Histopathological Lesions Caused by a Digenean Trematode in a Pest Apple Snail, Pomacea canaliculata, in Its Native Geographic Distribution Area.

Pomacea canaliculata is one of the most dangerous invasive species. Morphological and molecular analyses have revealed that a digenean species belonging to the family Echinostomatidae parasitizes this snail at two sites in Buenos Aires Province, Argentina, South America. Molecular results confirmed that the species belongs to a genus closely related to Patagifer. Analysis of the 28S rDNA showed that the sequences of the rediae and metacercariae are identical, indicating that the apple snail acts as the first and second intermediate host. The cercariae may encyst as metacercaria inside the redia and also emerge and re-infect the same snail or another snail. The prevalence of digeneans was higher in one of the sampling locations (15.1% vs. 0.72%), probably because the bird species that acts as the definitive host is more abundant in that area. Histopathological examination showed that the parasite quickly invades multiple host organs (gills, intestines, albumen gland, lung, kidney, and mantle border) besides the gonad and digestive gland, as is usual in digeneans. In addition, the partial or total castration of snails was observed in cases of moderate and high infection intensity. In males, there was loss of integrity in testicular tubules, while in females, the replacement of ovarian tissue by rediae was found.

A new species of Liolaemus (Reptilia: Squamata) of the Liolaemus capillitas clade (Squamata, Liolaemini, Liolaemus elongatus-kriegi group) from Sierra de Velasco, La Rioja Province, Argentina.

A new species of the Liolaemus capillitas clade is described. Liolaemus galactostictos sp. nov. differs from other members of its group by a combination of morphological and molecular traits, in particular its black dorsal coloration pattern not found in any other Liolaemus species. Liolaemus galactostictos sp. nov. is only known from its type locality. This new species is found in rocky fields surrounded by grasslands on the top of the Velasco Mountains, a ¨sky island environment¨, in northwestern Argentina. As well as other members of its clade this species seems to be strictly saxicolous, viviparous and feeds on insects.

Alternative methods of phylogenetic inference for the Patagonian lizard group Liolaemus elongatus-kriegi (Iguania: Liolaemini) based on mitochondrial and nuclear markers.

We present different approaches to a multi-locus phylogeny for the Liolaemus elongatus-kriegi group, including almost all species and recognized lineages. We sequenced two mitochondrial and five nuclear gene regions for 123 individuals from 35 taxa, and compared relationships resolved from concatenated and species tree methods. The L. elongatus-kriegi group was inferred as monophyletic in three of the five analyses (concatenated mitochondrial, concatenated mitochondrial + nuclear gene trees, and SVD quartet species tree). The mitochondrial gene tree resolved four haploclades, three corresponding to the previously recognized complexes: L. elongatus, L. kriegi and L. petrophilus complexes, and the L. punmahuida group. The BEAST species tree approach included the L. punmahuida group within the L. kriegi complex, but the SVD quartet method placed it as sister to the L. elongatus-kriegi group. BEAST inferred species of the L. elongatus and L. petrophilus complexes as one clade, while SVDquartet inferred these two complexes as monophyletic (although with no statistical support for the L. petrophilus complex). The species tree approach also included the L. punmahuida group as part of the L. elongatus-kriegi group. Our study provides detailed multilocus phylogenetic hypotheses for the L. elongatus-kriegi group, and we discuss possible reasons for differences in the concatenation and species tree methods.

New species of Liolaemus (Reptilia, Squamata, Liolaemini) of the Liolaemus donosobarrosi clade from northwestern Patagonia, Neuquén province, Argentina.

Two new species of the Liolaemus donosobarrosi clade are described. Liolaemus tirantii sp. nov. and Liolaemus calliston sp. nov. differ from other members of their clade by a combination of coloration characters, morphometric and molecular traits. Liolaemus tirantii sp. nov. is known from three localities separated only a few kilometers from each other and Liolaemus calliston sp. nov. is known only from the type locality. Both species inhabit a region strongly impacted by oil and gas extraction but their conservation status is unknown.

Molecular phylogenetic relationships of the lizard clade Liolaemus elongatus (Iguania: Liolaemini) with the description of a new species from an isolated volcanic peak in northern Patagonia.

A new species of the Andean-Patagonian Liolaemus elongatus clade is described. Liolaemus crandalli sp. nov. differs from other members of its clade by a combination of coloration characters, scale counts and genetic traits. Liolaemus crandalli sp. nov. is known only from an isolated volcanic mountain in northwestern Patagonia above 1500 m.a.s.l. unconnected with other habitat suitable for species of the Liolaemus elongatus clade.