Abstract The sewage snail Physa acuta, native to North America, is an effective invasive species around the world. In Chile, it was first reported in 2014 in the north central area of the country. So far, the species has not been recorded in southern Chile. Sampling performed in 2015 in three localities from Llanquihue Lake, Chilean Patagonia, only provided native freshwater snails. However, new collections performed in February 2018 in the same three sites were successful for physid specimens suggesting a biological invasion entailing a large southward range expansion of these snails. Here we performed morphological, microstructural and phylogenetic analyses to investigate whether the new samples belong to Physa acuta. The shell morphology, male copulatory complex and radula microstructure of the new material agree with those of the sewage snail. The molecular phylogenetic analyses using the cytochrome c oxidase subunit 1 (COI) gene confirmed morphological identification. We suggest to take prompt measures to prevent the expansion of Physa acuta in Llanquihue Lake or nearby aquatic ecosystems.

Abstract Some naidid oligochaetes establish commensal relationships with species of molluscs worldwide. In the present study, we report the finding of Chaetogaster limnaei in Illapel River, northern Chile. This worm was found inhabiting the mantle cavity of the freshwater gastropod Physa acuta, an invasive species in this country. The taxonomic status of C. limnaei was confirmed by molecular analysis based on mitochondrial 16S ribosomal RNA gene.

Resumen Los oligoquetos Naididae pueden establecer relaciones comensales con especies de moluscos alrededor del mundo. En el presente estudio se informa el hallazgo del oligoqueto Chaetogaster limnaei en el río Illapel, norte de Chile. Los animales se encontraron habitando la cavidad del manto del gasterópodo de agua dulce Physa acuta, una especie invasora en este país. El estado taxonómico de C. limnaei se confirmó mediante el análisis molecular basado en secuencias de ADN del gen mitocondrial del ARN ribosomal 16S.

In this work the epipodium morphology of the marine snail Prisogaster niger is described. In this gastropods the epipodium includes a complex of structures among which the neck lobes, epipodial ridge, epipodial tentacles and epipodial papillae constitute the most remarkable characters. Although these features are commonly found among trochoidean taxa, the observation of the epipodium, compared with the literature, revealed potential autapomorphic characters of diagnostic value for the genus and the subfamily Prisogasterinae, like epipodial lamellae and epipodial tuft.

En este trabajo se describe la morfología del epipodio del caracol marino Prisogaster niger. En esta especie el epipodio está conformado por un complejo de estructuras entre las cuales los lóbulos del cuello, rebordes epipodiales, tentáculos epipodiales y papilas epipodiales constituyen conspicuos caracteres. El estudio de la morfología del epipodio reveló potenciales autapomorfías de valor diagnóstico para la subfamilia Prisogasterinae.

This study describes the microscopic anatomy of the reproductive systems of the keyhole limpets Fissurella latimarginata and Fissurella cumingi to test the existence of a possible isolating reproductive mechanism of morphophysiological type between species, and consequently to determine if the findings provide a valid taxonomic characteristic to distinguish these sympatric species. The results show that in both species the reproductive system is intimately associated with the excretory system. The gonad has a septa organization, and is connected with the distal portion of the right kidney by means of a renopericardial duct which functions as a genital duct. The gametes are evacuated to the mantle cavity through the right kidney opening. Besides transport of the gametes, the genital duct, which connects with the pericardium through the nephrostome, bears a gland attached to its inner wall both in males and females. No marked anatomical differences were noted between the reproductive systems of the two limpets which would allow their unequivocal taxonomic differentiation at the species level

Este trabajo describe la anatomía microscópica del sistema reproductivo en las lapas Fissurella latimarginata y Fissurella cumingi, para examinar la posible existencia de un mecanismo de aislamiento reproductivo del tipo morfofisiológico y consecuentemente, determinar si el sistema reproductivo presenta algún carácter taxonómico válido que permita distinguir estas especies simpátricas. Los resultados muestran que en ambas especies y sexos el sistema reproductivo se relaciona con el sistema excretor. La gónada, de organización en septos, comunica con la porción distal del riñon derecho distal por medio del canal renopericárdico que funciona como conducto genital. Los gametos son evacuados a la cavidad del manto a través de la apertura renal derecha. Además de transportar los gametos, el conducto genital, que comunica con el pericardio a través del nefrostoma, presenta una glándula adosada a la pared interna en los machos y en las hembras. No se detectaron diferencias anatómicas marcadas del sistema reproductivo que permitan diferenciar las especies inequívocamente por lo que este sistema tiene bajo valor taxonómico a nivel específico