Guido Pastorino

No longer the pristine confines of the world ocean: a survey of exotic marine species in the southwestern Atlantic

We conducted a comprehensive survey of existing knowledge about exotic marine organisms introduced to the southwestern Atlantic Ocean, including coastal and shelf areas of Uruguay and Argentina. This domain is equivalent to the so-called Patagonian Shelf Large Marine Ecosystem, and corresponds to two biogeographic provinces: warm-temperate (Argentine Province) and cold temperate (Magellanic Province). The search included species that can be confidently categorized as introduced (31) and cryptogenic species (46). We present a comprehensive picture of recorded introductions (the first for this region) and some prominent ecological consequences. Most coastal ecosystems between the La Plata River estuary and central Patagonia have already been modified, or are expected to be so in the short term. Five recent, human-mediated biological invasions have already had a significant ecological impact. A barnacle (Balanus glandula) belt has developed on all rocky shores where none was present 30 years ago, a macro-fouler (Limnoperna fortunei) and a reef-builder (Ficopomatus enigmaticus) have strongly modified estuarine ecosystems, Pacific oyster (Crassostrea gigas) reefs are expanding in shallow bays at a fast rate, and kelp (Undaria pinnatifida) is rapidly modifying nearshore benthic communities along the coasts of central Patagonia. At this point, it is uncertain how many of the cordgrasses (Spartina spp.) found in coastal salt marshes correspond to exotic forms. Only exposed sandy beaches appear to be free from the pervasive ecological impact of invasion by exotic species. Poor knowledge of the regional biota makes it difficult to track invasions.

ON THE EGG MASSES, EGGS AND EMBRYOS OF NOTOCOCHLIS ISABELLEANA (D'ORBIGNY, 1840) (GASTROPODA: NATICIDAE) FROM NORTHERN PATAGONIA

Naticids are common predators in sandy bottoms of shallow waters around the world. Probably due to their infaunal habitat, they are hard to find alive, particularly in the Patagonian waters of Argentina. Nevertheless, their presence is confirmed by the typical predation boreholes that can be seen on their bivalve prey along the coast (e.g., Bromley, 1981; Carriker, 1981; Pastorino & Ivanov, 1996; Signorelli et al., 2006). These boreholes record information on predators without actually seeing them. Paleontologists have exploited this field, analyzing the behavior and producing models of predator-prey relationships in ancient and recent communities (Kabat, 1990, and citations herein). Studies on the spawn of naticids are scarce in modern literature, despite its common presence in sandy bottoms. The typical sand collars were recognized several decades ago as belonging to this family. Ankel (1930) and Thorson (1935, 1940, 1946), among others, described these characteristic egg masses from different areas around the world. An accurate account of the morphology of the collar and capsules, including the way the gastropod builds them, was described by Giglioli (1955) and Ziegelmeier (1961). An interesting approach was recently published by Huelsken et al. (2008), who reviewed the naticids from Giglio, an Italian island off the coast of Tuscany. They compared mitochondrial and nuclear gene fragments (COI, 16S, H3, 18S) from adults and embryos from the egg masses, leaving no doubt about the mother species of each egg mass. During the past few years, several papers were published in which egg capsules of various gastropods from the southwestern Atlantic were described (Pastorino & Penchaszadeh, 1999, 2002; Pastorino et al., 2007; reviewed in Gallardo & Penchaszadeh, 2001). However, there is no published information about naticids MALACOLOGIA, 2009, 51(2): 395−402

The Genus Sphenia Turton, 1822 (Bivalvia: Myidae) from Shallow Waters of Argentina

The genus Sphenia was first reported in southern South America by Pilsbry (1899), who described Sphenia hatcheri from shallow Patagonian waters. Later, castellanos (1965) published a short note with comments on the type material of this species, studied by the late J. J. Parodiz at the Academy of Natural Sciences of Philadelphia, USA. Finally, in her catalogue of marine mollusks from Buenos Aires province (1970: 279), castellanos mentioned Mar del Plata (38°S) as the farthest north distribution of this species. coan (1999) published a detailed review of the Pacific species of Sphenia, including some interesting data about two Atlantic species, S. hatcheri and S. fragilis. Scarabino & Zaffaroni (2004) and Scarabino et al. (2006) briefly reported and discussed the distribution of these species in Uruguayan waters. After an exhaustive study of the intertidal endolithic fauna of bivalves from Buenos Aires province, Argentina, new findings of specimens of Sphenia allow the reillustration and comparison of these species. In addition, new distributional ranges are provided.

A New Species of Laubiericoncha (Bivalvia: Vesicomyidae) from Deep Waters Off Argentina

ABSTRACT A new species of bivalve belonging to the family Vesicomyidae, Laubiericoncha puertodeseadoi, n. sp., is described. The material was collected during several cruises to the continental margin of Argentina on board of the R/V “Puerto Deseado”. The distribution of the genus Laubiericoncha is expanded to include the southwestern Atlantic Ocean. The description was done by using morphological characters of the shell and mantle cavity organs. All type material of congeneric species was examined and illustrated. Laubiericoncha puertodeseadoi, n. sp., is characterized by a compressed, subrectangular, elongated, inequilateral shell, with slightly prosogyrous umbo and a well-defined triangular pallial sinus, strong external ligament and ctenidia with two robust demibranchs, foot anteriorly projecting and fused siphons. This new species constitutes the first record of the genus Laubiericoncha living on the continental margin off Argentina.

A new species of tube-dwelling anemone (Cnidaria, Anthozoa, Ceriantharia, Ceriantheopsis) from the Warm Temperate South-western Atlantic

A new species of tube-dwelling anemone of the genus Ceriantheopsis (Cnidaria: Ceriantharia), Ceriantheopsis lineata sp. nov., is described and can be found in fine sand or mud in the sublittoral zone (0–200 m) from Argentina to Brazil (Warm Temperate South-western Atlantic). This new species is distinguished from its congeners by a number of features, however some characters (directive tentacles, line on tentacles and length of P2) allow a conclusive identification among the other Ceriantheopsis species.

A revision of the genus Savatieria Rochebrune & Mabille, 1885: an endemic group of buccinulid gastropods from the Magellanic region

The buccinulid genus Savatieria, endemic to the Magellanic region, is revised. New descriptions of shell, opercular and radular characters are provided for all valid taxa. Type material of all species ever included in Savatieria are illustrated, most of them for the first time. Five of those species are considered valid, but only three belong to the genus Savatieria: S. frigida Rochebrune & Mabille, 1885, S. coppingeri (Smith, 1881) and S. areolata Strebel, 1905. Savatieria bertrandi Melvill & Standen, 1914 is considered a probable synonym of S. areolata. ‘Savatieria’ meridionalis (Smith, 1881) and ‘S.’ chordata Castellanos, Rolán & Bartolotta, 1987 are excluded from Savatieria based on their radular, opercular and/or shell characters. The subgenus Lisosavatieria Castellanos & Fernández, 1975 is considered a synonym of Savatieria.

Figure 6 In Taxonomic Revision Of Brazilian Mactridae Lamarck, 1809 (Bivalvia: Cardiida)

FIGURE 6. Mactrotoma fragilis (Gmelin, 1791). A: original illustration of Chemnitz; B – C: Lutraria candida Lamarck, 1818, syntype (MNHN unnumbered), RV; D – F: Mactra braziliana, Lamarck, 1818, syntype (MNHN unnumbered), D: RV, E: LV; G – H: Mactra oblonga Say, 1822 syntype (ANSP 51418) LV and RV respectively; I – J: Mactra bilineata Deshayes in Reeve, 1854, Syntype, NHMUK unnumbered; K: Mactra anserina, original illustration of Guppy, 1875, scale bar = 1 cm.