Halectinosoma kliei, Clément, Michel & Moore, Colin G., 2007

Clément, Michel & Moore, Colin G., 2007, Towards a revision of the genus Halectinosoma (Copepoda, Harpacticoida, Ectinosomatidae): new species from the North Atlantic and Arctic regions, Zoological Journal of the Linnean Society 149 (3), pp. 453-475 : 469-475

HALECTINOSOMA KLIEI SP. NOV.

Ectinosoma finmarchicum Willey, 1920: 26 , fig. 33

Ectinosoma finmarchicum Smirnov, 1932: 200 , fig. 2

Ectinosoma finmarchicum Chislenko, 1977: 238–239 , pl. 1 figs 3–5

Type material: 1♀ holotype from the Klie collection, Zoology Museum, Kiel, dissected on two slides ( COP1841 ) from Danemark Sarafse, collected by Jespersen on 13.viii.1932 ; 1♀ paratype from the Klie collection, Zoology Museum, Kiel, dissected on two slides ( COP269 ) (labelled Ectinosoma finmarchicum ), from the Dana Expedition, station 4677, 60°47′N, 42°34′W on 13.viii.1933 ; 1♂ paratype from the Canadian Museum of Nature , Ottawa, dissected on two slides ( NMCC1990-0356 ), collected by E. H. Grainger from station 75-566 in the Beaufort Sea, 78°06′N, 138°56′W, using a plankton net from 0 to 220 m, 18.vii.1975 .

Other material examined: Arctic: 1♀ on slide NMC1990-0358 ( Canadian Museum of Nature , Ottawa ), identified as E. finmarchicum by Willey , from the Canadian Arctic Expedition , 1913–18, Collinson Point, Beaufort Sea, station 27, 69°59′N, 144°50′W, collected from 2 m depth with plankton net by F. Johansen, 4.x.1913 ; 1♀ copepodite V on slide NMC1990-0357 ( Canadian Museum of Nature , Ottawa), Beaufort Sea, 78°06′N, 138°56′W, collected with plankton net from 0 to 220 m by E. H. Grainger, station 75-566, 18.vii.1975 ; 1♀ dissected on slide NMC1990-0359 ( Canadian Museum of Nature , Ottawa ), from Frobisher Bay, Baffin Island, 63°25′N, 68°10′W, collected from seabed by E. H. Grainger, 50 m, 7.vii.1975 .

Description of female holotype

Length: Habitus 800 µm; sum of all somites 935 µm; cephalothorax 255 µm; genital double-somite 130 µm. Habitus fusiform ( Fig. 11A ). Colour of preserved specimen yellowish brown. Surface of cuticle densely covered with small pores. Cephalothorax gradually attenuating anteriorly. Rostrum broadly rounded and partially fused at base with cephalothorax, with two small sensilla subapically. Genital double-somite with short transverse chitinous stripe ventrally ( Fig. 11B ). Penultimate somite with rounded pseudoperculum ( Fig. 11C ).

Caudal ramus ( Fig. 11B, C ). About as long as broadest width. Principal setation and general form as in H. pseudosarsi Clément and Moore.

Somitic ornamentation ( Fig. 11A–C ). Body somites, excluding penultimate, sparsely furnished with sensilla and pores. Posterior margin of cephalothorax, first and second free thoracic somites unadorned. Posterior margin of third thoracic somite and first urosomite finely crenulated. Genital double-somite with a complex arrangement of rows of fine spinules and a semiincised subulate hyaline frill. Urosomite 4 with hyaline frill similar to preceeding somite and with three rows of fine spinules. Penultimate somite with one dorsal and two ventral spinular rows and a very fine, fully incised, subulate hyaline frill which is interrupted dorsally by the unadorned pseudoperculum.

Antennule ( Fig. 12A ). Elongate and six-segmented. Principal setation (not illustrated) and form as in H. pseudosarsi except for small differences in the relative length and spinulation of some setae.

Antenna ( Fig. 12B ). Coxa short. Basis with a set of long setules at inner distal corner. Endopodite twosegmented; segment 1 unadorned, segment 2 with two adjacent setae mid-way along inner margin and seven terminal setae (including three spinulose, geniculate and one dwarfed, plumose). Exopodite threesegmented; basal segment well developed and armed with a slender seta, segment 2 short, with a spinulose seta, distal segment twice as long as basal one and armed with two apical setae which are spinulose and subequal in length.

Mandible ( Fig. 12C ). Only the coxal gnathobase, furnished with a short spiniform seta at ventral base of bidentate pars incisiva and tridentate lacinia, could be observed.

Maxillula ( Fig. 12D ). Only the praecoxal arthrite, armed along distal edge with three unguiform spines, could be observed.

Maxilla ( Fig. 12E ). Syncoxa short and broad, with three rows of fine spinules and furnished with three endites along distal half of inner margin; proximal endite armed with four setae, middle and distal endites with two and three setae, respectively. Basis narrower than syncoxa and nearly twice as long as broad and furnished with three setae midway along inner margin, and two slender setae near apex. Endopodite three-segmented, the first two segments each armed with a thick and very long geniculate seta and the distal segment represented by a broad base from which one lateral and three distal confluent setae arise.

Maxilliped ( Fig. 12F ). Syncoxa short with two setae. Basis segment long and with short spinules along inner and slender hairs along outer margin. Endopodite segment short, armed with two lateral and two closely set apical setae.

P1–P4 ( Fig. 13A–D ). Principal setation and form of P1–P4 as in H. mandibularis sp. nov., except setae slender and also much longer relative to the length of each leg. Coxa of P2–P4 with a row of spinules along outer distal edge and a row of very fine spinules near inner distal corner.

P5 ( Fig. 11D ). Exopod longer than broad and separated from baseoendopod by a suture on posterior surface only. Inner expansion of baseoendopod reaching to distal edge of exopod, with spinules along inner margin and furnished distally with two setae, the outer seta reaching beyond innermost seta of exopod. Outer expansion of baseoendopod furnished with a long slender seta. Exopod with a few spinules along inner margin, and with three somewhat sinuous lobes at distal edge, each accompanied by a row of spinules and armed with a slender spinulose seta: innermost seta about as long as outer seta; middle seta about as long as inner seta of baseoendopod. Surface-seta reaching beyond exopod, articulating on a small lobe accompanied by a few spinules and issuing from a point just distal to the exopod–baseoendopod suture.

Description of male paratype

Length: Habitus 770 µm; sum of all somites 750 µm; cephalothorax 220 µm. Urosomites 2 and 3 distinct. Otherwise as in female apart from the following features.

Antennule ( Fig. 12G ). Seven-segmented. Principal segmentation and setation (setae not illustrated) as in male of H. neglectum ( Sars, 1904) except posterior margin of segment 5 with a broader and longer aesthetasc and with only one grasping process which is accompanied by a short spinulose seta.

P5 ( Fig. 11E ). Baseoendopod confluent with first urosomite: inner expansion armed with two distal setae; outer expansion armed with a slender seta. Exopod clearly demarcated from baseoendopod and armed with three distal setae. Surface-seta issuing from a small lobe on exopod.

P6 ( Fig. 11F ). A plate with two subequal setae at outer distal corner. Distal edge of plate denticulate.

Variability: No differences were found among specimens examined.

Etymology: Halectinosoma kliei is named in honour of Dr Walter Klie, whose collection provided some of the type material.

Remarks

H. kliei shares many taxonomic affinities with the H. pseudosarsi group of species. It is differentiated from all the other species of this group by having a more elongated habitus and correspondingly more distinctly elongated cephalosomic appendages and pereiopods. The marginal lobes of the female P5 exopod are undeveloped and are armed with thin elongated setae. These latter features are very distinctive and this provides good evidence that H. kliei is the same species Smirnov (1932) and Chislenko (1977) described as H. finmarchicum ( Scott, 1903) . In an earlier paper ( Clément & Moore, 2000) we have shown that the original description of H. finmarchicum by Scott (1903) has caused much confusion as it was based on material of two different species and so H. finmarchicum must be dropped from classification. We have also examined the material from which Willey (1920) described the female P5 of H. finmarchicum and we found that this too is ascribable to H. kliei .

The species described by Becker (1970) as H. finmarchicum and recorded from Germany is very distinct from H. kliei : the distal lobes of the P5 are well defined and the surface-seta does not extend beyond the exopod. Becker (1970) also noticed that in some specimens the distal lobes of the P5 exopod were devoid of spinules. Because of the complexities surrounding this group of species and the brief description given by Becker (1970), we cannot be certain of the identity of the species he recorded.

The distribution of H. kliei appears to be restricted to the Arctic seas. Smirnov (1932) and Chislenko (1977) recorded this species from Franz-Joseph Land.

Figures

Figure 11. Halectinosoma kliei sp. nov. Female holotype: A, habitus, dorsal; B, urosomites 2–6, ventral; C, urosomites 2–6, dorsal; D, P5. Male paratype: E, P5; F, P6.

Figure 12. Halectinosoma kliei sp. nov. Female holotype: A, antennule (setae omitted); B, antenna; C, coxal gnathobase of mandible; D, praecoxal arthrite of maxillula; E, maxilla; F, maxilliped. Male paratype: G, antennule (setae omitted).

Figure 13. Halectinosoma kliei sp. nov. Female holotype: A, P1; B, P2; C, P3; D, P4.