Sminthurinus lawrencei

van Bezouw, Roel F. H. M., McCulloch, James, Janssens, Frans & Berg, Matty P., 2022, An emended description of Sminthurinus lawrencei Gisin 1963, with notes on the identification of black Sminthurinus species, Soil Organisms 94 (3), pp. 127-138 : 134-135

Sminthurinus lawrencei

Summarizing the identification of newly collected specimens, re-examination of previously collected material vastly increased the number of previously published occurrences for S. lawrencei over those previously recorded in North-Western Europe ( Table 1, Fig. 4 ). Most of these records are from the Netherlands. Additional records supported by collected material originate from Belgium, thus confirming the presence of the species there, too.

The use of the colouration and shape of the inter-ocular vesicles is a trait that was first used since 2015 by the third author, a character to distinguish between the dark Sminthurinus- specieson digital images. By examining the collection material, this character is found to reliably separate the otherwise uniformly black S. lawrencei from S. niger and S. concolor . In S. lawrencei , these white inter-ocular vesicles are small, roundish with three teeth pointing inwards in an adult specimen. This inter-ocular vesicle does not advance beyond ocellus C and the distance between the left and right inter-ocular vesicle is more than twice that of the inter-ocular vesicle diameter ( Fig. 5A ). In S. niger , this white inter-ocular vesicle circumvents most of the upper and posterior sides of the ocular fields, creating a large crescent shape in full-grown adults ( Fig. 5B ). In S. concolor , these inter-ocular vesicles are much larger than in S. lawrencei and are not crescent shaped. The distance between these inter-ocular vesicles is less than twice that of the inter-ocular vesicle diameter and features a single, large anterior indentation ( Fig. 5C ). The listing in table 1 is not exhaustive for images from public images due to the large number of records available, which are nearly always misidentified S. niger . However, several of such photographs were taken from France and Canada, from which S. lawrencei was not previously recorded and these are thus included in the list ( Table 1, Fig. 4 ).

Figures

Figure 4. Distribution of localities of verified records of Sminthurinus lawrencei in Western Europe. The Canadian record is not shown. Circles represent records supported by collection material. The diamond indicates the location of the type locality (Gisin, 1963; United Kingdom). The squares represent literature records.

Figure 5. Habitus features of dark Sminthurinus-species fixed in ethanol. (A) S. lawrencei (material from Belgium), inter-ocular vesicle (i.e. ‘eye brow’) small, distance> 2x eyepatch diameter, (B) S. niger (material from the Netherlands) inter-ocular vesicle circumventing the ocular field, distance inter-ocular vesicle smaller than ocular field (C) S. concolor (material from Yersey Island), inter-ocular vesicle large, with a single indentation, distance <than two 2x inter-ocular vesicle diameter. Images show representative specimens from various locations, collected in 70% ethanol.Arrows point to the inter-ocular vesicular patches.