Hydroides humilis ( Bush, 1905 )

Bastida-Zavala, J. Rolando, Buelna, Alondra Sofía Rodríguez, León-González, Jesús Angel De, Camacho-Cruz, Karla Andrea & Carmona, Isabel, 2016, New records of sabellids and serpulids (Polychaeta: Sabellidae, Serpulidae) from the Tropical Eastern Pacific, Zootaxa 4184 (3), pp. 401-457 : 422-423

Hydroides humilis ( Bush, 1905)

( Figures 5 , 11 J)

Eupomatus humilis Bush, 1905: 235 –236, pl. 39, Figs 39–40; pl. 44, Fig. 22. Type locality: Guaymas, Sonora; attached to small coral.

Schizocraspedon sp.— Maurer et al. 1988: 48 ( Gulf of Nicoya , Costa Rica; 4 m; specimen revised by Bastida-Zavala 2008: 27). Hydroides humilis .—Bastida-Zavala & ten Hove 2003: 92–93, Figs 15A–J (Baja California, Guerrero and Panamá; 2–3 m) ; Salazar-Vallejo & Londoño-Mesa 2004: 54 (Tropical Eastern Pacific, checklist); Bastida-Zavala 2008: 27, fig. 6L (Guerrero, Oaxaca and Costa Rica; 4–10 m) ; Bastida-Zavala 2009: 535, Fig. 2 J (identification key for Tropical America); ten Hove & Kupriyanova 2009: 53 (worldwide serpulid checklist); Bastida-Zavala et al. 2013: 349 (Oaxaca, checklist). Eupomatus humilis .— Hernández-Alcántara et al. 2008: 48 (mentioned only).

Material examined. Four specimens.

Oaxaca: UMAR-Poly 770, 4 spec. ( Salina Cruz , angler pier, main dock, sta. 4, 1 m, May 26, 2011, coll. SGM et al.).

Habitat. Subtidal, 1–10 m (Bastida-Zavala 2008). Found on an angler pier in Salina Cruz , Oaxaca. Also on mangrove, rock and spiny oysters ( Ostrea iridescens Hanley , O. columbiensis Hanley and Spondylus calcifer [now S. limbatus ]) and cobbles on sand (Bastida-Zavala 2008). Occasionally part of fouling fauna.

Distribution. Tropical Eastern Pacific. Baja California to Panamá (Bastida-Zavala & ten Hove 2003).

Remarks. Hydroides humilis is a tiny and rare species; it probably has gone unseen or has been confused with juveniles of other species as H. brachyacantha , H. inermis or H. deleoni , whose opercula are somewhat similar to those of H. humilis . However, the former species have bayonet collar chaetae with two main teeth only, while H. humilis has collar chaetae with two teeth and a proximal rasp (Bastida-Zavala & ten Hove 2003, Fig. 15h). The specific morphological and chaetal characters should be revised in juveniles of Hydroides spp. to evaluate if the specific status of H. humilis is supported or if the nominal taxon represents a semaphoront (juvenile stage) of some, or several, Hydroides species.

Hydroides humilis was found on mangrove, rocks and oysters. Two specimens revised by Bastida-Zavala & ten Hove (2003: 92), presumably from Panamá or Costa Rica, were found together with Spirobranchus minutus and Ficopomatus miamiensis ( Treadwell 1934) ; the last is a Caribbean species that was recorded as exotic in Mazatlán, Sinaloa and the Pacific of Panamá (Bastida-Zavala 2008).

Figures

FIGURE 2. Distribution of the sabellids Branchiomma bairdi, Megalomma carunculata, Parasabella pallida and Pseudobranchiomma punctata in the Tropical Eastern Pacific, Southern California and Hawaii.

FIGURE 5. Distribution of Hydroides glandifera, H. humilis, H. inermis and H. ochotereana

FIGURE 11. Serpulids in the Tropical Eastern Pacific. A. Hydroides cf. amri, operculum and detail of verticil spine (modified of Bastida-Zavala & ten Hove 2003); B. H. brachyacantha, operculum; C. H. crucigera, operculum; D. H. deleoni, operculum; E. H. dirampha, operculum; F – G. H. elegans, sclerotized operculum in aboral view and fleshy operculum in lateral view; H. H. gairacensis, operculum; I. H. glandifera, operculum; J. H. humilis, operculum.