Sigecheres concinna (T. Scott, 1902 ) 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 : 44-46

Sigecheres concinna (T. Scott, 1902) new combination

Nereicola concinna T. Scott, 1902: 455–456 , pl. XXV, figs 8–14.

Sigecheres brittae Bresciani, 1964b: 297 , figs. 1, 2.

Material examined: 1 ♀ (dissected) from Sige fusigera ; Brattholmen, FFH 3958, Stn B2A (65.914ºN, 12.2204ºE), depth 102 m; 23 March 2007.

Female. Body ( Fig. 25A ) consisting of 3 divisions: cephalosome, trunk, and 1-segmented urosome, Body length 1.37 mm. Cephalosome nearly circular, 390×548 µm, defined from trunk by distinct constriction. Trunk subrectangular, 850×850 µm, as long as wide. Abdomen ( Fig. 25B ) strongly tapering, 185×369 µm, with deep posteromedial cleft. Caudal ramus ( Fig. 25C ) small, 192×150 µm, with 6 naked setae, one much larger than other 5. Genital areas located ventrally. Egg sac 1.22× 0.45 mm.

Rostrum not discernible ( Fig. 25D ). Antennule ( Fig. 25E ) 188 µm long and 5-segmented; armature formula 3, 8, 4+aesthetasc, 2+aesthetasc, and 7+aesthetasc; all setae naked. Antenna ( Fig. 25F ) 4-segmented; first segment large but unarmed; second segment with patch of spinules on mediodistal surface; third segment with 1 blunt spinulose spine and 1 small seta; terminal segment incompletely defined from third segment, with 2 proximal setae and 4 unequal distal spines bearing spinules distally.

Labrum ( Fig. 25G ) with patch of spinules on each ventrolateral surface and prominent, funnel-like posteromedian extension enclosing mandible ( Fig. 25D ). Mandible ( Fig. 25H ) simple, with 12 or 13 teeth arranged along distal margin. Maxillule ( Fig. 25I ) digitiform, with 1 large, spinulose outer lateral and 3 distal setae. Maxilla ( Fig. 25J ) 1-segmented and characteristic in bearing large hollow functioning as sucker (pieces of detached host tissue were held within this sucker), with circular, saw-like apparatus in hollow. Maxilliped ( Fig. 25K ) 3- segmented; all segments unarmed; terminal segment with spinulose pad on truncated distal surface.

Legs 1–6 absent.

Male. Unknown.

Remarks. T. Scott (1902) described a new species of Nereicola Keferstein, 1863 , N. concinna , from a phyllodocid polychaete Eulalia viridis Linnaeus, 1767 (as Eulalia viridis Oersted ) collected at a depth of 100–119 m (55–65 fathoms) in Loch Etive on the west coast of Scotland. His description was detailed, showing the adult ovigerous female, the antennule, antenna, mandible, maxilla and maxilliped, as well as an “immature specimen”. We find no significant differences between our material and the description of Scott (1902). As suspected by Gotto (1993), Nereicola concinna is conspecific with Sigecheres brittae as described by Bresciani (1964b). The copepod redescribed here was collected from the mid-body region of the same phyllodocid polychaete, Sige fusigera , as in the original description of the species ( Bresciani, 1964b). Both Sige fusigera and Eulalia viridis belong to the same subfamily, Eteoninae , of the Phyllodocidae . Some minor emendations to the original description are made here with regard to the structure of maxilla, the segmentation of the antenna, and the setation of the caudal ramus and antennule. Bresciani (1964b) pointed to the peculiar form of the maxilla having an excavation. This appendage, acting as a sucker, is the most striking, autapomorphic feature of the genus in comparison with the usual structure of the two-segmented maxilla—with the stout distal segment having a spinulose pad or spiniform elements as found in other genera of Nereicolidae .

We consider that Bresciani (1964b) made a strong case for the classification of this parasite as a distinct genus within the Nereicolidae , and we follow this treatment here. The oldest available name for this taxon is Sigecheres concinna (T. Scott, 1902) , new combination, and S. brittae becomes a junior subjective synonym. Nereicola remains monotypic and its type species Nereicola ovata Keferstein, 1863 was redescribed by Laubier in 1965.

Genus Anomopsyllus Sars, 1921

Figures

FIGURE 25. Sigecheres concinna (T. Scott, 1902) new combination, female. A, habitus, dorsal; B, abdomen, ventral; C, right caudal ramus, ventral; D, anterior part of cephalothorax, ventral; E, antennule; F, antenna; G, labrum, ventral; H, mandible; I, maxillule; J, maxilla; K, maxilliped. Scale bars: A, 0.2 mm; B, 0.1 mm; C, E–K, 0.02 mm; D, 0.05 mm.