Petraster crozonensis, Blake, Guensburg & Lefebvre, 2016

Blake, Daniel B. & Lefebvre, Bertrand, 2024, Ordovician Petraster Billings, 1858 (Asteroidea: Echinodermata) and early asteroid skeletal differentiation, Comptes Rendus Palevol 23 (17), pp. 217-239 : 224

publication ID	https://doi.org/ 10.5852/cr-palevol2024v23a17
publication LSID	urn:lsid:zoobank.org:pub:C0E27E25-6719-40FD-A2B8-829B484D6C13
DOI	https://doi.org/10.5281/zenodo.14232125
persistent identifier	https://treatment.plazi.org/id/267CF001-7935-FFFC-A734-FE059E2AF84A
treatment provided by	Felipe
scientific name	Petraster crozonensis
status

Treatment

Petraster crozonensis Blake, Guensburg & Lefebvre, 2016

( Fig. 4)

Petraster crozonensis Blake, Guensburg & Lefebvre, 2016: 169 , figs 6.1-6.9, 7.1, 7.2. — Blake 2018: pl. 2, fig. 16; pl. 5, figs 3, 4.

DIAGNOSIS. — Aboral ossicles proportionately robust, uniform, closely fitted, smaller accessories not recognized. Carinals, adradialia recognized. Axillary enlarged, triangular, reaching disk margin. Actinal ossicles few if developed. Axial transverse ridge “J”-shaped.

MATERIAL EXAMINED. — Two incomplete specimens, LPB 15174, LPB 15175, E.N.K. Clarkson collection, Université de Bretagne occidentale, Brest, France.

TYPE LOCALITY AND HORIZON. — Morgat harbor, Crozon, Finistère, France; Postolonnec Formation, Morgat Member, Linochitina pissotensis chitinozoan Zone, late Darriwilian, Middle Ordovician.

DESCRIPTION

Petraster in which arms are moderately elongate, R reaching at least c. 22 mm. Aboral series (i.e., all series aboral of inferomarginals) of arms appearing proportionately moderately robust and quite closely abutted; smaller accessories intercalated among larger not recognized. Carinals with bordering adradialia, superomarginals clearly developed, ossicles similar, ovate, thickened; inferomarginals as exposed in aboral aspect appearing enlarged relative to superomarginals; inferomarginals slightly offset from superomarginals. Disk superomarginals thought to be only weakly differentiated, recognition based on differentiation of three ossicle series, including intermarginals ( Fig. 4B 1). In oral aspect, inferomarginals robust, closely abutted, approximately equidimensional, ossicular sizes appearing to diminish in size abruptly on arms; form elliptical, bulbous. Axillary triangular, narrowing distally, barely reaching lateral edge of inferomarginals series. Actinal ossicles few and small if present.

Axials relatively wide, adradial ridge elongate, termini overlapping; transverse ridge broadly “J”-shaped, transverse water-vascular channel well-defined. Adaxials possibly elliptical and transversely elongate; weak nose possibly developed.

REMARK

Petraster crozonensis is separated from P. caidramiensis n. sp. and P. kinahani by presence of clearly differentiated, aligned, and similar distal carinal, adradial, and superomarginal ossicles; arm intercalated granules absent; axial single, enlarged, triangular, reaching the disk margin; axials rectangular, overlapping, transverse ridge “J”-shaped.