Vectoriella gabesensis, 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 : 52-54

Vectoriella gabesensis n. sp.

Type material: Holotype ♀ (intact) from Aricidea catherinae ; Gulf of Gabes, Tunisia (~ 33 o 50.26’N, 10 o 36.38’E), depth 13 m, found by David Hall, 28 October 2004; BMNH Reg. No. 2012.1406.

2 ♂♂ (allotype ♂ intact and 1 ♂ dissected paratype) from A. catherinae ; Gulf of Gabes, Tunisia, (~ 33 o 50.26’N, 10 o 36.38’E), depth 13 m, found by David Hall, 28 October 2004; BMNH Reg. No. 2012.1407 (intact), BMNH Reg. No. 2012.1411 (dissected)..

4 paratype ♀ (1 ♀ dissected; 3 ♀ partly damaged) from A. catherinae ; Gulf of Gabes, Tunisia, (~ 33 o 50.26’N, 10 o 36.38’E), depth 13 m, found by David Hall, October 2004; BMNH Reg. No. 2012.1408-1410 (undissected), BMNH Reg. No. 2012.1412 (dissected) .

Etymology. The specific name is derived from the type locality, the Gulf of Gabes, Tunisia, in the Mediterranean Sea.

Female. Body ( Fig. 29A ) consisting of weakly defined cephalosome, large inflated trunk, and 2-segmented urosome. Body length 508 µm, excluding caudal setae. Cephalosome defined from trunk only by slight lateral constriction. Trunk flattened, about 435×275 µm, slightly broadening posteriorly, with weakly concave lateral margins near middle of trunk. Urosome ( Fig. 29B ) consisting of genital complex and 1-segmented abdomen. Genital complex much wider than long; genital apertures large and located ventrally ( Fig. 29B ). Abdomen about 1.5 times as long as wide. Caudal ramus ( Fig. 29C ) weakly tapering, 39×14 µm (ratio 2.79:1), with 5 naked setae.

Rostrum absent. Antennule ( Fig. 29D ) 5-segmented, with armature formula 2, 7, 2, 1+aesthetasc, and 4; all of setae simple and naked. Antenna ( Fig. 29E ) rudimentary, lobate with 2 setae (one small and process-like), and 1 distally bifurcate spine.

Labrum ( Fig. 29F ) with tapering lateral margins and 2 nipple-shaped processes near concave posteromedial margin. Mandible ( Fig. 29G ) with 1 large, plate-like distal element covered by spinules. Paragnath ( Fig. 29H ) as spinulose lobe. Maxillule ( Fig. 29I ) lobate, with 5 thick setae distally. Maxilla ( Fig. 29J ) 2-segmented; proximal segment unarmed; distal segment with 3 blunt spinulose spines. Maxilliped ( Fig. 29K ) 3-segmented; first segment unarmed; second segment with 1 medial seta; third segment unarmed, gradually narrowed distally, with truncate tip covered by spinules.

Leg 1 represented by pair of blunt setae anteriorly on ventral surface of trunk ( Fig. 29A ). Legs 2 and 3 each represented by 1 blunt seta ( Fig. 29A ). Legs 4 and 5 absent. Leg 6 represented by 2 small setae in genital area ( Fig. 29B ).

Male. Body ( Fig. 29L ) evenly tapering from anterior to posterior and consisting of 7 incompletely articulated somites. Body length 385 µm excluding caudal setae. Maximum width 111 µm. First tagma (cephalothorax) incorporating cephalosome and first and second pedigerous somites. Cephalosomic area of cephalothorax expanded, forming widest part of body. Free abdomen 2-segmented. Anal somite distinctly longer than preceding free abdominal somite. Caudal ramus 58×13 µm (ratio 4.46:1), with 5 setae; medial terminal seta longest, 161 µm long.

Rostrum absent as in female. Antennule segmented as in female but with different armature formula: 2, 7, 3+aesthetasc, 1+aesthetasc, and 4+aesthetasc. Antenna as in female. Labrum ( Fig. 29M ) sexually dimorphic, directed anteriorly and extending beyond frontal margin of cephalothorax ( Fig. 29L ), bearing pair of flat, wedgelike elements. Other mouthparts, including maxilliped, as in female.

Leg 1 bilobed: larger outer lobe with 2 setae, smaller inner lobe (endopod) unarmed ( Fig. 29L ). Legs 2 and 3 with 1 seta on outer lobe and unarmed inner lobe, Legs 4 and 5 absent. Leg 6 each represented by 2 setae on posterior corner of genital flaps closing off paired genital apertures ( Fig. 29L ).

Remarks. Two species are currently known in the genus Vectoriella : both are associates of polychaetes of the family Paraonidae : V. marinovi Stock, 1968 associated with Aricidea (Acmira) cerrutii Laubier, 1966 (as Aricidea jeffreysii (McIntosh)) from the Black Sea ( Stock, 1968) and V. ramosae Laubier and Carton, 1973 associated with Aedicira mediterranea Laubier and Ramos, 1974 (as Aricidea (Aedicira) mediterranea ) from the Mediterranean Sea ( Laubier and Carton, 1973). Several of the females had remnants of ovisacs and were attached dorsally on their hosts around setiger 14 or 15. The head of the copepod was directed towards the anterior of the worm.

Vectoriella gabesensis n. sp. is more similar to V. marinovi than to V. ramosae in having a female abdomen that is longer than wide, five caudal setae in the female, three spiniform elements on the distal segment of the maxilla, and the anteriorly projecting male labrum bearing a pair of wedge-like elements. It is notable that Stock (1968) misinterpreted the male labrum as the rostrum, presumably because it forms a rostrum-like anterior protrusion which extends beyond the anterior margin of cephalothorax. It originates from the region posterior to the antenna.

The new species is distinguishable from V. marinovi by the following character states: 1) the caudal ramus of V. gabesensis n. sp. is 2.79 times longer than wide in the female and 4.46 times as long as wide in the male, compared to 4.5 times in the female and 6 times in the male of V. marinovi ( Stock, 1968) ; 2) the antenna of V. gabesensis n. sp. bears 2 setae and 1 spine, unlike that of V. marinovi which bears 2 setae only; 3) the terminal (third) segment of the maxilliped, which exhibits no sexual dimorphism, bears only a spinulose pad distally in V. gabesensis n. sp., unlike that of V. marinovi which bears two pectinate elements; 4) legs 1–3 of V. gabesensis n. sp. are represented by 1 or 2 setae in the female but those of V.marinovi are biramous, although the rami are feebly developed.

Figures

FIGURE 29. Vectoriella gabesensis n. sp. female: A, habitus, ventral; B, urosome, dorsal; C, left caudal ramus, dorsal; D, antennule; E, antenna; F, labrum; G, mandible; H, paragnath; I, maxillule; J, maxilla, ventral; K, maxilliped. Male: L, habitus, ventral; M, labrum, posterior. Scale bars: A, 0.1 mm; B, L, 0.05 mm; C, F, M, 0.02 mm; D, E, G–K, 0.01 mm.