Peng et al.—Revision of oryctocephalid genra


Other species.—Duyunaspis paiwuensis Lei and Peng, 2014 (p. 357, figs. 4, 5a), from the Balang Formation, Paiwu, Huayuan, northwestern Hunan.


Diagnosis.—Micropygous genus of the Oryctocarinae with large, broadly subrectangular glabella; glabellar furrows present or absent, connected or separated from axial furrow; palpebral


lobe long, occupying nearly half of glabellar length; palpebral field narrow, less than half of glabellar width. Thorax fulcrate, with nine segments; thoracic axis about as wide as pleural region; fulcrum located about one-third distance from axial furrow. Pygidium broad and short, axis with three rings plus a terminal piece; interpleural furrows poorly defined; lateral and posterior border poorly defined; posteromedial notch on margin commonly present. Dorsal surface smooth or covered with fine granules.


Remarks.—McNamara et al. (2006) and Lei and Peng (2014) discussed Duyunaspis in detail. Two species assigned to this genus are considered properly recognizable: Duyunaspis duyunensis and D. paiwuensis Lei and Peng, 2014 (p. 357, fig. 4). Lei and Peng (2014) provided an expanded concept of the genus, and that concept is followed here. Five species described from the Balang Formation in either northwestern Hunan or eastern Guizhou, South China, have been assigned to Duyunaspis, but, upon review by Lei and Peng (2014, p. 355), were determined to fall within the range of morphologic varia- tion of D. duyunensis, and were therefore regarded as junior synonyms. We concur with that conclusion. The species are: (1) Duyunaspis guzhangensis Zhou (in Zhou et al., 1977, p. 132, pl. 41, fig. 7), based on a single exoskeleton collected from Guanba, Guzhang, northwestern Hunan; (2) Duyunaspis


songtaoensis Qian and Lin (in Zhou et al., 1977, p. 132, pl. 41, fig. 8), based on a single exoskeleton from Xiunao, Songtao, eastern Guizhou; (3) Duyunaspis briaris Qian and Lin (in Yin and Li, 1978, p. 445, pl. 156, fig. 4), based on a single cranidium from Xiunao, Songtao, eastern Guizhou; (4), Duyunaspis obesis Qian and Lin (in Zhang et al., 1980, p. 274, pl. 90, fig. 6), which is an objective junior synonym of D. briaris because both spe- cies are based on the same holotype cranidium; and (5) Duyu- naspis laevigatus Qian and Lin (in Zhang et al., 1980, p. 274, p. 91, figs. 7–9), known from three exoskeletons collected from Xiunao, Songtao, eastern Guizhou. As discussed above, the smallest exoskeleton in Bergeron’s


type series of Arthricocephalus chauveaui (Figs. 1.8, 2.12) is conspecific with D. duyunensis. Duyunaspis was diagnosed by McNamara et al. (2006, p. 7)


as having seven thoracic segments and five pygidial rings. New material illustrated both here and by Lei and Peng (2014), from


955


the Balang Formation at Mozichong and Paiwu, Huayuan, northwestern Hunan, shows that holaspides have nine thoracic segments and three rings in the pygidial axis, indicating that all exoskeletons illustrated by McNamara et al. (2006) represent meraspid degree 7 individuals. Duyunaspis is easily differentiated from both Arthricocephalus


and Oryctocarella by having a proportionately broader glabella, a narrower fixigena, less well defined glabellar furrows, a longer palpebral lobe, and a broader thoracic axis. Each of the three genera can be distinguished by the number of thoracic segments in holaspides. Duyunaspis has nine thoracic segments, Arthricocephalus has eight thoracic segments and Oryctocarella has


11or12thoracicsegments. Both Duyunaspis and


Arthricocephalus have fulcrate thoraxes, but the fulcra in Duyunaspis lie closer to the axial furrow than in Arthricocephalus. Oryctocarella differs frombothDuyunaspis and Arthricocephalus in lacking fulcra. Both Duyunaspis and Oryctocarella are micropygous, whereas Arthricocephalus is isopygous. Species of Duyunaspis and Oryctocarella commonly show a posteromedial notch on the pygidial margin, but this characteristic is unknown in Arthricocephalus.


Duyunaspis duyunensis Zhang and Qian in Zhou et al., 1977 Figures 1.8, 2.12, 10


1977 Duyunaspis duyunensis Zhang and Qian in Zhou et al., p. 132, pl. 41, figs. 5, 6.


1977 Duyunaspis guzhangensis Zhou in Zhou et al., p. 132, pl. 41, fig. 7.


1977 Duyunaspis songtaoensis Qian and Lin in Zhou et al., p. 132, pl. 41, fig. 8.


1978 Duyunaspis laevigatus Qian and Lin in Yin and Li, p. 444, pl. 156, fig. 3.


1978 Duyunaspis songtaoensis; Yin and Li, p. 444, pl. 156, fig. 5.


1978 Duyunaspis duyunensis; Yin and Li, p. 444, pl. 157, fig. 11.


1978 Duyunaspis braris Qian and Lin in Yin and Li, p. 445, pl. 156, fig. 4.


1980 Duyunaspis duyunensis; Zhang et al., p. 273, pl. 91, figs. 5, 6.


1980 Duyunaspis obesis Qian and Lin in Zhang et al., p. 274, pl. 90, fig. 6.


1980 Duyunaspis songtaoensis; Zhang et al., p. 274, pl. 90, fig. 7; pl. 91, fig. 2.


1980 Duyunaspis laevigatus; Zhang et al., p. 274, pl. 91, figs. 7–9.


1982 Duyunaspis songtaoensis; Liu, 1982, p. 299, pl. 212, fig. 18.


1982 Duyunaspis guzhangensis; Liu, p. 299, pl. 212, fig. 14.


Figure 9. Oryctocarella duyunensis (Qian, 1961) from the Balang Formation at Bulin and Mozichong, Huayuan, northwestern Hunan, China; all in dorsal views unless stated otherwise. White arrowhead indicates the posterior margin of thorax; arrowhead with black outline indicates the posterior margin of partially released segment of transitory pygidium; black triangle indicates posteromedial notch; d = doublure: (1) NIGP 164859, exoskeleton, meraspis degree 6, BL-1; (2) NIGP 164860, exoskeleton, meraspis degree 7, BL-1; (3) NIGP 164861, exoskeleton, meraspis degree 7, BL-1; (4) NIGP 164862, exoskeleton, meraspis degree 7, BL-1; (5) NIGP 164863, exoskeleton, meraspis degree 9, MZC-2; (6) NIGP 164864, exoskeleton, meraspis degree 9, BL-1; (7) NIGP 164865, exoskeleton with detached cranidium, meraspis degree 9, BL-1; (8) retrodeformation of specimen in 9 with inferred strain ellipse; (9), NIGP 164866, exoskeleton, meraspis degree 10, BL-1; (10) retrodeformation of specimen in 11 with inferred strain ellipse; (11) NIGP 164867, exoskeleton, meraspis degree 9, BL-1; (12), retrodeformation of specimen in 13 with inferred strain ellipse; (13) NIGP 164868, exoskeleton, meraspis degree 9, BL-1; (14) retrodeformation of specimen in 15 with inferred strain ellipse; (15) NWU-DYXJT 1823, exoskeleton, holaspid, MZC-1; (16) NIGP 164869, metaprotaspis with distinctly divided axis, distinct eye ridge and dot-like palpebral lobe, BL-1; (17, 18) NIGP 164870, external mold of exoskeleton, ventral view, meraspis degree 10 (17), and enlargement of hypostome (18), BL-1. All scale bars represent 1.0mm.


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