Dalmanitina ? dagon (Reed, 1915) Figs 13.10, 11 1915 Phacops (Pterygometopus) dagon; Reed, pl. 9, figs 1–6, non fig. 3. Material. Lectotype (selected herein): cephalic shield, original of Reed (1915) pl. 9, fig 1, GSI 11568. Pygidium, original of Reed (1915) pl. 9, fig. 5, GSI 11571. Upper Naungkangi Beds, Mangai. All specimens from Upper Naungkangyi Beds (Katian) at Man Ngai, northern Shan State. Discussion. As considered above, Reed (1915) described a variety of what he termed Phacops (Pterygometopus) dagon as var. wynnei, which is regarded herein as a different taxon. The material of the nominate species is limited, and we have not been able to cast some of the original specimens, as they are fragile. The robust largest cranidium is selected as lectotype. A smaller cephalon illustrated by Reed (1915, pl. 9 fig. 2; Fig. 13.10) shows a well-defined anterior border, which was likely also present on the lectotype, though obviously broken medially in that specimen. Such a border is atypical of Dalmanitina, and may possibly suggest such genera as Mucronaspis, but without knowledge of the rest of the exoskeleton we prefer a provisional allocation to the older established genus. This border is extremely narrow on wynnei. The glabella of dagon is comparatively transverse anteriorly, and the bifurcation of the S1 is not so marked. Another small? cephalon illustrated by Reed (1915, pl. 9, fig. 3) is more like wynnei and is excluded from dagon here. The generic assignment of D. ? dagon is equivocal, and the eyes are longer (exag.) than is typical for the dalmanitines according to Holloway (1981), a subfamily hard to delimit (Hammann & Leone, 2007). The species is placed provisionally in Dalmanitina pending a more comprehensive revision of Late Ordovician species.
Published as part of 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, pp. 301-356 in Zootaxa 5162 (4) on pages 342-343, DOI: 10.11646/zootaxa.5162.4.1, http://zenodo.org/record/6810290
{"references":["Reed, F. R. C. (1915) Supplementary Memoir on new Ordovician and Silurian fossils from the Northern Shan States. Palaeontologia Indica, New Series 6, 1 - 98.","Hammann, W. & Leone, F (2007) Trilobites from the post-Sardic (Upper Ordovician) sequence of southern Sardinia. Part 2. Beringeria, 38, 1 - 138."]}