Hydroides crucigera Mörch, 1863

(Figures 3, 11 C)

Hydroides (Eucarphus) crucigera Mörch, 1863: 378, pl. 11, Fig. 8. Type locality: Punta Arenas, Pacific side of Costa Rica, on Margaritifera barbata (now Pinctada Röding sp.), 26 m.

Hydroides californicus Treadwell, 1929: 12 (Baja California); Rioja 1941a: 161 –164 (La Aguada Beach, Acapulco, Guerrero, and Mazatlán, Sinaloa); Rioja 1941b: 733 (same); Salazar-Vallejo 1989b: 199 (Mexican coasts, checklist); Salazar-Vallejo & Londoño-Mesa 2004: 54 (Tropical Eastern Pacific, checklist); Hernández-Alcántara et al. 2008: 48 (mentioned only).

Hydroides crucigera .— Monro 1933b: 1083, Text-figure 26 ( Taboga Island, Panamá, on pier floats) ; Rioja 1944: 409 –414 (synonymization of H. californicus recorded in the Mexican Pacific and duplicity of operculum) ; Rioja 1947a: 215 (La Paz, Baja California Sur, and Topolobampo, Sinaloa); Rioja 1958: 250 –251 (Verde Island and Santiaguillo Island, Veracruz); Straughan 1969: 232 –234 (Pearl Harbor, Kaneohe Bay, Coconut Island and Maili Point, Oahu, Hawaii, samples from 1936 to 1968); Shepherd 1972: 5 (La Paz Bay, Baja California Sur; epifauna on Pinctada mazatlanica [ Hanley]); Long 1974: 28 ( Oahu, Hawaii, 9–36 m, with little coverage on test panels); Kudenov 1975: 228 (Station Beach, Puerto Peñasco, Sonora, bottom of basalt boulders); Bailey-Brock 1976: 77 –78 ( Oahu Island, Hawaii, reef flats, epifauna of mobile substrata [mollusks and crustaceans], boat harbors, lagoons and reef slope); Kudenov 1980: 122 (same as Kudenov 1975); Salazar-Vallejo & López-Muraira 1983: 111 (Bocachibampo Bay, Sonora; intertidal; epifauna of sea urchin Hesperocidaris asteriscus H.L. Clark); Laverde-Castillo 1986: 128 (Málaga Bay, Colombian Pacific); Bailey-Brock 1987: 420 (Hawaii); Laverde-Castillo 1988: 91 (Curichichi, Cabezón and Mayordomo Islands, Málaga Bay, Colombian Pacific, on dead coral and shells); Salazar-Vallejo 1989b: 199 (Mexican coasts, checklist); Bastida-Zavala 1993: 35 (Caimancito Beach and Balandra Beach, Baja California Sur); de León-González et al. 1993: 879 (Puerto Escondido Bay, Baja California Sur, epifauna on the oyster “ Spondylus princeps unicolor Sowerby ”; 30 m); Bastida-Zavala 1995: 24 (Cabo Pulmo Reef, Baja California Sur, on coral; 4–17 m); Gómez et al. 1997: 1071 (Puerto Ángel Beach and La Entrega Beach, Oaxaca, rocks and coral); López-García et al. 1997: 66 (Coiba, Panamá, under rocks, on dead coral and the octocoral Telesto riisei [Duchassaing & Michelotti]); Dean 2004: 165 (list of polychaetes from Costa Rica).

Hydroides crucigerus .— de León-González 1990: 336–337, Fig. 3 e–g ( Punta San Juanico, Baja California Sur; 30 m).

Hydroides cruciger .—Bastida-Zavala & ten Hove 2003: 78–80, Figs 5 A–Q (Baja California, Baja California Sur, Guerrero, Oaxaca, Panamá, Hawaii; 0–8 m) ; Salazar-Vallejo & Londoño-Mesa 2004: 54 (Tropical Eastern Pacific, checklist); Bastida-Zavala 2008: 23, fig. 6E (Hawaii, Guerrero and Oaxaca; 0–4 m); Bastida-Zavala 2009: 534, Fig. 2 A (identification key for Tropical America); ten Hove & Kupriyanova 2009: 53 (worldwide serpulid checklist); Tovar- Hernández et al. 2009b: 330–331, Figs 3 k, 6b-c, 7g-i (fouling in Mazatlán, Sinaloa); Bastida-Zavala et al. 2013: 349 (Oaxaca, checklist); Villalobos-Guerrero et al. 2014: 107 (Sinaloa, checklist).

Material examined. 45 specimens.

Sonora: UMAR-Poly 737, 2 spec. (Puerto Peñasco, June 15, 1981, coll. SSV & JAL).

Baja California: UMAR-Poly 738, 3 spec. (La Gringa, Bahía de los Ángeles cobbles on sand, scarce corals and sponges, 29°N, 113°30’W, 2–3 m in low tide, August 13, 1989, coll. HTH).

Baja California Sur: UMAR-Poly 739, 3 spec. (Punta San Juanico, January 28, 1988, coll. JAL, don. UANL 0359); UMAR-Poly 740, 4 spec. (Concepción Bay, Requesón Beach, May 15, 1988, coll. RBZ) ; UANL 7864 (Puerto Escondido, scraping of pier, sta. 4: 25°48’52.9”N, 111°18’40.4”W, April 20, 2010, coll. JAL) ; UANL 7867 (same, sta. 2: 25°48’53.1”N, 111°18’40.5”W, April 2, 2011, coll. JAL); UANL 7865, 3 spec. ( Marina Cantamar, Pichilingue, sta. 1: 24°16’42.7”N, 110°19’50.4”W, April 22, 2010, coll. JAL); UANL 7866, 2 spec. ( Marina Fonatur, La Paz, 24°07’29.7”N, 110°20’47.1”W, November 14. 2013); UMAR-Poly 741 (La Paz Bay, Comitán Beach, October 18, 1989, coll. RBZ).

Gulf of California: UMAR-Poly 742, 2 spec. (M-Serp-1, IM(N)?, no more data, coll. GGG).

Guerrero: UMAR-Poly 743 (La Quebrada, Acapulco, on Muricanthus, May 25, 2000, coll. AM) . Oaxaca, UMAR-Poly 744 (Chacahua Lagoon, on rock, April 3, 2008); UMAR-POLY 745, 5 spec. (Corralero Lagoon and Panteón Beach, March 22–23 and May 15, 2010, coll. FAG, mixed samples); UMAR-Poly 746 (Panteón Beach, Puerto Ángel, 10 m, November 23, 2005, coll. GRC); UMAR-POLY 747 (Puerto Ángel, June 15, 2010, coll. JPQ & RRB); UMAR-POLY 748 (Estacahuite Beach, Puerto Ángel, April 18, 2005, coll. Yareth & SGM); UMAR- POLY 749 ( Marina Chahué, Huatulco, on rocks, May 22, 2000, coll. RBZ); UMAR-POLY 750, 3 spec. (same, on mollusc, May 22, 2000, coll. RBZ); UMAR-Poly 751, 4 spec. ( Salina Cruz, angler pier, main dock, sta. 4, 1 m, May 26, 2011, coll. SGM et al.); UMAR-Poly 752 (same, hull of the shrimp boat “ Golfo Pérsico ”, 1 m, May 26, 2011, coll. EVP); UMAR-POLY 753 (“sample 85”, Oaxaca, 0–6 m, September 15, 2004) .

Panamá: UMAR-Poly 754, 3 spec. (Diablo Spinning Club, Balboa, June 5, 2002, coll. SSV).

Habitat. Intertidal to subtidal (36 m, Long 1974). On mollusks, rocks and on anthropogenic substrates in marinas and ports from Pichilingue, La Paz and Puerto Escondido, Baja California Sur, and Chahué and Salina Cruz, Oaxaca. Also on the oyster “ Spondylus princeps unicolor ” (de León-González et al. 1993), on dead coral Pocillopora and in rock pools, with salinity range of 19–37 PSU (Bastida-Zavala 2008). Fouling species.

Distribution. Tropical Eastern Pacific. From Gulf of California (México) to Málaga Bay (Colombia); also in Veracruz (Rioja 1958: 251) and Hawaii (Bastida-Zavala & ten Hove 2003).

Remarks. Hydroides crucigera was found both on natural and anthropogenic substrates. The species probably is exotic in Hawaii; Straughan (1969) recorded samples from 1936 to 1968; later, Long (1974) recorded the species from Oahu, collected from 1968 to 1972, and Bailey-Brock (1976) recorded the species from several localities, from reef flats to reef slopes in Hawaii. It is a fouling species with potential to be introduced to other tropical regions by ships.

Rioja (1958: 250–251) recorded Hydroides crucigera (as H. californicus) from two reef islands of Veracruz, Gulf of Mexico; unfortunately his collection was lost.

Nonato & Luna (1970: 99–100, Fig. 106) recorded a specimen as Hydroides californicus from Alagoas coast, Brazil, to 100 m depth; however, the specimen could not be synonymized with H. crucigera because their illustration represents an opercular funnel with 24 bluntly tipped radii, while H. crucigera has 30–50 radii with pointed tips (Fig. 11 C). Also, the lateral spinules are represented as very small, almost triangular, while H. crucigera shows long lateral spinules (Fig. 11 C). By the number of radii and general shape of the spines Nonato & Luna’s material is similar to Hydroides sp. 1 Bastida-Zavala & ten Hove (2002), from the Caribbean, except for the number of lateral spinules, 2–4 pairs in Hydroides sp. 1 and only one pair in the specimen from Brazil.