Ontogenetic variation of the ossicles in Pseudothyone belli (Ludwig, 1887) with a description of a new Sclerodactylidae (Echinodermata: Holothuroidea: Dendrochirotida) from Southwestern Atlantic

ABSTRACT

In this paper, data about ontogenetic variation of dermal ossicles in Pseudothyone belli, a species widely distributed in the western Atlantic are provided. These data are important since juveniles often lack many of the characters used to identify adult specimens and in some cases, they have been described as separate species. The main differences between juveniles and adults are related to the form of knobbed buttons in the body wall (adults). The juveniles have four-holed and multilocular buttons, whereas the adults have only (or predominantly) four-holed buttons. Additional differences are related to the plates, which are knobbed in juveniles and smooth in adults. Although these ossicles are subject to wide variation, the ossicles from the introvert and tentacles are quite consistent in both juveniles and adults. In addition, a new species of Sclerodactylinae, collected along of the Brazilian coast is here described. Havelockia smirnovi sp. nov. is characterized by having two pillared body wall tables; discs four-holed, with oval and undulating margins; spire often undeveloped or ending in few teeth (2–4). Introvert with rosettes and two-pillared tables; table pillars united at the top and forming a cluster of teeth. Tentacles with rosettes and tube feet with two-pillared supporting tables, arched plates and end plates.

KEYWORDS:

• Sclerodactylinae
• Havelockia
• Brazil
• ontogeny
• new species

Acknowledgements

I am thankful to Marcos Tavares (MZUSP), Jon Norenburg (USNM) and Marc Eleaume (MNHN) for granting access to the museum collections under their responsibility and Carla Menegola (Laboratório de Porifera, UFBA) for logistical support. Instituto Gonçalo Moniz (FIOCRUZ/BA) for SEM analysis. Also, Wagner Magalhães (University of Hawaii at Manoa) for his helpful comments on the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author.

ORCID

Luciana Martins http://orcid.org/0000-0002-8107-3265