Microdermatoglyphic patterns in scutes are highly conserved among sea turtle species

6 pages, 2 figures, 1 tables

While shape and distribution of epidermal scales and scutes at the macro-level (> 1 mm) are commonly used to distinguish between species and even conspecifics, microdermatoglyphic (< 1 mm) patterning is still unknown for many reptile taxa. We used Scanning Electron Microscopy to provide the first characterisation of the microdermatoglyphic patterns on the scutes of all hard-shelled sea turtles (Caretta caretta, Chelonia mydas, Eretmochelys imbricata, Lepidochelys kempii, L. olivacea, Natator depressus) and the leatherback turtle (Dermochelys coriacea), as well as from the diamondback terrapin (Malaclemys terrapin), the painted turtle (Chrysemys picta), and the red-footed tortoise (Chelonoidis carbonarius). All sea turtles and the diamondback terrapin had similar microdermatoglyphic patterns at all tested magnifications (100x, 1000x, 5000x, and 10,000x), with interlocking or overlapping polygon-shaped cornified cells (= Oberhäutchen cells) of 10–50 μm in diameter that display on their surface a tight lattice of irregular microplicae that create pits of approximately 1 μm in diameter. These patterns appeared to be consistent across all life stages. Oberhäutchen cells were also present in the painted turtle, but with shallower microplicae, and the red-footed tortoise exhibited no visible microdermatoglyphic patterning. Our research indicates that microdermatoglyphic patterns are highly conserved within sea turtles even though variability does exist more broadly within the Testudines

Funding was made possible by American Association of University Professors research grants (241272, 241290, 241053) to T. Pinou. NJR was funded by the Spanish Agencia Estatal de Investigación through the Ramon y Cajal postdoctoral program (RYC2021-034381-I). Institutional support was provided to the Institut de Ciències del Mar by the Spanish Government as a “Severo Ochoa Centre Excellence” grant (CEX2019-000928-S)

Peer reviewed