Diopatra budaevae Paxton & Arias 2017, sp. nov.

Diopatra budaevae sp. nov.

Figures 2 A,B, 3; Table 1

Material examined. Type material. Holotype: (MNCN 16.01 /17809), La Laja beach, Gran Canaria, Canary Islands, 28°03’N – 15°25’W, intertidal, coll. A. Arias, 12 Aug 2012.

Type locality. Eastern North Atlantic, Canary Islands, Gran Canaria, La Laja beach, 28°03’N – 15°25’W, intertidal.

Diagnosis. Prostomium anteriorly rounded with two subovate frontal lips; antennae to chaetiger 9–11; with six to seven ceratophoral rings, lateral projections absent; nuchal grooves crescentic; peristomial cirri absent. Anterior four pairs of parapodia with bidentate pseudocompound hooks with falcate hoods; single postchaetal lobes. Ventral parapodial lobes absent, ventral cirri on four chaetigers. Subacicular hooks from chaetiger 10; pectinate chaetae with 9–15 teeth; spiralled branchiae, first on chaetiger 4, last on chaetiger 16.

Description. Incomplete holotype 7 mm long for 38 chaetigers, 0.7 mm wide. Ethanol stored specimen overall whitish with dorsal colour pattern consisting of brown prostomium, lateral brown spots and intersegmental lines on anterior chaetigers (Figs 2 A, 3A).

Prostomium anteriorly rounded with two subovate frontal lips separated by a small gap (Fig. 3 A). Ventral upper lips oval with papilla-like median section between lips; lower lip without median section. Palps reaching to chaetiger 2, lateral antennae to chaetiger 11, median antenna to chaetiger 9; ceratophores with five to six proximal and a long distal ring, equal to about three proximal rings. Ceratostyles with irregularly distributed slightly raised circular sensory buds, styles tapering to distal ends. Nuchal grooves crescentic. Peristomium slightly shorter than chaetiger 1; peristomial cirri absent (Fig. 3 A).

First four pairs of parapodia modified, slightly prolonged and directed anteroventrally with rounded prechaetal lobe and subdigitate postchaetal lobe (Fig. 3 B, C). Thereafter prechaetal lobe becoming reduced, absent from about chaetiger 8–9. Postchaetal lobe becoming smaller but remaining as small knob. Dorsal cirri subdigitate, longest in branchial region, thereafter becoming gradually shorter and slenderer; ventral cirri subulate on anterior four chaetigers with last being slightly shorter, then replaced by ventral glandular pads. Ventral lobe absent. Spiralled branchiae from chaetiger 4, first two pairs best developed with three to four whorls of filaments, reaching to chaetiger 1–2 when extended anteriorly. Thereafter length of branchiae and number of filaments decreasing rapidly, filaments single from chaetiger 13, absent from 16.

Modified parapodia (chaetigers 1–4) with one to two slender upper simple limbate chaetae and three to four pseudocompound bidentate hooks with short falcate hoods. Shafts appearing smooth when viewed with light microscopy; median hook more robust and with shorter appendage (Fig. 3 D) than remaining ones (Fig. 3 E).

Unmodified parapodia (chaetiger 5 onwards) with pectinate and limbate chaetae. Pectinate chaetae with slightly oblique comb with 9–15 teeth (Fig. 3 F), two to three pectinate chaetae per parapodium in median body region. Limbate chaetae finely serrated in median region, replaced by bidentate hooded subacicular hooks from chaetiger 10.

Mandibles (Fig. 3 G) lightly sclerotized, with wide but short cutting plates; maxillary apparatus (Fig. 3 H) with proximally enlarged carrier; maxillary formula: MxI = 1+1; MxII = 7+8; MxIII = 7+0; MxIV?+10; MxV = 1+1. Tube thin and fragile, composed of mucous secretions with some vegetal material attached crosswise (Fig. 2 B)

Etymology. It is a pleasure to dedicate the new species to Nataliya Budaeva, colleague and friend.

Remarks. Diopatra budaevae sp. nov. differs from other described species without peristomial cirri by the following combination of characters: in being very small, its colour pattern, lacking lateral projections on its ceratophores, having smooth and long antennae, and bidentate pseudocompound hooks with short hoods and smooth shafts (Table 1).

Distribution. The new species is only known from its type locality.