Eucyclops productus Kiefer 1939
Creators: name: Ding, Ruirui
name: Chen, Feizhou
name: Alekseev, Victor R.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Hexanauplia
Cyclopoida
Cyclopidae
Eucyclops
Eucyclops productus

description: Eucyclops productus Kiefer, 1939 (Figs. 1–6; 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); all specimens collected by F.Z. Chen.
Redescription. Female (Figs. 2–4). 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). 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). Anal plate slightly convex. Posterior margin of anal somite with row of spinules.
Caudal rami (Fig. 2C) 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) 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) 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): 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): 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) 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) 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) 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) 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) 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) 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) 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) 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) 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) 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) bearing long hairs proximally and short denticles distally. Inner outgrowth of basipodite with sparse hair–setules (Fig. 4G). P4enp3 (Fig. 4I) 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) 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). 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). A1 14–segmented. Pediger V without lateral groups of setae. Caudal rami shorter than in female, without lateral serra (Fig. 5B). 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). P4 coxopodite ornamentation with merged groups C and D (Fig. 5D).
P6 (Fig. 5C) 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.
description: Published as part of 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, pp. 377-388 in Zootaxa 5182 (4) on pages 378-384, DOI: 10.11646/zootaxa.5182.4.4, http://zenodo.org/record/7056560