Structure and sexual dimorphism of the first antennae in Penaeus vannamei, Boone, 1931

Abstract

ABSTRACT This contribution is a histological and scanning electron microscopy study of major flagellar setae of antennules from the most cultured crustacean species, Penaeus vannamei. Antennule samples were collected from females and males of selected species and processed for histological as well as scanning electron microscopy (SEM) evaluation. The histological and SEM description of major setae from antennules, namely aesthetascs, plumose setae, and male spines are presented in detail. A unique sexually dimorphic structure, male spines on the inner (medial) flagella, is reported for the first time in a penaeid shrimp. These spines are robust structures, short and thick with non-permeable cuticle and no terminal pore, innervated by receptor neuron clusters. This histological organization suggests the spines are sensilla for mechanoreception, possibly involved in courtship mechanoreception, complementing chemosensory information from aesthetascs. Additionally, SEM observations of other antennule setae are presented, including asymmetric setae associated with aesthetascs.