940
Journal of Paleontology 91(5):933–959
the monospecific Oryctocarella as a junior synonym of Arthricocephalus. Blaker and Peel (1997, p. 109) likewise suppressed Oryctocarella, noting that the holotype exoskeleton of O. sibirica is “comparable in all morphological features to A. chauveaui.” Shergold (1969, p. 40) noted that O. sibirica has segmentation identical with Arthricocephalus chauveaui,and that Suvorova (1964) had considered the two genera as possible syno- nyms. However, Peng et al. (2015) considered that Oryctocarella should be revived as a valid genus because it is significantly distinguishable in exoskeletal characters from Arthricocephalus. Unfortunately, the type material of Tomashpolskaya and
Karpinski (1961) is lost (Korovnikov and Novozhilova, 2017), and the original figures of O. sibirica are poor, making it hard to determine its diagnostic features, especially the exact number of thoracic segments. From the original illustration of the holotype (Tomashpolskaya and Karpinski, 1961, pl. 1, fig. 2), it appears that O. sibirica has at least nine thoracic segments. Recently collected topotypic material of O. sibirica from its type locality in the Kuznetsk Alatau, Altay-Sayan Foldbelt (see Fig. 6) reveals that the species has nine or possibly 10 thoracic seg- ments. In addition, topotypes show that O. sibirica shares a number of important characters with O. duyunensis, allowing clear distinction from A. chauveaui (see Fig. 3). Distinguishing characters include a cylindrical glabella, pit-like glabellar fur- rows that are isolated from the axial furrows, a non-fulcrate thorax, and a relatively short pygidium with clearly defined interpleural furrows. A pygidial border and border furrow are not defined. These characters clearly differentiate Oryctocarella from Arthricocephalus so that, following Peng et al. (2015) and Korovnikov and Novozhilova (2017), the genus must be regarded as valid and discrete. A large number of specimens from China previously
assigned to Arthricocephalus are referable to Oryctocarella. They include specimens illustrated as Arthricocephalus duyunensis Qian, 1961,A. granulus Qian and Lin in Zhou et al., 1977,A. jiangkouensis Yin in Yin and Li, 1978, A. tenuis Zhang and Zhou, 1985, and A. cf. A. granulus sensu Zhang and Zhou, 1985. Some of these described species are regarded here as synonymous with Oryctocarella duyunensis (Qian, 1961).
Materials and methods
Figured specimens were collected from the Cambrian Balang Formation in various localities of South China and from the lower part of the traditional Middle Cambrian in a single locality of Siberia, Russia. The localities are indicated by these acro- nyms: BL = Bulin, Huayuan, northwestern Hunan, China; DZ = Nangao, Danzhai, eastern Guizhou, China;DM = Dolgii Mys (Long Cape) Mountain, Khakassia, Batenevsky Ridge, Kuznetsk Alatau, Altay-Sayan Foldbelt, Russia; GY = Palang (previously misspelled as Balang), Duyun, southeastern Guizhou, China; HN-GZ = Border area between Hunan and Guizhou provinces, China (exact collecting locality unknown); KH = Panxin and Feilongshan, Songtao, eastern Guizhou, China; LYX = Luoyixi, Guzhuang, northwestern Hunan, China; MZC = Mozichong, Huayuan, northwestern Hunan, China; TJBL = Balang, Taijiang, eastern Guizhou, China; TR = Tongren, eastern Guizhou, China; WW = Wawu, Tongren, Guizhou, China (village that has administrative
jurisdiction over the type locality of A. chauveaui); XHZA = Paiwu (Zila A), Huayuan, northwestern Hunan, China; XHZB = Paiwu (Zila B), Huayuan, northwestern Hunan, China; XS = Xiaosai, Yuqing, eastern Guizhou, China. Specimens inBergeron’s (1899) type series of Arthricocephalus
chauveaui were coated with magnesium oxide and then photo- graphed with an Olympus OM4 film camera. Topotypes of Oryctocarella sibirica were photographed with a digital camera. All other specimens were coated with black ink and followed by magnesium oxide, then photographed under a Zeiss stereo- microscope (Model Axio Zoom V16) having a digital head (AxioCam MrM) and a circle light around the lens providing uniform lighting. Measurements were made from images of sclerites using the ruler tool in Adobe Photoshop CS6. Scale bars were either photographed along with the images of speci- mens by film photography or produced automatically by digital photography.
Repositories and institutional abbreviations.—Illustrated and referred specimens are deposited in the following institutions: CSGM, Central Siberian Geological Museum, Novosibirsk, Russia; E.M., Geological Department, Claude Bernard University, Lyon, France; Gt, Guizhou Institute of Regional Geological Survey, Guiyang, Guizhou, China; NIGP, Nanjing Institute of Geology and Palaeontology, Nanjing, China; NWU, Geological Department, Northwest University, Xi’an, China.
Spellings of author names.—English spellings of the names of some Chinese authors have changed through time. The Pinyin (Chinese Phonetic Alphabet), introduced in 1958, was accepted in 1982 as the International Standard for the Spelling of Chinese Characters (ISO7098), and it is Pinyin spellings that are used here. Names of Chinese authors affected by the change to Pinyin spellings include Guo (changed from Kuo), Li (from Lee), Qian (from Chien), Xiang (from Hsiang), Zhang (from Chang), and Zhu (from Chu). Transliterated names of Russian authors follow commonly
accepted spellings.
Systematic paleontology Terminology mostly follows that of Whittington and Kelly (1997). In the following descriptions, “long” and “short” are used with reference to longitudinal (sagittal, sag., and exsagittal, exsag.) dimensions, and “broad” (or “wide”)and “narrow” are used with reference to transverse (tr.) dimensions (Whittington, 1997, p. O2).
Order Corynexochida Kobayashi, 1935 Family Oryctocephalidae Beecher, 1897 Subfamily Oryctocarinae Hupé, 1953 Genus Arthricocephalus Bergeron, 1899
1899 Arthricocephalus Bergeron, p. 514. 1974 Arthricocephalus (Arthricocephalites) Qian and Lin in Lu et al., p. 94.
1988 Arthricocephalus Bergeron; Lane et al. (part), p. 555. 1997 Haliplanktos Blaker and Peel, p. 112. 2002 Arthricocephalites Qian and Lin in Yuan et al., p. 122.
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