Valettaster thuyi, Gale, 2021
publication ID |
https://doi.org/ 10.1080/14772019.2021.1960911 |
publication LSID |
lsid:zoobank.org:pub:F8991F09-B5FB-40EF-B4CC-474D925085B8 |
DOI |
https://doi.org/10.5281/zenodo.10883585 |
persistent identifier |
https://treatment.plazi.org/id/B9207C41-9A5A-FFD6-0CF7-FACFFDF4FD77 |
treatment provided by |
Felipe |
scientific name |
Valettaster thuyi |
status |
sp. nov. |
Valettaster thuyi sp. nov.
( Fig. 22M, N View Figure 22 )
Type. The specimen figured here ( Fig. 22M, N View Figure 22 ) is the holotype, from the Hildoceras bifrons ammonite Zone (Toarcian) at Fougerolles, France ( MHNML 2020.1.1) .
Diagnosis. Valettaster with tabulate abactinal ossicles, the broad outer surface of which bears a branching reticulum of imperforate stereom.
Derivation of name. After Ben Thuy , who sent the holotype specimen to the author .
Material. Holotype, a single abactinal ossicle, obtained by Marc Chesnier from washed residues from the Gúerin quarry at Fougerolles, Normandy, France (see Hess & Thuy 2016 for details).
Description. Abactinal ossicle with outline irregularly semicircular, 3 mm in maximum dimension; one side is straight, the other bearing irregular short lobes. The ossicle is flat, with a broad external surface slightly narrower than basal breadth. The external surface shows a radial network of irregularly bifurcating ridges of smooth imperforate stereom.
Remarks. This is by a considerable margin the oldest known representative of Valettaster (185–190 Ma), and the similarity of its highly specialized sculpture (reticulum of imperforate stereom) to that of the Cretaceous V. argus and V. ocellatus confirms its placement in the genus. It differs from V. ocellatus in the thinner abactinals, the very broad external surface and the irregularly bifurcating, radial ribbing. In V. ocellatus the abactinals are stout truncated cones, and the sculpture comprises fine radial ridges and pustules ( Fig. 22E View Figure 22 ).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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