Desmoscolex Claparède, 1863

Rho, H. S., Kim, W. & Chang, C. Y., 2007, Description of two new free-living marine nematode species of the subgenus Desmolorenzenia (Desmoscolecida, genus Desmoscolex) from Korea, Journal of Natural History 41 (5 - 8), pp. 313-326 : 315-319

publication ID	https://doi.org/ 10.1080/00222930601176571
persistent identifier	https://treatment.plazi.org/id/0384879C-6F72-FFA8-FE51-37FCFD58FDFE
treatment provided by	Carolina
scientific name	Desmoscolex Claparède, 1863
status

Treatment

Genus Desmoscolex Claparède, 1863

Subgenus Desmolorenzenia Freudenhammer, 1975 Desmoscolex (Desmolorenzenia) coreensis sp. nov.

( Figures 2 View Figure 2 , 3 View Figure 3 )

Type material

Holotype male ( RIT699 ) and one paratype (juvenile female) ( RIT700 ), mounted in glycerine on H-S slide, are deposited in the nematode collection of the Royal Belgian Institute of Natural Sciences, Brussels, Belgium. Three paratypes (one male and two juvenile females) (DB30002-30004) are deposited in the nematode collection of the Department of Biology , Daegu University , Korea. Another six paratypes (one male and five juvenile females) (SNU10005-10010) are kept in the first author’s (H. S. Rho) research collection at the School of Biological Sciences , Seoul National University, Korea.

Type locality

Geomundo Island (34 u 059320 N, 127 u 149550 E), collected on 6 October 2001 by H. S. Rho and J. W. Choi.

Type habitats

The nematodes were obtained from sponges and bryozoans on subtidal rocks (25 m deep), collected by scuba diving.

Etymology

The specific name, coreensis , alludes to the type locality of the new species.

Measurements

Holotype male: L5480; hd527; cs522; sd 1517; sd 3517; sd 7517; sd 9521; sd 11521; sd 13519; sd 16521; sd 17525; sv 2513; sv 4514; sv 6516; sv 8513; sv 10514; sv 12516; sv 14519; sv 15516; ph578; t590; tmr549; tmrw521; mbd576; mbde563; spic546; gub510; a56.3; c55.3.

Paratype males (n 52): L5370–420 (395); hd526–27; cs514–17; sd 1517; sd 3519 –21; sd 5517 –21; sd 7515; sd 9519; sd 11519 –21; sd 13518 –21; sd 16520 –21; sd 17524 –25; sv 2513; sv 4515 –16; sv 6513 –15; sv 8515; sv 10517; sv 12516; sv 14515 –20; sv 15515; ph568; t575–86; tmr543–56; tmrw522–23; mbd563–71; mbde554–59; spic542–43; gub59; a55.2–6.7; b56.2; c54.9.

Juvenile females (n 56): L5420–465 (441); hd523–29; cs515–19; sd 1519 –20; sd 3516 – 18; sd 5517 –18; sd 7516 –23; sd 9518 –20; sd 11519 –20; sd 13519 –24; sd 16520 –21; sd 17522 –28; sv 2513 –17; sv 4517; sv 6515 –17; sv 8515 –17; sv 10515 –17; sv 12514 –18; sv 14515 –19; sv 15516 –17; ph575; t573; tmr546–53; tmrw522–26; mbd559–71; mbde549–61; a56.6–7.6; b56; c56.2.

Description

Males. Body short, ventrally curved ( Figures 2A View Figure 2 , 3A View Figure 3 ), slightly tapered towards the anterior and posterior. Cuticle ( Figures 2A View Figure 2 , 3A View Figure 3 ) with 17 desmens. Desmen quadricomoid with inversion in orientation at level of desmen 14. Each desmen consisting of a layer of secretion and finely granular foreign material (5 desmos) on annulated body cuticle.

Somatic setae ( Figure 2A View Figure 2 ) arranged according to the typical desmoscolecid setal pattern: nine pairs of subdorsal setae on desmens 1, 3, 5, 7, 9, 11, 13, 16, 17; eight pairs of subventral setae (located somewhat lateroventrally) on desmens 2, 4, 6, 8, 10, 12, 14, 15. Subdosal setae with fine mid-central canal, gradually tapered to an open tip; external opening of tip oval-shaped. Subdorsal somatic setae inserted without peduncle on body cuticle, and longer than subventral somatic setae. Posteriormost pair of subdorsal somatic setae slightly longer. Subventral somatic setae ( Figure 2A View Figure 2 ) inserted somewhat lateroventrally; setae small and relatively stumpy with fine mid-central canal; cylindrical basal part broad and tapering distally, without differentiated apical part. Subventral somatic setae all about same length (except slightly longer seta on desmen 14), inserted almost directly into cuticular rings without peduncle.

Head wider than long, rounded ( Figures 2A View Figure 2 , 3A, B View Figure 3 ), anteriorly tapered and truncated, and posteriorly with more or less cylindrical neck-region. Head cuticle completely covered with thin layer of fine granular desmos, except in amphideal zone. Labial region not distinct, apparently without separate lips. Labial sensilla not observed. Cephalic setae, 22 mm long, shorter than head width; jointed distally, i.e. finer distal part socketed into broad, cylindrical basal part near the tip of setae ( Figure 2A, C, E View Figure 2 ); setae inserted directly on head cuticle just anterior to mid-head. Amphideal fovea ( Figures 2A View Figure 2 , 3B, C View Figure 3 ) rounded, largely covering head laterally; extending anteriorly to truncated end and posteriorly beyond level of insertion of cephalic setae. Small buccal opening leading to thin-walled stoma, 7 mm in length. Oesophagus not observed in holotype, but extending to end of desmen 3 in paratypes ( Figure 2C View Figure 2 ).

A pair of oval (18 mm 68 mm long), dark yellowish ocelli situated between desmens 3 and 4 ( Figure 2A View Figure 2 ). Digestive system typical of Desmolorenzenia . Reproductive system typical of Desmoscolecidae . Single testis outstretched, extending anteriorly up to level between desmens 9 and 10 ( Figure 2A View Figure 2 ). Ejaculatory glands not observed. Spicules 46 mm long ( Figure 2A, B View Figure 2 ), nearly straight; corpus tapering caudally to pointed tip and proximally adjacent with poorly developed, offset capitulum. Gubernaculum 10 mm long, adjacent to tip of spicules. Cloacal tube broad, clearly protruded from medioventral body wall in desmen 15 ( Figure 2A, B View Figure 2 ).

Tail consisting of two desmens ( Figures 2A View Figure 2 , 3D View Figure 3 ). End ring, 49 mm long, about 2.3 times longer than wide, consisting of broad cylindrical anterior part, extending up to insertion of terminal subdorsal somatic setae, and ventrally bent posterior part, tapering towards short, uncovered spinneret. End ring, with exception of terminal spinneret, totally covered with layer of secretion and foreign material. Caudal glands not observed.

Juvenile females. Similar to males in most respects. Body short, ventrally curved ( Figure 2D View Figure 2 ). Cuticle ( Figure 2D, E View Figure 2 ) with 17 desmens. Naked part of cuticle not annulated. Somatic setae with typical desmoscolecid arrangement: nine pairs of subdorsal somatic setae on desmens 1, 3, 5, 7, 9, 11, 13, 16, 17; eight pairs of subventral setae on desmens 2, 4, 6, 8, 10, 12, 14, 15. Amphideal fovea ( Figure 2E View Figure 2 ) broadly rounded (4 mm long), largely covering head laterally. One pair of ocelli ( Figure 2D View Figure 2 ) dark yellowish, elliptical (10 mm 65 mm long), situated between desmens 3 and 4. Reproductive system not well developed, situated between desmens 9 and 11 ( Figure 2D View Figure 2 ). Vagina and vulva not observed in all specimens. Anal tube not protruding from body wall; anus at posterior border of desmen 15. Tail with two desmens ( Figure 2D View Figure 2 ). End ring 46 mm long, about 2.1 times longer than wide.

Diagnosis

Desmoscolex (Desmolorenzenia) coreensis sp. nov. is characterized by the following combination of characters: (1) presence of 17 desmens and typical desmoscolecid setal pattern (nine pairs of subdorsal somatic setae and eight pairs of subventral somatic setae); (2) globular head with truncated anterior end; (3) cephalic setae jointed distally, i.e. a finer tip socketed into broad, cylindrical basal part; (4) presence of a pair of ocelli situated between desmens 3 and 4; (5) somatic setae directly inserted on to cuticle; and (6) shape of end ring with a broad, cylindrical anterior part ranging up to insertion of posteriormost subdorsal somatic setae, and a ventrally bent terminal part tapering towards short naked spinneret.

For differential diagnosis, see Discussion.

Kingdom	Animalia
Phylum	Nematoda
Class	Adenophorea
Order	Desmoscolecida
Family	Desmoscolecidae