Abstract
BACKGROUND: The subfamily Gnoristinae is one of the most diverse and taxonomically difficult subfamilies of Mycetophilidae, with new species and genera being described almost every year from various parts of the world. Through inventories of fungus gnats in the Nordic Region and Russia, a genus and species new to science was discovered, yet with links back to an illustration made by the late French entomologist Loïc Matile in the 1980s. DNA barcoding aligned it with yet another species new to science, distributed across Canada and documented through The Barcode of Life Data System (BOLD) by Paul D. N. Hebert and colleagues at the BOLD team. NEW INFORMATION: The new Holarctic genus, Coelosynapha gen. n. is described, consisting of two new species, the Palaearctic Coelosynapha loici sp. n. and the Nearctic Coelosynapha heberti sp. n. DNA-barcodes assign the two new species to distinctly separated (8.27% p-distance) Barcode Index Numbers (BINs) which are most closely aligned to unidentified species of Mycetophilidae from South Australia and Costa Rica on BOLD. The new genus shows morphological characteristics in between the two Holarctic genera Coelosia Winnertz, 1864 and Synapha Meigen, 1818 and further shows affinity to the southern continents genus Austrosynapha Tonnoir, 1929. The Palaearctic Coelosynapha loici sp. n., for which habitat requirements are best documented, is largely restricted to pristine, old-growth conifer (mostly spruce, Picea abies ssp. obovata) forests within the boreal vegetation zone, although it is also recorded from hummock tundra along the Anadyr River in Far East Russia.