Spiophanicola atlanticus, 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 : 54-57

Spiophanicola atlanticus n. sp.

Spiophanicola spinosus: O’Reilly (1999: 46–47)

Type material: Holotype ♀ from Spiophanes kroeyeri Grube, 1860 ; Motovsky Gulf, Stn 22-5 (69°33.266’N, 32°52.171’E), depth 218 m, 11 August 2003; BMNH Reg. No. 2012.1413.

Paratype ♀ (dissected and figured) from S. kroeyeri ; off northeastern coast of Svalbad, Prosj. 2302, Stn 8-3 (80.118ºN, 8.778ºE), depth 512 m, 20 May 2003; BMNH Reg. No. 2012.1414 .

Paratype ♀ (dissected) detached parasite from unknown host; Hinlopenstretet, Svalbad, Stn VI (78.718ºN, 18.332ºE), depth 433 m, 17 August 2003; BMNH Reg. No. 2012.1415 .

Paratype ♀ detached parasite from unknown host; 10 miles off Cullercoats , Northumberland, depth 80 m, Coll. Peter Garwood; BMNH Reg. No. 1999.165 (reported by O’Reilly, 1999) .

Paratype ♀ from S. kroeyeri ; northern North Sea , depth unknown, collected by M. Sheader; BMNH Reg. No. 1999.471 .

Paratype ♀ from S. kroeyeri ; northern North Sea , depth unknown, BMNH 2005.2085

Additional material: 1 ♀ from anterior dorsum of S. kroeyeri , off Northumberland, England, CEFAS Stn 57A (55 o 01.189’N, 01 o 14.960’W), depth 55 m, collected by P. Garwood (possibly 1999); BMNH Reg. No. 2012.1416 .

1 tiny copepodid on juvenile S.kroeyeri from inner Firth of Clyde , Scotland, off Cloch Point, SEPA Stn CMT7 (55 o 56.85’N, 04 o 53.65’W), depth 80 m; collected by M.O’Reilly, 11 May 2000; BMNH Reg. No. 2012.1417 .

2♀ ovigerous from S.kroeyeri from inner Firth of Clyde , Scotland, off Cloch Point, SEPA Stn CMT7 (55 o 56.85’N, 04 o 53.65’W), depth 80 m; collected by M.O’Reilly, 13 March 2002; BMNH Reg. No. 2012.1418-1419 .

1♀ detached from host, inner Firth of Clyde , Scotland, off Cloch Point, SEPA Stn CMT7 (55 o 56.85’N, 04 o 53.65’W), depth 80 m, collected by M.O’Reilly, 28 April 1999; BMNH Reg. No. 2012.1420 .

1♀ on S.kroeyeri & 1♀ detached from host, inner Firth of Clyde , Scotland, off Cloch Point, SEPA Stn CMT7 (55 o 56.85’N, 04 o 53.65’W), depth 80 m; collected by M.O’Reilly, 13 April 2004 .

1♀ on S.kroeyeri outer Firth of Clyde , Scotland, at SEPA Stn 10 km E. of Johnston’s Point (55 o 19.44’N, 05 o 21.01’W), depth 48 m; collected M.O’Reilly, 30 November 2010 .

Female. Body ( Fig. 30A ) elongate and dorso-ventrally flattened. Body length of dissected specimen 1.88 mm. Cephalosome clearly separated from trunk. Trunk consisting of 5 metasomal somites (first to fifth pedigerous somites); each somite defined by weak constrictions. Genital complex slightly wider than long. Abdomen 1- segmented, longer than wide, 125×105 µm. Caudal ramus elongate, 113×37 µm (ratio 3.05:1), with 5 setae ( Fig. 30B ).

Rostrum absent. Antennule ( Fig. 30C ) 6-segmented; armature formula 3, 9, 2+aesthetasc, 2+aesthetasc, 2, 2+aesthetasc, and 7+aesthetasc; anterodistal projection on first segment terminating in acute tip, with 1 large, spiniform subdistal seta. Antenna ( Fig. 30D ) 4-segmented: first segment with distal spine on inner margin; second segment with 1 small proximal seta; third segment with 2 distal setae and 3 spinulose lobes.

Labrum ( Fig. 30E ) with posteromedian protrusion. Mandible with 1 slender, spiniform distal element articulated at base ( Fig. 30F ). Paragnath forming spinulose lobe ( Fig. 30F ). Maxillule lobate, bearing 2 setae ( Fig. 30F ). Maxilla ( Fig. 30G ) distinctly 2-segmented; proximal segment with 1 mediodistal seta; spinulose distal segment elongate and unarmed. Maxilliped ( Fig. 30H ) 4-segmented: first and second segments each with 2 setae distally on medial margin; third segment unarmed; terminal segment forming strongly recurved hook, armed with 3 small setae; first to third segments each with patches of fine spinular ornamentation on medial surface, terminal hook with spinules on outer surface.

Legs 1–4 ( Figs 30I , 31A–C ) biramous; each comprising protopod partly incorporated into somite, bearing outer seta, partly fused exopod and distinct endopod: exopod of legs 2 to 4 markedly longer than corresponding endopod: exopod of all legs bearing single inner margin seta and having spinulate apex; endopod of leg 1 with 5 setae, legs 2, 3 and 4 each with 3 setae. Leg 5 ( Fig. 30J ) consisting of 1 small papilla tipped by 2 small setae and 1 nearby seta. Leg 6 not observed.

Male. Unknown.

Etymology. The specific name atlanticus is derived from the type locality, as distinct from the Pacific distribution of its only congener.

Remarks. Spiophanicola spinulosus Ho, 1984 was described based on specimens associated with three species of polychaetes belonging to the genus Spiophanes from the Pacific coast of North America ( Ho, 1984). It was subsequently reported from British waters from Spiophanes kroeyeri , and possibly from Spiophanes bombyx (Claparède, 1870) ( O’Reilly, 1999) .

There are several differences between the northern European specimens described here and the type material from California used in the original description. In our specimens the anterodistal projection of the first antennular segment terminates in a simple angle whereas it terminates in a distinct hook-like structure in the type specimens. The maxilla is distinctly 2-segmented in our material but the types were described as having unsegmented maxillae ( Ho, 1984). There are significant differences in the endopodal setation of legs 1 and 4 which are armed with 5 and 3 setae respectively in our European material, compared with 4 and 2 setae, respectively, in the types. In addition there are differences in the proportional lengths of the rami in legs 3 and 4: in the European material the exopods are distinctly longer than the endopods whereas in the Californian type specimens the exopods are markedly shorter. Finally, leg 5 is better developed in the type material: it is bilobed and the lobes are tipped with 1 or 2 apical setae. In comparison in the new material described here, leg 5 is represented by a papilla bearing 2 setae plus an adjacent isolated seta on the somite surface nearby .

Differences between the European material and the Californian type material were previously considered to represent variation in a parasite species found on the same host, the polychaete S. kroeyeri , in both the Pacific and the Atlantic. However, after examination of new European material and re-examination of one of the specimens (BMNH 1999.165) reported by O’Reilly (1999), we recognise consistent differences between the type material and the European material. We now consider these differences to be significant and propose to establish a new species for the northern European material.

The recognition of S. atlanticus n. sp. as a sister species of S. spinulosus should prompt the removal of the latter species name from the list of alien and invasive species in European Seas ( Olenin & Didžiulis, 2009; DAISIE, 2009; Noël, 2011). The wide distribution of S. atlanticus n. sp. from Norwegian waters to the central North Sea and the west coast of Scotland suggests that this is merely a hitherto overlooked European species rather than an alien.

Family uncertain

Figures

FIGURE 30. Spiophanicola atlanticus n. sp. female. A, habitus, dorsal; B, posterior part of body, ventral; C, antennule; D, antenna; E, labrum, ventral; F, mandible, paragnath and maxillule; G, maxilla; H, maxilliped; I, leg 1; J, leg 5. Scale bars: A. 0.2 mm; B, 0.1 mm; C, D, H, J, 0.05 mm; E–G, I, 0.02 mm.

FIGURE 31. Spiophanicola atlanticus n. sp. female. A, leg 2, B, leg 3; C, leg 4. Scale bars: 0.02 mm for all.