Eurycercus lamellatus (O. F. Müller, 1776 )

Bekker, Eugeniya I., Kotov, Alexey A. & Taylor, Derek J., 2012, A revision of the subgenus Eurycercus (Eurycercus) Baird, 1843 emend. nov. (Cladocera: Eurycercidae) in the Holarctic with the description of a new species from Alaska, Zootaxa 3206 (1), pp. 1-40 : 8-10

Eurycercus lamellatus (O. F. Müller, 1776)

Lynceus lamellatus O. F. Müller, 1776, p. 199 ; O. F. Müller 1785, p. 73 –74, Pl.9, figs 4–6.

Eurycercus lamellatus (O. F. Müller) in Baird 1843, p. 88 –89, Pl. 2, figs 1–8; Baird 1850, 124–125, Pl. 15, figs 1, 1a–l; Lilljeborg 1901, p. 385 –393, Figs 59–60; Behning 1941, p. 241 –244, Fig. 102; Herbst 1962, p. 78, Fig. 53a–e; Šrámek-Hušek et al. 1962, p. 313 –314, Fig. 115; Flössner 1972, p. 268 –272, Figs 127–128; Negrea 1983, p. 232 –235, Fig. 94; Margaritora 1983, p. 101, Figs 6C , 8C , 10B , 64; Margaritora 1985, p. 203 –206, Fig. 82A, C-H (not B!); Duigan & Frey 1987, p. 241 –247, Pls A–B; Sars 1993, p. 115 –116, Fig. 85; Røen 1995, p. 193 –195, Figs 89, 90A; Alonso 1996, p. 254 –257, Figs 113–114; Silva- Briano 1998, p. 48–50, Figs 89–100; Flössner 2000, p. 224 –227, Fig. 85; Kotov 2000, p. 160 –170, Figs 1 –94; Hudec 2010, p. 266, Figs 63, 63a; Kotov et al. 2010b, p. 234 –235, Fig. 137(1–8).

Lynceus laticaudatus Fischer, 1848, p. 187 –188, Pl. 8, figs 4–7; Fischer 1850, p. 4 (= L. lamellatus ); Leydig 1860, p. 209.

Eurycercus lamallatus (Fischer) in Schödler 1862, p. 9 –10.

Eurycercus polyodontus Dybowski & Grochowski, 1898, p. 36 –37, Fig. 2 ( Dybowski & Grochowski 1894, p. 380 —Nomen nudum; Dybowski & Grochowski 1895, p. 149 —Nomen nudum).

Type locality. No information on the exact locality is present in the first description (O. F. Müller 1776) and in the author’s redescription (O. F. Müller 1785). But it is known that most of Müller's taxa were described from “Frederiksdal, located slightly north-west of Copenhagen between Fuersø and Bagsvaeds Sø” ( Frey 1980), Denmark.

Type material. Apparently lost ( Frey 1980).

Material examined here. Many parthenogenetic, ephippial females and males from Denmark, Iceland, Fin- land, Norway, France, Germany, The Netherlands, Czech Republic, Lithuania, Belarus, Ukraine, different Areas of European and Asian Russia, Kirghizia, Tajikistan and Mongolia ( Fig. 1 ). A full list will be represented in a special future publication concerning a revision of the lamellatus -like forms worldwide.

Diagnosis. Parthenogenetic female. Dorsal head pores on a transverse fold in posterior portion of head shield with an indentation behind it. In anterior view, body moderately compressed laterally, median keel passes through whole carapace dorsum and actually begins on the head behind head pores. Rostrum long. Ocellus minute. Lateral head pore elongated along longitudinal body axis. Labrum with a large median keel, terminating in an angled apex protruding beyond distal end of antenna I. Postabdomen with sub-parallel dorsal and ventral margins, preanal teeth pointed. Spines at base of pre-claw portion predominantly single. Antenna I with antennular sensory seta arising in middle. Denticles in rows encircling antennular surface relatively large and numerous. On antenna II, spine situated on proximal segment of exopod equal or longer than second segment. Limb I IDL with a hook-like seta only somewhat thicker than longest seta, smallest seta not very short. IDL with distal, proximal, marginal (which is relatively reduced) and basal group spinules. Eight setae in filter plate II, 9 setae in filter plate III; 9 setae in filter plate IV, 8 setae in filter plate V.

Most recent redescriptions. See Alonso (1996), Kotov (2000), Hudec (2010).

Comments. In the synonymy we try to represent only recent and relatively recent publications, where the determination of E. lamellatus was really adequate (i.e. when head pore region was accurately illustrated). Unfortunately, descriptions and illustrations in many previous publications were lacking important traits. Keeping in mind the possibility to find E. pompholidodes and E. macracanthus in Europe, we need to be critical of determinations of E. lamellatus in such papers, even when the authors are well-known cladocerologists (i.e. Schödler 1862; Müeller P.E. 1867; Hellich 1877; Matile 1890; Wesenberg-Lund 1894). Some authors redrew pictures by Lilljeborg (1901) to illustrate specimens from geographically distant populations. Taxonomic assignment of such redrawn specimens is uncertain. See extensive comments in Smirnov (1971) and Frey (1971).

Distribution. E. lamellatus is widely distributed in the Palaearctic from Spain in the West up to the Anadyr basin ( Streletskaya 2010) in the East. Records from Chukot Peninsula, Kamchatka Peninsula and Alaska ( Tash & Armitage 1967; Kurenkov 2005) could belong to some other species described below. At least, we did not see this species in our material from Beringia East of the Kolyma River. The southern border is not well-known, populations from India and Tibet ( Frey, 1971) could belong to a congeneric species.

Margaritora (1985, Fig. 82B) represented a drawing of a male of “ E. lamellatus ” with a bubble-like projection in region of head pores, but it could be inadequate drawing. At present, it seems that only E. lamellatus occurs in Central and South Europe.

Ecology. See detailed analysis by Flössner (2000).

Figures

FIGURE 1. Distribution of species from the subgenus Eurycercus (Eurycercus) emend. nov. in the Holarctic according to our original samples—no literature data included. E. lamellatus—grey circles. E. macracanthus—black circles. E. pompholygodes—solid quadrates (red in electronic version). E. microdontus—black stars. E. longirostris—grey quadrates. E. nipponica—solid triangles (green in electronic version). E. beringi sp. nov.—black crosses.

FIGURE 2. Characteristic traits of different species of Eurycercus (Eurycercus) emend. nov. A–B, E. longirostris, dorsal view and dorsal head pores in lateral view. C–D, E. lamellatus, dorsal view and dorsal head pores in lateral view. E–F, E. beringi sp. nov., dorsal view and dorsal head pores in lateral view. Rather schematic, not to scale.

FIGURE 6. Eurycercus longirostris, parthenogenetic female from CPR WDS, California, U.S.A. (A, C, D, F, G, H, K, L); Oliver Lake, Indiana, U.S.A. (B, E, I); Lake La Luna, in the crater of the volcano Nevado de Toluca, State of Mexico, Mexico (J). A, lateral view. B, head. C, head shield. D, head pores. E, labrum, ventral view. F, setae at anterior portion of valves. G, setae at postero-ventral portion of valve. H, armature of valve posterior margin. I, postabdomen. J, its distal portion. K, antenna I. L, antenna II. Scale bar denotes 1 mm (A); 0.1 mm (B-I).

FIGURE 8. Eurycercus nipponica, female from a swampy area (with a fresh bear trail in time of sampling) near Travianoy Cape, Kurilskoe Lake, Kamchatka Area, Russia A, parthenogenetic female, lateral view. B–C, ephippial female, lateral and anterior view. D, parthenogenetic female, ventral view. E, head. F, dorsal head pores. G, postabdomen. H, its distal portion. I, its basal portion. J, antenna I. K, antenna II. Scale bar denotes 1 mm (A–D); 0.1 mm (E–K).

FIGURE 10. Eurycercus beringi sp.nov., parthenogenetic female from Council #05: a roadside pond <1.5 m deep, 10 X 25 m, Seward Peninsula, Alaska, U.S.A. A, lateral view. B, dorsal view. C, head. D–E, head pores, lateral and dorsal view. F–G, labrum, lateral and ventral view. H, valve. I, setae at antero-ventral valve portion. J, setae at postero-ventral valve portion. K, armature of valve posterior margin. L, mandible. M, postabdomen. N, its distal portion. O, its basal portion. Scale bar denotes 1 mm (A–C, H, L–M); 0.1 mm (D–G, I–K, N–O).