Temnothorax estel, González, 2021

González, Javier Arcos, 2021, Description of Temnothorax estel sp. nov. (Hymenoptera: Formicidae), with a review of the Iberian species of the sordidulus species-complex, Zootaxa 5005 (2), pp. 145-160 : 150-154

Temnothorax estel sp. nov.

( Fig. 2B and 6B , worker; Fig. 3 , queen)

Type material. Holotype worker: Spain, Serra d’Aitana (Alacant), 20.VI.2020, 38°39’05.6”N 0°14’13.7”W, 1282 m (MCNB code MZB 2021-0727) . Paratypes: 4 workers, same nest and date as holotype (MCNB codes MZB 2021- 0728, MZB 2021-0729, MZB 2021-0730 and MZB 2021-0731); 5 workers, same nest and date as holotype (will be deposited in MNHN); 5 workers, same nest and date as holotype (will be deposited in CASC).

Additional studied material. 2 workers, Serra d’Aitana (Alacant), 09.IV.2012, 38°39’00.4”N 0°13’28.7”W, 1247 m ; 14 workers, 1 queen, 13 males, Siles , Sierra de Cazorla (Jaén), 30.VI.2016, 38°22’38.7”N 2°31’03.7”W, 1425 m ; 10 workers, 10 males, Serra d’Aitana (Alacant), 20.VI.2020, 38°39’05.6”N 0°14’13.7”W, 1282 m ; 20 workers from 2 nests, Sierra de Cazorla (Jaén), 26.IX.2020, 37°48’48.1”N 2°57’36.6”W, 1796 m ; 30 workers from 2 nests, Sierra de Cazorla (Jaén), 26.IX.2020, 37°48’10.4”N 2°58’14.4”W, 1649 m .

Diagnosis. Characterized within the Iberian sordidulus species-complex by being bicolored, with yellowish mesosoma and darker head dorsum; sculpture of frons entirely reticulated; head elongate (mean HL/HWb 1.275); metanotal groove inconspicuous to very shallow; and with the longest propodeal spines of the complex (mean SPST/CS 0.313).

Description of worker (n=50). HL: 0.635 ± 0.031 (0.570 –0.693) mm; HWb: 0.499 ± 0.032 (0.453 –0.564) mm; PoOC: 0.246 ± 0.015 (0.222 –0.268) mm; EL: 0.126 ± 0.007 (0.111 –0.139) mm; FRS: 0.192 ± 0.013 (0.176 –0.213) mm; SL: 0.472 ± 0.029 (0.425 –0.527) mm; LDFS: 0.222 ± 0.008 (0.208 –0.236) mm; LMH: 0.062 ± 0.009 (0.048 – 0.083) mm; ML: 0.714 ± 0.039 (0.656 –0.786) mm; MH: 0.292 ± 0.024 (0.254 –0.333) mm; MGr: 0.001 ± 0.002 (0–0.007) mm; SPST: 0.174 ± 0.014 (0.157 –0.194) mm; SPL: 0.112 ± 0.015 (0.083 –0.139) mm; PEL: 0.236 ± 0.025 (0.208 –0.287) mm; PEH: 0.204 ± 0.015 (0.179 –0.231) mm; NOL: 0.161 ± 0.014 (0.139 –0.185) mm; SPEPH: 0.038 ± 0.006 (0.028 –0.046) mm; PECW: 0.130 ± 0.008 (0.120 –0.139) mm; PPL: 0.141 ± 0.010 (0.129 –0.157) mm; PPH: 0.168 ± 0.012 (0.152 –0.194) mm; USH: 9.385 ± 1.293 (6–10.5) mm; SPTI: 0.180 ± 0.019 (0.153 –0.213) mm; SPWI: 0.191 ± 0.018 (0.159 –0.224) mm; SPBA: 0.132 ± 0.019 (0.110 –0.166) mm; PW: 0.341 ± 0.022 (0.313 –0.383) mm; PEW: 0.139 ± 0.013 (0.116 –0.166) mm; PPW: 0.188 ± 0.014 (0.162 –0.213) mm. See Table 2 for the indexes.

Size. Small species in the sordidulus species-complex (mean CS 0.567 mm).

Coloration pattern. Bicolored species. Dorsum of head dark brown, contrasting with yellowish mesosoma. Antennal club not darkened. Ventral side of head, mandibles, antennae and legs yellowish. Femora occasionally darkened. Tergites of gaster with a dark and diffuse band on their distal third; rest of gaster yellow.

Head. Antenna of 12 segments. Head strongly elongated (mean HL/HWb 1.275). In frontal view, sides of head parallel, converging posteriorly. Posterior margin of head straight. Anterior margin of clypeus rounded. Eyes small (mean EL/CS 0.223 mm). Postocular distance similar to the rest of species (PoOC/HL 0.387). Frontal carinae very narrow (mean FRS/CS 0.339). Scape long, but not reaching the posterior margin of head (mean SL/CS 0.831). Mandible of five teeth. Frons with reticulated ground sculpture and distinct but not strong superimposed longitudinal striae, with very narrow and smoother median region. Clypeus surface smooth and shiny, with 9–11 longitudinal carinae; a median and two paramedian carinae are often more pronounced. Concentric rugae visible on genae.

Mesosoma. Indistinct to shallowly impressed metanotal groove (mean MGr/CS 0.220%). Pronotum narrow (mean PW/CS 0.601 mm). Propodeal spines longer than any other species in the complex (mean SPST/CS 0.308 mm), curved and deviating from longitudinal axis of mesosoma by 45°; in smaller individuals, spines may be much thinner and longer. Declivity before propodeal spines usually present in lateral view. Whole surface of mesosoma with reticulated ground sculpture and superimposed longitudinal striae, which are more developed on lateral margins of pronotum. Setae on mesosoma short (mean LMH/CS 0.110).

Petiole and postpetiole. Petiole high, with concave anterior face and truncated apex. Usually, a transverse and pronounced carina crosses the petiole in lateral view. Petiolar cylinder narrow than any other species in the complex (mean PECW/PEH 0.229). Subpetiolar process well developed (mean SPEPH/CS 0.067), with rounded apex and occasional concave anterior face. Postpetiole subquadrate in dorsal view, getting narrower towards the base. Petiole and postpetiole narrow in dorsal view (mean PEW/CS 0.245; mean PPW/CS 0.332).

Description of queen (n=1). HL: 0.730 mm; HWb: 0.675 mm; PoOC: 0.290 mm; EL: 0.185 mm; FRS: 0.268 mm; SL: 0.536 mm; LDFS: 0.231 mm; LMH: 0,066 mm; ML: 1.282 mm; MH: 0.656 mm; SPST: 0.259 mm; SPL: 0.139 mm; PEL: 0.324 mm; PEH: 0.287 mm; NOL: 0.213 mm; SPEPH: 0.046 mm; PECW: 0.194 mm; PPL: 0.194 mm; PPH: 0.250 mm; SPTI: 0.287 mm; SPWI: 0.305 mm; SPBA: 0.277 mm; PW: 0.804 mm; PEW: 0.203 mm; PPW: 0.277 mm. Indexes: CS: 0.703; HL/HWb: 1.080; PoOC/HL: 0.397; FRS/CS: 0.382; SL/CS: 0.763; EL/CS: 0.263; LDFS/CS: 0.329; LMH/CS: 0.092; ML/CS: 1.825; MH/CS: 0.934; SPST/CS: 0.368; SPL/CS: 0.197; PEL/ CS: 0.461; NOL/CS: 0.303; PEH/CS: 0.408; PPL/CS: 0.276; PPH/CS: 0.355; SPEPH/CS: 0.066; PECW/CS: 0.276; PEW/CS: 0.289; PPW/CS: 0.395; SPWI/CS: 0.434; SPTI/CS: 0.408; SPBA/CS: 0.395; PW/CS: 1.145.

Head and mesosoma brown, with yellowish appendages; abdomen brown with a yellowish macule on the base of the first gastral tergite. Head with reticulated ground sculpture and coarse superimposed longitudinal striae. Scutum longitudinally striated, without median shiny region. Scutellum with a median smooth and shiny region, sides longitudinally striated. Propodeal spines well developed. Petiole high and long, with concave anterior face and triangular apex. Subpetiolar process medium-sized. Sides of postpetiole on dorsal view converging posteriorly.

Variability. Some workers (7% of all examined individuals) may exhibit a darker coloration pattern, with black to dark brown head dorsum contrasting with brown mesosoma and dark brown gaster with a basal yellowish macule on the first tergite. The mesosoma declivity preceding propodeal spines may be pronounced (18% of individuals), present but not pronounced (54%) or absent (27%). The absolute length of the propodeal spines may be bigger in the smaller specimens of the colony. The petiolar apex appears rounded instead of truncated in 25% of individuals. A poorly-developed mesopropodeal depression is present in 23% of individuals, while it appears as inconspicuous in the rest. Subpetiolar process may be reduced in smaller specimens (12%).

Etymology. Catalan for star, in reference to the color of the mesosoma in contrast with the dark head and gaster, which resembles a star in the sky.

Comments. T. estel sp. nov. is easily distinguished from any other taxa of the Iberian sordidulus species-complex by the unique combination of bicolored body, long head (mean HL/HWb 1.275), inconspicuous to poorly-developed metanotal groove (mean MGr/CS 0.297%) and longest propodeal spines of the complex (mean SPST/CS 0.313).

The most closely related species to T. estel sp. nov. is T. tergestinus , from Central Europe. The first has much longer head (mean HL/HWb 1.252 vs. 1.206), narrower frontal carina (mean FRS/CS 0.343 vs. 0.361), longer scape (mean SL/CS 0.826 vs. 0.799), inconspicuous to poorly-developed metanotal groove (vs. poorly to well-developed metanotal groove in T. tergestinus ) and longer and more diverging propodeal spines (mean SPST/CS 0.313 vs. 0.276; SPWI/CS 0.342 vs. 0.333). Both species exhibit the same coloration pattern, but T. tergestinus can also show extreme dark forms ( Csősz et al. 2015; Borowiec & Salata 2018). Temnothorax tergestinus has a wide Palearctic distribution from Bulgaria to France, but has not been yet recorded from Iberia. It is unknown whether a contact zone between T. estel sp. nov. and T. tergestinus could exist somewhere in North Iberia or South France.

MGr is probably one of the best discriminant characters between T. estel sp. nov. and T. tergestinus , but it has not been measured for the latter species in this paper. Queens of both taxa appear very similar, and the only available queen of T. estel sp. nov. does not allow a safe separation with the queens of T. tergestinus . Males of the sordidulus species-complex are largely unknown and rarely described, since the external morphology is very variable within the same nest and the study of the genitalia is not routinely used in the genus.

Biology. Mostly unknown. Nests were found at high altitude in rock crevices and once under a plain stone, and populations were located from stony open habitats to semi-open pine forests ( Fig. 4 ). All colonies were monogynous. Nest densities were always low. Two colonies kept in an artificial nest were fed with insects and nectar and produced reproductive individuals in early July. The elongated head may be an adaptation to move into rock crevices and nest in narrow spaces.

Distribution. Known from SE Iberia ( Fig. 5 ).

Figures

FIGURE 2. Head (left) and lateral view (right) of the workers of (A) T. conatensis (Mont-Rebei, Lleida), (B) T. estel sp. nov. (Sierra de Cazorla, Jaén), (C) T. ibericus (Sierra de Javalambre, Teruel), and (D) T. platycephalus (Sierra de Cazorla, Jaén).

FIGURE 3. Head (left) and lateral view (right) of the queen of T. estel sp. nov. Individual from Sierra de Cazorla, Jaén (see “additional studied material” under the T. estel sp. nov. description above).

FIGURE 4. A: Nest of T. estel sp. nov. in a rock crevice in Serra d’Aitana, Alacant. B: Worker of T. platycephalus from Sierra de Cazorla, Jaén. C: big rocks where both T. estel sp. nov. and T. platycephalus establish their nest in Sierra de Cazorla, Jaén. D: general view of the habitat of T. estel sp. nov. in Serra d’Aitana, Alacant.

FIGURE 5. Distribution of the southern species in the sordidulus species-complex, including the French records of T. tergestinus and T. sordidulus. Colors: T. conatensis (dark blue circles), T. estel sp. nov. (gold circles), T. ibericus (purple circles), T. platycephalus (red circles), T. sordidulus (green circle) and T. tergestinus (yellow circle).

FIGURE 6. Typical coloration and morphological appearance of the species in the Iberian sordidulus species-complex. Sculpture of frons (left column) and lateral view of workers (right column); T. conatensis (A), T. estel sp. nov. (B), T. ibericus (C) and T. platycephalus (D).