Cyclops, O. F. Muller, 1776

Hołyńska, Maria & Dimante-Deimantovica, Inta, 2016, Redescription and taxonomic notes on Cyclops bohater Koźmiński, 1933 and Cyclops lacustris G. O. Sars, 1863 (Arthropoda, Crustacea), with an identification key to the Cyclops species of Fenno-Scandinavia, European Journal of Taxonomy 212, pp. 1-31 : 23-24

Identification key to the Cyclops species of Fenno-Scandinavia:

Character states are diagnostic both in the adult female and male (♀, Ƌ), or in the adult female (♀) only.

1. P1: spinules absent or tiny on frontal surface of basipodite near distal margin between insertions of exo- and endopodite (♀, Ƌ) ……………………………………………………………………2

̅ P1: arc (or group) of large spinules present on frontal surface of basipodite near distal margin between insertions of exo- and endopodite (♀, Ƌ) ( Fig. 3C , arrowed) ……………………………5

2. Pediger 4 with wing-like posterolateral protrusions, that is pediger 4 wider than pediger 3 (width measured as distance between posterolateral angles of the somite) (♀). Intercoxal sclerites of P1̅ P3 (and usually also P4) naked on caudal surface (♀). Mandibular coxopodite with group of large spinules near palp on frontal surface (♀, Ƌ) (site is arrowed in Fig. 2D ) ……………………………3

̅ Pediger 4 without wing-like posterolateral protrusions, that is pediger 4 narrower than pediger 3 (width measured as distance between posterolateral angles of the somite) (♀). Intercoxal sclerite of P3 (sometimes also P2) with hairs on caudal surface, P4 intercoxal sclerite caudally naked or pilose (♀). Mandibular coxopodite without spinules near palp ( Fig. 2D ) (♀, Ƌ) …………………………4

3. Antennal coxobasis: spinules small or sometimes absent on frontal surface at mediodistal angle of segment (site is shown by arrow in Fig. 2A ) (♀, Ƌ); inner medial seta with long setules (for a similar setulation pattern see Fig.7E ̅F) (♀, Ƌ). Frontal surface of maxilliped syncoxopodite with a distal (midway between insertions of median and distal seta) and proximal (midway between insertions of median and proximal seta) group of long spinules, and smaller spinules arranged in nearly ellipse line laterally to proximal group of long spinules; scattered tiny spinules sometimes also present near lateral margin (♀, Ƌ) ( Fig. 9C ) ……………… C. vicinus Uljanin, 1875

̅ Antennal coxobasis: spinules large on frontal surface at mediodistal angle of segment (♀, Ƌ); setules absent or short on inner medial seta (♀, Ƌ). Frontal surface of maxilliped syncoxopodite with two groups of long spinules only: distal group (midway between insertions of median and distal seta) and proximal group (midway between insertions of median and proximal seta) (♀, Ƌ) …………………………………………………………………………… C kikuchii Smirnov, 1932

4. Antennule usually 17-segmented (18, 17, 16, and 14-segment states were found in C. furcifer caspicus Lindberg, 1942 from a saline marsh in Golestan Prov., Iran) (♀). Anterolateral (II) caudal seta inserted at distance of 0.18̅0.23 ramus length measured from posterior end (♀). Maxillulary palp: long setules present almost at full length of proximal seta and one (proximalmost) seta of lateral lobe (♀, Ƌ). P4 coxal seta slender: seta thickness and setulation similar to those in corresponding setae of P1̅P3 (♀) ……………………………………………………………… C. furcifer Claus, 1857

̅ Antennule 14-segmented (♀). Anterolateral (II) caudal seta inserted at distance of 0.24̅0.29 ramus length measured from posterior end (♀). Maxillulary palp: proximal seta and lobe setae without long setules (♀, Ƌ). P4 coxal seta usually swollen at its base (seta thicker than corresponding setae in P1̅P3), and setules of seta short and robust (♀) ……………………… C. insignis Claus, 1857

5. Maxillulary palp: proximal seta bearing long setules (♀, Ƌ) (shown by arrow at bottom in Fig. 2E ) …6 ̅ Maxillulary palp: proximal seta without long setules (♀, Ƌ) ………………………………………10

6. Maxillulary palp: at least one of the lateral lobe setae also bearing long setules (♀) ( Fig. 2E ) ……7 ̅ Maxillulary palp: lateral lobe setae lacking long setules (♀) ………………………………………9

7. Antennal coxobasis: inner medial seta with long setules (♀, Ƌ) ( Fig. 7E ̅F). Dorsal (VII) caudal seta 1.2̅2.1 times as long as posterolateral (III) caudal seta (♀) ……… C. lacustris G.O. Sars, 1863

̅ Antennal coxobasis: inner medial seta naked or bearing short setules (♀ -Ƌ). Dorsal (VII) caudal seta shorter or just slightly longer (max. 1.2×) than posterolateral (III) caudal seta (♀) ………………8

8. P1 basipodite: medial spine proximally bearing long setules/spinules (♀, Ƌ) ( Fig. 3C , arrowed). Terminal accessory (VI) caudal seta longer than caudal ramus (♀). Dorsal caudal seta as long or slightly longer than posterolateral (III) caudal seta (♀). Caudal surface ornamentation of P4 coxopodite: group “E” present ( Fig. 3D ) (♀) ………… C. bohater Koźmiński, 1933

¯ P1 basipodite: medial spine with tiny spinules only (♀, Ƌ). Terminal accessory (VI) caudal seta shorter than caudal ramus (♀). Dorsal caudal seta usually shorter than posterolateral (III) caudal seta (♀). Caudal surface ornamentation of P4 coxopodite: group “E” absent or present (cf. Fig. 3D ) (♀) …………………………………………………………………………… C. heberti Einsle, 1996 (Occurrence of the species is expected in Fenno-Scandinavia.)

9. Maxillulary palp with tranverse row or large spinules near base of palp and field of tiny spinules more apically (♀, Ƌ) ……………………………………………………… C. divergen s Lindberg, 1936 (Synonyms: C. abyssorum divulsus Lindberg, 1956 and C. singularis Einsle, 1996 )

̅ Maxillulary palp naked or if spinules present they are tiny and scattered (♀, Ƌ) ……………… ……………………………………………………………………… C. abyssorum G.O. Sars, 1863

10. Pediger 4 with wing-like posterolateral protrusions, that is pediger 4 wider than pediger 3 (width measured as distance between posterolateral angles of the somite) (♀). Anterolateral (II) caudal seta inserted at distance of> 1/3 ramus length, measured from posterior end (♀). P5, proximal (first) segment: spinules absent at insertion of lateral seta (♀, Ƌ). Male antennule: first segment with single (distal) aesthetasc ……………………………………… C. scutifer G.O. Sars, 1863

̅ Pediger 4 with or without wing-like posterolateral protrusions, that is pediger 4 wider or narrower than pediger 3 (width measured as distance between posterolateral angles of the somite) (♀). Anterolateral (II) caudal seta inserted at distance of <1/3 ramus length, measured from posterior end (♀). P5, proximal (first) segment: spinules usually present at insertion of lateral seta (♀, Ƌ). Male antennule: first segment with three aesthetascs ………………………………………………11

11. Spine formula on terminal exopodal segments of P1̅P4, 2-3-3-3 (♀) … C. kolensis Lilljeborg, 1901 ̅ Spine formula on terminal exopodal segments of P1̅P4, 3-4-3-3 (♀) ……………………………12

12. P4 coxopodite seta reaching distinctly beyond distalmost point of medial expansion of P4 basipodite (♀, Ƌ). Intercoxal sclerites of P1̅P3 naked, P4 intercoxal sclerite caudally pilose (♀). P5, distal (second) segment: apical seta long, 2.7-4.2 times as long as segment (♀). Caudal surface ornamentation of P4 coxopodite: groups “B”and “E” usually absent (for coding of the spinule groups see Fig. 3D ) (♀, Ƌ) …………………………… C. strenuus Fischer, 1851

̅ P4 coxopodite seta not reaching beyond distalmost point of medial expansion of P4 basipodite (♀, Ƌ). Intercoxal sclerites of P3̅P4 (sometimes also P2) with hairs on caudal surface (♀). P5, distal (second) segment: apical seta short, 1.6̅2.3 times as long as segment (♀). Caudal surface ornamentation of P4 coxopodite: groups “B” and “E” present (for coding of the spinule groups see Fig. 3D ) (♀, Ƌ) ………………………………………………………… C. sibiricus Lindberg, 1949 (This species has often been confounded with C. strenuus . Cyclops sibiricus is distributed in Siberia and arctic North America; its westernmost occurrence is so far known from the Yamal Peninsula ( Lindberg 1957); occurrence in arctic Fenno-Scandinavia is possible.)

Figures

Fig. 3. Cyclops bohater Koźmiński, 1933, ♀. A. Maxilla, caudal. B. Maxilliped, frontal. C. Leg 1, frontal, arrows point to the long setules of the medial spine/seta of basipodite, and long spinules on the basipodite between the insertions of exopodite and endopodite. D−E. Leg 4: EXP, P4 exp 3; ENP, P4 enp3. All drawings show the lectotype (NHMUK 2016. 38). Scale bars: A̅E = 100 µm.

Fig. 2. Cyclops bohater Koźmiński, 1933, ♀. A−B. Surface ornamentation of antennal coxobasis. A. Frontal, arrow points to insertion site of long spinules missing in C. bohater. B. Caudal, arrow points to a group of spinules sometimes present. C. Labrum, epistoma and rostrum. D. Mandible, frontal, arrow points to insertion site of spinules missing in C. bohater. E. Maxillulary palp, arrows point to long setules of the setae, and spinulose ornamentation of the palp. All drawings show the lectotype (NHMUK 2016.38). Scale bars: A̅E = 100 µm.

Fig. 7. Cyclops lacustris G.O. Sars, 1863, ♀. A. Habitus, dorsal (SMNK: 9567). B−C. Urosome, ventral (Lake Aspern, Norway ̅ MIZ 2/2016/20). B. Urosomites 1̅4. C. Anal somite and caudal rami. D. Antennular segments 12̅17, ventral (Lake Aspern, Norway ̅ MIZ 2/2016/20). E−F. Antennal coxobasis, caudal. E. ♀ from Lake Mjøsa, Norway (ZMO: Sars Coll. 12977 ♀-2). F. ♀ from Lake Aspern, Norway (MIZ 2/2016/20). G−H. Maxillulary palp. G. ♀ from Lake Mjøsa, Norway (ZMO: Sars Coll. 12977 ♀-2). H. ♀ from Lake Aspern, Norway (MIZ 2/2016/20). Scale bars: A̅H = 100 µm.

Fig. 9. A−B. Cyclops lacustris G.O. Sars, 1863, Ƌ (ZMO: Sars Coll. 12976 Ƌ-1). A. Leg 1, frontal. B. Leg 4, caudal. C. Cyclops vicinus Uljanin, 1875, maxilliped syncoxopodite, frontal (Lake Østensjøvann, Norway ̅ MIZ 2/2016/30). Scale bars = 50 µm.