Dapsilodus viruensis ( Fåhraeus, 1966 )

Zhen, Yong Yi, 2011, Middle to Late Ordovician (Darriwilian-Sandbian) Conodonts from the Dawangou Section, Kalpin Area of the Tarim Basin, Northwestern China, Records of the Australian Museum 63 (3), pp. 203-266 : 221-222

Dapsilodus viruensis ( Fåhraeus, 1966)

Fig. 9A ,?B–C

Acodus viruensis Fåhraeus, 1966: 12 , pl. 2, fig. 2a–b, text-fig. 2A.

Acontiodus sulcatus Fåhraeus, 1966: 17 , pl. 2, fig. 6a–b, text-fig. 2F.

Acodus ? mutatus (Branson & Mehl) .– Löfgren, 1978: 44, pl. 2, figs 9–21 (cum syn.); Zeng et al., 1983: pl. 12, figs 39–40.

Dapsilodus mutatus (Branson & Mehl) .– An, 1987: 142, partim only pl. 4, figs 14, 17–18, 22–23, 27; An & Zheng, 1990: 164, pl. 4, figs?1, 2–5; Stouge & Bagnoli, 1990: 14, pl. 9, figs 19, 26–27; Gao, 1991: 130, pl. 12, figs 10, 17; Ding et al. in Wang, 1993: pl. 15, figs?22, 23–24, 26; Armstrong, 1997: 786, pl. 5–8,?3–4; Ferretti & Serpagli, 1999: 230, pl. 3, figs 20–23; Wang, 2001: 351, pl. 2, figs 8–9 (cum syn.).

Dapsilodus striatus Chen & Zhang, 1984b: 126 , 134, pl.1, figs 17–20; Duan, 1990: pl. 3, fig. 1.

Dapsilodus viruensis (Fåhraeus) .–Zhang, 1998b: 58–59, pl. 4, figs 1–6 (cum syn.); Rasmussen, 2001: 67–68, pl. 4, figs 15–17 (cum syn.); Zhen et al., 2009a: 142, fig. 4A–O (cum syn.).

Material. 74 specimens from 17 samples (see Tables 1–2).

Remarks. Löfgren (1978), An (1987) and Stouge & Bagnoli (1990) regarded Acodus viruensis Fåhraeus, 1966 as a junior synonym of Belodus (?) mutatus Branson & Mehl, 1933 , whereas others, including Zhang (1998b), Ferretti & Serpagli (1999) and Rasmussen (2001), considered them as separate species. The taxonomic position of Belodus (?) mutatus has been discussed for many decades, and it remains as a poorly known species until its species apparatus and constituent elements are revised according to the multielement species concept. In particular, Rasmussen (2001, p. 68) pointed out that the original description of Belodus (?) mutatus by Branson & Mehl (1933, p. 126) indicated the presence of “one or two minute denticles” on “the posterior end” in some of the specimens from the basal Maquoketa Shale of Missouri. However, this taxonomically important character has not been observed in the type specimens (holotype and other topotype material) and from any of the Swedish and Chinese material previously assigned to D. mutatus , and more likely the Chinese specimens belong to D. viruensis (see Zhang, 1998b).

Figures

Figure 9. A–C, Dapsilodus viruensis (Fåhraeus, 1966). A, Sc element, NIGP 152896, Nj375, outer lateral view (IY159-024). B–C, Sa element; B, NIGP 152897, Nj375, lateral view (IY159-025), tentatively assigned to this species; C, NIGP 152898, Nj375, lateral view (IY159-026). D–O, Scabbardella altipes (Henningsmoen, 1948). D–E, long-based acodiform element; D, NIGP 152899, Nj378, outer lateral view (IY153-016); E, NIGP 152900, Nj403, outer lateral view (IY161-021). F–G, medium-based acodiform element; F, NIGP 152901, Nj297, outer lateral view (IY159-012); G, NIGP 152902, AFT-X-K13/13, outer lateral view (IY167-002). H–O, asymmetrical distacodiform element; H, NIGP 152903, Nj376, outer lateral view (IY159-029); I–K, NIGP 152904, Nj378, I, outer lateral view (IY160- 017), J, inner lateral view (IY160-017), K, basal view (IY160-020); L–N, NIGP 152905, Nj379, L, upper view, close up of cross section of the cusp (IY160-035), M, inner lateral view (IY160-036), N, upper view (IY160-034); O, NIGP 152906, Nj379, outer lateral view (IY160-033). Scale bars 100 µm, unless otherwise indicated.