Williriedellum labeosum Dumitrică, 2022

Dumitrica, Paulian, Dieni, Iginio & Massari, Francesco, 2022, Valanginian Radiolarians Of Ne Sardinia (Italy) In The Frame Of The Weissert Event, Acta Palaeontologica Romaniae 18 (2), pp. 97-159 : 121-123

Williriedellum labeosum Dumitrică n. sp.

Figs. 10 d-f, j-j2

Description. Shell three-chambered, globular with tuberculate abdomen. Tubercles interconnected by simple or double costae forming a network of triangular surfaces. Pores of abdomen dense, circular and quincuncially arranged. Apex of most tubercles with a larger pore. Cephalothoracic body enclosed with lower half of thorax in abdominal cavity. Surface of cephalothorax with a network of thin ribs forming very small irregular polygonal surfaces with one small pore in each polygonal depression. Sutural pore with protruding rim and closed inside by a sieve structure ( Fig. 10e ). Aperture funnel-shaped bordered by a large protruding rim and closed, at the level of the inner side of wall, by a very thin network of very small pores ( Fig. 10f, j 2 ).

Studied material. Three illustrated specimens in samples OZ834 and 837.

Holotype. Specimen illustrated on Fig.10 j-jb, coll. MGP-PD, stub PD120 -OZ837- R06-07 .

Dimensions. Length 152-164 µm, diameter of abdomen 152-166 µm.

Etymology. From the Latin labeosus, -a, -um = thicklipped, due to the distal aperture with thick and protruding border.

Remarks. This species is very close to the Lower Cretaceous species W. gilkeyi Dumitrică, 1972 , by having the surface costate and cephalothoracic body partly enclosed in the abdominal cavity; however, it differs from it by having a funnel-shaped aperture with opening closed by a sieve structure. From the Upper Jurassic species W. crystallinum Dumitrică it also differs by its distal aperture, which is not simple.

Occurrence. Upper Valanginian , Sardinia .

Figures

Fig. 10 a-c1 - Hemicryptocapsa (?) bellireticulum (Wu & Li): a - OZ825, b - OZ836. c - OZ838, c1 - OZ824. d-f, j-j2 - Williriedellum labeosum Dumitrică n. sp.: d, e, j-j2, OZ837, f - OZ834. g, g1 - Cryptamphorella circumthoracica Dumitrică n. sp., OZ838; g1 - view of apical part. h, k-o – Cryptamphorella dumitricai Schaaf: h - detail of sutural pore, k - OZ825, l - OZ 824, m - OZ838, n-o, OZ839. i, i1- Williriedellum gilkei Dumitrică, OZ838. p - Zhamoidellum ovum Dumitrică, OZ839. r - Williriedellum cordiforme Dumitrică n. sp., OZ837. s, s1 - Williriedellum occultithorax Dumitrică n. sp. in lateral and obliquely apical views, OZ826. t-t2 – Cryptamphorella crassilabrosa Dumitrică n. sp., OZ837: t, t1 - holotype in two positions, t2 – sutural pore much magnified showing inside the wall of the hidden thorax. Figs. a-f, i, h, k-o, r x250; g, gi, h, t, t1 x300.

Fig. 2 Geological section across the S’Ozzastru area (trace A-A’ in the geological map of Fig. 1). Legend: a - Recent and present alluvial deposits (Holocene). b - Cuccuru ’e Flores Conglomerate: sandstone and breccia (middle Eocene). c - Siniscola Marl: marl (1) and marly limestone (2) (late Valanginian). d - Schiriddè Limestone: cherty limestone (early Valanginian). e - Monte Bardia Limestone: limestone (early Tithonian - late Berriasian). f - S’Adde Limestone: limestone and cherty limestone (latest Bathonian - earliest Tithonian). g - Dorgali Formation: dolostone (middle-late Bathonian). h - Metamorphic basement (Palaeozoic). i - Fault (modified from Bottini et al., 2018).