INTRODUCTION
Bioluminescent organs in fishes that produce ventral camouflage against a background of downwelling light are very common, yet their anatomy often is poorly understood (Hastings, 1971; Young & Roper, 1976). Camouflage via ventral bioluminescence has evolved at least seven times within a wide range of teleosts (Haddock et al., 2010; Davis et al., 2014, 2016) and they vary greatly in the anatomical structures that form them (Haygood et al., 1994; Chakrabarty et al., 2011; Ghedotti et al., 2015, 2018).
The luminous roughies (genus Aulotrachichthys) have a light organ in the region of the anus that houses lumiescent bacteria in the genus Photobacterium. Kuwabara (1955) and Haneda (1957) discuss the anatomy and function of the bioluminescent organ in A. prosthemius noting that it contained Photobacterium in lobules in an area around the anus (Fig. 1) and a light conducting structure they called the “unknown” structure or the filiform body respectively.
We seek to determine more specifically the structure of the bioluminescent organ in A. prosthemius and determine if Paratrachichthys, a closely related genus, is similarly bioluminescent. We also generate a phylogeny to better understand the evolution of bioluminescence in the Family Trachichthyidae
