Nemoura sahlbergi Morton 1896

Nemoura sahlbergi Morton, 1896

(Figs. 53‒84)

http://lsid.speciesfile.org/urn:lsid: Plecoptera.speciesfile.org: TaxonName:6326

Nemoura sahlbergi Morton 1896:56.

Holotype ♂, Type locality – Utsjoki, Lake Enara, Finland

Nemoura sahlbergi: Claassen 1940:63

Nemoura trispinosa: Ricker 1944:177. In part

Nemoura sahlbergi: Brinck 1952:104

Nemoura sahlbergi: Zhiltzova 1964:187

Nemoura sahlbergi: Meinander 1965:17

Nemoura sahlbergi: Illies 1966:212.

Nemoura rickeri Jewett, 1971:190. Type locality – Cache Creek, 19 mi E Eureka, Glenn Highway, Alaska. New synonym (Paratype ♂ examined) Nemoura sahlbergi: Lillehammer 1972b:157

Nemoura sahlbergi: Benedetto 1973:20

Nemoura sahlbergi: Zwick 1973a:340

Nemoura sahlbergi problematica: Zwick 1973b:162. Type locality – Diamond Range, Kangwon Province, People’s Republic of Korea. Nomen dubium Zwick 2010

Nemoura sahlbergi: Lillehammer 1974a:85

Nemoura rickeri: Dosdall & Lehmkuhl 1979:34 Nemoura rickeri: Stewart & Oswood 2006:78 Distribution. Canada: MB, NT, NU, SK, YK. Europe: Baltic States, Finland, Norway, Sweden. Mongolia. Russia East, Russia North. USA: AK (DeWalt et al. 2018).

Diagnosis.

Cercus. Highly variable. Male cerci are sclerotized laterally and terminate in either one (Figs. 54–57, 59) or two (Figs. 53, 58, 60) produced, curved spines that vary in length, curvature, and degree of tapering, plus a third unit (= outer spine) that tapers little and is typically crenulated distally.

Epiproct. Males exhibit consistency with epiproct shape and characteristics across the Holarctic with only minor differences between individuals. In lateral aspect, the basal cushion occupies the anterior ca. ½ and is separated from the dorsal sclerite by smooth lateral areas (Figs. 61–68). The lateral areas are consistently recurved slightly over the distal medial portion of the basal cushion. The dorsal sclerite is open apically, exposing paired, rounded apical prongs bearing scale-like ridges, terminating laterally into one or two stout, grooved lateral spines (Figs. 69–76). The apical prongs are positioned either ca. parallel (Figs. 82, 84) or ca. diagonal to the ridges (Figs. 77–81, 83).

Comments. The synonymy of N. rickeri with N. sahlbergi has been suggested previously (e.g. Lillehammer 1972b; Boumans & Brittain 2012). Jewett (1971) noted in his description of N. rickeri that this species “…is similar to the rare northern European Nemoura sahlbergi …”. Lillehammer (1972a, his Fig. 29.4) illustrated several different cercal forms from Norway, showing variability in the curved and outer spines. The epiproct apical prongs studied herein from the Northwest Territories (Fig. 78), Alaska (Fig. 80), Norway (Fig. 82), and Mongolia (Fig. 84) are consistent with illustrations or images in Lillehammer (1972a, his Fig. 31.3; Norway), Boumans (2011, his Fig. 2; Norway) and Judson & Nelson (2012, their Fig. 187; Mongolia).

Geographic notes. Holarctic: Scandinavia east across Asia; in North America from Alaska east to Nunavut and Manitoba. South in Europe to Latvia and in eastern Asia south to Mongolia and far eastern Siberia. South in North America to the treeline in the Saskatchewan River Basin in Manitoba and Saskatchewan. Additional notable references include Rauser (1968), Lillehammer (1972a, 1974, 1985, 1988), Burton (1984), Teslenko & Bazova (2009), Zhou et al. (2010), Zwick (2010), Boumans (2011), Boumans & Brittain (2012), and Judson & Nelson (2012).