Polycirrus readi, Lavesque & Hutchings & Daffe & Londoño-Mesa, 2020

Lavesque, Nicolas, Hutchings, Pat, Daffe, Guillemine & Londoño-Mesa, Mario H., 2020, Revision of the French Polycirridae (Annelida, Terebelliformia), with descriptions of eight new species, Zootaxa 4869 (2), pp. 151-186 : 177-182

Polycirrus readi n. sp.

Figures 18–19 , Table 2.

Material examined: Holotype: MNHN-IA-TYPE 2019, one complete specimen, Mediterranean Sea , Corsica Cape, 42°44’23”N, 9°28’41”E, 60 m depth, May 2019 . Paratypes: AM W.53126, one complete specimen, Mediterranean Sea , Corsica Cape, 43°01’18”N, 9°24’30”E, 18 m depth, May 2019, posterior part used for molecular analysis, mounted for SEM.

Additional material: MNHN-IA- PNT 124, one complete specimen, Mediterranean Sea, Calvi, 42°34’48”N, 8°43’45”E, 40 m depth, August 2011.

Description. Small specimens except MNHN-IA- PNT 124, holotype 8.3 (4.1–14.5) mm long and 0.6 (0.4–0.9) mm wide.

Transverse prostomium attached to dorsal surface of base of upper lip; basal part as thick crest across dorsum, extending laterally and dorsally, covering SG1 laterally and terminating lateral to lower lip. Buccal tentacles of two types, long and thin tentacles uniformly cylindrical, long and thick ones deeply grooved ( Figs 18 A–D; 19A). Peristomium forming lips; upper lip elongate, longer than wide, with single median lobe only, triangular, convoluted ( Figs 18B, D ; 19A ); lower lip oblong, longer than wide, very glandular, ridged ( Figs 18B, D ; 19A ).

SG1 and 2 reduced, SG1 visible dorsally, SG2 dorsally and laterally; body slightly broader until SG6, then tapering until SG10, then of relatively uniform width (larger than anterior part) until mid-body, posterior end tapering ( Fig. 18A ). Ventro-lateral inflated pads well-defined from SG3 to SG9 (SG10), smooth, with transverse ridges on largest specimen, subsequent ones less conspicuous until SG12 (SG15) ( Figs 18 A–D; 19A). Large anterior midventral groove from S3, present until end of body as a stripe ( Figs 18B, D ; 19A ).

Notopodia from SG3, extending for 17 (13) segments, until SG19 (SG15); distinctly elongate, rectangular, first pair slightly shorter, bilobed, postchaetal lobe conical with rounded tip, larger than prechaetal one ( Fig. 19B ). Winged notochaetae of two different lengths ( Figs 18E ; 19 B–C). Neuropodia beginning from SG10 (SG9); uncini with short occipitum and slightly convex base (Type 1), crest with single elongate and sharp tooth on first row above main fang, with one additional rows of 4–5 short, irregularly sized teeth ( Fig. 19D ), subrostral process present as a protuberance ( Fig. 18F ).

Nephridial and genital papillae not seen.

Pygidium rounded with pointed tip.

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Etymology. This species is dedicated to Dr. Geoff Read for his outstanding contribution to WoRMS website and for sharing his immense knowledge on the annelida.net forum.

Habitat. 16–60 m depth, among rocks and dead leaves of Posidonia sp.

Type locality. Corsica Cape , Mediterranean Sea .

Distribution. Known from type locality only.

Remarks. Polycirrys readi n. sp. is characterized by the presence of notopodia extending on 13–17 segments and neuropodia from SG9–10, which is similar to P. norvegicus (notopodia on 14–20 segments neuropodia from SG10–12) and P. elisabethae (notopodia on 16 segments and neuropodia from SG11) ( Table 2).

However, P. readi n. sp. differs from P. norvegicus by the presence of a mid-ventral groove from S3 (instead of S4 for P. norvegicus ), of notopodia with conical postchaetal lobe (instead of digitiform lobe for P. norvegicus ) and of uncini with a main tooth always present and secondary row of teeth above it (instead of teeth arranged in a single transverse row, with or without main tooth for P. norvegicus ). Finally, the two species are described from very different geographical areas (North Sea for P. norvegicus , Mediterranean Sea for P. readi n. sp.).

Polycirrus readi n. sp. differs from P. elisabethae by the shape of lower lip (oblong and longer than wide for P. readi n. sp., subtriangular and wider than long for P. elisabethae ), by the shape of ventro-lateral pads (very inflated for P. readi n. sp., discrete for P. elisabethae ), by the appearance of the mid-ventral groove (from S3 for P. readi n. sp., from S 4 P. elisabethae) and by the dental formula of uncini (secondary row with 4–5 teeth for P. readi n. sp., with 11–15 teeth for P. elisabethae ).

Figures

FIGURE 18. Polycirrus readi n. sp., additional material MNHN-IA-PNT 124 (A–B), holotype MNHN-IA-TYPE 2019 (C–D). A. Entire specimen, lateral view; B. Anterior end, ventral view, methyl green staining; C. Anterior end, lateral view; D. Anterior end, ventral view.; E. Notochaetae, SG8, 40x objective; F. Uncini, posterior chaetiger, 40x objective.Abbreviations: Bt, buccal tentacles; Ll, lower lip; Ul, upper lip; Sp, subrostral process.

FIGURE 19. Polycirrus readi n. sp., SEM paratype AM W.53126. A. Anterior end, ventral view; B. Notopodia, SG5, ventral view; C. Notochaetae, SG5; D. Abdominal uncini. Abbreviations: Ll, lower lip; Pcl, postchaetal lobe, Ul, upper lip. Numbers refer to segments.