Hiscocapsa aitai 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 : 125

Hiscocapsa aitai Dumitrică n. sp.

Figs. 11 i, i 1

1982 Sethocapsa sp. Foreman – Okamura & Uto, pl. 7, fig. 5.

Description. Shell four-segmented morphologically consisting of two distinct parts: a proximal conical part and a spherical distal part. Proximal conical part made up of a smooth poreless cephalis with an extremely small apical spine and some very small circular pores, a short trapezoidal outlined thorax and abdomen both perforated by pores separated by irregularly longitudinally disposed costae. Collar and lumbar intersegmental separations not evident externally but the lumbar one very well marked by the sudden inflation of the postabdominal chamber. The latter has large circular pores usually hexagonally framed externally and quincuncially disposed. Here and there some very small nodules can appear at some nodal points of the frame. Distal part a little pointed and containing a relatively large circular aperture with sharp bor- der.

Studied material. A single specimen in sample OZ824.

Holotype. The illustrated specimen, coll. MGP-PD, stub PD120 -OZ824- R13-07 .

Dimensions. Height of specimen 149 µm, of conical part 60 µm, diameter of base of conical part 53 µm, of postabdominal segment 108 µm, of distal aperture 23 µm.

Etymology. The species is dedicated to Dr. Yoshiaki Aita who was the first to examine some radiolarians from the Ozzastru section (see Dieni et al., 1987b, p. 148).

Remarks. The specimen from Sardinia resembles rather well the species illustrated by Okamura & Uto ( 1982) by external morphology and the presence of rare nodules on the surface of the postabdominal segment.

Range and occurrence. Very rare in the Sardinian samples and the probably Valanginian from Japan.

Figures

Fig. 11 a-b1 - Hiscocapsa grutterinki (Tan): a, OZ834, b, OZ839. c, c1, d, g - Hiscocapsa (?) ventriosa Dumitrică n. sp.: b, OZ839, c, OZ836, c1, aperture, g - complete specimen, V40, Svinița, Romania. e - Doliocapsa utoi Dumitrică n. sp., OZ824. f, f1, h, h1 - Hiscocapsa rugosacutis Dumitrică n. sp., OZ826. i-i1 - Hiscocapsa aitai Dumitrică n. sp., OZ824. p, s -Hiscocapsa lagunculoides Dumitrică n. sp., OZ834, OZ838; p1, s1- distal apertures of both specimens. j - Squinabollum cf. elegans Dumitrică n. sp., OZ826. k, k1 - Doliocapsa weisserti Dumitrică n. sp., OZ834. l - Hiscocapsa tuberculata Dumitrică n. sp., OZ826. m, m1, n - Doliocapsa erbae Dumitrică n. sp., OZ834. o – Doliocapsa favopora Dumitrică n. sp., OZ834. r - Doliocapsa mediterranea Dumitrică n. sp., OZ834. Figs. a-d, j x250; figs. c1, e, e1, f, f1, g, h, i, i1, k, k1, l, p, r x300, m-o, p1 x400.

Fig. 1 Geologic map of the Siniscola area, NE Sardinia (from Dieni & Massari, 1971, updated in 1986). Legend: a - Recent and present alluvial deposits (Holocene). b - Scree deposits (Würm-Holocene). c - Detrital cones mostly composed of gelifraction limestone clasts (“éboulis ordonnés”) (Würm-Holocene). d - Uncemented alluvial cones mostly consisting of limestone clasts (Würm-Holocene). e - Terraced alluvial deposits composed of clasts of basement rocks (Riss?). f - Tightly cemented and dismembered alluvial cones mostly made up of gelifraction limestone clasts (Riss?). g - Cuccuru ’e Flores Conglomerate: polymict, chaotic and thick-bedded breccia and stratified sandstone (middle Eocene). h - Siniscola Marl: grey and grey-yellow marl and, in the upper part, alternating marl/marly limestone with ammonites and very abundant radiolarians and sponge spicules (late Valanginian). i - Schiriddè Limestone: light-brown cherty limestone and limestone with marly interbeds, containing ammonites, radiolarians, sponge spicules and calpionellids (early Valanginian). j - Monte Bardia Limestone: thick-bedded to massive white limestone in places bioconstructed, with corals, nerineids, etc. (early Tithonian - late Berriasian). k - S’Adde Limestone: light-brown to grey fine-grained, well-bedded limestone, condensed with hardgrounds near the base, cherty in the upper part, with ammonites and belemnites in the uppermost part (latest Bathonian - earliest Tithonian). l - Dorgali Formation: well bedded quartz-arenitic and locally ooidal brown dolostone (middle-late Bathonian). m - Crystalline basement (phyllite, micaschist, paragneiss, quartzite, etc.) (Palaeozoic). n - Fault. o - Attitude of beds and schistosity planes. p - Limits of slumped masses of Jurassic formations (Quaternary). q - Concave-upward slip surfaces delimiting rotational slumps (Quaternary). r - Edge of fluvial terrace. s - Quarry. A-A’ Trace of the geological section of Fig. 2. (extracted from Bottini et al., 2018).