Redescription of the first post-embryonic stage (zoea) of the shrimp Athanas nitescens (Leach, 1814) (Crustacea: Caridea)

• Grant number: 23/03695-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2023
• End date: December 31, 2023
• Field of knowledge: Biological Sciences - Zoology - Morphology of Recent Groups
• Principal Investigator: Rogério Caetano da Costa
• Grantee: Nádia de Moraes Sanches
• Host Institution: Faculdade de Ciências (FC). Universidade Estadual Paulista (UNESP). Campus de Bauru. Bauru , SP, Brazil
• Associated research grant: 18/13685-5 - Integrative analysis of the Brazilian fauna of decapod crustaceans: taxonomy, phylogenetic systematics, spermiotaxonomy, morphology of post-embryonic development, ecology and conservation, AP.BTA.TEM

Abstract

Athanas is a genus of small marine shrimp belonging to the family Alpheidae which is known to present species with cryptic life habits. It is naturally distributed in the eastern Atlantic and Mediterranean Sea, however it was first reported in Brazil off the coast of São Paulo in São Vicente and later in Cananeia living on rocks. Even though it is very abundant in its natural environment its biology is poorly known probably due to its life habit and its small size, but there are some records about its life cycle as the description of its first two larval stages (zoeae) made by Sars, 1906 and redescribed by Bartilotti et al., 2005, because the previous description reported characteristics common to more advanced stages in larvae of Alpheideos. This highlights the importance of revisions in larval descriptions, as stages may be missed due to lack of knowledge of the timing of moulting and features may be missed due to the limitations of the technologies in place at the time of the descriptions. The objective of this paper is to redescribe the first post-embryonic stage (zoea I) of the shrimp Athanas nitescens by illustrating its appendages. And to make the comparison with the description already made. The target specimen of this study was collected on November 21, 2021, in São Sebastião, northern coast of the State of São Paulo, in the Araça estuarine region during low tide. Ovigerous females of Athanas nitescens were collected in the intertidal region by active search, conditioned in plastic bags with salty water, and taken to the laboratory where they were kept under controlled temperature and salinity conditions until the larvae hatched. After hatching the best larvae were fixed in glycerinated alcohol to be dissected. Appendages will be dissected using larval stylets in a ZeissStemi 2000C trinocular stereo microscope, and measurements and drawings under a Leica DM750 microscope equipped with a camera lucida. Total length (CT) and carapace length (CC) will be measured. All drawings and measurements will be based on 10 different specimens. With the execution of this work it will be possible to identify the species Athanas nitescens not only in its adult stage, but also in its first stage of post-embryonic development, which will allow an easier identification when the larvae were collected in the natural environment.