Clausia lubbockii Claparède, 1863

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 : 8-12

publication ID	https://doi.org/ 10.11646/zootaxa.3651.1.1
publication LSID	lsid:zoobank.org:pub:2E9DC61F-00B8-42CF-BBB0-41651072F38C
persistent identifier	https://treatment.plazi.org/id/F473E52C-1C41-BB7D-059F-F9CE25A8EA95
treatment provided by	Felipe
scientific name	Clausia lubbockii Claparède, 1863
status

Treatment

Clausia lubbockii Claparède, 1863: 94 , pl. 17, figs. 7–14; Bocquet and Stock, 1960: 12, figs. 2–5.

Clausia uniseta Bocquet and Stock, 1960: 17 , figs.2–5. New synonym.

Material examined: 1 ♀, ovigerous (dissected and figured), from tube with Dipolydora flava (Claparède, 1870) ; Loch Sween , Scotland, SEPA Stn Mid Danna (55 o 56.44’N, 5 o 40.61’W), depth 16 m; collected by Stephen Nowacki, 04 June 2009 GoogleMaps .

1 ♀, ovigerous, from Dipolydora coeca (Oersted, 1843) agg. (= aggregate); Eastern English Channel , CEFAS Stn H9 a (50.41319 o N, 0.13736 o W), depth unknown (sample taken by Hamon Grab), August 2004; BMNH Reg. No. 2012.1369 GoogleMaps .

2 ♀ (1 ovigerous), Strangford Lough , Northern Ireland, EHS Stn Green Island (54 o 27.73'N, 05 o 36.64'W), depth 19.4 m; collected by Tim Mackie, 02 February 2009 GoogleMaps .

Female. Body ( Fig. 3A View FIGURE 3 ) elongate and consisting of 4-segmented prosome and 6-segmented urosome. Body length 2.04 mm. Prosome dorsoventrally depressed, slightly longer than urosome, and consisting of cephalothorax and 3 metasomal somites of similar widths. Cephalothorax 449×553 µm, metasomal somites 209×535, 196×553, and 246×541 µm, respectively. Fifth pedigerous somite 203×400 µm. Genital somite 173×342 µm, twice as wide as long; genital areas positioned dorsolaterally. Four free abdominal somites gradually narrowing from anterior to posterior ( Fig. 3C View FIGURE 3 ), 119×210, 120×205, 112×173, and 165×146 µm, respectively. Ventral surfaces of abdominal somites unornamented. Caudal rami divergent and widely separated from one another; each ramus ( Fig. 3D View FIGURE 3 ) tapering, 100×48 µm (ratio 2.08:1), armed with 7 smooth setae, including minute outer proximal seta (seta I); midterminal seta (seta V) much larger than other setae, more than 5 times as long as next longest seta III. Egg sac ( Fig. 3B View FIGURE 3 ) 2.63× 0.28 mm, about 1.5 times as long as body and containing 2 rows of eggs; each egg about 154 µm in diameter.

Rostrum ( Fig. 3E View FIGURE 3 ) anteriorly directed, broader than long, with pointed anterior apex; suture distinct between rostrum and dorsal cephalothoracic shield. Antennule ( Fig. 3E View FIGURE 3 ) 231 µm long, 6-segmented and gradually narrowing from proximal to distal; armature formula 4, 15, 10, 4, 2+aesthetasc, and 7+aesthetasc; setae on all segments naked. Antenna ( Fig. 3F View FIGURE 3 ) 3-segmented; first segment (coxa-basis) distally with 1 smooth seta and patch of setules; second segment (first endopodal segment) unarmed but ornamented with 2 patches of minute spinules on medial surface; terminal segment formed by fusion of second and third endopodal segments, 77×27 µm, armed with 1 claw and 2 setae (proximal seta minute) on medial margin, 4 claws of unequal sizes on distal margin, and 2 setae on outer side; ornamented with spinules on medial surface proximal to 3 medial elements and with small patch of spinules proximal to outer setae.

Labrum ( Fig. 3G View FIGURE 3 ) with strongly tapering posterior margin bearing pair of mid-distal membranous extensions; both sides of labrum ornamented with 2 patches of spinules. Mandible ( Fig. 3H View FIGURE 3 ) with 2 (distal and subdistal) spiniform elements; distal element with 9 denticles distally (proximalmost thicker than others) and subdistal element shorter than distal, with row of spinules along posterior (outer) margin. Maxillule ( Fig. 3I View FIGURE 3 ) lobate bearing 1 medial and 3 outer setae, one of latter bearing spinules on both margins. Maxilla ( Fig. 4A View FIGURE 4 ) 2-segmented; proximal segment unarmed but with bulla-like swelling covered with thin cuticle in middle of ventral surface; distal segment blunt, armed with 2 smooth setae (1 outer and 1 medial) and ornamented with dense distal covering of minute spinules and with rows of spinules in middle of segment. Maxilliped ( Fig. 4B View FIGURE 4 ) 3-segmented; first segment short and unarmed; second segment expanded in proximal half, with 2 naked setae on medial margin and patch of spinules on subdistal region; terminal segment blunt, with dense distal covering of minute spinules and on distal region of medial margin with 1 claw-like process and 2 small setae.

Legs 1 and 2 ( Fig. 4C, D View FIGURE 4 ) with 2-segmented rami; endopods distinctly shorter than exopods; all rami ornamented with spinules on outer surface. Inner seta on coxa of leg 1 rudimentary and transparent; that of leg 2 spiniform. Setae small on rami of legs 1 and 2. Leg 3 ( Fig. 4E View FIGURE 4 ) represented by 2 spinulose setae on lobe. Leg 4 absent. Armature formula of legs 1–3 as follows:

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

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

Leg 3: 2 on lobe.

Leg 5 ( Fig. 4F View FIGURE 4 ) directed dorsally and 2-segmented; proximal protopodal segment clearly defined from somite, with 1 small dorsodistal seta; distal segment (exopod) 135×62 µm (ratio 2.18:1), armed with 4 unequal setae and ornamented distally with patches of minute spinules. Leg 6 represented by 1 small simple seta in genital area ( Fig. 3C View FIGURE 3 ).

Remarks. Bocquet and Stock (1960) redescribed this species based on a female found on a compound ascidian Didemnum fulgens (Milne-Edwards, 1841) inhabited by several polychaetes. Our discovery of two females of this copepod from spionid polychaetes of the genus Dipolydora indicates that the real host of this copepod is the polychaete, as suggested by Gotto (1993). The specimen from Loch Sween was found alongside its host and was located at setiger 16, with its anterior orientated towards the host anterior.

The dissected specimen shows no significant differences from the redescription of Bocquet and Stock (1960). The labrum is described for the first time and the exact setation patterns of the antennule, antenna and maxilliped are presented here. The lobate leg 3 of one of the ovigerous specimens from Strangford Lough has only a single seta but otherwise resembles the figured specimen.

Until now Clausia lubbockii has only been recorded from the Channel coast of France at Saint Vaast-la- Hougue and Roscoff, and from the coast of Norfolk, England. A very similar species, Clausia uniseta Bocquet & Stock, 1960 was described from a single female, collected on the coast of Norfolk, England. The establishment of C.uniseta is based mostly on minor differences in setal length and on the presence of only a single seta on leg 3. C. lubbockii has also been recovered from the exact same site as C.uniseta ( Hamond, 1973) and, as noted above, exhibits variation with either two or only a single seta present on leg 3. We consider that the maintenance of C.uniseta as a separate species is unjustified and propose to treat it as a synonym of C. lubbockii . With the transfer of C. antiqua Kim, 2001 and C. lobata Kim, 2000 to Pontoclausia Băcescu & Por, 1959 by Ho & Kim (2003), the genus now comprises only C. lubbockii .