Paraidanthyrsus, KIRTLEY, 1994

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 : 267

PARAIDANTHYRSUS KIRTLEY, 1994

Paraidanthyrsus Kirtley, 1994: 80 .

Type species: Hermella quadricornis Schmarda, 1861 , from New Zealand .

Diagnosis: Paraidanthyrsus is characterized by the presence of geniculate outer paleae with flat blades and nuchal hooks with a limbation on the convex side.

Description: Operculum with length similar to width, lobes completely divided into two free lobes and distal disc perpendicular to longitudinal axis and numerous short papillae around its perimeter. Outer paleae arranged in semicircles, geniculate, with flat blades and margins with long and pointed denticles and without a distal plume. Inner paleae in a single row, arranged in semicircles, strongly geniculate, with flat blades and tips directed inwards. Two or three pairs of nuchal hooks with bent tips (hooks) and limbation of the convex side. Tentacular filaments compound (branching) arranged in more than eight rows; buccal flaps absent. Palps similar in length to operculum. Conspicuous median organ at the dorsal juntion of the lobes of the opercular stalk absent. Segment 1 with a small and rounded cirrus on both sides of building organ and with capillary chaetae on the neuropodia. Segment 2 with two triangular-shaped lateral lobes. Thoracic branchiae present. Three parathoracic segments. Parathoracic notochaetae lanceolate and capillaries, similar in shape but smaller in neuropodia. Abdominal branchiae absent in posterior abdominal segments.

Remarks: In his revision of the Sabellariidae, Kirtley (1994) suggested that this monospecific genus was probably related to Idanthyrsus based on the presence of straight, flattened, denticulated paleae. In any of the resulting topologies Idanthyrsus and Paraidanthyrsus are recovered as sister taxa or not even in the same clades, and differently Paraidanthyrsus is nested within the apomorphic sabellariid as the sister-group to Gunnarea and basal to a clade formed by Gunnarea , Neosabellaria , Phragmatopoma , and Sabellaria , and supported by the presence of geniculate inner paleae.