Hadromeros? submitis ( Reed, 1915 ), 1971

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 : 340-341

Hadromeros? submitis ( Reed, 1915)

Fig. 13.1

1915 Cheirurus submitis Reed , p. 49, pl. 8, figs 13,14.

Material. Lectotype (selected herein): cranidium from Upper Naungkangyi Beds (Katian), Lilu, northern Shan State, Myanmar, Fig. 13.1 ( Reed, 1915, pl. 8, figs 13,14), GSI 11560.

Discussion. We illustrate here a cast taken from the lectotype, original of Reed (1915, pl 8. fig. 14). Only the cephalon is known of this species, which is only generally cheirurine, and invites comparison with those of many other species of similar age. It does, however, have very large, prominent but scattered tubercles on the cheeks and frontal lobe of the glabella. Many somewhat similar later Ordovician Chinese cheirurines have been assigned to the genus Parisoceraurus by Zhou & Zhen (2008) but these do not have such prominent tubercles. One species from the Pagoda Formation of Sichuan attributed (under open nomenclature) to Hadromeros by Zhou et al. (2016, pl. 14, fig. 14) does invite comparison with H.? submitis in showing very coarse, scattered tubercles over the fixed cheeks and forward part of the glabella, and may support a tentative assignment to Hadromeros . However, the Sichuan specimen and the type species of Hadromeros both show relatively long (tr.) glabellar furrows compared with H.? submitis , while the frontal glabellar lobe of the latter is relatively short (sag.) and wide. This structure seems to be unusual in cheirurids, and the distinctive glabellar lobation of the Myanmar species may indicate that it could belong to an undescribed genus, but without a pygidium this cannot be verified.

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.