Polycirrus dubius Day, 1973

Glasby, Christopher J. & Hutchings, Pat, 2014, Revision of the taxonomy of Polycirrus Grube, 1850 (Annelida: Terebellida: Polycirridae), Zootaxa 3877 (1), pp. 1-117 : 51

Polycirrus dubius Day, 1973

Fig. 25a–d

Polycirrus eximius dubius Day, 1973: 123 , fig. 16q.

Type locality. North Carolina, USA .

Material examined. HOLOTYPE: USNM 43130 , USA, off Beaufort , North Carolina, 34°43ʹ24.97ʺ N, 76°26ʹ19.61ʺ W, 18 m on coral.

Description. Alcohol-preserved animal, yellowish brown in colour, 13 mm long, 2 mm wide excluding buccal tentacles, complete with about 80 segments posteriorly segmentation compact. Sex unknown. Large sections of the epidermis have been removed anterodorsally to reveal the nephridia.

Dorsum anteriorly faintly ridged. Venter anteriorly with mid-ventral groove and discrete ventro-lateral pads; pads deeply incised (corrugated), extending from segment 3 to 10. Mid-ventral groove from segment 4 ( Fig. 25a ).

Buccal tentacles missing, arising at junction between prostomium and upper lip. Prostomial ridge distinctly curved, U-shaped, extending laterally along anterodorsal base of upper lip. Upper lip trefoiled with lateral blindly-ending enclosed diverticulae, margin of medial lobe convoluted; oral surface glandular and ciliated. Inner lower lip subtriangular (hidden by upper lip); outer region flat, shield-like, subtriangular and pointing toward mouth, strongly rugose, extending posteriorly to segment 3. Achaetous segments visible dorsally but obscured by expanded outer lower lip ventrally.

Notochaetigerous segments 34, extending to segment 36. Notopodia more-or-less rectangular, prechaetal lobe low, postchaetal lobe digitiform, slightly longer than prechaetal ( Fig. 25b ). Notochaetae within a chaetiger of one type (chaetigers 4, 14 examined), gradually elongating from dorsal to ventral, very finely hirsute, subdistally slightly expanded slightly, posteriorly same form as those anteriorly ( Fig. 25c ). Neurochaetae beginning on segment 11. Neuropodial tori erect rectangular pinnules, differ along body becoming more erect posteriorly; extreme posterior ones becoming small. Uncini with short neck and straight to convex base (Type 1), teeth above main fang arranged in double transverse series (MF:1:8–11) enlarged median tooth above main fang present, subrostral process present as low rounded protuberance ( Fig. 25d ).

Nephridial papillae present, cylindrical, decreasing in size posteriorly. Pre-gular membrane nephridial papillae present on segments 3–4. Post-gular membrane nephridial papillae present, on segments 5–8, decreasing in size posteriorly; situated at ventral base of notopodia. Pygidium smooth ring.

Comments. We have elevated the subspecies Polycirrus eximius dubia to a full species, P. dubia ; it differs from the stem species P. eximius Leidy, 1855 in the number of notochaetigerous segments (25 in P. eximius ; 34 in P.dubius ), a difference that well exceeds normal intraspecific variation ( Table 1 ). Polycirrus eximius is herein regarded as a species inquirenda.

Figures

FIGURE 25. Polycirrus dubius Day. Holotype USNM 43130. a. Anterior ventral view. b. Left side posterior lateral view of notopodium, chaetiger 4. c. Notochaeta illustrated at x40 and x100 from chaetiger 4. d. Lateral and frontal views of uncini from posterior chaetiger. Scales in mm as indicated.