Revision of Nearctic Dasysyrphus Enderlein (Diptera: Syrphidae).

Dasysyrphus Enderlein (Diptera: Syrphidae) has posed taxonomic challenges to researchers in the past, primarily due to their lack of interspecific diagnostic characters. In the present study, DNA data (mitochondrial cytochrome c oxidase sub-unit I­COI) were combined with morphology to help delimit species. This led to two species being resurrected from synonymy (D. laticaudus and D. pacificus) and the discovery of one new species (D. occidualis sp. nov.). An additional new species was described based on morphology alone (D. richardi sp. nov.), as the specimens were too old to obtain COI. Part of the taxonomic challenge presented by this group arises from missing type specimens. Neotypes are designated here for D. pauxillus and D. pinastri to bring stability to these names. An illustrated key to 13 Nearctic species is presented, along with descriptions, maps and supplementary data. A phylogeny based on COI is also presented and discussed.

New Syrphidae (Diptera) of North-eastern North America.

BACKGROUND: This paper describes 11 of 18 new species recognised in the recent book, "Field Guide to the Flower Flies of Northeastern North America". Four species are omitted as they need to be described in the context of a revision (three Cheilosia and a Palpada species) and three other species (one Neoascia and two Xylota) will be described by F. Christian Thompson in a planned publication. Six of the new species have been recognised for decades and were treated by J. Richard Vockeroth in unpublished notes or by Thompson in his unpublished but widely distributed "A conspectus of the flower flies (Diptera: Syrphidae) of the Nearctic Region". Five of the 11 species were discovered during the preparation of the Field Guide. Eight of the 11 have DNA barcodes available that support the morphology. NEW INFORMATION: New species treated in this paper include: Anasimyia diffusa Locke, Skevington and Vockeroth (Smooth-legged Swamp Fly), Anasimyia matutina Locke, Skevington and Vockeroth (Small-spotted Swamp Fly), Brachyopa caesariata Moran and Skevington (Plain-winged Sapeater), Brachyopa cummingi Moran and Skevington (Somber Sapeater), Hammerschmidtia sedmani Vockeroth, Moran and Skevington (Pale-bristled Logsitter), Microdon (Microdon) scauros Skevington and Locke (Big-footed Ant Fly), Mixogaster fattigi Locke, Skevington and Greene (Fattig's Ant Fly), Neoascia guttata Skevington and Moran (Spotted Fen Fly), Orthonevra feei Moran and Skevington (Fee's Mucksucker), Psilota klymkoi Locke, Young and Skevington (Black Haireye) and Trichopsomyia litoralis Vockeroth and Young (Coastal Psyllid-killer). Common names follow the "Field Guide to the Flower Flies of Northeastern North America" (Skevington et al. 2019).

Name-bearing type specimens in the Canadian National Collection of Insects, Arachnids Nematodes (CNC): Blattodea, Dermaptera, Notoptera, Mecoptera, Megaloptera, Myriapoda, Neuroptera, Odonata, Orthoptera, Phthiraptera, Pseudoscorpiones, Psocoptera, Raphidioptera Siphonaptera.

A catalogue is provided for the name-bearing types of most of the less diverse arthropod groups deposited in the Canadian National Collection of Insects, Arachnids Nematodes (CNC). There are 90 name-bearing types of Myriapoda [Chilopoda (3 types), Diplopoda (2)], Arachnida [Pseudoscorpiones (1)], and Insecta [Blattodea (1), Dermaptera (1), Notoptera (3), Mecoptera (3), Megaloptera (2), Neuroptera (11), Odonata (2), Orthoptera (5), Phthiraptera (2), Psocoptera (10), Raphidioptera (1) and Siphonaptera (43)]. Three myriapod syntypes are represented by an unknown number of specimens. Holotypes for Plesiorobius canadensis Klimaszewski Kevan (Neuroptera) and Sphaeropsocoides canadensis Grimaldi Engel (Psocoptera) are amber-preserved fossils. Portions of the holotype of Chaetospania assamensis Sakai are considered lost, as are an unknown number of syntype specimens for the centipede species Ethopolys alaskanus Chamberlin and E. integer Chamberlin. Collembola types were treated in Stebaeva et al. (2016), and Araneae, Ephemeroptera, Plecoptera and Trichoptera will be treated in future catalogues, completing inventories for the orders without associated research staff in the CNC. Definitions of relevant type specimens are provided, as is a preliminary summary of all 16,710 name-bearing type specimens held by the CNC, including those of the more diverse orders for which there are associated research staff: Nematoda, Acari, Coleoptera, Diptera, Hemiptera/Thysanoptera, Hymenoptera and Lepidoptera.