Lasioseius zerconoides Willmann 1954

Notes on Lasioseius zerconoides Willmann, 1954

Willmann (1954: 225) described Lasioseius zerconoides based on 13 females he had collected from under the bark of trees in the former Czechoslovakia (now the Czech Republic). He illustrated the dorsal and ventral idiosoma, some dorsal setae, and the epistome. The poor condition of the specimens he examined undoubtedly did not allow him to describe some important morphological structures in greater detail or accuracy. For example, he described and illustrated the sternal shield with four pairs of setae (st1‒st4) and the ventrianal shield with seven pairs of pre-anal setae (JV1‒JV5, ZV2, and ZV3), and these misleading statements were later adopted by Karg (1971) and Bregetova (1977) for their then modern and still widely used identification keys. Later, Karg (1980) and then also Gwiazdowicz (2007), examining and illustrating the same type specimens of Willmann, found only three pairs of setae on the sternal shield (st1‒st3) and four pairs of pre-anal setae on the ventrianal shield (JV1‒JV3 and ZV2). But unfortunately, like Willmann (1954), they also neglected the specific concave formation of the posterior margin of the sternal shield with its deep notch (desclerotisation), the most important diagnostic feature of several species with reduced sclerotisation of the sternal shield (Mašán & Halliday 2023).

The above circumstances lead to misinterpretation of some morphological characters and misidentification of easily recognisable Willmann species. The sternal areas of all four examined females of the original Willmann type series currently deposited in the the Bavarian State Collection of Zoology in Munich (the slides No. W35/21‒24) are shown in the micrographs in Figs 35‒38. In all photographed specimens, a conspicuous incision on the posterior margin of the sternal shield is more or less pronounced. Such a specific, deeply incised shape of the sternal shield, together with four pairs of pre-anal setae on the ventrianal shield, is typical for only two species of the genus, namely L. ometes (Oudemans, 1903) and L. verruciger Mašán & Halliday, 2023 [for reliable distinguishing characters between them see the identification key of Mašán & Halliday (2023)].

I have not examined the type specimens of L. ometes, described by Oudemans (1903: 100) from the Netherlands, but the available specimens of L. zerconoides are clearly conspecific with the specimens that are commonly and abundantly collected in Europe and that are widely identified as L. ometes. Since I could not find any reliable distinguishing characters in Willmann‘s specimens that would provide a useful basis for establishing a separate species, and all important characters of the type specimens of L. zerconoides are within the range of variation that I found in my own specimens of L. ometes, I relegate L. zerconoides into synonymy with L. ometes.