Novixitus quadripartitus, Dumitrica & Dieni & Massari, 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 : 151-152

Novixitus quadripartitus n. sp.

Figs. 16a, b, n ,?m

1981 Novixitus sp. – Kanie et al., pl. 1, fig. 17.

1982 Xitus sp. – Okamura & Uto, pl. 5, figs. 4, 5.

1995 Xitus sp. aff. X. spicularius (Aliev) – Baumgartner et al., p. 646, pl. 3295, fig. 3, non 1, 2, 4, 5.

2014 Xitus sp. – Robertson et al., p. 12, Fig. 10 (B), 6.

2017 Pseudoxitus (?) sp. – Xu & Luo, Fig. 8E, F .

Description. Shell large, cylindro-conical consisting of five to six segments separated by three deep constrictions. Cephalis and thorax form a usually smooth conical proximal part. Cephalis smooth, poreless or with very small, almost indistinct pores, with or without a small apical horn. Thorax is a truncate cone with dense and small circular pores and a beginning of some nodes at its base. Collar boundary marked by a shallow constriction result- ed by the widening of the base of thorax and by the increase of thoracic pores. Abdomen much larger, with a row of circumferential nodes and also a beginning of some additional nodes. Nodes usually elongate on longitudinal direction and interconnected by radially disposed interporal bars. Lumbar boundary marked by a change in outline due to the development of abdominal tubercles and appearance of larger abdominal pores. Next segments increase very slowly in diameter so that the postabdominal part is virtually subcylindrical. First postabdominal segment almost as high as abdomen and a little larger in diameter than it, resembling the abdomen in surface structure but having two rows of tubercles disposed one under the other so that some of them may unite giving rise to longitudinally elongated tubercles. First postlumbar intersegmental boundary very deep with very small tubercles along it. Second postabdominal segment as high as the previous one and a little larger in diameter. It bears a row of circumferential tubercles and is separat- ed from the previous segment by a deep intersegmental constriction with very small tubercles. Distal end of shell bearing one or two rows of big tubercles followed by a row of small intersegmental tubercles. A narrow cylindrical segment with thin wall and a circle of small tubercles may develop to close the building of complete shell.

Studied material. Two specimens in samples OZ 834 and OZ 836; other specimens are in the synonymy list.

Holotype. Fig. 16a , coll. MGP-PD, stub PD120 -OZ836- R08-02 .

Paratype. Fig. 16b , coll. MGP-PD, stub PD120 - OZ834- R09-06 .

Dimensions. Total length of shell with 5 segments 228- 260 µm, maximum diameter of the last segment 134-154 µm, of abdomen 99-112 µm.

Etymology. From the Latin quadri – related to four, and partitus = divided, because the shell is divided into four parts by three deep constrictions.

Remarks. The specimen from fig. 16n, which has only 4 segments but the characteristic abdomen with two rows of tubercles, is considered an incomplete specimen, fact suggested by the ragged distal end. The species illustrated by Kanie et al. (1981, pl. 1, fig. 17) is perfectly similar to this new species which differs from Xitus spicularius (Aliev) by being much shorter and having some segments with two rows of tubercles and no horn. From Xitus normalis (Wu and Li, 1982), that has also 5 segments, it differs by not having all segments with only one circumferential row of tubercles.

Occurrence. Reported also in Japan, Oman and in the Valanginian of Svinița section, Romania (see synonymy).

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.

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. 8. a - Becus coronatus Dumitrică n. sp., OZ839. b-f1, j - Becus triangulocentrum Dumitrică, b - OZ836; c - same, lateral view, d - OZ836. e, f - OZ825, f1 - lateral view of fig. f. g - Alievium regulare (Wu & Li), OZ836. h, i, k, l - Alievium rotundum Dumitrică n. sp.: h, specimen destroyed showing internal structure, OZ836; i - OZ836, k, l - holotype, OZ834. m - Alievium incomptum Dumitrică n. sp., OZ836. n - Godia (?) lenticulata Dumitrică n. sp., OZ834. o - Godia (?) lens Dumitrică n. sp., OZ825. p - Alievium eurasicum Dumitrică n. sp., OZ825. r - Microsandwichia plana (Hori), OZ834. s, t - Spumellarian gen. et sp. indet., OZ834. figs. c, e-h, k, m, r, t x250, figs. a, b, d, i, j, l, p, s x300; figs. n, o, t x400.