Hydroides gracilis
Creators: name: Bastida-Zavala, J. Rolando
name: McCANN, Linda D.
name: Keppel, Erica
name: Ruiz, Gregory M.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Sabellida
Serpulidae
Hydroides
Hydroides gracilis

description: Hydroides gracilis (Bush, 1905)
Figs 4G, 6
Eupomatus gracilis Bush, 1905: 234–235, pl. 27, fig. 9, pl. 34, fig. 25, pl. 37, figs 26–27 (type locality: Pacific Grove, California, United States).
Eupomatus intereans Chamberlin, 1919a: 23 (type locality: Laguna Beach, southern California).
Eupomatus gracilis – Treadwell 1914: 225 (San Pedro and San Diego, southern California).
Hydroides uncinata (non Philippi 1844) – Berkeley & Berkeley 1941: 56 (southern California; on seaweed holdfast); 1958: 405 (west coast of Baja California Peninsula: Tortugas Bay, Baja California Sur).
Hydroides gracilis – Zibrowius 1971: 694 –695 (synonymization of E. intereans and H. uncinata recorded by Berkeley & Berkeley 1941, 1958). — Bastida-Zavala & ten Hove 2003: 89 –92, fig. 13A–V (California and Baja California, Mexican Pacific; intertidal to 5 m; on colony of vermetid Aletes sp., on Trochidae, also from aquaculture tanks and lead filter). — Bastida-Zavala 2008: 27, fig. 6K (California; PVC plates).
Material examined
232 specimens: SF (3) Sep. 2000 and 2001, LB (185) Sep. 2003, MO (5) Sep. 2013, MI (7) Aug. 2013, SD (32) Aug. 2000 and Jul. 2013.
Diagnosis
Tube white; with two longitudinal ridges, with or without peristomes; but no transverse ridges or alveoli. Opercular peduncle smooth, white. Opercular funnel with 16–42 radii with pointed tips (Fig. 4G); verticil with 9–12 smooth spines, curving inwards, without internal, external or lateral spinules or wings (Fig. 4G). Special collar chaetae with two blunt or pointed teeth and smooth distal blade.
Taxonomic remarks
Two tiny specimens have the Hydroides “ priscus ” type opercula (ten Hove & Ben-Eliahu 2005), with only a chitinous funnel instead of the normal funnel and verticil. The abundance of H. gracilis is variable in the fouling community, sometimes occurring at high abundances. Nonetheless, its distribution is restricted to California and the west coast of the Baja California Peninsula.
Ecology
Intertidal to sublittoral (5 m). On holdfast of seaweeds, shells of gastropods (Aletes sp. and Trochidae), and in aquaculture facilities (Berkeley & Berkeley 1941; Bastida-Zavala & ten Hove 2003).
Distribution
California to Bahía Tortugas, west coast of Baja California Peninsula (Bastida-Zavala & ten Hove 2003). In this work, Hydroides gracilis was found abundantly on fouling plates from Long Beach and San Diego, California; and occasionally from San Francisco, Morro Bay and Mission Bay, California (Fig. 6). Hydroides gracilis extends its range northward from Pacific Grove (Bush 1905) to San Francisco, California (140 km).
description: Published as part of Bastida-Zavala, J. Rolando, McCANN, Linda D., Keppel, Erica & Ruiz, Gregory M., 2017, The fouling serpulids (Polychaeta: Serpulidae) from United States coastal waters: an overview, pp. 1-76 in European Journal of Taxonomy 344 on pages 35-36, DOI: 10.5852/ejt.2017.344, http://zenodo.org/record/3834679