Lasius emarginatus (Olivier 1791)

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 : 70-71

4.4.39 Lasius emarginatus (Olivier 1791)

Formica emarginata Olivier 1791 [description]

Type specimens are assumed to be lost but Olivier‘s description of specimens found in the Provence allows the following conclusions. The absolute length of males (”deux lignes“ = 4.5 mm) and of gynes (”pres de quatre lignes“ = nearly 9.0 mm) and petiole shape indicate a Lasius and exclude other genera of Formicinae occurring in this particular region. The rectangular, emarginate petiole scale, the dark reddish brown head, the lighter reddish brown ventral part of the mesosoma compared to its dark reddish-brown dorsal part, and the light (not infuscated!) wings in the gyne exclude species of the subgenus Chthonolasius with rectangular scales. The nuptial flight in the evening by the end of June is another reported trait. All these statements multiply to a fair probability that the interpretation of Formica emarginata applied by the myrmecologists during the last 150 years was correct. As there are four cryptic species close to Lasius emarginatus alone in the Westpalaearctic, a neotype fixation in a specimen from France is indicated. Herewith I fix a neotype in the top worker on a pin with three workers labelled ”FRA: Frankreich-06, Prov. Savoie, 12 km E Belley, im Rhonetal, 250 mH, 14.04.1996, 133 Leg. A. Schulz, K. Vock“; depository: SMN Görlitz.

Lasius brunneoemarginatus Forel 1874 .

Lasius emarginatus var. brunneoemarginatus Forel 1874 [description]

The full text of Forel‘s description is: ” L. brunneoemarginatus , ou plutot emarginatus brunneoides . Formes de l‘ emarginatus plus claires et moins poilues, vivant sous l‘écorce des arbres.“ and later, on page 217, he stated as collecting localities Lugano and Zurich. I investigated 6 specimens in MHN Genève which carry a printed ” Typus “ label and ”L. brunneo emarginatus Forel Crimée “ and ”ANTWEB CASENT 0911045“. According to disagreement with the published type localities these specimens cannot be considered as types. Furthermore, there is some doubt if the young Forel, who had little contacts to foreign collectors in 1873 has seen specimens from the Crimea so early. According to Ivan Löbl (former curator in MHN Genève) and the deceased former curator of NHM Basel, Walter Wittmer, Forel‘s wife placed printed type labels to many specimens in the collection after Forel‘s death and probably Forel himself has made this error in his later life. The original handwritten label of Forel does not contain an indication of a type status. The synonymization of L. brunneoemarginatus with L. emarginatus as it is stated here is based on the fact that the latter is the only species of the Lasius emarginatus complex occurring in Lugano or Zurich.

Lasius brunneoides Forel 1874

Lasius emarginatus var. brunneoides Forel 1874

[description]

I agree with Wilson (1955) that Lasius brunneoides is an objective synonym of L. brunneoemarginatus because Forel applied two names on the same descriptive information.

All material examined. A total of 61 nest samples with 154 workers were subject to NUMOBAT investigation. These originated from Austria (6 samples), Bosnia (1), Bulgaria (3), Croatia (4), Czechia (2), England (1), France (3), Germany (13), Greece (17), Israel (1), Italy (7), Slovakia (1), Switzerland (1), and the Ukraine (1). For details see supplementary information SI1.

Geographic range. Only European , meridional to south temperate. From S England and France across Central Europe to the Ukraine; Iberia, Apennine and entire Balkans south to 37°N. A single, extremely isolated finding from Israel (31.798°N, 35.146°E, leg. Besuchet & Löbl 1985.04.30) is interpreted here as anthropogenous introduction from Europe. The northern distributional limit in Central Europe was at 52.5°N in 1980, here planar to submontane, in Vorarlberg up to 600 m and in N Tyrol up to 1200 m. In Greece at 40°N ascending to 1700 m. Significant northern range expansion since 1980 particularly in W Europe: after the first finding in 1983 it has colonized entire Belgium, first records in the Netherlands in 1996 and in S England in 2006. In 2017, 13 sites were known in S England and 7 in the Netherlands with a northern range border at 52.6°N. There is a large geographic overlap area with the sister species L. illyricus in the Balkans and south Ukraine.

Biology. See Seifert (2018).

Diagnosis ( Tab. 8 , Figs. 75 –76; key; images in www. AntWeb.org with specimen identifiers CASENT0172762, CASENT0179933, CASENT0280445):

Absolute size rather large (CS 962 µm). Head and scape length indices large (CL/CW 900 1.085, SL/CS 900 1.067); postocular distance small, eye and torulo-clypeal distance large (PoOc/CL 900 0.217, EYE/CS 900 0.253, dClAn 900 5.38); terminal segment of maxillary palp long (MP6/CS 900 0.221). Number of mandibular dents large (MaDe 900 8.76). Pubescence on clypeus dilute (sqPDCL 900 5.14); frontal pubescence short (PLF 900 24.8). All body parts with standing setae of medium length, (PnHL/ CS 900 0.139, GuHL/CS 900 0.126, nOcc 900 12.2, nGen 900 6.5, nGu 900 6.8, nSc 900 10.4, nHT 900 18.1). The propodeal dome is (as in Lasius illyricus , L. tebessae and L. maltaeus sp. nov.) higher than in usually seen in Lasius s.str. Coloration: Two color morphs occur. The light morph has head, coxae, femora and tibiae medium reddish-brown to dark brown with a reddish tinge whereas mesosoma, anterior clypeal margin, scape, petiole and tarsae are orange. The dark morph is almost concolorous medium to dark brown, is restricted to the south Balkans and may occur sympatric with the light morph. Attempts to separate the light and dark color morph by exploratory or hypothesis-driven data analyses using the 16 standard NUMOBAT characters failed.

Comments. The Westpalaearctic species of the L. emarginatus complex are characterized by a combination of elongated head, long scape, long maxillary palps, large eyes, large torulo-clypeal distance, short frontal pubescence and the gular setae not being much shorter or equal in length to pronotal setae ( Tab. 8 ). The only species of this complex occurring sympatric with L. emarginatus is L. illyricus . The mean classification errors for 52 and 39 samples of L. emarginatus and L. illyricus respectively, in which all standard NUMOBAT characters have been recorded, were 3.3% in NC-Ward, 2.2% in NC-part.hclust, 0% in NC-part. kmeans and 0% in NC-NMDS.kmeans. A mean error rate of 1.4% relative to the controlling discriminant function is a good confirmation of heterospecificity according to the GAGE species concept. The classification error by the LDA on the individual level was 2.2% for 232 workers of both species. For separation from the allopatric species L. maltaeus sp. nov. and L. tebessae see there.

Figures

Figs. 75 and 76: Lasius emarginatus