Ocellicapsa ruthae 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 : 133-134

Ocellicapsa ruthae Dumitrică nov. sp.

Figs. 12 i-o

1982 Sethocapsa sp. – Okamura & Uto, pl. 3, fig. 12.

1982 Tricolocapsa sp. – Okamura & Uto, pl. 9, figs. 1a-b. 1982 unnamed nassellarinid C – Wu & Li, pl. 2, fig. 16.

1989 Sethocapsa kaminogoensis Aita – Tumanda, p. 39, pl. 4, figs. 13, 14;? pl. 10, fig. I12

1994 Sethocapsa sp. aff. kaminogoensis Aita – Jud, p. 104, pl. 19, fig. 15; pl. 20, figs. 1, 2.

1994 Sethocapsa kaminogoensis Aita – Goričan, p. 87, pl. 15, fig. 7.

2003 Hiscocapsa kaminogoensis (Aita) – Zyabrev et al., fig. 3.25.

2009 Hiscocapsa kaminogoensis (Aita) – Ishii et al., pl. 20, fig. 11.

2017 Hiscocapsa sp. aff. H. kaminogoensis (Aita) – Xu & Luo, fig. 5H.

Description. Shell tetracyrtid, conical and tuberculate. Cephalis conical and smooth with rounded apex and imperforate. Thorax about as long as cephalis but much wider. Its wall perforated by very small and irregularly distributed pores, and its distal part constricted and plunged in the abdominal cavity ( Fig. 12n ). Collar boundary usually marked by a shallow constriction and by the presence of pores. Shell has usually about four or five tubercles on half the perimeter. Abdomen higher and much wider than thorax, with wall perforated by circular pores wider than those of thorax, and surface covered with a circumferential row of tubercles. Lumbar boundary marked by an evident constriction resulted from the fast increase of the diameter of abdomen. Postabdominal chamber globular and much wider that the other segments. It bears numerous tubercles arranged irregularly and commonly interconnected at the surface of the shell by ribs. Pores dense, circular, arranged in irregular rows of different orientations. At the boundary with abdomen the postabdominal chamber bears a circumferential row of large ocelli open in lateral direction. Their number varies from 6 to 8 on half the perimeter. Distal part of the abdomen rather flat or convex and closed.

Studied material. 14 figured specimens from samples OZ824, OZ825, OZ834, OZ836, OZ837 and OZ838.

Holotype. Fig. 12i , coll. MGP-PD, stub PD120 -OZ837- R06-22 .

Paratype. Fig. 12l , coll. MGP-PD, stub PD120 - OZ824- R13-22 .

Dimensions. Total length 153-174 µm, length of the first three chambers 89-90 µm, of cephalis 23-24 µm, diameter of base of cephalis 26-28 µm, of thorax 44-48 µm, of abdomen 70-84 µm, of postabdominal segment 106-140 µm,

Etymology. The species is dedicated to Ruth Dumitrică- Jud who first described the morphology of this species and remarked that, in spite of its resemblance with Sethocapsa kaminogoensis Aita, 1986 , it differs from this taxon by the lateral opening of the large pores (= ocelli) between the abdomen and the postabdominal segment.

Remarks. Ocellicapsa ruthae nov. sp. is very similar to O. kaminogoensis (Aita) by having a tuberculate skeleton but differs by having the ocelli opened in lateral directions, so that they are well visible in lateral view, whereas in O. kaminogoensis they are visible in apical or obliquely apical view (see Aita & Okada, 1986, pl. 5, figs. 3, 6; Takahashi & Ishii, 1995, pl. 2, fig. 26), as in Crococapsa uterculus (Parona, 1890) . It is strange that Jud ( 1994), who studied also the Berriasian radiolarian fauna from Breggia, type locality of O. kaminogoensis , did not illustrate specimens of this species. The three specimens illustrated and considered by her as having affinities with this species, came: one from the upper Valanginian of the Fiume Bosso section, and two from the Barremian of the Presale and Fiume Bosso sections, respectively. Even the specimen illustrated by Goričan ( 1994) as O. kaminogoensis , and that is in fact O. ruthae , comes from the upper Valanginian-Hauterivian of her zonation. This situation could have a single explanation: the sample in which Aita & Okada founded their species O. kaminogoensis came from a level of the Berriasian lower than that from which Jud collected her Berriasian fauna. Therefore, O. kaminogoensis could be considered as the forerunner of O. ruthae and the transition between the two species could have taken place during the late Berriasian or earliest Valanginian.

Range. Valanginian to Barremian so far as known.

Figures

Fig. 12 b - Crococapsa cf. horokanaiensis (Kawabata), OZ834. a, c, d - Crococapsa zweilii (Jud): a, OZ826; c, OZ836; d, OZ825. e-h - Crococapsa uterculus (Parona): e, f, h - OZ834, g - OZ825. i-o - Ocellicapsa ruthae Dumitrică n. sp.: i - OZ837, j - OZ837, k - OZ836, i - OZ834, m - OZ824, n - OZ838, n1 - detail of cephalothoracic body, arrow shows the place of very small pores at the boundary between the two parts of cephalic cavity, o - OZ825. p, r, t, v - Squinabolum elegans Dumitrică n. sp.: p - OZ824, r - OZ826, t - OZ836, s - Amphipyndax zyabrevi Dumitrică n. sp. - OZ825. u - Campanomitra pulchella (Rüst), OZ836. v - OZ834. w, x - Archaeodictyomitra inflata Dumitrică n. sp.: w - OZ839, x - OZ834. Figs. a, c-h, u x250, all the others x300.