ARTICLE. Early Devonian graptolites and graptolite biostratigraphy, Arctic Islands, Canada

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1 1097 ARTICLE Early Devonian graptolites and graptolite biostratigraphy, Arctic Islands, Canada Alfred C. Lenz Introduction Abstract: The Early Devonian graptolite fauna of the Arctic Islands comprises the highest species content (17 species) in the world. In spite of this richness, no new species have been recognized; instead already-existing species, scattered around the then-known continents, suggest that relatively complete cosmopolitanism held sway for graptolites. Canadian Arctic biozonation is very similar to schemes elsewhere, consisting of the uniformis and hercynicus biozones in the Lochkovian, falcarius in the lower Pragian, and an expanded yukonensis Biozone in the upper Pragian and the lower Emsian. Three genera and 17 species are recognized: Monograptus (microdon cf. microdon, microdon curvatus); Neomonograptus (cf. atopus, aequabilis, bardoensis, falcarius, notoaequabilis); and Uncinatograptus (birchensis, craigensis, hercynicus, langgunensis, parangustidens, subhercynicus, telleri, thomasi, uniformis, yukonensis). Résumé : Malgré le fait que la faune à graptolites du Dévonien précoce de l archipel Arctique présente la plus grande richesse spécifique (17 espèces) du monde, aucune nouvelle espèce n y a été identifiée, la présence d espèces déjà identifiées un peu partout sur d autres continents semblant indiquer que les graptolites faisaient preuve d un cosmopolitisme relativement complet. La biozonation dans l Arctique canadien est très semblable aux schémas décrits dans d autres régions, comprenant notamment les biozones à uniformis et hercynicus dans le Lochkovien, à falcarius dans le Praguien inférieur, ainsi qu une biozone à yukonensis élargie dans le Praguien supérieur et l Emsien inférieur. Trois genres et dix-sept espèces sont recensés, à savoir : «Monograptus» (microdon cf. microdon, microdon curvatus), Neomonograptus (cf. atopus, aequabilis, bardoensis, falcarius, notoaequabilis) etuncinatograptus (birchensis, craigensis, hercynicus, langgunensis, parangustidens, subhercynicus, telleri, thomasi, uniformis, yukonensis). [Traduit par la Rédaction] Early Devonian graptolites were routinely recovered by Geological Survey of Canada (GSC) during field-mapping projects in the Arctic Islands in the late 1970s and early 1980s, and a few species were listed in their reports (e.g., Kerr 1974; Jackson et al. 1976; Robson 1984), but there were no comprehensive studies of the graptolite faunas. By comparison, systematic studies were being routinely carried out in northern Yukon and adjacent Northwest Territories during the 1970s and 1980s (e.g., Lenz and Jackson 1971; Jackson and Lenz 1972; Jackson and Lenz in Jackson et al. 1978; Lenz 1988a, 1988b). Simultaneously, similar comprehensive studies were going on elsewhere in the world; in particular, and citing only a few examples, Jaeger 1959, 1979, 1988 in Central Europe; Koren 1971, 1974b, 1978a, in Central Asia and Pai-Khoi, northernmost Urals; and Porębska 1982, in southwestern Poland. More recently, similar studies were carried out in Yunnan, south China (Chen and Quan 1992; Zhang and Lenz 1998). The present study is the first comprehensive one of an entire suite of Early Devonian graptolites from a huge area (Fig. 1) and demonstrates that the Arctic Islands are the host for at least 17 species, all of which were already known from scattered localities in the world and together constitute the largest species diversity of Early Devonian graptolites in any one region globally (Fig. 2). Biostratigraphy The Lower Devonian biozonation of the Arctic Islands sequences is basically unchanged from that shown in Jackson et al. (1978) and Lenz (1988a) for northern Yukon and is readily comparable to uppermost Silurian and Lower Devonian biozonation schemes globally (Fig. 3). Lower Devonian graptolite species are widely distributed globally, although species such Uncinatograptus birchensis, Neomonograptus bardoensis, N. notoaequabilis, and U. subhercynicus, occur through lesser, greater, or different biostratigraphic ranges in comparison with those of the same species elsewhere in the world. This difference might be attributable to three factors: the sampling of an area that is orders of magnitude larger than elsewhere globally, a large number of sections representing different lithologies, and, presumably, many different environments. Biozones are based on the lowest occurrences of the eponymous species i.e., they are interval biozones. Interestingly, Linograptus is completely absent from all the Arctic Lower Devonian collections. By comparison, it is well represented between the transgrediens and uniformis biozones e.g., Germany and southwestern Poland and, following terminology of Jaeger (1979), was termed the linograptid interregnum by Porębska and Sawłowicz (1997). The interval of the earliest occurrence of U. birchensis in the Arctic may coincide with the linograptid interregnum and is so shown in Fig. 3. Uncinatograptus birchensis Biozone This biozone was proposed by Lenz and Kozłowska-Dawidziuk (2004) in the study of Ludlow and Pridoli graptolites of the Arctic, where it was recognized that the interval was clearly above the level of Neocolonograptus transgrediens, the accepted top of the Silurian graptolite biostratigraphic scheme (Koren et al. 1995) but below the first occurrence of U. uniformis, the species that marks the base of the Lower Devonian internationally. This study demonstrates that U. birchensis ranges from the uppermost Pridoli to the lower Pragian (Fig. 4). In Nevada, the type locality for the species, U. birchensis, ranges from well below to a short distance into the uniformis Biozone (Berry and Murphy 1975). Received 24 April Accepted 5 August Paper handled by Associate Editor Jisuo Jin. A.C. Lenz. Department of Earth Sciences, Western University Ontario, London, ON N6A 5B7, Canada. for correspondence: aclenz@uwo.ca. Can. J. Earth Sci. 50: (2013) dx.doi.org/ /cjes Published at on 20 August 2013.

2 1098 Can. J. Earth Sci. Vol. 50, 2013 Fig. 1. Index map of a portion of the Arctic Islands, showing locations of graptolite sections. 1, Polar Bear Pass; 2, Moses Robinson River; 3, Stuart River; 4, Cut Through Creek; 5, Twilight Creek; 6, Grant Point; 7, Humphries Hill; 8, Cape Sir John Franklin; 9, Cape Lyons; 10, Eidsbotn River; 11, Ptarmigan Lake; 12, Strathcona Fiord. Squares are key sections. Uncinatograptus uniformis Biozone Only one of the sampled sections (Twilight Creek) yielded Uncinatograptus uniformis, the internationally agreed-upon marker for the base of the Devonian. At a second locality (Humphries Hill), the lowest Neomonograptus aequabilis was collected from probably the same stratigraphic position. Included also in the local biozonal assemblage is a long-ranging species, N. notoaequabilis, that occurs earlier in the Arctic than, for example, in Poland (Porębska 1982) or from the type species section in Thailand, where a Pragian age is suggested by Jaeger and Stein (in Jaeger et al. 1969). Based on its stratigraphic position in northern Yukon (Lenz 1988b), U. parangustidens, recovered from a single Arctic Islands outcrop, as well as U. subhercynicus also probably first occur in this biozone. Uncinatograptus hercynicus Biozone This biozone is among the most widespread and easily recognized globally, based solely on the index species. Among the local species making up the total fauna of this biozone are U. subhercynicus and U. birchensis. N. notoaequabilis and N. bardoensis are also almost certainly present in this biozone, as, for example, from the m interval of the Strathcona Fiord. Neomonograptus falcarius Biozone This biozone is recognizable by the presence of the index species. Species included in the interval include the uppermost levels for N. notoaequabilis, N. bardoensis, U. birchensis, and a first but rare occurrence of U. telleri, as in Poland (Porębska 1982), as well as Monograptus cf. microdon microdon.?neomonograptus fanicus Biozone This biozone, not presently recognized in the Arctic Islands, is mentioned because the index species might be expected in the Arctic Islands in view of its occurrence in northern Yukon (Lenz 1988b), and a single synrhabdosome from Devon Island was identified as N. fanicus (Jackson et al. 1976). The authors neither describe nor illustrate a dorsal sicular process, making the identification questionable. Uncinatograptus yukonensis Biozone The yukonensis Biozone is the most widely recognized Lower Devonian graptolite biozone globally. It is also one with a species diversity that is surprisingly high, considering that it is the last pre-extinction graptolite fauna in existence globally. Morphologically, U. yukonensis shows great variation, especially in the J shape of its rhabdosome, and, as a result, there have been a relatively large number of erected species names, especially those by Chinese workers (e.g., Wang 1977; Ni and Jiao 1983). Earlier, a biometric study (Lenz 1988a) of abundant material from northern Yukon showed that the J shape ranged from 20 to 110 but averaged about 50 ; accordingly, the degree of curvature is not considered a reliable criterion for species distinction. A second problem is the species composition of the yukonensis Biozone. Koren (1975) recorded a long interval with craigensis below yukonensis; Churkin et al. (1970) recorded yukonensis interbedded with craigensis and overlain by pacificus; Jaeger (1970) recorded pacificus above yukonensis; and Jaeger (1979) and Lenz (1988b) recorded U. thomasi below yukonensis (Fig. 3). In each case, the stratigraphic position of the various species has led to a yukonensis Biozone of restricted species content. In the Twilight Creek and Polar Bear Pass sections (Fig. 4), however, all of the species noted earlier in the text are completely intermixed, as in northern Yukon (Lenz 1988a). It is concluded, then, that a single expanded yukonensis Biozone is fully justified for the entire upper Pragian and lower Emsian interval. Paleobiogeography Plotting graptolite distributions on an Early Devonian paleogeographic map (Fig. 5) demonstrates that the vast majority of

3 Lenz 1099 Fig. 2. Species diversity of the Arctic Islands Lower Devonian graptolites compared with those of the main coeval regions in the world. Not listed are species such as Monograptus angustidens, M. praehercynicus, M. kayseri, and M. ramstalensis, all described in Jaeger (1959) but not occurring in Arctic Canada. Sources of information for each region: Yukon: Jackson and Lenz, 1962; Lenz and Jackson, 1971, Jackson et al. 1978; Lenz, 1988a, 1988b. Nevada: Berry and Murphy, Poland: Porębska, Germany: Jaeger, 1959, Yunnan: Ni and Jiao, 1983; Chen and Quan, Czech Republic: Přibyl, 1940, 1941; Bouček, Southern Alaska: Churkin et al. 1969, South Australia: Jaeger, 1966; Rickards and Wright, Spain: Lenz et al Xizang (Tibet): Mu and Ni, 1975; Mu and Ni, Guangxi: Wang, Central Asia: Obut, 1972; Koren, 1978a. Thailand: Jaeger et al Burma: Jaeger, Malaysia: Jones, Morocco: Willefert, 1962, 1963; Planchon, 1964; Hollard and Willefert, Ukraine: Koren, 1968, Tsegelnyuk, Gaspé, Quebec: Boucot et al., 1967; Lenz, Pai Khoi: Koren, 1969, 1971, graptolite sites reside within the 30 N and 30 S parallels of latitude; these include North America, most of northeastern Europe (Baltica), south China, southeastern Australia, Malaysia, Burma, and Thailand. Nevertheless, they are found in a few regions, such as northern Africa (Morocco) and probably some parts of Central Asia and Gondwanan Europe (Czech Republic, Iberia, and southwest Poland) that are outside the 30 paleolatitude lines, demonstrating that Lower Devonian graptolites had, at least, some tolerance across a moderate temperature range. Furthermore, in a comparison of the Arctic diversity with that of the four regions with the highest diversity (Yukon, Poland, Yunnan, and Central Asia; Fig. 2), it is evident that the great distances between the Arctic and any one of the cited regions had, in general, little influence. It is evident, then, that diversity fluctuations were relatively minor and that cosmopolitanism was moderately well established and persistent among the Early Devonian graptolites, in contrast to, for example, Lower Devonian brachiopods in Johnson (1971), rugose corals in Oliver and Pedder (1979), or mid-wenlock graptolites (Lenz et al. 2012). In past studies (e.g., Jaeger 1988; Lenz in Lenz et al. 1993), it was suggested that the perceived much lower diversity around the Lochkovian Pragian boundary suggested provincialism. The present summation of data from especially southwestern Poland (Porębska 1982); northern Yukon (Lenz 1988a); Pai-Khoi, northernmost Urals (Koren 1971); Central Asia (Koren 1975, 1978a); and this study paint a rather different picture in overall species diversity. A tabulation biozone by biozone, shows the following: uniformis Biozone: 11 species; hercynicus Biozone: 11 species; falcarius Biozone: seven species; yukonensis Biozone: seven species. Further, the fact that no new species were recognized in this study and ones already recognized were widely scattered through the Early Devonian continents and terranes (Fig. 5) suggests that oceanic currents were very long ranging and relatively unobstructed. Systematic paleontology All figured specimens described in this publication are housed in the National Type Collection of Invertebrate Fossils of the GSC,

4 1100 Can. J. Earth Sci. Vol. 50, 2013 Fig. 3. Correlation of Lower Devonian graptolite biostratigraphic schemes. Only regions with more or less full ranges of biozones are compared. PRID., Pridoli; L. EMS., lower Emsian. Fig. 4. Correlation of all major stratigraphic sections from Arctic Canada. Only those with at least a partial sequence are shown. Positions of some individual collections are in the best guess category. For single collections i.e., spot samples see Appendix A. Ottawa, Ontario K1A 0E8, and are assigned GSC numbers. The total fauna, their localities, and the number of specimens of each species are listed in Appendix A. Locality abbreviations (e.g., GP96, SF93) are also spelled out in Appendix A. Early Devonian monograptids carry few distinguishing or unique features: presence or absence of rhabdosomal dorsal curvature, narrow to broad V-shaped sicula with or without a dorsal sicular process, and stronger to weaker uncinatiform or monoclimacid thecae. The separation of the two genera Uncinatograptus Tsegelnyuk, 1976, and Neomonograptus Mu and Ni, 1975, basically hinges on a single morphological criterion: the composition or makeup of thecal hoods; to wit, Uncinatograptus possesses strong thecal hoods proximally that slowly diminish in size distally, whereas Neomonograptus has well-developed thecal hoods for the first one to several uncinatiform thecae, but the remaining distal ones are basically monoclimacid. Unlike Koren (1979) and Porębska (1982), the development of the sicula is here considered to be an evolutionary secondary and recurring apomorphic structure, useful only for species. Form genus Monograptus Geinitz, 1852 TYPE SPECIES: Lomatoceras priodon Bronn, 1834, p. 55, pl. 1, fig. 13. REMARKS: The genus Monograptus has, for generations, been employed for the vast majority of uniserial graptolites (Bulman 1970). This practice has been largely disappearing, and many previously

5 Lenz 1101 Fig. 5. Early Devonian paleogeographic map, showing position of the various terranes from the paleoequator perspective and approximate position of graptolite sections (small white circles). (Early Devonian paleogeographic map after Ron Blakely, NAU Geology.) BAL, Baltica; GON, Gondwana; Kaz, Kazakh; Mon, Mongol; NAM, North America; O, ocean; Or, Orogen; SIB, Siberia. proposed genera are again being utilized and legitimized, and new ones are being erected. The genus Monograptus is still used systematically for graptolites with hooked thecae (as in M. priodon) or as a form genus for those whose thecae are not fully understood, as in the following two subspecies. Monograptus microdon cf. microdon Reinh. Richter, 1875 Figures 6B.1 6B.4 cf Monograptus microdon Reinh. Richter, p. 268, pl. 8, figs cf Monograptus microdon microdon Reinh. Richter, Jaeger, p. 107, pl. 1, fig. 6; pl. 5, figs. 7 13; text-fig. 17g. cf Monograptus microdon Reinh. Richter, Berry and Murphy, p. 54, pl. 3, fig. 3. cf Monograptus microdon microdon Reinh. Richter, Porębska, fig. 17/1 17/5.?1992 Monograptus microdon Reinh. Richter, Chen and Quan, p. 183, figs. 3C, 3D, 4C, 4D.?1998 Monograptus microdon Reinh. Richter, Zhang and Lenz, p. 355, figs ; 4.1. COLLECTION SITES OF STUDY MATERIAL: Grant Point (GP96, 181 m); eight specimens only. TYPE LOCALITY: Ober Graptolithenschiefer, Hohlweg bei Creunitz, Thuringia, Germany. ARCTIC BIOSTRATIGRAPHIC RANGE: Probably lower Pragian, falcarius Biozone, or the upper Lochlovian, hercynicus Biozone; occurring stratigraphically above U. hercynicus but below N. cf. atopus. GLOBAL OCCURRENCE: (Of M. microdon microdon.) Poland, Nevada, Germany, Yunnan, Czech Republic, Urals, Sardinia, Austria,?Yukon. DESCRIPTION: Rhabdosome diminutive in both length and width, gently ventrally curved through thecal levels of six to seven, straight thereafter. Proximal end narrow, 0.46 mm including thecal hood, widening steadily to the distal limit of ventral curvature, then parallel or narrowing slightly above that level. Maximum width mm. Thecae climacograptid, ventral walls parallel to nema, thecal apertures small, U shaped, visible throughout, topped by very short, down-curved selvages. Thecal spacing 7 6 in 5 mm. Sicula 1.38 mm, with slight ventral curvature to its dorsal wall, apex slightly above level of theca 1. REMARKS: In comparison with that of, e.g., Jaeger (1959); Berry and Murphy (1975); Porębska (1982), and Zhang and Lenz (1998), the Arctic material compares reasonably well with metrics, differing in having a consistent ventral curvature rather than being straight throughout. Thus, the Arctic material is tentatively compared with Monograptus microdon microdon. In comparison with M. microdon silesicus Jaeger, 1959, the dorsal curvature of the rhabdosome of the latter, as well as its weaker ventral curvature of the sicula, distinguishes the two subspecies, whereas that identified as Monograptus ex gr. microdon in Lenz (1972) from the Gaspé region, Quebec, compares favourably with M. microdon silesicus. Monograptus microdon curvatus Lenz and Kozłowska-Dawidziuk, 2004 Figures 6A.1 6A Monograptus microdon curvatus Lenz and Kozłowska- Dawidziuk, p. 27, pl. 39, figs. 9 12; pl. 45, figs. 18, COLLECTION SITES OF STUDY MATERIAL: Strathcona Fiord (SF93, 488 and 490 m); Grant Point (GP96, 130 m); Eidsbotn River, Devon Island (GSC locality C146446). The four specimens in the last named collection constitute topotypes. TYPE LOCALITY: Eidsbotn River, Devon Island (GSC locality C146446). ARCTIC BIOSTRATIGRAPHIC RANGE: U. birchensis Biozone and lower Lochkovian, uniformis Biozone. GLOBAL OCCURRENCE: At present, found only in Arctic Canada. REMARKS: In comparison with the three previously known subspecies, M. microdon microdon, M. microdon silesicus Jaeger, 1959, and M. microdon aksajensis Koren, 1983, the Arctic species is readily distinguishable by the relatively strong and persistent dorsal curvature of its rhabdosome. Thecae are spaced in 5 mm, and width of rhabdosome is mm proximally and mm distally. Genus Neomonograptus Mu and Ni, 1975, emended TYPE SPECIES: Monograptus atopus Bouček, 1966, p. 163, text-fig. 1C 1D; text-fig. 2, figs EMENDED DIAGNOSIS: Rhabdosome with straight to moderate dorsal curvature proximally. Theca 1 robust and strongly hooked, concealing aperture; thecae 2 4 with modest development of thecal hoods in some specimens; distally very short, horizontally directed selvages, sometimes not discernible. Ventral walls and

6 1102 Can. J. Earth Sci. Vol. 50, 2013 Fig. 6. (A) Monograptus microdon curvatus Lenz and Kozłowska-Dawidziuk, , GSC137314, GP96, 130 m; 2, GSC137315, GSC locality C146446, sicula preserved; 3, GSC137316, C146446; 4, GSC137317, SF93, 488 m; 5, GSC137318, SF93, 488 m; 6, GSC137319, SF93, 490. All 6.5. (B) Monograptus microdon cf. microdon Reinh. Richter, , GSC137310, GP96, 181 m; 2, GSC137311, partial scalariform orientation, showing thecal hoods; 3, GSC137312, GP96, 181 m, proximal end missing; 4, GSC137313, proximal end missing. All 6.5. (C) Neomonograptus cf. atopus (Bouček, 1966). 1, GSC137323, GP96, m; 2, GSC137324, GP96, m; 3, GSC137325, GP96, m. All 5.0. (D) Neomonograptus aequabilis (Přibyl, 1940). 1, GSC137320, HH94, 204 m; 2, GSC137321, HH94, 204 m; 3, GSC137322, HH94, 204 m. All 5.0. [Note change in scale.]

7 Lenz 1103 apertures of thecae climacograptid or monoclimacid. Sicula a normal to very broad triangle, with or without well-developed apertural dorsal tongue. Neomonograptus aequabilis (Přibyl, 1941) Figures 6D.1 6D Pristiograptus aequabilis Přibyl, p. 8, pl. 1, figs Monograptus aequabilis (Přibyl), Jaeger, p. 102, pl. 1, fig. 8; pl. 4, fig. 3; pl. 5, figs. 1 5; text-fig. 17a, b Monograptus aequabilis (Přibyl), Boucot et al., p. 10, pl. 3, figs Monograptus aequabilis aequabilis (Přibyl), Churkin et al., p. 10, pl. 3, text-figs. 9B, 9I Monograptus aequabilis (Přibyl), Jackson and Lenz, textfigs. 1A, 1C, 1K, 1L Monograptus aequabilis aequabilis (Přibyl), Lenz, p. 1149, textfig. 2C.?1972 Monograptus aequabilis gaspesiensis Lenz, p. 1150, textfigs. 2A, 2B, 2F Monograptus aequabilis (Přibyl), Jaeger, table 1, fig a Monograptus aequabilis (Přibyl), Koren, p. 121, pl. 1, figs. 4, 5; text-fig. 5a 5e Monograptus aequabilis aequabilis (Přibyl), Porębska, p. 188, fig. 26/1 26/ Monograptus aequabilis (Přibyl), Zhang and Lenz, p. 355, textfigs ; 4.6. COLLECTION SITES OF STUDY MATERIAL: Humphries Hill (HH94, 204 m), 10 specimens, three of which are moderately well preserved. TYPE LOCALITY: Lejškov, near Suchomasty, Czech Republic, uniformis Biozone. ARCTIC BIOSTRATIGRAPHIC RANGE: Most probably lower Lochkovian, uniformis Biozone by comparison with Yukon sequences (Jackson and Lenz 1972; Lenz 1972) to possibly upper Lochkovian, hercynicus Biozone (cf. Porębska 1982; Zhang and Lenz 1998) in which N. aequabilis is shown to range through the uniformis and hercynicus biozones. GLOBAL OCCURRENCE: Yukon, Poland, Nevada, Germany (Thuringia), Yunnan (southern China), Central Asia, southern Alaska, southeastern Australia, Spain, Czech Republic, Gaspé region (Quebec), Sardinia,?Morocco. DESCRIPTION: Rhabdosome more or less straight or slightly dorsally curved in the region of thecae 1 4, longest specimen about 10 mm long. Theca 1 decidedly broader and hood more down-curved than all others, thecae 2 4 bearing smaller, uncinatiform hoods; remainder of thecae with short to very short selvages. Ventral walls of thecae inclined 0 o 20 o to nema, thecal apertures large, thecae climacograptid or monoclimacid in outline. Interthecal septa sigmoidal, main part inclined 30 o 40 o to nema, basal portion not overlapping underlying theca. Width increasing slowly, width across theca mm with hood and mm without hood; at level of theca 5, 1.3 mm with hood and mm without hood; distally mm. Thecal spacing in 5 mm proximally and in 5 mm distally (two specimens). Sicula with gentle ventral curvature, width mm, apertural region with modest dorsal process. REMARKS: The Arctic specimens compare very well with the type aequabilis in most respects, differing primarily in having more closely spaced thecae (approximately 6.5 in 5 mm proximally, compared with in 5 mm), as well as width differences ( mm, as compared with maximum widths of mm for most specimens globally). The latter difference is probably explainable by differences in length i.e., only about 10 mm length for the Arctic specimens versus specimens two to four times the length elsewhere. Gaspé specimens, identified as a new subspecies (Lenz 1972, p. 1150), compare very favourably with the Arctic specimens in thecal spacing but are considerably narrower, even in specimens up to 40 mm long. Furthermore, while most of the specimens collected from Central Asia are typical in their widths, Koren (1978a, p. 123) comments that some long specimens attain widths of no more than 1.3 mm. The Arctic specimens, then, are still within the range of variation of the typical aequabilis. Neomonograptus cf. atopus (Bouček, 1966) Figures 6C.1 6C.3 cf Monograptus atopus Bouček, p. 163, text-fig. 1C 1D; textfig. 2, figs cf Neomonograptus himalayensis, Mu and Ni, p. 19, pl. 5, figs. 4 11; pl. 8, fig. 8a; text-figs. 1a, 1b, 2a. cf Neomonograptus atopus var. rigidus Mu and Ni, p. 21, pl. 6, figs. 3 6, 11, 12, text-figs. 1d, 1e, 2b. cf Neomonograptus latus Mu and Ni, p. 22, pl. 5, figs. 1 3; text-fig. 2c. cf Monograptus atopus Bouček, Jaeger, p. 249, pl. 1, figs. 1 5; text-figs. 4a 4d. cf Neomonograptus himalayensis Mu and Ni, Mu and Ni, p. 6, pl. 3, figs. 2, 3, 3a; text-fig. 1d. cf Neomonograptus rigidus Mu and Ni, Mu and Ni, p. 7, pl. 3, figs. 5, 5a; text-fig. 1e. cf Neomonograptus latus Mu and Ni, Mu and Ni, p. 7, pl. 3, Fig. 6; pl. 4, figs. 3, 6. COLLECTION SITES OF STUDY MATERIAL: Grant Point (GP96, m), but only four specimens, three being moderately well preserved. TYPE LOCALITY: The village of Svatý Jan pod Skalou, Dvorce Prokop Limestone, Czech Republic. ARCTIC BIOSTRATIGRAPHIC RANGE: Most probably Pragian and, possibly, lower Emsian, yukonensis Biozone; not associated with any other species but situated 24.5 m above U. hercynicus in the Grant Point section. GLOBAL OCCURRENCE: Presently known only from Arctic Canada, but typical atopus has been recovered in the Czech Republic (N. atopus), Burma (N. atopus), and Xizang (Tibet) (N. himalayensis, N. rigidus, N. latus), all in the yukonensis Biozone. DESCRIPTION: Rhabdosome essentially straight throughout, but gentle dorsal curvature involving sicula and first two or three thecae, a gentle ventral curvature at the level of thecae 4 8, and straight thereafter. Width across theca 1 about 1.25 mm with hood and mm without hood; mm across theca 5 with hood and mm without hood; and mm distally. First thecal hood prominent, next one or two much less so, and remainder mere selvages. Thecal spacing in 5 mm proximally and in 5 mm distally. Thecae climacograptid, with deep, horizontal apertures, ventral walls more or less parallel to nema. Sicula trumpet shaped, wide to unusually wide across aperture, mm (three specimens only), length 1.6 mm (one specimen), without dorsal apertural tongue. REMARKS: In his discussion of the Lower Devonian monograptids of Burma, Jaeger (1983) observed that he could recognize no discernible morphological difference between the type of atopus Bouček, 1966, and N. himalayensis, rigidus, and latus, all by Mu and Ni (1975), so they were synonymized by him. The same conclusion is reached in this paper, and they all are put into synonymy with N. atopus. Consequently, the type species for Neomonograptus should be cited as N. atopus (Bouček 1966). Typical of the species is the considerable width across theca 1, very gradual widening distally, and the very broad, triangular shape of the sicula. In almost all features, the Arctic material bears a close resemblance to N. atopus, except for the more closely spaced thecae (6.5 8 in 5 mm proximally and in 5 mm distally, compared with in 5 mm for the Czech and Chinese material).

8 1104 Can. J. Earth Sci. Vol. 50, 2013 Fig. 7. (A) Neomonograptus bardoensis (Porębska, 1982). 1, GSC137326, SF93, 477 m; 2, GSC137327, SF93, 477 m; 3, GSC137328, SF93, 522 m; 4, GSC137329, GP96, 151 m. (B) Neomonograptus falcarius (Koren, 1969). 1, GSC137330, GSC locality C207175; 2, GSC137331, C207176; 3, GSC137332, C207176; 4, GSC137333, C207176; 5, GSC137334, C All 5.0. Neomonograptus bardoensis (Porębska, 1982) Figures 7A.1 7A Monograptus aequabilis bardoensis Porębska, p. 194, figs. 28/1 28/ b Monograptus aequabilis bardoensis Porębska, Lenz, p. 362, pl. 1, figs. K O; text-figs. 3A 3F. COLLECTION SITES OF STUDY MATERIAL: Strathcona Fiord (SF93, 477, 522, and 524 m), Grant Point (GP96, 151, 155?, 171, and 175? m), Humphries Hill (HH94, 210 m?), Twilight Creek (TC88, #37: 540 m), Cut Through Creek (GSC C207058, 419 m). TYPE LOCALITY: Żdanów, Bardo Mountains (Sudetes), Poland; from falcarius, fanicus, and lower craigensis biozones (lower Pragian). ARCTIC BIOSTRATIGRAPHIC RANGE: Lower Lochkovian, uniformis Biozone and upper Lochkovian, hercynicus Biozone; possibly lower Pragian. GLOBAL OCCURRENCE: Yukon, Poland. DESCRIPTION: Rhabdosome distally straight from about level of theca 3 or 4; up to 40 mm long. Proximal-most region with gentle dorsal curvature, curvature accentuated by moderate dorsal curvature of sicular dorsal wall. Rhabdosome widening slowly from theca 1 to level of theca 5, followed by extremely slow widening distally. Width across theca 1 measures mm with thecal hood and mm without hood; across theca 5, width mm with hood and mm without hood; distally mm. Theca 1 generally larger and more robust than the succeeding two to three thecae, with moderate-size hoods; remainder of thecae with only very minor, or no, selvages. Thecal spacing 5 7 in 5 mm proximally, 4 6 in 5 mm distally. Distal thecae climacograptid in profile, ventral walls 0 o 20 o to nema; apertures large, U-shaped openings. Interthecal septum weakly sigmoidal, not overlapping previous septum. Sicula widening distally and trumpet-like, dorsal walls strongly curved, apertural rim straight or concave, without a dorsal tongue. REMARKS: Distinctive of this species the relatively gentle dorsal curvature of the proximal region, a moderately wide sicula that is without a dorsal tongue. It bears a moderately strong resemblance to N. fanicus and N. notoaequabilis but lacks a dorsal sicular tongue found in those two species. Neomonograptus falcarius (Koren, 1969) Figures 7B.1 7B Monograptus falcarius Koren, p. 1326, figs. 2, Monograptus falcarius Koren, Koren, p. 6, pl. 1, figs Neomonograptus falcarius (Koren ), Xiang et al., p. 131, pl. figs a Monograptus falcarius Koren, Koren, p. 121, pl. 1, figs. 8, 9; pl. 2, fig. 4; text-figs. 4i 4k, 4m 4q Monograptus falcarius Koren, Porębska, p. 166, figs. 21/1 21/ Monograptus falcarius Koren, Zhang and Lenz, p. 358, figs , 4.2, COLLECTION SITES OF STUDY MATERIAL: Humphries Hill (GSC localities C207175, m; C207177, m; C207176, m). TYPE LOCALITY: Livanov Cape Formation, near Amderma Village, Pai-Khoi, northernmost Urals. ARCTIC BIOSTRATIGRAPHIC RANGE: Probably Pragian, falcarius Biozone. GLOBAL OCCURRENCE: Poland, Central Asia, Pai-Khoi (northernmost Urals), Yunnan (southern China), Czech Republic.

9 Lenz 1105 Fig. 8. (A) Uncinatograptus birchensis (Berry and Murphy, 1975). 1, GSC137340, HH94, 219 m; 2, GSC137341, GP96, 130 m, partial scalariform view showing thecal hoods; 3, GSC137342, SF93, 488 m; 4, GSC137343, SF93, 488 m. All 5.0. (B) Neomonograptus notoaequabilis (Jaeger and Stein, in Jaeger et al. 1969). 1, GSC , SF93, 513 m; 2, GSC137336, HH94, 219 m; 3, GSC137337, SF93, 490 m; 4, GSC137338, SF93, 513 m; 5, GSC137339, GSC locality C DESCRIPTION: Rhabdosome with moderately strong dorsal curvature through proximal four to five thecae, accentuated by asymmetrical sicula that widens rapidly along its dorsal side; remainder of rhabdosome relatively straight. Rhabdosome mm across theca 1 hood and mm between hoods; mm across theca 5; mm distally. Thecae biform; theca 1 slightly to markedly more robust, succeeding three to four thecae with reasonably developed thecal hoods; distal thecae with small, horizontal selvages, thecal ventral walls inclined 0 o 20 o to nema. Thecal spacing in 5 mm proximally, about 5 in 5 mm distally. Sicula strongly flaring toward aperture, broadly triangular, 2 mm long (one specimen), mm in width, without dorsal process. REMARKS: The Arctic material of Neomonograptus falcarius bears a similarity to U. hercynicus, especially in its sicula, but differs in its possession of a moderately strong dorsal curvature in the proximal region of its rhabdosome and the strongly biform thecae as compared with strong to moderately strong thecal hoods throughout in hercynicus. It compares much more closely to N. fanicus with its strongly biform thecae and much more pronounced dorsal curvature of the rhabdosome but lacks a sicula a dorsal sicular process. The Arctic specimens compare favourably with the Pai-Khoi material in their thecal spacing. Neomonograptus notoaequabilis Jaeger and Stein (in Jaeger et al. 1969) Figures 8B.1 8B.5?1964 Monograptus belketaiefensis Planchon, p. 2, figs. a c Monograptus aequabilis (Příbyl), Jaeger, p. 398, pl. 41, figs. 1, 2; text-fig. 1d Monograptus aequabilis notoaequabilis Jaeger and Stein in Jaeger et al., p. 182, pl. 15, figs. A, B; text-figs. 1E, 1F Monograptus aequabilis amdermaensis Koren, p. 1327, figs. 2, Monograptus aequabilis notoaequabilis Jaeger and Stein (in Jaeger et al. 1969), Churkin et al., p. 194, figs. 9C, 9J Monograptus aequabilis notoaequabilis Jaeger and Stein (in Jaeger et al. 1969), Koren, fig. 3D; figs. 4A 4C, 4E. 1974a Monograptus aequabilis notoaequabilis Jaeger and Stein (in Jaeger et al. 1969), Koren, pl. 27, figs. 1 12; pl. 28, figs b Monograptus aequabilis notoaequabilis Jaeger and Stein (in Jaeger et al. 1969), Koren, pl. 26, figs Monograptus aequabilis notoaequabilis Jaeger and Stein (in Jaeger et al. 1969), Koren, p. 7, pl. 1, fig. 1; pl. 2, figs. 1 3; pl. 3, fig. 4; pl. 4, figs. 1, 2, 9; pl. 8, figs M. (Metamonograptus) aequabilis notoaequabilis Jaeger and Stein (in Jaeger et al. 1969), Wang, p. 199, pl. 2, figs. 9 11; pl. 3, figs. 1, a Monograptus aequabilis notoaequabilis Jaeger and Stein (in Jaeger et al. 1969), Koren, p. 123, pl. 1, fig. 6; text-figs. 5f, 5g. 1978b Monograptus aequabilis notoaequabilis Jaeger and Stein (in Jaeger et al. 1969), Koren in Sokolov and Garkovetz, pl. 65, figs. 1 3, Monograptus aequabilis notoaequabilis Jaeger and Stein (in Jaeger et al. 1969), Porębska, p. 190, text-figs. 27/1 27/16.?1992 Monograptus aequabilis (Příbyl), Chen and Quan, p. 182, figs. 3A, 3E, 4F. COLLECTION SITES OF STUDY MATERIAL: Strathcona Fiord (SF93, 490 and 513 m); Humphries Hill (HH94, 210 and 219 m); Humphries Hill (GSC localities C199157, C (154.8 m), C (170.3 m),

10 1106 Can. J. Earth Sci. Vol. 50, 2013 C (170.3 m)); Cut Through Creek, Bathurst Island (locality C207058, 419 m). TYPE LOCALITY: 20 Mile Quarry, Yarra Track, Victoria, Australia; Pragian. ARCTIC BIOSTRATIGRAPHIC RANGE: Lower Lochkovian, uniformis Biozone, upper Lochkovian, hercynicus Biozone?, probably lower Pragian, falcarius Biozone. GLOBAL OCCURRENCE: Yukon?, Poland, Central Asia, Pai-Khoi, Thailand, southern Alaska, southeastern Australia, Guangxi (southeastern China), Morocco?. DESCRIPTION: Rhabdosome essentially straight throughout its length. Width increasing slowly through space of first three to five thecae, very slowly thereafter. Width of first theca across thecal hood mm and between hoods; across theca 5, mm and mm between hoods; mm distally. Thecae biform, first three to five proximal thecae with strong hooks, the first theca being much more robust than the remaining; distal thecae climacograptid or monoclimacid in profile; ventral wall more or less parallel to nema, thecal aperture large, horizontal, with very short genicular selvages. Interthecal septa sigmoidal, main part inclined 30 o 40 o to nema, proximal portion not overlapping previous septum. Sicula simple cone to slightly widened near aperture, dorsal wall straight to weakly ventrally curved; up to 2.1 mm long, and mm wide; sicular aperture with well-developed dorsal tongue. REMARKS: Characteristic of this species is the more or less straight rhabdosome, an unusually robust theca 1, and a narrow cone-like sicula with a well-developed dorsal tongue, the latter distinguishing it from N. aequabilis. It bears some resemblance to N. fanicus but differs in its essentially straight rhabdosome and the relatively narrow cone shape to its sicula. Like N. bardoensis, it is basically straight throughout its length and has a similar thecal pattern but differs in possessing a narrow, dorsal tongue-bearing sicula. Genus Uncinatograptus Tsegelnyuk, 1976, emended TYPE SPECIES: Monograptus uncinatus Tullberg, 1883, pl. 1, figs. 24, 25. EMENDED DIAGNOSIS: Rhabdosome straight to dorsally curved proximally. Thecae range from robust thecal hoods that obscure apertures in the proximal one to two thecae; remainder of thecal hoods decreasing in strength slowly distally but always maintaining a presence; apertures visible distally owing to shortening of thecal hoods. Siculae ranging from a narrow cone to muchwidened V shaped, with or without dorsal processes. REMARKS: A number of graptolite workers have described some of the Upper Silurian and Lower Devonian graptolites as having uncinatus-style thecae (e.g., Jaeger 1966; Lenz and Jackson 1971; Berry and Murphy 1975; Koren 1983) but maintained the usage of the genus Monograptus without comment. Urbanek (1997) recognized the validity of Uncinatograptus but only at a subgenus level, and Koren (1979) had already recognized the two groups based on thecal structure as uniform (as in M. uniformis, M. yukonensis) and biform for members of Neomonograptus (as in N. falcarius, N. aequabilis). The prime difference between Uncinatograptus and Neomonograptus lies in the degree of development of the thecal hoods. For the former, well- to reasonably well-developed metathecal hoods are present throughout the entire rhabdosome (see Figs. 9.1, 9.2). Uncinatograptus birchensis (Berry and Murphy, 1975) Figures 8A.1 8A.4, 9.1, Monograptus birchensis Berry and Murphy, p. 48, pl. 1, figs. 1 4, 6, Monograptus birchensis Berry and Murphy, Lenz and Kozłowska-Dawidziuk, p. 26, pl. 28, figs ; pl. 39, figs. 1 3, 5, 6 [non figs. 4, 7, 8]; pl. 45, figs. 11, 12, Fig. 9. Two isolated specimens of Uncinatograptus birchensis (Berry and Murphy, 1975) from Arctic Canada, types GSC (1) and (2), to show uncinatiform thecal structures. From Lenz and Kozłowska-Dawidziuk (2004, pl. 28, figs. 11, 14). COLLECTION SITES OF STUDY MATERIAL: Strathcona Fiord, Ellesmere Island (SF93, 477, 488, and 537 m); Grant Point, Bathurst Island (GP96, 132 and 171 m); Humphries Hill, Bathurst Island (HH94, 198 and 219 m); and Twilight Creek, Bathurst Island (TC88, collections #35?, #36). TYPE LOCALITY: Birch Creek, section 2, central Nevada. ARCTIC BIOSTRATIGRAPHIC RANGE: Ranging from the highest Pridoli, post-transgrediens Biozone through to the upper Lochkovian hercynicus Biozone and, possibly, lower Pragian, falcarius Biozone. GLOBAL OCCURRENCE: Presently known only from the type region in Nevada and the Canadian Arctic Islands. DESCRIPTION: Rhabdosome for the most part straight, at least 20 mm long. Proximal region gently, but consistently, dorsally curved up to level of thecae 4 6. Proximal thecae with longer and stronger hooked metathecal hoods that are shorter and less incurved distally. In a few cases, very distal thecae are reduced to mere selvages. Ventral walls of thecae generally weakly inclined to rhabdosomal axis; interthecal septa strongly sigmoidal, never overlapping with those of underlying thecae, main portion of septum inclined about 30 o to rhabdosomal axis. Width increasing gradually from 0.9 to 1.1 mm and 0.6 to 0.8 mm across theca 1 with and without hoods, respectively; from 1.25 to 1.55 mm with hood

11 Lenz 1107 Fig. 10. (A) Uncinatograptus craigensis (Jaeger, in Churkin, Jaeger, and Eberlein 1970). 1, GSC137344, collection TC88, #48; 2, GSC137345, GSC locality C207194; 3, GSC137346, C (Note huge sicular dorsal process.); 4, GSC137347, C207237; 5, GSC137348, SF93, m. (B) Uncinatograptus hercynicus (Perner, 1899). 1, GSC137349, GP96, 173 m; 2, GSC137350, TC88, #42; 3, GSC137351, HH94, 243 m; 4, GSC137352, TC88, collection #39; 5, GSC137353, GP96, 171 m; 6, GSC137354, TC88, collection #39. All 5.0. and 1.0 to 1.35 mm without hood across theca 5; and from 1.6 to 2.4 mm with hood and 1.56 to 1.88 mm without hood distally. Thecal spacing is mm in 5 mm, rarely 7 in 5 mm proximally, and in 5 mm distally. Sicula cone-shaped, width at aperture moderately variable, some showing modest trumpet shape, dorsal wall straight or curved; apertures with fairly robust, straight or incurved dorsal processes (see Figs. 9.1, 9.2). Length and width of siculae mm and mm, respectively. REMARKS: This species has recently been described and illustrated both as flattened specimens on shale surfaces and threedimensionally. Some of the latter are illustrated as stereopairs in Lenz and Kozłowska-Dawidziuk (2004, pl. 28, figs ) of which two specimens are illustrated herein (see Figs. 9.1, 9.2). The images serve to illustrate the nature of the thecal hoods typical of the genus Uncinatograptus and of the sicular dorsal tongue, which is a common characteristic development in some Early Devonian species. U. birchensis differs from U. hercynicus in lacking the flaring trumpet-like sicula and in possessing a sicular dorsal tongue. From U. parangustidens, it differs in being more robust, widening relatively more rapidly, and being considerably wider. U. subhercynicus differs in being much narrower, essentially straight throughout its length, and its sicula is a simple, symmetrical cone. From U. angustidens Přibyl, 1940, it differs in its persistently dorsally curved proximal region. Uncinatograptus craigensis (Jaeger, in Churkin, Jaeger, and Eberlein 1970) Figures 10A.1 10A Monograptus craigensis Jaeger, in Churkin, Jaeger, and Eberlein, p. 198, fig. 6; figs. 7B, 7C, 8B, 8C, 9A, 9F, 9K Monograptus craigensis Jaeger in Churkin, Jaeger, and Eberlein 1970, Koren, p. 15, pl. 5, fig. 4; pl. 6, figs. 5, 6; pl. 7, figs. 7 12; [pars] pl. 10, figs. 5 13, [non] figs Monograptus craigensis Jaeger in Churkin, Jaeger, and Eberlein 1970, Porębska, p. 179, figs. 24/1 24/ a Monograptus craigensis Jaeger in Churkin, Jaeger, and Eberlein 1970, Lenz, p. 444, figs. C9 C13. COLLECTION SITES OF STUDY MATERIAL: Strathcona Fiord (SF93, m); Twilight Creek (TC88, collection #48); Humphries Hill (GSC localities C207194, m; C207195?, 1065 m); Polar Bear Pass, Bathurst Island (C207237, C207238); Moses Robinson River, Bathurst Island (C207019?, tentative identification). TYPE LOCALITY: Prince of Wales Island, southeastern Alaska. ARCTIC BIOSTRATIGRAPHIC RANGE: Pragian (and lower Emsian?), yukonensis Biozone. GLOBAL OCCURRENCE: Southeastern Alaska, Yukon Territory, Poland, Central Asia (Tadjikistan),?Yunnan (southern China). DESCRIPTION: Rhabdosome straight, following a moderate, but persistent, dorsal curvature (10 30 ) through the distance of the proximal three to four thecae. Width increasing moderately rapidly and smoothly from 0.7 to 1.03 mm including thecal hood and 0.44 to 0.7 mm excluding hood across theca 1; from 1.26 to 1.56 mm including hood and 0.89 to 1.25 mm excluding hood across theca 5, and from 1.78 to 1.9 mm including hood and 1.3 to 1.48 mm excluding hood distally. Thecae with generally robust and prominent hoods that decrease in size distally. Proximal thecal hoods generally robust and broad, often concealing thecal opening; distal thecal hoods shorter and narrower; thecae spaced in 5 mm proximally, and in 5 mm

12 1108 Can. J. Earth Sci. Vol. 50, 2013 distally. Interthecal septum sigmoidally curved, with long main portion, basal portion level with top of underlying theca. Sicula generally narrow cone that is often curved in a ventral direction; dorsal process very pronounced in some. REMARKS: Uncinatograptus craigensis stands midway between U. yukonensis and U. pacificus. It differs from the first species in having a proximally relatively short robust dorsally curved region that increases in width distally at a relatively uniform rate. It differs from the second species in possessing a more delicate proximal end with a more or less uniform curvature, whereas in the corresponding region of U. pacificus there is a fairly abrupt dorsal curvature through the distance of the sicula and the first two to three thecae, and width increases very rapidly in the same region (see Lenz 1988a). Uncinatograptus hercynicus (Perner, 1899) Figures 10B.1 10B Monograptus hercynicus Perner, p. 19, text-fig Monograptus hercynicus Perner, Jaeger, p. 87, pl. 1, figs. 1, 10; pl. 2, figs. 1 5; fig. pl. 3, fig. 1; text-figs. 15a 15b Monograptus hercynicus Perner, Teller, p. 331, figs. 1a 1i Monograptus hercynicus Perner, Hollard, and Willefert, p. 42, figs. a f Monograptus hercynicus hercynicus Perner, Jaeger, p. 184, pl. 16, figs. B, C Monograptus hercynicus Perner, Lenz and Jackson, p. 7, pl. 1, figs. 1 6; text-figs. 2A 2F Monograptus hercynicus Perner, Koren, figs. 5F 5H Monograptus hercynicus hercynicus Perner, Berry and Murphy, p. 51, pl. 1, fig Monograptus hercynicus Perner, Jaeger, text-fig. 2d; pl. 1, fig Monograptus aequabilis (Přibyl), Jaeger, table 1, fig Neomonograptus hercynicus (Perner), Wang, p. 202, pl. 2, figs. 3, a Monograptus hercynicus Perner, Koren, p. 119, pl. 1, figs. 7, 10; pl. 2, figs. 1, 2; text-figs. 4a 4g, 4l Monograptus hercynicus hercynicus Perner, Porębska, p. 162, figs. 20/1 20/ Neomonograptus hercynicus (Perner), Wang and Yao, p. 419, pl. 1, figs. 1 4; pl. 2, figs. 1, 10; text-figs. 3/1 3/ b Monograptus hercynicus hercynicus Perner, Lenz, p. 364, figs. 4A 4D Monograptus hercynicus Perner, Lenz et al., figs. 5.1, Monograptus hercynicus Perner, Zhang and Lenz, p. 358, figs , , , COLLECTION SITES OF STUDY MATERIAL: Grant Point (GP96, 171 and 173 m); Humphries Hill (HH94, 243 m); Twilight Creek (TC88, collections #39, #42, #43?); Cape Sir John Franklin (C198519). TYPE LOCALITY: Kosoř area, Czech Republic. ARCTIC BIOSTRATIGRAPHIC RANGE: Upper Lochkovian, hercynicus Biozone. GLOBAL OCCURRENCE: Yukon, Poland, Nevada, Yunnan (southern China), Germany (Thuringia), Pai-Khoi (northernmost Urals), Thailand, Central Asia, southern Spain, Czech Republic, Sardinia, Morocco. DESCRIPTION: Rhabdosome mostly straight, with modest dorsal curvature up to level of thecae 2 3, exaggerated by rapid distal widening of sicula. Thecae uniform, but prominence and thecal hood length lessening gradually distally; in some specimens, distal thecal hoods only slightly smaller and, in others, hoods considerably reduced distally. Interthecal septum strongly sigmoidal, main part inclined 30 45, basal portion noticeably distanced from underlying theca. Width increasing from 0.8 to 1.03 mm including thecal hoods and 0.6 to 0.8 mm without thecal hoods across theca 1; from 1.1 to 1.33 mm with hoods and 0.89 to 1.03 mm without hoods across theca 5; and from 1.55 to 2.07 mm with hoods and 1.22 to 2.3 mm without hoods distally. Thecal spacing 6.5 7, rarely 8, in 5 mm proximally and distally. Sicula flaring in a trumpet-like profile, mm long, apex level with top of theca 2, apertural width mm, apertural rim undulose, without dorsal process. REMARKS: This species is one of the more common and widespread Early Devonian graptolites globally. One of its main distinctive features is the possession of a sicula that flares into a trumpet shape, but it lacks the dorsal tongue. Of the species described in this paper, only U. falcarius, Neomonograptus bardoensis, and N. himalayensis (= N. atopus) share this feature. From the first species, U. hercynicus differs in having a much lesser dorsal curvature; from the second, it differs in possessing well-developed thecal hoods throughout; and from the third, it differs in its welldeveloped thecal hoods throughout. A few specimens might qualify as U. hercynicus nevadensis (Berry 1967), considering that their distal widths exceed 2.0 mm (see Fig. 10A.1, which is 2.3 mm), but these are rare. Uncinatograptus langgunensis (Jones, 1973) Figures 11B.1 11B Monograptus aff. yukonensis Jaeger and Stein in Jaeger et al., p. 180, pl. 15, figs. D F; text-fig. 1G 1I Monograptus yukonensis Jackson and Lenz, Lenz and Jackson, text-fig. 5G (non text-figs. 5A 5F) Monograptus langgunensis Jones, p. 23, pl. 1, figs. 5a 5c Monograptus n. sp. aff. yukonensis Jaeger and Stein (in Jaeger et al. 1969), Mu and Ni, text-fig. 3F Monograptus yukonensis fangensis Jaeger and Stein (in Jaeger et al. 1969), Wang, p. 200, pl. 1, figs ?1977 Monograptus aff. yukonensis Jaeger and Stein (in Jaeger et al. 1969), Wang, p. 200, pl. 1, figs. 1 4; pl. 3, figs. 3, 6, Monograptus langgunensis Jones, Jaeger, text-fig. 2R Monograptus yunnanensis Ni and Jiao, p. 305, pl. 3, figs. 1 4 [non fig. 5 = U. yukonensis]. 1988a Monograptus langgunensis Jones, Lenz, p. 446, text-figs. 6, A1 A4. COLLECTION SITES OF STUDY MATERIAL: Twilight Creek (TC88, collections #46, #48), Humphries Hill (HH94, 204? and 243 m), Polar Bear Pass (GSC collection C207236, 477 m). TYPE LOCALITY: Upper Detrital Member of the Setul Formation, Pulau Langgun, Langkawi Islands, Malaysia. ARCTIC BIOSTRATIGRAPHIC RANGE: Pragian (and lower Emsian?), yukonensis Biozone. GLOBAL OCCURRENCE: Yukon, southeastern Alaska, Yunnan (south China), Guangxi (southeast China), Xizang (Tibet), Thailand. DESCRIPTION: Rhabdosome dorsally curved throughout its length; proximal region up to the level of about the sixth theca strongly curved through 30 40, then more gently distally, but still curving in longest specimen with 22 thecae. Proximal end delicate, widening very gradually, but steadily, to about level of theca 7 or 8, much more gently distally; distal-most regions beyond thecae parallel sided. Thecal hoods moderately prominent proximally, becoming smaller distally to thecae 10 12, following which thecal apertures always visible. Interthecal septa proximal portion not reaching level of underlying septum. Width mm across theca 1 including hoods and mm excluding hoods; mm with hoods and mm without hoods across theca 5; and mm with hoods and mm distally. Thecae spaced in 5 mm proximally, distally. Sicula a thin cone, length (one complete sicula) 1.85 mm, width mm; with dorsally curved dorsal apertural tongue, apex reaching top of theca 2. REMARKS: This species is relatively uncommon in Arctic Canada, there being only about one dozen specimens, most not well preserved. Morphologically it is very close to Uncinatograptus yukonensis,