The tiny Elateridae genus Zorochros (Elateridae; Negastriinae) consists of around 140 species worldwide with the greatest diversity found in the Palaearctic and Oriental biogeographic regions (Han et al. 2015). Species in the genus are usually found living under stones and pebbles beside rivers (Schimmel & Tarnawski 2012) but have also been collected from lake shore gravel (Hume Douglas, pers. comm.). North America has six species in the genus Zorochros (Johnson & Wells 2021) while in Canada, three species have been reported. British Columbia has two species, Z. caurinus (Horn) and Z. dispersus (Horn), while in the eastern provinces Z. melsheimeri (Horn) has been reported from New Brunswick, Quebec, and Nova Scotia (Majka & Johnson 2008, Johnson & Wells 2021, Bousquet et al. 2013).
During examination of the unidentified Elateridae at the Spencer Entomological Collection at the University of British Columbia, the author found a specimen of Z. melsheimeri collected from Ontario (Figure). Label Data (“CANADA, Ontario/ York R.M., Markham/ Little Rouge Creek./ May 21, 1988./ Coll. Brian Harrison”; second label; “Splashing sand, gravel/ & clay banks of creek.”) shows this to be a substantial range extension to the west for this species in Canada.
Zorochros is distinguished within the Negastriinae by the traits outlined in Stibick (1971) and include small body size (2-5 mm) with an arched, convex and granulate pronotum and sutures on both the edge of the hypomeron and prosternum (often called “double prosternal sutures”), which are excavated in some species. In eastern North America, these characters combined with body size 2-3 mm, both fine (small) and coarse (larger) punctures on the pronotum, a long pronotal hind angle carina that extends anteriorly for ½ or ¾ of the pronotum, and the elytra with a humeral and subapical yellow spot distinguish this species from other Negastriinae (Stibick 1991). Horn (1891) distinguished Z. melsheimeri from the very similar western Z. caurinus by the paler antennae and more distinct elytral markings. The antennae colouration difference appears to hold between the species and the aedeagus of Z. melsheimeri is more rounded and less elongate compared to Z. caurinus. The differing number of visible sternites with a central tubercle (reported as one in Z. melsheimeri and two in Z. caurinus) does not appear consistent for every male as the author has seen a Z. caurinus with apparently only one collected from British Columbia.
The author would like to thank Karen Needham the curator of the Spencer Entomological Collection for access to the collection. Thanks also to Trevor and Chloe van Loon for donating specimen of Zorochros caurinus. Thanks to Hume Douglas for many useful comments and Sable Gilmore for proofreading the manuscript. Funding from the Entomological Society of Canada as part of the 2021 Bert and John Carr Award was used to visit the Spencer Entomological Collection.
Figure. Dorsal and ventral habitus of Zorochros melsheimeri (Specimen SEM-UBC COL-34755).
