Temnothorax alienus, Schulz, A., Heinze, J. & Pusch, K., 2007

Schulz, A., Heinze, J. & Pusch, K., 2007, Description of two new Temnothorax species (Hymenoptera: Formicidae) from Italy., Zootaxa 1471, pp. 1-14 : 3-12

Temnothorax alienus nov. spec.

(Figs. 2, 3, 22, 26, 28, 29)

Holotype worker. ITALY, Campania, near Tortora, N. Sapri, Parco Nazionale del Cilento , 39°57.879'N 15°48.809'E, 633 m.a.s.l. , 28.iv.2004 (Leg. K. Pusch, C. Wanke, J. Beibl, P. D'Ettorre) [ SMNK].

Paratypes. 12 workers and 4 gynes, same data as holotype [ MHNG, MCSN, PCAS, SMNG]; 10 workers, ITALY, Campania, near Carpaccio, N. of Agropoli & Paestum, Mte. Vesole, Parco Nazionale del Cilento, 730 m.a.s.l. , 27.iv.2004 (Leg. K. Pusch, C. Wanke, J. Beibl, P. D'Ettorre) [ MHNG, MCSN, PCAS, SMNG].

Etymology. From the Latin word “alienus”, meaning “foreigner” or “alien”, referring to the unique combination of characters, which is found only in a small number of other western Palaearctic Temnothorax species.

Description of worker. Measurements and indices (n=16): HL [0.684] 0.67±0.03 (0.58-0.71), HW [0.580] 0.58±0.03 (0.50-0.63), SL [0.475] 0.48±0.03 (0.43-0.53), FCD [0.220] 0.22±0.02 (0.18-0.24), ML [0.791] 0.77±0.05 (0.67-0.85), MW [0.390] 0.39±0.03 (0.32-0.46), PSL [0.095] 0.09±0.01 (0.07-0.11), PEL [0.238] 0.24±0.02 (0.21-0.27), PEW [0.171] 0.18±0.02 (0.15-0.21), PEH [0.238] 0.23±0.02 (0.21-0.27), PHD [0.090] 0.09±0.01 (0.07-0.11), PPL [0.162] 0.16±0.02 (0.13-0.18), PPW [0.238] 0.23±0.02 (0.20-0.26), HS 0.63±0.03 (0.54-0.67), HW/HL 0.86±0.03 (0.83-0.97), SL/HS 0.77±0.03 (0.70-0.82), FCD/HS 0.34±0.02 (0.31-0.36), MW/ML 0.50±0.03 (0.48-0.63), PSL/ML 0.11±0.01 (0.09-0.13), PEH/PEL 0.98±0.05 (0.91-1.08), PEW/PEL 0.74±0.07 (0.68-0.90), PHD/PEW 0.48±0.07 (0.35-0.56), PPL/PPW 0.72±0.06 (0.64-0.79), PEW/PPW 0.76±0.08 (0.71-0.97).

Head narrower anterior to eyes than posteriorly. Margins of head posterior to eyes weakly convex, vertexal corners evenly rounded, posterior margin of vertex linear. Frontal triangle somewhat impressed but not clearly demarcated. Frontal carinae narrow and short, strongly divergent posteriorly. Mesosoma with dorsal profile evenly and weakly convex, without metanotal groove. Propodeal spines broadly attached, nearly triangular, acute, slightly pointed upward and slightly divergent. Petiole subsessile, its anterior face straight or only slightly concave, node triangular with rounded apex. Posterior face weakly convex or straight, sloping downwards nearly at the same angle as the anterior face. Anterior subpetiolar process large, slightly longer than broad at the base. In dorsal view, petiole with weakly convex to straight sides at midlength, strongly converging anteriorly. In dorsocaudal view the node apex is relatively narrow with a straight dorsal margin. Postpetiole in lateral profile more or less evenly rounded. In dorsal view the postpetiole is subrectangular with weakly rounded corners, slightly broader anteriorly, sides are straight and nearly parallel.

Mandibles very finely irregularly longitudinally striate, sublucid. Frontal triangle smooth with 1-2 shallow micro-rugulae. Clypeus medially lucid, without a coarse median carina, but with some paramedian striae running half way from anterior to posterior clypeal border. Scapes faintly striate to very finely granulate. Frons with a narrow medial unsculptured and lucid part, other surfaces irregularly and divergently rugose with anastomoses. Interspaces between rugae densely reticulate. Posterior frons reticulate with isolated superficial rugae. Genae, surface around the eyes and vertex irregularly rugose to striate, with densely reticulate interstices. Surface posterior to eyes with semicircular rugulae. Ventral surface of head laterally striate, medially smooth. Entire mesosoma irregularly and densely rugose to rugoreticulate, dorsal median surface of mesonotum alveolate. Space between the propodeal spines and entire petiole and postpetiole reticulate. Petiolar node with some fine rugae superimposed on the reticulum. Gaster lucid. Colour entirely yellowish-orange, appendages with same colour, without darker antennal club. Up to 2/3 of posterior portion of first gastral tergite dull orange-brown. Standing pilosity of head, mesosoma and gaster of medium size, transparent, with blunt tips.

Some specimens have stronger medial carinae on the clypeus, the head may be slightly darker than the mesosoma, the distal antennal club may be slightly darker than the rest of the funiculus, the femur may be darker, the gaster may be mainly brownish, with a more or less extended yellow orange spot on the anteriormost portion of the first gastral tergite. The sculpture may be coarser in general, the frons may be entirely reticulate.

Description of gyne. Measurements and indices (n=4): HL 0.74±0.03 (0.73-0.79), HW 0.69±0.03 (0.66- 0.73), SL 0.52±0.02 (0.50-0.54), ED 0.21±0.01 (0.19-0.22), MW 0.77±0.02 (0.75-0.80), PSL 0.10±0.01 (0.09-0.11), PEL 0.30±0.01 (0.29-0.32), PEW 0.23±0.01 (0.22-0.25), PHD 0.11±0.01 (0.10-0.11), PPL 0.23±0.01 (0.22-0.24), PPW 0.31±0.01 (0.30-0.31), ML 1.19±0.04 (1.15-1.24), PEH 0.30±0.01 (0.28-0.31), HS 0.72±0.03 (0.69-0.76), SL/HS 0.72.0±0.01 (0.71-0.73), ED/HS 0.29±0.01 (0.26-0.30), HW/HL 0.93±0.01 (0.92-0.94), MW/ML 0.65±0.01 (0.63-0.66), PSL/ML 0.08±0.01 (0.07-0.09), PEH/PEL 0.97±0.06 (0.87-1.03), PEW/PEL 0.77±0.04 (0.72-0.82), PHD/PEW 0.34±0.02 (0.32-0.36), PPL/PPW 0.74±0.03 (0.70-0.76), PEW/PPW 0.76±0.02 (0.75-0.79), PEL/ML 0.28±0.04 (0.25-0.34).

Head relatively large with weakly convex and convergent genae, rounded vertexal corners and slightly convex anterior clypeus margin. Compound eyes relatively small. Mesosoma short, relatively high and robust, with straight dorsal margin, and distinct pronotal corners. Scutellum broader than long, posterior margin of it semicircular. Propodeal spines short, broadly attached and triangular, with pointed tips, posteriorly oriented. In dorsal view the spines are linear and parallel-sided. Petiole subsessile, with general shape as described for workers. Postpetiole shaped as in workers.

Mandibles faintly longitudinally striate, sublucid. Frontal triangle unsculptured and lucid. Clypeus medially lucid, without a coarse median carina, but with some paramedian carinae, with lucid interstices. Scapes faintly striate, or granulate. Frons striate to carinate, with unsculptured and lucid interstices. Other parts of head dorsum more strongly longitudinally carinate to irregularly rugose, with lucid interstices. Anterior surface of pronotum reticulate, other parts broad-meshed rugose with shining interstices. Mesonotal dorsum with a few longitudinal, nearly invisible carinae, mainly shining. Scutellum lucid, laterad with 2-3 very fine striae on each side. Dorsum of propodeum transversely and diffusely carinate, between and below the spines transversely reticulo-striate. Anepisternum and other lateral parts of mesosoma irregularly and shallowly rugo-striate, with shining interstices. Petiole and postpetiole dorsally rugoreticulate, ventrally reticulate, subopaque. Bicoloured, mainly orange with equally coloured or paler appendages, without darker antennal clubs. Genae, dorsum of head, two lateral small spots of mesonotum, 50% of scutellum, and 2/3 of first gastral tergite darker coloured, testaceus to brownish. Standing pilosity as described in workers.

The male is unknown.

Differential diagnosis. Workers of Temnothorax alienus show the typical nylanderi / parvulus-like petiolar shape (Fig. 6 & 7), but differ from the latter in lacking a metanotal impression or groove. The colour of T. alienus is uniformly light yellow-orange, with only a slightly darker broad band on the first gastral tergite. Other Italian Temnothorax are dark brown to black, or have distinctly darker antennal clubs, or if yellow, they have a shining surface.

Other species that are similar to Temnothorax alienus and lack a metanotal groove are T. tianshanicus (Tarbinsky 1976), T. satunini (Ruzsky , 1902), an unidentified species from Morocco, T. luteus (Forel 1874), T. rabaudi (Bondroit , 1918), and T. italicus (Consani & Zangheri , 1952). The central Asian T. tianshanicus has longer scapes, broader head, and shorter propodeal spines than T. alienus . The head dorsum of T. tianshanicus is more shining. In addition, T. tianshanicus sometimes has a faint metanotal depression. Other characters are similar, thus T. tianshanicus is morphologically the closest to T. alienus .

Temnothorax satunini (Fig. 4 & 5), a species from southern to eastern Turkey and Caucasus, is also morphologically similar, but differs in the following characters: narrower and shining, nearly unsculptured head; yellow colour without darker gaster, and often distinctly shorter propodeal spines (PSL/ML <0.07).

An unidentified Temnothorax species from Morocco (PCAS sp. 27 “Morocco” ) has distinctly longer scapes, a lower, narrower petiole, and a faint metanotal depression. Additionally, the petiole is truncated and pedunculate. Sculpture and colour are similar to T. alienus .

Another lighter coloured species with slightly convex or straight mesosomal dorsum is Temnothorax luteus s.l., which is distinguishable from T. alienus by longer propodeal spines, broader head, longer scapes, and the distinctly lower, pedunculate and narrower petiole. Sculpture characters are similar to T. alienus , but in T. luteus the whole gaster is yellowish coloured. The taxonomic situation of T. luteus is not clear yet; one can split the taxon into two or more species.

The two arboreal species Temnothorax rabaudi and T. italicus (Fig. 10 & 11) are similar in the shape of petiole and mesosoma, and might be confused with T. alienus . However, T. rabaudi and T. italicus differ morphometrically in the length of propodeal spines, and the petioles of both species are distinctly lower and more triangular. The petiolar node apex is more rounded in lateral view, with a straight anterior face. The sculpture of head is more heavily reticulate in both species.

Species that have a metanotal groove but otherwise resemble Temnothorax alienus are T. lichtensteini (Bondroit , 1918), T. nylanderi (Foerster , 1850), T. crassispinus (Karawajev , 1926), T. parvulus, (Schenck 1850) and T. flavicornis (Emery 1870).

Temnothorax lichtensteini (Fig. 8 & 9) workers can easily be distinguished from T. alienus by their very long and curved propodeal spines, the pedunculate petiole with a more rounded or truncated node, the distinct metanotal groove, and the denser sculpture of the head and other parts of the body. Also T. lichtensteini is smaller. Sometimes the colour is identical to T. alienus , but it is usually darker.

Temnothorax nylanderi can be distinguished from T. alienus by its longer propodeal spines and more widely separated frontal carinae. T. nylanderi (Fig. 6 & 7) and T. crassispinus workers are darker, with brownish head and mainly dark brown gaster. They can be distinguished from T. alienus by their distinct metanotal groove, more truncated petiolar node, and evident fine and dense parallel striae on the frons. Sometimes the metanotal groove is less visible or rarely absent in T. lichtensteini , T. nylanderi , and T. crassispinus .

Temnothorax parvulus has distinctly longer propodeal spines, a deep metanotal groove, a smaller head, and gradually narrower frontal carinae. In addition, T. parvulus has a less coarse, mainly reticulate sculpture, and a uniform pale yellow colour. T. parvulus is rarely found in south Italy.

Temnothorax flavicornis is more common, but is easily differentiated by its 11-jointed antenna, coarser head sculpture, longer propodeal spines, and lower petiole.

The gynes of Temnothorax alienus are morphologically similar to T. parvulus or a pale T. nylanderi (Fig. 30 & 31). To distinguish gynes of T. alienus from other Temnothorax species is more difficult than in workers.

Compared to Temnothorax alienus , gynes of T. tianshanicus are distinctly smaller, have longer scapes, a narrower head and petiole, a different petiole shape, and a darker colour. T. satunini differs in the shorter propodeal spines, in shorter and narrower head, and narrower mesosoma, but sculpture and colour are equal. In T. luteus the scapes and propodeal spines are longer, and the petiole is pedunculate and distinctly lower. Nearly the whole mesonotum and scutellum is strongly longitudinally rugose, whereas in T. alienus the surface is mainly unsculptured and shiny. In southern Italy, T. luteus s.l. is brownish and strongly sculptured. Gynes of T. rabaudi and T. italicus have tooth-like propodeal spines and a distinctly lower petiole. In both species the head is densely reticulate. Gynes of T. lichtensteini are dark ferrugineous to brown, distinctly smaller, with larger eyes, and longer propodeal spines. T. nylanderi has a narrower petiole in comparison with the postpetiole, darker head, and the same striation of firons as described in workers. T. crassispinus has distinctly longer propodeal spines. Sculpture and colour are similar to T. nylanderi , but T. crassispinus is generally darker than T. alienus and T. nylanderi . The gyne of T. parvulus has a smaller head, larger eyes, longer propodeal spines, and a narrower petiole in comparison with the postpetiole. The colour of T. parvulus is sometimes uniformly yellowish-testaceous including the gaster, in contrast to the more ferrugineous gynes of T. alienus , but usually T. parvulus has brownish coloured gynes. T. parvulus also has a more pedunculate petiole than T. alienus , yet they are very similar and most safely distinguished by morphometric characters.

Comments. Some of the Temnothorax alienus nests were collected in a forest with Quercus and Laurus trees, at the base of a hill. The ground was covered with rocks and ivy. Nests were located in dead sticks on the ground. A second locality where specimens were collected had sparse vegetation with scattered Castanea and Corylus trees.

An unpublished cytochrome oxidase (CO 1) analysis (Pusch et al) supports the hypothesis that T. alienus is not related to the T. nylanderi / parvulus complex, but is phylogenetically closer to T. unifaciatus or T. luteus .