Discretella, Orchard, 2005

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 : 46-47

Discretella ? n. sp. C

Figs. 15O ; 16A, F, M .

1989 Cratognathodus sp. A ; Tang, p. 405, pl. 32, fig. 8.

2013 Neospathodus? peculiaris Sweet ; Yan et al., p. 516, fig. 6M.

2014 Discretella sp. indet. A; Maekawa & Igo in Shigeta et al., p. 202–207, fig. 151.1–151.12, 151.16–151.18 (only).

2014 Genus gen. indet. D; Maekawa & Igo in Shigeta et al., p. 269, figs. 193.10–193.12.

Number of specimens:>10

Diagnosis and description. Same as Discretella ? n. sp. B except that a very small posterior process without denticle is always present and the laterally twisted basal cavity tapers at both ends. Te anterior process may bear up to 5 denticles.

Remarks. Te P 1 elements of this species are very similar to those of the coeval Discretella ? n. sp. B and both species may be conspecific although the presence of the incipient posterior process and the geometry of the basal cavity suggest they correspond at least to two different morphotypes, possibly due to sexual dimorphism. Tey also share strong similarities with the P 1 of Discretella ? n. sp. D, which may be a descendant of Discretella ? n. sp. B via reduction/loss of the anterior process, forms like, Fig. 16M (and figs. 193.10–193.12 of Maekawa and Igo in Shigeta et al., 2014) that bear only one or two anterior denticles being intermediary. Te relationship with Discretella sp. indet. A Maekawa & Igo is unclear but the P 1 of the latter is almost identical, except that the incipient posterior process bears a small triangular denticle. Maekawa & Igo noted also that the anterior process of the P 1 element of Discretella sp. indet. A (Maekawa & Igo) may also have been reduced over time. Conversely, Discretella robustus ( Wang & Wang, 1976) , which share a similar recurved cusp and a sigmoidal profile in lower view, has more developed anterior and posterior processes and may be their forerunner.

Occurrence. South China: Luolou, Smithian age, Laren, Guangxi.

Figures

Fig. 15 Neogondolellinae and Mullerinae from Qiakong, Laren and Shanggang. Magnification is ×80.The scale bar is 400 μm. All elements are considered to be P1 elements if not specifically identified otherwise. A, D Neospathodus bevelledi n. sp.; A SHA333,PIMUZ 39176; D, SHA332, PIMUZ 39177. B, J Discretella aff. discreta (MÜller); B SHA304, PIMUZ 39104; J SHA334,PIMUZ 39105. C, L Discretella discreta (MÜller); C SHA334, PIMUZ 39107; L SHA332, PIMUZ 39108. E Guangxidella bransoni (MÜller); SHA304, PIMUZ 39139.F, H, K, M, P Discretella pseudodieneri n. sp.; F QIA124, PIMUZ 39120; H QIA124,PIMUZ SQL54990; K QIA121, PIMUZ 39121; M QIA120, PIMUZ 39122; P LAR232, PIMUZ 39123. G Discretella cf. discreta (MÜller); QIA120, PIMUZ 39109.I sp. indet.; QIA120, PIMUZ 39294. N Discretella? n. sp. B; LAR232, PIMUZ 39112.O Discretella? n. sp. C; SHA342,PIMUZ 39114

Fig. 16 (See legend on previous page.)