Sternaspis buzhinskajae, Salazar-Vallejo, Sergio I., 2014

Salazar-Vallejo, Sergio I., 2014, Three new polar species of Sternaspis Otto, 1821 (Polychaeta: Sternaspidae), Zootaxa 3861 (4), pp. 333-344 : 334-337

Sternaspis buzhinskajae n. sp.

Figs 1 , 2

Sternaspis fossor : von Marenzeller, 1890: 6–8, Pl. 1, Figs 4, 4 A, B; Sendall & Salazar-Vallejo, 2013: 34–36, Fig. 1 B (not Fig. 9) (non Stimpson, 1853).

Sternaspis scutata: Pettibone, 1954: 309 –310, Fig. 35a, b (partim, non Ranzani, 1817)

Type material. Beaufort Sea. Alaska. Holotype ( CAS 9853), R.V. Ivik, off Point Barrow, Sta. 51-34, 3.5–5.0 m, 2 Aug. 1951, J. Böhlke, coll. One paratype ( CAS 22618), Camden Bay, Sta. D5B 105 (70°02'48" N, 144°54'24" W), 10 m, 20 Aug. 1977, J. Cordell & A.C. Broad, coll. (19 mm long, 8 mm wide; left shield plate 4.0 mm long, 3.8 mm wide). Bering Sea. Ten paratypes ( CAS 19261), juveniles, NNW off Amak Island, Alaska Peninsula, Sta. MB19 18 (56°40' N, 163°57' W), 76 m, 24 May 1976, M. Freeman, coll. (7.5–11.0 mm long, 4–6 mm wide; left shield plate 2.2–2.7 mm long, 2.1–2.8 mm wide). Four paratypes ( CAS 19372), NNW Saint Paul Island, Sta. MB 64 24 (58°00' N, 171°05' W), 90 m, 27 May 1976, M. Freeman, coll. (10.0–13.0 mm long, 5.5–7.0 mm wide; left shield plate 2.5–3.4 mm long, 2.7–3.4 mm wide).

Additional material. Bering Sea. 33 specimens ( LACM 5711), dried-out, Aleutian Cruise, Sta. 83 (63°06' N, 171°42' W), off S end of Saint Lawrence Island, 55 m, sandy silt, 8 Aug. 1949 (9–15 mm long, 3–5 mm wide, ventro-caudal shield left plate 2.7–4.3 mm long, 2.7–4.5 mm wide). Two specimens ( LACM 5712), partly dehydrated, one with introvert exposed, Aleutian Cruise, Sta. 148 (57°34' N, 166°36' W), N off Umivak Island, 66 m, sandy silt, 27 Aug. 1949 (specimen with introvert exposed 15 mm long, 7 mm wide, ventro-caudal shield left plate 5 mm long, 4.5 mm wide). 16 specimens ( LACM 5710), dried-out, Aleutian Cruise, Sta. 153 (56°45' N, 166°18' W), NW off Umivak Island, 73 m, sandy silt, 27 Aug. 1949 (5.5–10.0 mm long, 4.0– 7.5 mm wide, ventrocaudal shield left plate 1.9–3.5 mm long, 1.9–3.5 mm wide). Chukchi Sea. Four specimens ( LACM 5709), partly dehydrated, Aleutian Cruise, Sta. 108 (70°05' N, 165°22' W), NW off Icy Cape, 38 m, sandy silt, 18 Aug. 1949 (8–12 mm long, 3–5 mm wide, ventro-caudal shield left plate 2.3–3.4 mm long, 2.3–3.3 mm wide). 18 specimens ( ZIRAS 1448 108), North Pole Field Station, St. 15 (71°50.2' N, 175°54.0' W), 63 m, 10 Aug. 1946, A.P. Andriyashev, coll. (8.9–26.5 mm long, 6.0– 13.5 mm wide, left shield plate 1.0– 5.5 mm long, 1.0– 6.3 mm wide). Okhotsk Sea. 11 specimens ( ZIRAS 28053 4), juveniles, damaged, off New Siberian Islands (77°20.5' N, 135°47' E), 38 m, 10 Nov. 1901 (11–15 mm long, 5.5–11 mm wide; left shield plate 2.3–3.5 mm long, 3.0–4.0 mm wide).

Description. Holotype (CAS 9853) complete ( Fig. 1 A). Body pale brownish, introvert slightly pinkish, laterally broken exposing inner organs, constriction or waist segments well-defined, visible dorsally; ventro-caudal shield dark red with darker marginal band, margins pale or whitish. Introvert integument eroded, abdomen finely papillose. Body 22 mm long, 6.5 mm wide, abdomen 16 mm long; left ventro-caudal shield plate 5.3 mm long, 5.0 mm wide.

Prostomium smooth, oblong, wider than long, projected, covered by exposed pharynx, visible in side view. Eyespots not seen. Peristomium narrow, covered by pharynx; papillae small, abundant, covering peristomium, extending to margin of first chaetiger.

Introvert partly covered by pharynx and inner organs; chaetigers with 12–14 brassy falcate hooks ( Figs 1 B, 2E), most with tips broken, with subdistal darker areas; few with mucrons. Genital papillae large, cirriform, corrugate, with similar pigmentation as abdomen, emerging from intersegmental area between segments 7 and 8. Anterior abdomen with 7 segments, papillae mostly eroded, arranged in groups; first four abdominal segments with two alternate series, posterior segments with a single series. Capillaries not seen.

Ventro-caudal shield surface with ribs and concentric lines ( Fig. 1 A, C). Anterior margins round, markedly projected, anterior depression deep. Anterior keels half as long as anterior projections. Suture visible throughout shield. Lateral margins rounded, expanded posteriorly, smooth. Fan markedly projecting posteriorly beyond posterior corners level, median notch deep, wide; lateral notches shallow, margin markedly crenulated forming single, large semicircular projections per rib.

Marginal chaetal fascicles damaged, many chaetae broken, 10 lateral and 7 posterior fascicles with all chaetae arranged obliquely. Peg chaetae mostly broken, bases visible, some long delicate chaetae still attached.

Branchiae abundant, very thin, long, coiled; interbranchial papillae long, curled, often thinner than branchiae. Branchial plates anteriorly wider, posteriorly tapered, rounded. Anal peduncle not exposed.

Variation. Smaller specimens paler ( Fig. 2 A, C), with prostomium hemispherical and fewer introvert hooks per chaetiger. Ventro-caudal shield with anterior projections, fan less prominent, and anterior keels variably visible ( Fig. 2 B, D). Fan’s median notch visible in smallest specimens, markedly deeper than laterals and having crenulate margins, but less developed projections per rib than in r large specimens ( Fig. 1 F). Bodies ranged from 6–19 mm long, 1–8 mm wide; left shield plate 1–4 mm long, 1–3.8 mm wide.

The pigmented, concentric bands are variable; sometimes the orange to red contrast is more marked than in other specimens, especially among ZIRAS materials (Chukchi and Okhotsk Seas), but the general shield shape is relatively consistent as described above. Another difference is the relative thickness of integument covering the shield, being thicker in the ZIRAS specimens but again, because the overall shield shape is consistent, they are regarded as belonging to the same species.

Etymology. This species is named after Dr. Galina Buzhinskaja , from the Zoological Institute, Russian Academy of Sciences, Saint Petersburg, in recognition of her many publications on polychaetes and especially because of her unlimited generosity and support to my research activities. The epithet is a noun in the genitive case formed after the stem of her last name (buzhinskaj).

Remarks. The California Academy of Sciences specimens of S. buzhinskajae n. sp. were identified as S. scutata ( Ranzani, 1817) , but they differ because in S. buzhinskajae the shield has larger, usually exposed anterior keels, and the fan is more projected posteriorly beyond the lateral corners. It is also similar to S. fossor ( Stimpson, 1853) , but in S. buzhinksajae the lateral notches are deeper, the fan is more markedly projected, and its margin is strongly crenulated to denticulate.

Sternaspis buzhinskajae n. sp. groups with S. annenkovae Salazar-Vallejo & Buzhinskaja, 2013 , S. fossor Stimpson, 1853 and S. islandica Malmgren, 1867 because their shields have distinct radial ribs and concentric lines, deep median notch, and posterior corners poorly defined. However, S. buzhinskajae n. sp. is closer to S. islandica and differs from the other two S. fossor and S. annenkovae because its anterior keels are usually exposed, and its fan is markedly projected, whereas in the two other species anterior keels are rarely exposed, and their fans are barely projected. Also the shield varies between S. buzhinskajae and S. islandica ; in S. buzhinskaja n. sp. the anterior corners are at least as long as the anterior keels, and the fans posterior margin is crenulate to dentate, whereas in S. islandica the anterior corners are just as long as anterior keels, and its fan has a smooth to crenulated posterior margin.

The specimens recorded by Moore (1908) as S. scutata from the Gulf of Alaska, which were regarded as the same as those found in Japan, were found in deeper water (238–474 m), or those recorded by Wesenberg-Lund (1950a, b, 1951, 1953) from Greenland, have not been examined.

Distribution. Arctic Ocean; Okhost, Chukchi, Bering and Beaufort Seas, in 3.5–90.0 m.

Figures

FIGURE 1. Sternaspis buzhinskajae n. sp., holotype (CAS 9853). A. Complete specimen, ventral view (arrow points to genital papilla), B. Frontal view of anterior end, C. Close-up of ventro-caudal shield. Scale bars. A: 1.5 mm, B: 1.1 mm, C: 0.8 mm.

FIGURE 2. Sternaspis buzhinskajae n. sp. A – D. Two paratypes (CAS 19372), A. Complete specimen, ventral view, B. Closeup, ventro-caudal shield, C. Complete specimen, ventral view, D. Same, ventro-caudal shield, frontal view, E – F. Paratype (CAS 22618), E. Anterior end, frontal view, F. Ventro-caudal shield, frontal view. Scale bars. A: 1.4 mm, B, D: 1.1 mm, C: 2.1 mm, E: 0.8 mm, F: 1 mm.

FIGURE 4. Sternaspis sendalli n. sp. A – C. Holotype (BMNH 1930.10.8.2372 – 2400), A. Complete specimen, ventral view, B. Anterior end, left side view, C. Same, ventro-caudal shield, frontal view, D – F. Smaller paratype (BMNH 1930.10.8.2372 – 2400 p), D. Ventro-caudal shield, frontal view, smaller one, E. Ventro-caudal shield, frontal view, medium one, F. Ventro-caudal shield, larger one. Scale bars. A: 1.7 mm, B, E: 1.1 mm, C: 0.8 mm, D: 0.9 mm, F: 1.2 mm.