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. B

Figs. 15N ; 16B

Number of specimens:>10

Diagnosis. Segminate P 1 element with subsymmetrical, posteriorly rounded and anteriorly tapered basal cavity. Large terminal, subtriangular, recurved cusp. Anterior process bearing a few denticles only.

Description. Te element shows a large cusp at the posterior end. In lateral view, the large, recurved, subtriangular cusp is about as high as the whole unit is long. An anterior process with two or three small upright to reclined denticles is present. Te lower margin is straight to concave. In aboral view, the subsymmetrical basal cavity is sub-rounded at the posterior margin and tapers towards the anterior end.

Remarks. Tese P 1 elements most closely resemble Discretella aff. discreta , but differ in having a much shorter anterior process and recurved denticles. Tey also bear some superficial resemblance with the P 1 elements of the Spathian–Anisian genus Cornudina , but differ in their conformation of the basal cavity. Urdyella unicorna n. gen. n. sp. usually has a much thinner and larger, sickleshaped cusp and a rounded basal cavity.

Because of the absence of a posterior process, some elements, especially arched ones, resemble homologous elements of Guangxidella and could possibly be assigned to that genus, but their basal cavity do not match those of Guangxidella and resemble instead that of Discretella aff. discreta , hence we tentatively retain them within Discretella .

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

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.

Discretella ? n. sp. D

Fig. 26 AB, AC.

2014 Genus gen. indet. D; Maekawa & Igo in Shigeta et al., p. 269, figs. 193.8–9.

Holotype. Specimen illustrated in Fig. 26 AB.

Number of specimens:>20

Diagnosis. Same P 1 element as in Discretella ? n. sp. C except it bears no anterior process.

Remarks. As for Discretella ? n. sp. B and C (see above) the generic assignment of these forms is uncertain and may deserve a new genus name, especially given that the present taxa bear neither posterior nor anterior denticles.

Occurrence. Laren road cut, Luolou Formation, Smithian age, Nanpanjiang basin, South China (this paper); North-eastern Vietnam, Novispathodu s ex gr. waageni Zone between Flemingites rursiradiatus beds and Urdyceras tulongensis beds and within the Owenites koeneni beds, Bac Tuy Formation ( Shigeta et al., 2014).

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 Neogondolellinae, Novispathodinae and Mullerinae from Shanggang and Youping cascade. Magnification is ×80.The scale bar is 400 μm. All elements are considered to be P1 elements if not specifically identified otherwise. A, F, M Discretella? n. sp. C; A YC16,PIMUZ 39115; F YC16, PIMUZ 39116; M SHA342C, PIMUZ 39117. B Discretella? n. sp. B;YC16, PIMUZ 39113. C Discretella aff.discreta (MÜller);YC22,PIMUZ 39106. D, S Discretella discreta (MÜller); D YC16, PIMUZ 39110; S SHA304C, PIMUZ 39111. E Novispathodus ex gr. abruptus (Orchard);YC41, PIMUZ 39225. G–I, K, L, N, O Discretella pseudodieneri n. sp.; G YC16, PIMUZ 39124; H YC25, PIMUZ 39125; I SHA304C,PIMUZ 39126; K YC22, PIMUZ 39127,L YC25, PIMUZ 39128; N SHA304C,PIMUZ 39129; O SHA343C,PIMUZ SQL54979. J Guangxidella bransoni (MÜller);YC16, PIMUZ 39140. P–R Neospathodus bevelledi n. sp.; P SHA 304C,PIMUZ 39178; Q SHA333C, PIMUZ 39179; R YC12, PIMUZ 39180

Fig. 26 Cornudininae 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–W Urdyella unicorna n. gen. n. sp.; A LAR225, PIMUZ 39345; B LAR225, PIMUZ 39346;C LAR229, PIMUZ 39347; D LAR227, PIMUZ 39348;E LAR229,PIMUZ 39349; F LAR229,PIMUZ 39350; G LAR225,PIMUZ 39351; H LAR229,PIMUZ 39352; I QIA123, PIMUZ 39353; J LAR227,PIMUZ 39354; K QIA123, PIMUZ 39355; L QIA123, PIMUZ 39356; M LAR227,PIMUZ 39357; N LAR225, PIMUZ 39358; O QIA120, PIMUZ 39359; P LAR225, PIMUZ 39360; Q QIA121, PIMUZ 39361; R LAR232, PIMUZ 39362; S LAR232, PIMUZ 39363; T QIA124,PIMUZ 39364; U LAR232, PIMUZ 39365; V QIA123, PIMUZ 39366; W SHA341, PIMUZ 39367.X-AA Urdyella tridenta n. gen. n. sp.; X LAR227, PIMUZ 39341; Y LAR227, PIMUZ 39342; Z LAR227, PIMUZ 39343; AA LAR227, PIMUZ 39344.AB, AC Discretella? n. sp. D; AB QIA124, PIMUZ 39118; AC QIA123, PIMUZ 39119. AD Neostrachanognathus n. sp. A; LAR232, PIMUZ 39183. AE Urdyella n. sp. A; LAR232, PIMUZ 39340