Cyclops divergens Lindberg, 1936

Connolly, Joseph K., Marshall, Christopher C., Hudson, Patrick L., Watkins, James M., Scofield, Anne E. & Rudstam, Lars G., 2022, Reevaluation of the genus Cyclops Müller, 1776 (Cyclopoida: Cyclopidae) in the Laurentian Great Lakes basin: first report of the Palearctic species Cyclops divergens Lindberg, 1936 from Lake Erie and documentation of Cyclops sibiricus Lindberg, 1949 in the St. Marys River, Zootaxa 5182 (2), pp. 183-195 : 187-190

publication ID	https://doi.org/ 10.11646/zootaxa.5182.2.5
publication LSID	lsid:zoobank.org:pub:50BD0F07-F445-4AFE-BA85-2546FDAE52B6
DOI	https://doi.org/10.5281/zenodo.7053943
persistent identifier	https://treatment.plazi.org/id/7752315E-FFD8-8C62-FF09-F995FA7EFC74
treatment provided by	Plazi
scientific name	Cyclops divergens Lindberg, 1936
status

Treatment

Synonymy:

Cyclops strenuus divergens Lindberg (1936) : 3 −5, figs. 3−7.

Cyclops rubens divulsus Lindberg (1956) : 112 −113.

Cyclops singularis Einsle (1996b) : 170, 172−176, figs. 2−6.

Material examined: 1 female dissected and slide mounted, collected from U.S. EPA GLNPO monitoring station ER58, Lake Erie , Ohio, USA (41.67853 N, - 82.93182 W) on April 1, 2013 (planktonic abundance of <1 individual/ m³), initially reported as C. strenuus in Barbiero et al. (2019) GoogleMaps . 1 male dissected and slide mounted, collected from Maumee Bay , Lake Erie, Ohio, USA (41.70217 N, - 83.35375 W) on April 17, 2014, initially reported as C. strenuus in Hudson & Lesko (2003) GoogleMaps . 1 male dissected and slide mounted, collected from U.S. EPA GLNPO monitoring station ER61, Lake Erie , Ontario, Canada (41.94755 N, - 83.04310 W) on April 20, 2019 (planktonic abundance of <1 individual/m³). GoogleMaps 1 CV copepodite collected from U.S. EPA GLNPO monitoring station C05, Lake Erie, Ohio, USA (41.62500 N, - 82.92167 W) on July 16, 2019 (meiobenthic abundance of 19 individuals/m²) GoogleMaps .

Female: Body larger than C. sibiricus ( Table 1 View TABLE 1 ), robust and cyclopiform. Prosome longer than urosome ( Table 1 View TABLE 1 ) and cephalothorax longer then wide. Rostrum small and fairly discrete. A1 consisting of 17 segments ( Fig. 3a View FIGURE 3 ) and extending beyond the cephalothorax. A1 first segment strongly pitted ( Fig. 3b View FIGURE 3 ) as described in Krajíček et al. (2016) and ornamented with a small convex row of spinules. Setation present on A1 segments 1−9, 11−12, 14−17. Aesthetascs present on A1 segments 12, 16, and 17. Aesthetasc on A1 segment 12 extending to the midpoint of segment 14 ( Fig. 3c View FIGURE 3 ). A1 segments 15−17 with finely textured hyaline membrane ( Fig. 3d View FIGURE 3 ). A2 4-segmented with 3 setae on the basipodite including exopodite seta and 1, 9, 7 setae on the successive (endopodal) segments. A2 exopodite seta reaching beyond the distal margin of the endopodite and strongly ornamented with large spinules. Caudal surface of A2 basipodite ( Fig. 4a View FIGURE 4 ) ornamented with 6 large spinules of similar height from the lateral to distal margin, an oblique row of 5 stout spinules and a small convex row of 4 short broad based spinules at position B ( Hołyńska et al. 2003), a longitudinal row of approximately 9 spinules at position A, and flanked by a small field of approximately 12 tiny spinules at position C. In general, ornamentation of this appendage more robust in appearance then that of C. sibiricus . La with hair on caudal surface restricted to small parallel patches. Md not observed in detail. Mxl palp proximalmost seta ornamented with plumose setules in the proximal third and all 3 setae of the lateral lobe ornamented with only tiny spinules distally. Two large conspicuous spinules present on the surface of one maxillular palp and inconspicuous on the other palp. Mx not observed in detail. Mxp syncoxopodite armed with 3 plumose setae, basipodite with 2 plumose setae, endopodite 1 with 1 plumose seta, endopodite 2 with 1 plumose and 2 bare setae. Mxp sycoxopodite with relatively short membranous element with prominent hook at distal terminus ( Fig. 4b View FIGURE 4 ) as in Hołyńska & Dahms (2004) and ornamented with a transverse row of small spinules on the distal third as described in Krajíček et al. (2016). Ornamentation present on the frontal surface of successive mxp segments in the form of thin hair-like spinules except endopodite 2.

Spine formula of P1−P4 identical to C. sibiricus ( Table 2 View TABLE 2 ). Ornamentation of swimming legs as follows. P1 coupler and coxopodite unornamented. P1 coxopodite setae strongly ornamented with long setules. P1 medial margin of basipodite haired, basipodite frontal surface with a row of long spinules between the insertion of exopodite and endopodite ( Fig. 4c View FIGURE 4 ). Medial spine of basipodite setulation heteronomous with long setules proximally and abruptly decreasing in length distally ( Fig. 4c View FIGURE 4 ). P2 and P3 ornamented likewise as follows. Coupler unornamented. Coxopodite ornamented with spinules at position B and hairs at F ( Einsle 1996a). Coxopodite setae strongly ornamented with long setules. P4 coupler caudal surface ornamented with a proximally placed horizontal row of long hairs. P4 coxopodite ornamented ( Fig. 4d View FIGURE 4 ) with spinules at positions A, C, D, and E. P4 coxopodite setae long extending beyond the distal terminus of the basipodite medial margin ( Fig. 4e View FIGURE 4 ; Table 1 View TABLE 1 ) and medial margin of basipodite unhaired. P4 coxopodite setae with proximal third sparsely armed with long setules and distal 2 thirds densely armed with long setules. P4 endopodite 3 longer than wide and outer terminal spine relatively long ( Table 1 View TABLE 1 ). P5 basal segment lacking ornamentation, P5 distal segment as in C. sibiricus . P5 apical seta long ( Table 1 View TABLE 1 ) and ornamented with plumose setules distally. Genital double-somite wider then long at widest point ( Table 1 View TABLE 1 ) and surface strongly pitted. Posterior margins of proceeding 2 urosomites crenulate. Posterior margin of anal somite ornamented with fine spinules. Anal operculum unornamented. Caudal rami more than five times longer than wide ( Table 1 View TABLE 1 ) with inner margins haired. Tiny spinules present at the insertions of lateral caudal seta and S4 ( Hołyńska et al. 2003). S2 shorter than urosome and longer than caudal rami ( Table 1 View TABLE 1 ).

Males: Body as in female, with total body length shorter than female ( Table 1 View TABLE 1 ). Prosome longer than urosome, slightly more so than female ( Table 1 View TABLE 1 ) and cephalothorax longer than wide. A1 geniculate ( Fig. 5a View FIGURE 5 ), consisting of 17 segments variously modified in length and width in comparison to female. A1 first and second segment strongly pitted, pitting rapidly declines in subsequent segments. Setation present on all segments. A1 first segment with 3 aesthetascs, 2 placed proximally and 1 distally. Singular aesthetascs present on A1 segments 4, 9, 13, 16, and 17. A single pectenate seta present on A1 segments 11 and 12. A2 armature as in female. A2 caudal surface ornamentation as in female with additional spinulation at position C (approximately 20 spinules). La as in female. Md gnathobase armed with 10−12 jagged, and more or less triangular teeth of similar length but variable width and 2 setae, 1 pectenate and one bare. Md palp with 2 long plumose setae and 1 short bare seta. Mxl palp proximalmost seta ornamented with plumose setules in the proximal third ( Fig. 5b View FIGURE 5 ) and tiny spinules in the distal two thirds. Setae of the mxl palp lateral lobe lacking setules, ornamented only with tiny spinules. Large spinules present on the surface of mxl palp ( Fig. 5b View FIGURE 5 ), 3 spinules apparent on both palps in 2014 specimen, 4 spinules apparent on one palp and 3 on the other in 2019 specimen. Mx not observed in detail. Mxp armed and ornamented as in female.

P1−P4 armature as in female ( Table 2 View TABLE 2 ), P1−P4 ornamentation as in female with the exception of the P4 basipodite medial margin being partly to fully haired and long hairs on caudal surface of P4 coupler notably more abundant ( Fig. 5c View FIGURE 5 ). P4 endopodite 3 more elongate than in female ( Table 1 View TABLE 1 ). P5 as in female. Rudimentary leg 6 (P6) consisting of 3 setae, 1 long plumose seta, 1 short plumose seta, and 1 short pectenate seta, with tiny spinules present at the insertion of each seta. Urosome 5-segmented and sparsely pitted. Ornamentation of posterior margin of urosomites, anal somite, and anal operculum as in female. Morphometry of caudal rami and caudal setae similar to that of female ( Table 1 View TABLE 1 ).

Genetic Sequencing

The C. divergens CV copepodite specimen (Sample ID: ZOOPS _0581) collected from Lake Erie produced a successful COI-5P genetic sequence (http://www.boldsystems.org/index.php/Public_RecordView?processid=ZOO PS581-20). The specimen was assigned to BIN BOLD: ACL 6037 (dx.doi.org/10.5883/ BOLD: ACL 6037) which is populated with 20 COI-5P sequences of Cyclops specimens from continental Europe in the Barcode of Life Data system ( Ratnasingham & Hebert 2007). The Lake Erie C. divergens COI-5P sequence was 99.4% similar to a specimen (COPCLAD456) collected from Norway (Falkenhaug & Hobaek unpublished), 99.2% similar to a specimen ( MK 329340 View Materials ) collected from Poland ( Hołyńska & Wyngaard 2019), and 97.7−98.0% similar to three specimens ( KP 772955 View Materials , KP772957 View Materials , KP 772958 View Materials ) collected from Czechia (Krajíček et al. 2016). Mean distance between the Lake Erie C.divergens CV copepodite specimen and the above mentioned publicly available C. divergens COI-5P sequences from Europe was 1.60%. The sequenced specimen is e-vouchered in the BOLD collection at the University of Guelph, all other Lake Erie and St. Marys River Cyclops specimens are archived at the Cornell Biological Field Station.