Eurycercus glacialis Lilljeborg 1887

Eurycercus glacialis Lilljeborg, 1887

( Figs 1–3)

Eurycercus glacialis Lilljeborg 1887, P. 154–155; Lilljeborg 1901, P. 393–398, Pl. 60: Fig. 11, Pl. 61: Figs 1–13; Wibaut- Isebree Moens 1913, P. 227–233, Figs 2, 4; Redeke 1930, P. 87–88; Beijerinck 1931, P. 243–246, Figs 3, 4; Luyten 1933, P. 71–72, Figs 12–13; Wagler 1937, P. 50, Figs 186b, d, 187 (after Lilljeborg, 1901); Poulsen 1939, P. 22, Fig. 8 a; Poulsen 1940, P. 29–33, Fig. 11; Redeke 1948, P. 405–406, Fig. 397; Kaiser 1959. P. 17–33, Figs 5 A–B, 6A, 7B, 8–9; Frey 1958, Pl. 36: Figs 20, 24; Herbst 1962, P. 80: Fig. 54a–c; Manujlova 1964, P. 210, Fig. 98: 1–4; Frey 1971, P. 258–260 (in partim); Flössner 1972, P. 272–274, Fig. 129; Duigan & Frey 1987, P. 241–247, Figs C–D; Hann 1990, P. 2146, Figs 1–14; Duigan 1991, Figs 1–2; Minakawa & Tanaka 2000, P. 891–892; Røen 1995, P. 195–197, Fig. 90B, 91A–C (after Lilljeborg 1901 & Flössner 1972); Flössner 2000, P. 227–230, Fig. 86a–l; Minakawa et al. 2006, P. 111–114, Figs 1–10; Bekker 2012, P. 119–125, Figs 38–40; Novichkova et al. 2014, P. 1761; Novichkova & Chertoprud 2016, P. 1361.

Eurycercus lamellatus (Mueller) in Wesenberg-Lund 1894, P. 123–125, Pl. 4: Fig. 20.

Eurycercus glacialis ? Lilljeborg in Inoue 1968, P. 152, Fig. 4.

not Eurycercus glacialis in Cushman 1908, P. 710–711, Pl. 61: Fig. 5, Pl. 62: Figs 1–3.

Type locality. Unknown waterbody in Bering Island, Commandor Islands, Russia.

Type material. Lectotype and paralectotype. UUZM #547 a–m, from "Beringön 1882-1883, Fr. Steineger" (Hann 1990).

Material examined here. Greenland (Denmark): 10 parthenogenetic ♀♀ from unnamed shallow pond (<1m) (N67.148°, W50.08°) near Kangerlussuaq and glacial ice sheet margin, coll. in 0 8.2009 by Y. Axford, AAK 2010- 0 0 7. 4 parthenogenetic ♀♀ from unnamed lake with narrow rocky shelf (N67.129°, W50.17°) near Kangerlussuaq and glacial ice sheet margin, coll. in 0 8.2009 by Y. Axford, AAK 2010-008. 10 parthenogenetic ♀♀ from Tigssaluk (appr. N61.36°, W48.58°), coll. in 1880 by N.O. Holst, UUZM 38866.

Iceland: 4 parthenogenetic ♀♀ from a lake (N66.351°, W14.97°) on Langanes Peninsula (middle), coll. in 12.06.2012 by E. Chertoprud & A.A. Novichkova, AAK M-2559. 1 parthenogenetic ♀ from a lake near Drainage Divide, coll. in 18.08.1972 by D.G. Frey. 7 parthenogenetic ♀♀ from Pond 31 near Godafoss, Skjálfandafljót, Mývatn, Northeast Region, coll. in 17.08.1972 by D.G. Frey, DGF 3224-3225. 24 parthenogenetic ♀♀ from Pond 34, Seydisfjördur. coll. in 18.08.1972 by D.G. Frey, DGF 3229. 22 parthenogenetic ♀♀ from Pond 35, Seydisfjördur, coll. in 18.08.1972 by D.G. Frey, DGF 3231-3233. 2 parthenogenetic ♀♀ from Pond 37, Seydisfjördur, coll. in 18.08.1972 by D.G. Frey, DGF 3234. 1 parthenogenetic ♀ from Pond 39, Lagarfljót, coll. in 19.08.1972 by D.G. Frey, DGF 3236. 2 parthenogenetic ♀♀ from Pond 39, Lagarfljót, coll. in 19.08.1972 by D.G. Frey, DGF 3237. 120 parthenogenetic ♀♀ from Pond 45, Westside of Lake at Egilsstaðir, coll. in 19.08.1972 by D.G. Frey, DGF 3243. 50 parthenogenetic ♀♀ from Pond 47, Egilsstaðir, coll. in 19.08.1972 by D.G. Frey, DGF 3246. 50 parthenogenetic ♀♀ from Pond 47, Egilsstaðir, coll. in 19.07.1972 by D.G. Frey, AAK 2010-069. 31 parthenogenetic ♀♀ from Pond 48, Egilsstaðir, coll. in 19.07.1972 by D.G. Frey, DGF 3247. 38 parthenogenetic ♀♀ from Pond 49, Egilsstaðir, coll. in 19.07.1972 by D.G. Frey, DGF 3248. 26 parthenogenetic ♀♀ Pond 52, 2.4 km from Egilsstaðir, coll. 20.07.1972 by D.G. Frey, DGF 3251. 14 parthenogenetic ♀♀ from Pond 56 near Eidar, coll. in 20.07.1972 by D.G. Frey, DGF 3257. 40 parthenogenetic ♀♀ from Pond 57, Eidar, coll. in 20.07.1972 by D.G. Frey, DGF 3258.

Netherlands: 1 parthenogenetic ♀ from a small eutrophic water body (appr. N53.45°, E5.7°) on Ameland Island, Westfrisian Islands, coll. in 12.08.1980 by W. Hollwedel, AAK 1999-109. 10 parthenogenetic ♀♀ from Badhujsplak Dune Lake (appr. N53.4°, E5.3°), Terschelling Island, Westfrisian Islands, coll. in 24.08.1965 by P.

Leentvaar, NNS 1999 - 006. 10 parthenogenetic ♀♀ from unknown dune lake, coll. in 24.08.1965 by U. Hunenplak, NNS MGU 0 328.

Russia (Asian): 1 parthenogenetic ♀ from Lake Ladyginskoe (appr. N55.26°, E165.96°), Bering Island, Kamchatka Area, coll. in 2002 by Zh. Antipushina, AAK 2008-098. 15 parthenogenetic ♀♀ from a water body (appr. N55.3°, E165.9°) near Lake Ladyginskoe, Bering Island, Kamchatka Area, coll. in 13.08.2011 by A.A. Novichkova, AAK M-2269. About 50 parthenogenetic ♀♀ from Lake Tsentral'noje (N54.496°, E159.98°), Caldera Uzon, Kamchatka Area, coll. in 29.08.1995 by Y.R. Galimov, NMK 2712. 8 parthenogenetic ♀♀ from a lake (appr. N53.01°, E143.09°) about 15 krn northeast of Neftegorsk and 3 km northwest of Point Matny in Piltun Bay, Northern Sakhalin, Sakhalin Area, coll. in 14.08.2003 by V.V. Bogatov & N. Minakawa, AAK M-0513. 20 head shields from a shallow lake (appr. N62.06°, E156.32°), 20 km N of Merenga village, Magadan Area, NNS 1999 - 0 0 7. 5 parthenogenetic ♀♀ from a lake in tundra (appr. N59.6°, E150.9°), vicinity of Magadan, Magadan Area. coll. in 13.08.1975 by E.A. Streletskaya, NNS 1999 -009. 1 parthenogenetic ♀ from a water body in the Anadyr River basin, №348, б-135-72, Chukot Autonomous Area, coll by E.A. Streletskaya, NNS 1999 -012.

U.S.A. (Alaska): 10 parthenogenetic ♀♀ from a shallow pond (N57.829°, W152.41°) in sitka spruce temperate rainforest, Kodiak Island, coll. in 12.08.2005 by D.J. Taylor, AAK M-1115. 5 parthenogenetic ♀♀ from Moor at Talsome (?), ca. 150 km NE of Ancourage, coll. in 28.08.1978 by R. Harmsworth, DGF 6945. 25 parthenogenetic ♀♀ from a pond (N64.881°, W163.7°) near Council, Sewart Peninsula, coll. in 29.07.2011 by D.J. Taylor, A.A. Kotov, M. Ballinger & A. Medeiros, DJT20_2011_Council 0 6. 7 parthenogenetic ♀♀ from a pond (N64.874°, W163.7°) near Council, Sewart Peninsula, coll. in 29.07.2011 by D.J. Taylor, A.A. Kotov, M. Ballinger & A. Medeiros, DJT20_2011_Council 0 9. 35 parthenogenetic ♀♀ from a pond (N64.878°, W163.7°) near Council, Sewart Peninsula, coll. 0 208.2011 by D.J. Taylor, A.A. Kotov, M. Ballinger & A. Medeiros, DJT20_2011_Council 25. 19 parthenogenetic ♀♀ from a pond (N64.926°, W164.9°) near Taylor, Sewart Peninsula, coll in 30.07.2011 by D.J. Taylor, A.A. Kotov, M. Ballinger & A. Medeiros, DJT3 2011_Taylor 100.

Diagnosis. Parthenogenetic female. In lateral view body sub-ovoid (Fig. 1 A), maximum height of the body in its middle portion (BH/BL= 0.63–0.74; VL/BL=0.81–0.93). In anterior or dorsal view, body is not compressed laterally, median dorsal keel absent (Fig. 1 B–C). Rostrum relatively long (Fig. 1 D). Ocellus small. Head shield wide (Fig. 1 E). Dorsal head pores located in midline of head shield in its posterior portion; no projections in this area, ring of major head pore not elevated above head shield. Lateral head pores elongated along longitudinal body axis (Fig. 1 F). Labrum with a large median keel terminated as an angled apex projected beyond tip of antenna I (Fig. 1 D, G). Postabdomen as a large (PL/BL= 0.42–0.52), relatively broad (PH /PL= 0.51–0.61) plate with subparallel ventral and dorsal margin (Fig. 2 A) and deep anal embayment (Fig. 2 A–B). Preanal teeth pointed (NT= 99–110 in adults), dark, strongly chitinized or without pigmentation (Fig. 2 C), a gap between proximalmost tooth and bases of postabdominal setae (Fig. 2 D). Teeth in distal part of postanal margin large, long, predominantly doubled; teeth in distal part of anal – basal part of postanal margin short, almost all of them single (Fig. 2 B). Postabdominal claw relatively robust (CL/PL=0.21–0.29) with two basal spines (DS/CL=0.27–0.37; BS/CL=0.11– 0.16; BS/DS=0.31–0.48). Antenna I elongated (AL/BL=0.10–0.14; AL/DA=4.3–5.5); antennular sensory seta (Fig. 2 E, ass) arising in antenna I distal part (Fig. 2 E); numerous short rows of minute denticles encircling antennular surface. On antenna II, a spine situated on proximal segment of exopod equal in length of that of second segment or slightly longer (Fig. 2 F). Limb I with IDL (Fig. 2 G, IDL) with three bisegmented setae, one of them a relatively strong hook-like seta, its diameter at base is equal or slightly more than diameter at base of longest setae of IDL. The smallest of the three setae relatively short, its length in two or more times less than longest setae of IDL. IDL supplied with 10–12 long distal spinules (Fig. 2 H–I, dis), 11–15 long proximal spinules (Fig. 2 H, pro), and 10 very short basal spinules (Fig. 2 H, bas), marginal spinules absent (Fig. 2 H, position of these spinules in other species marked as mar). Eight setae in filter plate II (Fig. 3 A, fpl), four setae in distal armature of gnathobase II (Fig. 3 B, dag); 10 setae in filter plate III (Fig. 3 C), three setae in distal armature of gnathobase III (Fig. 3 D); 9–10 setae in filter plate IV (Fig. 3 E), four setae in distal armature of gnathobase IV (Fig. 3 F), 8–9 setae in filter plate V (Fig. 3 G), two hooks on gnathobase V (Fig. 3 H); limb VI as a oval plate (Fig. 3 I). Exopodite IV (Fig. 3 E, ext) with 8 setae, exopodite V with 8 setae. Intestine with a double loop (Fig. 1 A, ilp), posterior intestinal caecum absent (Fig. 1 A, pic).

Ephippium. Entire shell serves as ephippium, which is from almost transparent to strongly pigmented depending on environmental conditions (Kaiser 1959).

Adult male (short diagnosis based on Flössner (1972, 2000)). In lateral view body more elongated as compared with female. Rostrum short. Labral keel small (shorter than antenna I), with a well-developed apex. Postabdomen as in female. Antenna I more thick as compared with that in female, with relatively short antennular sensory setae, located at a distance of 1/3 antenna length from its distal end, and a small male setae located almost medially. Terminal aesthetascs relatively long; additional aesthetascs on posterior surface on antenna I body. Limb I supplied by a strong clasping hook located between IDL and ODL.

Size. Adult parthenogenetic females 3.32–4.32 mm (in our material); adult parthenogenetic females 4.2–6.1 mm (Hann, 1990); male 1–2 mm (Flössner, 1972).

Differential diagnosis. Among the species of Eurycercus (Teretifrons), E. glacialis is unique having no projections in the head pore area and a ring of major head pore not elevated above headshield. In contrast to E. chernovi sp.nov., it has 10 setae in exopodite IV and 8 setae in exopodite V.

Distribution. The species is apparently present in Greenland, Iceland, British Islands (Duigan & Frey 1987; Duigan 1991), northern islands of Germany and Netherlands, northern Belgium (Flössner 1972, 2000; De Meester & Bosmans 1993) in Europe; Sakhalin Island, Kurile Islands, Magadan Area, continental Kamchatka Peninsula, Bering Island, Chukotka Peninsula, continental Alaska, Kodiak Island (and, most probably, Aleutian Islands) in Pacific region. In contrast, records from European-Asian Arctic coast (i.e. Scandinavia, Kola Peninsula, Siberia, Vaigatch Island, Novaya Zemlya, and other localities, see Flössner 1972) must be checked, as well as all records from Arctic Canada and U.S.A. (see review of Frey 1971). Such populations could belong to another species (i.e.

described below or undescribed ones). Population determined as E. glacialis from Hokkaido (Inoue, 1968) could belong to another species. Frey (1971) concluded that this is in reality E. lamellatus, but most probably the latter is absent in Japan (Bekker et al. 2012). At the same time, Japanese populations could really belong to E. glacialis, because it is present in North Kurile Islands and Sakhalin (Minakawa & Tanaka 2000; Minakawa et al. 2006), the next-door territories to Hokkaido. See information on ecological preferences of this species in Flössner (1972, 2000).

Comments. At this moment, we can conclude that E. glacialis is an adequately described taxon, see history of its studies in Hann (1990).