Sphaerephesia martinae ( Desbruyeres , 1980) 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 : 45-48

Sphaerephesia martinae ( Desbruyeres, 1980) comb. n. Figs 5M, 15G, H, 17

Type locality.

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

Material examined.

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

Additional material.

(18 specs) Argentinian Basin: SMFDZMB HH 21466 (2 specs, 1 spec. used for DNA sequencing, SPH021), 036°00.61'S, 049°01.54'W, 4607 m, 16 Jul 2009; Iceland: SMF 25283 (1 spec.), South Iceland, Iceland Basin, 60°02.73'N, 021°28.06'W, 2749 m, 28 Aug 2011; SMF 25286 (8 specs, 2 on SEM stub), South Iceland, 60°02.73'N, 4 021°28.06'W, 2749 m, 28 Aug 2011; SMF 23911 (1 spec., DNA SPH063.), South Iceland, 60°02.73'N, 021°28.06'W, 2749 m, 28 Aug 2011; SMF 23910 (1 spec. used for DNA sequencing, SPH048), Iceland, 036°00.61'S, 049°01.54'W, 2749 m, 7 Sep 2011; SMFDZMB HH 31236 (1 spec. on SEM stub), South Iceland, Iceland Basin, 60°21.48'N, 018°08.24'W, 2567 m, 30 Aug 2011; SMF 25285 (2 specs) South Iceland, Iceland Basin, 62°33.10'N, 020°23.71'W, 1384 m, 2 Sep 2011. Barents Sea: NTNU-VM 68189 (1 spec. used for DNA sequencing, SPH 293), Finnmark, 72°18.588'N, 32°20.478'E, 313 m, 4 Aug 2013.

Diagnosis.

Body ellipsoid, with convex dorsum and slightly flattened dorsoventrally, up to 3 mm long. Head appendages smooth, without spurs, median antenna slightly shorter than other appendages. Antenniform papillae shorter than lateral antennae. Dorsum with four longitudinal rows of large, hemispherical sessile macrotubercles in a single transverse row per segment, from segment 2. Additional papillae on dorsum arranged in four irregular transverse rows. Ventrum with three transverse rows of papillae similar in shape and size to dorsal. Parapodia short and conical, with 2-3 small, rounded papillae: one on each anterior and posterior surfaces, one in the ventrum of some parapodia. Acicular lobe from segment 1. Ventral cirri digitiform reaching acicular lobe tip. Approx. 7-10 compound chaetae with medium length blades (ca. 5-6 times as long as wide); unidentate and with fine spinulation along its margin. Several paratypes were described as possessing orange macrotubercles ( Desbruyères, 1980). One pair of genital structures between the base of parapodia 6 and 7.

Re-description of holotype.

Measurements and general morphology. Holotype 15 chaetigers, 2.9 mm long, 0.5 mm maximum width. Body almost cylindrical, slightly more rounded anteriorly and tapering posteriorly (Fig. 17A). Segmentation not distinct, pigmentation absent in preserved material examined.

Head. Prostomium fused to peristomium (Fig. 17B). Palps and lateral antennae digitiform, slightly wider at base, similar in shape and size. Median antenna digitiform, shorter than other appendages. Antenniform papillae present, slightly larger than other head papillae. Head with more than ten hemispherical papillae. Tentacular cirri digitiform, half of the length of lateral antennae (Fig. 17B).

Tubercles. Dorsal macrotubercles, hemispherical, wide and low, sessile and smooth, arranged in four rows, occupying most of dorsum; one transverse row per segment, except for the first segment where only two are present (Figs 15G, 17A). Dorsal papillae low and rounded, distributed in four transverse rows approximately, more numerous and conspicuous in anterior segments (Fig. 17C). Ventral papillae similar in shape and size to dorsal, arranged in three transverse rows per segment (Figs 15H, 17D).

Parapodia. Parapodia short and wrinkled, twice as long as wide, conical in shape. Ventral cirri conical, shorter than the width of parapodia. Acicular lobe, shorter than ventral cirri, present from first chaetiger (Fig. 17A). Two or three small, rounded papillae: one on each anterior and posterior surfaces, one in the ventrum of some parapodia (Figs 5M, 17 E–G).

Chaetae. Seven to ten chaetae per parapodia. All chaetae compound medium in length (5-6 times as long as wide), similar within and between parapodia, unidentate and with fine serrated edge (Fig. 17E, G, I, J).

Pygidium. Two globular cirri, similar to dorsal macrotubercles and two ventral small cirri (perhaps the ventral cirri of last segment). Median papilla not observed.

Internal features. Pigmented nuchal organs or eyes not seen. Pharynx not observed.

Reproductive features. Sexual structures, genital openings or gametes not observed in holotype, paratypes or additional material.

Variation.

Studied specimens measured 2-3 mm long. In all specimens macrotubercles are hemispherical. Some variation regarding the number of parapodial papillae has been observed. Most specimens present one hemispherical papilla on the anterior surface and a similar one on the posterior side, but a smaller ventral papilla may be also present. One pair of genital openings between the base of parapodia 6 and 7 in one specimen (SMFDZMB HH 31236, Fig. 17H).

Remarks.

The shape of macrotubercles is remarkable: hemispherical, low and wide, with a rounded and smooth surface and no papillae. This feature, together with the pres ence of almost inconspicuous additional epithelial papillae is one of its main diagnostic features ( Desbruyères, 1980), that distinguishes this species from other congeners.

The invaginations described behind the lateral antennae in the original description, are here considered as the openings of the nuchal organs. The parapodial papillae were not described in the original description, and at least one hemispherical papilla was observed in the anterior parapodial surface, from chaetiger 6 in the holotype, and additional material present up to three parapodial papillae. Holotype is full of gametes but sexual structures or genital openings were not detected. Sexual structures are described in this species for the first time in additional material from Iceland.

Distribution.

The species is here newly reported for Iceland and the Barents Sea. It had previously been reported in Bay of Biscay ( Desbruyères, 1980).

Habitat.

Sediments from 30 to 2750 m ( Desbruyères, 1980, present study).