Clavodorum kristiani ( Hartmann-Schroeder , 1993), comb. n.

Capa, Maria, Nygren, Arne, Parapar, Julio, Bakken, Torkild, Meissner, Karin & Moreira, Juan, 2019, Systematic re-structure and new species of Sphaerodoridae (Annelida) after morphological revision and molecular phylogenetic analyses of the North East Atlantic fauna, ZooKeys 845, pp. 1-97 : 16-21

Clavodorum kristiani ( Hartmann-Schroeder, 1993), comb. n. nom. n. Figs 4C, D, 5B, 6, 7, 8A

Sphaerodoridium fauchaldi Hartmann-Schröder, 1993: 123-125, figs 1-9; Hartmann-Schröder 1996: 234-235, fig. 104; Aguirrezabalaga and Cebeiro 2005: 16-19, figs 5, 6; Moreira and Parapar 2007: 377-378, fig. 3 B–E; Moreira et al. 2011: 26, fig. 3; Moreira 2012: 28-29, fig. 6.

Type locality.

North Sea, 58°16.98'N, 0°58.31'W, 172 m.

Material examined.

Holotype: ZMH P21082, North Sea, (N. Scotland) 58°16.98'N, 0°58.31'W, 172 m.

Additional material.

(140 specs) Norwegian Sea: NTNU-VM 74198 (3 specs in SEM stub), Sandsfjord, 62°12.3'N, 5°26.7'E, 85 m, 18 Oct 1987; ZMBN 127253 (1 spec.), Sandsfjord, 62°12.3'N, 5°26.7'E, 85 m, 18 Oct 1987; ZMBN 127256 (1 spec. for DNA sequencing, SPH274), Møre og Romsdal, 63°18.81'N, 6°39.24'E, 226 m, 26 Sep 2012; ZMBN 127257 (1 spec. for DNA sequencing, SPH275), Norwegian Sea, Møre og Romsdal, 63°18.81'N, 6°39.24'E, 226 m, 26 Sep 2012; NTNU VM 68172 (1 spec. used for DNA sequencing, SPH276), Ytre Mørebanken, 004°29.74'N, 62°36.86'E, 203 m, 03. Oct. 2012; ZMBN 103139 (1 spec. used for DNA sequencing, SPH075), 62°36.858'N, 4°29.742'E, Møre og Romsdal, 203 m, 3 Oct. 2012; NTNU VM 65127 (5 spec.), Halsafjord, Ytterfjorden, 63°10.17'N, 7°43.9'E, 150 m, 25 May 1884; ZMBN 127254 (1 spec. used for DNA sequencing, SPH314), Bergen, 60°16.181'N, 5°11.865'E, 120 m, 25 Jul 2014; ZMBN 127255 (1 spec. used for DNA sequencing, SPH315), Bergen, 60°16.181'N, 5°11.865'E, 120 m, 25 Jul 2014; ZMBN 125433 (1 spec. used for DNA sequencing, SPH312), Rogaland, Kvitsøy, 59°1.791'N, 5°26.929'E, 58 m, 10 Jun 2014; ZMBN 127258 (1 spec. used for DNA sequencing, SPH313 photographed alive, Fig. 8A), Rogaland, Karmøysundet, 59°17.273'N, 5°19.504'E, 74 m, 08 Jun 2014; ZMBN 127259 (1 spec. used for DNA sequencing, SPH326), Rogaland, Karmøysundet, 59°17.273'N, 5°19.504'E, 74 m, 08 Jun 2014. Continental shelf, Galicia, NW Spain: MNCN 16.01/18456 (27 specs), 43°35.45'N, 08°34.43'W, 152 m, 8 Sep 2002; MNCN 16.01/18457 (52 specs), 43°34.13'N, 8°36.56'W, 152 m, 14 Sep 2003; MNCN 16.01/18458 (42 specs), 42°30.39'N, 09°19.52'W, 147 m, 17 Sep 2004; MNCN 16.01/18459 (41 specs), 42°15.82'N, 09°22.68'W, 260 m, 23 Oct 2009. Morocco, ZMBN 103140 (1 spec. used for DNA sequencing, SPH025), Atlantic Ocean, 28°0.04836'N, 13°16.32'W, 100 m, 4 Dec 2011.

Diagnosis.

Body ellipsoid. Median antenna shorter than lateral antennae; lateral antennae and palps with 1-2 basal papillae each; antenniform papillae absent. Dorsal macrotubercles stalked, without terminal papilla, arranged in five longitudinal rows in first three chaetigers, and six longitudinal rows in following chaetigers; stalk and tubercle of similar length. Additional epithelial papillae on dorsum absent. Six to eight longitudinal rows of smaller tubercles with short stalk on ventrum; two tubercles near each parapodium slightly larger than others. Parapodia with long, oval acicular lobe from chaetiger 4; ventral cirri large, reaching or surpassing length of acicular lobe. Three parapodial papillae: one on antero-lateral surface from chaetiger 2, one ventral from chaetiger 3-4 and one terminal digitiform papilla from chaetiger 1, behind chaetae.

Re-description of holotype.

Measurements and general morphology. Body ellipsoid, measuring 1.0 mm long, 0.4 m wide, with nine segments; with rounded anterior and posterior ends, with slightly flat ventrum. Segmentation inconspicuous and pigmentation absent in preserved specimen (Fig. 8A).

Head. Head fused to first chaetiger, with elongated and digitiform prostomial appendages, reaching the end of peristomium (Figs 6A, 7C). Lateral antennae slightly longer than palps, with 1-2 digitiform, shorter and thinner basal papillae each. Me dian antenna shorter than lateral, lacking spurs or basal papillae. Five prostomial papillae between lateral antennae and palps (Figs 6A, B, 7C). Tentacular cirri approx. half of length of prostomial appendages and thinner, with a basal papilla each (Figs 6A, C, 7C). An irregular transverse row of ca. 6-10 elongated papillae behind median antenna and tentacular cirri. Up to eight elongated papillae surrounding mouth (Fig. 6B, C).

Tubercles. Body with stalked dorsal macrotubercles distributed in five longitudinal rows on three anterior segments and six rows in following segments; one transverse row per segment (Figs 4C, 6A, 8A). Stalk shorter or as long as macrotubercle, the later oval, smooth, and lacking terminal papilla (Fig. 7D). Ventral surface with 6-8 longi tudinal rows of oval to rounded smaller tubercles with short stalk (Figs 4D, 6E); one (sometimes two) tubercles in between parapodia areas and six in parapodial areas; two tubercles closer to each parapodium slightly larger than others. Dorsum and lateral surfaces lacking papillae (Fig. 6C).

Parapodia. Parapodia cylindrical, longer than wide, increasing in length in mid-body. Acicular lobe long, oval from chaetiger 4 (Fig. 6C, E). Ventral cirri digitiform to conical, slightly tapering in width distally; as long or slightly shorter than parapodia in chaetigers 1-3; in following chaetigers at least reaching distal end of acicular lobe (Fig. 7E, G). Parapodial papillae numbering usually up to three: one terminal digitiform papilla ("postchaetal lobe") present from chaetiger 1 (sometimes two papillae in a few mid-body chaetigers); one large spherical to ellipsoid papilla from chaetiger 3-4, on proximal half of ventral surface of parapodia; one digitiform papilla from chaetiger 2, centred on anterior surface of parapodia (Figs 5B, 6E, 7 E–G). One straight acicula supporting each parapodium.

Chaetae. All chaetae compound, ca. 7-8 in first segment to 12-13 in middle chaetigers; with long, straight, unidentate and finally serrated blades (Fig. 7 H–J). Blades similar in length within chaetigers, slightly shorter in mid-body to posterior chaetigers; ca. 6-7 times longer than maximum width (Fig. 7I, J).

Pygidium. Paired anal cirri similar to dorsal macrotubercles and ventral digitiform anal papilla similar in length to lateral cirri (Figs 6D, 7A).

Internal structures. Muscular pharynx between segments 2 and 4. Eyes or nuchal organs not seen in holotype.

Reproductive features. Gametes or sexual structures not observed in holotype.

Variation.

Additional material measuring 1.0-3.5 mm in length and 0.33-0.37 mm wide; with 10-20 (usually 17-18) chaetigers. Live specimens unpigmented, with dorsum covered with small sediment particles, except for dorsal macrotubercles (Fig. 8A). Two oval eyes at level of median antenna or chaetiger 1-2, in some specimens (Fig. 8A). Stalk of dorsal macrotubercle is as long as the tubercle but in many specimens is contracted and therefore seems much shorter (e.g., Fig. 6C vs 6D). Usually, up to seven ventral stalked papillae in mid-body chaetigers but first two and last 2-3 chaetigers may show six (rarely five) papillae. Some specimens show the inter-parapodial tubercle displaced to parapodial areas. Ventral parapodial papilla usually appears in chaetiger 3-4 but in one specimen first appears in chaetiger 7. Otherwise, postchaetal papilla, lateral papilla, and acicular lobe appear constantly in chaetigers 1, 2, and 4 respectively. Muscular pharynx through segments 3-5. Genital openings distinguished in larger females and males (> 2 mm long) as swallowing of the tissue near the base of parapodia between chaetigers 8 and 9 (Figs 4D, 6E).

Etymology.

This species, originally described as Sphaerodoridium fauchaldi was dedicated to our colleague and prolific annelid systematist Kristian Fauchald ( Hartmann-Schröder, 1993). The new name given to it, after the genus Sphaerodorum is synonymised with Clavodorum and therefore the species is homonym to the previously described Clavodorum fauchaldi Desbruyères, 1980, aims to maintain tribute to Kristian, and therefore kristiani is proposed.

Remarks.

The present diagnosis is based in the original description of Sphaerodoridium fauchaldi by Hartmann-Schröder (1993), additional observations ( Aguirrezabalaga and Ceberio 2005, Moreira and Parapar 2007) and examination of the holotype, and several specimens from NW Spain and Nordic Seas. This species was described based on one small specimen (1.0 mm long, Fig. 2D, E); several minor differences were reported in material from the Bay of Biscay and NW Spain ( Aguirrezabalaga and Ceberio 2005, Moreira and Parapar 2007) but these can be due to the size and state of maturity of the holotype. For instance, Hartmann-Schröder (1993) did not mention the presence of a ventral parapodial papilla, that is present in specimens reported by Aguirrezabalaga and Ceberio (2005) and Moreira and Parapar (2007) and in those examined in this study; however, this papilla could have been mistaken with a ventral small tubercle by Hartmann-Schröder (1993), and in fact one ventral papilla seems half-drawn in the original description ( Hartmann-Schröder 1993: Fig. 8). Otherwise, this species is well characterized and can easily be distinguished from other Clavodorum - Sphaerodoridium species from the NE Atlantic, based on the number and arrangement of small ventral tubercles and lack of additional epithelial papillae.

Distribution.

We are reporting the species for the first time for the Norwegian Sea and Morocco. Previous records of the species include: North Sea ( Hartmann-Schröder 1993); Bay of Biscay ( Aguirrezabalaga and Ceberio 2005); NW Iberian Peninsula ( Moreira and Parapar 2007, Moreira et al. 2011).

Habitat.

Continental shelf, sandy sediments (70-1000 m) ( Moreira et al. 2011, and present study).