Yuan et al.—Permian conodont taxonomy and biostratigraphy in South China


Holotype.—NIGP121709, from the Wuchiaping Formation, Sichuan Province, China (Mei et al., 1994a, pl. 1, fig. 18).


Original diagnosis.—A species of Clarkina characterized by a P1 element with a blunt, but rounded posterior platform termi- nation; width of platform increasing gradually until the middle; cusp terminally located, erect and larger than the denticles on the posterior half of the element; posteriormost denticle generally small; denticles increasing in size anterior (except the distal two smaller denticles) and discrete posteriorly; furrows moderately developed and smooth; lateral margins slightly upturned at the widest point; platform narrowing sharply on the anterior half and continuing near the anterior end (Mei et al., 1994a, p. 134).


Emended diagnosis.—A species of Clarkina characterized by a P1 element with a bluntly rounded to squarely rounded posterior end of platform. Width of platform slightly increasing from posterior end to middle part where the widest point occurs, then narrows gradually, until it narrows sharply in the anterior 1/4 or 1/3. Inner lateral margin is straight in most individuals, and lateral margins of some specimens are nearly parallel. Cusp is erect (adults) to slightly reclined (juveniles), terminal, and larger than almost all other denticles on the carina, and sometimes fused with the posteriormost denticle. Posteriormost denticle is generally small, then denticles increase in size anteriorly except the distal two or three denticles, and posterior denticles are more discrete than anterior denticles. Denticles on the carina are nearly equal in height in many specimens. Furrows are moder- ately developed and smooth.


Remarks.—Mei et al. (1994a) established this species at the Dukou Section, and assigned the holotype from sample L-127 (Fig. 4.18, 4.19). However, Mei considered this holotype as an advanced form, and the specimen (Fig. 4.22, 4.23) is a typical form (S.L. Mei, personal communication, 2012). This species can be distinguished from Clarkina postbitteri postbitteri by a relatively wide platform, more closely spaced denticles on the carina as well as usual absence of a gap between the cusp and the posteriormost denticle. Gerontic individuals from strati- graphically younger intervals tend to have a more fused middle carina and a relatively wider platform than those of specimens from stratigraphically older intervals, which are more similar to C. asymmetrica, and leads to difficulty in recognizing the boundary between the C. dukouensis Zone and C. asymmetrica Zone. Wang (2000) established a new species, Clarkina penglai-


tanensis, whose major characteristic is its high, nearly triangular outline platform with a downturned and truncated posterior end. However, this characteristic can be found in C. dukouensis populations (e.g., Fig. 4.26), and its paratypes have unfused, but closely spaced denticles on the carina, which is also a


1209


characteristic of C. dukouensis. Thus, those paratypes are here referred to C. dukouensis.


Clarkina asymmetrica Mei and Wardlaw in Mei et al., 1994a Figure 5.1–5.16


1991 1991


1994a 1995


Neogondolella guangyuanensis; Wang and Dong, pl. 3, fig. 1.


Neogondolella bitteri; Wang and Dong, pl. 1, figs. 14, 16.


?1998a Clarkina asymmetrica; Mei et al., pl. 5, fig. 10. 1998a Clarkina asymmetrica; Mei et al., pl. 9, figs. 8–15, pl. 10, fig. 13.


Clarkina niuzhuangensis; Kozur, pl. 5, fig. 19.


?2000 Clarkina penglaitanensis Wang, pl. 4, figs. 14, 15. ?2000 Clarkina sp. nov. A Wang, pl. 7, figs. 17, 18.


?2004 Clarkina postbitteri postbitteri; Wang and Xia, fig. 3A.


2004


?2004 2008 2008


2008 2010


Clarkina dukouensis;Wang and Xia, figs. 3I, 3Q. Clarkina asymmetrica;Wang and Xia, figs. 3K, 3L. Clarkina dukouensis; Zhang et al., pl. 2, figs. 9, 27–29.


Clarkina guangyuanensis; Zhang et al., pl. 2, fig. 19.


Clarkina asymmetrica; Zhang et al., p. 439, pl. 2, figs. 17, 30, pl. 3, figs. 1, 12, 13.


Clarkina asymmetrica; Shen and Mei, p. 153, figs. 3.8a–3.16b.


Holotype.—NIGP121706, from the Wuchiaping Formation, Sichuan Province, China (Mei et al., 1994a, pl. I, fig. 16).


Original diagnosis.—A species of Clarkina characterized by a P1 element with an obliquely squared posterior platform termi- nation; a moderate cusp; posterior three denticles much less fused than the middle portion of the carina, which becomes very fused in larger specimens; denticles increasing in size anteriorly; a small gap between the first posterior denticle and the cusp or the second posterior denticle or both; furrows shallow; platform margins only slightly upturned, with straight to slightly convex inner side and always more convex outer side. Platform extending for 2/3 to 3/4 length of element before narrowing; element bowed; anterior narrowing of the platform beginning on the inner side before the outer side, making it asymmetric in appearance (Mei et al., 1994a, p. 132).


Emended diagnosis.—A species of Clarkina characterized by a P1 element with an obliquely squared to squarely rounded pos- terior end of platform. Inner side of platform is straight to slightly convex, but outer side is always more convex, and they exhibit obvious narrowing in the anterior 1/4 or 1/3. Anterior narrowing of the platform on inner side is relatively late, but


Figure 4. (1–17) Clarkina postbitteri postbitteri Mei and Wardlaw in Mei et al., 1994b: (1) Holotype, NIGP123476, from sample LPD-115 at Penglaitan Section in Mei et al. (1994b); (2–17) from sample Bed 6k at Penglaitan Section, (2–9, 12–17) NIGP134595-134601, from Henderson et al. (2002), (10, 11) NIGP166064. (18–31) Clarkina dukouensis Mei and Wardlaw in Mei et al., 1994a: (18, 19) Holotype, NIGP121709, from sample L-127 at Dukou Section in Mei et al. (1994a); (20, 21) NIGP123496, from sample L-125 at Dukou Section in Mei et al. (1994b); (22, 23) NIGP123504, from sample Dg-27 at Nanjiang Section in Mei et al. (1994b); (24, 25) from sample Dg-27 at Nanjiang Section, NIGP166065; (26, 27) NIGP123472, from sample LPD-111 at Penglaitan Section in Mei et al. (1994b); (28–31) from sample LPD-111 at Penglaitan Section, NIGP166066, 166067.


Clarkina asymmetrica Mei and Wardlaw in Mei et al., p. 132, pl. 1, figs. 12, 15, 16.


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