Pseudochitinopoma occidentalis

Pseudochitinopoma occidentalis (Bush, 1905)

Figs 7F, 8

Hyalopomatopsis occidentalis Bush, 1905: 229–230, pl. 40, figs 3, 22, pl. 44, figs 2, 4, 8–9 (type locality: Virgin Bay, Prince William Sound, southern Alaska, United States; on tubes of Serpula splendens Bush, 1905, now S. columbiana).

Chitinopoma occidentalis – Hartman 1948: 50–51, fig. 12a–f (Alaska, Peninsula; intertidal to 229 m).

Chitinopoma groenlandica (non Mörch 1863) – Berkeley & Berkeley 1961: 663 (Carmel Canyon, central California; 36–55 m).

Pseudochitinopoma occidentalis – Zibrowius 1969a: 7 –9, fig. 2a–g (Canoe Bay, Alaska; Shelton, San Juan Archipelago and Puget Sound, Washington; off Santa Rosa Island and Carmel Canyon in central California; intertidal to 229 m). — Bastida-Zavala 2008: 38 –39, fig. 9A–D (Alaska, Washington, Oregon and California; intertidal to 16 m; on rocky bottoms and PVC plates). — Kupriyanova et al. 2012: 68 –72, figs 7A–E, 8A–E (Canada: British Columbia; United States: Alaska, Washington and California; Mexico: Baja California; intertidal to 157 m; on tubes of Serpula sp., Crucigera zygophora, Vermiliopsis infundibulum (Philippi, 1844), now as V. multiannulata (Moore, 1923) for eastern Pacific records, shells of the brachiopod Laqueus californianus (Koch, 1848), alcyonarians, solitary corals, tunicates, burrowing clams, rock and fouling plates).

Material examined

658 specimens: DH (24) Aug. 2002, AK (66) Jul. 2000, AV (7) Aug. 2000, PW (4) Aug. 2003, KD (358) Aug. 2001, ST (81) Aug. 2001, KT (8) Sep. 2003, WA (75) Aug. 2000, OR (1) Aug. 2000, HB (18) Sep. 2003, SF (12) Sep. 2001 and 2011, MO (4) Sep. 2013.

Additional material

Five specimens: LACMNH N1908, 1 specimen (California, approx. 36°36' N, 121°53' W, Monterey Shale, dredged off Del Monte, 12–16 m, 3 Jun. 1934, coll. E.F. Ricketts, as Ditrupa sp.); LACMNH N1909, 2 specimens (California, approx. 37°12' N, 122°24' W, Moss Beach, Jul. 1933, as? Ditrupa); LACMNH N1910, 2 specimens (California, approx. 37°12' N, 122°24' W, Moss Beach, 1934, as? Ditrupa).

Diagnosis

Tube white, smooth; with a longitudinal ridge; without transverse ridges, peristomes or alveoli. Opercular peduncle smooth, white. Operculum white, spherical or conical (Fig. 7F). Collar with fin-and-blade chaetae (Fig. 9N).

Taxonomic remarks

Pseudochitinopoma occidentalis was the species with the largest distribution in the survey, with 12 localities in the northeastern Pacific, from Dutch Harbor, Alaska, to Morro Bay, California. It was also the second most common species represented on fouling plates; only Hydroides dianthus, a species from the U.S. east coast, was encountered more often (Table 1). Despite its frequency on fouling plates, P. occidentalis has not been reported as NIS elsewhere.

Ecology

Intertidal to 229 m (Hartman 1948; Zibrowius 1969a). Rocky bottoms, on tubes of Serpula columbiana, Crucigera zygophora, Vermiliopsis multiannulata, shells of the brachiopod Laqueus californianus, alcyonarians, solitary corals, tunicates, burrowing clams and PVC fouling plates (Bush 1905; Bastida-Zavala 2008; Kupriyanova et al. 2012).

Distribution

Northeastern Pacific, from Alaska to Ensenada, west coast of Baja California Peninsula (Kupriyanova et al. 2012). In this survey, Pseudochitinopoma occidentalis was abundantly and frequently on fouling plates from Dutch Harbor, Kachemak Bay, Kodiak and Sitka, Alaska, and Puget Sound, Washington; occasionally from Valdez Bay, Prince William Sound and Ketchikan, Alaska, Coos Bay, Oregon, Humboldt Bay, San Francisco Bay and Morro Bay, California (Fig. 8).