Illaenus sp. 2

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 : 346

Illaenus sp. 2

Figs 14.8 , 11

1917 Illaenus aff. schmidti Nieszkowski 1857 ; Reed p. 46–7, pl. 7, figs 12,13.

Material. Incomplete cranidium, Fig. 14.11 ( Reed, 1917, pl. 7, fig. 13), GSI 11902; pygidium, Fig. 14.8 ( Reed, 1917, pl. 7, fig. 12), GSI 11901. Both specimens from Shihtien Formation (Darriwilian) at Banpo Village in Shidian County, Baoshan Prefecture, western Yunnan.

Remarks. This species is represented by an apparently crushed incomplete internal mould of a cranidium, and a pygidium in relief, also lacking the dorsal cuticle. The pygidium has broken to show the upper surface of the doublure, which is wide (sag.) and extends as far as the tip of the acutely triangular, short pygidial axis. A patch of the lower surface of the doublure with terrace ridges is also visible. This structure is typical of Illaenus sensu stricto, but little more can be said about this species.

Figures

FIGURE 11. Encrinurella insangensis (Reed) from the Li-Lu and Kunlein Formations (Katian), northern Shan State, Myanmar. 1a, b. Cranidium (original of Reed 1915, pl. 8, fig. 16), GSI 11562, Hweyawt, original and retrodeforamtion. 2. Cranidium (original of Reed 1915, pl. 8, fig. 15), GSI 11561, Mân-ngai. 3. Cranidium (original of Reed 1915, pl. 8, fig. 18), GSI 11564, Makmongshai. 4. Cranidium (original of Reed 1906, pl. 5, fig. 24), GSI 8338, Kun-lein. 5. Pygidium (original of Reed 1915, pl. 8, fig. 19), GSI 11565, Mân-ngai. 6. Pygidium (original of Reed 1915, pl. 8, fig. 20), GSI 11566, Mân-ngai. 7. Pygidium (original of Reed 1906, pl. 5, fig. 20), GSI 8336, Insang. 8. Thorax (original of Reed 1906, pl. 5, fig. 25), GSI 8339, Ledet. 9. Cranidium and pygidium (lectotype, original of Reed 1906, pl. 5, figs 21&22), GSI 8335, Hweyawt. 10. Cranidium and pygidium (original of Reed 1906, pl. 5, figs 19 and 23), GSI 8334, Hweyawt. Scale bars = 2 mm.

FIGURE 14. (1–7) Parillaenus liluensis (Reed) from the Li-Lu formation (Katian), Lilu, northern Shan State, Myanmar. 1. Cranidium (original of Reed 1915, pl. 7, fig. 10), GSI 11541. 2. Cranidium (original of Reed 1915, pl. 7, fig. 12), GSI 11543. 3. Cranidium (refigured from Reed 1915, pl. 7, fig. 4), GSI 11536. 4. Pygidium and partial thorax (refigured from reed 1915 Pl. 7, fig. 7), GSI 11538. 5. Complete specimen (refigured from Reed 1915, pl. 7, fig. 5), GSI 11537. 6. Complete specimen (original of Reed 1915, pl. 7, fig. 5), GSI 11537. 7. Hypostome (refigured from Reed 1915, pl. 7, fig. 6), GSI 11537. (8, 11) Illaenus sp. 2 (Reed) from the Shihtien Formation (Darriwilian, Banpo Village, Shidian County, Baoshan Prefecture, western Yunnan, China. 8. Pygidium (original of Reed 1917, pl. 7, fig. 12), GSI 11901. 11. Cranidium (original of Reed 1917, pl. 7, fig. 13), GSI 11902. (9, 10) Illaenus sp. 1 (Reed) from the Hwe Mawng Beds (uppermost Katian) and Li-Lu Formation (Katian), northern Shan State, Myanmar. 9. Cranidium (original of Reed 1915, pl. 7, fig. 8), GSI 11539, Hwe Mawng. 10. Cranidium (original of Reed 1915, pl. 7, fig. 9), GSI 11540, Mân-ngai. (12) Illaenus sp. 3 (Reed), Cranidium (original of Reed 1917, pl. 8, fig. 1), GSI 11905, Shihtien Formation (Darriwilian), Pupiao, Baoshan Prefecture, western Yunnan, China. Scale bar = 1 mm for 1, 2, 7; = 5 mm for 3, 8–12; = 2 mm for 4–6.