Peng et al.—Revision of oryctocephalid genra


Type species.—Oryctocara sibirica Tomashpolskaya in Khalfin, 1960 (p. 199, pl. 23, fig. 5), from the lower part of the traditional middle Cambrian, Batenevsky Ridge, Kuznetsk Alatau, Altay-Sayan Foldbelt, Russia; by original designation.


pl. 1, fig. 19, pl. 2, figs. 5, 7–10; non pl. 1, fig. 20, pl. 2, fig. 6 [ = Arthricocephalus chauveaui Bergeron, 1899]), fromthe Balang Formation, Palang, Duyun, eastern Guizhou, China; Arthricocephalus (Arthricocephalites) balangensis Qian and Lin in Yin and Li, 1978 (p. 442, pl. 157, fig. 10), from the Balang Formation, Palang, Duyun, eastern Guizhou, China.


Diagnosis.—Micropygous genus of Oryctocarinae with gently curved or transverse anterior margin, surface sculpture granu- lated or smooth. Glabella subrectangular to cylindrical, defined laterally by nearly straight axial furrows; S1–S4 pit-like or narrow incision, with S1–S3 distant from axial furrow, con- nected by weak or faint transverse furrows. Palpebral lobe notably oblique, located near or anterior to glabellar mid-length, palpebral area subequal in width with glabella. Facial suture proparian. Thorax non-fulcrate, consisting of 9–11, or rarely 12, segments; axis about half as wide as pleural region. Pygidium


Other species.—Arthricocephalus duyunensis Qian, 1961 (p. 97,


947


much shorter than cranidium, axis about half of pygidial length, with three rings and a tiny terminal piece; interpleural furrows well defined; borders absent, margin may have a pos- teromedial notch.


Remarks.—Oryctocarella is here regarded as a valid genus. Differences between the type species of Oryctocarella and Arthricocephalus are discussed at length above, and differences between A. chauveaui and O. duyunensis are illustrated in Figure 3.Oryctocarella is distinguished fromArthricocephalus in having a pygidium that is much shorter than the cephalon; a cylindrical glabella; pit-like glabellar furrows, most of which do not reach to the axial furrows; a larger number of thoracic segments; and well-defined interpleural furrows in the pygidium. In addition, the thoracic segments lack fulcra, and a pygidial border is not clearly developed in Oryctocarella.


Oryctocarella sibirica (Tomashpolskaya in Khalfin, 1960) Figure 6


1960 Oryctocara sibirica Tomashpolskaya in Khalfin, p. 199, pl. Cm-23, fig. 5.


1961 Oryctocarella sibirica; Tomashpolskaya and Karpinski, p. 156, pl. 1, figs. 1–6.


Figure 6. Oryctocarella sibirica (Tomashpolskaya in Khalfin, 1960), topotypes from the lower part of the Karasuk Formation, Region of Dolgii Mys range (DM), Kuznetsk Alatau, Altay-Sayan Foldbelt, Russia; all in dorsal view. White arrowhead indicates the posterior margin of thorax; arrowhead with black outline indicates the posterior margin of partially released segment of transitory pygidium; ltr = last thoracic axial ring; 9 = ninth thoracic segment: (1) neotype CSGM2075/2, proposed here, incomplete cranidium, original specimen of Korovnikov and Novozhilova (2017, pl. 5, fig. 2); (2) CSGM2075/17, incomplete cranidium; (3) CSGM2075/16, latex cast from external mold of incomplete cranidium; (4) CSGM 2075/5, incomplete exoskeleton, meraspis degree 8, original specimen of Korovnikov and Novozhilova (2017, pl. 5, fig. 5); (5) CSGM2075/6, thoracopygon, holaspid?, with nine thoracic segments, original specimen of Korovnikov and Novozhilova (2017, pl. 5, fig. 6); (6) enlarged posterior part of CSGM2075/6 in 5, showing the broken last thoracic axial ring (ltr) on the ninth segment. All scale bars represent 1.0mm.


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