Protopanderodus leonardii Serpagli, 1974

Zhen, Yong Yi, Percival, Ian G. & Webby, Barry D., 2003, Early Ordovician Conodonts from Far Western New South Wales, Australia, Records of the Australian Museum 55 (2), pp. 169-220 : 207

Protopanderodus leonardii Serpagli, 1974

Fig. 22L–R

Protopanderodus leonardii Serpagli, 1974: 77 , pl. 16, figs. 1a– 4c, pl. 27, figs. 12–16, text-fig. 6.

Protopanderodus leonardii .–Zhen et al., in press: pl. 4, figs. 23, 24 (cum syn.).

Material. Six specimens (1 Sa, 3 Sb, 2 Sc) from the Tabita Formation at Mount Arrowsmith.

Remarks. This species differs from P. gradatus mainly in having sharp anterior margins. Serpagli (1974) initially recognized a trimembrate apparatus consisting of a symmetrical bicostate Sa, asymmetrical bicostate Sb, and asymmetrical acostate Sc elements . However, his illustrations depict two distinct forms of elements. The holotype ( Serpagli, 1974, pl. 27, fig. 15) and a paratype ( Serpagli, 1974, pl. 27, fig. 14) have an extremely short base, and are interpreted as P elements . The other three figured paratypes have a relatively longer base supporting a more or less erect cusp, and represent a symmetry transition series of S elements .

This species is uncommon at Mount Arrowsmith. Three types of S elements were recovered, but no P elements have been recognized. The Sa element is symmetrical or nearly so with a posterolateral costa on each side ( Fig. 22L ). The Sb element is similar to the Sa, but asymmetrical, with cusp curved inwards and slightly twisted ( Fig. 22M,N ). The Sc element is asymmetrical with sharp anterior and posterior margins, and a more expanded base; it has a posterolateral costa on each side, and a thin inner-laterally curved anterior edge ( Fig. 22 O–R ).

Figures

Fig. 22. A–K, Protopanderodus gradatus Serpagli, 1974: A, Sa element, AMF120436, M/A11-1, posterolateral view; B, Sd element, AMF120437, C1612, outer lateral view; C,D, Sb element, AMF120438, C1612, C, inner lateral view, D, outer lateral view; E,F, Sc element,AMF120439, C1612, E, inner lateral view, F, outer lateral view; G, Sd element, AMF120440, C1612, outer lateral view; H–J, Sa element,AMF120441,Y4–2, H,I, lateral views, J, close up showing the fine striae; K, Sd element,AMF120442, C1612, inner lateral view. L–R, Protopanderodus leonardii Serpagli, 1974: L, Sa element,AMF120443, M/A11-3, lateral view; M, Sb element,AMF120444,