Hemicryptocapsa, Tan, 1927 emend. Dumitrica, 1970

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 : 119-120

Hemicryptocapsa (?) bellireticulum (Wu & Li, 1982) Figs. 10 a-c1

?1927 Theocapsa curata Tan , p. 47, pl. 8. Figs. 50, 51.

1982 Zhamoidellum bellireticulum Wu & Li , p. 67, pl. 1, figs. 12, 13.

Description. Test three segmented. Cephalothorax bell-shaped with only the lowermost part of thorax included in the abdominal cavity. Cephalis very small, hemispherical externally, without apical horn, practically poreless or with very rare and very small pores, its collar suture marked by a row of pores and an evident constriction due to the fast increase of the diameter of thorax. Thorax much larger than cephalis, cylindrical and roughsurfaced, with ornamentation resulting from filling of a porous structure of which only rarely pores are visible. Its lower part is included in abdominal cavity and its apertural border bears three diverging needle shaped spines. Sutural pore very narrow, almost indistinct in the vicinity of thorax. Abdomen ovoid or cordate with acute part distally positioned. Distal end with a very narrow circular larger pore with protruding rim that could be an aperture ( Fig. 10 c 1 ). Abdominal wall thick perforated by numerous and irregularly disposed circular or subcircular pores. Its surface wrinkled resulted from an irregular network of sharp crests of different lengths and positions with pyramidal elevation at junctions.

Studied material. Seven photographed specimens in coll. MGP-PD, stub PD120, samples: OZ824 (stub PD120- OZ824-R13-15, R13-26, R13-27, R13-29; OZ825 (stub PD120-OZ825-R12-23), OZ836 (stub PD120-OZ836- R07-10), and OZ838 (stub PD120-OZ838-R04-06).

Dimensions. Length of shell 172-180 μm, of cephalothorax outside abdomen 40-48 μm, of abdomen 124-132 μm, diameter of cephalothorax 52-56 μm, of abdomen 124- 132 μm.

Remarks. Almost all illustrated specimens resemble the holotype. The specimen with elongated abdomen ( Fig. 10c ) is the only one with such a morphology, suggesting that it could be an anomaly. The superficial abdominal ornamentation of this species resembles somehow that of the lower Aptian Cryptamphorella gilkeyi Dumitrică 1972 , from which it differs in having the superficial polygonal areas partly open on at least one side and especially in having the cephalothorax very little hidden in abdominal cavity and well separated from the latter, and in not having a sutural pore and distal aperture. The species is questionably assigned to the genus Hemicryptocapsa because it has no relict postabdominal chamber.

By its shape, this species is very close to Theocapsa curata Tan (1927, pl. 8, figs. 50, 51) from which it only differs by having much denser pores and a different superficial ornamentation.

Range and occurrence. Upper Valanginian of Sardinia, and in Tibet, in a block of the Zongzhuo Formation (Wu & Li, 1982) .

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. 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).