SABELLARIIDAE JOHNSTON, 1865

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 : 256-258

SABELLARIIDAE JOHNSTON, 1865

Diagnosis: Sabellariidae is characterized by some autapomorphies such as the presence of nuchal organs located at the base of palps, presence of tentacular filaments originating from segment 1; uncini without a handle or manubrium and presence of a ‘proventricle’. In addition, a unique combination of the following characters (homoplastic) defines the group: the presence of an operculum formed by the head and two anterior segments, presence of a pair of peristomial palps, presence of a building organ, presence of paleae in the anterior segments, uncini without a rostrum or main fang, segmental branchiae inserted in the parapodia, and intraovarian oogenesis.

Description: Body divided into four regions and consisting of an operculum (head and thorax), parathorax, abdomen, and cauda. Segmentation distinct. Operculum formed by the fusion of the prostomium, peristomium, and first two segments. Head appendages consisting of two peristomial palps; antennae absent and a median organ that sometimes protrudes from operculum edge. Prostomial ocelli present in some taxa. Nuchal organs located at base of palps. Tentacular filaments originating from segment 1 and arranged along ventral side of operculum. Building organ with horseshoe shape present and located below mouth. Parapodial rami unequal. Parapodial lobes, dorsal and ventral cirri absent. Aciculae absent. Thoracic chaetae simple, capillaries or straight, flat, and lanceolate chaetae. Abdominal neurochaetae simple, capillaries or straight, flat, and lanceolate chaetae. Abdominal notopodia with uncini without a hood, rostrum, manubrium or basal process but with a capitium, subrostrum, and subrostral process present. Capitium consists of two lines of 6–9 teeth each. Pygidial cirri absent. Parapodial branchiae present on most segments along body. Circular muscles present and longitudinal ones grouped in bundles. Lateral organs absent. Stomodaeum without buccal organ. Gut as a straight tube, with a ‘proventricle’ in anterior abdominal segments. Gular membrane absent. Head kidney protonephridia and adult segmental organs, metanephridia with podocytes and terminal monociliated cells. An anterior pair of excretory and posterior gonoducts present. Circulatory system closed; heart body absent and blood without cells. Nervous system subepidermal; brain without mushroom bodies. Species studied to date are gonochoric, broadcast spawners and with external fertilization. Females with discrete ovaries in posterior segments where oogenesis takes place. Males with rounded head sperm. Larvae planktotrophic and with prototroch, telotroch, and neurotroch ciliary bands together with an apical turf. Tube made out of mucus and sediment particles.

KEY TO SABELLARIIDAE GENERA

1. Opercular lobes completely fused........................................................................................................2 Opercular lobes partially fused ................................................................................................................ 4 Opercular lobes completely divided in two lobes..........................................................................................5

2. Outer row of opercular paleae with flattened blades.......................................................... Phalacrostemma Outer row of opercular paleae with cylindrical blades..................................................................................3

3. Tentacular filaments simple, resembling opercular papillae. Four parathoracic segments........... Bathysabellaria Tentacular filaments compound (numerous and arranged in transverse rows). Three parathoracic segments ......................................................................................................................................... Neosabellaria

4. Outer paleae with straight blades. Tentacular filaments simple, resembling opercular papillae. Palps longer than operculum ................................................................................................................................... Tetreres Outer paleae geniculate, with shaft and blades forming an angle. Tentacular filaments compound (numerous and arranged in transverse rows). Palps shorter than half of length of operculum ...................................... Gunnarea

5. Opercular disc (distal end) clearly oblique to longitudinal margin (e.g. Fig. 8B ), with paleae arranged in a dorsal slope from lateral view...........................................................................................................................6 Opercular disc flat, with paleae arranged perpendicular to longitudinal axis (e.g. Fig. 8A ) ................................. 7

6. Outer paleae with straight and flattened blades and smooth margins. Four parathoracic segments ............................................................................................................................................... Lygdamis Outer paleae with straight and flattened blades with large and pointed denticles on margins. Three parathoracic segments ............................................................................................................................... Idanthyrsus

7. Blade of inner paleae cylindrical, resembling spines...............................................................................8 Blades of inner paleae different (flat or concave).......................................................................................10

8. Nuchal spines straight ................................................................................................ Mariansabellaria Nuchal spines with bent tips (hooks)................................................................................................. Gesaia

9. Buccal flaps present; outer paleae arranged in spirals........................................................ Phragmatopoma Buccal flaps absent; outer paleae arranged in semicircles ........................................................................... 10 10. Outer paleae with flat blades and smooth margins. Nuchal spines, if present, straight and without limbations .............................................................................................................................................. Sabellaria Outer paleae with flat blades and large pointed denticles. Nuchal spines with bent tips (hooks) and limbation of convex side................................................................................................................................ Paraidanthyrsus

Figures

Figure 8. Photographs of preserved specimens: A, operculum and anterior segments, lateral view, Sabellaria sp. nov. 2; B, operculum and anterior segments, lateral view, Lygdamis giardi; C, detail of opercular papillae, Lygdamis indicus; D, head and thoracic appendices, Idanthyrsus australiensis; E, head and thoracic appendices, Sabellaria sp. nov. 2; F, operculum and anterior segments, ventral view, Phalacrostemma sp. nov.; G, head and thoracic appendices, L. giardi; H, head and thoracic appendices, L. giardi; I, median organ with lateral ocelli, I. australiensis; J, head and thoracic appendices, Bathysabellaria spinifera; K, operculum and paleae, dorsal view, Tetreres robustus; L, operculum and thoracic segments, lateral view, B. spinifera; M, operculum and anterior segments, lateral view, T. robustus. Abbreviations: b, branchia; b2, branchia segment 2; bo, building organ; cn 1, cirrus neuropodia segment 1; chn1, chaetae neuropodium segment 1; dap, dorsal papilla; es, eyespots; ip; inner paleae; li, lips; mo, mouth; mor; median organ; mr, median ridge; ns, nuchal spines (hooks); op, outer paleae; opa, opercular papillae; p, paleae; pa, palp; pl, oral plates; tf, tentacular filaments.