Lasius illyricus Zimmermann 1935

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 : 71-72

4.4.40 Lasius illyricus Zimmermann 1935

Lasius alienus subsp. illyricus Zimmermann 1935

[type investigation]

Type material: Lectotype worker labelled ” Mt. Petka Dubrovnik YUGOSLAVIA V-1928 S.Zimmerman “, ”type series Lasius alienus illyricus Zimmermann “ (upperside 2nd label), ”unlabelled type Le Tenrant 7.90“(underside 2nd label), ”M.C.Z. CoType 30116“, ” LECTOTYPE desig. by E.O.Wilson “, ”Jan-Jun.2001 MCZ Image Database“; 3 paralectoype workers labelled ” Mt. Petka Dubrovnik YUGOSLAVIA V-1928 S.Zimmerman“, ” Lasius alienus illyricus Zimmermann COTYPE“, ”M.C.Z. CoType 30116“; depository: MCZ Cambridge.

Lasius ponticus Stärcke 1944

Lasius alienus var. pontica Stärcke 1944 [description] Stärcke selected as types for L. ponticus 4 workers from the former syntype series of L. alienobrunneus Forel 1874 collected in Neu Atos (Novy Afron) / Caucasus after he fixed a lectotype of L. alienobrunneus on another pin with 4 specimens from Sierre / Switzerland. Types of L. ponticus were not available but the synonymization proposed here is most probable as L. illyricus is the only species occurring in the terra typica and matching Stärcke‘s description.

All material examined. A total of 39 nest samples with 94 workers were subject to NUMOBAT investigation. These originated from Austria (1 sample), Bulgaria (2), Croatia (1), Georgia (3), Greece (6), Iran (11), Turkey (14) and the Ukraine (1). For details see supplementary information SI1.

Geographicrange. From the Balkans (42.65°N, 18.07°E) over the southern Ukraine, the southern Caucasus and entire Asia Minor east to the eastern Elburs Mountains (36.867°N, 54.933°E). The altitudinal distribution ranges from sea level up to 1900 m.

Biology. There seem to exist no significant differences to Lasius emarginatus in habitat selection. In the sympatric area on the Balkans, both species prefer broadleaved forests, especially Quercus and Platanus forests, but there is some trend of L. illyricus to select more open and drier localities. It may occur in urban areas, in gardens and olive plantations. In regions with dryer macroclimate it is found in very shady woods along streams and in the North Iran it is typical for humid broad-leafed Caspian forest. A flight was observed shortly after sunset. Nest are in soil, under stones or in rotten logs. Zimmermann wrote in the original description of L. illyricus ”...auch fehlt ihnen der L. emarginatus eigentümliche Geruch...“ [”...even so, the peculiar odor of L. emarginatus is lacking...“]. It remains to be checked if this is a constant character or only an ephemeral impression due to the circumstances of observation.

Diagnosis ( Tab. 8 , Figs. 77 –78; key; images in www. AntWeb.org with specimen identifiers CASENT0905686, CASENT0914255):

Absolute size large (CS 991 µm). Head and scape length indices large (CL/CW 900 1.082, SL/CS 900 1.073); postocular distance small, eye and torulo-clypeal distance large (PoOc/CL 900 0.223, EYE/CS 900 0.250, dClAn 900 5.45); terminal segment of maxillary palp long (MP6/ CS 900 0.217). Number of mandibular dents large (MaDe 900 8.58). Pubescence on clypeus very dilute (sqPDCL 900 5.71); frontal pubescence short (PLF 900 22.9). All body parts with much fewer setae than in L. emarginatus but in length very similar (PnHL/CS 900 0.137, GuHL/ CS 900 0.124, nOcc 900 7.8, nGen 900 4.1, nGu 900 4.1, nSc 900 2.1, nHT 900 7.4). Coloration: similar to the light morph of L. emarginatus . Dark morph morphs were so far not observed – the darker, more concolorous pigmentation of the small-sized type specimens is probably due to the positive allometry of yellowish or reddish pigments usually observed in Lasius s.str. species.

Comments. A sample from a Quercus pubescens forest from Leopoldsberg near Vienna is determined with a posterior probability of 0.962 as L. illyricus when run as wild-card in a 2-class LDA with L. emarginatus as alternative hypothesis and this sample is allocated to L. illyricus in any exploratory data analysis tested. There are several Mediterranean floral and faunal elements at Leopoldsberg but the interpretation is of this case is problematic as the nearest known site of L. illyricus is 600 km south. In the North Iran, L. illyricus occurs in sympatry and syntopic with L. persicus sp. nov. – a species with a very similar pigmentation but strongly deviating structural characters (for morphological differences see there).

Figures

Figs. 77 and 78: Lasius illyricus; CASENT0914255, photo M. Esposito