Clavodorum fauchaldi Desbruyeres , 1980

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 : 11-15

Clavodorum fauchaldi Desbruyeres, 1980 Figs 2, 3, 4A, B, 5A

Clavodorum fauchaldi Desbruyères, 1980: 110-112, fig. 1.

Type locality.

Banc Le Danois, Bay of Biscay, 44°05.2'N, 4°19.4'W, 1913 m.

Material examined.

Holotype: MNHN POLY TYPE 1279, Bay of Biscay, Banc Le Danois, 44°05.2'N, 4°19.4'W, 1913 m, 1972.

Additional material.

(141 specs) Iceland: IINH 38781 (55 specs,5 on SEM stub), 62°20.50'N, 16°59.30'W, 2074 m, 29 Aug 1995; IINH 38782 (25 specs -6 on SEM stub-), 61°50.22'N, 16°52.86'W, 2270 m, 29 Aug 1995; IINH 38783 (5 specs), 65°15.61'N, 28°50.15'W, 1300 m, 25 Aug 1996; IINH 38784 (2 specs), 60°02.03'N, 22°27.17'W, 2537 m, 29 July 2000; IINH 38785 (3 specs), 62°24.80'N, 19°48.60'W, 1780 m, 13 Sep 2001; IINH 38786 (1 spec.), 62°48.00'N, 16°14.80'W, 1813 m, 16 Sep 2001; IINH 38787 (30 specs), 62°02.40'N, 19°38.71'W, 1678 m, 3 Sep 2002; IINH 38788 (18 specs), 62°31.14'N, 17°09.87'W, 1940 m, 7 Sep 2002; IINH 38789 (1 spec.), 62°47.19'N, 17°20.37'W, 1662 m, 8 Sep 2002; IINH 38790 (1 spec.), 63°30.22'N, 29°38.40'W, 2233 m, 5 Sep 2003; ZMBN 127252 (1 spec.), South Iceland, 61°38.2'N16°27.7'W, 2355 m, 5 Jun 1983.

Diagnosis.

Body ellipsoid. Median antenna similar in length to lateral antennae; lateral antennae with three or four basal papillae each; antenniform papillae absent; palps with 2-3 basal papillae each. Dorsal macrotubercles stalked, without terminal papilla, arranged in five longitudinal rows in first 2-3 and last chaetigers, and six longitudinal rows in middle chaetigers; stalk and tubercle of similar length. Additional hemispherical papillae (ca. 10-12) distributed over dorsum in two irregular transverse rows, following a zig-zag pattern. Two rows of stalked smaller tubercles along ventrum, with two tubercles near each parapodium. Parapodia with acicular lobe from chaetiger 1, and large ventral cirri, surpassing length of acicular lobe. One ventral papilla from chaetiger 2-4; and one terminal postchaetal papilla from chaetiger 7-10.

Re-description of holotype.

Measurements and general morphology. Holotype oval in shape, measuring 2.7 mm long, 0.4 mm wide for 24 chaetigers.

Head. Head fused to first chaetiger, with elongated and digitiform prostomial appendages, reaching the end of head (Figs 2 A–C, 3A). Palps and lateral antennae similar in length, with 2-4 digitiform, shorter and slightly thinner basal papillae. Median antenna, similar in length to lateral, lacking spurs or basal papillae (Fig. 2B). Tentacular cirri ca. half of the length of prostomial appendages and thinned. Some elongated papillae distributed randomly on posterior part of head (Fig. 3B). Proboscis retracted in holotype and muscular pharynx through segments 3-6.

Tubercles. Body with stalked dorsal macrotubercles distributed in five longitudinal rows, on three anterior and two posterior segments and six rows in segments in between, although some detached in holotype; one transverse row per segment (Figs 3A, D, E, 4A). Stalk ca. the length of the macrotubercle, the latter oval, smooth, lacking terminal papilla (Figs 2A, D, 3D, E). Dorsal papillae in two irregular transverse rows, 4-6 papillae each per segment, rounded in shape (Fig. 4A). Ventral surface with two longitudinal rows of oval and stalked tubercles, arranged in two transverse rows per segment; anterior row with smaller tubercles than those of posterior row within each segment (Figs 2D, 3 F–I, 4B).

Parapodia. Parapodia cylindrical, longer than wide, similar in length along body, with almost similar in length ventral cirri, digitiform or slightly tapering in width dis tally, well surpassing length of acicular lobe (Figs 2D, 3 G–J). One large and rounded parapodial papilla from segment 2, located on the distal half of the antero-ventral surface of parapodia. One terminal papilla present from chaetiger 8, digitiform (Fig. 5A), and increasing its size to posterior chaetigers. One straight acicula supporting each parapodia, curved in first chaetigers.

Chaetae. All chaetae compound, ca. six in first segment to eight in middle chaetigers; with long, straight, unidentate and finally serrated blades. Blades similar in length between and within chaetigers, ca. ten times longer than maximum blade width (Fig. 3 K–M).

Pygidium. Paired anal cirri similar to dorsal macrotubercles and ventral digitiform anal papilla similar in length to lateral cirri.

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

Variation.

Intraspecific variation was assessed by examining a number of samples collected during the BIOICE project, in Iceland. Largest specimen examined 3.75 mm long, 1 mm wide and 28 chaetigers. Most Icelandic specimens measuring ca. 2 mm in length, 0.65 mm in width with 18-24 chaetigers. Median antenna usually as long as lateral antennae, depending on the state of contraction of specimens. Tentacular cirri shorter than prostomial appendages and provided each with two short papillae near the base. One dorsal transverse row of eight longer papillae (clavate or digitiform) behind median antenna and running at level of tentacular cirri; several digitiform papillae surrounding the mouth at each side (usually including one bifid and sometimes one trifid). Muscular pharynx extending over three chaetigers (5-7). In some elongated specimens stalk seems slightly longer than macrotubercle. Postchaetal papilla present from chaetiger 7 to last chaetiger. Parapodial antero-ventral papilla present from chaetigers 2-4, becoming more lateral in chaetigers 8-10; rounded to elongated in shape. Acicula is straight and chaetae blades show some gradation in length, being ventral ones slightly shorter in middle and posterior chaetigers. Several females with oocytes and males observed; both sexes show genital openings near the base of parapodia between chaetigers 8 and 9 (Fig. 4B).

Remarks.

The original description indicates that at least two specimens were found (holotype and another used for SEM) but only the holotype has been deposited in a museum collection (MNHN). All the specimens examined from Iceland bear three basal papillae on lateral antennae, variation that has been added into the diagnoses, at least one or two emerge directly from the base of antennae and the rest probably from the surroundings of the base. This species was described as new due to the uniqueness of its parapodia, with postchaetal lobe absent on anterior segments. However, we consider here that the postchaetal lobe is a postchaetal papilla. Furthermore, both females and males from Iceland samples show a pair of ventral genital openings (Fig. 2D); these may be interpreted as sexual structures and therefore this is the first mention for the genus of such features.

Distribution.

Iceland (present study), Bay of Biscay ( Desbruyères 1980).

Habitat.

Bathyal soft bottoms (1300-2537 m) ( Desbruyères 1980; this study).