Larval and early post-larval shell of three deep-sea Scaphopoda (Mollusca) from the southwest Atlantic

ABSTRACT

The larval shells of Antalis circumcincta (Watson, 1879) (order Dentaliida), Pertusiconcha callithrix (Dall, 1889) (order Gadilida) and of an undetermined species of uncertain systematic position are described. The material studied comprises mainly samples from deep waters, collected by expeditions along the southeast coast of Brazil. The larval shell of the three taxa matches other types previously described in the literature. Antalis circumcincta and P. callithrix have four regions (protoconch A, protoconch B, teleoconch A, teleoconch B), but differ in dimensions and sculpture from each other, while the undetermined species has three regions (protoconch A, protoconch B, teleoconch B). A morphometric approach combined with a discriminant analysis also indicates that the three taxa are significantly distinct. This study confirms patterns of larval shells at the taxonomic rank of orders but other supraspecific patterns remain uncertain.

KEYWORDS:

• Dentaliida
• Gadilida
• Entalimorpha
• Dentaliidae
• Entalinidae
• praetubulus
• protoconch
• benthos
• Campos basin
• morphometry

Acknowledgments

We are grateful to Dr. C. Oliveira (IBUFRJ), Dr. R. Absalão (IBUFRJ), and Dr. A. Pimenta (MNRJ) for loans and access to the material. We thank Dr. Gerhard Steiner (Universität Wien), Dr. Daniel Geiger (SBMNH), Dr. Don Colgan (AMS) and one anonymous reviewer for the contributions to the manuscript. Ivan Nekhaev (Saint Petersburg State University) donated comparative material of juvenile scaphopods. Beatriz Cordeiro and Camila Messias operated the SEM at Invertebrate Department (MNRJ). Petrobras S.A. made the collection and study of material possible. P.M.S. Vilela and L.S. Souza acknowledge UNIRIO and CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico/ CNPq/MCTI/FAP/PROTAX #001/2015), respectively, for scholarships.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Leonardo Santos de Souza http://orcid.org/0000-0002-8242-010X