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Biogeografia y biodiversidad de moluscos gastropodos de la plataforma y talud continental brasileno.

Biogeography and biodiversity of gastropod molluscs from the eastern Brazilian continental shelf and slope


Understanding the patterns of the geographic distribution of life is a very old issue in biology, and one that continues to be debated. In the sea, geographic patterns (e.g., in species assemblages and diversity) have been described for both shallow and deep-sea fauna (Rex, 1993; Rex et al., 1993; Clarke & Crame, 1997; Gray, 1998; Willig et al., 2003; Hillebrand, 2004).

Longitudinal and latitudinal barriers represented by the arrangement of land masses and oceans, by temperature gradients, and by hydrodynamic patterns and water properties divide the oceans into a series of biogeographic realms with their own characteristic species assemblages (Briggs, 1995; Longhurst, 1998). The sea surface temperature is supposed to be the main force limiting the latitudinal distribution of marine species. Therefore, biogeographic realms are not expected to be the same along a depth gradient. In general, the wider a species' vertical distributional range, the wider its geographical distribution (Harley et al., 2003). Eurybathic taxa (those with a broader vertical range) show a wider horizontal distribution than stenobathic taxa (those with a narrow vertical range) (Vinogradova, 1997). Due to the fact that deep-sea species are mainly stenobathic, abyssal and hadal fauna show higher levels of endemism (Vinogradova, 1997; Zezina, 1997). The bulk of shallow-sea fauna is also stenobathic but, according to Menzies et al. (1973), the fauna on the continental slope has a wider geographical distribution than that of any other vertical faunal zone.

Several authors have discussed zoogeographic and diversity patterns for Brazilian shallow waters based on benthic invertebrates (e.g., Briggs, 1974; Semenov, 1978; Kempf, 1979; Palacio, 1982; Floeter & SoaresGomes, 1999), but few have discussed biogeographic patterns of the neighbouring slope or abyssal zones (Allen & Sanders, 1996 is a good example for abyssal basins).

The effect of the latitudinal gradient is so strong on the species diversity of marine molluscs that it is also evident at the genus and family level (Roy et al., 1998; Crame, 2000) and recognized in fossil assemblages (Crame, 2002; Jablonski et al., 2006). However, in spite of the fact that molluscs are one of the earliest taxa used to investigate latitudinal trends in marine biodiversity, some doubts exist as to whether the latitudinal trends observed in the northern hemisphere also occur in the southern hemisphere (Crame, 2000; Valdovinos et al., 2003; Linse et al., 2006). Some results are conflicting. For example, the patterns found for Pacific Ocean molluscs in the southern hemisphere by Valdovinos et al. (2003) opposed those found by Fortes & Absalao (2004).

The present study aimed to investigate patterns in both the regional and depth distribution of gastropod molluscs, discussing aspects of slope and shelf diversity and provinciality, contributing to the discussion about the latitudinal diversity gradient in the southern hemisphere.


Study area

The study area comprised the slope and continental shelf between 18[degrees]-23[degrees]S and 38[degrees]-41[degrees]W, encompassing an area ranging from the Abrolhos reef bank, situated in the north of Doce River, to the offshore and nearshore region in the vicinity of the Paraiba do Sul River. The study area was divided into two regions: north (18[degrees]-19[degrees]S), up to 200 km-long, and south (21[degrees]23[degrees]S), where the shelf is narrow and shallow, ranging from 10 to 30 km in width (Fig. 1). The continental slope in both regions is narrow and steep (Emery &


Uchuoi, 1984). The oceanographic conditions consist of oligotrophic areas that are associated with the tropical waters of the Brazil Current (BC) and mesotrophic areas due to the seasonal upwelling of the cold, nutrientrich waters of the South Atlantic Central Water (SACW) south of the Doce River (20[degrees]S) (Valentin et al., 1987). Primary productivity varies from 0.3 g C [m.sup.-2] [d.sup.-1] to 1.1 g C [m.sup.-2] [d.sup.-1] (Gaeta et al., 1999) and the input of the Doce and Paraiba do Sul rivers is about 900 [m.sup.3] [s.sup.-1]. The grain-size distribution is not uniform in the area, varying with depth; shallower stations have coarse sediments and deeper stations have finer sediments. The clay and silt concentrations revealed a depth gradient as well, with higher concentrations occurring at deeper stations. Concentration of calcium carbonate exhibited a patchy distribution, with higher percentages in the western sector (Soares-Gomes et al., 1999).

Sampling design and data analysis

Data for this study were obtained in April 1995, during the Joint Oceanographic Project (JOPS-II/ Leg 8), on board the R/V Victor Hansen from Bremen University, Germany. Sampling was carried out at 41 stations, between the depths of 20 m and 1,330 m (Fig. 1 and Table 1). Molluscs were present in 37 of these 41 stations (23 stations in the shelf zone and 14 in the slope zone). The sediment was sampled in triplicate with a 0.1 [m.sup.2] van Veen grab and a 60 x 60 x 30 cm box-corer. Samples were standardized to an area of 0.1 m2 and 10 L of sediment volume. The macrozoobenthos was sieved out with a 0.5 mm mesh size, fixed in 70% ethanol, and sorted under a stereomicroscope for taxonomic identification.

The frequency of occurrence ([F.sub.o] = number of occurrences of a species at the shelf or slope stations / total number of shelf or slope stations) was calculated, and species were classified according to their value as constant ([F.sub.o] > 50%), common (10% [is less than or equal to] [F.sub.o] [is less than or equal to] 50%), or rare ([F.sub.o] < 10%). Species distribution over the shelf and slope was examined by plotting a histogram of the number of species against the number of stations occupied.

We used Estimates 6.0b1 software (Colwell, 1997) to determine whether the species were classified as "unique" (restricted to a single site), "duplicates" (occurring at exactly two sites), "singletons" (represented by a single individual), or "doubletons" (represented by only two individuals), following the terminology of Colwell & Coddington (1994).

To perform a species richness scale analysis, the total data set was divided into four regions according to their location in geographic areas (north and south) and bathymetric zones (shelf and slope): north shelf, south shelf, north slope, and south slope. Due to different sampling efforts, randomized species cumulatives curves were plotted using Primer 6.1.6 software. Thus, we were able to compare species richness among regions, where the y-axis is the cumulative number of species and the x-axis the station numbers (north shelf: 17, south shelf; 6, north slope: 5, south slope: 9). An area of 0.1 m2 was considered for each sampling station. According to Gray (2002), when sample sizes are different, this method is preferable to rarefaction curves as proposed by Sanders (1968). Species diversity was also estimated on a progressive spatial scale, according to Gray's terminology (2000): sample species richness ([SR.sub.S]) and species richness in large areas (north shelf, south shelf, north slope, south slope) ([SR.sub.L]). Together, the four regions comprised the total area species richness ([SR.sub.T]). In order to calculate the proportion by which a given region is richer than the average of samples within the total area, Whittaker's (1972) original beta diversity measure ([beta].sub.W] =([gamma]/[alpha]) - 1) was used, where [gamma] is the total number of species resulting from merging a number of individual samples and a is the average number of species per individual sample. Beta diversity was measured over sectors [[beta].sub.W] = ([SR.sub.L/mean] [SR.sub.S])] and total area [[beta].sub.W = ([SR.sub.T/mean] [SR.sub.S])] scales, where [sub.mean.[SR.sub.S] was the mean sample diversity.

The species' geographic and bathymetric distribution ranges were determined based on information available in the literature (Abbott, 1974; Merlano & Hegedus, 1994; Rios, 1994, among others) and in the Malacolog 3.1 electronic database (Rosenberg, 1993 Geographic boundaries were established based on the southwestern Atlantic biogeographic provinces (Tropical, Paulista, Patagonic, Malvinas) defined by Palacio (1982) using the endemism rate. For a better representation of the geographic distribution in the area, the species were grouped according to their occurrence in the north and south regions. The shelf samples provided 211 species: 91 from the south region, 179 from the north region, and 59 from both regions. From the slope samples, 96 species were used: 72 from the south region, 55 from the north, and 31 from both regions. Depending on the bathymetric distribution, species were designated according to the zonation proposed by Zezina (1997) and Vinogradova (1997) as: shallow species (0-200 m depth), bathyal species (200-3,000 m), and abyssal species (3,000-6,000 m). Species found in both the shelf and bathyal zones were designated eurybathic.

We excluded pelagic species and juveniles (12.25% of the total number of species) from the analyses due, not only to the difficulties in identifying juveniles, but also to the aim of the present study, which is to analyze only benthic species. Only individuals identified to the species level or ones that could unequivocally be labelled as species were used in the analysis.


Spatial distribution of species

A total of 9,845 specimens, 404 species and morphotypes (including empty shells), 189 genera, and 73 families were collected over the entire study area. A set of 243 species, 93 genera, and 28 families was found exclusively in the shelf zone, whereas 137 species, 43 genera, and 14 families were exclusive to the slope zone. Only 24 species (6%), 20 genera (10.6%), and 16 families (22%) occurred in both zones (Appendix 1 and 2).

Species distribution over the shelf shows that about half the species (130) were restricted to one station and none occurred at all stations. The same pattern was found for the slope, with 110 species restricted to one single site. Considering the shelf and slope, about 3% of the species occurred at more than 50% of all sites (Fig. 2). On the shelf, 2% were constant, 32% common, and 66% rare species. On the slope, the corresponding figures were 1%, 42%, and 57%.

In the whole area, 48% of the species were unique and 18% were duplicates. Singletons and doubletons represented 34% and 13%, correspondingly. The north shelf featured 26% unique species and 17% singletons, and the north slope had 12% unique species and 5% singletons (Table 2).


Diversity gradients

The cumulative dominance on the shelf was similar for both north and south regions. On the slope, there was a great difference in cumulative dominance between the two regions, with the north presenting the highest evenness (Fig. 3). Comparing the cumulative dominance along a vertical gradient, the evenness of the north slope was almost 10% higher than that of the north shelf, whereas the evenness of the south shelf was 40% higher than that of the south slope (Fig. 3).

The estimated species richness on the north shelf was higher than on the south shelf. However, when the sampling area was standardized to 0.6 [m.sup.2] (considering the area of a station as 0.1 [m.sup.2]), the richness was similar on both shelves (Fig. 4). The south slope displayed a higher total cumulative number of species per area than did the north slope. Conversely, when standardizing the sampling area to 0.5 [m.sup.2], richness was higher on the north slope. In the north, species richness was 0.5 [m.sup.2] higher in the slope zone than in the shelf zone, whereas the opposite pattern was observed in the south (Fig. 4).

In terms of diversity scales, the Alpha diversity (SRS) values found in the study area ranged from 2 to 84 species. The mean alpha diversity was highest on the north shelf, where 84 species were found at one station, followed by the south shelf, where richness ranged from 15 to 43 species within stations. The highest value of beta diversity ([SR.sub.L/mean] [SR.sub.S]) was found on the north shelf (6.66) and the lowest on the north slope (3.22). [beta].sub.W] values almost doubled on the largest scale ([SR.sub.T/mean] [SR.sub.S]) compared to the highest value found on the large area scale (Table 2).

Biogeographic distribution

For the continental shelf samples, 211 species and 89 genera were characterized according to their occurrence in the southwestern Atlantic zoogeographic provinces: 91 species from the south, 179 from the north, and 59 species from both regions. For the continental slope samples, 96 species and 52 genera were characterized: 72 species from the south, 55 from the north, and 31 from both regions.

In terms of the geographical distribution of taxa, the number of genera with a wide distributional range (occurring in more than three provinces) was lower than the genera with narrower distributions for both shelf and slope stations. However, considering the genera that occurred in both zones, the number of wide-range distributions was higher than the narrow-range ones (Table 3).

At the shelf stations, the number of species co-occurring in both Tropical and Paulista (Tropical-Paulista species) provinces was greater than the number of Tropical species occurring in both regions. In addition, the number of Tropical, Paulista, and Tropical-Paulista species decreased and the number of wide-distribution eurythermic species increased in the southwestern Atlantic provinces (Tropical-Paulista-Patagonic species) towards the south (Fig. 5). At the slope stations, Tropical species were the majority in both regions. The number of Tropical, Paulista, Tropical-Paulista, Tropical-Paulista-Patagonic, and subtropical Paulista-Patagonic species increased towards the south. The number of endemic species was higher in the north for both shelf and slope stations. In addition, a greater number of Tropical endemic species was present at the slope stations in both the south and north, and the shelf stations displayed the highest occurrence of Paulista endemic species. The number of species occurring in all Western Atlantic Provinces was greater on the south shelf (Table 4). Furthermore, shelf stations showed a higher number of eurybathic species (with a wide bathymetrical range) than did slope stations (Table 5).



The shelf-slope transition zone is known to have a high species turnover rate (Rex et al., 1977). Moreover, species typically found on continental shelves and species from continental slope zones can coexist there, leading to higher species richness. However, evidence from studies done on the Brazilian continental slope showed that the depth where this species turnover begins is variable. In this study, we found high species turnover at station 16 (300 m depth), where some deep-sea species, such as Alvania xantias (Watson, 1885), Brookula spinulata (Absalao, Miyaji & Pimenta, 2001), and Solariella lubrica (Dall, 1881) showed a high dominance. Miyaji (2001) found a rough change, with 8% of sampled species occurring exclusively at depths greater than 400 m, whereas Sumida & Pires-Vanin (1997) found a different community from shallow areas occurring between 320 m and 500 m depth.


Analyzing the vertical distribution of species found in this study (Table 2), we observed the occurrence of shallow-water and eurybathic species (shallow-bathyal, distributions) at the slope stations. This pattern might constitute evidence of the slope's capacity to allow the co-existence of shallow and deep-water species.

The depth gradient differed between the north and south regions: the north shelf showed the highest local, regional, and between-habitat species richness, whereas the south slope had the highest species richness, with values close to the shelf ones. Along local gradients, the general pattern observed is that species richness changes with depth, increasing from ca. 200 m to 1500-2500 m or more, and then decreasing towards the abyssal plain (Rex et al., 1993, 2000; Gray, 2002). Nevertheless, those unimodal patterns do not shallow-bathyal-abyssal, bathyal-abyssal appear to be universal (Rex et al., 1997; Stuart et al., 2001), showing that the change in species richness is not related to depth itself (Gray, 2002).

The highest species richness values observed on the north shelf could be a result of the fact that the highest number of samples were taken in this area, but also of the greater environmental heterogeneity in the area. Larger areas potentially support more species richness on a variety of scales and harbor higher overall richness, whereas the number of habitats also increases, as well as the number of biomes, or of biogeographic provinces within them (Rosenzweig, 1995; Willig et al., 2003). On the north shelf, species can find a wide continental shelf (200 km) featuring a high variety of bottom types, as well as the presence of corals and calcareous algae bank habitats. On the other hand, the south region is characterized by a narrow shelf area (10-30 km) and a less heterogeneous bottom (Soares-Gomes et al., 1999). Additionally, because of the constant presence of the Brazil Current, the north region is oligotrophic, which may limit the abundance of species. Conversely, the south region is considered to be mesotrophic due to the seasonal upwelling of cold, nutrient-rich, SACW waters (Gaeta et al., 1999), leading to higher richness.

In addition to the above-mentioned patterns, environmental features also changed with depth. Both north and south slopes are narrow and steep, with more homogeneous bottoms that are dominated by silt fractions and a higher concentration of organic carbon.


The study area is included in a wide transition zone known as the Paulista province (Palacio, 1982). The present study found a lower number of tropical species and a higher number of subtropical ones (species that are common to the Paulista and Patagonic provinces) towards the south. Moreover, a great presence of species common to both the Tropical and Paulista provinces was observed over the entire area. Other studies carried out at more southerly latitudes on the Brazilian coast show the same distribution for molluscs (Mello, 1993; Miyaji, 1995) and polychaetes (Lana, 1987; Attolini, 1997). Furthermore, on the Uruguayan coast (Scarabino, 2004), 16 among 182 gastropods were the same as the species reported in this study (carried out in the Tropical and Paulista provinces). The presence of species that are considered to be endemic to the Paulista Province (i.e., Anachis fenelli Radwin, 1968; Favartia varimutabilis Houart, 1991; Olivella defiorei Klappenbach, 1964) and subtropical species from the Patagonic Province in the north region (Tropical Province) corroborate the notion of a broader transition zone between tropical and temperate waters (Van nucci, 1964; Lana, 1987; Miyaji, 1995; Floeter & Soares-Gomes, 1999).

The disappearance of some tropical species towards the south suggests that the southernmost limit of the Tropical Province is located close to 21[degrees]S, according to the results found for gastropods (Floeter & Soares-Gomes, 1999); cirripeds (Young, 1995), and polychaetes (Lana, 1987). Nevertheless, the location of that limit remains uncertain (Absalao, 1989; Mello, 1993; Briggs, 1995). Recently, Joyeux et al. (2001) and Floeter et al. (2008) found that, for tropical reef fishes, the southern limit is 28[degrees]S.

Many studies have demonstrated that the boundaries of shallow-water faunal distribution are correlated to water masses boundaries (Stevenson et al., 1998; Culver & Buzas, 2000). The presence of species with tropical affinities over the shelf area could be explained by the predominance of the warm and saline water mass of the Brazil Current (BC) (Absalao, 1989; Miyaji, 1995, 2001) that flows southwards (parallel to the shelf break) to 35[degrees]S (Emilsson, 1961). In that region, the BC mixes with the cold and less saline water mass of the Malvina Current and the water characteristics become markedly subtropical, with salinity and temperature ranging between 36-35 and 20[degrees]-10[degrees]C, respectively (Emilsson, 1961). This fact influences the occurrence of cold-water affinity species (Semenov & Berman, 1977; Palacio, 1982).

However, the most significant factor for the maintenance of cold-water species, as well as of eurybathic species in the shelf zone, particularly in the north region, might be the penetration of the South Atlantic Central Water (SACW) into the continental shelf regions. This water mass acts as a vehicle for larval dispersal from cold, deeper regions to warm, shallower areas (Absalao, 1989; Miyaji, 1995, 2001), and extends northwards to Espirito Santo State (Gaeta et al., 1999).

Important changes occur in the benthic faunal structure within the large vertical interval of the bathyal zone. The most obvious difference between shallow and deep-bottoms is the reduction in the number of latitudinal or climatic belts, both in terms of biomass and of faunal structures (Zezina, 1997). As there is a simplification in the water mass structure of the continental slope floor region, a reduction in the number of faunal provinces is to be expected (Semenov & Berman, 1977; Zezina, 1997; Culver & Buzas, 2000). Culver & Buzas (2000) found that the differences in benthic foraminifera fauna between shallow (< 200 m) and deep water (> 200 m) provinces at the same latitude were greater than between adjacent shallow water provinces.

As expected, species occurring in the shelf zone were very distinct from those in the slope area, with only 24 (out of 315) species shared between the two zones. When the latitudinal distribution of slope species is analyzed, the pattern is similar to the shelf species distribution. However, the number of Tropical and Tropical-Paulista species increased in the south region.

Studies on geographical distributions of deep-sea species have shown a greater number of species with wider horizontal ranges (Vinogradova, 1997; Zezina, 1997). However, the present study found few species with wide range distributions towards the slope stations. Similar results were observed for the geographic distribution of genera. The restricted-range genera (1 to 2 provinces) were represented by six more genera than the wide-range ones (> 2 provinces). It is, however, possible that the lower number of samples for the slope region (14 stations vs. 23 in the shelf zone) might induce such contradictory results. It is expected that enhanced sampling efforts will not only tend to increase the more sparsely distributed species, but also the number of "rare" endemic species (Allen & Sanders, 1996).

Comparing the species found in the present study area (18[degrees]-23[degrees]S) with their incidence in other geographical regions studied by others authors along the Brazilian continental slope (Merlano & Hegedus, 1994; Sumida & Pires-Vanin, 1997; Miyaji, 2001; Scarabino, 2004) revealed some shared species. Nineteen species were shared between the present study and works done on the northeast region (11.37%), from a total of 167 species found. Among those, the most dominant species were Brookula conica (Watson, 1985), Anatoma aedonia (Watson, 1886), Benthonella tenella (Jeffreys, 1883), and Alvania xantias (Watson, 1885). The southeast region shared 10 (7.57%) of a total of 132 species, with the dominant species being Brookula pfefferi A.W.B. Powell, 1951; Seguenzia hapala Woodring, 1928; Nannodiella vespuciana (Orbigny, 1842); and Solariella lubrica (Dall, 1881). Finally, the south region shared four (3.15%) of a total of 127 species; the most dominant species were Ancilla dimidiata (Sowerby, 1850); Basilissa alta (Watson, 1886); Pyrunculus ovatus (Jeffreys, 1870); and Puncturella granulata (Seguenza, 1863). As Allen & Sanders (1996) found for the zoogeographic distribution of protobranch bivalves through inter-basin comparisons on the percentage of shared species, the species number is higher between adjacent basins. Moreover, the majority of shared species are those from the Tropical Province and from both Tropical and Paulista Provinces. Analyses of the biogeographic distribution of bathyal species indicated a transitional pattern, as suggested for the shelf zone. However, the higher number of eurythermic species with tropical affinities found at the slope stations could be an indication that the limit of tropical bathyal species distribution is wider than that of tropical shelf boundaries.

Zezina (1997) proposed biogeographic schemes for the bathyal zone based on a recent brachiopod distribution, which is very similar to the results found in the present study for gastropods from the continental slope. This scheme proposed, for depths greater than 700 m in the northeast and central Brazilian bathyal zone (similar to the schemes for shallow-water fauna in the southwestern Atlantic), a sub-area named the Atlantic-Central American (divided into Caribbean and Brazilian provinces) and the south Brazilian-Uruguayan subtropical area in the southeast and south bathyal zones. Also, for recent brachiopods living below 700 m, Zezina (1997) defined only one area for the entire southwestern Atlantic Ocean: the Amphi-Atlantic Bathyal area within the central Atlantic Province.

A great species turnover rate was observed between the shelf and slope. An analysis of the gastropod species distribution revealed a similar pattern of regional distribution in shelf and slope zones and a great difference between shallow and deep-water faunas. Although the present analysis of biogeographic distribution patterns confirmed the existence of a transitional zone from tropical to subtropical waters in the case of the slope zone, the sampling effort done on the southeastern Atlantic slope is still too little and those results should be viewed with caution.

Appendix 1. Taxonomic list of species from the continental shelf (25-200 m depth).

Apendice 1. Lista taxonomica de especies de la plataforma continental (25-200 m de profundidad).

Family Scissurellidae Gray, 1847

Scissurella sp. Anatoma aedonia Watson, 1886 Sinezona brasiliensis Mattar, 1987

Family Fissurellidae Fleming, 1822

Diodora jaumei Aguayo & Rehder, 1936) Diodora meta (Ihering, 1927) Diodora mirifica Metivier, 1972 Diodora sayi (Dall, 1899) Diodora sp. Emarginula "aff." phrixodes Dall, 1927 Emarginula pumila (A. Adams, 1851) Emarginula tuberculosa Libassi,1859 Lucapinella limatula (Reeve, 1850) Puncturella antillana Farfante, 1947 Puncturella granulata Seguenza, 1863

Family Acmaeidae Carpenter, 1857 Colisella sp.

Family Trochidae Rafinesque, 1815

Calliostoma echinatum Dall, 1881 Calliostoma gemmosum (Reeve, 1842) Calliostoma sp. Calliostoma vinosum Quinn, 1992 Lamellitrochus carinatus Quinn, 1991 Lamellitrochus lamellosus Verrill & Smith, 1880 Lamellitrochus sp. Mirachelus clinocnemus Quinn, 1979 Solariella staminea Quinn, 1992

Family Skeneidae Thiele, 1929

Cyclostremiscus caraboboensis Weisbord, 1962 Cyclostremiscus ornatus (Olsson & McGinty, 1958) Cyclostremiscus pentagonus (Gabb, 1863) Haplocochlias "aff." swifti Vanatta, 1913 Parviturbo rehderi Pilsbry & McGinty, 1945 Parviturbo weberi Pilsbry & McGinty, 1945

Family Turbinidae Rafinesque, 1815

Arene bairdii (Dall, 1889) Arene brasiliana (Dall, 1927) Arene microforis (Dall, 1889) Arene variabilis (Dall, 1889) Arene venusta (Woodring, 1928) Astraea latispina (Philippi, 1844) Turbo sp.

Family Tricollidae Robertson, 1958

Gabrielona sulcifera Robertson, 1973 Tricolia "aff." (C.B. Adams, 1850) Tricolia bella (M. Smith, 1937)

Family Seguenziidae Verrill, 1884

Ancistrobasis costulata (Wattson, 1879)

Family Neritopsidae Gray, 1847

Smaragdia viridis (Linnaeus, 1785)

Family Phenacolepadidae Thiele, 1929

Phenacolepas hamillei (Fisher, 1857)

Family Rissoidea Gray, 1847

Alvania valeriae Absalao, 1993 Alvania aberrans (C.B. Adams, 1850) Alvania auberiana (Orbigny, 1842) Alvania sp. Benthonella tenella (Jeffreys, 1883) Ceratia rustica (Watson, 1885) Folinia bermudezi (Aguayo & Rehder, 1936) Rissoina cancellata (Philippi, 1847) Rissoina decussata Montago, 1803 Rissoina fenestrata Schwartz, 1860 Rissoina princeps (C. B. Adams, 1850) Rissoina sp.

Family Barleeidae Gray, 1857

Amphithalamus vallei Aguayo & Jaume, 1947 Barleeia rubrooperculata (Castellanus, 1972) Caelatura barcellosi Absalao & Rios, 1995 Caelatura sp.

Family Assimineidae H. & A. Adams, 1856

Assiminea succinea (Pfeiffer, 1840) Assiminea sp.

Family Caecidae Gray, 1850

Caecum brasilicum Folin, 1874 Caecum butoti DeYong & Coomans, 1988 Caecum cornucopiae (Carpenter, 1858) Caecum floridanum Stimpson, 1851 Caecum irregulare Stimpson, 1851 Caecum meioceras Carpenter, 1858 Caecum sp.

Family Vitrinellidae Bush, 1897

Circulus orbignyi (Fischer, 1857) Solariorbis "aff." shumoi (Vanatta, 1913) Solariorbis infracarinatus Gabb, 1881 Solariorbis mooreana (Vanatta, 1904) Teinostoma cocolitoris Pilsbry & McGinty, 1945 Vitrinella cupidinensis Altena, 1966

Family Modulidae Fisher, 1884

Modulus carchedeonius (Lamarck, 1822)

Family Cerithiidae Fleming, 1822

Bittium sp. Bittium varium (Pfeiffer, 1840) Cerithium litteratum (Born, 1778)

Family Litiopidae Gray, 1847

Alaba incerta (Orbigny, 1842)

Family Diastomatidae Cossmann, 1893

Finella dubia (Orbigny, 1842)

Family Fossaridae Troschel, 1861

Megalomphalus troubei (Bavay, 1908)

Family Turritellidae Clarke-Woodward, 1851

Turritella exoleta (Linnaeus, 1758) Turritella hookeri Reeve,1849 Turritella sp.

Family Calyptraeidae Lamarck, 1809 Calyptraea centralis (Conrad, 1841) Calyptraea sp. Crucibulum auricula (Guimelin, 1791) Crucibulum striatum (Say, 1824)

Family Xenophoridae Troschell, 1852

Xenophora conchyliophora (Born, 1780)

Family Cypraeidae Rafinesque, 1815

Cypraea sp.

Family Triviidae Troschei, 1863

Trivia candidula (Gaskoin, 1836) Trivia nix Schilder, 1922 Trivia occidentalis Schilder, 1922 Trivia pediculus (Linnaeus, 1758) Trivia sp. Trivia suffusa (Gray, 1832)

Family Naticidae Forbes, 1838

Natica pusilla Say, 1822 Natica sulcata (Born, 1778) Sigatica semisulcata (Gray, 1839)

Family Cerithiopsidae H. & A. Adams, 1853

Cerithiopsis greenii (C.B. Adams, 1839) Cerithiopsis latum (C.B. Adams, 1850) Cerithiopsis sp. Seila adamsi (H. Lea, 1845)

Family Triphoridae Gray, 1847

Metaxia exilis (C.B. Adams, 1850) Triphora decorata (C.B. Adams, 1850) Triphora melanura (C.B. Adams, 1850) Triphora ornata (Deshayes, 1823) Triphora turristhomae (Holten, 1802)

Family Epitoniidae S.S. Berry, 1910

Amaea retifera Dall, 1889 Epitonium "aff." multistriatum (Say, 1826) Epitonium sp.

Family Aclididae G.O. Sars, 1878

Graphis sp. (Synonym: Aclis Loven, 1846)

Family Eulimidae Risso, 1826

Eulima auricincta Abbott, 1959 Eulima bifasciata (Orbigny, 1842) Eulima hypsela (Verril & Bush, 1900) Melanella arcuata (C.B. Adams, 1850) Scalenostoma sp.

Family Muricidae Rafinesque, 1815

Aspella castor Radwin & D'Attilio, 1976 Attiliosa sp. Attiliosa striatoides (E. Vokes, 1980) Chicoreus tenuivaricosus (Dautzenberg, 1927) Dermomurex leali Houart, 1991 Dermomurex sp. Favartia varimutabilis Houart, 1991 Murexiella glypta (M. Smith, 1938) Murexiella sp. Muricopsis sp. Typhis riosi Bertsch & D'Attilio, 1980

Family Buccinidae Rafinesque, 1815

Engina sp. Engina turbinella (Kiener, 1835) Pisania bernardoi P. M. Costa & Gomes, 1998

Family Columbellidae Swainson, 1840

Aesopus metcalfei (Reeve, 1858) Aesopus sp. Aesopus stearnsi (Tryon, 1883) Amphissa cancellata (Castellanos, 1982) Amphissa sp. Anachis carloslirai P.M. Costa, 1997 Anachis fenneli Radwin, 1968 Anachis isabellei (Orbigny, 1841) Anachis obesa (C.B. Adams, 1845) Mitrella "aff." lunata (Say, 1826) Mitrella albovittata Lopes, Coelho & Cardoso, 1965 Mitrella sp. 2 Nassarina minor (C.B. Adams, 1845)

Family Nassariidae Iredale, 1916

Nassarius albus (Say, 1826)

Family Fasciolariidae Gray, 1853

Fusinus brasiliensis (Grabau, 1904) Fusinus sp. Latirus devyanae Rios, P.M. Costa & Calvo, 1994 Latirus sp.

Family Olividae Latreille, 1825

Ancilla dimidiata (Sowerby, 1850) Oliva circinata Marrat, 1870 Olivancillaria urceus (Roding, 1798) Olivella defiorei Klappenbach, 1964 Olivella minuta (Link, 1807) Olivella puelcha (Duclos, 1840) Olivella sp.1 Olivella watermani (McGinty, 1940)

Family Marginellidae Fleming, 1828

Dentimargo lasallei Talawera & Princz, 1985 Eratoidea scalaris (Jousseaume, 1875) Eratoidea sp. Persicula "aff." sagittata (Hinds, 1844)

Family Mitridae Swainson, 1831

Mitra staminea A. Adams, 1853 Granulina clandestinella Bavay, 1908/1913 Granula lavalleana Orbigny, 1842

Family Mitrinae Swainson, 1831

Subcancilla candida (Reeve, 1845)

Family Costellariidae MacDonald, 1860

Vexilum exiguum (C.B. Adams, 1845) Vexilum hendersoni (Dall, 1927) Vexilum lixa Petuchi, 1979 Vexilum sp.

Family Cancellariidae Forbes & Hanley, 1853

Cancellaria petuchi Harasewych, Petit & Verhecken, 1992 Tritonoharpa lanceolata (Menke, 1828) Tritonoharpa leali Harasewych, Petit & Verhecken, 1992

Family Conidae Rafinesque, 1815

Conus jaspideus Guimelin, 1791 Conus mindanus Hwass, 1792

Family Turridae Swainson, 1840

Acmaturris brisis Woodring, 1928 Bellaspira sp. Benthomangelia macra (Watson, 1881) Crassispira cubana Melvill, 1923 Crassispira fuscescens (Reeve, 1843) Crassispira sp. Driliola sp. Drilliola comatotropis (Dall, 1881) Eucyclotoma stegeri (McGuinty, 1955) Fenimorea sp. Glyphostoma sp. Ithycythara pentagonalis (Reeve, 1845) Ithycythara sp. Kurtziella dorvillae (Reeve, 1845) Leptadrillia cookei (E.A. Smith, 1888) Lioglyphostoma jousseaumei (Dautzenberg, 1900) Mangelia barbarae (Lyons, 1972) Mangelia biconica (Dall, 1850) Mangelia rugurima (Dall, 1889) Mangelia sp. Mitrolumna biplicata (Dall, 1889) Nannodiella vespuciana (Orbigny, 1842) Neodrillia sp. Pilsbryspira sp. Polystira formosissima (E.A. Smith, 1915) Polystira sp. Pyrgocythara candidissima (C.B. Adams, 1845) Pyrgocythara guarani (Orbigny) Pyrgospira sp. Splendrillia carolinae (Bartsch, 1934) Splendrillia lissotropis (Dall, 1881) Splendrillia sp. Tenaturris fulgens (E.A. Smith, 1888) Tenaturris gemma (E.A. Smith, 1884) Tenaturris sp. Veprecula morra (Dall, 1881) Veprecula sp.

Family Terebridae Morch, 1852

Terebra "aff." duellojuradoi Carcelles, 1953

Family Architectonicidae Gray, 1840

Architectonica nobilis Roding, 1798 Heliacus bissulcatus (Orbigny, 1845)

Family Mathildidae Dall, 1889

Mathilda barbadensis Dall, 1881 Mathilda sp.

Family Pyramidellidae Gray, 1840

Chrysallida jadisi Olsson & McGuinty, 1958 Chrysallida sp. 1 Chrysallida toroensis (Olsson & McGuinty, 1958) Eulimastoma canaliculatum (C.B. Adams, 1850) Eulimastoma didyma (Verrill & Bush, 1900) Eulimastoma sp. Eulimastoma weberi (Morrison, 1965) Fargoa bushiana Bartsch,1909 Miralda havanensis (Pilsbry & Aguayo, 1933) Odostomia canaliculata C.B. Adams, 1850 Odostomia laevigata (Orbigny, 1842) Odostomia ovuloide C.B. Adams, 1850 Odostomia seminuda (C.B. Adams, 1837) Peristichia agria Dall, 1889 Pyramidella crenulata (Holmes, 1859) Pyramidella sp. Sayella crosseana (Dall, 1885) Turbonilla "aff." coomansi van Aartsen, 1994 Turbonilla arnoldoi Jong & Coomans, 1988 Turbonilla iheringi Clessin, 1900

Family Amathinidae Ponder, 1988

Iselica anomala (C.B. Adams, 1850)

Family Acteonidae Orbigny, 1842

Acteon pelecais Marcus, 1981

"Acteon" vagabundus (Mabille & Rochebrune, 1885)

Family Cylichnidae H. & A. Adams, 1854

Acteocina bidentata (Orbigny, 1841) Acteocina bullata (Kiener, 1834) Acteocina candei (Orbigny, 1842) Acteocina inconspicua Olsson & McGinty, 1958 Acteocina lepta Woodring, 1928 Acteocina sp. Cylichna discus Watson, 1883 Cylichna verrillii Dall, 1889 Cylichna sp. Scaphander darius Marcus, 1967

Family Hamineidae Pilsbry, 1895

Atys guildingi (Sowerby, 1869) Atys mandrewii E.A. Smith, 1872 Atys riiseana (Morch, 1875) Atys sandersoni Dall, 1881 Haminoea elegans (Gray, 1825)

Family Retusidae Thiele, 1926

Pyrunculus caelatus (Bush, 1885) Volvulella paupercula (Watson, 1883) Volvulella persimilis (Morch, 1875) Volvulella recta (Morch, 1875) Volvulella sp. Volvulella texasiana Harry, 1967

Family Siphonariidae Gray, 1840

Williamia krebsi (Morch, 1877)

Appendix 2. Taxonomic List of species from the Continental Slope (300-1330 m depth).

Apendice 2. Lista taxonomica de especies de la plataforma continental (300-1330 m de profundidad).

Family Scissurellidae Gray, 1847

Anatoma aedonia (Watson, 1886)

Family Fissurellidae Fleming, 1822

Puncturella antillana Farfante, 1947 Puncturella granulata Seguenza, 1863 Puncturella sp.

Family Cocculinidae Dall, 1882

Cocculina beanii Dall, 1882

Family Trochidae Rafinesque, 1815

Calliostoma "aff." coronatum Quinn, 1992 Euchelus sp. Basilissa alta Watson, 1879 Basilissa sp. Calliotropis actinophora (Dall, 1890) Calliotropis "aff." calatha (Dall, 1927) Calliotropis sp. Echinogurges "aff." clavatus (Watson, 1879) Echinogurges clavatus (Watson, 1879) Echinogurges sp. Echinogurges sp. 1 Echinogurges sp. 2 Echinogurges sp. 3 Microgaza sp. Mirachelus clinocnemus Quinn, 1979 Solariella lubrica Dall, 1881 Solariella sp. 1 Solariella sp. 2 Tegula sp.

Family Cyclostrematidae Fisher, 1885

Brookula conica (Watson, 1885) Brookula pfefferi A.W.B. Powell, 1951 Brookula sp. Brookula spinulata Absalao, Miyaji & Pimenta, 2001 Granigyra n. sp.

Family Turbinidae Rafinesque, 1815

Homalopoma boffi Marini, 1975

Family Tricoliidae Robertson, 1958

Tricolia aff.inis (C.B. Adams, 1850)

Family Seguenziidae Verrill, 1884

Ancistrobasis costulata (Watson, 1879) Hadroconus altus (Watson, 1879) Seguenzia hapala Woodring, 1928 Seguenzia sp. 1 Seguenzia sp. 2

Family Rissoidae Gray, 1847

Alvania auberiana faberi Jong & Coomans, 1988 Alvania xantias (Watson, 1885) Benthonella sp. Benthonella tenella (Jeffreys, 1883)

Family Barleeidae Gray, 1857

Barleeia sp.

Family Vitrinellidae Bush, 1897

Teinostoma "aff." obtectum Pils. & Mcg., 1945 Teinostoma "aff." reclusa Dall, 1889

Family Diastomatidae Cossmann, 1893

"Finella" mamillatum (Watson, 1880)

Family Vanikoridae Gray, 1840

Vanikoro oxychone Morch, 1877

Family Trichotropididae Gray, 1850

Lyocyclus pernambucensis (Watson, 1885)

Family Cypraeidae Rafinesque, 1815

Cypraea cinerea Gmelin, 1791

Family Naticidae Forbes, 1838

Polinices "aff." fringillus (Dall, 1881)

Family Bursidae Thiele, 1925

Bursa sp.

Family Epitoniidae S.S. Berry, 1910

Amaea retifera Dall, 1889 Cylindriscala watsoni (de Boury, 1911) Epitonium "aff." angulatum (Say, 1830) Epitonium sp.1 Epitonium sp.2 Opaliopsis aff. nitida (Verrill & Smith, 1885) Solutiscala formosissima de Boury, 1909

Family Janthinidae Leach, 1823

Recluzia rollandiana Petit, 1853

Family Eulimidae Philippi, 1853

Eulima sp. 1 Eulima sp. 2 Eulima sp. 3 Eulima sp. 4 Melanella "aff." arcuata (C.B. Adams, 1850) Melanella "aff." sarissa (Watson, 1883) Niso sp.

Family Velutininae Gray, 1840

Velutina sp. (?)

Family Muricidae Rafinesque, 1815

Chicoreus tenuivaricosus (Dautzenberg, 1927) Trophon sp.

Family Buccinidae Rafinesque, 1815

Belomitra pourtalesii (Dall, 1881) Belomitra sp. Kryptos tholoides (Watson, 1881)

Family Columbellidae Swainson, 1840

Amphissa cancellata (Castellanos, 1982) Anachis n. sp. 1 Anachis n. sp. 2

Family Olividae Latreille, 1825

Ancilla dimidiata (Sowerby, 1850) Olivella amblia Watson, 1882 Olivella (divina) n.sp.1

Family Mitrinae Swainson, 1831

Mitra sp.

Family Cancellariidae Forbes & Hanley, 1853

Brocchinia "aff." pustulosa Verhecken, 1991

Family Turridae Swainson, 1840

Gymnobela sp. Bathytoma "aff." mitrella Dall, 1881 Benthomangelia macra (Watson, 1881) Compsodrillia sp. Leptadrillia sp. Drillia "aff." premorra Dall, 1881 Drilliola comatotropis (Dall, 1881) Eubela limacina (Dall, 1881) Eucyclotoma sp. Fenimorea "aff." pagodula (Dall, 1889) Kurtziella "aff." serga (Dall, 1881) Kurtziella sp. Leucosyrinx verrillii (Dall, 1881) Leucosyrinx sp. Drilliola comatotropis (Dall, 1881) Nannodiella vespuciana (Orbigny, 1842) Pleurotomella "aff." benedicti Verrill & Smith, 1884 Pleurotomella "aff." blakeana (Dall, 1881) Pleurotomella "aff." cala (Watson, 1886) Pleurotomella "aff." ipara (Dall, 1881) Pleurotomella "aff." porcellana (Watson, 1886) Pleurotomella circumvoluta (Watson, 1881) Pleurotomella extensa (Dall, 1881) Pleurotomella perparva (Synonym: Philbertia perparva (Watson, 1881)) Pleurotomella sp. 1 Pleurotomella sp. 2 Pleurotomella sp. 3 Pleurotomella sp. 4 Pleurotomella sp. 5 Pleurotomella sp. 6 Pleurotomella sp. 7 Pleurotomella sp. 8 Spirotropis "aff." phaeacra (Watson, 1881) Spirotropis sp.

Family Mangeliinae Fischer, 1887

Mangelia comatotropis Dall, 1881

Family Pyramidellidae Gray, 1840

Cingulina babylonia (C.B. Adams, 1845) Eulimastoma sp. 1 Eulimastoma sp. 2 Eulimella smithii Verrill, 1882 Eulimella sp. 1 Eulimella sp. 2 Odostomia "aff." canaliculata C.B. Adams, 1850 Sayella crosseana (Dall, 1885) Turbonilla "aff." unilirata Bush, 1899 Turbonilla sp. 1 Turbonilla sp. 2 Turbonilla sp. 32 Turbonilla sp. 35

Family Acteonidae Orbigny, 1842

"Acteon" vagabundus (Mabille & Rochebrune, 1885) Acteon pelecais Marcus, 1981 Acteon perforatus Dall, 1881 Rictaxis sp.

Family Ringiculidae Philippi, 1853

Ringiculina nitida Verrill, 1874

Family Cylichnidae H. & A. Adams, 1854

Cylichna "aff." crispula Watson, 1883 Cylichna discus Watson, 1883 Cylichna verrillii Dall, 1889 Cylichna vortex Dall, 1881 Scaphander darius Marcus, 1967

Family Diaphanidae Odhner, 1914

Diaphana seguenzae (Watson, 1886)

Family Bullidae Rafinesque, 1815

Bulla "aff." abyssicola Dall, 1881 Bulla "aff." eburnea (Dall, 1881)

Family Hamineidae Pilsbry, 1895

Haminoea elegans (Gray, 1825) Haminoea petitii (Orbigny, 1842) Haminoea sp. Atys guildingi (Sowerby, 1869) Atys mandrewii E.A. Smith, 1872

Family Retusidae Thiele, 1926

Pyrunculus ovatus (Jeffreys, 1870) Volvulella persimilis (Morch, 1875)

DOI: 10.3856/vol37-issue2-fulltext-3


The authors are indebted to Dr. Bastian Knoppers for the invitation to join in the Joint Oceanographic Project II (JOPS-II), and to Drs. Ricardo Silva Absalao and Paulo Marcio Costa for helping with taxonomic identification. We also thank Dr. Sergio Floeter for some valuable suggestions that improved the manuscript and Carla Mendes for reviewing the English version.

Received: 8 July 2008; Accepted: 2 March 2009


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Gabriela Benkendorfer (1) & Abilio Soares-Gomes (1)

(1) Marine Biology Department, Universidade Federal Fluminense, P.O.Box 100.644, Niteroi, RJ, Brazil

Corresponding author: Abilio Soares-Gomes (
Table 1. Number of stations per area, location of areas, and depth
range per area.

Tabla 1. Numero de las estaciones por area, ubicacion de las areas
y variacion de la profundidad por area.

Area          No of      Latitude      Longitude     Depth
              stations   ([grados]S)   ([grados]W)   (m)

North shelf   17         18 - 19       38 - 39       22 - 90
South shelf   6          21 - 23       39 - 41       25 - 200
North slope   5          18 - 19       38 - 39       510 - 1330
South slope   9          21 - 23       39 - 41       300 - 1320

Table 2. Species richness (sample species richness (SRs) = alpha
diversity; mean alpha diversity (MeanSRS); large area species
richness (SRL); total area species richness (SRT), number of
individuals (n), and beta diversity for the large area and the
total area ([beta]W). Unique species are those restricted to a
single station; duplicates are species occurring at exactly two
stations; singletons are species represented by a single
individual; doubletons are species represented by only two
individuals. CI 95% confidence intervals.

Tabla 2. Riqueza de especies (sample species richness (SRs) =
diversidad alpha; diversidad alpha media (MeanSRs); riqueza de
especies para areas grandes (SRL); riqueza de especies por area
total (SRT), numero de individuos (n) y diversidad beta para
areas grandes y area total ([beta]W). Especies unicas son las
especies limitadas a una sola region; especies duplicadas son
las que se enconntraron en dos estaciones; singletons son
especies representadas para un solo individuo; double-tons son
especies representadas para solo dos individuos. CI 95%
intervalos de confianza.


Large Areas   Range        [sub.Mean][SR.sub.S][+ o -]CI    [SR.sub.L]

North Shelf   2 - 84       33.94[+ o -]11.7                 226
South Shelf   15 - 42      26.40[+ o -]11.7                 113
North Slope   8 - 40       28.16[+ o -]8.9                  85
South Slope   4 - 46       22.77[+ o -]10.8                 127

Total         2 - 84       29.27[+ o -]6.3 [SR.sub.T]       404

                           [beta]W =

Large Areas   n            ([SR.sub.L]/                     Unique
                           [sub.Mean][SR.sub.S])            (%)

North Shelf   5082         6.66                             26.35
South Shelf   1003         4.28                             20.68
North Slope   1014         3.02                             12.31
South Slope   2746         5.58                             21.18

Total         9845         [beta]W = ([SR.sub.T]/           48.52

Large Areas   Duplicates   Singletons                       Doubletons
              (%)          (%)                              (%)

North Shelf   10.83        17.48                            7.63
South Shelf   3.69         12.31                            3.20
North Slope   6.15         5.66                             4.43
South Slope   5.41         16.25                            3.94

Total         17.98        33.74                            13.30

Table 3. Biogeographical distribution of genera found only on the
shelf, only on the slope, and in both (shelf and slope) zones.

Tabla 3. Distribucion biogeografica de los generos encontrados solo
en la plataforma, solo en el talud y encontrados en ambas areas
(plataforma y talud).

Biogeographic distribution             Shelf   Slope   Shelf and Slope

Tropical                               20      18      4
Tropical-Paulista                      45      6       14
Tropical-Paulista-Patagonic            6       7       15
Tropical-Paulista-Patagonic-Malvina    13      11      17
Paulista-Patagonic                     1       0       0
Paulista-Patagonic-Malvina             0       0       1
Others                                 4       10      14

Others = Occurrence in the S.W. Atlantic and in other regions such as
E. Pacific, W. Africa, the Mediterranean, the Arctic.

Table 4. Biogeographical distribution of species in the
shelf and slope zones and in the north and south sectors.

Tabla 4. Distribucion biogeografica de las especies en
las areas de plataforma y talud, y en los sectores norte y

                     North Section

Biogeographical distribution    Shelf   Slope

Southwestern Atlantic           10      1
Endemic to Brazil               3       0
Endemic to Tropical Province    4       7
Endemic to Paulista Province    5       1
Others                          8       2

                     South Section

Biogeographical distribution    Shelf   Slope

Southwestern Atlantic           14      3
Endemic to Brazil               1       1
Endemic to Tropical Province    1       4
Endemic to Paulista Province    4       1
Others                          0       8

Table 5. Vertical distribution of species sampled at shelf
and slope stations based on the literature (Abbott, 1974;
Rosenberg, 1993; Rios, 1994; Merlano & Hegedus,

Tabla 5. Distribucion vertical de las especies muestreadas
en las estaciones de la plataforma y del talud, basada
en la literatura (Abbott, 1974; Rosenberg, 1993; Rios,
1994; Merlano & Hegedus, 1994).

Bathymetric zone          Shelf region   Slope region

Shallow (0-200 m)         149            22
Bathyal (200-3000 m)      2              42
Shallow-Bathyal           55             28
Shallow-Bathyal-Abyssal   1              1
Bathyal-Abyssal           0              2
Abyssal (> 3000 m)        0              0
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Title Annotation:Research Article
Author:Benkendorfer, Gabriela; Soares-Gomes, Abilio
Publication:Latin American Journal of Aquatic Research
Article Type:Report
Date:Jul 1, 2009
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