Temnothorax algiricus ( Forel, 1894 )

Temnothorax algiricus ( Forel, 1894) View in CoL

Figure 5 View FIGURE 5

= Leptothorax angustulus var. brunea Santschi, 1918 View in CoL syn. n.

= Leptothorax gazella Santschi, 1932 View in CoL

= Leptothorax gazella var. monticola Santschi, 1932

= Temnothorax mediterraneus Ward, Brady, Fisher, & Schultz, 2014 syn. n.

= Temnothorax atlantis veneris Galkowski & Cagniant, 2017 syn. n.

Investigated type material: 2 syntype workers of algiricus ( Msila Forest, Oran, Algeria) from the MHNG ( Geneva, Switzerland), being the mid and bottom specimens of a pin in which the top worker had its head missing with the labels “TYPUS // L. angustulus / Nyl / / [worker symbol] / v. algiricus Forel / Foret de Msila / ( Algerie) // Coll. A. Forel // algiricus Forel ”. 1 syntype worker of T. algiricus investigated through AntWeb (CASENT0909011—MHNG, Geneva, Switzerland). 1 syntype worker of brunea investigated through AntWeb (CASENT0912895—NHMB, Basel, Switzerland). 1 syntype worker of gazella investigated through AntWeb (CASENT0912940—NHMB, Basel, Switzerland). 1 syntype worker of monticola investigated through AntWeb (CASENT0912941—NHMB, Basel, Switzerland). 1 syntype worker of veneris investigated through AntWeb (CASENT0917823—SIZK, Kiev, Ukraine). 1 syntype worker of mediterraneus (= Leptothorax angustulus kraussei Emery, 1916 ) (Cagliari, Sardinia, Italy) investigated through AntWeb (CASENT0904755—MSNG, Genoa, Italy).

Investigated non-type material: 79 workers from 39 colonies from Algeria, Italy, Croatia, France , and Spain.

Worker redescription. Body either concolor dark brown to blackish, or bicolored, with parts or the entirety of the mesosoma and nodes being reddish or ferruginous and contrasting with the head and gaster. Antennae, legs, and mandibles often lighter than the body.

Head subrectangular with rounded margin, clypeus and mandibles rounded. Antennae of 12 segments, antennal clubs of 3 segments. Compound eyes are ovoidal. The mesosoma may or not present a slight metanotal impression visible in lateral view on the dorsal profile. Propodeal spines relatively long and erect, sometimes arched in dorsal view, and slightly curved in lateral view. The petiole has a triangular shape, with a small tooth-like subpetiolar process. The postpetiole has an ordinary ovoidal lateral profile and may appear subhexagonal in dorsal view.

Surface sculpture is generally fine, with larger parts of the head becoming dull in smaller specimens; a fine irregular sculpture in the rest of the body, with some striae on the dorsum of the mesosoma, often on the head, and always a central carina in the clypeus.

Very sparse, usually erect setae all over the body; dense, fine, and mostly adpressed pilosity on the antennae.

Diagnosis. Compared to T. trabutii , the propodeal dorsum has a gentler transition with the rest of the mesosoma and is less steep [PropH2/PropH1: 0.897 ( 0.732, 1.069)]. Several morphometric characters have an intermediate position between T. atlantis and T. trabutii . Spines form a narrower angle with the mesosoma than in T. atlantis but not as much as in T. trabutii [no range overlaps in SpANG: 130 (119, 139)]. On average, the propodeal spines are shorter than in T. trabutii but longer than in T. atlantis [SPST/CS: 0.329 (261, 409)]. In dorsal view these are divergent at first but may curve inwards in their distal part, the ratio between their maximum width and the width between their tips being averagely larger than in T. atlantis but smaller than in T. trabutii [SPWI/SPBA: 1.382 ( 1.108, 1.750)]. The ratio between the spines divergence and their length is also intermediate [SPWI/SPST: 0.829 ( 0.628, 1.222)]. Pigmentation can be concolor dark, or bicolored with dark head and gaster contrasting with the reddish mesosoma and nodes (as in the types of mediterraneus and veneris).

Distribution. Southern Spain, Balearic Islands, Morocco, Algeria, Tunisia, Sicily (including circum-Sicilian islands), Sardinia, Corsica, Italian peninsula (including the Tuscan archipelago), and Croatia. Records from the Maltese Islands should be attributed to this species.

Taxonomic history. Temnothorax algiricus was described by Forel (1894) from Algeria ( Oran province) as a North African variety of the European T. angustulus with a different color. Some following authors kept considering it a variety of angustulus ( Santschi 1911; 1918; Emery 1924; Bolton 1995). However, it was mostly treated as a species since Cagniant (1968) elevated it to species rank, although he did not provide a justification for his decision (e.g., Cagniant & Espadaler 1997; Bračko 2006; Cagniant 2006; Guillem 2009; Borowiec 2014; Galkowski & Lebas 2016; Lebas et al. 2016; Galkowski & Cagniant 2017). Later, Cagniant & Espadaler (1997) synonymized under T. algiricus four other taxa. Nonetheless, Galkowski & Cagniant (2017) could not provide a morphological distinction from T. mediterraneus Ward et al., 2014 . The name T. algiricus was almost exclusively used in North Africa, with two exceptions: Bračko (2006) listed it among the species of Croatia, and Guillem (2009) recorded it in the Balearic Islands.

Leptothorax angustulus algiricus View in CoL bruneus Santschi, 1911 is an unavailable infrasubspecific name ( Santschi 1911), while Santschi (1918) made the first available use of the name as Leptothorax angustulus var. brunea Santschi, 1911 View in CoL . It was described from Algeria (Yakouren) and defined as more strongly sculptured than T. algiricus View in CoL , darker than T. trabutii View in CoL , and “transitional” to silvanus ( Forel, 1907) . Cagniant & Espadaler (1997) synonymized this taxon under T. atlantis View in CoL , considering it a dark-colored variety and speculating that the darker pigmentation could be caused by an association with more humid environments. Galkowski & Cagniant (2017) raised it to the subspecies level as T. atlantis brunea , again suggesting the same mechanism behind the dark pigmentation and stronger sculpture. In general, selective pressure for darker pigmentation in ants has been demonstrated to be associated with either high UV exposure on one hand or low temperatures on the other (Law et al. 2019; Bishop et al. 2021).

Leptothorax gazella Santschi, 1932 View in CoL was described from Tunisia ( Sousse, see Santschi 1932) and said to be similar to “ L. angulatus View in CoL ” (almost certainly a mistype of T. angustulus View in CoL , as no “ L. angulatus View in CoL ” has ever been described). Santschi (1932) differentiated L. gazella View in CoL from “ L. angulatus View in CoL ” due to the first having a less pronounced metanotal impression. In the same paper, Santschi (1932) described L. gazella var. monticola View in CoL , also from Tunisia (Aïn Draham), based on a darker gaster and minor sculpture differences from L. gazella View in CoL s. str. Both taxa were considered synonyms of T. algiricus View in CoL by Cagniant & Espadaler (1997) without providing an explanation.

Temnothorax mediterraneus Ward, Brady, Fisher, & Schultz, 2014 View in CoL is a replacement name for Temnothorax kraussei Emery, 1916 View in CoL (= Leptothorax angustulus kraussei Emery, 1916 View in CoL ), a junior secondary homonym of Temnothorax kraussei Emery, 1915 View in CoL . The latter is a socially parasitic species originally described as Epymyrma kraussei , but the genus Epymyrma was found to be a synonym of Temnothorax View in CoL by Ward et al. (2014). Under either of the two different names, this species has long been considered part of the faunas of Italy ( Baroni Urbani 1971; Schifani 2022), France ( Casevitz-Weulersse & Galkowski 2009), Malta ( Schembri & Collingwood 1995), and Spain ( Arcos & Garcia 2023). The original description by Emery (1916) as a variety of T. angustulus View in CoL ( Leptothorax angustulus var. kraussei View in CoL ) considered it to occur in Corsica, Sardinia, and Sicily, and the type is from Sardinia. Emery (1916) distinguished the var. kraussei View in CoL by having a stronger head sculpture and sometimes a ferruginous mesosoma (in other specimens very dark). While Baroni Urbani (1971) treats T. mediterraneus View in CoL as a distinct species based on its sympatry with T. angustulus View in CoL in Sicily, Rigato & Toni (2011), in a faunistic paper on Sardinian ants, suggested potential synonymy between T. mediterraneus View in CoL and T. angustulus View in CoL . Eventually, Espadaler & Collingwood (1989), working on Iberian ants, defined the presence of a middle clypeal carina and the reddish mesosoma as distinctive features separating T. mediterraneus View in CoL from T. angustulus View in CoL . Ultimately, the taxon was redescribed by Galkowski & Cagniant (2017), who further demonstrated its distinctiveness from T. angustulus View in CoL . In addition, they separated the populations of mainland Iberia and mainland France that were until that point considered to belong to T. mediterraneus View in CoL by describing them as T. continentalis View in CoL , while considering T. mediterraneus View in CoL a valid species exclusive to Corsica, Sardinia, and Sicily. Coherently with the original description, T. mediterraneus View in CoL was defined as a taxon of variable pigmentation (with a reddish to dark mesosoma), different from T. continentalis View in CoL because of the longer and differently shaped spines, and together with T. continentalis View in CoL separate from T. angustulus View in CoL by the middle clypeal carina ( Galkowski & Cagniant 2017). However, Galkowski & Cagniant (2017) could not identify any character separating T. mediterraneus View in CoL from T. algiricus View in CoL .

Leptothorax angustulus trabutii View in CoL veneris Santschi, 1918 is an unavailable (infrasubspecific) name ( Bolton 1995). Santschi (1918) described it from Tunisia ( Le Kef) as similar in color to T. trabutii View in CoL but characterized by a stronger sculpture and different spines. Galkowski & Cagniant (2017) described the subspecies T. atlantis veneris based on one of the syntypes of the taxon described by Santschi, providing a valid name for it. However, they could not find characters to separate the subspecies veneris from the nominal subspecies of T. atlantis ( Galkowski & Cagniant 2017) View in CoL . At the same time, Galkowski & Cagniant (2017) also considered other syntypes (all from the same locality), including “CASENT0912897”, as “typical T. mediterraneus View in CoL ” and one as T. santschii (Forel, 1905) View in CoL due to its longer spines [ T. santschii View in CoL is a species with a long petiolar peduncle considered close to T. flavispinus (André, 1883) View in CoL ]. Furthermore, they stated that they had never found T. mediterraneus View in CoL but only T. algiricus View in CoL in Tunisia and kept considering T. mediterraneus View in CoL a European taxon. There is no “CASENT0912897” on AntWeb, and we have no data of T. atlantis View in CoL east of central Algeria; while we have not examined the same specimens that Galkowski & Cagniant (2017) used to make their assessments, we based our evaluation on the only specimen present on AntWeb (CASENT0917823), which due to its availability we suggest to consider the lectotype of the taxon in future revisions.

Leptothorax convexus var. timida Santschi, 1912 , described from Morocco (Cap Spartel, near Tangier, see Santschi 1912) was considered a junior synonym of T. algiricus View in CoL by Cagniant & Espadaler (1997), who did not provide any argument for this decision as for the other synonymizations of taxa under T. algiricus View in CoL . It is notable that, in the same paper, Cagniant & Espadaler (1997) also treated T. convexus ( Forel, 1894) View in CoL as a separate taxon but member of the same angustulus View in CoL group. Pictures of the type of L. convexus var. timida are available on AntWeb (CASENT0912920) and clearly show that it does not belong to the T. algiricus View in CoL complex but instead bears all the typical features of T. convexus View in CoL including the shape of the mesosoma, propodeal spines, nodes, and the surface sculpturing (also see Arcos et al. 2022). Therefore, we remove L. convexus var. timida from synonymy with T. algiricus View in CoL and consider it as a junior synonym of T. convexus View in CoL .

Comments. The works of Espadaler & Collingwood (1989) and, more importantly, Galkowski & Cagniant (2017) were fundamental contributions for the understanding of this species in Europe (under T. mediterraneus ), by separating it first from T. angustulus , and then from T. atlantis (under T. continentalis ). However, the relationship between the populations in South Europe (under kraussei Emery, 1916 and then T. mediterraneus ) and those in North Africa (under T. algiricus ) remained unresolved, with no character found to tell them apart for more than a century, during which a parallel taxonomy existed. Furthermore, we found significant oversplitting in North Africa, where brunea, gazella , monticola, and veneris were all found to be indistinguishable from, and thus synonymized to, T. algiricus . Biogeographically, the distribution of T. algiricus mirrors the distribution of many North African ant species that also occur in southern Europe: in Italy (Schifani et al. 2022; Schifani & Alicata 2023), with some species extending to Croatia at their easternmost limit ( Baroni Urbani 1971) and in the very south of Iberia and the Balearic Islands ( Arcos & Alarcón 2024). Worth noting, a worker from Italy (Taormina, Sicily; CASENT0906170) currently listed as T. angustulus on AntWeb belongs to T. algiricus based on our morphological analysis.