Scanning electron microscopy studies of the caudal appendix of Stenalpheops anacanthus (Decapoda: Pleocyemata: Alpheidae)

Stenalpheops anacanthus Miya, 1997 is a commensal alpheid shrimp that inhabits burrows shared with other crustaceans and possesses a distinctive caudal appendix. In this study, scanning electron microscopy was used to examine the morphology of this structure and its associated surface structures. The caudal appendix is narrow and lamellar, gradually tapering from base to tip and exhibiting incomplete longitudinal curling. Apparent segmentation results from periodic constrictions along the lateral margins. The surface features numerous circular pores and two types of projections—simple and conical—showing certain external morphological similarities to sensilla on the second antenna. These observations provide a morphological basis for future investigations of the functional significance of this unique appendage and contribute to understanding the evolution of similar appendage structures across different crustacean lineages.