Diego E. Gutiérrez Gregoric

FRESHWATER GASTROPODA FROM ARGENTINA: SPECIES RICHNESS, DISTRIBUTION PATTERNS, AND AN EVALUATION OF ENDANGERED SPECIES

Few studies have dealt with the geographic distribution of freshwater snails in Argentina. The objectives of this study were to: (1) determine species and family richness and diversity patterns; (2) verify if species richness behaves according to Rapoports rule; (3) identify and classify species according to their distributions; and (4) identify endangered species. A grid was applied to a map of Argentina, with each of 340 squares (SUs) representing 10,000 km2. A database of 3,376 records was analyzed. Of the 101 species belonging to ten families recorded in Argentina, four are introduced and 40 are endemic to Argentina. The Lithoglyphidae have the highest number of species (22). The highest species richness/SU was recorded in the Brazilic subregion at Salto Grande (32 species) on Uruguay River, and parts of the Río de la Plata (31). In this subregion the species richness values increase from west to east. The highest richness in the Chilean-Patagonian subregion was detected at San Carlos de Bariloche, Río Negro province (9), and the Chilinidae contained the largest number of species. In Argentina, the north-south decline species pattern could be explained through Rapoports rule. In Patagonia, the species richness gradients do not show significant west-east trends. Most of the native species of freshwater molluscs of restricted distribution can be considered endangered (about 45 species) but need further study.

The giant African snail, Achatina fulica (Gastropoda: Achatinidae): Using bioclimatic models to identify South American areas susceptible to invasion

Abstract. The best way to reduce problems related to invasive species is by preventing introductions into potentially susceptible areas. The purpose of this study was to create distribution models for the invasive gastropod Achatina fulica Bowdich, 1822 in South America in order to evaluate its potential geographic distribution and identify areas at potential risk. This mollusc, considered one of the 100 worlds worst invasive alien species, is the focus of intense concern due to its impact on agriculture, human health, and native fauna. We tested two commonly used ecological niche modeling methods: Genetic Algorithm for Rule-Set Prediction (GARP) and Maximum Entropy (MaxEnt). Models were run with occurrence points obtained from several sources, including the scientific literature, international databases, governmental reports and newspapers, WorldClim bioclimatic variables, and altitude. Models were evaluated with the threshold-independent Receiver Operating Characteristic (ROC) and Area Under the Curve (AUC). Both models had consistent performances with similar areas predicted as susceptible, including areas already affected and new potentially susceptible areas in both tropical and temperate regions of South America.

Invasion of the Argentinean Paranense Rainforest by the Giant African Snail Achatina fulica

Abstract: The tropical land snail Achatina fulica Bowdich, 1822, native to Africa, is reported for the first time in Argentina, in Puerto Iguazú City, Misiones Province. This city is surrounded by protected areas. Three randomly selected 1-m2 plots were marked off in private gardens and in the area surrounding an urban stream for snail sampling. The high snail density detected could have ecological, sanitary, and economic consequences which have already been documented in other countries.

Freshwater Gastropod Provinces from Argentina

ABSTRACT Diverse biogeographic regions have been proposed in Argentina using different approaches of biogeography and different criteria. However, none of these proposals has considered freshwater gastropods in estimating biodiversity values, although gastropods from continental waters have great ecological importance and are a useful group to characterize freshwater environments. For this reason, our aim is to define freshwater gastropod provinces and to compare them with the available information on biogeographic regions previously defined using other data sets. The gastropod database comprises approximately 4,000 georeferenced records from museum collections, bibliographic records, and collections of our research team. A similarity analysis among basins was carried out using the species as characters and applying Jaccards coefficient and UPGMA clustering with the MVSP program to obtain the resulting phenogram. Eight provinces were identified: I, Misionerean; II, Middle Paraná; III, Uruguay River; IV, Lower Paraná — Río de la Plata; V, Central; VI, Cuyo; VII, Northern Patagonia; and VIII, Southern Patagonia. Between Provinces V and VI lies a Transitional Zone that shows a higher faunal similarity with the Del Plata basin than with the Patagonian basins. The provinces with the highest diversity were I and IV (H = 1.92 and 1.89 respectively), while Province III shows the highest richness (S = 51) and quantity of endemic and vulnerable species. These provinces are the most densely populated in the country and therefore include the areas with the highest environmental degradation level.

First Records of Four Exotic Slugs in Argentina

Abstract: This paper reports for the first time the occurrence of four exotic terrestrial slug species in Argentina: Lehmannia valentiana (Férussac, 1823) (Limacidae), Deroceras invadens Reise et al. 2011 (Agriolimacidae), Arion intermedius Normand, 1852 (Arionidae) and Meghimatium pictum (Stolyczka, 1873) (Philomycidae). The study is based on specimens deposited in museums in Argentina. Both the morphologic characteristics and the mitochondrial cytochrome oxidase I gene sequences were used to identify the exotic species. Phylogenetic analyses were also carried out in order to explore the location of their origins. Lehmannia valentiana had the oldest records and has been widely distributed in Argentina. Deroceras invadens and A. intermedius were found to be restricted to the southern portion of the country. Meghimatium pictum was recorded in the northwest and northeast Argentina, and the DNA sequences analyzed from this species were more closely related to specimens from the west of the Strait of Taiwan. A determination of the origin of the other species was impossible because either the sequences analyzed grouped with samples from different geographical origins or only few sequences were available for comparison. In view of the invasive potential of these slug species, the present work provides new and potentially useful DNA sequence data obtained from morphologically-confirmed specimens. Information provided from these analyses should assist in making a rapid identification of these exotic slugs by nonspecialists and governmental authorities who are responsible for managing and controlling the presence of exotic species.

Population Studies of an Endemic Gastropod from Waterfall Environments

Abstract: Chilinidae is a family endemic to South America, ranging from the Tropic of Capricorn to Cape Horn and the Falkland Islands, and includes 32 species. However, there are few population studies on the Chilinidae. We study aspects of the ecology of an endemic species, Chilina megastoma Hylton Scott, 1958, from the Arrechea Falls in the Iguazú National Park, Argentina, such as density and individual annual growth trends. Nine samplings were carried out between December 2003 and December 2005, using two transects that crossed the waterfall. Individual annual growth rate was analyzed according to length, following von Bertalanffys model. Six cohorts were identified, some in the same climatic season but successive years (two in winter and two in summer). The winter and autumn cohorts reached 85% of their last whorl length in the first year. Compared to other families of gastropods from subtropical climates, these populations have several recruitment events per year, but never in winter.

Freshwater gastropods diversity hotspots: three new species from the Uruguay River (South America).

Background: The Atlantic Forest is globally one of the priority ecoregions for biodiversity conservation. In Argentina, it is represented by the Paranense Forest, which covers a vast area of Misiones Province between the Paraná and Uruguay rivers. The Uruguay River is a global hotspot of freshwater gastropod diversity, here mainly represented by Tateidae (genus Potamolithus) and to a lesser extent Chilinidae. The family Chilinidae (Gastropoda, Hygrophila) includes 21 species currently recorded in Argentina, and three species in the Uruguay River. The species of Chilinidae occur in quite different types of habitats, but generally in clean oxygenated water recording variable temperature ranges. Highly oxygenated freshwater environments (waterfalls and rapids) are the most vulnerable continental environments. We provide here novel information on three new species of Chilinidae from environments containing waterfalls and rapids in the Uruguay River malacological province of Argentina. Materials and Methods: The specimens were collected in 2010. We analyzed shell, radula, and nervous and reproductive systems, and determined the molecular genetics. The genetic distance was calculated for two mitochondrial markers (cytochrome c oxidase subunit I–COI- and cytochrome b -Cyt b-) for these three new species and the species recorded from the Misionerean, Uruguay River and Lower Paraná-Río de la Plata malacological provinces. In addition, the COI data were analyzed phylogenetically by the neighbor-joining and Bayesian inference techniques. Results: The species described here are different in terms of shell, radula and nervous and reproductive systems, mostly based on the sculpture of the penis sheath. Phylogenetic analyses grouped the three new species with those present in the Lower Paraná-Río de la Plata and Uruguay River malacological provinces. Discussion: Phylogenetic analyses confirm the separation between the Uruguay River and the Misionerean malacological provinces in northeast Argentina. These new endemic species from the Uruguay River add further support to the suggestion that this river is a diversity hotspot of freshwater gastropods (with 54 species present in this basin, 15 of them endemic). These endemic species from environments with rapids and waterfalls should be taken into account by government agencies before the construction of dams that modify those ecologic niches in the Uruguay River.

Two new species of Chilina Gray from Cuyo Malacological Province, Argentina (Gastropoda: Hygrophila: Chilinidae)

The family Chilinidae in Argentina has been thought to include 19 species. We provide new information on the shells, radulae, reproductive and nervous systems, and the molecular genetics of the chilinid species from the Cuyo Malacological Province (as defined by Núñez, V., Gutiérrez Gregoric, D.E. & Rumi, A. (2010) Freshwater gastropod provinces from Argentina. Malacologia 53, 47–60), along with the description of two new species. Chilina sanjuanina n. sp. is characterized by a small shell with a conical and low spire and with one columellar tooth, a radula with an asymmetric central bicuspid tooth, and a penis sheath with an inner sculpture with regular conical pustules over the entire surface. Chilina cuyana n. sp. has a small shell with a low spire and two columellar teeth and a radula with an asymmetric tricuspid central tooth with serrated edges. The other two species in this province, Chilina mendozana and Chilina parchappii, are redescribed. Mitochondrial gene cytochrome c oxidase subunit I sequences between C. sanjuanina and C. mendozana differ by 4%.

Systematic Revision of Chilina Gray (Gastropoda: Pulmonata) from Northwestern Argentina and Description of a New Species

ABSTRACT The family Chilinidae in Argentina has been thought to include 17 species, most being found in Patagonia. All the original descriptions were based mainly on shell characteristics. The present work contains information about the shells, the radulae, and the reproductive and nervous systems in Chilinidae species from northwestern region, along with the description of a new species. This new species from Tucumán Province is characterized by the shell and a penial morphology that includes pustules and transverse lamellae with irregular contours and longitudinal folds. The taxonomic position of Chilina tucumanensis is also reviewed and a redescription of Chilina portillensis is provided. Additional information is provided on their habitats and distributions. These records in northwestern Argentina now increase the total number of species of Chilina inhabiting Argentina to 19.

Chilina iguazuensis (Gastropoda: Chilinidae), New Species From Iguazú National Park, Argentina

The Chilinidae comprises 16 species currently cited for Argentina, mostly distributed in Patagonia. All original descriptions of these species have been based on shell characters, and their internal anatomy is poorly known. Here a new species, Chilina iguazuensis, is described, including shell, radula, and reproductive and nervous systems. This species, found in Iguazú National Park, Misiones Province, Argentina, in the Upper Iguazú River rapids, has the following distinctive characteristics: aperture length equal to last whorl length; central radular tooth asymmetric and bicuspid, with both cusps serrated; and prepuce length 60% of penis sheath length. Chilina iguazuensis is endemic in Iguazú National Park, along with Chilina megastoma, which inhabits waterfalls in the same river.