Two new species of Oregodasys (Gastrotricha: Macrodasyida: Thaumastodermatidae) from Carrie Bow Cay, Belize with ultrastructural observations of the epidermal glandular system

Abstract

This study represents the first report of Gastrotricha from the coast of Belize. Two new species of Oregodasys (Macrodasyida: Thaumastodermatidae) are described from sublittoral sediments around the island of Carrie Bow Cay in the Belizean barrier reef complex. Oregodasys norenburgi sp. nov. is unique in the possession of paired red ocelli and in the quantity and distribution of lateral and posterior adhesive tubes. Oregodasys katharinae sp. nov. is allied with species that possess ventrolateral cirri in the posterior body region, but is distinguished based on the quantity of cirri and adhesive tubes and the bipartite structure of the caudal organ. Ultrastructural analysis of the bodywall of O. katharinae sp. nov. reveals a highly glandular epithelium covered by a bilayered cuticle consisting of a thin exocuticle and thicker endocuticle containing electron-dense elements. At least three types of papillae are present beneath the cuticle: blunt papillae, triangle-shaped papillae, and sensory papillae. The sensory papillae are two-part structures consisting of a porous epidermal cell and a monociliated epidermal cell. The ultrastructure of blunt papillae was not examined, but triangular papillae are formed from neck-like extensions of underlying glandulocytes and contain a pore to the external environment. Insunk glandulocytes are present between the various papillae and have an elongate neck that extends between epidermal cells. All glandulocytes contain a variety of membrane-bound secretory vesicles with a wide range of staining characteristics, from electron lucent to electron dense.