Preliminary division of not socially parasitic Greek Temnothorax Mayr, 1861 (Hymenoptera, Formicidae) with a description of three new species

Abstract The division of Greek members of the genus Temnothorax into 17 morphological groups is proposed. Temnothorax aveli species group is reviewed with three species: T. turcicus (Santschi) (North Aegean Islands, Sterea Ellas, Peloponnese and Thessaly), and two species new to science: Temnothorax brackoisp. nov. (Epirus, Ionian Islands, Macedonia, Peloponnese, western Sterea Ellas, Thessaly, and also Dalmatia in Croatia), and T. messiniaensissp. nov. (Ionian Islands and Peloponnese); a new species Temnothorax triangularissp. nov., a member of the Temnothorax nylanderi species group is also described (Sterea Ellas: Euboea Island).


Introduction
The Myrmicinae genus Temnothorax Mayr, 1861 is one of the most speciose in the Mediterranean Region (sensu Vigna Taglianti et al. 1999). Among 279 Palearctic taxa (Bolton 2019), 194 are known from this region (Borowiec 2014, Radchenko et al. 2015, Salata and Borowiec 2015, Csősz et al. 2015, Galkowski and Lebas 2016, Galkowski and Cagniant 2017, Sharaf et al. 2017, Catarineu et al. 2017. Most of the recent research performed on this genus was focused on taxa from European and Anatolian parts of the Mediterranean Region. Those areas are considered as most diverse and species-rich, and each further study confirms this assumption. Greece, located at the joint of European and Anatolian subunits, hosts numerous and various Temnothorax taxa and so it is one of the most challenging fields of research. Study on Greek Temnothorax is additionally impeded by a complicated taxonomical history of several taxa and a lack of new material. Moreover, recent studies published by Csősz et al. (2015Csősz et al. ( , 2018 revealed that species considered as a widespread represent in fact complexes of cryptic taxa. As most of Temnothorax species are morphologically variable, to determine their distribution range and morphological variability, researchers ought to investigate rich material. During several field trips to various places on Greek islands and the mainland, we collected more than 1000 samples of Temnothorax species from 480 localities. The material collected during those expeditions helped us to establish morphological variability within species and divide collected material into several species groups. In most cases, a division into species group is based on species morphology only, and we did not verify if it corresponded with the phylogeny of this genus. This method is a widely accepted tool helping in determining the range of studied material and is commonly practiced (Csősz et al. 2018, Salata and Borowiec 2015, Galkowski and Cagniant 2017, Catarineu et al. 2017). However, we adjusted our species-group definitions to phylogenetical data provided by Prebus (2017) and Csősz et al. (2015). Some Greek Temnothorax have been already included in studies on species groups of T. nylanderi (Csősz et al. 2015), T. interruptus (Csősz et al. 2018), T. recedens (Salata and Borowiec 2015), and T. muellerianus (Salata and Borowiec 2015). Below we present our division of Temnothorax from Greece, which will be used as a base for further studies and we describe three new species: one of them, Temnothorax triangularis, is a member of recently revised T. nylanderi species group (Csősz et al. 2015). Two others are a widespread Greek species, members of the Temnothorax aveli species group. Because Temnothorax taxa known from Crete were revised recently , and the majority of its endemic species creates single-species groups unknown from other Greek regions, they were excluded from this paper. Also, socially parasitic members of Temnothorax, often classified in separate genera Chalepoxenus Menozzi and Myrmoxenus Ruzsky, are not included in this study (see discussion in Seifert et al. 2016 andWard et al. 2016).

Materials and methods
Most of the material was sampled between 2007 and 2019 from sites in different parts of Greece. The main method was direct sampling (hand collecting). Individual specimens and nests were collected on the ground, in leaf litter and rock rubble, under To determine a distribution range and a morphological variability of the new species we compared them with material collected from other Greek regions. Data concerning samples used in the comparison is provided in series of regional checklists (Borowiec and Salata 2012, 2013, 2017a, b, 2018a, b, c, d, e, Bračko et al. 2016) and we see no reason to repeat this information.
Specimens were compared using standard methods of comparative morphology. All measurements were made in μm using a pin-holding stage, permitting rotations around X, Y, and Z axes. A Nikon SMZ18 stereomicroscope was used at a magnification of ×100 for each character. Photographs were taken using a Nikon SMZ 1500 stereomicroscope, Nikon D5200 camera and Helicon Focus software. All given label data of type specimens are in original spelling, presented in square brackets; a vertical bar (|) separates data on different rows and double vertical bars (||) separate labels. Images of type specimens are available online on AntWeb (www.AntWeb.org) and are accessible using the unique CASENT or FOCOL identifying specimen code. If not stated differently material deposited in Museum of Natural History, University of Wrocław (in permanent deposit in the Department of Biodiversity and Evolutionary Taxonomy).

Species groups of Greek Temnothorax
The number of Temnothorax taxa known from Greece is estimated at 59 (including undescribed species) and include recent data published in taxonomic revisions and faunistic papers . Below we present series of morphological characters that were used in species-groups division. Some of the species groups were defined in former publications and we used those descriptions as a base for our research. This applies to the following cases: bulgaricus species group (Radchenko 1995a); affinis species group, tuberum species group, corticalis species group, and clypeatus species group (Radchenko 1995b); nylanderi species group (Radchenko 1995c, Csősz et al. 2015; exilis species group (Cagniant and Espadaler 1997); interruptus species group (Csősz et al. 2018); and recedens species group (Salata and Borowiec 2015). However, in some cases we adapted those definitions to Greek species and thus they differ from the original definitions. We also list members of each species group known from Greece. Taxa known and described from Crete are not included in this division, as they were recently revised in a separate paper , and most of them create separate, single species groups, so far known only from this island. Temnothorax affinis species group: antennae 12-segmented, club not or only slightly darkened, metanotal groove absent, body colouration orange to dark orange with darker head and dark first gastral tergite, propodeal spines very long and thin, straight or only slightly curved, petiole node subangular in profile, head and mesosoma surface moderately sculptured, head completely microsculptured and with more or less developed longitudinal ridges. In Greece only one arboreal species, T. affinis (Mayr).
Temnothorax angustulus species group: antennae 12-segmented, club darkened, metanotal groove feebly marked, body colouration mostly brown to almost black, including head, first gastral tergite mostly brown with yellowish brown basal spot, propodeal spines short to long but thin, straight or slightly curved, petiole node angulate in profile, head and mesosoma surface finely sculptured, head only partly microsculptured, central part more or less shiny, longitudinal ridges diffused visible only in ocular area and sides of head. In Greece only one species known from Mediterranean coniferous forests, T. dessyi (Menozzi).
Temnothorax anodontoides species group: antennae 12-segmented, club darkened, metanotal groove absent, body colouration brown, dark brown to almost black including head, first gastral tergite completely brown to almost black not or only slightly paler at base, propodeal spines very short with broad base, not longer than basal width, petiole node rounded in profile, head and mesosoma surface very strongly sculptured appear partly rugose, head background microsculptured, whole surface with longitudinal ridges or rugosities. In Greece at least three undescribed species known only from high montane localities.
Temnothorax aveli species group: antennae 12-segmented, completely yellow but club sometimes slightly darkened, metanotal groove absent, body colouration mostly yellow including head, sometimes only gena and femora slightly darkened, first gastral tergite with narrow to broad dark posterior band, always with paler spot at base, propodeal spines short to moderately long, with broad base, petiole node rounded in profile, head and mesosoma surface finely sculptured, head almost uniformly, regularly microsculptured, mostly without longitudinal ridges, sometimes only central part of head with narrow area of diffused microreticulation, but head never appears smooth and shiny -in Greece three, revised below, species mostly known from lowland habitats, especially Mediterranean forests and bushes, nestling inside dry stems of trees and twigs of bushes and large herbs-T. brackoi sp. nov., T. messiniaensis sp. nov., T. turcicus (Santschi, 1934), (?)T. tauricus (Ruzsky) (see comments in the redescription of T. turcicus).
Comments: Members of the aveli species group are morphologically similar to those assigned to the tuberum species group. Despite morphological similarities taxa of both groups can be easily distinguished based on nesting and habitat preferences. Species of the aveli species group inhabit lowlands and have nests inside dry stems of trees, bushes and herbs. While Greek species of the tuberum species group occur in the mountain areas and nest in soil, under moss, in rock crevices or debris.
Temnothorax bulgaricus species group: antennae 12-segmented, club usually distinctly darkened, metanotal groove absent, body colouration mostly yellow, sometimes head partly darkened, first gastral tergite with broad dark posterior band, always with yellow spot at base, propodeal spines reduced to triangular tubercle, petiole node rounded in profile, head in central part more or less smooth and shiny, on sides with longitudinal ridges, sometimes almost whole surface of head smooth and shiny or smooth area reduced to a narrow medial stripe, mesosoma laterally with strong sculpture of longitudinal ridges. In Greece two species associated with humid habitats such as stream valleys or bushes inside dark deciduous forests, T. bulgaricus (Forel) and T. nadigi (Kutter).
Temnothorax clypeatus species group: antennae 12-segmented, completely yellow, metanotal groove inconspicuous but well-marked, body colouration ochraceous to reddish brown, first gastral tergite with broad dark posterior band, always with pale spot at base, propodeal spines moderate to long, thorn-shaped, petiole with short peduncle, appears high and bulky in profile, head sculpture from complete, with microreticulate background and more or less developed ridges and costae, to mostly smooth and shiny in central part, only on gena and around eyes with longitudinal ridges, mesosoma laterally with distinct microreticulation and strong reticulate and longitudinal sculpture. In Greece one arboreal species associated with deciduous trees, especially large oaks in sunny habitats, T. clypeatus (Mayr).
Temnothorax corticalis species group: antennae 12-segmented, completely yellow, metanotal groove absent, body colouration ochraceous to light brown, head always more or less darkened, first gastral tergite with broad dark posterior band, always with pale spot at base, propodeal spines from very short, triangular to moderately long needle-shaped, petiole with very short peduncle, appears triangular in profile with more or less angulate node, head sculpture from complete, with more or less reticulate sculpture but shiny background, occasionally in central part of frons reticulation partly diffused, mesosoma dorsally and laterally with distinct microreticulation and often sides of pronotum with longitudinal ridges. In Greece one arboreal species associated with deciduous forests, T. corticalis (Schenck), but occurrence of T. jailensis (Arnoldi) is possible.
Temnothorax exilis species group: antennae 12-segmented, club usually distinctly darkened, metanotal groove absent, body colouration extremely variable, from almost completely yellow to black, often mesosoma paler coloured than head and gaster, first gastral tergite in pale forms with dark posterior band, propodeal spines moderate to long, thin, straight, petiole node angulate in profile, head in central part more or less smooth and shiny, on sides usually with longitudinal ridges, sometimes almost whole surface of head smooth and shiny or smooth area reduced to a narrow medial stripe, mesosoma laterally with strong sculpture of longitudinal ridges. Xerothermophilous species associated with rocky, open and arid habitats; in Greece only T. exilis (Emery) recorded, but based on a high variability of insular populations the real number of species of this group is difficult to estimate and requires further studies.
Temnothorax flavicornis species group: antennae 11-segmented, unicolourous yellow, metanotal groove present, body colouration almost completely yellow to dark yellow, without distinct contrast between colouration of head and mesosoma, first gastral tergite with dark posterior, propodeal spines from long to very long, claw-shaped, from straight to slightly curved, petiole with moderately long peduncle and node angulate, head always with microreticulate background and more or less developed reticulate or costulate sculpture, along middle of head runs stripe with diffused reticulation, more or less smooth and shiny, mesosoma with microreticulate sculpture, often with distinct ridges or costae. One species associated with various arboreal habitats, T. flavicornis (Emery).
Temnothorax graecus species group: antennae 12-segmented, club usually distinctly darkened, metanotal groove absent, body colouration mostly yellow, first gastral tergite with broad dark posterior band, always with yellow spot at base, propodeal spines very short to short, triangular to needle-shaped, petiole node rounded in profile or obtusely angulate, head in central part more or less smooth and shiny, on sides with longitudinal ridges, sometimes almost whole surface of head smooth and shiny or smooth area reduced to a broad medial stripe, mesosoma laterally with moderate sculpture of longitudinal ridges. Associated mostly with moderately humid to arid deciduous forests or mediterranean bushes, collected on rocks and stones; T. aeolius (Forel), T. graecus (Forel), T. smyrnensis (Forel), and at least two undescribed species.
Temnothorax interruptus species group: antennae 12-segmented, club usually distinctly darkened, frontal lobes conspicuously wider than frons, metanotal groove absent or indistinct, body yellow to light brown, gena darker, first gastral tergite with dark posterior band, often interrupted in the middle, propodeal spines very long, thin and curving downwards, petiole node subangulate to obtuse in profile, head with distinct microreticulation and longitudinal ridges, often partly with large reticulate sculp-ture, mesosoma mostly microreticulate, dorsally and laterally more or less rugose or costulate. In Greece two species associated with open habitats such as rocks and stones overgrown by bushes or limestones on mountain pastures, collected also in deciduous or mixed forests, and occasionally in coniferous forests; T. morea Csősz, Salata & Borowiec and T. strymonensis Csősz, Salata & Borowiec. Temnothorax kemali species group: antennae 12-segmented, club usually more or less darkened, occasionally whole antennae yellow, metanotal groove absent, body yellow to orange, gena usually darker, first gastral tergite with dark posterior band, propodeal spines long and thin apically often curving downwards, petiole node subangulate to obtuse in profile, head at least in central part without microreticulation, smooth and shiny, only gena and area around eyes with longitudinal ridges, in some specimens sculpture of sides and central part of head more distinct but area between ridges or costae always smooth and shiny. Species associated with Mediterranean herbs and bushes or dry deciduous and coniferous forests, often nestling inside dry stems of herbs; T. kemali (Santschi) and at least one undescribed species.
Temnothorax luteus species group: antennae 12-segmented, club usually more or less darkened, occasionally whole antennae yellow, metanotal groove absent, body yellow to orange, gena sometimes darker, first gastral tergite with dark posterior band, propodeal spines straight, long and thin, petiole node subangulate in profile, head most often without microreticulation, smooth and shiny, only gena and area around eyes with longitudinal ridges. Xerothermophilous species associated with lowland habitats, Mediterranean herbs and bushes; at least one undescribed species.
Temnothorax nylanderi species group: diverse and speciose group, antennae 12-segmented, unicolourous yellow, metanotal groove usually distinct but in some species inconspicuous, body colouration variable, from almost completely yellow to dark brown but usually without distinct contrast between colouration of head and mesosoma, first gastral tergite usually with dark posterior band (except dark species with unicolourous gaster), propodeal spines from very short, triangular to very long, claw-shaped, from straight to distinctly curved, petiole with moderately long peduncle and node from angulate to obtuse in profile, head always with microreticulate background and more or less developed reticulate or costulate sculpture, sometimes along middle of head runs stripe with diffused reticulation, more or less smooth and shiny, mesosoma with microreticulate sculpture, often with distinct ridges or costae. Species associated with various shadowy habitats, nesting in rock, stones, and dry branches inside forests; T. angulinodis Csősz Prebus (2017) revealed that the nylanderi species group, as defined by Csősz et al. 2015, is paraphyletic and the position of T. flavicornis within it is unlikely. Therefore, we decided to exclude this species from this group and consider it as the single representative of the flavicornis species group.
Temnothorax recedens species group: antennae 12-segmented, unicolourous yellow to brown, metanotal groove very deep, body colouration variable, from almost completely yellow to dark brown, often mesosoma paler coloured than head and gaster, first gastral tergite in pale forms with dark posterior band, propodeal spines from short, triangular to long and thin, the shape of the needle, straight to slightly curved, petiole with long peduncle and node obtuse in profile, head mostly smooth and shiny, pronotum almost completely shiny, mesonotum and propodeum laterally with microreticulate sculpture, without distinct ridges or costae. Species associated with various arboreal habitats, nesting in rock crevices or under moss; T. antigoni (Forel), T. recedens (Nylander), T. rogeri Emery, and T. solerii (Menozzi).
Comment: With great probability this group is more speciose than it is apparent from current data, especially T. recedens shows high regional variability and wide ecological variance, which suggests that this taxon is a group of cryptic species Temnothorax rottenbergi species group: very large species, antennae 12-segmented, club darkened or whole antennae dark, metanotal groove inconspicuous, body completely black or distinctly bicoloured with head and gaster brown to black and mesosoma partly to completely red, propodeal spines very long and strong, apex of spines often curving downwards, petiole with long peduncle and globular node, head with strong reticulate sculpture, mesosoma dorsally and laterally with strong, partly reticulate and partly costate sculpture. Xerothermophilous and alpine species associated with rock and stones on open, sunny habitats such as mountain pastures, grasslands or edges of forests. From Greece T. rottenbergi (Emery) and T. semiruber (André) were recorded but occurrence of first species needs confirmation.
Temnothorax tuberum species group: diverse group, antennae 12-segmented, club darkened, metanotal groove absent or indistinct, mesosoma colouration variable, from almost completely yellow to ochraceous, head always darker coloured than mesosoma, in extreme case almost black, first gastral tergite always with dark posterior band, propodeal spines from short, triangular to moderately long but never needle-shaped, from straight to slightly curved apically, petiole with moderately long peduncle and node subangulate in profile, head always with microreticulate background and more or less developed reticulate or costulate sculpture, without smooth and shiny areas, mesosoma with microreticulate sculpture, often with distinct ridges or costae -species associated with various habitats, from open and sunny to shadowy arboreal, usually nesting in rocks or stones, most species were noted also on rocks on mountain pastures -T. melanocephalus (Emery), T. nigriceps (Mayr), T. tuberum (Fabricius), T. unifasciatus (Latreille), and several undescribed taxa. Comment: Results presented by Prebus (2017) suggest that the tuberum species group (sensu Cagniant and Espadaler 1997) and unifasciatus species group (sensu Bernard 1967) are paraphyletic. In both cases species groups were defined based on West-Mediterranean taxa. Only two Greek members of the tuberum species group were included in analysis presented by Prebus (2017): T. nigriceps and T. unifasciatus and they created a separate cluster. Confirmation, if the tuberum species group as defined by us here is a natural, monophyletic group requires further studies.
A key to Temnothorax species groups known from Greece * Antennal club unicolourous, yellow; metanotal groove usually distinct but in some species inconspicuous; body colouration variable, from almost completely yellow to dark brown but never uniformly coloured (at least legs and antennae brighter); first gastral tergite with dark posterior band or uniformly * Crete, as an island, creates a well-defined unit and studies performed on Temnothorax known from the island were published in a separate paper . The majority of endemic taxa known from the island create a single-species group and the material collected from other Greek islands and regions adjacent to Crete confirms their uniqueness. Therefore, Cretan endemic species of Temnothorax are not included in the key. ** Some specimens of the T. tuberum species group and T. interruptus species group can have very indistinct metanotal grooves. Usually it applies to single specimens within a nest sample. Propodeal spines short to moderately long with broad base; head and mesosoma surface finely sculptured, head almost uniformly, regularly microsculptured, mostly without longitudinal ridges, sometimes only central part of head with narrow area of diffused microreticulation, but head never appears smooth and shiny; petiolar node angulate in profile .. Locus typicus. Peloponnese, Taygetos Mts. Differential diagnosis. Temnothorax brackoi is most similar to T. aveli (Bondroit, 1918), a species widely distributed in the western part of the Mediterranean basin, east to Slovenia. It is similar to T. aveli especially in body shape, petiolar structure and unicolour yellow antennae. Temnothorax aveli differs in microreticulation of head not as regular as in T. brackoi, with slightly shiny surface between sculpture and often with presence of median stripe of diffused microsculpture on frons, while in T. brackoi head sculpture is always homogenous, without areas of diffused microreticulation and dull surface between sculpture. From Greek members of Temnothorax, T. brackoi is most similar to sympatric T. graecus, but differs from it in well-developed sculpture on the whole head surface (in T. graecus central part of frons is more or less shiny, without microreticulation) and larger, distinctly triangular propodeal spines (in T. graecus spines are short, needle-shaped); some specimens of T. brackoi can also be confused with species belonging to the T. tuberum group, but T. brackoi differs from them in low and arched petiolar node and lack of longitudinal striation on frons.
Description. Worker ( Colour. Head, antennae, mesosoma, petiole, postpetiole and legs uniformly yellow to dark yellow, in few specimens, frons and femora partly darkened. Gaster yellow, only the first gaster tergite with wide, dark band on its posterior part (Figs 1, 2). Head. Rectangular, 1.16 times as long as wide, lateral surfaces below and above eyes gently convex, posterior edges convex, occipital margin of head straight or slightly concave (Figs 9, 13). Anterior margin of clypeus slightly convex, medial notch absent. Eyes moderate, oval, 1.4 times as long as wide. Antennal scape short, in lateral view slightly curved, 0.69 times as long as length of the head, in apex gradually widened, its base with small, triangular tooth, funiculus long, club 3-segmented (Fig. 9). Surface of scape with very fine microreticulation, shiny, covered with thin, moderate dense, decumbent to suberect setae. Mandibles rounded with thick sparse, longitudinal striae, shiny. Clypeus shiny with thick, sparse, longitudinal striae, area between striae smooth and shiny. Frontal carinae short, not extending beyond frontal lobes. Antennal fossa deep, with sparse, thin, roundly curved striae and dense reticulation. Frontal lobes narrow, smooth with slight, dense longitudinal striation (Fig. 13). Frons, vertex and temples with dense, thick, reticulation, sometimes central surface of frons with additional a few thin, longitudinal, interrupted wrinkles, surface between striation smooth; malar area with irregular, thick, reticulation, space between reticulation smooth or with very sparse microreticulation, shiny; genae with sparser, thank of frons, and thick reticulation, shiny. Frons and vertex with erect, pale, short and thick setae (Fig. 13). Mesosoma. Elongate, approximately twice as long as wide, slightly arched in profile. Metanotal groove absent. Pronotum convex on sides. Propodeal spines short to moderate, triangular, directed upward, base wide, tips sharp (Fig. 2). Whole surface with dense, reticulation, its dorsal surface and lateral surfaces of pronotum with thick and sparse longitudinal striation or reticulation. Area between thick sculpture shiny, smooth or sometimes with sparse, fait microreticulation. Entire mesosoma bearing erect, pale, short and thick setae (Fig. 2). Petiole. In lateral view, with short peduncle, node low, with anterior face flat, and posterior face convex and dorsum convex. Peduncle and petiolar node shiny, with thick, dense reticulation, area between rugae smooth, dorsum with sparser reticulation. Dorsal surface bearing sparse, short, erect setae (Fig. 2). Postpetiole. In lateral view, regularly convex, apical half with gently convex sides (Figs 1, 2), on the whole surface shiny, with thick, dense reticulation, dorsum with sparser reticulation; area between rugae smooth. Dorsal surface bearing sparse, short, semierect to erect setae (Fig. 2). Gaster. Gaster smooth and shiny, bearing erect, thin, pale setae (Figs 1, 2).
Etymology. Named after Gregor Bračko, a Slovenian myrmecologist, for his significant contributions to the studies on ants of the Balkan Peninsula.
Biology. Specimens of T. brackoi were collected from various localities: sunny and shadowy located on lowlands and highlands (9 -990 m a.s.l). The species was noted in various habitats, most often on shrubs and trees growing along roadsides and olive plantations, maquis, phrygana, often inside forests (mostly deciduous, occasionally coniferous). We noted also its presence on the leaves of climbing plants growing on walls or trees. Nests were not found, probably like other species of this group, are located inside dry stems of herbs.
The Colour. Head, antennae, mesosoma, petiole, postpetiole and legs uniformly yellow to ochre, often posterior part of frons, gena and femora partly darkened, occasionally also antennal club slightly darkened. Gaster yellow, only the first gaster tergite with wide, dark band on its posterior part (Figs 3, 4). Head. Rectangular, but slightly longer than in both Greek congeners, 1.2 times as long as wide, lateral surfaces below and above eyes gently convex, posterior edges convex, occipital margin of head straight or slightly concave (Figs 10, 14). Anterior margin of the clypeus slightly convex, medial notch absent. Eyes moderate, oval, 1.31 times as long as wide. Antennal scape short, in lateral view slightly curved, 0.69 times as long as length of the head, in apex gradually widened, its base with small, triangular tooth, funiculus long, club 3-segmented (Fig. 10). Surface of scape with very fine microreticulation, shiny, covered with thin, moderate dense, decumbent setae. Mandibles rounded with thick sparse, longitudinal striae, shiny. Clypeus shiny with thick, sparse, longitudinal striae, area between striae smooth and shiny. Frontal carinae short, not extending beyond frontal lobes. Antennal fossa deep, with irregular, dense rugosity and sometimes with a few thin, roundly curved striae. Frontal lobes narrow, smooth with slight, dense longitudinal striation (Fig. 14). Frons, vertex and temples with dense, thick, reticulation, central surface of frons with longitudinal reticulation and sometimes with additional thin, longitudinal striation, striae sometimes interrupted, surface between striation smooth; malar area with irregular, thick, reticulation, space between reticulation smooth or with very sparse microreticulation, shiny; genae with sparser, than on frons, and thick reticulation, shiny. Frons and vertex with erect, pale, short and thick setae (Fig. 14). Mesosoma. Elongate, approximately twice as long as wide, slightly arched in profile. Metanotal groove absent or slightly marked as in the species from the Temnothorax angustulus group. Pronotum convex on sides. Propodeal spines long, directed upward, with base slightly to moderate wider than apex, tips sharp (Fig. 4). Whole surface with dense, reticulation, sometimes its dorsal surface and lateral surfaces of pronotum and mesonotum with additional thick, sparse to moderate dense longitudinal striation or longitudinal reticulation. Area between thick sculpture shiny, smooth or sometimes with sparse, fine microreticulation (Fig. 4). Entire mesosoma bearing erect, pale, short and thick setae (Figs 3, 4). Petiole. In lateral view, with short peduncle, node moderate high, with anterior face flat, and posterior face convex and dorsum flat or slightly convex. Peduncle and petiolar node shiny, with thick, dense reticulation and sometimes thick, sparse longitudinal wrinkles, area between rugae smooth, dorsum with sparser reticulation. Dorsal surface bearing sparse, short, erect setae (Fig. 4). Postpetiole. In lateral view, regularly convex, apical half with gently convex sides (Figs 3, 4), on the whole surface shiny, with thick, dense reticulation, dorsum with sparser reticulation; area between rugae smooth. Dorsal surface bearing sparse, short, erect setae (Figs 3, 4). Gaster. Gaster smooth and shiny, bearing erect, thin, pale setae (Figs 3, 4).
Description of gyne (n = 3): Colour. Head in frontal part yellowish brown to brown, gena and temples yellowish, border between dark and pale parts of head dif-fused. Antennae uniformly yellow. Pronotum yellow, scutum yellow laterally and yellowish brown anteriorly, without distinct borders between darker and paler parts. Mesosterna brown, propodeum yellowish dorsally and gradually darker ventrally, petiole and postpetiole brown dorsally and yellow ventrally. Legs mostly yellow, mid-and hind femora largely brown centrally. Gastral tergites mostly brown, first tergite with large yellowish spot basally, all tergites with yellowish to yellowish brown posterior margin (Figs 5, 6). Head. Eyes big, oval [EL / HW: 0.30]. Antennal scape short [SL / HW: 42], not reaching occipital margin of head. Clypeus shiny with distinct, longitudinally carinulae, interstices smooth. Antennal fossa deep, with concentric carinae, interspaces smooth. Frontal lobes moderately wide 0.4 times as wide as head width, microreticulate with thick longitudinal costae. Frons shiny, entire surface longitudinally costate, interstices on sides distinctly microreticulate, in central part microreticulation diffused and surface appears partly smooth and shiny. Area above eyes and sides of head microreticulate and longitudinally costate, interstices appear slightly rugulose. Entire head bearing suberect to erect, pale and thin setae. Mesosoma. Pronotum anteriorly with regular microreticulation and on sides microreticulate with thin longitudinal costae. Scutum with dense, regular, thin longitudinal costae and more or less diffused microreticulation between costae, appears slightly shiny. Scutellum mostly with thin longitudinal costae only marrow median part with diffused sculpture, appears shiny (Fig. 5). Metanotum with slight sculpture, rugulose or punctate. Propodeum with distinct sculpture. Propodeal spines medium length [PSL / HW: 0.33], wide at base, triangular, straight, with acute apex. Area above propodeal spines with transverse, thin costae, dorsal surface of spines with longitudinal costae, sides of propodeum with concentric costae only area close to base of spines distinctly mocroreticulate but without costae, interstices between costae distinctly microreticulate, shiny. Area between propodeal spines on sides with longitudinal costae, centrally with distinct microreticulation, area below spines with transverse costae. Anepisternum and katepisternum with longitudinal costae and microreticulated interspaces, only anterior and posterior corners of anepisternum with small smooth and shiny areas, and katepisternum close to ventral margin with diffused costae. Metaepisternum and metakatepisternum, with dense, longitudinal costae and microreticulate interspaces only metakatepisternum close to ventral margin with diffused microreticulation and partly shiny. Dorsal surface of mesosoma with sparse, erect, long, thick and pale setae (Figs 5,6). Petiole and postpetiole. Shiny anteriorly, dorsal and lateral surface microreticulate with sparse longitudinally costae. Gaster. Smooth and shiny, first tergite on whole surface and rest of tergites posteriorly bearing moderately dense, long, erect setae and sparse, short adhering setae (Figs 5, 6).
Etymology. Named after the historical Greek land of Messinia (Μεσσηνία), Peloponnese, where specimens from the type series were collected.
General distribution. Greece 1000 m, 37.19874N/2257603E, 1000, 2016-06-18, leg 855 m, 2017-05-09, leg. L. Borowiec. Terra typica. Greece, Thessaly, Mt. Ossa. Differential diagnosis. Differentiation from T. kemali, T. brackoi and T. messiniaensis -see differential diagnosis in T. messiniaensis. Temnothorax turcicus differs from specimens of T. aveli with long propodeal spines in thin dark band on first gastral tergite, head not darker from mesosoma, mesosoma less convex in profile and propodeal spines directed slightly more upwards; from T. lagrecai (Baroni Urbani, 1964) Colour. Whole body uniformly yellow to dark yellow, sometimes club in darker yellow colouration. Gaster yellow, only the first gaster tergite with very thin, dark band on its posterior part (Figs 7, 8). Head. Oval, 1.16 times as long as wide, lateral surfaces below and above eyes gently convex, posterior edges convex, occipital margin of head straight or slightly convex (Fig. 15). Anterior margin of clypeus slightly convex, medial notch absent. Eyes moderate, oval, 1.34 times as long as wide. Antennal scape short, in lateral view slightly curved, 0.69 times as long as length of the head, in apex gradually widened, its base with small, triangular tooth, funiculus long, club 3 segmented (Figs 12, 15). Surface of scape with very fine microreticulation, shiny, covered with thin, moderate dense, decumbent setae. Mandibles rounded with thick sparse, longitudinal striae, shiny. Clypeus shiny with thick, sparse, longitudinal striae, area between striae smooth and shiny. Frontal carinae short, not extending beyond frontal lobes. Antennal fossa deep, with irregular, dense to sparse, thick rugosity and sometimes with a few thin, roundly curved striae, surface between thick sculpture smooth or with sparse microreticulation. Frontal lobes narrow, smooth with slight, dense longitudinal striation (Fig. 15). Frons, vertex and temples with dense, thick, longitudinal reticulation, central surface of frons and vertex with longitudinal reticulation sparser or reduced, with additional thin, longitudinal striation, striae sometimes interrupted, surface between striation smooth and shiny; malar area with irregular, thick, reticulation, space between reticulation smooth or with very sparse microreticulation, shiny; genae with sparser, than on frons, and thick reticulation, shiny (Fig. 15). Frons and vertex with erect, pale, short and thick setae. Mesosoma. Elongate, 1.98 times as long as wide, slightly arched in profile. Metanotal groove absent. Pronotum convex on sides. Propodeal spines long, directed upward, with base slightly to moderate wider than apex, tips sharp (Fig. 8). Whole surface with dense, reticulation, sometimes its dorsal surface and lateral surfaces of pronotum and mesonotum with additional thick, sparse longitudinal wrinkles. Area between thick sculpture shiny, smooth or sometimes with sparse, fine microreticulation (Fig. 8). Entire mesosoma bearing erect, pale, short and thick setae (Fig. 8). Petiole. In lateral view, with short peduncle, node moderate high, with anterior face straight, and posterior face convex and dorsum flat or slightly convex. Peduncle and petiolar node shiny, with thick, dense reticulation, area between rugae smooth, dorsum with sparser reticulation. Dorsal surface bearing sparse, short, erect setae (Fig. 8). Postpetiole. In lateral view, regularly convex, apical half with gently convex sides (Fig. 8), on the whole surface shiny, with thick, dense reticulation, dorsum with sparser reticulation; area be- tween rugae smooth. Dorsal surface bearing sparse, short, erect setae. Gaster. Gaster smooth and shiny, bearing erect, thin, pale setae (Figs 7, 8).
Comment. We examined a syntype of Temnothorax tauricus (Ruzsky, 1902) preserved in Forel's collection (MHNG) and it appears to be very similar to specimens of T. turcicus collected in Greece. The only difference is a slightly darkened antennal club in the syntype specimen of T. tauricus (all studied specimens of T. turcicus have antennae uniformly yellow). We discussed this issue with Alex Radchenko (Kiev, Ukraine) who confirmed that all 17 syntypes of T. tauricus preserved in Karavaiev's collection (Kiev, Ukraine) also have slightly darkened antennal club. In our opinion this difference could be an infraspecific variation. Within nest samples of Temnothorax messiniaensis, a member of the aveli species group, we observed single specimens with more or less darkened antennal club. Temnothorax tauricus was recorded from Caucasus and southern Ukraine but is sympatric with T. turcicus in Bulgaria and Greece. Temnothorax tauricus have nests in dry stems of herbs, grasses or rarely in soil under stones (Radchenko 2016) and by those preferences reminds species of the T. aveli species group. Clarification of taxonomic relation between those two taxa requires further study based on material collected from the whole distribution range of both species. If our supposition on the conspecifity of both taxa is confirmed, then the name T. tauricus will have priority over the name T. turcicus.
Biology. Specimens collected on shadow localities, from seacoast to 1000 m a.s.l. Foraging workers were observed on herbs in stream valley of tourist resort, valleys with Platanus trees, mountain coniferous forest and mountain pastures close to border of coniferous forest. Nests were not found, probably like other species of this group, are located inside dry stems of herbs.
The following ant species were recorded in the same areas as Propodeal spines short to moderate (PSI<155), triangular, with wide base (Fig. 2); head on whole frontal surface with regular reticulation, without longitudinal striation, with dull background (Fig. 13) Differential diagnosis. Temnothorax triangularis belongs to the T. nylanderi species group. It differs from most of members of this group in uniformly brown body with darker frons and posterior band of first gastral tergite, and absent or very shallow, inconspicuous metanotal groove. There are four other known species with dark body colouration: T. laconicus, T. artvinensis, T. sordidulus, and T. tergestinus. Temnothorax triangularis differs from all of them in extremely shallow metanotal groove and frons lacking reticulation and covered with dense, thick, longitudinal striations, additionally frons centre has sculpture weaker or reduced, it differs also from T. laconicus and T. artvinensis in shorter, triangular propodeal spines. dense, thick, longitudinal striation, sparser or reduced in the central part, striae sometimes interrupted, surface between striae smooth and shiny; space between frontal carinae ad eyes, temples and malar area with longitudinal, thick reticulation, space between reticulation smooth or with very sparse microreticulation, shiny; genae with very sparse thick reticulation, partly smooth, always shiny. Frons and vertex with erect, pale, short and thick setae. Mesosoma. Elongate, 1.9 times as long as wide, slightly arched in profile. Metanotal groove absent or very shallow, inconspicuous. Pronotum convex on sides. Propodeal spines short, triangular, with wide base, directed upward, with angulate tips (Fig. 21), only in fewer than 20% of specimens are propodeal spines moderately long, with wide bases and sharp tips (Fig. 22). Lateral surfaces of pronotum with thick and sparse longitudinal striation or reticulation, its dorsal surface with thick, sparse, irregular reticulation; mesonotum and propodeum on the whole surface with thick, denser than on pronotum, irregular reticulation. Area between thick sculpture shiny, smooth or sometimes with sparse, fine microreticulation (Fig. 17). Entire mesosoma bearing erect, pale, short and thick setae (Fig. 17). Petiole. In lateral view, with short peduncle, node high, with anterior face flat to slightly convex, and posterior face and dorsum convex. Peduncle and petiolar node shiny, with thick, dense reticulation, area between rugae smooth, dorsum with sparser reticulation. Dorsal surface bearing sparse, short, erect setae (Figs 21, 22). Postpetiole. In lateral view, regularly convex, apical half with gently convex sides (Figs 21, 22), on the whole surface shiny, with thick, dense reticulation, dorsum with sparser reticulation; area between rugae smooth. Dorsal surface bearing sparse, short, semierect to erect setae. Gaster. Smooth and shiny, bearing erect, thin, pale setae (Figs 16, 17). Description of gyne (n = 2). Colour. Head brown, temples slightly brighter coloured than frontal parts. Antennae uniformly yellow. Mesosoma, petiole and postpetiole bright brown, legs yellow. First gastral tergite mostly dark brown with yellowish brown spot basally, remaining tergites brown with dark brown posterior margins (Figs 23,24). Head. Eyes big, almost round [EL / HW: 0.26]. Antennal scape short [SL / HW: 0.76], not reaching occipital margin of head. Clypeus smooth and shiny laterally with diffused, longitudinal carinulae. Antennal fossa deep, rugulose with concentric carinae. Frontal lobes wide 0.43 times as wide as head width, rugulose with thick longitudinal costae, interstices microreticulate (Fig. 20). Frons shiny, entire surface longitudinally costate and rugose, interstices distinctly microreticulate. Area above eyes and sides of head rugulose and partly longitudinally costate, only small area behind eyes smooth and shiny. Entire head bearing erect, pale and thin setae. Mesosoma. Pronotum with thick rugosities in anterior part, sides with thick rugosity and dense longitudinal costae. Surface between rugosities microreticulate. Scutum with dense, thick longitudinal costae and microreticulation between costae but appears shiny. Scutellum laterally with thick longitudinal costae, to the centre costae partly diffused, along middle smooth and shiny area (Figs 23, 24). Metanotum with fine longitudinal costae and microreticulated background. Propodeum with area above propodeal spines with transverse and on sides with longitudinal costae and microreticulated background. Propodeal spines short [PSL / HW: 0.28], triangular, with wide base, straight and angulate apex. Area between and below propodeal spines with distinct microreticulation tends to form transverse ridges. Anepisternum and katepisternum with gentle, dense longitudinal costae. Metaepisternum and metakatepisternum, with dense, longitudinal costae and shiny area close to ventral margin. Surface between costae microreticulate. Dorsal surface of mesosoma with sparse, erect, long, thick and pale setae (Figs 23, 24). Petiole and postpetiole. Microreticulate, the entire surface punctate to rugulose, dorsal surface longitudinally costulate. Gaster. Smooth and shiny, bearing sparse, long, erect setae (Figs 23, 24). General distribution. Greece, Sterea Ellas, Euboea. Biology. Alpine species. Ants were observed on stones, dry branches, and herbs in coniferous forest, or coniferous forest with an admixture of chestnut. Nests were found in the dry branches of conifers lying on the ground.
The following ant species were recorded in the same areas as T. triangularis: helenae Csősz et al., T. unifasciatus  Note. Although this species has inconspicuous metanotal groove, which tends to disappear in some specimens, we decided to place it in the Temnothorax nylanderi group. General body shape, structure of petiole, unicolourous antennae, head and mesosoma sculpture presented by T. triangularis are very similar to those observed in large species of the group i.e. T. nylanderi (Förster), T. crassispinus (Karavaiev) or T. crasecundus Seifert & Csősz. Moreover, an inconspicuous metanotal groove was observed also in some samples of small species of the nylanderi group, such as T. helenae Csősz, Heinze & Mikó. Usually the depth of metanotal groove is more or less constant within nest samples.