Placoparina? dravidicus ( Reed, 1915 ), 1940

Fortey, Richard A., Wernette, Shelly J. & Hughes, Nigel C., 2022, Revision of F. R. C. Reed’s Ordovician trilobite types from Myanmar (Burma) and western Yunnan Province, China, Zootaxa 5162 (4), pp. 301-356 : 340

Placoparina? dravidicus ( Reed, 1915)

Fig. 13.2

1915 Cheirurus dravidicus ; Reed, p. 48, pl. 8, fig. 12.

Material. Holotype: pygidium from Lower Naungkangyi Beds (probable Darriwilian) at Man-shio, Fig. 13.2 ( Reed, 1915, pl. 8, fig. 12), GSI 11559.

Discussion. The species was described by Reed (1915) on the basis of one pygidium; a cast from the counterpart of the type specimen is illustrated here. Reed’s illustrations show the tips of the three pairs of pygidial spines. The anterior pair is not noticeably more strongly developed than the other two pairs, as it is in cheirurines, and the posterior pair is also prominent in P.? dravidicus . Lane (1971) showed that pygidia were the most informative sclerite in cheirurids, and it seems improbable that P.? dravidicus is a cheirurine given its pygidial structure. Eccoptochile has a pygidium with three pairs of obtuse spines (type material of the type species in Horný & Bastl, 1970, pl. 14, fig. 1). The pygidium of Placoparina Whittard, 1940 , is generally similar. However, the relatively obtuse lobes, and their marked fulcrum are more like those on Placoparina ( Whittard, 1958) than Eccoptochile , and dravidicus is tentatively assigned herein to Placoparina . The identity of Reed’s species cannot confidently be resolved without further collections.

Figures

FIGURE 13. (1) Hadromeros? submitis (Reed), Cranidium (original of Reed 1915, pl. 8, fig. 13), GSI 11560, Li-Lu Formation (Katian); Lilu, northern Shan State, Myanmar. (2) Placoparina? dravidicus (Reed), Pygidium (original of Reed 1915, pl. 8, fig. 12), GSI 11559, Lower Naungkangyi Beds; Mâ Shio, northern Shan State, Myanmar. (3) Sphaerocoryphe sp. (Reed), Cranidium (original of Reed 1906, pl. 5, fig. 26), GSI 8340, Naungkangyi Beds, Insang, northern part of Shan State, Myanmar. (4–9) Yanhaoia wynnei (Reed) from the Li-Lu Formation (Katian) and Hwe Mawng Beds (uppermost Katian), northern Shan State, Myanmar. 4. Cranidium (original of Reed 1915, pl. 9, fig. 3), GSI 11569, Mân-ngai. 5. Partial cranidium (original of Reed 1915, pl. 9 fig. 7), GSI 11573, Hwe Mawng. 6. Partial cranidium (original of Reed 1915, pl. 9, fig. 11), GSI 11577, Mong Ha. 7. Pygidium (original of Reed 1915, pl. 9, fig. 12), GSI 11578, Hpakhi. 8. Cranidium and thorax (cast from lectotype, original of Reed 1915, pl. 9, fig. 10), GSI 11576, Hwe Mawng. 9. Pygidium (original of Reed 1915, pl. 9, fig. 5), GSI 11571, Nawng Yu. (10–11) Dalmanitina? dagon (Reed) from the Li-Lu Formation (Katian) and Hwe Mawng Beds (uppermost Katian), northern Shan State, Myanmar. 10. Cranidium (refigured from Reed 1915, pl. 9, fig. 2), GSI 11568-11572, Mân-ngai. 11. Cephalon (original of Reed 1915, pl. 9, fig. 1), GSI 11568, Mân-ngai. (12) Illaenus sp. (Reed), Partial cranidium (refigured from Reed 1917, pl. 8, fig. 3), GSI 11906, Shihtien Formation (Darriwilian), Pupiao, Baoshan Prefecture, western Yunnan, China. Scale bar = 2 mm for 1, 3, 4, 6–9; = 5 mm for 2, 5, 10–12.