taxonID	type	description	language	source
E8363960FFBE8A5A78334BE3F51492B6.taxon	diagnosis	Diagnosis (emended from Decraemer 1983) Presence of desmen along entire body in the adult stage. The majority of the species (74) have seventeen main rings surrounding the annulated cuticle, nine species have eighteen main rings, 3 have less than seventeen main rings and 13 species have more than eighteen main rings. Rings rounded or quadricomoid. In the quadricomoid form, anterior rings slope backward, posterior rings slope forward, with no abrupt change in slope direction.	en	García-Cobo, Marta, González-Casarrubios, Alberto, Sánchez, Nuria (2025): Description of two new species of Desmoscolex Claparède, 1863 (Nematoda: Desmoscolecidae) from the Cassidaigne Canyon, Mediterranean Sea. European Journal of Taxonomy 1004: 211-236, DOI: 10.5852/ejt.2025.1004.2969, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2969/13373
E8363960FFBE8A5A78334BE3F51492B6.taxon	discussion	Remarks The present work raises the count of species of Desmoscoles (Desmoscolex) to 106 (see Table 1). Additionally, Desmoscolex noctuabundus Bussau, 1993 is proposed to be synonymized as Desmoscolex (Protricomoides) noctuabundus. According to Bussau (1993), the species exhibit incomplete main rings immediately after the cephalic region, followed by a bare cuticle, and ending with incomplete main rings extending from the anal region to the posterior end of the body. This pattern aligns with the description of the subgenus Desmoscolex (Protricomoides) Timm, 1970. It is worth noting that the use of the subgenus is optional, and both forms, with or without the subgenus, are valid as synonyms according to the ICZN code (1999). Table 1 provides an updated list of valid species of the genus Desmoscolex, along with their corresponding synonyms based on the original description of both the subgenus and the species. Species marked with * in the table are synonymized within the corresponding subgenus for the first time in this study.	en	García-Cobo, Marta, González-Casarrubios, Alberto, Sánchez, Nuria (2025): Description of two new species of Desmoscolex Claparède, 1863 (Nematoda: Desmoscolecidae) from the Cassidaigne Canyon, Mediterranean Sea. European Journal of Taxonomy 1004: 211-236, DOI: 10.5852/ejt.2025.1004.2969, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2969/13373
E8363960FFBE8A5A78274C6FF1749180.taxon	diagnosis	Diagnosis (emended from Decraemer & Rho 2014) Body cuticle with large main rings, separated by narrower or similarly wide interzones (one to five annules). Interzones smooth or with transverse row of fine spines or pores. Paired subdorsal and subventral somatic setae show various patterns. Often, red-brown pigment spots near the anterior intestine. Pharynx short, cylindrical, with junction opposite the posterior end of main ring two or the anterior end of main ring three in species with 17 – 18 rings. Intestine usually overlaps postrectally. Females didelphic-amphidelphic with outstretched ovaries, a spermatheca, and a vulva at posterior end of main ring 10 in 17 - ring species. Juveniles with fine annules, each with spines or warts, no desmen.	en	García-Cobo, Marta, González-Casarrubios, Alberto, Sánchez, Nuria (2025): Description of two new species of Desmoscolex Claparède, 1863 (Nematoda: Desmoscolecidae) from the Cassidaigne Canyon, Mediterranean Sea. European Journal of Taxonomy 1004: 211-236, DOI: 10.5852/ejt.2025.1004.2969, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2969/13373
E8363960FFB18A4D7BEF4E50F0EC94E2.taxon	description	urn: lsid: zoobank. org: act: 159 D 1 F 58 - 029 D- 40 A 1 - 8760 - 4 E 1376076352 Figs 1 – 4, Tables 1 – 3, 6	en	García-Cobo, Marta, González-Casarrubios, Alberto, Sánchez, Nuria (2025): Description of two new species of Desmoscolex Claparède, 1863 (Nematoda: Desmoscolecidae) from the Cassidaigne Canyon, Mediterranean Sea. European Journal of Taxonomy 1004: 211-236, DOI: 10.5852/ejt.2025.1004.2969, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2969/13373
E8363960FFB18A4D7BEF4E50F0EC94E2.taxon	diagnosis	Diagnosis Desmoscolex (Desmoscolex) nibelungus sp. nov. is mainly defined by: (1) presence of 17 main rings with typical desmoscolecid setae arrangement: nine pairs of subdorsal setae and eight pairs of subventral setae; (2) thick somatic setae, except for wiry terminal pair (3) slightly elongated subdorsal setae on the 16 th ring and more elongated subdorsal setae on the 17 th ring; (4) apparent absence of cephalic setae; (5) rounded cephalic region, with lip region not covered by concretion material; (6) strongly ventrally curved, beak-shape last main ring.	en	García-Cobo, Marta, González-Casarrubios, Alberto, Sánchez, Nuria (2025): Description of two new species of Desmoscolex Claparède, 1863 (Nematoda: Desmoscolecidae) from the Cassidaigne Canyon, Mediterranean Sea. European Journal of Taxonomy 1004: 211-236, DOI: 10.5852/ejt.2025.1004.2969, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2969/13373
E8363960FFB18A4D7BEF4E50F0EC94E2.taxon	etymology	Etymology The specific name ‘ nibelungus ’ refers to the cycle of four epic music dramas composed by Richard Wagner called The Ring of the Nibelung (‘ Der Ring des Nibelungen’ in German). Name chosen due to the presence of rings on the nematode’s body.	en	García-Cobo, Marta, González-Casarrubios, Alberto, Sánchez, Nuria (2025): Description of two new species of Desmoscolex Claparède, 1863 (Nematoda: Desmoscolecidae) from the Cassidaigne Canyon, Mediterranean Sea. European Journal of Taxonomy 1004: 211-236, DOI: 10.5852/ejt.2025.1004.2969, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2969/13373
E8363960FFB18A4D7BEF4E50F0EC94E2.taxon	materials_examined	Type material Holotype MEDITERRANEAN SEA • ♂, adult (mounted in glycerine); Cassidaigne Canyon, Station U 07; 43 ° 0 ′ 5.940 ″ N, 5 ° 19 ′ 12.510 ″ E; depth 1056 m; 11 Jan. 2022; CREOCEAN enterprise leg.; ZMB 12957; ZMB. Paratypes MEDITERRANEAN SEA • 2 ♂♂, adult (mounted in glycerine); same data as for holotype.; ZMB 12958 to 12959; ZMB • 1 ♀, adult (mounted in glycerine); same data as for preceding; ZMB 12961; ZMB • 1 ♀, adult (mounted in glycerine); Cassidaigne Canyon, Station U 06; 43 ° 2 ′ 20.352 ″ N, 5 ° 21 ′ 0.096 ″ E; depth 605 m; 11 Jan. 2022; CREOCEAN enterprise leg.; ZMB 12960; ZMB.	en	García-Cobo, Marta, González-Casarrubios, Alberto, Sánchez, Nuria (2025): Description of two new species of Desmoscolex Claparède, 1863 (Nematoda: Desmoscolecidae) from the Cassidaigne Canyon, Mediterranean Sea. European Journal of Taxonomy 1004: 211-236, DOI: 10.5852/ejt.2025.1004.2969, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2969/13373
E8363960FFB18A4D7BEF4E50F0EC94E2.taxon	description	Description See Table 2 for a summary of the most relevant measurements of the type material. Body short (249 – 310 µm), dorsally curved in holotype and one female paratype (M 1 and F 1), S-shaped in one male paratype (M 2), straight in one male paratype (M 3) and ventrally curved in one female paratype (F 2). Body slightly tapered towards anterior end (at level of cephalic region) and tail. Width almost uniform over rest of body. Body with 17 well-separated main rings covered by concretion material on annulated body cuticle. Main rings relatively rounded and separated by 3 – 4 cuticle annules (Figs 1 A, 2 A, 3 A, 4 A). Somatic setae inserted in peduncule and following typical desmoscolecid setal pattern of nine subdorsal and eight subventral pairs (see below). Both subdorsal and subventral setae thick, with cylindrical base and tapering towards distal end. Terminal setae of different shape, with thin and wiry appearance (Fig. 3 D). Subdorsal and subventral setae with similar shape and length (Table 2), except for slightly elongated subdorsal setae on 16 th main ring (16 µm) and more elongated subdorsal setae on 17 th ring (17 – 31 µm). Nine pairs of subdorsal somatic setae present on 1 st, 3 rd, 5 th, 7 th, 9 th, 11 th, 13 th, 16 th – 17 th main rings. One male specimen (M 2) has one subdorsal setae located on second ring instead of on third one. Eight pairs of subventral somatic setae located on 2 nd, 4 th, 6 th, 8 th, 10 th, 12 th, 14 th – 15 th main rings (Table 2). Cephalic region globular, moderately wider than long, slightly truncated anteriorly, with distinct lip region. Head cuticle completely covered with concretion material except beneath amphideal fovea. Amphideal fovea covering nearly completely lateral sides of cephalic region. Labial sensilla not detected. Cephalic setae apparently absent, not descirnable in optical microscopy (Figs 1 C, 3 C, 4 B). Short cheilostome at level of protruding lip region, leading to short (extending over 2 rings), nearly cylindrical pharynx without posterior pharyngeal bulb (Figs 1 B, 2 B, 3 B). In females, intestine with postrectal sac (Fig. 4 A) and anal tube protruding from 15 th main ring. One pair of pigment spots as orange, oval areas with well-defined border, present at level of 4 th – 5 th main rings (Figs 1 B, 2 B, 3 D, 4 A). Males monorchic with single testis outstretched and extending anteriorly up to level of 9 th desmos. Spicules (36 – 39 µm) slightly curved and cephalated. Gubernaculum absent. Cloacal tube broad, opening to exterior on 15 th main ring (Figs 1 B, 3 A). Both female paratypes with reproductive system inconspicuous. Even though hard to distinguish, reproductive system of female paratype (F 1) didelphic-amphidelphic, with anterior branch extending from base of 7 th main ring and posterior one to 15 th main ring. Vulva appearing at posterior end of 10 th main ring. Oocytes are observed between main rings 11 and 13 (Fig. 2) Tail with 2 main rings. Last main ring completely covered with concretion material, about 2,5 – 3 × as long as wide, and composed of wider and cylindrical anterior part with insertion of terminal pair of setae at its base (Figs 3 E, 4 D). Posterior part of last main ring strongly curved ventrally. Spinneret minute, not covered with concretion material.	en	García-Cobo, Marta, González-Casarrubios, Alberto, Sánchez, Nuria (2025): Description of two new species of Desmoscolex Claparède, 1863 (Nematoda: Desmoscolecidae) from the Cassidaigne Canyon, Mediterranean Sea. European Journal of Taxonomy 1004: 211-236, DOI: 10.5852/ejt.2025.1004.2969, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2969/13373
E8363960FFB18A4D7BEF4E50F0EC94E2.taxon	diagnosis	Differential diagnosis Based on similarities in the number of main rings, the somatic setal pattern, the globular cephalic region and circular amphids, D. (D.) nibelungus sp. nov. is grouped with other 14 species: D. (D.) australicus Decraemer, 1974; D. (D.) bathyalis Freudenhammer, 1975; D. (D.) borealis Kreis, 1963; D. (D.) coronatus Soetaert, 1989; D. (D.) galeatus Freudenhammer, 1975; D. (D.) gerlachi Timm, 1970; males of D. (D.) gladisetosus Timm, 1970; D. (D.) lapilliferus Freudenhammer, 1975; D. (D.) opacus Bussau, 1993; D. (D.) paraleptus Decraemer, 1975; D. (D.) perspicuus Freudenhammer, 1975; D. (D.) petalodes Lorenzen, 1972; D. (D.) rotundicephalus Jung, Kihm & Rho, 2024; and D. (D.) yongei Decraemer, 1974 (see Table 3). These species share as characteristics having 17 main rings along the body and same somatic setal pattern consisting of 9 pairs of subdorsal setae and 8 pairs of subventral ones. On the other hand, what distinguished D. (D.) nibelungus from the majority of the aforementioned group of species is the apparent lack of cephalic setae and its strongly ventrally curved, beak-shaped tail. The lack of cephalic setae is highly unusual; however, after careful examination of the type material under optical microscopy, no cephalic setae were observed. Desmoscolex (D.) rotundicephalus shares this peculiar characteristic with the species described here, as well as the uncovered lip region, the number of main rings and the somatic setae arrangement. Nevertheless, the somatic setae of D. (D.) rotundicephalus differ in length between subdorsal and subventral, though they share a similar shape. In contrast, the somatic setae of D. (D.) nibelungus are all of similar length, with the last pair exhibiting a wiry appearance. Additionally, the beak-shaped last main ring of D. (D.) nibelungus contrasts with the conical appearance of the last main ring in D. (D.) rotundicephalus. Apart from differing in the apparent lack of cephalic setae and the particular tail shape, D. (D.) australicus, D. (D.) gerlachi, D. (D.) paraleptus and D. (D.) yongei have subdorsal somatic setae with spatulated or lance-shaped tip, unlike D. (D.) nibelungus sp. nov. (Timm 1970; Decraemer 1974, 1975). The presence of a long and thin terminal main ring as well as the short cephalic setae with blunt tips (Freudenhammer 1975) are useful to differentiate D. (D.) bathyalis from the new species described herein. Regarding D. (D.) borealis, it differs from D. (D.) nibelungus sp. nov. in its fusiform body shape and the spinelike setae observed on the 15 th main ring (Kreis 1963). Both D. (D.) coronatus and D. (D.) nibelungus have a protuding lip region, not covered by concretion material. However, the subdorsal setae of D. (D.) coronatus are slightly longer than the subventral ones, it possesses short cephalic setae and a much shorter spicules in males (Soetaert 1989) (see Table 3). Desmoscolex (D.) galeatus has cephalic setae and an elongated pair of subdorsal setae on the 13 th and 16 th – 17 th rings (Freudenhammer 1975), unlike D. (D.) nibelungus sp. nov., whose pair of subdorsal setae on the 13 th main ring has average length (see Tables 2 and 3). Males of D. (D.) gladisetosus have wiry cephalic setae and a thin and long terminal main ring (Timm 1970), which differs from the aforementioned features that characterize the new species. Similarly, D. (D.) lapilliferus is notable for its somatic and cephalic setae with a long dark curved tip as well as a long and thin terminal main ring (Freudenhammer 1975), differing from D. (D.) nibelungus. The cauliflower-shaped cephalic setae of D. (D.) opacus distinguishes it from D. (D.) nibelungus (Bussau 1993). Unlike the species described in this study, D. (D.) perspicuus has short somatic setae, increasing in length towards the tail, as well as a long spinneret at its end (Freudenhammer 1975). Moreover, D. (D.) nibelungus apparently lacks cephalic setae, whereas D. (D.) petalodes possesses cephalic setae with flag-like tip (Lorenzen 1972).	en	García-Cobo, Marta, González-Casarrubios, Alberto, Sánchez, Nuria (2025): Description of two new species of Desmoscolex Claparède, 1863 (Nematoda: Desmoscolecidae) from the Cassidaigne Canyon, Mediterranean Sea. European Journal of Taxonomy 1004: 211-236, DOI: 10.5852/ejt.2025.1004.2969, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2969/13373
E8363960FFA98A4F78104D6CF5E79132.taxon	description	urn: lsid: zoobank. org: act: 69 FE 1 E 2 F- 4 C 1 B- 47 F 0 - 9988 - 3 AD 8 CACA 371 A Figs 5 – 6, Tables 1, 4 – 5	en	García-Cobo, Marta, González-Casarrubios, Alberto, Sánchez, Nuria (2025): Description of two new species of Desmoscolex Claparède, 1863 (Nematoda: Desmoscolecidae) from the Cassidaigne Canyon, Mediterranean Sea. European Journal of Taxonomy 1004: 211-236, DOI: 10.5852/ejt.2025.1004.2969, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2969/13373
E8363960FFA98A4F78104D6CF5E79132.taxon	diagnosis	Diagnosis The main diagnostic characteristics of Desmoscolex (Desmoscolex) valkyria sp. nov. include: (1) high number of main rings (22 – 24); (2) rounded cephalic region with prominent vesicular amphid; (3) thick cephalic setae; (4) reddish pigment globules along the interior of body; (5) penultimate main ring with both pairs of subdorsal and subventral setae; (6) wide, short and conical end ring with very long spinneret.	en	García-Cobo, Marta, González-Casarrubios, Alberto, Sánchez, Nuria (2025): Description of two new species of Desmoscolex Claparède, 1863 (Nematoda: Desmoscolecidae) from the Cassidaigne Canyon, Mediterranean Sea. European Journal of Taxonomy 1004: 211-236, DOI: 10.5852/ejt.2025.1004.2969, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2969/13373
E8363960FFA98A4F78104D6CF5E79132.taxon	etymology	Etymology The specific name ‘ valkyria ’ as noun in apposition refers to the female figures in Norse mythology who guide the souls of the dead to the Valhalla Hall of the god Odin and who star in the second opera of ‘ The Ring of the Nibelung’.	en	García-Cobo, Marta, González-Casarrubios, Alberto, Sánchez, Nuria (2025): Description of two new species of Desmoscolex Claparède, 1863 (Nematoda: Desmoscolecidae) from the Cassidaigne Canyon, Mediterranean Sea. European Journal of Taxonomy 1004: 211-236, DOI: 10.5852/ejt.2025.1004.2969, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2969/13373
E8363960FFA98A4F78104D6CF5E79132.taxon	materials_examined	Material examined Holotype MEDITERRANEAN SEA • ♂, adult (mounted in glycerine); Cassidaigne Canyon, Station U 13; 43 º 0 ′ 47.050 ″ N, 5 º 45 ′ 32.220 ″ E; depth 952 m; 27 Apr. 2022; CREOCEAN enterprise leg.; ZMB 12962; ZMB. Paratypes MEDITERRANEAN SEA • 1 ♂, adult (mounted in glycerine); Cassidaigne Canyon, Station U 08; 42 ° 57 ′ 25.770 ″ N, 5 ° 14 ′ 2.430 ″ E; depth 1530 m; 12 Jan. 2022; CREOCEAN enterprise leg.; ZMB 12963; ZMB • 1 ♂, adult (mounted in glycerine); Cassidaigne Canyon, Station U 09; 42 ° 51 ′ 32.040 ″ N, 5 ° 14 ′ 34.620 ″ E; depth 1968 m; 13 Jan. 2022; CREOCEAN enterprise leg.; ZMB 12964; ZMB.	en	García-Cobo, Marta, González-Casarrubios, Alberto, Sánchez, Nuria (2025): Description of two new species of Desmoscolex Claparède, 1863 (Nematoda: Desmoscolecidae) from the Cassidaigne Canyon, Mediterranean Sea. European Journal of Taxonomy 1004: 211-236, DOI: 10.5852/ejt.2025.1004.2969, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2969/13373
E8363960FFA98A4F78104D6CF5E79132.taxon	description	Description See Table 4 for a summary of the most relevant measurements of the type material. Body short (278 – 385 µm), ventrally coiled in holotype, M 1, and paratype, M 2, but straight in paratype, M 3. Body becomes tapered at level of cephalic region and at level of tail. Body wider at middle region. Body with 22 – 24 main rings. Nine pairs of subdorsal somatic setae and nine subventral somatic setae. Male holotype (23 main rings) with subdorsal setae on the 1 st, 3 rd, 5 th, 8 th, 11 th, 14 th, 18 th and 22 nd – 23 rd rings. On the other hand, subventral ones appear on the 2 nd, 4 th, 7 th, 10 th, 13 th, 16 th, 19 th and 21 st – 22 nd main rings. Arrangement of setae exhibits variability between specimens, starting from 11 th main ring for the subdorsal setae and from 13 th main ring for subventral setae (Table 4). Penultimate ring always with both dorsal and ventral pairs of setae (Fig. 5 A). Cephalic region globular, slightly wider than long. Cephalic region cuticle completely covered with concretion material. Vesicular amphid extending to first main ring. Labial sensilla not identified. Thick cephalic setae, shorter than cephalic region width, located laterally (Figs 5 C, 6 B, 6 C). Small mouth opening, leading to short (hardly extending over 2 rings), nearly cylindrical pharynx without posterior pharyngeal bulb (Figs 5 B, 6 A). Pigment spot located between 3 th and 5 th rings. Reddish pigment globules appear along internal structures, from end of pharynx until middle region of body (Figs 5 B, 6 A), apparently associated with intestine. Males monorchic with single testis outstretched and extending anteriorly up to level of 12 th main ring. Spicule almost straight and cephalated (Figs 5 B, 6 A). Gubernaculum parallel to spicule. Cloacal tube broad, opening outside always on antepenultimate main ring, occurring on 21 st main ring in holotype and paratype M 3, and on 22 nd ring in paratype M 2. No females found. Tail with two main rings. Last ring wide, short and conical with long and thin spinneret (12 – 13 µm) (Figs 5 A, 6 A, 6 D).	en	García-Cobo, Marta, González-Casarrubios, Alberto, Sánchez, Nuria (2025): Description of two new species of Desmoscolex Claparède, 1863 (Nematoda: Desmoscolecidae) from the Cassidaigne Canyon, Mediterranean Sea. European Journal of Taxonomy 1004: 211-236, DOI: 10.5852/ejt.2025.1004.2969, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2969/13373
E8363960FFA98A4F78104D6CF5E79132.taxon	diagnosis	Differential diagnosis Among the 12 described species of D. (Desmoscolex) that have more than 18 rings, 10 of them have more than 27 main rings. The most important features of Desmoscolex (D.) valkyria sp. nov. that characterize the species include: number of main rings (22 – 24), two pairs of somatic setae from the penultimate ring and elongated spinneret (Table 5). Female specimens of D. (D.) aquaedulcis Stammer, 1935 have 22 rings, but differ in the number of subdorsal somatic setae: two pairs in D. (D.) aquaedulcis and nine pairs in D. (D.) valkyria. Females of D. (D.) aquaedulcis also have a long end-ring with a short and pointy spinneret, unlike the short and conical tail of D. (D.) valkyria with a long spinneret. Males of D. (D.) californicus Timm, 1970 have between 22 and 23 main rings, a vesicular amphid, a short and conical end-ring and red pigment globules. Nevertheless, D. (D.) californicus lacks two pairs of setae on the penultimate ring, and a long spinneret but has a triangular cephalic region instead of the globular cephalic region of D. (D.) valkyria.	en	García-Cobo, Marta, González-Casarrubios, Alberto, Sánchez, Nuria (2025): Description of two new species of Desmoscolex Claparède, 1863 (Nematoda: Desmoscolecidae) from the Cassidaigne Canyon, Mediterranean Sea. European Journal of Taxonomy 1004: 211-236, DOI: 10.5852/ejt.2025.1004.2969, URL: https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2969/13373
