Sphaerephesia stellifer (Aguirrezabalaga & Ceberio, 2005) Aguirrezabalaga & Ceberio, 2005

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 : 59

Sphaerephesia stellifer (Aguirrezabalaga & Ceberio, 2005) comb. n. Fig. 5R, 15Q, R

Sphaerodoropsis stellifer Aguirrezabalaga & Ceberio, 2005: 13-16, Figs 3-4.

Type locality.

Capbreton Canyon, Bay of Biscay, 43°42.01'N, 2°18.52'W, 990 m.

Material examined.

Holotype: MNCN 16.01/9051, Bay of Biscay, Capbreton Canyon, 43°42.01'N, 2°18.52'W, 990 m; Paratype: MNHN, apparently lost.

Diagnosis.

Body ellipsoid, flattened dorsoventrally, up to 3.2 mm long. Head appendages digitiform, lacking spurs. Median antenna shorter than palps and lateral antennae. Antenniform papillae present. Dorsum with four longitudinal rows of macrotubercles, in a single transverse row per segment, from segment 2. Macrotubercles sessile pear-shaped. Additional small spherical papillae on dorsum, arranged in 3-4 transverse rows per segment, each with ca. ten papillae. Ventrum with papillae, in 3-4 transverse rows per segment. Parapodia conical, with 7-10 sub-equal papillae uniformly distributed. Ventral cirri digitiform not surpassing acicular lobe tip. Approximately 6-12 compound chaetae with medium length blades (near six times their width), showing small gradation within fascicles; unidentate and subtle spinulation along its cutting margin.

Variation.

According to the original description, the range of variation of material examined is 18-20 chaetigers, 1.7-3.1 mm long and 0.6-0.8 mm wide.

Remarks.

Sphaerephesia stellifer comb. n. was described as a new species due to the star-shaped epithelial papillae, instead of spherical, oval of hemispherical, typical from other sphaerodorids. Revision of the holotype did not ensure this particular condition any longer, and instead it has the characteristic pear-shaped dorsal macrotubercles, resembling other Sphaerephesia species. The original drawings even include a close up of a macrotubercle with a small terminal papilla. Therefore, we suspect the shape described by Aguirrezabalaga and Ceberio (2005) as 'macrotubercles with funnel-like distal invaginations’ can be attributable to temporary collapse of the tubercles and it has now reverted to the typical pear-shaped tubercles. Collapsed epithelial tubercles has been observed in specimens of different species, indicating it may be related to particular fixation procedures and making it a not reliable diagnostic feature.

A combination of features may allow distinguishing S. stellifer comb. n. from other NEA Sphaerephesia . These include the ellipsoid body shape, presence of pear-shaped macrotubercles, 3-4 transverse rows of additional papillae over dorsum and ventrum, conical parapodia with ca. ten papillae, and 6-12 chaetae, near six times as long as wide. Nevertheless, Sphaerephesia laureci comb. n. is a similar species with a more elongated body and also longer parapodia ( Desbruyères, 1980); further studies should conclude if these features are enough to separate representatives of these species, or if S. stellifer comb. n. is in fact a junior synonym of S. laureci comb. n.

Distribution.

Capbreton Canyon, Bay of Biscay ( Aguirezzabalaga and Ceberio 2005).

Habitat.

Soft bottoms at depths of between 990-1040 m.