Sabellaria, LAMARCK, 1812

Capa, María, Hutchings, Pat & Peart, Rachael, 2012, Systematic revision of Sabellariidae (Polychaeta) and their relationships with other polychaetes using morphological and DNA sequence data, Zoological Journal of the Linnean Society 164 (2), pp. 245-284 : 268-269

SABELLARIA LAMARCK, 1812

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

Type species: Sabella alveolata Linnaeus, 1767 , by monotypy, collected from France ?

Diagnosis: Although the monophyly of Sabellaria has not being assessed in our analyses, all species share the presence of an operculum completely divided into two symmetrical lobes, inner paleae arranged in two symmetrical, semicircular rows (with mid and inner paleae), and the presence of three parathoracic segments.

Description: Operculum length similar to maximum width, completely divided into two symmetrical lobes; distal disc flat and perpendicular to longitudinal axis. Numerous conical opercular papillae around operculum. Outer paleae numerous, arranged in semicircles; geniculate, with flat blades, smooth lateral edges, and smooth or denticulated distal margin and, sometimes, a midline plume. Inner opercular paleae of various shapes, giving the appearance of two rows arranged in two concentric rows. Middle paleae strongly geniculate with excavated blades and smooth margins, pointing outwards; innermost paleae strongly geniculated, with short concave blades and smooth margins, directed inwards. Nuchal spines, when present, as 3–6 pairs of straight spines. Compound (branching) tentacular filaments arranged in series of rows; buccal flaps absent. Palps similar or shorter than operculum. Median organ at the dorsal juntion of the lobes of the opercular stalk conspicuous in some species and small or absent in others, with eyespots on its lateral margins in the species examined. Neuropodia of segment 1 with one pair of conical cirri and capillary chaetae. Segment 2 with one triangularshaped 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.

Remarks: Nishi et al. (2010) have recently described a novel species of Sabellaria and provide a table with the chaetal characteristics of the 35 species from around the world and highlights 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. 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 . Nevertheless all species of Sabellaria share the presence of an operculum completely divided into two symmetrical lobes, inner paleae arranged in two symmetrical, semicircular rows (with mid and inner paleae), and the presence of three parathoracic segments. Branchiae on second segment (thoracic) are present (contrary to the diagnosis of Nishi et al., 2010). Sabellaria shares with Phragmatopoma and Neosabellaria the arrangement of inner paleae in two concentric rows. All species within the genus are gregarious, capable of forming large colonies and reefs along shores where suitable hydrodynamic and sedimentary conditions occur ( Kirtley, 1994).