The genus Grzegorzekia Edwards (Diptera: Mycetophilidae) revisited: molecular phylogeny and description of four new species

Abstract

The genus Grzegorzekia Edwards, 1941 (Diptera: Mycetophilidae: Gnoristinae) is revised based on newly assembled material from Europe, the Nearctic, and the Oriental region, complemented by molecular data (COI, 16S, 28S). Four new species are described and illustrated: Grzegorzekia pseudocollaris Kurina, Ševčík & Kjaerandsen sp. nov. (Czech Republic, Slovakia, Italy), G. bruneiensis Kurina & Ševčík sp. nov. (Brunei Darussalam), G. taiwanica Kurina & Ševčík sp. nov. (Taiwan), and G. canadensis Kurina & Kjaerandsen sp. nov. (Canada: British Columbia, Alberta). All previously known European species are re-illustrated for comparison, and a revised key to the world species is provided. Diagnostic characters of the genus are confirmed, including the secondary loss of the male gonostylus and the presence of complex, bipartite gonocoxites bearing posterior combs of spines. Molecular data largely corroborate morphospecies boundaries, although G. canadensis comprises two COI BINs with low divergence (2.12%), and G. taiwanica shows pronounced COI divergence despite minimal variation in 16S and 28S. With these additions, Grzegorzekia now comprises nine described species distributed across the Holarctic and Oriental regions. New country records are provided for G. hungarica Papp & Ševčík, 2007 and G. bushyae Chandler, 2015.