Diura nanseni

Diura nanseni (Kempny, 1900)

Arctic Springfly http://lsid.speciesfile.org/urn:lsid: Plecoptera.speciesfile.org: TaxonName:927

Figs. 31-45, 74-77

Isogenus nanseni Kempny 1900:90,

type (s) not designated, Northland County (Susundalen, 1♂; Skarmodalen 1♂; Vefsen 1♂; Braendmo, 1♀), Norway

Diura nanseni Brinck 1949:65

Diura nanseni (f. typica) Brinck 1954:199

Diura nanseni Illies 1966: 383, in part

Diura nanseni Zwick 1973:228, in part

Diura nanseni DeWalt et al. 2018, in part

Material examined. Specimens of D. nanseni examined for this study are consistent with previous descriptions and illustrations of this species (Kempny 1900, Klapálek 1912, Bengtsson 1933 (as Dictyopterygella subfissa – vide Brinck 1949), Brinck 1949, 1952, Lillehammer 1974, 1988), Russia; Russian Far East: Amur River Basin, Zeya River Basin, Selemdzh River, near Fevral’sk, V. Teslenko, 14 June 2004. 1♂, 1♀ (RASC); Sweden; Fulufjället National Park, Njupeskär waterfall, P. Brinck, 11 July 1927, 2♂, 4♀ (CHNC). Lu. Lpm. Kvikkjokk (CRN: interpreted as Lule River of Lappmarken region), P. Brinck, 25 June 1944, 1♂, 1♀ (BYU), [CRN laboratory photo voucher D36].

Adult habitus. In life general color dark brown to black (Kempny 1900), when preserved in alcohol coffee or tan brown (Figs 40-45). Head dorsum with a dark brown X-band on frons (Figs. 31, 40); M-line less distinct than that of D. washingtoniana; small oval-shaped light spot near base of the antennae of each side; interocellular area with sub-triangular light spot; vertex and occiput with a transverse, light, median band adjacent to, but separated from, the interocellular spot. Markings on head, pronotum, and meso- and metaeusterna (Figs. 31, 32) similar to those of D. washingtoniana. A complete sternacostal suture (Fig. 32 ss) is present as well. As in D. washingtoniana, only abdominal segments 1 & 2 divided by the pleural membrane of each side into separate terga and sterna.

Male. Body length of D. nanseni (Lillehammer 1974) generally smaller than D. washingtoniana, approximately 0.5 to 0.9X the length of the latter. Macropterous, forewing length (Lillehammer 1974) similar to D. washingtoniana. However, micropterous populations are reported from Norway (Lillehammmer 1974, Saltveit and Brittain 1986) and Mongolia’s Bayanhkongor province (Raušer 1968). In the latter case specimens are likely D. bicaudata as this species has been found in this province (see Material Examined section for D. bicaudata below). Tergum 8 (Fig. 33) with a median line of lightly sclerotized spots; setose but lacking blunt, stout sensilla basiconica. Tergum 9 pattern of sclerotization differs from D. washingtoniana in that the small mesal, shallow, U-shaped area at the hind margin (Fig. 33) is separated by a short distance from the anteriorly located narrow, longitudinal, lightly sclerotized median strip; setose but lacking blunt, stout sensilla basiconica (Figs. 34, 74). Tergum 10 pattern of sclerotization as well as the distribution of setae and blunt, stout sensilla basiconica similar to those exhibited by D. washingtoniana (Fig. 33). Epiproct also absent. Paraproct caudal projections in dorsal and ventral views (Figs. 33, 36, 41, 44) with outer surfaces more convex than those of D. washingoniana; setose with both short as well as long, slender setae; in lateral view (Figs. 34, 35, 42, 45, 75) they resemble a Bowie knife blade in that the apical frontodorsal margins are noticeably ‘clipped out’, terminating in broadly rounded short tips that, unlike those of D. washingtoniana, are not bulbous or so sharply upturned as to appear boot-like.

Female. Body length (Lillehammer 1974) approximately 0.75 to 0.95X the length of D. washingtoniana. Macropterous, forewing length (Lillehammer 1974) similar to D. washingoniana. Subgenital plate shape variable (Figs. 37, 38, 43) (Brinck 1949, Lillehammer 1974); somewhat narrower than that of D. washingtoniana, ca 2.0 – 2.5X wider than long. Spermatheca and vagina similar to those of D. washingtoniana (Fig. 39), spermatheca (s) appears somewhat more elongate, approximately

3.5X longer than wide; spermathecal duct (sd) 0.9X

length of vagina (v); spermatheca and duct bearing accessory glands (ag).

Larva. Originally described by Brinck (1949), other descriptive information provided by Brinck (1952), Saltveit (1978), and Lillehammer (1988). Similar to that of D. washingtoniana , including pronotum lateral margins with few or no spinulae.

Egg. Initially described by Lillehammer (1988, fig. 76) and nearly identical to D. washingtoniana .