Discometra luberonensis sp. nov. (Crinoidea, Himerometridae), a new feather star from the Late Burdigalian
Author
Eléaume, Marc
66D3D76C-62AC-4B6D-9A3B-2A2665EA4DB9
Muséum national d’histoire naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, CP 51, 57 rue Cuvier, 75231 Paris Cedex 05, France.
marc.eleaume@mnhn.fr
Author
Roux, Michel
7E6DF41A-A61D-48B2-99EE-A43021E3E739
Muséum national d’histoire naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, CP 51, 57 rue Cuvier, 75231 Paris Cedex 05, France.
mich.roux51@gmail.com
Author
Philippe, Michel
457B0CA9-3D41-45FC-A20B-3090B2FA8F18
Centre “ Louis Lortet ” de conservation et d’étude des collections (Musée des Confluences, Lyon) 13 A, rue Bancel - 69007 Lyon, France.
mipauphi@wanadoo.fr
text
European Journal of Taxonomy
2020
2020-12-29
729
121
137
journal article
9070
10.5852/ejt.2020.729.1193
549807f7-2ce5-43fa-8a14-84f13c4ca82c
4419816
6F302AF9-0F04-4380-BA86-5A585C751711
Family
Himerometridae
A.H. Clark, 1908
Remarks
Hess & Messing (2011)
placed
Himerometridae
within the superfamily
Mariametroidea A.H.
Clark, 1909
(later changed to
Himerometroidea
by
Taylor
et al.
2017
) in which rod-shaped basals are absent.All genera in
Himerometridae
(
Heterometra
A.H.
Clark, 1909
,
Himerometra
,
Craspedometra
A.H.
Clark, 1909
,
Amphimetra
A.H.
Clark, 1909
), except
Discometra
, show coelomic grooves on the adoral side of centrodorsal.
Amphimetra
has multiple radiate coelomic grooves while
Heterometra
,
Himerometra
and
Craspedometra
show Y-shaped grooves with more or less wide branches. In
Discometra
, such Y-shaped features are present as canals included in the stereom and located just beneath the surface of the proximal facet of radials (
Fontannes 1880
; Sieverts-Doreck 1961). As a consequence, coelomic grooves are absent from the adoral surface of the centrodorsal. In
Himerometra
, the aboral facet of each radial displays a pair of wide grooves running in parallel in the inner part and diverging in a Y shape in the outer part; this feature is also visible on the oral side of the centrodorsal (
Fig. 3A
). Coelomic groove patterns are very similar in
Himerometra
(
Fig. 3A
) and
Discometra
(
Fig. 4
) but differ markedly in each of the other genera (
Rasmussen 1978
: figs 593–594). The numerous radiating coelomic grooves (A.H.
Clark 1915
) distinguish
Amphimetra
the most from the other genera, and Hemery (2011),
Summers & Rouse (2014)
and
Taylor
et al.
(2017)
questioned its attribution to
Himerometridae
. In
Himerometra
, the general shape of the centrodorsal varies from hemispherical to almost discoidal. The insertions of cirri on the centrodorsal have a very variable aspect on the same individual, with or without a slight rectangular transverse relief (
Fig. 3B
). The radial circlet delimits a more or less wide adoral cavity whose flanks corresponding to the inner face of the radials are sculpted by strong vermiculate figures (
Fig. 3C
). The distal articular facet of the radials is sub-trapezoidal, the internal (adoral) ligamentary areas, with no distinguishable limit adorally, are separated by a large depression, and the muscular areas are reduced and nearly inconspicuous (
Fig. 3D
).
Stratigraphical range
Miocene–Recent (Western Pacific), possibly since the Eocene.