Lasius lasioides (Emery 1869)

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 : 49-50

4.4.5 Lasius lasioides (Emery 1869)

Prenolepis lasioides Emery 1869 [type investigation]

Type material: Lectotype, an alate gyne, labelled by Mayr ”Neapel Emery“, ”Collect. G.Mayr“, ” L.fumatus m., lasioides m., det. Emery“ and ” lectotype, des. E.O.Wilson“; 1 paralectotype worker labelled by Mayr ”Neapel Col. G.Mayr“, ” L.fumatus m., lasioides m., det. Emery“ and ”Typus“; both specimens in NHM Wien. Emery (1869) produced confusion in naming this species which was described ”from the environs of Napoli“. In the verbal description on page 6 he described the species under the name Prenolepis lasioides and gives a reference to Fig. 3a , but in the caption for Fig. 3a on page 26 he suddenly presents the name Lasius fumatus . Accordingly, L. fumatus is an objective synonym because it refers to the same material

Lasius fusculus (Emery 1869)

Prenolepis fuscula Emery 1869 [original description, investigation of type-compared material]

One worker, deposited in NHM Wien and labelled by Gustav Mayr ”Emery Neapel 1874“, ” Lasius fusculus Emery Neapel “ and ” Lasius fusculus E. det. G.Mayr“ was apparently sent by Emery to Mayr in 1874. Lasius fusculus was described from workers running over a balcony at Portici near Napoli. The rather detailed description of Emery and the fact that there is only one Lasius species in Italy matching this description strongly suggests a synonymy with L. lasioides . Emery reported a minute total length of 2–2.5 mm and only 5–6 mandibular dents which both is typical for nanitic workers of L. lasioides . It appears possible that the specimen sent to Mayr really belongs to original material of L. fusculus as it has MaDe 6.0 and CS 601 µm. The workers of both Lasius lasiodes and L. fusculus Emery had at hand when describing these species were nanitic workers with a reduced number of mandibular dents. The latter character apparently prompted him to allocate both taxa to Prenolepis .

Lasius nigrobrunneus ( Donisthorpe 1926)

Acanthomyops brunneus var. nigrobrunneus Donisthorpe 1926

This taxon was reported by Donisthorpe to occur at Ospedaletti, Bordighera and Monte Nero in N Italy and has been unexplained synonymized by Wilson (1955) and Baroni Urbani (1971) with Lasius brunneus . The complete morphological description of Donisthorpe is ”head quite black, and the rest of the body dark brown; but there are no outstanding hairs on the tibiae“ and he reported to have found the three nests under stones. This information does not suggest an arboricolous ant related to Lasius brunneus but may refer to at least four different species expected to occur in the area: L. alienus , L. paralienus , L. psammophilus , and L. lasioides . There is a worker stored in BMNH London and pictured in antweb.org with specimen identifier CASENT0903216, labelled ”Ospedaletti 6.II. 25.“, ”ex coll. Donisthorpe B.M. 1934-4“ and ” Type “. This type specimens belongs to either L. lasioides or L. alienus . The short pronotal setae and scale shape more strongly suggest a synonymy with L. lasioides which is hypothesized here. The specimen was not directly investigated.

Lasius barbarus Santschi 1931

Lasius alienus var. barbarus Santschi 1931 [type investigation]

The taxon has been first described under the unavailable name Lasius niger lasioides v. barbara Santschi 1921 .

Type material: Lectotype and 3 paralectotypes on the same pin labelled ”Type“, ”Sidiayech 141“, ” Lasius niger st. lasioides Em v. barbara Sants T. Santschi det. 1921“, and ” lectotype uppermost worker desig. by E.O.Wilson “; depository NHM Basel. Three paralectotype workers on one pin labelled ”Sidi Ayech 141“, ”83“, ”MUSEUM PARIS AFRIQUE DU NORD A.THÉRY 1919 1923“, ” Lasius niger st alienus For v. barbarus Sants “; depository MNHN Paris. For synonymization with L. lasioides see under Comments.

All material examined. A total of 106 nest samples with 306 workers were subject to NUMOBAT investigation. These originated from Algeria (4 samples), Cyprus (4), France (14), Greece and Crete (15), Iran (1), Israel (3), Italy (15), Malta (4), Morocco (17), Spain (16), Syria (1), Tunisia (4), Turkey (8). For details see supplementary information SI1.

Geographic range. L. lasioides is a Holomediterranean species – the missing of records from Libya and Egypt are caused by absence of sampling activities. The most southwestern site is in Morocco at 30.8°N, 8.8° W. The northern distributional border runs along 43.5° N in France, 44.6° N in Italy, 40.5°N in Greece and Turkey whereas the easternmost truly Mediterranean site is at 35.6°N, 36.2°E in Syria. The distribution farther east is poorly known. Samples from two sites in the East Anatolian highland (PR_N 502, 39.43°N, 39.88°E, 1800 m; PR_N 460, 38.63°N, 43.45°E, 2300 m) might possibly represent a separate population or even species with special adaptation to wintercold climate. The sample from Ghaemshar / Iran (36.46°N, 52.86°E, 49 m) represents the easternmost known site and raises the question if there is a continuous distribution from Syria and Israel east to the northern Iran. The highest site in the Moroccan Atlas Mountains is at 33.00°N, 5.07°W, 2240 m. It may be expected to have colonized all sufficiently large islands in the Mediterranean Sea which have some tree stands.

Diagnosis ( Tab. 1 , Figs. 9 –10; key; images in www. antWeb.org with specimen identifiers CASENT0906077, CASENT0912293): L. lasioides shows all diagnostic characters of the L. brunneus species complex. It can be separated from its semipatric relatives L. brunneus and L. silvaticus sp. nov. by smaller head width, longer scape and larger torulo-clypeal distance. With all measurements in mm, the discriminant

222.5*dClAn + 29.75*SL – 35.6*CW

is <0.8 in L. brunneus and L. silvaticus sp. nov. but> 0.9 in L. lasioides (error 0% in 288 individuals). Confusion with L. himalayanus is excluded by zoogeography. The potentially sympatric Iranian desert species L. excavatus sp. nov. differs by head shape and coloration. Coloration in L. lasioides : head, mesosoma, gaster, femora and tibiae dark to medium brown; tibio-femoral joint region, scape and (frequently) anterior margin of clypeus pale yellowish-brown.

Biology. Lasius lasioides is apparently dependent from the presence of trees. It inhabits diverse types of broad-leafed or coniferous forest, both such with closed canopies or more open stands, as well as urban areas, gardens, pastures and road sides with at least a few scattered trees. The nests may be found under bark of the trees or on ground in dead logs or under stones. The behavior is similar to L. brunneus : it is fugitive and not aggressive and workers prefer runways in crevices of bark or other surface structures. Development of alates differs throughout the whole geographic range in dependence from latitude and altitude. Eleven observations of alates occurred 30 April – 29 July, ten of these before 8 July.

Comments. The Holomediterranean population of L. lasioides is polymorphic; there is in particular an extreme variance in scape length ( Tab. 1 ). This polymorphism shows a rather clear geographic structuring. Exclusively the long-scaped morph, which corresponds to the types of L. lasioides , was found in Italy and Greece and the islands of Mallorca, Malta, and Sardinia. Only the short-scaped morph, which corresponds to the types of L. barbarus , was found in the Spanish mainland and on Cyprus. Sympatric occurrence of both morphs is observed in Morocco, Algeria, Tunisia, Syria, and Israel. The Iberian short-scaped population and the Italian long-scaped population are in contact in southern France. This structure and a seemingly mutually exclusive occurrence on islands aroused suspicion on heterospecificity of L. lasioides and L. barbarus . However, attempts to show heterospecificity with exploratory data analyses – different forms of NCclustering as well as PCA or TSCA – led to contradictory results. The overall error rate remained clearly above the 4% threshold required by the GAGE species concept.

Figures

Figs. 3 and 4: Lasius silvaticus sp. nov.; holotype

Figs. 9 and 10: Lasius lasioides; CASENT0906077, photo S. Hartman