Sabellaria Lamarck, 1812

Santos, André Souza Dos, Brasil, Ana Claudia Dos Santos & Christoffersen, Martin Lindsey, 2014, Sabellaria and Lygdamis (Polychaeta: Sabellariidae) from reefs off northeastern Brazil including a new species of Sabellaria, Zootaxa 3881 (2), pp. 125-144 : 130-131

Genus Sabellaria Lamarck, 1812

Sabellaria Kirtley, 1994: 45 –46; Nishi et al. 2010: 7 .

Type species. Sabella alveolata Linnaeus, 1767 , by monotypy, collected in France.

Emended diagnosis. Operculum completely divided into two symmetrical lobes, inner paleae in three symmetrical, semicircular rows (with mid and inner paleae), and three parathoracic segments (Santos et al. 2011).

Emended description. Operculum length similar to maximum width, completely divided into two symmetrical lobes; distal disc flat, perpendicular to longitudinal axis. Numerous conical opercular papillae around operculum. Outer paleae numerous, in semicircles; geniculate, with flat blades, lateral edge smooth, and distal margin smooth or denticulate, sometimes with a midline plume. Inner opercular paleae of various shapes, in two concentric rows. Middle paleae strongly geniculate, blades excavated and margins smooth, pointing outwards; innermost paleae strongly geniculate, with short concave blades and smooth margins, directed inwards. 3–6 pairs of straight nuchal spines often present. Compound (branching) tentacular filaments in series of rows; buccal flaps absent. Palps similar or shorter than operculum. Median organ at dorsal junction of lobes of opercular stalk conspicuous in some species and small or absent in others, with eyespots on lateral margins. Neuropodia of segment 1 with one pair of conical cirri and capillary chaetae. Segment 2 with one triangular-shaped lobe on both sides of building organ. Thoracic branchiae present. Three parathoracic segments. Parathoracic notochaetae lanceolate and capillaries alternating; neurochaetae similar in shape but smaller (Capa et al. 2012).

Remarks. Nishi et al. (2010) and Santos et al. (2011) have recently described new species of Sabellaria and provided a table with chaetal characteristics of the 36 species from around the world. They highlight the variability of certain features within the genus, such as the different geometry and superficial ornamentation of the paleal thecae (especially in the middle row), the presence or absence of a plume or median tooth in the outer paleae, and the presence or absence of nuchal spines. According to Capa et al. (2012) the large intraspecific variation regarding these features, together with the inconsistency of the presence or absence of a median organ among Sabellaria species ( Kirtley, 1994), compromise the assessment of the monophyly of Sabellaria . Therefore, the species analyzed before were not examined observing the form and position of the medium organ. The presence of a medium organ was also reported for some other genera of Sabellariidae and for the genus Megalomma (family Sabellidae ) ( Tovar and Salazar-Vallejo 2008).

According to Capa et al. (2012) all species of Sabellaria share the presence of an

operculum completely divided into two symmetrical lobes, inner paleae being arranged into two symmetrical, semicircular rows (with mid and inner paleae), and with three parathoracic segments. Branchiae on second (thoracic) segment are present (contrary to diagnosis of Nishi et al. 2010). Sabellaria was supposed to share the arrangement of the inner paleae in two concentric rows with Phragmatopoma and Neosabellaria . However, we observed that species of Sabellaria have three concentric rows of inner paleae, while Phragmatopoma has the inner paleae under the middle paleae.