Novispathodus praebrevissimus, Leu & Bucher & Vennemann & Bagherpour & Ji & Brosse & Goudemand, 2022

Leu, Marc, Bucher, Hugo, Vennemann, Torsten, Bagherpour, Borhan, Ji, Cheng, Brosse, Morgane & Goudemand, Nicolas, 2022, A Unitary Association-based conodont biozonation of the Smithian-Spathian boundary (Early Triassic) and associated biotic crisis from South China, Swiss Journal of Palaeontology (19) 141 (1), pp. 1-61 : 36-37

Novispathodus praebrevissimus n. sp.

Figs. 17V ; 18A–D, F, J–N, O ?, P?, Q, S, T; 19R

1984 Neospathodus sp. aff. triangularis Bender ; Hatleberg & Clark, pl. 3, fig. 16

2014 Icriospathodus? zaksi (Buryi) ; Maekawa & Igo in Shigeta et al., fig. 192, nr. 10–13 (only).

2015 Novispathodus brevissimus (Orchard) ; Chen et al., p. 111, fig. 7.8.

2019 Novispathodus pingdingshanensis (Zhao & Orchard) ; Chen et al., fig. 3 nr. 5, 9 (only) fig. 5, nr. 6 (only).

2019 Novispathodus pingdingshanensis (Zhao & Orchard) ; Liu et al., p. 13, pl. 3, fig. 7 (only).

Etymology: According to its presumed relationship as a predecessor of Nv. brevissimus .

Holotype: specimen illustrated in fig. 24R

Paratype: specimen illustrated in fig. 24Q

Type locality: Lilong cliff, Luolou formation, Guangxi Province, China.

Type level: Luolou Formation, within latest Smithian black shales. Present in UAZ 5 which corresponds to the peak of the positive δ 13 Ccarb excursion and the Xenoceltites / Glyptophiceras beds.

Number of specimens.> 40.

Diagnosis. Short robust segminate P 1 element. Large rounded-to-sub-rounded basal cavity. Posterior margin often slightly concave. Small, largely fused denticles. Groove from basal pit to anterior end.

Description. Te segminate P 1 element shows a very large rounded to sub-rounded basal cavity in the posterior half of the element. A very deep basal groove is present from the basal pit to the anterior end of the lower margin. Te carina is relatively high with numerous small, fused denticles. Te cusp is undistinguishable. Te posterior lateral margin (posteriormost edge between basal cavity and last denticle) is slightly to strongly curved. Sometimes, the height of the posteriormost denticles is gradually but rapidly decreasing. In lateral view, the denticles tend to be radiating or recurved.

Remarks. Tis species is thought to be intermediate between Nv. pingdingshanensis and Nv. brevissimus . Te P 1 element of this species is very similar to that of Nv. pingdingshanensis , but the basal cavity is much larger and rounded. In comparison to Nv. brevissimus , this species is usually smaller and has a relatively bigger and more rounded basal cavity. Furthermore, the carina is lower, with less numerous denticles. Te new species is distinguished from the similar Novispathodus shirokawai ( Maekawa et al., 2018) by reclined and less pointy denticles, a larger, rounded basal cavity and a less triangular shape in lateral view. Compared to Ic. zaksi , the P 1 element of this species is less robust and has a relatively higher carina. Ns. expansus (Zhao & Orchard) has a very similar morphology to Nv. praebrevissimus n. sp., but it has a distinct conspicuous thickening in the middle part of its unit. Some specimens of Nv. praebrevissimus n. sp.

( Fig. 18L, O and P ) show a bulbous thickening in the posterior part of the carina but never as pronounced as in Ns. expansus .

Occurrence. Spitsbergen, Botneheia Formation ( Hatleberg & Clark, 1984). South China, Nanpanjiang basin: Jiarong, southern Guizhou ( Chen et al., 2015). Luolou Formation, within latest Smithian black shales. Present in UAZ 5 which corresponds to the peak of the positive δ 13 Ccarb excursion and the Xenoceltites / Glyptophiceras beds, Guangxi, South China (this study). Oman (Leu et al., submitted).

Figures

Fig. 17 (See legend on previous page.)

Fig. 18 (See legend on previous page.)