Taxonomic review of Metaxia (Gastropoda: Triphoridae) from Brazil, with description of a new species

Alexandre Dias Pimenta,Maurício Romulo Fernandes

doi:10.1590/s1984-46702011000600016

Abstract

The taxonomy of the species of Metaxia Monterosato, 1884 from Brazil is revised. Previously to this study, only Metaxia excelsa Faber & Moolenbeek, 1991 was known to occur in this country, under its older name Metaxia exilis (C.B. Adams, 1850). The review of a large amount of shells in malacological collections in Brazil revealed the occurrence of three known additional species: Metaxia taeniolata (Dall, 1889); Metaxia rugulosa (C.B. Adams, 1850); Metaxia prompta Rolan & Fernandez-Garces, 2008, all previously reported from the southeast coast of the USA and/or the Caribbean region. Metaxia gongyloskymnus sp. nov., diagnosed by the globose protoconch with continuous axial ribs and microscopic spiral sculpture, is restricted to localities off the Southeastern Brazilian coast.

Highlights

Triphoridae is a large group of marine microgastropods that includes both sinistral and dextral species
The dextral species are all included in Metaxiinae, that is characterized by the presence of crisp, zigzag spiral cords on the first embryonic whorls and subsequent whorls axially ribbed (MARSHALL 1977) and includes the 28 described species of Metaxia Monterosato, 1884 (APPELTANS et al 2011), which are distributed worldwide in tropical and temperate seas (MARSHALL 1983)
The only species recorded from the southwestern Atlantic is Metaxia excelsa Faber & Moolenbeek, 1991, which was recorded from Pará to Rio de Janeiro states, under its older name Metaxia exilis

Summary

MATERIAL AND METHODS

The taxonomic identifications were based on conchological comparisons with original descriptions and illustrations. Adams, 1850) non Cerithium exile Eichholtz, 1829, all literature on Brazilian mollusks continued to use the older, preoccupied name, M. exilis (e.g., RIOS 1994, 2009, ABSALÃO et al 2006, GOMES et al 2006, SANTOS et al 2007) This was the only species of Metaxia reported from Brazil, but previous records proved to be mixed with the other four taxa studied in this paper. USA: Carolina coast (type locality), Florida (CAMP et al 1998; ROSENBERG 2009), Texas (TUNNELL JR et al 2010); Cuba (ROLÁN & FERNÁNDEZ-GARCÉS 1992), Colombia (MERLANO & HEGEDUS 1994); Brazil: Bahia to Rio de Janeiro (this study).

20. Cerithiopsis rugulosum

DISCUSSION