Morphological study for understanding the sexual pattern in ghost shrimp Callichirus major (Crustacea: Axiidea)

Abstract

Callichirus major is a species of ghost shrimp that has burrowing habits, building underground galleries in the intertidal region of beaches. This study aimed to analyse some morphological parameters to verify its type of sexual pattern. A sample of 79 individuals, collected at the beach of Corujão, Espírito Santo, Brazil, was used. Data on the external morphology, presence of gonopores, carapace length (CL) and cheliped lengths (Lch) were obtained. In addition, the gonads were processed for histological analysis. The animals were divided into three categories: A, individuals with male characteristics; B, those presenting exclusively female characteristics; C, animals with characteristics of intersex, which presented supernumerary gonopores. Positive allometries were found for Lch versus CL only for category A, characterizing the group's marked heterochely. Histologically, it was possible to observe the presence of oocytes in category A and one case of male tissue in an intersex individual (category C). However, no genital ducts of both sexes were found in that individual. Callichirus major presents controversial sexual characters, which makes it difficult to understand the reproductive parameters and sexual pattern. However, maybe that species can develop a sexual system of hermaphroditism.

A new classification of Callianassidae and related families (Crustacea: Decapoda: Axiidea) derived from a molecular phylogeny with morphological support

“…Callichirus kraussi is here removed to its own genus, Kraussillichirus, on genetic evidence (Robles et al, in press) and uropodal endopods more typical of the family. Species of Callichirus may be functional hermaphrodites with some or all females having male gonopores (Souza et al, 2017(Souza et al, , 2018 Corallianassa Manning, 1987 Corallianassa Manning, 1987: 392-394.-Poore, 2004: 184.-Ngoc-Ho, 2005: 71.-Komai et al, 2015.…”

Integrative taxonomy reveals hidden species within the western AtlanticCallichirus majors. l. (Decapoda, Axiidea, Callichiridae)

“…However, evidence has been accumulating over many years that C. major is actually a species complex (Rodrigues and Shimizu 1997;Felder 1998, 1999a, b, c;Staton and Felder 1995;Felder and Robles 2009;Peiró 2012). Yet, the name continues to be widely and frequently used in ecological, distributional, morphological, checklists, and taxonomic researches carried out along its implied geographic distribution (Rodrigues 1966(Rodrigues , 1971(Rodrigues , 1983Souza and Borzone 1996;Blanco-Rambla 1997;Souza et al 1998;Coelho et al 2007;Botter-Carvalho et al 2007;Botter-Carvalho et al 2012;Rio et al 2019;Souza et al 2020). The current lack of clarity in the use of the name C. major has hence resulted in nomenclatural instability, but also in unreliability and miscommunication of the available ecological and distributional information.…”