Boreoclausia holmesi, Kim & Sikorski & O’Reilly & Boxshall, 2013

Kim, Il-Hoi, Sikorski, Andrey, O’Reilly, Myles & Boxshall, Geoff A., 2013, Copepods associated with polychaete worms in European seas, Zootaxa 3651 (1), pp. 1-62 : 35-38

Boreoclausia holmesi n. gen. et n. sp.

Type material: 3 ♀ (intact holotype and 1 paratype and 1 dissected paratype) from Myriochele danielsseni ; Loch Hourn , Scotland; collected by P. Garwood, 11 May 2005. BMNH Reg. No. 2012.1387 (Holotype) and BMNH Reg. No. 2012.1388 (Paratype) .

Paratype ♀ from Myriochele / Galathowenia fragment; Sample C2B, Selivoe, Shetland [either inner site, 60 o 12.567’N, 01 o 23.909’W, depth 11 m, or outer site 60 o 11.752’N, 01 o 24.061’W, depth 8–21 m], collected by P. Garwood, July 2000; BMNH Reg. No. 2012.1389.

Paratype ♀ from unknown host; East Shetland basin (61 o 27.79’N, 01 o 17.82’E), depth 178 m; collected by P. Garwood, 26 July 2007; BMNH Reg. No. 2012.1390 .

Female (dissected paratype). Body ( Fig. 19A ) elongate, dorsoventrally depressed, with parallel lateral margins, and consisting of cephalosome, first to fifth pedigerous somites, genital complex and 1-segmented abdomen. Body length 1.41 mm. Prosome-urosome division not marked. Cephalosome 308×260 µm, with anteriorly produced rostral area. Lengths of first to fifth pedigerous somites 104, 81, 185, 200, and 196 µm, respectively. Second to fourth pedigerous somites each with rudimentary tergite along posterodorsal border of somite; each tergites ornamented with transverse row of fine spinules near posterior margin. Anterior hoop-like part of genital complex partially separated as short (77 µm long) pseudosomite ( Fig. 19A ). Genital complex 123×185 µm, parallel-sided but narrowing in posterior third; genital apertures located dorsolaterally at midlength ( Fig. 19B ). Single-segmented abdomen 81×69 µm, with parallel lateral margins. Caudal ramus 60×27 µm (ratio 2.22:1), with 6 setae; longest terminal seta about 140 µm long, more than twice as long as ramus.

Rostrum as anterior prominence on cephalosome. Antennule ( Fig. 19C ) 5-segmented but first segment with suture line on dorsal surface; armature formula 12, 2, 2, 2+aesthetasc, and 7+aesthetasc; first segment expanded; setae on first segment usually small. Antenna ( Fig. 19D ) 4-segmented; first segment unarmed; second segment also unarmed but with patch of spinules on medial surface; third segment with 1 thick, spinulose spine, 1 seta, and 2 patches of spinules; terminal segment 17×14 µm, with 1 thick, spinulose spine and 4 simple setae.

Labrum ( Fig. 19E ) with straight posterior margin and ornamented with several patches of minute spinules posteriorly on ventral surface. Mandible ( Fig. 19F ) tapering distally, with 1 spiniform apical process; process not articulated at base but with membranous flange along medial (anterior) margin. Maxillule ( Fig. 19G ) lobate, with 1 inner and 2 outer setae distally. Maxilla ( Fig. 19H ) 2-segmented; proximal segment unarmed; distal segment blunt, with 1 proximal seta and distal spinulose pad. Maxilliped ( Fig. 19I ) 4-segmented; first segment broad and unarmed; second segment longest, with 1 naked seta subdistally; short third segment unarmed; fourth segment with 1 stout spinulose lateral spine and blunt apex bearing spinulose pad.

Legs 1 and 2 ( Figs 20A, B ) with 2-segmented exopod and small, lobate endopod, ornamented with patch of spinules in leg 1, smooth in leg 2. Leg 3 ( Fig. 20C ) with 2-segmented exopod but lacking endopod. Leg 4 ( Fig. 20D ) a lobe bearing 1 outer lateral and 0–2 distal setae. Spines on exopod of legs 1–3 massive and spinulose. Outer margin of first exopodal segment of legs 1–3 ornamented with spinules. Armature formula of legs 1–3 as follows:

Leg 1: coxa 0-0; basis 1-0; exp. I-0; II, I, 1; enp. (lobe)

Leg 2: coxa 0-0; basis 1-0; exp. I-0; II, I, 0; enp. (lobe)

Leg 3: coxa 0-0; basis 1-0; exp. 0-0; II, I, 0; enp. (lacking)

Leg 5 absent. Leg 6 represented by 1 seta and 2 spinules in genital area ( Fig. 19B ).

Male. Unknown.

Etymology. The specific name honours Dr J.M.C. (Mark) Holmes (National Museum of Ireland, Dublin) in recognition of his contributions to the taxonomy of associated copepods. Dr. Holmes sent us sketches some years ago of an undescribed copepod, which appears to be identical to B. holmesi , and was found on Owenia fusiformis Della Chiaje, 1844 collected near San Sebastian, Spain.

Remarks. Boreoclausia holmesi n. sp. is placed in the same genus as B. recta n. sp. as it shares numerous important attributes (see generic diagnosis). B. holmesi n. sp. can be distinguished from B. recta n. sp. by the following differences: there are no lateral constrictions on the fourth and fifth pedigerous somites; the fifth pedigerous somite does not have a rudimentary dorsal tergite; the antennule is five-segmented; the distal blade on the mandible is fused rather than articulated at its base as in B. recta n. sp.; the maxilliped has a massive spine instead of a seta on the terminal segment; the first to third legs have different armature on the distal exopodal segment (3 spines+1 seta in leg 1, and 3 spines in both legs 2 and 3 in contrast to 2 spines+2 setae in leg 1 and 1 spine+1 seta in both legs 2 and 3 in B. recta n. sp.) and leg 5 is absent.

Figures

FIGURE 19. Boreoclausia holmesi n. gen. et n. sp., female. A, habitus, dorsal; B, genital double-somite and abdomen, dorsal; C, antennule, ventral; D, antenna; E, labrum, ventral; F, mandible; G, maxillule; H, maxilla; I, maxilliped. Scale bars: A, B, 0.1 mm; C–I, 0.02 mm.

FIGURE 20. Boreoclausia holmesi n. gen. et n. sp., female. A, leg 1; B, leg 2; C, leg 3; D, leg 4. All scale bars: 0.02 mm.