Redescription of Temnothorax antigoni (Forel, 1911) and description of its new social parasite Temnothorax curtisetosus sp. n. from Turkey (Hymenoptera, Formicidae)

Abstract Temnothorax antigoni (Forel, 1911) is redescribed basing on a new material from southwestern Turkey (Antalya province), Lesbos and Rhodes (Greece, Aegean and Dodecanese islands). The gyne of this species is described for the first time. Temnothorax curtisetosus, a new species of social parasite collected in a nest of Temnothorax antigoni, is described. Colour photos of both taxa are given. A key to the worker caste of the eastern Mediterranean species belonging to both Temnothorax recedens and Temnothorax muellerianus groups are provided.


Introduction
The genus Temnothorax Mayr, 1861 is one of the most speciose in the Myrmicinae subfamily. The most recent catalogue lists 380 valid species and 47 valid subspecies (Bolton 2015). Most species are distributed in northern hemisphere, mostly in temperate and warm temperate habitats, including taxa occurring in mountain habitats. More than a half of the described taxa are known from Europe and the Mediterranean basin (Borowiec 2014). HW head width; measured above the eyes in full-face view; MH mesosoma height; measured from the upper edge of mesonotum to the lowest point of the mesopleural margin, in lateral view; ML mesosoma length; measured as diagonal length from the anterior end of the neck shield to the posterior margin of the propodeal lobe; PH petiole height; maximum height of petiole in lateral view; PL petiole length; maximum length of petiole in lateral view; PPH postpetiole height; maximum height of postpetiole in lateral view; PPL postpetiole length; maximum length of postpetiole in lateral view; PPW postpetiole width; maximum width of postpetiole in dorsal view; PW petiole width; maximum width of petiole in dorsal view; SDL spiracle to declivity length; minimum distance from the center of the propodeal spiracle to the propodeal declivity; SL maximum straight-line length of the scape; SPBA maximum distance between outer margins of spines measured at the base; SPT maximum distance between outer margins of spines measured at the top; PSL propodeal spine length; measured from the center of the propodeal spiracle to the top of the propodeal spine.
All lengths are in millimeters.
Redescription. Worker (n=20). Measurements and indices: HL: 0.659 ± 0.04 (0.581-0.721); HW: 0.521 ± 0.032 (0.458-0.581); EL: 0.125 ± 0.09 (0.112-0.142); EW: 0.094 ± 0.005 (0.089-0.106); SL: 0.641 ± 0.039 ( Whole body pale yellow, including antennae and legs, only first gastral tergite with pale, brown, regular transverse band apically (Figs 1, 2). Head 1.2-1.3 times as long as wide, posterior margin of the head straight and laterally rounded in full-face view, gena almost parallel-sided (Fig. 7). Eyes small, 1.3 times as long as wide, gena 1.5 times as long as eye length, distance between line connecting hind margins of eyes to posterior margin of head 1.8 times as long as eye length. Anterior margin of clypeus regularly rounded, clypeal lines distinct, slightly divergent, reaching to line connecting anterior margin of eyes. Almost entire surface of head smooth and shiny, only gena with indistinct microreticulation. Clypeus, frons and top of head with numerous, long, erect hairs, the longest hair to 1.2 times longer than eye width, ventral surface of head with numerous long hairs, on the top of head hairs only slightly shorter. Antennal scape approximately as long as head, thin, in widest part only 1.8 times as wide as antennal base. Surface of scape smooth and shiny, covered with long, moderately dense, erect hairs. Funiculus 1.2 times as long as scape with three-segmented thin club, first segment twice longer than wide, second segment 1.3 times as long as wide, segments 3-5 approximately as long as wide, club very long, 0.75 times as long as segments 1-9 combined. Mesosoma elongate, 2.8 times as long as wide, with deep metanotal groove. Pronotum rounded on sides, regularly convex in profile, smooth and shiny, with 8-20 long, erect hairs. Promesonotal suture very fine but visible, mesonotum forms with pronotum regular arch, surface smooth and shiny with 4-8 long hairs. Mesopleura with regular granulate sculpture, metapleural suture distinct. Propodeum slightly convex in profile, surface with granulate sculpture but shiny, propodeal spines very short, triangular (Fig. 2), metapleura with granulate sculpture. Petiole elongate, 1.6 times as long as high, dorsal surface shallowly concave, petiolar lobe regularly rounded, ventral margin of petiole straight, carinate, with small, sharp denticle at the base. Petiolar lobe almost parallel-sided in dorsal view, then slightly converging to base. Petiolar lobe smooth and shiny with 4 long erect hairs, sides of petiole with granulate sculpture. Postpetiole globular in profile, from dorsal view slightly transverse with subangulate sides (Fig. 1), top of postpetiole smooth and shiny with 4-6 long, erect hair, sides with granulate sculpture. Gaster as long as meso- soma, surface smooth and shiny covered with numerous long, erect hairs (Fig. 2). Legs elongate, smooth and shiny, with sparse, semierect hairs, femora along underside with row of 3-4 long erect hairs. Hind tarsus 1.6 times as long as hind tibia.
Description Whole body pale yellow, including antennae and legs, only first gastral tergite with pale brown, regular transverse band apically and subsequent tergites with brownish posterior margin (Figs 3, 4).
Head 1.1 times as long as wide, posterior margin of head rounded in full-face view, gena almost parallel-sided (Fig. 8). Eyes large, 1.4 times as long as wide, gena 0.7 times as long as eye length, distance between line connecting hind margins of eyes to posterior margin of head 1.3 times as long as eye length. Anterior margin of clypeus regularly rounded, clypeal lines distinct, slightly divergent, reaching slightly behind line connecting anterior margin of eyes. Upper half of head smooth and shiny, frons on sides microreticulate but shiny, gena with rugose sculpture and along inner margin of eye run 2-3 thin carinae. Clypeus, frons and top of head with numerous, moderately long, erect hairs, the longest hairs slightly shorter than eye width, ventral surface of head with numerous moderately long hairs. Antennal scape 1.1 times as long as head, thin, in widest part only 1.6 times as wide as antennal base. Surface of scape smooth and shiny, covered with moderately long, moderately dense, more or less erect hairs. Funiculus 1.2 times as long as scape with three-segmented thin club, first segment twice as long as wide, second segment as long as wide, segments 3-5 elongate 1.3-1.4 times as long as wide, club long, approximately as long as segments 1-9 combined. Mesosoma 1.8 times as long as wide. Pronotum narrow, not visible from above, smooth and shiny. Scutum of mesonotum convex, smooth and shiny, covered with numerous moderately long, erect setae. Scutellum convex, smooth and shiny with view erect setae. Anepisternite with indistinct microreticularion, shiny, mesopleuron smooth and shiny. Propodeum short, surface with few transverse carinae, propodeal spines short, 1.1 times as long, acute, near apex with one long seta ( Fig. 4), metapleura with distinct carinae. Petiole elongate, 1.5 times as long as high, dorsal side almost flat, petiolar lobe subangulate in profile, with short carina on sides, distinctly microreticulate, ventral margin of petiole straight, carinate, with small, sharp denticle at base. Petiolar lobe feebly rounded on sides in dorsal view, then distinctly converging to base. Petiolar lobe behind top microreticulate with two long setae. Postpetiole globular in profile, from dorsal view distinctly transverse, 1.3 times as wide as long, with carinate sides (Fig. 3), top of postpetiole microreticulate with several thin, longitudinal carinae and 7-9 long, erect setae, sides microreticulate with few short carinae. Gastral tergites smooth and shiny covered with numerous long, erect hairs (Fig. 4). Legs elongate, smooth and shiny, with moderately dense, semierect to erect hairs, femora along underside with row of 4-5 long erect hairs. Hind tarsus 1.7 times as long as hind tibia.
Differential diagnosis. Temnothorax antigoni is a species belonging to the former subgenus Temnothorax sensu stricto. The following related species occur in the eastern  Workers of Temnothorax finzii distinctly differ by a very large eyes (EI > 24.8 in T. finzii vs EI < 20.3 in T. antigoni) and a longitudinal striation with rugosity covering entire lateral surface of the head while the head in T. antigoni is smooth and shiny. Another four species are very similar: T. rogeri differs in very long propodeal spine, at least twice as long as its width at base (in T. antigoni the spine is short, forms a denticle, not or only slightly longer than its width at base), T. solerii differs in entire body uniformly yellowish-brown to brown (in T. antigoni the body is uniformly pale yellow with darker transverse apical band on the first gastral tergite). At the first glance T. antigoni can be mistakenly determined as a pale variation of T. recedens. Workers of T. recedens are always bicoloured with head and gaster mostly dark and mesosoma usually with a darker spots on meso-and metapleura. Even pale workers of this species have always head and gaster gently darker than mesosoma with a pale basal spot on the first gastral tergite. In our collection we possess 17 gynes and 262 workers from 67 localities in Spain, Italy, Greece and Cyprus (see Suppl. material 1) and we have never found a specimens with colouration typical for T. antigoni (more than 230 examined specimens). In T. antigoni head and mesosoma are uniformly yellow, devoid of any darker discolourations and the gaster is mostly yellow with a darker transverse apical band on the first gastral tergite. This colouration is constant in all examined samples. The only observed variability was a degree of saturation of dark apical band on the first gastral tergite. Moreover, T. antigoni has average smaller eyes than T. recedens (EI: 18.8 ± 0.8 in T. antigoni vs 22.0 ± 1.6 in T. recedens).
Gynes are known only for Temnothorax recedens and T. rogeri. The gyne of T. rogeri distinctly differs in long propodeal spine, distinctly longer than width at base, head partly infuscate and gaster mostly brown with yellow spot at base of first tergite (in T. antigoni propodeal spine is triangular, as long as wide, body mostly uniformly yellow with darker transverse apical band on first gastral tergite and narrowly infuscate apical margin of subsequent tergites). The gyne of T. recedens differs in head and mesosoma usually bicoloured, with at least infuscate spot on meso-and metapleura, and mostly dark gaster (in T. antigoni the body is mostly uniformly yellow with darker transverse apical band on the first gastral tergite and narrowly infuscate apical margin of subsequent tergites).
Biological data. In Turkey a nest of Temnothorax antigoni was found under a stone on a rocky side of a sandy path which runs through a pine forest. The locality is placed inside archeological site of the ancient Greek city Phaselis, close to the sea, only 6 m a.s.l. In the three Rhodes localities nests were found in rocks in mountain pine forest habitats at altitudes 522-598 m. Nests were located between schists of the volcanic rocks placed in the shade. In the five Lesbos localities nests were found in pine forest, oak forest and river valleys with platanus trees at altitudes 74-485 m. Nests were located under a moss overgrowing a large stones and between a schists of the volcanic rocks placed in the shade. A single workers were collected also on the surface of large stones or rocks. The following ant species were recorded in the same areas as T. antigoni: Distribution. Described from Turkey: "Coccarinali près Smyrne" [now Izmir, Izmir province]. New locality in Turkey (ancient Phaselis) is placed in Antalya province approximately 370 km southeast from the type locality, three localities on Rhodes (Greece, Dodecanese) are placed 231-139 km southwest from the second locality in Turkey, and localities on Lesbos are placed 100-120 km northwest from the type locality (Fig. 16). Species new to Greek fauna.
A key to the worker caste of the East Mediterranean species belonging to the T. recedens group.  Head yellowish, in dorsal half slightly darker than in frontal parts and below eyes. Mesosoma, petiole, postpetiole, antennae and legs uniformly yellowish, first gastral tergite yellowish-brown with paler large patch at base, subsequent tergites yellowishbrown, sternites yellow (Figs 9, 10).
Head 1.4 times as long as wide, posterior margin of head straight and laterally rounded in full-face view, gena almost parallel-sided (Fig. 11). Eyes moderately large, 1.2 times as long as wide, gena 1.2 times as long as eye length, distance between line connecting hind margins of eyes to posterior margin of head 1.3 times as long as eye length. Anterior margin of clypeus regularly rounded, clypeal lines distinct, slightly divergent, reaching to the line connecting posterior margin of eyes. Almost whole surface of head smooth and shiny, only gena with rugose sculpture and along inner and outer margin of eye run 2-3 thin carinae. Clypeus, frons and top of the head with numerous, moderately long, erect hair, the longest hairs slightly shorter than eye width, ventral surface of head with numerous moderately long hairs. Antennal scape 0.8 times as long as head, thin, in widest part only 1.5 times as wide as antennal base. Surface of scape smooth and shiny, covered with moderately long, moderately dense, more or less erect hairs. Funiculus 1.3 times as long as scape with threesegmented thin club, first segment 1.8 times as long as wide, second segment as long as wide, segments 3-5 slightly transverse, club very long, only slightly shorter than segments 1-9 combined. Mesosoma elongate, 2.5 times as long as wide, with deep metanotal groove. Pronotum rounded on sides, regularly convex in profile, smooth and shiny, with 5-6 moderately long and few short, erect hairs. Promesonotal suture very fine but visible, mesonotum forms with pronotum regular arch, dorsal surface smooth and shiny with 4-8 moderately long hairs, sides with few longitudinal carinae. Mesopleura with indistinct microreticularion and few carinae. Propodeum distinctly convex in profile, surface with indistinct microreticulation but shiny, with 5-6 moderately long erect setae, propodeal spines short, 1.1 times as long as width at base, acute, near apex with one long seta (Fig. 10), metapleura with indistinct microreticularion and few carinae. Petiole short, 1.1 times as long as high, dorsal surface shallowly concave, petiolar lobe rounded, on sides with short carina, ventral margin of petiole straight, carinate, at base with moderately large, sharp denticle. In dorsal view petiolar lobe almost round, then distinctly converging to base. Petiolar lobe smooth and shiny with 4 long and two short erect hairs, sides of petiole microreticulate but shiny. Postpetiole globular in profile, from dorsal view distinctly transverse, 1.4 times as wide as long, with regularly rounded sides ( Fig. 9), top of postpetiole smooth and shiny with 8-10 moderately long, erect hair, sides microreticulate with few short carinae. Gaster slightly shorter than mesosoma, surface smooth and shiny covered with numerous moderately long, erect hairs (Fig. 10). Legs elongate, smooth and shiny, with sparse, semierect to erect hairs, femora along underside with row of 3-4 long erect hairs. Hind tarsus 1.4 times as long as hind tibia. Differential diagnosis. Temnothorax curtisetosus sp. n. belongs to a monophyletic group of social parasites formerly classified as a separate genus Chalepoxenus Menozzi and recently synonymized with Temnothorax Mayr (Ward et al. 2015  Temnothorax curtisetosus and T. muellerianus (Finzi) differ significantly from other members of this group in having tibiae covered with long, erect setae. Temnothorax muellerianus is the most widely distributed and the most variable species of this group (Buschinger et al. 1988). Temnothorax curtisetosus distinctly differs from T. muellerianus in very short setae on the mesosoma, petiole and postpetiole (Fig. 12 versus Fig.  13), and especially on gastral tergites (the total length of 10 setae combined on the first tergite is 741 µm in T. curtisetosus vs. 1111-1325 µm in T. muellerianus Figs 14-15). Temnothorax curtisetosus is smaller than most specimens of T. muellerianus and has shorter antennal scapes and higher SI index. At the first glance T. curtisetosus reminds a workers of T. finzii. Besides a clear differences in the biology of these species, T. finzii is a non-parasitic species inhabiting dry open habitats and nesting deep in the soil, usually under stone (Bračko et al. 2014), these species can be distinguished also in morphological features. T. curtisetosus differs from T. finzii by a weaker longitudinal striation covering only sides of the frons and its head is devoid of rugosity (in T. finzii whole head is covered by longitudinal striation with rugosity between it) and in presence of a dentiform plate on the ventral margin of the petiole, a character associated  with a Chalepoxenus line. Moreover T. curtisetosus has also smaller propodeal spines (SPI < 31.7 vs SPI>40.8 in T. finzii).
Distribution. SW Turkey, Antalya Province. Comments. We found only two workers of Temnothorax curtisetosus in a nest of Temnothorax antigoni. The large number of gynes in relation to number of workers of the host species (5 gynes/6 workers) suggests that the nest was in the initial stage. Both specimens of the parasite have constant characters, especially very short dorsal setae. Very small specimens of T. muellerianus have dorsal setae proportionally 1.5 times longer than both specimens of T. curtisetosus. Kutter (1973) and Buschinger et al. (1988), basing on a large material from the entire Mediterranean basin, discussed variability and status of several taxa closely related to T. muellerianus but none of the samples studied by them were characterized by short dorsal setae. Although we have only two specimens of T. curtisetosus, the clear gap in the length of dorsal setae between these specimens and all examined samples of T. muellerianus (37 workers from 12 localities of 4 countries, see Suppl. material 1), a shorter propodeal spines and the analysis of variability within various populations of T. muellerianus discussed by Buschinger et al. (1988) convinced us to describe these two specimens as a species new for science.
A key to a worker caste of east Mediterranean species belonging to the T. muellerianus group is provided below.  Figure 16. Distribution of Temnothorax antigoni (Forel), blue circle -locus typicus, red circle -new locality in Turkey (also locus typicus for Temnothorax curtisetosus sp. n.), yellow circles -new localities in Rhodes, black circle -new localities in Lesbos.