Lasius excavatus, Seifert, 2020

Seifert, Bernhard, 2020, A taxonomic revision of the Palaearctic members of the subgenus Lasius s. str. (Hymenoptera, Formicidae), Soil Organisms 92 (1), pp. 15-86 : 48-49

4.4.4 Lasius excavatus sp. nov.

Etymology. The species name refers to the shape of posterior head margin.

Type material. Holotype plus 2 paratype workers labelled ” IRAN: 30.229°N, 55.375°E, Shar-e-babak: Maymand , on trees in garden, 2220 m, O. Paknia 2004.06.11 -169“; 3 paratype workers labelled ” IRAN: 30.900°N, 51.419°E, Sisakht, Kharidun, 2500 m, oak steppe forest, on tree, O. Paknia 2007.07.10 -1727“; all material stored in SMN Görlitz.

All material examined. A total of two nest samples with 6 workers from two localities in the Iran were subject to NUMOBAT investigation. For details see supplementary information SI1.

Geographic range. Only known so far from the two type localities in the highland desert of S Iran at elevations of 2200–2500 m.

Diagnosis ( Tab. 1 , Figs. 7 –8): The low number of mandibular dents (MaDe 900 7.00), the linear profile lines of the dorsum and posterior slope of propodeum, the sharp dorsal crest of petiole scale, the very smooth pubescence on scapes and tibiae, the strongly reduced pilosity, the short pronotal setae (PnHL/CS 900 0.102) and the short frontal pubescence (PLF 900 23.2 µm) place L. excavatus sp. nov. within the Lasius brunneus species complex. The main difference to the three related species L. brunneus , L. silvaticus sp. nov. and L. himalayanus are the longer scape (SL/CS 900 0.974), the shorter postocular index (PoOc/CL 900 0.222) and a suggested excavation of posterior head margin. The coloration is similar to the situation in L. brunneus , yet with two of the six type specimens a little darker.

Biology. The climatic conditions within the highland desert of Iran are harsh due to high aridity, high summer temperatures and very cold winters. The species was found in rare spots with less extreme conditions allowing growth of trees: a light Quercus woodland and a light stand of broad-leafed trees in the ancient settlement of Maymand. L. excavatus sp. nov. appears to be arboricolous and is probably an Iranian endemic.

Comments. None.

Figures

Figs. 7 and 8: Lasius excavatus sp. nov.; holotype