Temnothorax triangularis, Salata, Sebastian & Borowiec, Lech, 2019

Salata, Sebastian & Borowiec, Lech, 2019, Preliminary division of not socially parasitic Greek Temnothorax Mayr, 1861 (Hymenoptera, Formicidae) with a description of three new species, ZooKeys 877, pp. 81-131 : 81

Temnothorax triangularis sp. nov. Figs 16-17 , 18-20 , 21, 22 , 23-24

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.

Etymology.

Named after short, triangular propodeal spines.

Type material.

Holotype, worker (pin) (CASENT0846901): GREECE, Sterea Ellas, Eubea | 2.4 km SW of Stropones | 38,60327N / 23,87E, 1025 m |10 VI 2018, L. Borowiec || Collection L. Borowiec | Formicidae | LBC-GR02682 (MNHW).

Paratypes, 25w., 1Q.(pin) (CASENT0846661-CASENT0846691): the same nest sample as holotype (DBET, BMNH, CASC, MHNG); 5w. (EtOH): the same locality as holotype, collected in litter (DBET); 11w, 1Q (pin) (CASENT0846692-CASENT0846704): GREECE, Sterea Ellas | Eubea |3.7 km SW of Metochi, 830 m | 38.60402N / 23.91683E, | 13 VI 2018, L. Borowiec (DBET).

Terra typica.

Euboea, Greece.

Other material.

GREECE, Sterea Ellas, Euboea: 2w. (EtOH): 1.5 km SW of Koutourla, 38.62838N / 23.92772E, 695 m, 2018-06-13, leg. L. Borowiec; 1w.(pin) (CASENT0846902), 2w. (EtOH): 2.3 km S of Stropones, 38.9933N / 23.87807E, 860 m, 2018-06-10, leg. L. Borowiec; 2w. (EtOH): 2.7 km SE of Stropones, 38.59851N / 23.9085E, 855 m, 2018-06-13, leg. L. Borowiec; 3w. (EtOH): 2.9 km S of Stropones, 38.59133N / 23.88562E, 880 m, 2018-06-13, leg. L. Borowiec; 43w. (EtOH): 3.7 km SW of Metochi, 38.60402N / 23.91683E, 830 m, 2018-06-13, leg. L. Borowiec.

Description of worker (n = 10): HL: 0.684 ± 0.01 (0.671-0.708); HW: 0.603 ± 0.02 (0.578-0.650); SL: 0.504 ± 0.02 (0.484-0.534); EL: 0.140 ± 0.01 (0.124-0.149); EW: 0.105 ± 0.006 (0.093-0.112); WL: 0.769 ± 0.02 (0.742-0.820); PSL: 0.161 ± 0.02 (0.143-0.183); SDL: 0.119 ± 0.006 (0.112-0.130); PEL: 0.294 ± 0.02 (0.273-0.323); PPL: 0.182 ± 0.008 (0.174-0.199); PEH: 0.245 ± 0.01 (0.236-0.270); PPH: 0.231 ± 0.01 (0.217-0.248); PNW: 0.403 ± 0.01 (0.388-0.435); PLW: 0.177 ± 0.009 (0.168-0.199); PPW: 0.241 ± 0.01 (0.230-0.267); CI: 88.2 ± 2.2 (85.3-92.7); SI1: 73.7 ± 1.5 (71.2-76.4); SI2: 83.6 ± 2.4 (78.9-87.5); MI: 52.4 ± 1.2 (50.8-54.7); EI1: 75.0 ± 4.2 (68.8-85.0); EI2: 15.3 ± 1.0 (13.6-16.7); PI: 120.1 ± 5.4 (108.0-128.8); PPI: 79.0 ± 2.8 (75.0-85.7); PSI: 135.8 ± 12.4 (120.0-155.6).

Colour.

Whole body uniformly brown to bright brown, sometimes mesosoma and genae brighter. Legs and antennae bright brown to dark yellow, femora in central part darkened ( Figs 16 , 17 ). Head. Oval, 1.14 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 18 , 19 ). Anterior margin of the clypeus slightly convex, medial notch absent. Eyes small, oval, 1.33 times as long as wide. Antennal scape short, in lateral view slightly curved, 0.73 times as long as length of the head, in apex gradually widened, its base with small, triangular tooth, funiculus long, club 3-segmented ( Fig. 18 ). 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, longitudinal striae, area between striae shiny with few longitudinal wrinkles. Frontal carinae short, not extending beyond frontal lobes. Antennal fossa deep, with sparse, thin roundly curved striae, area between striae with sparse and fine reticulation, shiny. Frontal lobes narrow, smooth with slight, dense longitudinal striation ( Figs 18 , 19 ). Space between frontal carinae and vertex with 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 :

Sterea Ellas, Euboea, 1.5 km SW of Koutourla: Aphaenogaster subterranea (Latreille), Formica fusca Linnaeus, Lasius alienus Förster, L. brunneus (Latreille), L. illyricus Zimmermann, Pheidole pallidula (Nylander), Plagiolepis pygmaea (Latreille), P. pallescens Forel, Temnothorax helenae Csősz et al., T. lichtensteini (Bondroit), T. unifasciatus (Latreille); 2.3 km S of Stropones: see Temnothorax brackoi ; 2.4 km SW of Stropones: Camponotus aethiops (Latreille), Formica fusca Linnaeus, F. sanguinea Latreille, Lasius alienus Förster, L. illyricus Zimmermann, Messor structor (Latreille), Temnothorax crasecundus Seifert & Csősz, T. unifasciatus (Latreille), Tetramorium impurum ( Förster); 2.7 km SE of Stropones: Aphaenogaster subterranea (Latreille), A. cf. subterranea , Camponotus aethiops (Latreille), C. oertzeni Forel, Formica fusca Linnaeus, Lasius alienus Förster, L. distinguendus (Emery), Tapinoma erraticum (Latreille), Temnothorax helenae Csősz et al., T. unifasciatus (Latreille);

2.9 km S of Stropones: Camponotus piceus (Leach), C. vagus (Scopoli), Lasius brunneus (Latreille), L. flavus (Fabricius), Myrmica scabrinodis Nylander, Temnothorax helenae Csősz et al., T. unifasciatus (Latreille); 3.7 km SW of Metochi: Aphaenogaster subterranea (Latreille), A. cf. subterranea , Camponotus fallax (Nylander), C. vagus (Scopoli), Lasius illyricus Zimmermann, Temnothorax crasecundus Seifert & Csősz, T. helenae Csősz et al., T. unifasciatus (Latreille).

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.

Figures

Figures 16, 17. Worker of Temnothorax triangularis sp. nov. 16 Dorsal 17 Lateral.

Figures 18 - 20. Temnothorax triangularis sp. nov. 18 Worker head and antennae 19 Worker head sculpture 20 Gyne head and antennae.

Figures 21, 22. Variation of propodeal spines of Temnothorax triangularis sp. nov.

Figures 23, 24. Gyne of Temnothorax triangularis sp. nov. 23 Dorsal 24 Lateral.