Revaluation of the taxonomic characters and distribution of Omalonyx geayi (Gastropoda, Succineidae)

José W Thomé,Janine O Arruda,Gary M Barker

doi:10.1590/1678-4766e2016019

Abstract

ABSTRACT Omalonyx geayi Tillier, 1980 was originally described on the basis of specimens from Kaw swamp, French Guiana. This species distinguished from other of Omalonyx d'Orbigny, 1837: (i) by hermaphrodite duct twice as long and sacculate, without radial ducts but a funnel-shaped insertion on the ovariotestis, and (ii) by longitudinal wrinkled folds on the phallus inner wall. Two recent collections - from Trinidad and Carauari (Amazonas, Brazil) included specimens with ovariotestis and hermaphrodite duct morphologies similar to that originally described for O. geayi, but with phallus morphology not consistent with identification as O. geayi. A further eight lots, from Suriname, Ecuador, Brazil (Amazonas and Alagoas States), Bolivia and Cayenne-Kourou Road in French Guiana comprised specimens with phallus morphology analogous to O. geayi and ovariotestis and hermaphrodite duct similar to that of other Omalonyx species. Based on histological examination, and earlier phylogenetic analyses of morphological characters, we conclude that the ovariotestis and hermaphrodite duct conditions previously described for O. geayi were based on parasitized specimens. Accordingly, O. geayi is redescribed, and new information presented on the species' wide distribution in South America.

Highlights

Omalonyx geayi Tillier, 1980 was originally described on the basis of specimens from Kaw swamp, French Guiana
Earlier phylogenetic analyses of morphological characters, we conclude that the ovariotestis and hermaphrodite duct conditions previously described for O. geayi were based on parasitized specimens
Based on detection of parasites in the hermaphrodite ducts and ovariotestes in these histological preparations, and observations of anatomy by dissection of specimens across several Omalonyx species, we propose a recharacterization of Omalonyx geayi with emphasis on the reproductive system, and redefine the species’ geographical distribution

Summary

Introduction

Omalonyx geayi Tillier, 1980 was originally described on the basis of specimens from Kaw swamp, French Guiana. Two recent collections – from Trinidad and Carauari (Amazonas, Brazil) included specimens with ovariotestis and hermaphrodite duct morphologies similar to that originally described for O. geayi, but with phallus morphology not consistent with identification as O. geayi.

Results

Conclusion