Tharyx alaskensis Blake, 2015, new species

• Main Author: Blake, James A.
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2015
• Subjects: Biodiversity; Taxonomy; Animalia; Annelida; Polychaeta; Terebellida; Cirratulidae; Tharyx; Tharyx alaskensis; Arctic; Beaufort Sea; Point Barrow; Prudhoe Bay
• Online Access: https://doi.org/10.5281/zenodo.5664950; http://treatment.plazi.org/id/9A3E87FEEB41FFFCD2F7FEFAFB7CFC88

Tharyx alaskensis new species Figures 19‒20 Chaetozone setosa: Pettibone 1954: 287 ‒288, Fig. 33d, in part. Not Malmgren 1867. Chaetozone cf. gracilis : Busdosh 1984. Not Moore 1923. Material examined. Alaskan Arctic, Beaufort Sea, Prudhoe Bay, coll. M. Busdosh, 0 6 Aug 1983, 70°24.1ʹN, 148°32.3.0ʹW, 2.5 m, push cores, Waterflood 6 project, R/V Annika Marie , Sta. 50-1, holotype (LACM-AHF Poly 6554), 10 paratypes (LACM AHF Poly 6555). Off Point Barrow , coll. G.E. McGinitie, 0 9 Aug 1949, 7 miles offshore, 128 m, stones and gravel, 1 specimen (USNM 1263247); coll. 0 6 September 1949, 7.5 miles offshore, 66 m, removed from growth on rocks, 2 specimens (USNM 1263248); 14 Oct 1949, 4 miles offshore, 53 m, gravel and small stones 1 specimen (USNM 22810). Description. Holotype 11 mm long, 0.7 mm wide for ca. 75 setigerous segments; paratypes of similar size. Body light tan in alcohol, without pigment. Body with dorsum of anterior and middle segments slightly elevated above parapodia; venter somewhat flattened throughout body, with weak ventral groove in posterior 30 segments. First 12‒15 segments narrower, more crowded than middle segments, no moniliform segments except in some juveniles; far posterior expanded region again with narrow, crowded segments (Fig. 20 C). Prostomium triangular, narrow, pointed on anterior margin; eyes absent (Figs. 19 A, 20A); nuchal organs small, crescent shaped notch at posterior lateral margin of prostomium, not pigmented. Peristomium longer than wide, with 2‒3 distinct annulations visible dorsally, depending on preservation (Fig. 20 A), with 2–3 weak divisions ventrally; dorsal midline with a long ridge, extending to end of peristomium (Figs. 19 A, 20A), better developed on some specimens. Paired dorsal tentacles arising from posterior margin of peristomium, first pair of branchiae arising lateral and posterior to tentacles on setiger 1 (Fig. 19 A); second pair of branchiae on posterior margin of setiger 1, subsequent branchiae on following setigers. Parapodia low mounds from which ...