Revision of the genus Thetidos Hedley, 1899 (Gastropoda: Conoidea: Raphitomidae) in the Indo-Pacific with descriptions of three new species

Abstract

The genus Thetidos was established to accommodate a single species Thetidos morsura, a minute turriform conoidean with an unremarkable paucispiral protoconch, but possessing characteristic globose whorls of the teleoconch and three strong denticles on the inside of outer apertural lip. Subsequently, Thetidos was considered synonymous with Lienardia, and has rarely been mentioned in literature until the recent discovery of a remarkably similar species Thetidos tridentata, though it is different in protoconch morphology. Both molecular data and protoconch morphology unequivocally suggested placement of the new species in Raphitomidae. Examination of shells from the Indo-Pacific identified a number of similar forms, all referable to the genus Thetidos. Six species are now recognized within the genus; of them three, Thetidos puillandrei n. sp., Thetidos minutissima n. sp., Thetidos pallida n. sp., are here described as new. Thetidos species are now known from subtidal depths from the Philippines and Sulawesi to French Polynesia. Thetidos morsura is the only species of the genus that possesses a paucispiral protoconch suggestive of a non-planktotrophic development, although it displays a wide geographic range and a high morphological variability.

http://zoobank.org/urn:lsid:zoobank.org:pub:1F2001CC-6BEA-4B26-AFB8-6B337E101FDB

Keywords:

• taxonomy
• turrid
• protoconch morphology
• planktotrophic development
• biogeography
• molluscan diversity

Acknowledgements

We are grateful to the MNHN team, Philippe Bouchet, Virginie Héros, Philippe Maestrati, Barbara Buge and Nicolas Puillandre for the access to the MNHN material, the basis of the present study. This material originates from several expeditions to the Philippines, Vanuatu and Papua New Guinea, which were funded by a consortium of agencies, including the Total Foundation, the French Ministry of Foreign Affairs, the Richard Lounsbery Foundation, the Philippines Bureau of Fisheries and Aquatic Research (BFAR) and the Niarchos Foundation, Prince Albert II of Monaco Foundation, and conducted by MNHN and Pro-Natura International (PNI) as a part of their Our Planet Reviewed programme. We are grateful to Dr Mandy Reid and Janet H. Waterhouse (AMS, Sydney) for lending the holotype of Thetidos morsura. We are also thankful to our referees John Tucker and Dr Winston Ponder, whose suggestions helped to improve the manuscript.

The present study was accomplished during a visiting curatorship of the first author in MNHN and was partly supported by a grant from the [Russian foundation of basic researches: RFBR-14-04-31048] (PI A. Fedosov).