Salmacina tribranchiata (Moore, 1923)

(Figures 8, 12 E–F)

Filograna tribranchiata Moore, 1923: 250 –251. Type locality: Off Santa Rosa Island , California, 69–82 m, small colony on mud, sand and rocks.

Salmacina dysteri tribranchiata .— Monro 1933b: 1090 –1091, Text-figure 31 ( Tagus Cove, Isabela [ Albemarle] Island, Galápagos; from a marine garden sheltered from the sun by an overhanging rock; colony); Berkeley & Berkeley 1941: 56 (Corona del Mar, Monterey Bay and Santa Cruz Island, California; 9–31 m).

Salmacina dysteri (not Huxley, 1855).— Steinbeck & Ricketts 1941: 367 (Bahía de los Ángeles, Baja California, San Francisquito Island, Baja California Sur; encrusting rocks).

Salmacina tribranchiata .— Rioja 1941b: 738 –739, pl. 9, Figs 11 –14 (La Aguada Beach, Acapulco, Guerrero, on Idanthyrsus johnstoni colonies); Hartman 1961: 44 (Southern California); Hartman 1969: 771 –772, Figs 1–6 (off Santa Rosa Island, Southern California, 70–83 m; Figs 1–2 from Fauvel 1927 as Salmacina dysteri; Figs 3–6 from Berkeley & Berkeley 1952); Salazar-Vallejo & López-Muraira 1983: 111 –112 (Bocachibampo Bay, Sonora; intertidal; epifauna of sea urchin Hesperocidaris asteriscus); Salazar-Vallejo 1989b: 200 (Mexican coasts, checklist); Nogueira & ten Hove 2000: 158 –159, Tables 1–2 (discussion and comparison of all Salmacina species); Salazar-Vallejo & Londoño-Mesa 2004: 55 (Tropical Eastern Pacific, checklist); Bastida-Zavala 2008: 43, Figs 10 H–J (Alaska, California, Hawaii, Sinaloa and Oaxaca, intertidal to 116 m); Bastida-Zavala 2009: 529, Fig. 3 X (identification key for Tropical America); ten Hove & Kupriyanova 2009: 91 (worldwide serpulid checklist); Bastida-Zavala et al. 2013: 349 (Oaxaca, checklist); Villalobos- Guerrero et al. 2014: 107 (Sinaloa, checklist).

Filograna implexa (not Berkeley, 1835).— Kudenov 1980: 122 (Sonora coast); Kerstitch & Bertsch 2007: 38, Fig. 63 (field guide of the Gulf of California; 46 m).

Material examined. 3,840 specimens.

Baja California: UANL 7895, 60 spec. (Bahía de los Ángeles, sta. 2: 28°56’52.9”N, 113°33’24.9”W, April 17, 2011, coll. JAL & ARB).

Baja California Sur: UANL 7896, 2,248 spec. ( Marina Santa Rosalía, sta. 1, 27°20’25.2”N, 112°15’56.1”W, April 31, 2011, coll. JAL & ARB); UANL 7897, 1,492 spec. ( Marina Loreto, 26°00’54.9”N, 111°20’21.4”W, April 2, 2011, coll. JAL & ARB).

Oaxaca: UMAR-POLY 832, 11 spec. (Puerto Ángel, pier and beach, May 20, 2007, coll. FCC & SRH); UMAR-POLY 833, 29 spec. (Estacahuite Beach, Puerto Ángel, sample 39, April 9, 2005).

Habitat. Intertidal to subtidal (116 m, Bastida-Zavala 2008). Several samples are from anthropogenic substrates in marinas and ports (from Puerto Loreto and Santa Rosalía, Baja California Sur, from Bahía de los Ángeles, Baja California, and from Puerto Ángel, Oaxaca). Recorded from dead coral, from Oaxaca, and as fouling on PVC plates and hulls, from Alaska, California and Hawaii (Bastida-Zavala 2008). Fouling species.

Distribution. North-Eastern Pacific. From Alaska to California (USA); Hawaii and Mexican Pacific (Moore 1923; Nogueira & ten Hove 2000).

Remarks. Salmacina tribranchiata is a colonial species; in the Santa Rosalía and Loreto marinas, as well as on rocks of a municipal beach of Bahía de los Ángeles, it forms colonies of tens to hundreds of specimens. The species is common in anthropogenic substrates, making transport by means of ships and yachts likely.

It is problematic to distinguish the several nominal taxa of Salmacina; Nogueira & ten Hove (2000, Table 2) gave a noteworthy discussion of the species and the characters used to separate them, sometimes the differences are very subtle or the characters overlap between the species; the use of SEM was recommended by Ben-Eliahu & ten Hove (2011). In this paper we regard specimens of Salmacina from Alaska to the Mexican Pacific to constitute a single species, until a molecular analysis will prove otherwise.