AN ENIGMATIC TISSUE FOUND ON THE TONGUE OF CARDINALFISHES OF GENUS SIPHAMIA (PERCIFORMES, APOGONIDAE)

摘要

The cardinalfish genus Siphamia includes 23 species of small, bioluminous species that usually live in association with spiny or branched marine invertebrates such as sea urchins. An unusual whitish tissue on the tongue (Figs. 1, 2) and, sometimes, in the gill chamber of males was discovered during the examination of the specimens for a taxonomic revision of this genus. To our knowledge this tissue has not been observed in other species of fishes. Soon after its discovery the tissue was illustrated and the external morphology described briefly in two papers the first of which also speculated on its possible function. The aim of this study is to describe in detail the structure and nature of the tissue and to elucidate it function. In this presentation we provide a structural and histological characterization of this unknown tissue. Observations of tissue preparations were made using a light microscope, as well as scanning and transmission electron microscopy (SEM/TEM). Sections for light microscopy were stained with Toluidine Blue, combined Alcian Blue-PAS (acid and neutral mucins), combined Aldehyde Fuchsin-Alcian Blue (sulphated and carboxylated mucins), and Bromophenol Blue (proteins).