Oreodytes alaskanus (FALL, 1926)

Fery, H., P. N & Alarie, Y., 2007, Notes on the identity of Oreodytes dauricus (MOTSCHULSKY 1860) and other members of the O. alaskanus-clade (Coleoptera: Dytiscidae), Linzer biologische Beiträge 39 (1), pp. 65-78 : 72

Key to species of the Oreodytes alaskanus -clade

The following key to species is based in part on that given in LARSON et al. (2000: 453). Numbers with an asterisk (*) relate to figures in this work.

1 Male with median lobe in ventral view narrow and subparallel ( Figs 7b , 9b); last but one visible sternum with hind margin straight, lacking a posteromedial lobe. Female with apex of last visible sternum not protruded, but deeply U-shaped in posterior view (Fig. 15). One Palaearctic and one Holarctic species..........................................................2

- Male with median lobe in ventral view broadened subapically and spoon-shaped (Figs 117E*, 117J*); last but one visible sternum with at least a small posteromedial lobe. Female with apex of last visible sternum distinctly protruded and lobed medially (Figs 117C*, 117H*). Nearctic species........................................................................................3

2 Pronotum with posterior angles acute, but moderately produced. Protibia less strongly curved (Figs 11-12). Body shorter (TL: 4.7-5.3 mm). Male median lobe as in Figs 7 a-c. Species known from the Russian Far East, Alaska ( USA), and the Yukon Territory ( Canada).................................................................................. O. dauricus (MOTSCHULSKY)

- Pronotum with posterior angles acute and strongly produced. Protibia strongly curved (Figs 13-14). Body longer (TL: 5.0- 5.7 mm). Male median lobe as in Figs 9a-c. Species known from Mongolia............................................. O. shorti (SHAVERDO & FERY)

3 Male median lobe moderately broadened subapically, its maximum width less than two times its medial width (Fig. 117E*). Female elytron with subapical tooth obtuse, hind margin behind tooth forming an angle of much less than 90° with suture (Fig. 117A*, 117B*). Species known from southern Alaska, Alberta, and Washington ............................ ............................................................................................................. O. alaskanus (FALL)

- Male median lobe strongly broadened subapically, its maximum width two or more times its medial width (Fig. 117J*). Apex of female elytra conjointly truncate, thus, hind margin of elytra and suture forming approximately a right angle (Fig. 117G*, 117H*); subapical tooth more or less right angled. Species known from the Rocky Mountains of western Alberta, south-eastern British Columbia and western Montana ......... ............................................................................................. O. productotruncatus (HATCH)

Figures

Figs 7-8: Oreodytes dauricus: (7) median lobe of aedeagus (a) lateral view, right side, (b) ventral view, (c) lateral view, left side; (8) paramere, external view. Figs 9-10: O. shorti: (9) median lobe of aedeagus (a) lateral view, right side, (b) ventral view, (c) lateral view, left side; (10) paramere, external view. Figs 11-12: O. dauricus: right foreleg of (11) male, (12) female. Figs 13-14: O. shorti: right foreleg of (13) male, (14) female. Fig. 15-18: O. dauricus: (15) last abdominal sternum of female; (16-17) gonocoxosternum, ventral view, two shape variants; (18) gonocoxae, ventral view.