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(1)Geosciences Journal Vol. 9, No. 2, p. 107 − 115, June 2005. Two Cambrian agnostoid trilobites, Agnostotes orientalis (Kobayashi, 1935) and Lotagnostus americanus (Billings, 1860): Key species for defining global stages of the Cambrian System Shanchi Peng* Loren E. Babcock. Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing 210008, China Department of Geological Sciences, 125 South Oval Mall, The Ohio State University, Columbus, Ohio 43210, U.S.A.. ABSTRACT: The systematics, stratigraphic distribution and geographic distribution of two widely distributed agnostoid species from the Furongian Series of the Cambrian are reviewed. The species Agnostotes orientalis (Kobayashi, 1935) and Lotagnostus americanus (Billings, 1860) have been described from around the world under a variety of species and subspecies names, and have been assigned to a variety of genera. Nomenclatural problems have hindered to some extent a full understanding of the value of these two forms for intercontinental correlation. Both species have relatively narrow stratigraphic ranges and intercontinental distributions in open-shelf lithofacies. These conditions make these species excellent candidates for defining the bases of stage boundaries within the Furongian Series.. lent candidates for defining the bases of the middle and upper stage, respectively within the Furongian Series (Babcock et al., in review). If the FADs of these two species were ultimately selected to define the bases of these stages, the Furongian Series would be divided into three subequal parts.. Key words: Cambrian, Furongian, trilobite, agnostoid. BGS CPC. 1. INTRODUCTION Recent discussion within the International Subcommission on Cambrian Stratigraphy has centered about the best biologic tools for defining subdivisions of stages within the Cambrian System. Two easily recognizable, widely distributed agnostoid trilobites, Agnostotes orientalis (Kobayashi, 1935) and Lotagnostus americanus (Billings, 1860), have emerged as candidates for defining the bases of two stages within the Furongian Series (the uppermost series of the Cambrian System; Babcock et al., 2005). Specimens evidently referable to these species have been described under a number of names on separate paleocontinents, and to facilitate understanding of the paleogeographic distributions of the species, it is necessary to clarify the concepts of both species and their synonyms. Both A. orientalis and L. americanus have relatively narrow stratigraphic ranges and wide (intercontinental) distributions in open-shelf lithofacies. The first appearance datum (FAD) of A. orientalis occurs about one-third of the way from the base of the Furongian, and the FAD of L. americanus occurs about two-thirds of the way from the base of the Furongian. Therefore these species can serve as excel*Corresponding author: [email protected]. 2. SYSTEMATIC PALEONTOLOGY Illustrated trilobite specimens are deposited in the collections of the institutions listed below. British Geological Survey, Nottingham, UK Commonwealth Palaeontological Collection, Bureau of Mineral Resources, Canberra, Australia GMAN Geological Museum, Geological Institute, Kazakhstan Academy of Sciences, Almaty (Alma Ata), Kazakhstan GSC Geological Survey of Canada, Ottawa, Canada LU Laval University, Montreal, Canada MCNAM Museo de Ciencias Naturales y Antropológicas Juan Cornelio Moyano, Mendoza, Argentina NIGP Nanjing Institute of Geology and Palaeontology, the Chinese Academy of Sciences, Nanjing, China. ROM Royal Ontario Museum, Toronto, Canada SGU Swedish Geological Survey, Uppsala, Sweden SNIIGGiMS Siberian Research Institute of Geology, Geophysics and Mineral Resources, Novosibirsk, Russia SNUP Seoul National University, Seoul, South Korea XTR Xinjiang Regional Surveying Team, Bureau of Geology and Mineral Resources, Urumuqi, China Class Trilobita Walch, 1771 Order Agnostida Salter, 1864 Family Pseudagnostidae Whitehouse, 1936 Subfamily Pseudagnostidinae Whitehouse, 1936 Genus Agnostotes Öpik, 1963.

(2) 108. Shanchi Peng and Loren E. Babcock. Agnostotes Öpik, 1963, p. 43; Zhu et al., 1979, p. 83; Xiang and Zhang, 1985, p. 88; Pratt, 1992, p. 39; Shergold and Laurie, 1997, p. 366; Choi et al., 2004, p. 173. Pseudoglyptagnostus Lu, 1964, p. 32; Lu et al., 1965, p. 33; 1974, p. 83. Glyptagnostotes Lazarenko, 1966, p. 42; Ergaliev, 1980, p. 101. Agnostotes (Pseudoglyptagnostus) Lu. Lu and Lin, 1989, p. 89; Shergold et al., 1990, p. 50; Shergold and Laurie, 1997, p. 368; Peng, 1992, p. 25; Zhang, 2000, p. 96. Agnostotes (Agnostotes) Öpik. Shergold et al., 1990, p. 50; Shergold and Laurie, 1997, p. 367; Peng, 1992, p. 25. Type species: Agnostotes inconstans Öpik, 1963; by original designation. Remarks: We follow Pratt (1992, p. 39) and Peng (1992, p. 25) in recognizing that Pseudoglyptagnostus and Glyptagnostotes are junior synonyms of Agnostotes. Pratt (1992) included six species in Agnostotes: A. inconstans (Öpik, 1963), A. clavata (Lu, 1964), A. elegans (Lazarenko, 1966), A. sulcatus (Lin and Zhang in Zhu et al., 1979), A. houchengensis (Zhang, 1981), A. tianshanicus (Zhang, 1981), and A. mirus (Xiang and Zhang, 1985). To this list, Peng (1992) added one additional species, A. latilimbatus. Furthermore, Öpik (1963, p. 44) identified a fragmentary agnostoid pygdium as Agnostus (Ptychagnostus?) orientalis (Kobayashi, 1935). Neoagnostus kentauensis (Ergaliev, 1983, p. 43, pl. 1, fig. 24, pl. 3, figs. 1–4; Apollonov et al., 1984, pl. 15, figs. 1–4) apparently belongs to Agnostotes, and is regarded here as a junior synonym of A. sulcatus. Specimens assigned to A. tianshanicus (Zhang, 1981) by Xiang and Zhang (1985, p. 8, figs. 3–5, 8–10) are conspecific with A. sulcatus. The occurrences of A. kentauensis, A. houchengensis, A. tianshanicus, and A. mirus recorded in Bolshoi Karatau and the Northern Tianshan (Ergaliev, 1983; Xiang and Zhang, 1985) indicate that they are chronostratigraphically younger species of Agnostotes. Agnostotes orientalis (Kobayashi, 1935) Figure 1.1–1.20 Agnostus (Ptychagnostus?) orientalis Kobayashi, 1935, p. 105, pl. 14, figs. 11, 12. Pseudoglyptagnostus clavatus Lu, 1964, p. 32, pl. 4, fig. 7; Lu et al.,1965, p. 33, pl. 2, fig. 20; Lu et al., 1974, p. 83, pl. 1, fig. 9; Lu and Lin, 1983, pl. 2, fig. 6; Qiu et al., 1983, p. 35, pl. 12, figs. 6, 7. Glyptagnostotes elegans Lazarenko, 1966, p. 43, pl. 2, figs. 1-12; Ergaliev, 1980, p. 101, pl. 12, fig. 8. Agnostotes orientalis (Kobayashi, 1935). Öpik, 1963, p. 44; Choi et al., 2004, p. 173, fig. 10.1-10.7; Choi, 2004, p. 51, fig. 29.1, 29.2. Agnostotes (Pseudoglyptagnostus) clavatus Lu. Lu and Lin, 1989, p. 89, 213, pl. 6, figs. 1-7; Peng, 1992, p. 25, fig.. 10H-10S; Pegel, 2001, figs. 14.11, 12.12. Agnostotes clavata Öpik. Peng, 1990, pl. 1, figs. 19, 20; Pratt, 1992, p. 39, pl. 4, figs. 29-34; Chatterton and Ludvigsen, 1998, p. 13, fig. 8.10-8.14. Agnostotes (Pseudoglyptagnostus) orientalis (Kobayashi). Zhang, 2000, p. 96, text-fig. 1a, 1b. Holotype: An external mold of a pygidium (Kobayashi, 1935, pl. 14, figs. 11, 12) from the Machari Formation, Yeongwol area, Korea, by monotypy. Remarks: Kobayashi (1935, p. 105, figs. 11, 12) described and illustrated Agnostus (Ptychagnostus?) orientalis on the basis of a single external mold of a fragmentary pygidium from the Machari Formation of South Korea. The specimen (reillustrated by Zhang, 2000, text-fig. 1A, 1B; Fig. 1.1, 1.2) is complete enough to show the distinctive posteroaxis, which is divided longitudinally into three parts; a narrow border; and distinctive scrobiculae. Well-preserved material, also from the Machari Formation, was recently described and illustrated by Choi et al. (2004) and Choi (2004) as Agnostotes orientalis (Kobayashi). This material appears to be conspecific with Kobayashi’s (1935) specimen, and permits comparison with other specimens of Agnostotes from sites in other areas of the world. The material illustrated by Choi et al. (2004) and Choi (2004) occurs in close association with the polymerid trilobite Irvingella, and the holotype shows a specimen of Irvingella preserved on the same slab (Zhang, 2000, text-fig. 1D). In addition to the features noted from the fragmentary holotype, the material illustrated by Choi et al. (2004) and Choi (2004) shows that the species possesses an anteriorly notched anterior lobe of the glabella; a narrow anteroaxis and a greatly expanded posteroaxis on the pygidium; and a pair of tiny marginal spines at the posterolateral corners of the pygidium. No notch (or frontal sulcus) is known in any other species of Agnostotes. The combination of these characters is sufficient to show that specimens previously referred to Pseudoglyptagnostus (later Agnostotes) clavatus Lu (1964) and Glyptagnostotus (later Agnostotes) elegans Lazarenko, 1966 are conspecific with A. orientalis. Pratt (1992) noted that variation exists in the degree of effacement of scrobicules among specimens that he referred to as A. clavatus from the Mackenzie Mountains of Canada. Similar variation is observable among specimens illustrated from Siberia (Lazarenko, 1966; Pegel, 2000). Choi et al. (2004) recently suppressed A. elengans as a junior synomym of A. orientalis. Ontogenetic material from Zhejiang (Lu and Lin, 1989), Hunan (Peng, 1992), and Siberia (Lazarenko, 1966) shows that the anterior axis of the pygidium becomes proportionately wider (tr.) with growth, and that scrobicules on both the cephalon and pygidium become more numerous and distinct. Geographic and stratigraphic distribution: A. orientalis.

(3) Two Cambrian agnostoid trilobites, Agnostotes orientalis (Kobayashi, 1935) and Lotagnostus americanus (Billings, 1860). 109. Fig. 1. (1–20) Agnostotes orientalis (Kobayashi, 1935). (1, 2) Fragmentary external mold (1) and latex cast (2) from the mold, holotype, ×9 (1), ×8 (2), UMUT-PAO957, original of Kobayashi, 1935, pl. 14, figs. 11, 12, Machari Formation, Yeongwol area, Korea. (3, 4) Cephalon (3) and pygidium (4), original of Choi et al., 2004, fig. 10.2, 10.5 (refigured by Choi, 2004, fig. 29.1, 29.2), SNUP 671, ×5 (3), SNUP 674, ×5 (4); from the Agnostotes orientalis Zone, Machari Formation, near Gonggiri, Yeongwol, Korea. (5) Exoskeleton, latex cast, described originally as the holotype of Pseudoglyptagnostus clavatus (Lu, 1964, pl. 4, fig. 7), NIGP 23719, ×6.5, from the Huayansi Formation, Xiyanshan, Changshan, western Zhejiang, China. (6–9) Cephala (6, 7) and pygidia (8, 9), originally described as Agnostotes (Pseudoglyptagnostus) clavatus by Peng (1992), NIGP 94973, ×15 (6), NIGP 94974, ×15 (7), NIGP 94980, ×10 (8), NIGP 94979, ×12 (9); from the Agnostotes clavata-Irvigella angustilimbata Zone of the Huaqiao Formation, Shenjiawan, Cili, northwestern Hunan, China. (10, 17, 19) Type material of Glyptagnostotes elegans Lazarenko (1966), museum number uncertain; holotype exoskeleton, ×4.5 (10), paratype pygidium, ×7 (17), paratype exoskeleton, ×7 (19); all from the Irvingella-Cedarellus felix Zone, Furongian (Upper Cambrian of Siberian usage), northeastern Siberian Platform. (11) Pygidium referred to Agnostotes (Pseudoglyptagnostus) clavatus by Lu and Lin (1989), NIGP 66241, ×16, from the Pseudaglyptagnostus clavatus-Siniproceratopyge kiangshanensis Zone of the Huayansi Formation, Tianmashan, Changshan, western Zhejiang, China. (12–14, 16) Specimens referred originally to Agnostotes clavata by Pratt (1992), cephala (12, 13) and pygidia (14, 16), ROM 46831, ×11 (12), ROM 46833, ×11 (13), ROM 46834a, ×13.5 (14), ROM 46834b ×16 (16); from the Proceratopyge rectispinata fauna of the Rabbitkettle Formation, Mackenzie Mountains, western Canada. (15, 18) Specimens referred to Agnostotes (Pseudoglyptagnostus) clavatus by Pegel (2000), cephalon (15), pygidium (18); SNIIGGiMS 373/ 30, ×7 (15), SNIIGGiMS 373/31, ×14 (18); from the Ogon’or Formation (Furongian; Sakian by Siberian standards), Khos-Nelege River area, Siberia. (20) Pygidium referred to Glyptagnostotes elegans by Ergaliev (1980), GMAN 1950/194a, ×6, from the Pseudagnostus curtare Zone, Malyi Karatau, Kazakhstan. (21, 22) Agnostotes inconstans Öpik, 1963 from the Irvigella tropica Zone, Burke River area, Australia, (21) cephalon, CPC 4274, ×7, (22) pygidium, holotype, CPC 4272, ×6..

(4) 110. Shanchi Peng and Loren E. Babcock. has a narrow stratigraphic range and usually co-occurs with Irvingella in outer-shelf lithofacies. At present, specimens referred to A. orientalis are known from South Korea, Siberia, Kazakhstan, Canada (Mackenzie Mountains, British Columbia), and China (Hunan, Zhejiang). Family Agnostidae M’Coy, 1849 Subfamily Agnostinae M’Coy, 1849 Genus Lotagnostus Whitehouse, 1936 Type species: Agnostus trisectus Salter, 1864 [=L. americanus (Billings, 1860)]; by original designation. Lotagnostus Whitehouse, 1936, p. 101; Troedsson, 1937, p. 25; Palmer, 1955, p. 92; Lu, 1957, p. 260; Lu, 1963, p. 32; Lu, 1964, p. 33; Lu et al., 1965, p. 35; Zhou et al., 1977, p. 112; Lisogor, 1977, p. 210; Yin and Li, 1978, p. 386; Lu and Lin, 1980, p. 123; Zhang, 1981, p. 140; Liu, 1982, p. 291; Qiu et al., 1983, p. 35; Ergaliev, 1983, p. 39; Xiang and Zhang, 1985, p. 89; Lu and Lin, 1989, p. 90; Ludvigsen et al., 1989, p. 11; Shergold et al., 1990, p. 34; Peng, 1992, p. 15; Shergold and Laurie, 1997, p. 341; Ahlberg and Ahlgren, 1996, p. 133. Eolotagnostus Zhou in Zhou et al., 1982, p. 217. Lotagnostus (Lotagnostus) Whitehouse. Lu and Lin, 1984, p. 62; Shergold et al., 1990, p. 34; Shergold and Laurie, 1997, p. 34; Bao and Jago, 2000, p. 890. Lotagnostus (Eolotagnostus) Shergold et al., 1990, p. 34; Peng, 1992, p. 16; Shergold and Laurie, 1997, p. 341. Lotagnostus (Distagnostus) Shergold, 1972, p. 17; Shergold et al., 1990, p. 34; Peng, 1992, p. 15; Shergold and Laurie, 1997, p. 342. Remarks: Ludvigsen et al. (1989) discussed at length the concept and species content of Lotagnostus. Shergold and Laurie (1997) further discussed Lotagnostus and assigned it to the subgenera L. (Lotagnostus), L. (Eolotagnostus), and L. (Distagnostus). The latter two subgenera embrace progressively effaced species of Lotagnostus. Lotagnostus americanus (Billings, 1860) Figure 2 Agnostus americanus Billings, 1860, p. 302, fig. 1a, b; Billings, 1863, p. 233, fig. 250a, b; Billings, 1865, p. 395, fig. 372a, b; Clark, 1924, p. 18, pl. 3, fig. 6; Rasetti, 1944, p. 233, pl. 36, figs. 1-2. Agnostus trisectus Salter, 1864, p.10, pl. 1, fig. 11; Belt, 1868, p. 11; Linnarsson, 1880, p. 27 (157), pl. 2 (6), fig. 16; Tullberg, 1880, p. 24, pl. 1, fig. 13a, b; Matthew, 1894, p. 110; Lake, 1906, p. 10, pl. 1, figs. 15, 16; Westergård, 1922, p. 117, 193, pl. 1, figs. 11, 12. Agnostus trisectus var. A. oruatus Salter, 1864, in part, p. 4, pl. 1, figs. 4, 5 (only).. Agnostus trisectus mut. ponepunctus Matthew, 1903, p. 220, pl. 17, fig. 8a-c. Agnostus innocens Clark, 1924, p. 17, pl. 3, fig. 3a (pygidium only). Lotagnostus asiaticus Troedsson, 1937, p. 25, pl. 1, figs. 10-16; Lu, 1957, p. 260, pl. 138, figs. 2, 3; Lu, 1963, p. 32, pl. 5, figs. 3, 4; Lu et al., 1965, p. 35, pl. 3, figs. 4, 5; Lisogor, 1977, p. 210, pl. 30, figs. 3-21; Lu and Lin, 1980, p. 123, pl. 1, figs. 6, 7; Ergaliev, 1983, p. 39, pl. 1, figs. 6, 7, 9, pl. 5, fig. 5; Lu and Lin, 1989, p. 92, pl. 6, fig. 13, pl. 7, figs. 1-3. Lotagnostus xinjiangensis Zhang, 1981, p. 140, pl. 55, fig. 9. Lotagnostus punctatus Lu, 1964, p. 33, pl. 5, fig. 5; Lu et al., 1965, p. 36, pl. 3, fig. 8; Lu et al., 1974, p. 77, pl. 1, fig. 1; Zhou et al., 1977, p. 112, pl. 36, figs. 29, 30; Lu and Lin, 1980, p. 123, pl. 1, fig. 5; Liu, 1982, p. 291, pl. 207, fig. 2, pl. 208, fig. 7, pl. 209, fig. 5; Ergaliev, 1983, p. 39, pl. 1, figs. 1-5; Lu and Lin, 1983, p. 9, pl. 1, figs. 3, 4; Peng, 1983, p. 50, pl. 1, fig. 1; Peng, 1984, p.315, pl. 1, figs. 1, 2; Lu and Lin, 1989, p. 91, pl. 6, figs. 8-12. Lotagnostus (Lotagnostus) punctatus Lu. Lu and Lin, 1984, p. 62, pl. 3, figs. 8-11; Peng, 1992, p. 15, fig. 6A-6G, 6L. Lotagnostus punctatus punctatus Lu. Xiang and Zhang, 1985, p. 90, pl. 9, figs. 13-15. Lotagnostus punctatus xinjiangensis Zhang. Xiang and Zhang, 1985, p. 90, pl. 10, figs. 3-11. Lotagnostus trisectus (Salter). Hutchinson, 1962, p. 35, 53; Taylor and Cook, 1976, p. 208, text-fig. 29F; Allen et al., 1981, p. 314, pl. 17, figs. 1, 2; Morris, 1988, p. 133; Ahlberg and Ahlgren, 1996, p. 133, fig. 4A, B; Pegel, 2000, p. 1018, fig. 15.6, 15.10; Bao and Jago, 2000, p. 890, pl. 1, figs. 12-15. Goniagnostus verrucosus Rusconi, 1951, p. 27, fig. 5. Lotagnostus obscurus Palmer, 1955, p. 92, pl. 19, figs. 5-7, 10. Lotagnostus americanus (Billings). Ludvigsen et al., 1989, p. 12, pl. 1, figs. 15-17. Lotagnostus (Lotagnostus) punctatus Lu. Peng, 1992, p. 15, fig. 6A-G, L. Lotagnostus (Lotagnostus) trisectus (Salter). Shergold et al., 1990, p. 34, fig. 9.7a, b; Shergold et al., 1995, p. 246, pl. 1, fig. 12; Shergold and Laurie, 1997, p 341, fig. 218.1ac; Tortello and Bordonaro, 1997, fig. 3.6; Bao and Jago, 2000, p. 890, pl. 1, figs. 12-15. Remarks: Billings’s (1860) holotype of Agnostus americanus is an exfoliated pygidium from the Lévis Formation of Quebec. The paratype of the species is a cephalon. Rasetti (1944, pl. 36, fig. 1) referred a scrobiculate cephalon from the Lévis Formation of Quebec to the same species. Later, Ludvigsen et al. (1989) refigured the holotype and the paratype, and further illustrated another scrobiculate cephalon from a boulder of the Shallow Bay Formation.

(5) Two Cambrian agnostoid trilobites, Agnostotes orientalis (Kobayashi, 1935) and Lotagnostus americanus (Billings, 1860). 111.

(6) 112. Shanchi Peng and Loren E. Babcock. Fig. 2. Lotagnostus americanus (Billings, 1860). (1) Cephalon, GSC69584, ×5, original of Ludvigsen et al. (1989, pl. 1, fig. 17), Shallow Bay Formation, western Newfoundland. (2, 4) Pygidium, holotype (2), and cephalon, paratype (4), original of Billings (1860, figs. 1a, b), GSC 859, 859c, ×5.5 (2), ×5.5 (4), from the Lévis Formation, Quebec, Canada. (3) Cephalon, ×5, Laval University, 1101, from the Lévis Formation, Quebec, Canada, original of Rasetti (1944, pl. 1, fig. 1). (5) Pygidium, wax impression, BGS 8768, ×6, described originally as the holotype of Lotagnostus trisectus (Salter, 1984, pl. 1, fig. 1), from the Merioneth Series, Peltura scarabaeoides Zone, Dolgellau, northern Wales, UK. (6, 7) Cephalon (6) and pygidium (7), described originally as Lotagnostus trisectus by Westergård (1922, pl. 1, figs. 11 and 12), SGU 127, ×5.2 (6), SGU 128, ×5.2 (7); from the Peltura minor Zone, Andrarum and Skåne, Sweden. (8, 9) Cephalon (8) and pygidium (9), SNIIGGiMS 373/37, ×6 (8), SNIIGGiMS 373/38, ×5 (9); from the Ogon’or Formation, Furongian (Aksayan of Siberian terminology), Khos-Nelege River area, Siberia, Russia; originally described as Lotagnostus trisectus by Pegel (2000, fig. 15.6, 15.10). (10) Cephalon, MCNAM 9973, ×7, described originally as the holotype of Goniagnostus verrucosus by Rusconi (1951, fig. 5), from the Furongian (Upper Cambrian of Cordilleran terrane usage), Cerro Pelado, Argentina. (11, 12) Cephalon (11) and exoskeleton (12), NIGP unnumbered, ×4.5, described as the holotype (11) and paratype (12) of Lotagnostus asiaticus by Troedsson (1937, pl. 1, figs. 10 and 14), from the Furongian (Upper Cambrian of historical usage), Kuruktagh, Xinjiang, China. (13) Exoskeleton, NIGP 23711, ×5.5, described as the holotype of Lotagnostus punctatus by Lu (1964, pl. 5, fig. 5), from the Lotagnostus punctatus Zone, Siyanshan Formation, Xiyanshan, Changshan, western Zhejiang, China. (14, 21) Exoskeleton (14) and cephalon (21); NIGP 83022, ×6, NIGP 84907, ×4.5; referred to Lotagnostus asiaticus by Peng (1984, pl. 1, fig. 1; 1992, fig. 6a), from the Lotagnostus punctatus – Hedinaspis regalis Zone, Shenjiawan Formation, northwestern Hunan, China. (15) Exoskeleton, ×3.6, NIGP 62208, described as the holotype of Lotagnostus ningguoensis by Qian (in Qiu et al., 1983, pl. 12, fig. 17), from the Furongian (Upper Cambrian of historical usage), Ninguo, Anhui, China. (16, 17, 18) Pygidia (16, 17), and cephalon (18); ×6.5 (16), ×6 (17), ×6.5 (18), referred to Lotagnostus punctatus by Ergaliev (1983, pl. 1, figs. 4, 3, and 2), GMAN 654/ 4 (16), 654/3 (17), 654/2 (18): from the Agnostus scrobicularis Zone, Furongian (Aksayan Stage of Kazakhstanian usage), Bolishoi Karatau, Kazakhstan. (19) Pygidium, ×6.5, referred to Lotagnostus asiaticus by Ergaliev (1983, pl. 1, fig. 6), GMAN 654/6, from the Agnostus scrobicularis Zone, Furongian (Aksayan Stage of Kazakhstanian usage), Bolishoi Karatau, Kazakhstan (from the same collection as 16–18). (20, 22, 23) Cephalon (20) and pygidia (22, 23), NIGP 83427, ×6 (20), NIGP 83428, ×4.5 (22), NIGP 83429, ×5 (23); referred to Lotagnostus (Lotagnostus) punctatus by Lu and Lin (1984, pl. 3, figs. 8 and 9), from the Lotagnostus punctatus Zone, near Jiangshan and Changshan, western Zhejiang, China. (24–26) Exoskeleton (24), cephalon (25), and pygidium (26), XTR T1489, ×10, XTR T1484, ×11, XTR T1496, ×7; referred to Lotagnostus punctatus xinjiangensis by Xiang and Zhang (1985, pl. 10, figs. 4a, 9, and 11), from the Lotagnostus punctatus Zone, Guozigou, western part of northern Tianshan, Xinjiang, China. (27) Exoskeleton, XTR T030, ×5; described originally as the holotype of Lotagnostus xinjiangensis by Zhang (1981, pl. 55, fig. 9), from the upper part of Nanhuishan Group (Upper Cambrian of historical usage), near Shanshan, Xinjiang, China.. (Cow Head Group) of western Newfoundland as Lotagnostus americanus. The illustrated cephala show that considerable variation in expression of the scrobiculae, from nearly effaced to well-impressed, exists within this species. Salter (1864) described an Agnostus americanus-like pygidium from Wales under the name Agnostus trisectus. The pygidium was poorly preserved, and the species concept has been based on the well preserved material illustrated by Westergård (1922, pl. 1, figs. 11 and 12). However, refigured type material and additional material of L. americanus from Canada (Rasetti, 1944; Ludvigsen et al., 1989) show that Lotagnostus trisectus (sensu Westergård, 1922) is indistinguishable from the species described earlier from North America (Billings, 1860). Previously several specimens from Canada were also assigned to L. trisectus (Matthew, 1894, 1903; Westergård, 1922, p. 193). Although there may be some uncertainty as to whether the holotype of L. trisectus (Shergold and Laurie, 1997, fig. 218.1c) is conspecific with L. americanus, there is no doubt that the other specimens that were assigned subsequently to L. trisectus should be referred to L. americanus. Ludvigsen et al. (1989, p. 12) argued that Lotagnostus asiaticus Troedsson, 1937 from the Torsuqtagh Formation of Kuruktagh (eastern Tianshan region, China), Lotagnostus punctatus Lu, 1964 from the Siyangshan Formation of western Zhejiang, China, and Lotagnostus obscurus Palmer,. 1955 from the “Pogonip Group” of Nevada, are all junior synonyms of L. americanus. We concur with that assignment. A cephalon described as Goniagnostus verrucosus by Rusconi (1951) was transferred to Lotagnostus by Bordonaro (1985), and was subsequently regarded as a junior synonym of L. trisectus by Shergold et al. (1990) and Tortello and Bordonaro (1997). We concur with those assessments, and now assign the specimens to L. americanus. Lotagnostus americanus is a distinctive species of agnostoid trilobite characterized principally by a moderately wide axis that is longitudinally and transversely divided into three distinct parts, distinctive scrobiculae on the pleural areas, and a pair of tiny marginal spines at the posterolateral corners of the pygidium. The type suite of L. asiaticus shows a range of variation in the expression of scrobiculae on the surface, and the holotype from Troedsson’s (1937, pl. 1, fig. 10a, b) figures appears to be nearly effaced. However, reexamination of the specimen, which is reposited in the Nanjing Institute of Geology and Palaeontology (NIGP) collections, shows that the specimen is quite weathered. Prior to weathering, the specimen may have had well-expressed scrobiculae. Geographic and stratigraphic distribution: Lotagnostus americanus has a relatively short stratigraphic range and commonly co-occurs with the polymerid trilobite Hedinas-.

(7) Two Cambrian agnostoid trilobites, Agnostotes orientalis (Kobayashi, 1935) and Lotagnostus americanus (Billings, 1860). pis in outer-shelf lithofacies. At present, specimens referred to L. americanus are known from Quebec, Newfoundland, Nevada, the Precordillera terrane of Argentina, Sweden, and China (eastern Tianshan region, Zhejiang, Hunan, and Anhui), Australia (Tasmania), England, and Wales. In Sweden, L. americanus (as reassigned here from L. trisectus) ranges from the lower part of the Peltura minor Zone to the middle of the Peltura scarabaeoides Zone (Ahlberg, 2003). In China, L. americanus, as reassigned here, is restricted to the Lotagnostus americanus [=L. punctatus] Zone in western Zhejiang and to L. americanus [=L. punctatus]– Hedinaspis regalis Zone in northwestern Hunan and Xingjiang. ACKNOWLEDGMENTS: We thank Duck K. Choi and John H. Shergold for their review of the manuscript. 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