Can the comparative study of the morphology and histology of the scales of Latimeria menadoensis and L. chalumnae (Sarcopterygii: Actinistia, Coelacanthidae) bring new insight on the taxonomy and the biogeography of recent coelacanthids?

Abstract

AbstractSEM (Scanning electron microscopy) and photonic microscopy (ground sections) studies confirm that the scales of the coelacanth Latimeria menadoensis have strong morphological and histological similarities with the scales of L. chalumnae. They are both elasmoid scales, the external layer of which is made of radial ridges that are overlaid, on the posterior field, by odontodes. The odontodes of L. menadoensis are made of the typical mineralized tissues described for teeth of the coelacanth and their width is similar to that of L. chalumnae odontodes. Globular corpuscles are found in the isopedine contact with the external layer. Their mineralization seems to be inotropic as in the Mandl's corpuscles of teleost elasmoid scales. Scale organisation in L. menadoensis does not show any characteristics that may support significantly, in the absence of additional evidence, two different species in the extant coelacanths.