ISSN 1809-127X (online edition) © 2011 Check List and Authors Chec List Open Access | Freely available at www.checklist.org.br Journal of species lists and distribution PECIES S the Gulf of California, México OF Holoplanktonic mollusks (Mollusca: Gastropoda) from ISTS * L Orso Angulo-Campillo , Gerardo Aceves-Medina and Raymundo Avedaño-Ibarra Centro Interdisciplinario de Ciencias Marinas-IPN, Departamento de Plancton y Ecología Marina. Avenida Instituto Politécnico Nacional s/n. Col. *Corresponding author E-mail: [email protected] Playa Palo de Santa Rita. Apdo. 592. C.P. 23096. La Paz, Baja California Sur, México. Abstract: species, including We compiled 39 new arecords checklist and of two holoplanktonic range extensions mollusks within obtained the Gulf. from seven oceanographic surveys performed between 2005 and 2007 in the Gulf of California, México. The checklist comprises five orders, 15 families, 28 genera and 62 Introduction Materials and Methods The Gulf of California is a semienclosed basin, located the Class Gastropoda, in which the species are not large bewteen 32°00’ – 24°40’ N and bounded by the continental The true holoplanktonic mollusks are represented by coast of México and the Baja California Peninsula (Figure 1). One of the most important features of the Gulf is the enough or powerful enough swimmers to be classifiedet al. wide range of sea surface temperatures (SST). In the 1997),as nektonic. and live Of inthe the approximately open oceans 40,000of the world, marine primarily species northern region, the annual SST range is 9 to 38°C, while atof tropicalgastropods, and subtropicalonly 244 are latitudes holoplanktonic (Bé and Gilmer (Spoel 1977). in the southern region is 22 to 31°C (Soto-Mardones et al. 1999). The Gulf of California is hydrographically complex, Another characteristic of this group is its affinity for including local upwelling on the continental coast caused andcertain Pierrot-Bults water masses 1979), (Fager and andalso McGowanas indicators 1963), of climate which by north-west winds during winter and low intensity has resulted in their use as zoogeographicet al .markers 2008). (Spoel upwelling on the peninsular coast associated with south- east winds during summer (Alvarez-Borrego 1983). Water inchange two andmajor ocean groups acidification according (Fabry to Spoel et al. (1997); masses are warm but the Gulf water has high salinity PterotracheidaeThe holoplanktonic (including mollusks Atlantidae, are comprehendedCarinariidae, and Pterotracheidae) and Ophistobranchia (including Thecosomata, Gymnosomata and Nudibranchia). (>34.9) and flows southward along the peninsular coast, (Alvarez-Borrego1983;while tropical Pacific waterLavín ethas al. lower1997) salinity (34.65< to>34.85)Seven oceanographicand flows northward surveys along were the conducted mainland in coast the Few faunistic surveys of holoplanktonic mollusks recordedhave been 34 completed species south in theof Cabo North San Pacific Lucas; relatedMcGowan to holoplanktonic mollusks. McGowan and Fraundorf (1966) Gulf of California between March 2005 and August 2007. Four of those surveys (March, May, September 2005 and Hidalgo(1967), reported(1989), 33recorded species eightfrom thespecies California from Current Bahía JanuaryMarch 2006) and Agust, were named2007) were CGC (forcalled Circulación GOLCA (for en Golfo el Golfo de Magdalenabetween November between 1949May andand June October of 1984. 1952; In Sánchez-the Gulf California).de California) The and station the remaining codes in Figuresthree (November 1 A-B consist 2005, of either CGC or GOLCA, followed by two digits indicating the year in which the survey was done and the two denoting wereof California done by not Abbott a single (1974) formal whom study reported of holoplanktonic two species. the month. The GOLCA surveys were completed onboard Poormanmollusks andhas Poormanbeen made. (1988) However, recorded sporadic four species records in the oceanographic vessel “El Puma” from the Universidad one species in the mouth of the Gulf; and Angulo-Campillo Pto. San Carlos (Sonora), Fernández-Alamo (1996) found 4-01-144).Nacional Autónoma The CGC desurveys México were (grants conducted CONACyT-SAGARPA onboard the vesselsS007-2005-1-11717 “Alejandro de andHumbolt CONACyT-FOSEMARNAT and Altair” from Secretaría 2004- (2005) recorded two species near La Paz. The first paper that dealts specifically with the heteropods of the Gulf was beenSeapy reportedand Skoglund from the(2001), Gulf whoof California. recorded The10 species.present de Marina Armada de México (grant CGPI-2005053). In summary, 19 species of holoplanktonic mollusks have to aA maximumtotal of 246 depth plankton of 220 samples m, following were obtainedthe sampling with oblique tows using Bongo nets with 505-µm mesh size, study extends the previous studies, reporting 63 species. Check List | Volume 7 | Issue 3 | 2011 337 Angulo-Campillo et al. | Holoplanktonic mollusks, Gulf of California, México 1). There were two northward range extensions (Firoloida method detailed by Smith and Richardson (1979). The desmaresti57% of the totaland richnessPhylliroe recorded bucephala during). The the studythecosomes (Table holoplanktonic mollusks were removed from the net samples, fixed and preserved in 96% ethanol to avoid anddeterioration Seapy (1999), of the Spoel shell. and The Dadon specimens (1999), were Seapy identified and Lalli were most abundant (61.4%) followed by the heteropods (2007),using Seapy Spoel (1990), et al. (1997). Spoel and Also, Boltovskoy specimens (1981), of heteropods Richter (37.3%), the gymnosomes and nudibranchs were and some gymnosomes were selected for dissection, and uncommon (>1.3%). Only 14 species represented together particularly the radula was prepared for examination for 90% of the total abundance, whose individual abundances scanning electron microscopy (SEM) following the method theeach Gulf exceeded of California 2% of thegiven total here (Table is the 1). most extensive yet by Geiger et al. (2007). The specimens were deposited in The taxonomic list of holoplaktonic mollusks from presentpresented. species The 62 list taxa is undoubtedly identified represent incomplete approximately due to the the The“Colección systematic Científica list of despecies moluscos was made holoplanctónicos following Spoel del fact30% that of thethe selectivityholoplnaktonic of the mollusksampling worldtechnique fauna. did Thenot andPacífico Dadon Mexicano” (1999), aboveat CICAMAR-IPN. family level according to Bouchet allow catches of some neustonic species (e.g. janthinids). Within the Pterotracheoidea, the family Atlantidae was the best represented in the Gulf of California. There Resultsand Rocroi and (2005). Discussion are 19 valid species worldwide, from which 17 occurs A total of 25,404 organisms were identified, grouped althoughin the Pacific the smallestOcean (Seapy area of2010) this andenclosed they aresea, included its high in five orders, four suborders, 15 families, 28 genera environmentsnow in the Gulf and of California.Thisdiversity allows finding the presence is relevant of all since the and 62 species (Table 1). The Heteropoda contained 25 species (39.7%), the Cephalaspidea one species (1.6%), The Carinariidae contain nine species of which four the Thecosomata 21 species (33.3%), the Gymnosomata werespecies recorded found in and the Pterotracheidae,Pacific Ocean. three species of the 13 Thirty-eightspecies (20.6%) new andrecords the Nudibranchiawere found inthree the speciesGulf of (4.8%). The cephalaspidean Gastropterum pacificum is the only 10 gymnosomes, and one nudibranch; these comprehends four known. California. Of those 11 were heteropods, 16 thecosomes, known member of its order to be considered as a semi- Figure 1. Golfo de California). Study area and sampling stations. a) GOLCA surveys; b) CGC surveys. Four of those surveys (March, May, September 2005 and March 2006) were named CGC (for Circulación en el Golfo de California) and the remaining three (November 2005, January and Agust, 2007) were called GOLCA (for Check List | Volume 7 | Issue 3 | 2011 338 Angulo-Campillo et al. | Holoplanktonic mollusks, Gulf of California, México with young “individuals” spending more time in the water columnplanktonic (Wrobel species, and a Millsresult 1998). of its being a benthic species Diego province. The hypothesis that the holoplanktonic ismollusk supported community for other could groups be for a exampleremnant asof awhen plausible the valid gymnosomes species (Spoel et al. 1997; Cummings Gulf of California was connected with the Pacific Ocean There are 122 valid shelled pteropodset al. species,2009,). andThese 66 northern portion of the Gulf of California and the adjacent groups have representatives in several habitats, such as explanation of the similitude between theet al fish. 2003). fauna in the thoseand Seapy found 2003;in polar Suárez-Morales waters (e.g. Limacina australis and Clione antartica). When comparing the number of species western North Pacific (Aceves-Medina When comparing the species richness of holoplanktonic Gymnosomata nine species), with the ones recorded mollusks with other marine regions (Table 2), differences duringrecorded this for studythe Eastern (Thecosomata Pacific (Thecosomata 21, Gymnosomata 32 species, 13), Inbetween contrast the with North relatively Pacific andrecent South new Atlantic, areas of due study to the of historic research background in such areas are clear. Diacavolinia longirostris,we collected moreGleba thancordata, the 50% Desmopterus of