Goidelia pelliviva, Kim, 2000

Kim, Il-Hoi, 2000, Poecilostomatoid Copepods from an Intertidal Mud Flat in the Yellow Sea, Journal of Natural History 34 (3), pp. 367-432 : 393-402

Goidelia pelliviva n. sp.

( Figures 15 ±19)

Material examined. Twenty-three mm (including one ovigerous female), eight ll, one copepodid IV m, and one copepodid V m on the skin of an echiuroid ( T halassem a sp.) collected from the intertidal mud ¯at at Jakyak-do Island o Inchon, on 29 September 1996. Holotype (ovigerous m), allotype (l), and 26 paratypes (20 mm, six ll) have been deposited in the US National Museum of Natural History , Smithsonian Institution). Dissected specimens (two mm, one, l and copepodids) are kept in the collection of the author.

Female. Body (®gure 15A) small, 0.79 mm long. Greatest width 0.43 mm. Prosome very ¯at, oval in dorsal view, occupying about 70% of body length, and consisting of cephalothorax and three pedigerous somites. Urosome (®gure 15B, C) ®vesegmented. Fifth pedigerous somite 119 mm wide. Genital double- and ®rst two abdominal somites with ®ne striations on dorsal surface. Genital double-somite 71 (measured along median axis of ventral surface)Ö 126 mm, laterally expanded and well sclerotized. Genital area located ventrally (®gure 15C). Three abdominal somites 42 Ö70, 29 Ö55, and 25Ö 39 mm, respectively, with faint segmentation lines betwen them. Anal somite with spinules on posterior border of ventral surface. Anal operculum not discernible. Caudal ramus 29Ö 16 mm (1.81:1), with six setae. Inner dorsal seta plumose distally, but other setae naked. Inner one of mid-terminal setae 353 mm long, about three times as long as next longest, outer one of mid-terminal seta. Egg sac characteristically ¯at dorsoventrally, plate-like, eggs arranged in two layers, and 493Ö 193 mm.

Rostrum hardly di erentiated, leaving only faint sclerotized outline, broad, with truncate posterior margin. Antennule (®gure 15D) six-segmented, with armature formula 5, 13, 9, 4 +1 aesthetasc, 2 +1 aesthetasc, and 7 +1 aesthetasc. First seta on ®rst segment di erent from other setae, thick and densely hairy. All other setae naked. Antenna four-segmented, with armature formula 1, 0, 4 +1 claw, and 4 claws. Segmentation between third and fourth segments obscure. First segment longest. Basal two setae on third segment small, setule-like, and with same base; one of terminal setae plumose; claw on this segment pectinate distally, with 8±10 pectines. Claws on terminal segment di erent in length, outermost one longest and innermost one shortest, with number of pectines from inner to outer claws 6 or 7, 8 or 9, 5 or 6, 3±5, respectively.

Labrum covering only part of mouth parts, distally narrowed (®gure 15F), with concave posterior margin bearing ®ne spinules. Mandible with one thick terminal element bearing spinules on posterior margin. Paragnath as an unarmed lobe. Maxillule terminally with three setae, median one smaller, and outermost one plumose. Maxilla located lateral to mouth area (®gure 15F), two-segmented; ®rst segment highly sclerotized, strong, bearing one terminal and one subterminal hook (®gure 15F); second segment originating from proximal inner side of ®rst segment, a slender digitiform process bearing two terminal processes (or spinules). Maxilliped reduced to a triangular sclerotized rudiment.

Legs 1±4 with three-segmented rami, and with row of spinules on posterior margin of intercoxal plate, mid-posterior margin of basis, and outer margin of both rami (®gure 16A±E). Inner spine on basis of leg 1 short, not longer than width of endopodal ®rst segment. Spines of exopods setiform. Terminal seta on exopodal third segment of ®rst two legs and terminal two setae on same segment of legs 3 and 4 with spinules on outer side. Armature formula of legs 1± 4 as follows:

Leg 5 two-segmented. Basal segment well demarcated basally from ®fth pedigerous somite (®gure 15C), nearly quadrate, with one long seta on outer distal corner and one row of spinules on ventral surface. Distal segment (®gure 16F) elongate, 69Ö 40 mm (1.73:1), with four long setae and on ventral surface three obliquely transverse rows of spinules. Leg 6 represented by two small spinules on genital area (®gure 15C).

Male. Body (®gure 17A) resembling that of female. Length 0.41 mm. Greatest width 248 mm. Urosome six-segmented. Fifth pedigerous somite 94 mm wide, wider than genital somite, ventrally with one row of spinules on both sides. Posterodorsal border of ®fth pedigerous somite triangularly projected (®gure 17C). Genital somite much wider than long, 31 Ö 80 mm, nearly quadrangular, ventrally with one row of spinules along genital ¯ap. Four abdominal somites 25 Ö50, 22 Ö43, 17 Ö35, and 12 Ö 28 mm, respectively. Caudal ramus 16Ö 11 mm (1.45:1).

Antennule with one additional seta on third segment (at place of dark dot in ®gure 15D). Antenna sexually dimorphic. Third segment armed with two setae, one pectinated claw, and one long, sucker-bearing spine; claw with six or seven pectines; spine articulated basally, with one proximal larger sucker and row of nine minute suckers along one side of spine distal to larger sucker. Number of pectines of four claws on terminal segment, from inner to outer suckers, 5 or 6, 4 or 5, 3 or 4, and 2 or 3, respectively.

Mandible and maxillule as in female. Maxilla (®gure 17E) a ¯ap-like element bearing many spinules on ventral surface and one palp-like element (probably second segment) tipped by two unequal spinules. Maxilliped (®gure 17F) three-segmented. First segment unarmed. Second segment the largest, terminally with one setule; inner terminal corner bilobed. Third segment being a short, massive claw, beak-like, as long as width of second segment, with one lateral seta and two distal setules on each side.

Legs 1±4 as in female. Basal segment of leg 5 completely incorporated into somite, leaving only one seta (®gure 17B); free segment (®gure 17G) slender, 28 Ö 8.7 mm (3.22:1), with three setae on outer margin and one terminal spine; setae as long as or longer than segment, but spine slightly shorter than segment. Leg 6 represented by one large seta on posterior corner of genital somite.

Copepodid IV female. Body ( Fig 18A ) consisting of cephalothorax, three pedigerous somites, and four urosomites. Body length 394 mm. Genital double-somite and abdominal somites with one transverse row of spinules on ventral surface (®gure 18B).

Rostrum obscure, but with one pair of claw-like spines on ventral surface ( Fig 18C ). Antennule (®gure 18D) six-segmented, with armature formula: 4, 8, 7, 4 +1 aesthetasc, 2 +1 aesthetasc, and 7 +1 aesthetasc. Antenna (®gure 18E) foursegmented, with armature formula 1, 0, 4 +1 claw, and 3 claws; claw on third segment with six pectines; innermost claw of terminal segment bifurcate terminally, but other two claws simple.

Labrum, mandible, maxillule and maxilliped as in adult. First segment of maxilla terminated in one claw (®gure 18F).

Legs 1±4 (®gure 18G±J) with two-segmented rami and following armature formula:

Leg 5 represented by a small lobe tipped with two extremely unequal setae and one minute setule near posterior corners of ®fth pedigerous somite. Leg 6 not present.

Copepodid V female. Body (®gure 19A) nine-segmented, 525 mm. Rostral area more produced anteriorly. Urosome (®gure 19B) ®ve-segmented. First abdominal somite without spinules on ventral surface.

Antennule as in adult. Antenna (®gure 19C) with same armature formula as that of adult, but claws of terminal segment not yet completely developed.

Labrum, mouth parts, including maxilla (®gure 19D), as in copepodid IV.

Legs 1±4 fully developed. Leg 5 represented by a tapering lobe bearing ®ve setae of di erent lengths (®gure 19B).

Etymology. The speci®c name pelliviva is derived from the Latin pellis (= skin) and vivus (= living). It alludes to the fact that the new species is inhabiting the external surface of the host, unlike the only other known species Goidelia japonica Embleton, 1901 .

Remarks. Gooding (1963) recognized Goidelia Embleton, 1901 as a genus belonging to a group containing four other genera: Presynaptiphilus , Synaptiphilus , Myzomolgus , and Catinia . In the present report, Presynaptiphilus and Synaptiphilus are placed in a separate family Synaptiphilidae , and the three remaining genera in the Catiniidae . The unity of the Catiniidae is justi®ed by morphological similarities between the genera Catinia , Myzomolgus and Goidelia . The most typical morphological similarity is found in the maxilla which consists of a plate-like ®rst segment and a small, process-like second segment. Gooding (1963) was correct when he interpreted the`paragnath’ in Bocquet and Stock’s (1957) description of Catinia stupendus as the second segment. Closer similarity in the maxilla is found between those of Myzomolgus and Goidelia , in which this oral appendage bears an expanded, spinulated ®rst segment and the digitiform second segment tipped with two spinules. However, in Goidelia this form of maxilla is found only in the male. In the adult female of this genus, the ®rst segment of the maxilla is transformed into an appendage bearing distally two powerful hooks. This transformation occurs at the last moult from copepodid V to adult (cf: ®gures 15F and 19D).

The catiniid genera also show similarity in the antenna in which the third segment bears a large sucker. Again, this morphological feature is found in the female of Myzomolgus (male is unknown in this genus) and in both sexes of Catinia , but only in the male in Goidelia . Together with these characteristics, the ¯at, large prosome, small urosome, and the absence or reduction of the female maxilliped typify the Catiniidae . As a result of a cladistic analysis, Ho (1984) previously recognized the`catiniid complex’ to which he assigned Catinia , Myzomolgus , Goidelia , in addition to Cotylomolgus Humes and Ho, 1967 and Cotylemyzon Stock, 1982 (see Figures 4 , 5 and discussion of Ho, 1984). The sexual dimorphism in the antennule of Goidelia (addition of one aesthetasc on the third segment in the male antennule) is remarkable. Gooding (1963) also found a similar sexual dimorphism of the antennule in Catinia stupendus Bocquet and Stock.

Goidelia pelliviva n. sp. is the second species of the genus. The type species G. japonica was recorded from the alimentary canal of the echiuran, Urechinus unicinctus Embleton in Japan. Goidelia japonica can be easily collected in Korea from the same host, allowing a comparison of both species.

At ®rst, before examination of the copepodids of both species, the author was inclined to treat the new species as conspeci®c with the type species. However, the di erent ornamentation on the maxillae of copepodid V of both species (cf. ®gure 19D and E) con®rmed that they were not conspeci®c. The easiest way to distinguish between the two species is to compare body sizes, because Goidelia pelliviva n. sp. is distinctly smaller than G. japonica . The fully grown adult female of the latter is 1.26 mm long. Besides the smaller size, G. pelliviva , unlike G. japonica , bears spinules along the posteroventra l border of the female anal somite. In addition, the free segment of leg 5 of G. pelliviva is more slender than that of G. japonica . In spite of the prominent size di erence, distinction between the two species requires very careful comparison, since size is known to be a frequently unreliable taxonomic trait in copepods. This in turn indicates that members of Goidelia show quite a homogeneous morphology. The di erences between the two species may be summarized as in table 1.

The discovery of the new species from Korea, especially a female carrying egg sacs, leads to a reconsideration of the identity of the`male’ of Echiurophilus ®zei Delamare-Deboutteville and Nunes-Ruivo, 1955, a species found as an associate of an echiuroid from Viet Nam. Delamare-Deboutteville and Nunes-Ruivo (1955) described their species on the basis of ®ve females and one male. Later, Gooding (1963) suspected that the`male’ in the original description was an immature female.

It seems certain that the`male’ in the original description is a female, possibly of an unknown species of Goidelia , because the specimen shows an abdomen of less than four somites, a two-segmented leg 5 with well delimited basal segment, and, as noted by Gooding (1963), the absence of maxilliped. The well developed maxilla as illustrated in ®gure 5 of the original description (it is certain that the structure denoted as the maxilliped in the original description is in fact the ®rst segment of the maxilla) con®rms that the specimen is a mature female. Moreover, the discovery of a female of the new species bearing both the usual body form and egg sacs suggests that the species of Goidelia do not transform their body like that of Echiurophilus ®zei as Gooding had assumed.

It is worth mentioning here that I have examined more than several hundred adult females of Goidelia japonica collected from Korean seas, but an ovigerous female is yet to be discovered.

Figures

FIG. 15. Goidelia pelliviva n. sp., female: (A) habitus, dorsal; (B) urosome, dorsal; (C) same, ventral; (D) antennule; (E) antenna; (F) mouthparts. Scales: A =0.1 mm; B±D, F= 0.05 mm; E= 0.02 mm.

FIG. 18. Goidelia pelliviva n. sp, copepodid V, female: (A) habitus, dorsal; (B) urosome, ventral; (C) rostral area, ventral; (D) antennule; (E) antenna; (F) mouthparts; (G) leg 1; (H) leg 2; (I) leg 3; (J) leg 4. Scales: A = 0.1 mm; B±J= 0.02 mm.

FIG. 4. Clausia lobata n. sp., female: (A) habitus, dorsal; (B) urosome, dorsal; (C) same, ventral; (D) antennule; (E) antenna. Scales: A = 0.1 mm; B±C= 0.05 mm; D = 0.02 mm; E= 0.01 mm.

FIG. 5. Clausia lobata n. sp., female: (A) rostral area, ventral; (B) mouthparts; (C) mandible; (D) maxilliped; (E) leg 1; (F) leg 2. Scales: A = 0.05 mm; B, D±F= 0.02 mm; C= 0.01 mm.