First description of egg masses, oviposition and copulation of a neglected apple snail endemic to the Iguazú and Alto Paraná Rivers

ABSTRACT

The Ampullariidae have attracted persistent scientific interest, although this has been mostly concentrated on a few invasive species. Pomacea americanista (Von Ihering, 1919) new combination is a neglected species as there has been no published information about its anatomy and natural history since its description in 1919. Our aim was to describe its egg masses, oviposition and copulation to compare them with those of other Ampullariidae. We made observations on egg masses in the Iguazú River and tributaries and on snails reared in the laboratory. Pomacea americanista exhibited the same reproductive mode as other Pomacea species: aerial egg masses composed of hundreds (mean 186.12) of eggs with calcareous shells (mean 3.1 mm in diameter) that are deposited on emergent substrates, mostly rocks. The egg masses were a characteristic pale pink that distinguishes them from those of other species of Pomacea. Embryonic development took nearly 17 days at 26 °C. Hatchlings had a smooth shell with 1⅛ whorls (mean 2.6 mm in diameter) and began to breathe air and feed within a few hours. Copulation was subaquatic and long lasting (mean 16.13 h) and both sexes were highly promiscuous. The evidence gathered supports the hypothesis that P. americanista belongs to the genus Pomacea.

http://zoobank.org/urn:lsid:zoobank.org:pub:6484308C-3128-4013-ACCA-A274176958DE

KEYWORDS:

• Ampullaria
• Asolene
• Caenogastropoda
• eggshell
• embryonic development
• Pomacea americanista
• Pomacea megastoma
• Pomella
• perivitelline fluid
• Río de la Plata Basin

Acknowledgements

The egg masses were collected with the required legal permissions from APN (Administración de Parques Nacionales, Project NEA 380). We are grateful to the staff of Parque Nacional Iguazú and CIES (Centro de Investigaciones Ecológicas Subtropicales) who allowed and helped us to conduct our field research. FMG is a doctoral fellow and SB and PRM are researchers in CONICET. We wish to thank two anonymous reviewers and the editors for their helpful comments and suggestions on the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Pablo R. Martín http://orcid.org/0000-0002-2987-7901

Additional information

Funding

The present study was funded by grants from CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas, PIP 112-200901-00473), UNS (Universidad Nacional del Sur, PGI 24/B185) and ANPCYT (Agencia Nacional de Promoción Científica y Tecnológica, Fondo para la Investigación Científica y Tecnológica, PICT 2012-1956).