Medon ripicola (Kraatz, 1854)

Pentinsaari, Mikko, Anderson, Robert, Borowiec, Lech, Bouchard, Patrice, Brunke, Adam, Douglas, Hume, Smith, Andrew B. T. & Hebert, Paul D. N., 2019, DNA barcodes reveal 63 overlooked species of Canadian beetles (Insecta, Coleoptera), ZooKeys 894, pp. 53-150 : 53

Medon ripicola (Kraatz, 1854) Figure 18

Distribution.

Native to the western Palaearctic region, widespread in Europe and also reported from Algeria, Morocco, Turkey, and Madeira ( Schülke and Smetana 2015). Adventive in the Nearctic region (Nova Scotia, Canada).

Canadian records.

Nova Scotia: Cape Breton Highlands National Park, 10-May-2013 to 21-May-2013 (1 ex, CBG).

Diagnostic information.

Body length: 3.7-4.2 mm. Habitus as in Fig. 18A . Male sternite VII as in Fig. 18C . Aedeagus as in Fig. 18B .

Bionomic notes.

This species is rarely collected in the Palaearctic, with its breeding microhabitat unknown (probably in deeper litter or mammal burrows). In Central Europe, specimens have been collected mostly in wetlands (floodplains, ponds), in flood debris, mole nests, and deeper deciduous leaf litter ( Assing 2012). Palm (1963) wrote that this species was rarely collected in Scandinavia: once in Sweden under pebbles on the seashore and in Denmark under seaweed. Its occasional but typical appearance near water suggests that heavy rains may flood out the breeding microhabitat and deposit the beetles elsewhere (e.g., flood debris). The collection of M. ripicola on northern European seashores suggests a potential mechanism for introduction to the Canadian Maritimes through ocean commerce. The Canadian specimen was collected with a Malaise trap in a riverside forest.

Comments.

A single female voucher from Canada was available for study and, while males would normally be necessary to confirm a positive identification in Medon by morphology, its barcode sequence clustered within the European material of M. ripicola with only two nucleotide sites differing from the nearest European specimen. All similar Palaearctic species that could be confused with M. ripicola ( M. apicalis (Kraatz, 1857), M. brunneus (Erichson, 1839), M. fusculus (Mannerheim, 1830)) are represented in BOLD in separate BIN clusters. The female voucher was also morphologically compared to representatives of all Palaearctic Medon species and was consistent with the body proportions, punctation and color of M. ripicola . As the Nearctic fauna of Medon is unrevised, useful comparisons with North American species are not yet possible. Recognizing this species in the Nearctic region is reliably accomplished, at present, using dissected males or DNA barcoding.

Figures

Figures 17 - 19. 17 Medon apicalis (Kraatz) 17 A habitus 17 B aedeagus, ventral and lateral view, V. Assing 17 C male sternite VII, V. Assing 18 Medon ripicola (Kraatz) 18 A habitus 18 B aedeagus, ventral and lateral view, V. Assing 18 C male sternite VII, V. Assing 19 Pseudomedon obscurellus (Erichson) 19 A habitus 19 B aedeagus, lateral view, V. Assing 19 C male sternite VIII, V. Assing. Scale bars: 1.0 mm (17 A; 18 A; 19 A), 0.2 mm (17 B, C; 18 B, C; 19 B, C).