Formicoxenus nitidulus (Nylander 1846)

Seifert, Bernhard, 2023, Two new species of Formicoxenus Mayr 1855 and Leptothorax Mayr 1855 from Tibet (Hymenoptera: Formicidae), Soil Organisms 95 (2), pp. 129-142 : 133-135

Formicoxenus nitidulus (Nylander 1846)

Myrmica nitidula Nylander 1846 [type investigation] The species has been described in an ergatoid male from Helsingfors (=Helsinki), leg F.W. Maeklin.

Investigated were two syntypes on different pins. The first is labelled ‘H: fors’, ‘W. Nyland.’, ‘ Mus. Fenn’, ‘ Mus. Zool. H: fors Spec. typ. No. 5072 Myrmica nitidula Nyl. ’ and the second one with equal labels except for ‘... Spec. typ. No. 5073... ’.

Myrmica laeviuscula Foerster 1850 [original description] This taxon has been described from Aachen in a gyne. Types are probably lost but the original description clearly indicates a synonymy with F. nitidulus . Foerster already considered a possible synonymy but decided to describe a new species because his gyne had 11 antennal segments whereas Nylander’s ‘worker’ (in fact an ergatoid male!) was reported to have 12 segments.

Myrmica lucidula F. Smith 1858 [original description] This taxon has been described from Weybridge, Surrey (leg. Waterhouse). The only descriptive statement was that the ants ‘...appear always to inhabit the nest of the wood-ant, never constructing a nest of their own’. As there is in Europe only a single shiny ( ‘ lucidula ’) ant living in nests of Formica rufa group ants, there is little doubt on a synonymy.

Formicoxenus nitidulus var. picea Wasmann 1906

[original description]

This taxon was described from Luxembourg as a very dark (nearly blackish brown) color variant found in a nest of Formica pratensis Retzius 1783 . The synonymy is obvious.

Material examined. Morphometric data were taken in seven samples with 10 workers from Czech Republic, Germany and Finland. For details see supplementary information SI1. The material subjectively inspected is from the whole Westpalaearctic .

Geographic range. Eurosiberian , temperate-boreal. The very wide host spectrum allows continuous distribution from Scotland and France to Russian Far East. In Fennoscandia up to 70°N, in the Alps ascending to 2300 m .

Diagnosis: --Worker ( Figs 6–9 , key). Numeric data given are arithmetic means based on measurement of 10 specimens (for standard deviation, minimum and maximum values see Tab. 1). Rather small size, CS 642 µm. Head much elongated, CL/CW 1.270. Clypeus extended caudad, semiglobular, in dorsal view with a semicircular anterior margin. Posterior margin of head straight. Frons extremely broad ( FRS / CS 0.513). Scape rather short, SL/ CS 0.677. Eye small, EYE / CS 0.186, with long setae ( Fig. 9 ). Dorsal profile of promesonotum and propodeum weakly convex, metanotal depression shallow (MGr/ CS 1.34 %). Spines rather short (SP/ CS 0.143) and not very acute, their bases rather distant ( SPBA / CS 0.324). Petiole with strong anterolateral corners, in profile without peduncle and with a broad subpetiolar lobe. Postpetiolar sternite with a well-developed spine. All surfaces of head, mesosoma, waist and appendages smooth and very shiny, sometimes frontal lobes and genae weakly longitudinally carinulate. Gaster glabrous and with very dilute pubescence. Head, mesosoma, waist, scape, femora and tibiae with scattered and short (PnHL/ CS 0.077) setae, tapering apicad and round in cross-section. Color variable from light yellowish brown to nearly blackish brown .

Taxonomic comments. As a combination of smooth and shiny body surfaces, very broad frons, elongated head and extended semiglobular clypeus not to confuse.

Biology. See the condensed description of life history in Seifert (2018).

Figures

Figure 6–9. Formicoxenus nitidulus; (6) head in dorsal view; (7) lateral view; (8) dorsal view; (9) dorsolateral view on eye. Germany: Altdöbern, 1992.02.09