Novixitus robustus Wu, 1993

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 : 152

Novixitus robustus Wu, 1993

Figs. 16c , g-i, k, l

1981 Xitus spicularius (Aliev) – Schaaf, p. 440, pl. 5, figs. 12a, b; pl. 19, figs. 2a, b.

1982 Novixitus sp. (pars) – Okamura & Uto, pl. 2, fig. 8, non 7, 9.

1983 Novixitus (?) maclaughlini Pessagno – Origlia-Devos, p. 211, pl. 25, figs. 2, 3.

1984 Xitus sp. cf. X. spicularius Aliev – Baumgartner, p. 792, figs. 16, 17.

1989 Xitus sp. cf. X. spicularius (Aliev) – Matsuoka, fig. 2. 2.

1992 Xitus spicularius (Aliev) – Steiger, p. 89, pl. 26, figs. 9?, 10, 11.

1992 Xitus spicularius (Aliev) – Ozvoldova & Petercakova, pl. 4, fig. 6.

1993 Xitus robustus Wu, p. 127, pl. 4, fig. 10.

1994 Xitus clava (Parona) – O’Dogherty, p. 124, pl. 11, figs. 1-8.

1995 Xitus sp. aff. X. spicularius (Aliev) – Baumgartner et al., p. 646, pl. 3295 (p. 647), fig. 2, non 1, 3-5.

1995 Xitus sp. cf. X. spicularius (Aliev) – Takahashi & Ishii, pl. 3, fig. 13.

1997 Xitus robustus Wu – Dumitrică et al., p. 57, pl. 13, figs. 4?, 10, 11.

2014 Xitus robustus Wu – Robertson et al., fig. 10(B), 21. 2017 Xitus robustus Wu – Xu & Luo, fig. G-K.

Description. Shell robust, wide conical consisting commonly of five segments. Cephalis and thorax form a short conical body with a practically imperforated and smooth hemispherical cephalis bearing or not an extremely short apical horn. Thorax truncate conical with small circular pores and bearing 3-4 tubercles visible at its lower part on half the perimeter. Abdomen and the following two postabdominal segments much larger and forming a robust truncate conical body. Each segment has one circumferential row of big tubercles. Similar rows, but with smaller tubercles, are also developed on the intersegmental suture zone. Tubercles are usually interconnected with the neighbouring ones by ribs giving the surface a stellate ornamentation. Fifth segment wide open. The sixth segment is very rarely preserved ( Fig. 16h ); it is thinner walled, inverted truncate cone-shaped and has a circumferential row of five tubercles on its middle part.

Remarks. The specimens illustrated by Steiger (1992) as Xitus spicularius from the Tithonian-lower Valanginian differ from the specimens from S’Ozzastru section by being less wide conical. Similar specimens, but somehow wider conical, have been illustrated by O’Dogherty (1994) as Xitus clava (Parona) from the lower Aptian, but do not belong to this species, as demonstrated later by Dumitrică (in Dumitrică et al., 1997, p. 58, pl. 14, figs. 4, 5), when he erected the genus Clavaxitus for Parona’s species.

Studied material. Many specimens.

Range and occurrence. Valanginian to Aptian so far as known in Tethys.

Figures

Fig. 16 a, b, m, n - Novixitus quadripartitus Dumitrică n. sp.: a - holotype, OZ836. b - paratype, OZ834. c?, g-i, k, l, - Novixitus robustus Wu, OZ825. d - Pseudoxitus wui Dumitrică n. sp., holotype, OZ836. e - Xitus vermiculatus (Renz), OZ838. f, j - Pseudoxitus laguncula Dumitrică, OZ836. i - OZ836, k - basal view, OZ839. All figures x250.