A. fiorii stat. nov. Among the sympatric species that do so, A. splendida can be easily distinguished at the very first sight by different shape of the metathorax, forming a decisively slenderer area before the propodeum in lateral view (see EMERY 1908, 1916). The male of A. sardoa Mayr, 1853 (see SANTSCHI 1911) is larger, darker, with a visibly less gibbous anterior part and much more abundant erect setae on the body. Aphaenogaster trinacriae sp. nov. and A. sicula present the most similar males, but besides being darker, they do not possess the two tubercles on the propodeum as pronounced and with the same shape. In the case of A. sicula the metathorax also forms a slenderer area before the propodeum, and A. 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 A. fiorii stat. nov. from the somewhat similar Maghrebian species: A. crocea (see CAGNIANT 1966), A. faureli Cagniant, 1969 (see CAGNIANT 1969), A. mauritanica Dalla Torre, 1893 (see SANTSCHI 1932, CAGNIANT 1987), A. nadigi Santschi, 1923 (see CAGNIANT 1987), A. strioloides Forel, 1890 (see SANTSCHI 1932), A. theryi Santschi, 1923 (see CAGNIANT 1986, 1996).

Queen. As for the other castes, the color pattern of the yellowish queen of A. fiorii stat. nov. is unique among the other sympatric Aphaenogaster (even A. splendida is more reddish and also bears a well-defined transverse black stripe on the gaster). The mesosoma shape is different from most species, and only shares a significant similarity to A. trinacriae sp. nov., A. sicula and A. subterranea s. l. All of them differ in their color as well as spines shape and length: in A. fiorii stat. nov. the spines are both long and thick. Finally, regarding the Maghrebian Aphaenogaster fauna, the scarcity of information in the literature does not allow a proper comparison with their queens.

Distribution and biogeographical remarks ( Fig. 44 ). Aphaenogaster fiorii stat. nov. is present both in Sicily (from where it was originally described) and the Maltese islands (at least Malta and Gozo). Its presence in the Maltese islands was unknown until now due to misidentification as A. sicula by BARONI URBANI (1968) and SCHEMBRI & COLLINGWOOD (1981). When BARONI URBANI (1968) affirmed that workers of A. crocea sicula from Malta were more monomorphic than the ones of the same species from Sicily, he was comparing misidentified workers of A. fiorii stat. nov. from Malta to misidentified workers of A. subterranea ichnusa Santschi, 1925 from Sicily (material examined by us, published in BARONI URBANI 1964 – the presence of A. subterranea ichnusa in Sicily is illustrated in SCHIFANI & ALICATA 2018). While in Sicily A. fiorii stat. nov. appears to be distinctively rare, in Malta and Gozo it seems much more common (see also under Ecology). This could be partially explained by the reduced competition due to the reduced richness of the local ant fauna in the Maltese islands, including the Aphaenogaster fauna, which is only represented by A. splendida and a few species of the A. testaceopilosa species group there. Conversely, in Sicily A. trinacriae sp. nov., A. sicula , A. subterranea s. l. and perhaps even A. pallida (Nylander, 1849) may represent more pressuring competitors. The SiculoMaltese chorology is known for many other taxa: Sicily and the Maltese islands were connected by a land bridge at least during the last glacial maximum in correspondence with the Hyblaean Plateau in South-Eastern Sicily ( SHACKLETON et al. 1984). To this regard, it is to be noted that A. fiorii stat. nov. is seemingly more common in Eastern Sicily than in Western Sicily. Finally, A. fiorii stat. nov. was once recorded from Sardinia (Iglesias) by GRANDI (1935). Unfortunately, we did not manage to examine any voucher specimen in Grandi’s collection to verify this record. Considering the taxonomic confusion which has affected the identity of this taxon until now, we consider Grandi’s record unlikely to truly refer to A. fiorii stat. nov. and instead possibly related to a misidentification of A. subterranea ichnusa .

Ecology. In Malta the species has been frequently collected in thermophilous oak forest, but it has also been found in open areas such as a meadow on a clay soil (the usual habitat of A. sicula in Sicily), a very small coastal area with Limonium melitense surrounded by a road and a touristic facility, and within an area with synanthropic vegetation near crops. Moreover, it was also collected in a Mediterranean maquis. BARONI URBANI (1968, sub A. crocea sicula ) found it in areas with a relatively large percentage of organic matter, such as anthropogenic areas characterized by trees, shrubs or herbaceous cover. In Sicily, it was found in oak forests and even indoors in a country house, always at higher altitudes than in the Maltese islands. Aphaenogaster fiorii stat. nov. seems to represent the most ecologically varied of the three species here treated in terms of habitat preferences. It is collected between 5 m and 1,000 m.

Conservation. Our data suggest that a large part of the existing global population of this species is concentrated in the relatively small islands of Gozo and Malta, where it is widely distributed. While habitat transformation in these islands probably does not pose a huge risk (see under Ecology), potential future arrivals and outbreaks of dominant invasive ant species may be a serious threat for insular populations, as for example reported in the case of A. hesperia Santschi, 1911 in Tenerife ( BARQUÍN 1981). To this regard, exotic ant species new to the Maltese islands unfortunately continue to be found ( GÓMEZ 2017, SALATA & BOROWIEC 2018b).

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 ( ALICATA 1999). In the wild it can be speculated that nuptial flights may start with the first relevant rains at the end of summer.

Figures

Fig 44. Distribution of Aphaenogaster fiorii Emery, 1915, stat. 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.