Eucyclops productus Kiefer, 1939

Ding, Ruirui, Chen, Feizhou & Alekseev, Victor R., 2022, A redescription of the rare eucyclopine copepod Eucyclops productus Kiefer, 1939 (Multicrustacea: Copepoda: Cyclopoida: Cyclopidae) and a keу to Eucyclops subgenera and species of China and adjacent areas, Zootaxa 5182 (4), pp. 377-388 : 378-384

publication ID	https://doi.org/ 10.11646/zootaxa.5182.4.4
publication LSID	lsid:zoobank.org:pub:E701B5C9-B2E6-40EE-ADAC-B61FBD952021
DOI	https://doi.org/10.5281/zenodo.7061751
persistent identifier	https://treatment.plazi.org/id/413E87C2-C64D-FF98-FF4D-2727FB0ABCF5
treatment provided by	Plazi
scientific name	Eucyclops productus Kiefer, 1939
status

Treatment

Eucyclops productus Kiefer, 1939 ( Figs. 1–6 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 ; Table 1 View TABLE 1 )

Eucyclops productus Kiefer, 1939: 141–143 , fig 15a–e (female)

Type locality. — Chushul , India

Material examined. — Lake Mandongco. 8 females, 7 males; NIGLAS 20000101–113; 1 female and 1 male dissected and mounted on slides ( NIG 20180001–0002 View Materials ); all specimens collected by F.Z. Chen.

Redescription. Female ( Figs. 2–4 View FIGURE 2 View FIGURE 3 View FIGURE 4 ). Body length (exclusive of caudal setae) 1200–1620 µm (n=8). Except for the orange genital double somite, other parts of the body grayish brown. Cephalothorax about 1.1 times longer than width, with the greatest width close to the posterior end ( Fig. 2A View FIGURE 2 ). The length of the genital double somite slightly longer than the width, which is similar to the inverted trapezoid. Pediger V with a hair–like setae on lateral margins ( Fig. 2D View FIGURE 2 ). Anal plate slightly convex. Posterior margin of anal somite with row of spinules.

Caudal rami ( Fig. 2C View FIGURE 2 ) slender and slightly divergent, 7–8 times longer than wide. Caudal rami bearing slightly reduced serra (row of spinules along lateral margin), extending along about two thirds of ramus length and six terminal setae at the distal part of the ramus, more or less plumose. Proportions of the length of the four distal setae: 1/4.23–5.43/7–7.79/1.12–1.33 (from s1 to s4). Dorsal caudal seta shorter, and innermost seta longer than outermost seta.

Antennule ( Fig. 2B View FIGURE 2 ) 12–segmented, short, hardly reaching posterior border of cephalothorax, with a smooth/ finely serrate hyaline membrane at three last segments. Setation of A1 segments beginning from the first: 8/4/2/6/4/ 2/2/3/2/2/3/7+I (Arabic: seta, Roman numeral: aesthetasc). First segment of A1 with a row of long spinules.

A2 ( Fig. 3A, C View FIGURE 3 ) 4–segmented (composed of basipodite and 3–segmented endopodite), setation of segments beginning from basipodite: 3/1/9/7. Frontal side ornamentation of A2 basipodite ( Fig. 3B View FIGURE 3 ): a group of small spinules (groups N9) at the insertion of medial setae, a group of spinules (group N8) proximal to it, few spinules (group N7) at exopodal seta and three rows of spinules (groups N10, N11, N12) at the lateral margin. Caudal side ornamentation of A2 basipodite ( Fig. 3D View FIGURE 3 ): consists of oblique proximal and longitudinal lateral groups of spinules (groups N3, N4, N5); hair–setules (groups N1, N2) absent at distal margin.

Mandible ( Fig. 3F–G View FIGURE 3 ) short and small. Gnathobase of the mandible with 10 large blunt or pointed teeth. On the palp one small and two long setae with a row of spinules around them.

Maxilla ( Fig. 3I View FIGURE 3 ) praecoxa bearing two long strong setae and short transverse row of spinules on the opposite margin. Maxilla setation as typical for Eucyclops .

Maxillule ( Fig. 3H View FIGURE 3 ) biramous, praecoxa with seven strong spines and a short strong seta. Basal excite with seven differing length setae and a spine. Maxillulary palp smooth, not armed with spinules.

Maxilliped ( Fig. 3E View FIGURE 3 ) 4–segmented. Armament as typical for Eucyclops . Praecoxa with two strong setae in the middle part of the distal margin and a relatively small seta at the end of the same margin. Basis with a strong seta at the distal margin and a short spine at its surface with a group of short spinules at its base. The first segment of endopodite with a strong spine and a row of setules around the rudimentary rest of the last segment and the endopodite bearing a strong spine and two hairless setae.

Legs P1–P5 symmetrical. P1–P4 ( Fig. 4 View FIGURE 4 ) exo– and endopodites 3–segmented, exopodite spine formula 3/4/4/3. Distal segments of P1–P4 exopodites with five setae. Distal segments of P1–P3 endopodites with a spine and five setae.

P1 intercoxal plate ( Fig. 4A, B View FIGURE 4 ) frontally with rows of spinules on each side. Distal margin with two round projections. Coxopodite ornamented with a short row of hair–setules along lateral margin (group F). Coxal seta bearing dense hair–setae on both sides. Inner outgrowth of basipodite with long dense hair–setules. Spiniform inner seta of basipodite reaching middle of distal segment of endopodite.

P2 intercoxal plate ( Fig. 4C, D View FIGURE 4 ) frontally with rows of spinules on each side. Coxopodite ornamented with two groups of spinules and a short row of hair–setules along lateral margin (group F). Coxal seta bearing dense hair–setae on both sides. Inner outgrowth of basipodite with dense hair–setules.

P3 intercoxal plate ( Fig. 4E, F View FIGURE 4 ) frontally and caudally with rows of spinules on each side. Coxopodite ornamented with groups of spinules and a short row of hair–setules along lateral margin (group F). Coxal seta bearing long hairs proximally and short denticles distally. Inner outgrowth of basipodite with dense long hair–setules.

P4 intercoxal plate ( Fig. 4G–H View FIGURE 4 ) frontally and caudally with rows of long spinules on each side (groups II, III), distal margin with rare hair–setules (group I). Coxopodite ( Fig. 4G, J View FIGURE 4 ) ornamented with groups of spinules (groups A, B, C, D, E, H), a group of tiny spinules (group I) proximal to intercoxal plate and a short row of hair–setules along lateral margin (group F). Among them, groups C+D with a gap, group I small and dense, dot-like. Coxal seta ( Fig. 4G, J View FIGURE 4 ) bearing long hairs proximally and short denticles distally. Inner outgrowth of basipodite with sparse hair–setules ( Fig. 4G View FIGURE 4 ). P4enp3 ( Fig. 4I View FIGURE 4 ) elongated, approximately 2.5 times as long as wide, bearing two strong distal spines; the inner spine approximately 1.4 times longer than the outer one.

P5 ( Fig. 2E View FIGURE 2 ) 1–segmented, bearing of two setae and a spine. The inner spine long and strong with few fine hair–setules and small spinules at the base. The middle seta almost 2 times longer than outer one, and slightly longer than inner spine.

Egg sacs bearing about 12–13 large eggs each.

Male ( Fig. 5 View FIGURE 5 ). Body length (exclusive of caudal setae) 1060–1180 µm (n=7). The body slenderer than in female. The body color same as in female. Cephalosome 1.1 times longer than wide ( Fig. 5A View FIGURE 5 ). A1 14–segmented. Pediger V without lateral groups of setae. Caudal rami shorter than in female, without lateral serra ( Fig. 5B View FIGURE 5 ). The characteristics of mouth appendages and P1–P5 similar to females. P4enp3 approximately 2.1 times as long as wide, and the inner spine 1.55 times as long as the outer one. Coxal setae of P4 same as female, armed with long hairs in proximal part and short denticles in distal part. Distal margin of P4 intercoxal plate with fewer hair–setules ( Fig. 5E View FIGURE 5 ). P4 coxopodite ornamentation with merged groups C and D ( Fig. 5D View FIGURE 5 ).

P6 ( Fig. 5C View FIGURE 5 ) with two setae and a strong slightly longer spine, the length of spine 55–57μm, almost reaching the distal border of the next somite. The length proportions from outer seta to inner spine: 1/0.94/1.22.