Temnothorax crassispinus

Temnothorax crassispinus is a forest species which typically lives in cavities in fallen twigs and acorns; colonies usually number from a few dozen to about 200 workers (Mitrus, 2019). Zryanin & Zryanina (2007) found it nesting in wood fragments within deciduous and pine forests. Apparently some nests were mixed with Temnothorax nylanderi although specific details of their relation is unknown.

Identification
Csösz et al. (2015) - A member of the nylanderi species-complex. Temnothorax crassispinus may be confused with other long-spined species treated in this revision: Temnothorax angulinodis, Temnothorax laconicus, Temnothorax lichtensteini and Temnothorax parvulus. Temnothorax angulinodis clearly differs from T. crassispinus by its sharply angulate petiolar node in lateral view (72–82°). In T. crassispinus, the frontal profile and the truncate dorsum of the petiole meet in an obtuse angle (100–115°). The deviation of the propodeal spines from longitudinal mesosomal axis (in lateral view) helps to separate T. crassispinus (32–42°) from T. laconicus and T. lichtensteini (20–25°). Temnothorax parvulus differs from T. crassispinus in the surface sculpturing on the head dorsum. If the samples are dust-covered, other measures can also help: T. crassispinus is considerably larger (CS), has a higher petiolar node (SPST/CS), and a wider head (CL/CWb) than T. parvulus.

Temnothorax crassispinus shares most of its main characteristics, shape and surface sculpturing, with its siblings, Temnothorax crasecundus and Temnothorax nylanderi. The simple propodeal spine length ratio (SPST/CS) helps to separate nest samples of T. crassispinus from those of T. nylanderi without error, but the same character overlaps between nest sample means of T. crassispinus and Temnothorax crasecundus. The shortest discriminant formula (D4) that separates T. crassispinus from T. crasecundus with a classification success rate 95% in single individuals and 97% in nest sample means is D4 = +0.0392*SL -0.0746*SPST +0.0933*SPL -0.0295*SPWI -7.2179.

Distribution
This species is distributed from the Balkans to Central Europe. The distributional area of Temnothorax crassispinus lies between the ranges of its two parapatric relatives, Temnothorax nylanderi in the West and Temnothorax crasecundus in the East.

Distribution based on Regional Taxon Lists
Palaearctic Region: Albania, Austria, Belarus, Bosnia and Herzegovina, Bulgaria, Croatia, Czech Republic, Estonia, Germany, Greece, Hungary, Italy, Latvia, Lithuania, Montenegro, Poland, Republic of Macedonia, Republic of Moldova, Romania, Russian Federation, Serbia, Slovakia, Slovenia, Ukraine.

Biology
Mitrus et al. (2017) - common and widely distributed in Central and Eastern Europe (Czechowski, 2012). This ant species lives in light coniferous and mixed forests (Seifert, 2007; Czechowski et al., 2012). Colonies of the ant are small, typically ranging from a few dozen to several hundreds of workers (Seifert, 2007; Czechowski et al., 2012). However, the density of colonies locally can be high, and the average number of inhabited nest sites could be higher than 2 nests m−2 (Strätz & Heinze, 2004; Białas et al., 2011), and the ant plays a considerable role in seed dispersal (Fokuhl et al., 2012).

Temnothorax crassispinus colonies form nests in cavities in logs plus in acorns and small sticks situated in the litter layer (Seifert, 2007; Czechowski et al., 2012). They can use more than a single nest site in the summer, i.e., exhibit seasonal polydomy. If potentially good nest sites are covered by leaves or overgrown by herbaceous plants or bushes, they are rarely used by ants (S. Mitrus, pers. obs.). Such overshadowing could affect, e.g. temperature and moisture (Ruckli et al., 2013). In forests, where the ant typically lives, different herb species could form dense stands and significantly change environmental conditions at a local scale. In southern Poland, balsams (Impatiens spp.) are a plant species that typically form such stands, and they could overshadow potentially good nest sites for the ant.

The maximum observed foraging distance of workers of T. crassispinus was 162 cm, with an average of 52 cm (Fokuhl et al., 2012).

A field experiment examined nest use in artificial nests placed in and out of areas with native Impatiens noli-tangere and the naturalized introduced species I. parviflora, both forest flowing balsam species. The ant was found to be more frequent in places without balsam cover. Nests within balsam areas were smaller and were more frequently found without queens.

Nomenclature

 *  crassispinus. Leptothorax (Leptothorax) nylanderi var. crassispina Karavaiev, 1926f: 69 (w.q.) UKRAINE.
 * Combination in Temnothorax: Bolton, 2003: 271.
 * Subspecies of nylanderi: Karavaiev, 1927c: 266 (in key).
 * Junior synonym of nylanderi: Karavaiev, 1934: 137; Bolton, 1995b: 237; Radchenko, 1995d: 3.
 * Status as species: Radchenko, 2000: 44; Czechowski, et al. 2002: 50; Seifert, 2007: 239; Czechowski, et al. 2012: 148; Seifert & Csösz, 2015: 40; Csösz, Heinze & Mikó, 2015: 38 (redescription).
 * Senior synonym of slavonicus: Radchenko, 2000: 44; Csösz, Heinze & Mikó, 2015: 38.
 * slavonicus. Leptothorax nylanderi subsp. slavonicus Seifert, 1995: 4, figs. 5, 6, 10, 15, 17, 20 (w.q.) GERMANY.
 * Status as species: Seifert, 1996b: 127, 229.
 * Junior synonym of crassispinus: Radchenko, 2000: 44; Csösz, Heinze & Mikó, 2015: 38.

Worker
Csösz et al. (2015) - Body color: brown; yellow. Body color pattern: mesosoma, antenna and legs, waist and anterior region of 1st gastral tergite lighter than head and posterior region of gaster. Antenna color pattern: clava concolorous funicle. Absolute cephalic size: 544–688 μm (mean = 623, n = 42). Cephalic length vs. Maximum width of head capsule (CL/CWb): 1.100–1.180 (mean = 1.140). Postocular distance vs. cephalic length (PoOc/CL): 0.379–0.403 (mean = 0.390). Postocular sides of cranium contour frontal view orientation: converging posteriorly. Postocular sides of cranium contour frontal view shape: strongly convex. Vertex contour line in frontal view shape: straight. Vertex sculpture: main sculpture parallel costate, ground sculpture areolate. Genae contour from anterior view orientation: converging. Gena contour line in frontal view shape: convex. Gena sculpture: rugoso-reticulate with areolate ground sculpture. Median region of antennal rim vs. frontal carina in frontal view structure: not fully overlapped by frontal carina. Concentric carinae laterally surrounding antennal foramen count: present. Eye length vs. absolute cephalic size (EL/CS): 0.247–0.268 (mean = 0.256). Frontal carina distance vs. absolute cephalic size (FRS/CS): 0.362–0.399 (mean = 0.377). Longitudinal carinae on median region of frons count: present. Longitudinal carinae on medial region of frons shape: not forked. Smooth median region on frons count: absent. Antennomere count: 12. Scape length vs. absolute cephalic size (SL/CS): 0.756–0.811 (mean = 0.784). Facial area of the scape absolute setal angle: 0–15°. External area of the scape absolute setal angle: 30°. Ground sculpture of submedian area of clypeus: smooth. Median carina of clypeus count: present. Lateral carinae of clypeus count: present. Median anatomical line of propodeal spine angle value to Weber length in lateral view: 32–42°. Spine length vs. absolute cephalic size (SPST/CS): 0.288–0.356 (mean = 0.329). Minimum spine distance vs. absolute cephalic size (SPBA/CS): 0.282–0.339 (mean = 0.312). Maximum spine distance vs. absolute cephalic size (SPWI/CS): 0.362–0.421 (mean = 0.389). Apical spine distance vs. absolute cephalic size (SPTI/CS): 0.342–0.397 (mean = 0.366). Maximum mesosoma width vs. absolute cephalic size (MW/CS): 0.509–0.662 (mean = 0.626). Metanotal depression count: present. Metanotal depression shape: shallow. Dorsal region of mesosoma sculpture: rugulose with areolate ground sculpture. Lateral region of pronotum sculpture: areolate ground sculpture, main sculpture forked costate. Mesopleuron sculpture: areolate ground sculpture superimposed by dispersed rugulae. Metapleuron sculpture: areolate ground sculpture superimposed by dispersed rugulae. Frontal profile of petiolar node contour line in lateral view shape: concave. Dorsal profile of petiolar node contour line angle value to frontal profile of petiole contour line in lateral view: 100–115°. Anterodorsal rim of petiole count: absent medially. Dorsal profile of petiolar node contour line in lateral view shape: slightly convex. Dorsal region of petiole sculpture: ground sculpture areolate, main sculpture dispersed rugose; ground sculpture areolate, main sculpture absent. Dorso-caudal petiolar profile contour line in lateral view shape: straight; concave. Dorsal region of postpetiole sculpture: ground sculpture areolate, main sculpture dispersed rugose; ground sculpture areolate, main sculpture absent.

Type Material
Csösz et al. (2015) - Syntype workers of Leptothorax nylanderi var. crassispina Karavajev, 1926: Golossev near Kiev, Leg. Karawajew, “No. 3057 Col. Karawajew” (7##, CASENT0914703) [UKR:Golossev-crassispinus-TYPE].

Paratype workers of Leptothorax nylanderi slavonicus Seifert, 1995: Germany, Kr. Görlitz, Hutberg Schönau-Berzdorf, 19.03.1993. Seifert (4## ) [GER:Hutberg-slavonicus-TYPE].