Stenhelia taiae Mu & Huys, 2002

Karanovic, Tomislav, Kim, Kichoon & Lee, Wonchoel, 2014, Morphological and molecular affinities of two East Asian species of Stenhelia (Crustacea, Copepoda, Harpacticoida), ZooKeys 411, pp. 105-143 : 121-123

Stenhelia taiae Mu & Huys, 2002 Figs 7-12

Synonymy.

Stenhelia taiae sp. n. - Mu and Huys 2002, p. 187, Figs 10-13.

Type locality.

China, Bohai Sea, central region, sandy and muddy sediments at about 20 m depth, approximately 38.5°N, 120°E.

Specimens examined.

One female on one SEM stub (collection number NIBRIV0000232718), one female dissected on one slide (collection number NIBRIV0000232719), and two females destroyed for DNA sequences (GenBank accession nos. KF524885 & KF524884); all from South Korea, South Sea, Gwangyang Bay, sampling station 16, muddy sediments at about 10 m depth, 34.768889°N, 127.783806°E, 18 November 2012, leg. K. Kim.

Redescription of female.

Body length from 565 to 578 μm (n = 4). Body segmentation, colour, nauplius eye, hyaline fringes, integument thickness and surface appearence as in Stenhelia pubescens , including very smooth integument on all somites and their posterior frills. Most somite ornamentation also similar to Stenhelia pubescens , and homologous pores and sensilla easy to establish. Habitus (Fig. 8A) slightly less robust, with proportionately longer urosome (arrowed in Fig. 8A), prosome/urosome length ratio less than 1.1, body length/width ratio about 3.1, cephalothorax 1.6 times as wide as genital double-somite.

Rostrum (Figs 8H, 10D) slightly longer and narrower in dorsal view than in Stenhelia pubescens (arrowed in Fig. 10D).

Cephalothorax (Fig. 8B) about 0.9 times as long as wide; comprising about 30% of total body length, with posterior lateral corner slightly more rounded than in Stenhelia pubescens . Surface of cephalothoracic shield ornamented as in Stenhelia pubescens , except one anterior pair of lateral sensilla absent (arrowed in Fig. 8B) and one additional pair of anterior pores present (also arrowed in Fig. 8B).

Pleurons of second to fourth pedigerous somites (Fig. 8C) without any difference in shape or ornamentation from those in Stenhelia pubescens .

First urosomite (Figs 8D, 10A, B) with three pairs of long sensilla, as in Stenhelia pubescens , but with one additional short row of strong lateral spinules (arrowed in Fig. 8D).

Genital double-somite (Figs 8D, 10A, B) shape and most ornamentation as in Stenhelia pubescens , except anterior dorsal pair of sensilla more widely spaced (arrowed in Fig. 10A), posterior ventral pair of sensilla closer to each other (arrowed in Fig. 10B), and no spinules in between posterior dorsal pair of sensilla.

Third urosomite (Figs 8E, 10A, B) as in Stenhelia pubescens , except no spinules in between posterior dorsal pair of sensilla.

Fourth urosomite (Figs 8E, 10A, B) as in Stenhelia pubescens , except with fewer lateral spinules (arrowed in Fig. 8E).

Anal somite (Figs 8F, 10A, B) similar to that in Stenhelia pubescens , but additional pair of dorsal pores present, posterior spinules smaller and less dense, and medial cleft slightly narrower.

Caudal rami (Figs 8F, G, 10A, C), much longer than in Stenhelia pubescens (arrowed in Fig. 10A), about 1.3 times as long as anal somite, cylindrical, 2.1 times as long as wide (ventral view), slightly divergent, and with space between them about one ramus width; ornamentation and armature as in Stenhelia pubescens , except inner apical seta much shorter and smooth (arrowed in Fig. 10C), and ventralmost lateral seta smooth and slender; posteroventral tubular pore also present, but ventral pore at base of lateral setae situated at two thirds of ramus length, not at midlength.

Antennula (Fig. 9A), antenna (Fig. 9B), labrum (Figs 9C, 11A), paragnaths (Fig. 11B), mandibula (Fig. 9B, C), maxillula (Figs 9B, D, 11C), and maxilla (Figs 9D, 11D) as in Stenhelia pubescens .

Maxilliped (Fig. 11E) as in Stenhelia pubescens , except basal setae proportionately longer (arrowed in Fig. 11E) and apical endopodal spine proportionately shorter.

First leg (Figs 8A, C, 12A) as in Stenhelia pubescens , except first exopodal segment proportionately shorter, both basal spines proportionately longer, and coxa without posterior spinules (all four arrowed in Fig. 12A).

Second leg (Figs 8A, C, 12B) as in Stenhelia pubescens .

Third leg (Figs 8A, C, 12C) as in Stenhelia pubescens , except distomedial basal process slightly larger (arrowed in Fig. 12C).

Fourth leg (Figs 8A, 12D, E) as in Stenhelia pubescens , except distomedial basal process larger (arrowed in Fig. 12D), both inner setae on third endopodal segment with additional short pinnules (arrowed in Fig. 12E), and inner apical seta on third endopodal segment with short outer pinnules (arrowed in Fig. 12E).

Fifth leg (Figs 8D, 12F) segmentation, general shape, number of armature elements, and most ornamentation as in Stenhelia pubescens , except exopod proportionately shorter (arrowed in Fig. 8D), second endopodal seta from inner side shorter (arrowed in Fig. 12F), second and third endopodal seta from inner side shorter (both arrowed in Fig. 12F), and spaces between central endopodal seta and two neighbouring setae significantly wider (both arrowed in Fig. 12F). Distal whip on second endopodal seta much shorter than in Stenhelia pubescens , only about 0.35 times as long as proximal stout part of seta (including transverse serrate comb). Length ratio of endopodal setae, starting from inner side, 1: 0.4: 0.6: 0.5: 0.4. Length ratio of exopodal setae, starting from inner side, 1: 0.5: 0.7: 0.5: 0.5: 0.6.

Sixth leg (Fig. 10B) as in Stenhelia pubescens .

Variability.

Most morphological features in the examined Korean specimens were extremely conservative, including the sensilla and pores pattern on somites, and length ratio of different armature on appendages. Except for the body length, the only other variable feature in the Korean population was the number of spinules on the inner margin of the fifth leg exopod (compare Figs 8D and 12F). We redescribe this species in order to show some previously unreported characters, so they can be compared with those of Stenhelia pubescens . Differences from the original description of Mu and Huys (2002) are given in the Discussion section below.