Ophryotrocha macrovifera Paxton & Åkesson, 2010, sp. nov.

Ophryotrocha macrovifera sp. nov.

Figures 1 C, 2D, F, G; 3C–F, H, I; 4A, B; 5A, C; Table 1

Ophryotrocha macrovifera nom. nud. Åkesson, 1975: 378; 1984; Levinton 1983; Pleijel & Eide 1996; Dahlgren et al. 2001; Simonini 2002; Åkesson & Paxton 2005; Simonini et al. 2009; W iklund et al. 2009.

Material examined. Type material: Holotype (AM W36872), complete female specimen, 3.1mm long, 0.35 mm wide without parapodia (preserved) for 18 chaetigers; allotype (AM W36873), complete male specimen, 2.1 mm long, 0.25 mm wide without parapodia (preserved) for 14 chaetigers; 10 paratypes (AM W36874); 10 paratypes (SMNH T- 8030); cultured from specimens collected at Kyrenia, Cyprus, 1972. Other material: Live cultures from same collection.

Description. Length of most live adults 3–4 mm (14–16 chaetigers), maximum length 5 mm (22 chaetigers). Live animals (Fig. 1 C) translucent, preserved opaque white. Pigmentation consisting only of very small lateral red spots on some chaetigers. Prostomium anteriorly rounded, with pair of short, ovate antennae; palps absent (Fig. 2 D); two eyes medially connected (Fig. 3 C, D). Two peristomial achaetous segment-like rings.

Parapodia uniramous (Fig. 2 F), lacking dorsal and ventral cirri, with dorsal protrusion, with retractile ventral lobe; 4–5 supra-acicular simple chaetae, 4–5 subacicular heterogomph falcigers and inferiormost simple chaeta; distal part of simple chaetae and blades of falcigers finely serrated (Fig. 2 G). Pair of pygidial cirri present, pygidial median stylus absent in adults (Fig. 4 A). Rosette glands (Fig. 4 B), one per segment, present mid-dorsally on posteriormost segments of mature animals, up to five in males and females.

Mandibles with elongate shafts and bifid cutting plates with 21–24 tiny pointed teeth at anterior edge (Fig. 3 E, F). Maxillary apparatus of P- and K-type in both sexes, with larval maxillae (Fig. 3 H), falcate P1-forceps (Fig. 3 I), bidentate P2-forceps (Fig. 5 A), K-forceps right bidentate, left falcate (Fig. 5 C).

Reproduction and development. Gonochoristic; chromosomes 2n = 6. Diameter of eggs varies from 150–180 µm in different populations. Tubular egg masses, released larvae with two chaetigers and short pygidial median stylus.

Etymology. The name of the new species refers to its large yolky eggs.

Remarks. The new species was originally collected from Cyprus, Mediterranean Sea in 1972 and identified as a new species through crossbreeding experiments (Åkesson 1975) which have been confirmed by gene sequence studies (Dahlgren et al. 2001; Heggøy et al. 2007; Wiklund et al. 2009). Ophryotrocha macrovifera is unique among the O. labronica group for the following combination of characters: having medially connected eyes and larvae possessing 2–3 pairs of parapodia at hatching.

Distribution. Mediterranean: Cyprus, Genoa, Venice, Italy; Alexandria, Egypt; North Atlantic: Florida, USA, Portugal.