Sphaerephesia artabrensis (Moreira & Parapar, 2007) Moreira & Parapar, 2007

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 : 39-42

Sphaerephesia artabrensis (Moreira & Parapar, 2007) comb. n. Figs 5I, 14, 15A, B

Sphaerodoropsis artabrensis Moreira & Parapar, 2007: 374-377, figs 1-2, 3A; Moreira et al. 2011: 30.

Type locality.

Ártabro Gulf, NW Iberian Peninsula, 43°40.192'N, 8°43.760'W, 209 m.

Material examined.

Paratypes: (3 specs) SMF 16881/3, Golfo Ártabro, NW Spain, DIVA-Artabria I-02, sample EBS-250, 43°41.11'N, 08°44.23'W, 257 m, 14 Sep 2002.Additional material (119 specs): NW Spain: MNCN 16.01/13270 (40 specs), Golfo Ártabro, 43°40.25'N, 08°43.75'W, 197-207 m, 12 Sep 2003. MNCN 16.01/18461 (79 specs), 42°30.39'N, 09°19.52'W, 147 m, 17 Sep 2004.

Diagnosis.

Body short and ellipsoid, up to 1.75 mm long. Palps and antennae smooth, lacking spurs or basal papillae. Median antenna shorter than palps and lateral antennae. Antenniform papillae present. Four longitudinal rows of macrotubercles in a single transverse row per segment. Macrotubercles sessile, small, spherical to pear shaped. Additional small spherical papillae on dorsum (arranged in four irregular transverse rows with ca. 20 papillae per segment) and ventral surfaces. Parapodia coni cal, with 3-4 sub-equal papillae (1-2 ventral, one anterior, one dorsal). Acicular lobe from chaetiger 2. Ventral cirri digitiform as long as acicular lobe tip, or shorter. Compound chaetae with long blades (8-20 times as long as wide), unidentate and with serrated edge. Some live and fixed specimens have pigmented orange to brown macrotubercles. Some females with oocytes, without visible nucleus; genital pores observed between chaetiger 7 and 8.

Remarks.

Sphaerodoropsis artabrensis was described based on the unique combination of the following morphological features: spherical to pear-shaped macrotubercles arranged in four longitudinal rows, 3-4 sub-equal parapodial papillae, chaetae with long blades (8-20 times as long as wide), showing gradation within each fascicle. The original description of this species is complete and re-examination of Iberian material, even under the SEM, did not provide additional information about morphological features, but allowed to verify some of the attributes. Palps and antennae are smooth, lacking spurs or basal papillae (Fig. 14B, C); median antenna shortest (Fig. 14B). Antenniform papillae present (Fig. 14B). Small spherical papillae over dorsum forming four irregular transverse rows with about 20 papillae per segment in addition to the four macrotubercles (Fig. 15A), similar number and arrangement on ventrum (Fig. 15B). Parapodia conical, with 3-4 sub-equal papillae (1-2 ventral, one anterior, one dorsal) (Figs 5I, 14E, F, H). Acicular lobe from chaetiger 1-2. Ventral cirri digitiform as long as acicular lobe tip, or shorter (Fig. 14F). Compound chaetae with long blades (8-20 times as long as wide), unidentate and with serrated edge (Fig. 14F, H–J). It is the first time that genital pores are reported in the species. These have only been observed in females, as a flat, porous area, between parapodia of chaetiger 7 and 8 (Fig. 14G).

This species is herein transferred to the genus Sphaerephesia due to the number and arrangement of dorsal macrotubercles in four longitudinal rows.

Specimens of S. artabrensis comb. n., resemble those assigned herein as Sphaerephesia philippi comb. n. from Nordic waters but they present subtle but consistent differences. Northern specimens are generally larger (Iberian specimens are up to 1.75 mm long and northern ones almost double in size), and bear a few more papillae in the prostomium, dorsum and parapodia (6-7 instead of the 3-4 in Iberian specimens). Specimens from northern localities present an acicular lobe from segment 1, instead of segment 2. Ventral cirri do not surpass the acicular lobe. It would be most interesting to confirm that these differences can be attributed to different lineages and not to the intraspecific range of variation of a species with a broad distribution from Spain to the Kara Sea. However, we have been unable to find specimens collected all along the coasts, and instead only in NW Spain and then from Skagerrak to the North. Moreover, extraction and amplification of DNA in specimens collected in the NW of Spain was unsuccessful and were therefore not included in analyses.

Distribution.

NW Iberian Peninsula ( Moreira and Parapar 2007, Moreira et al. 2011).

Habitat.

Continental slope, in sandy-muddy sediments, 200-2200 m ( Moreira and Parapar 2007, Moreira et al. 2011).