A New Species of Aneurophyton (Progymnospermopsida) from the Middle Devonian of West Junggar, Xinjiang, China, and Its Paleophytogeographical Significance

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A NEW SPECIES OF ANEUROPHYTON (PROGYMNOSPERMOPSIDA) FROM THE MIDDLE DEVONIAN OF WEST JUNGGAR, XINJIANG, CHINA, AND ITS PALEOPHYTOGEOGRAPHICAL SIGNIFICANCE

Qing Jiang,*,† Yi Wang,* Hong-He Xu,1,* and Jing Feng†

*State Key Laboratory of Paleobiology and Stratigraphy, Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, 210008 Nanjing, People’s Republic of China; and †University of Chinese Academy of Sciences, 100049 Beijing, People’s Republic of China

Aneurophyton doui sp. nov. (Aneurophytales, Progymnospermopsida) is described from the late Middle Devonian Hujiersite Formation of Hoxtolgay, Xinjiang, northwest China, as a plant with at least four orders of axes and ultimate units (vegetative appendages/fertile organs). Spines cover the surface of all orders of axes and ultimate units. The second-order axes and the vegetative appendages are closely inserted in pairs and helically arranged. From the second order, axes of subsequent orders are produced by bifurcation. The vegetative appendages are unwebbed and up to three times dichotomous. The fertile organ is pinnate, and the fertile organ axes are opposite or subopposite with adaxial, elliptical sporangia. This is the ﬁrst formal report of Aneurophyton beyond the coasts of the Rheic Ocean. West Junggar, the locality of present species of Aneurophyton, played a key role in the dispersal of Aneurophytales in the Middle Devonian.

Keywords: Aneurophyton, progymnosperm, Devonian, paleophytogeography, Xinjiang.

Introduction of Aneurophyton, and the paleophytogeographical significance and possible migration route of Aneurophytales are discussed. The Progymnospermopsida, being characterized by pterid- ophytic free-sporing reproduction but gymnospermous sec- ondary vascular tissues (Beck 1960; Bonamo 1975; Gensel and Material and Methods Andrews 1984; Hammond and Berry 2005), is subdivided into three orders: Aneurophytales, Archaeopteridales, and Protop- Twenty-three specimens were collected from a small quarry ityales (Kraüsel and Weyland 1941; Beck 1960; Beck and by National Highway G217, ∼20 km north of the town of Wight 1988). Among them, Aneurophytales is thought to be Hoxtolgay, Hobuksar Menggol Autonomous County, Xin- the most primitive (Kraüsel and Weyland 1941; Beck 1960; jiang, China (lat. 46Њ3655N, long. 86Њ0105E). The strata Hammond and Berry 2005). Genera in Aneurophytales estab- belong to the G217 Highway Section of the Upper Member lished on the basis of both morphological and anatomical char- of the Hujiersite Formation (for detailed introduction and fig- acters include Tetraxylopteris Beck 1957, Rellimia (Dawson) ures, see Xu et al. 2012a, forthcoming). Leclercq et Bonamo 1973, and Aneurophyton Kraüsel et Wey- Specimens are preserved as coalified compressions and im- land 1923. Triloboxylon Matten et Banks 1966 is mainly based pressions in yellow-green to gray tuffaceous siltstone. The on anatomy but also some morphological characters. Other plant fossil bed was dated to the late Mid-Devonian (Givetian) genera, such as Proteokalon Scheckler et Banks 1971, Rei- on the basis of palynology (Xu et al., forthcoming). Plants mannia Arnold 1935, and Cairoa Matten 1973, were estab- reported from the Hujiersite Formation include Lepidoden- lished on anatomical characters only (Scheckler 1975; Beck dropsis theodori Jongmans (Cai and Wang 1995), Tsaia conica and Wight 1988; Hammond and Berry 2005). Aneurophyta- Wang et al. (2004), Leclercqia cf. complexa Banks et al. (Xu lean rhizomes were recently described from Gilboa, although and Wang 2008), Leclercqia uncinata Xu et al. (2011), Has- no genus was designated (Stein et al. 2012). kinsia hastata Berry et Edwards, Haskinsia sagittata Edwards The diagnostic characters of Aneurophyton come mainly et Benedetto (Xu et al. 2008), Compsocradus givetianus from the type species, A. germanicum Kraüsel et Weyland (Wang) Fu et al. (2011), and Hoxtolgaya robusta Xu et al. 1923, widely reported from the Middle Devonian of Eur- (2012b). america (Serlin and Banks 1978; Schweitzer and Matten 1982). Sharp needles were used to remove the matrix embedding In this article, A. doui sp. nov. is described from the late Middle the plant fossils to obtain morphological information (de´gage- Devonian Hujiersite Formation of West Junggar, Xinjiang, ment; Fairon-Demaret et al. 1999). Macrophotographs were China. This locality is far away from the earlier occurrences taken using a Nikon D-100 camera with a Nikkor 105-mm macro lens; cross polarized illumination was used to enhance 1 Author for correspondence; e-mail: [email protected]. contrast. Microphotographs were taken using a Leica MZ-16 Manuscript received October 2012; revised manuscript received April 2013; stereomicroscope with annular ring illumination and a Leica electronically published September 4, 2013. D480 digital camera.

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This content downloaded from 119.78.212.207 on Sat, 21 Dec 2013 04:16:45 AM All use subject to JSTOR Terms and Conditions Fig. 1 Aneurophyton doui sp. nov. from the Middle Devonian Hujiersite Formation, Xinjiang, China. A, Holotype and paratype occur in one rock. Vegetative (left, holotype, PB21568) and fertile part (right, paratype, PB21569A) of the plant. Scale bar p 10 mm. B, Enlargement of the portion indicated by arrowhead 2 in A, showing four second-order axes inserted into the ﬁrst-order axis. Note that the lower pair (IIA1 and IIA2) extends opposite the observer; the upper pair (IIB1 and IIB2) extends toward the observer. IIA1 dichotomizes into two third-order axes p (III1 and III2). Scale bar 10 mm. C, Enlargement of the portion indicated by arrowhead 3 in A, showing bifurcation of a second-order axis. Spines are on both second-order and third-order axes (arrowheads). Scale bar p 5 mm. D, Enlargement of the portion indicated by arrowhead 1inA, showing spines (arrowheads) and longitudinal coal-ﬁlled depression on the surface of the axis. Scale bar p 5 mm. E, F,Partand counterpart. Two isolated terminal axes with vegetative appendages and detached sporangia at the distal part. Scale bar p 10 mm. PB21570. G, Enlargement of the portion indicated by the black arrowhead in F, showing tongue-shaped depressions (arrowheads) at the basal part of vegetative appendages indicating embedded appendages in one pair. Scale bar p 2 mm. H, Arrowed axis in F, after preparation. Note that the paired vegetative appendages are helically attached. Scale bar p 10 mm.

This content downloaded from 119.78.212.207 on Sat, 21 Dec 2013 04:16:45 AM All use subject to JSTOR Terms and Conditions Fig. 2 Aneurophyton doui sp. nov. from the Middle Devonian Hujiersite Formation, Xinjiang, China. A, B, Part and counterpart. Note the four orders of axes (I–IV) and vegetative appendages attached to the fourth-order axes. Scale bar p 10 mm. PB21571. C, First-order axis in B, before preparation. The tongue-shaped depression (black arrowhead) indicates the attachment of another second-order axis. Scale bar p 10 mm. D, Enlargement of the third- and fourth-order axes in A, after preparation. Paired vegetative appendages are attached helically to the fourth-order axes. Scale bar p 10 mm. E, Enlargement of a pair of vegetative appendages (black arrowhead in D), showing the paired appendages dichotomizing three times into the ﬂattened segments. The ﬁrst dichotomy of the complete appendage results in the left branchlet (black arrowhead) and the right branchlet (white arrowhead). Note that the left branchlet leans into matrix, the right parallel to the slab surface. Scale bar p 5 mm. F, Enlargement of a portion of the fourth-order axis IV4 (white arrowhead in A), showing the decurrent bases of vegetative appendages and the spines (white arrowheads) on the axis. Scale bar p 5 mm. G, Enlargement of the distal portion of axis III in A, showing the third-order axis dichotomizing into two fourth-order axes. Spines are on both orders (white arrowheads). Tongue-shaped depressions are seen at the basal part of the vegetative appendage p (black arrowhead). Scale bar 5 mm. H, Enlargement of a portion of axis IV4 (black arrowhead in A). Spines are at the base of the sterile unit (white arrowheads). Tongue-shaped depressions indicate the embedded vegetative appendages (black arrowheads). Scale bar p 2mm.

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Systematic Paleobotany

Class—Progymnospermopsida Beck 1960

Order—Aneurophytales Kra¨ usel et Weyland 1941 emend. Beck 1960

Family—Aneurophytaceae Kra¨usel et Weyland 1941

Genus—Aneurophyton Kra¨usel et Weyland 1923 emend. Schweitzer et Matten 1982

Type Species—Aneurophyton germanicum Kra¨usel et Weyland 1923 emend. Schweitzer et Matten 1982

Species—Aneurophyton doui Jiang, Wang, Xu et Feng sp. nov. Diagnosis. At least four orders of axes and ultimate units (vegetative appendages/fertile organs) are known. Spines, 0.5– 1.5 mm long, occur sparsely on the surface of all orders of axes and ultimate units. First-order axes, up to 6 mm wide and at least 90 mm long, demonstrate only a slight distal taper. Second-order axes, up to 4 mm wide, diverge helically from the first-order axis in closely inserted pairs. From the second order, axes of subsequent orders are produced by bifurcation; third-order axes are 2.0–2.5 mm wide, and fourth-order axes are 1.5–2.0 mm wide. Vegetative appendages, 7.0–13.0 mm long as a whole, diverge from the third- or fourth-order axes in helical pairs, as a one to three times dichotomizing system of three-dimensionally-extended flattened branchlets. Fertile organs, 3.7–8.0 mm long as a whole and borne on the third- or fourth-order axes, are up to three times opposite/subopposite pinnate systems. All three orders of fertile organ axes, in most cases recurved and rarely straight, bear sporangia or organ axes. Sporangia, oppositely, suboppositely, or alternately, are inserted distichously to the usually adaxial side of Fig. 3 Line drawing of spines on the axes and ultimate units (in- the fertile organ axes; they are short-stalked, elliptical, 0.8– cluding vegetative appendages and fertile organs). A–C, From the veg- 1.3 mm wide, and 2.2–3.5 mm long, and they sometimes have etative first-order axis (arrowheads in fig. 1D). D, From the vegetative longitudinal dehiscence or a twisting configuration. second-order axis (the lowermost arrowhead in fig. 1C). E–I, From the vegetative third-order axis (the two upper arrowheads in fig. 1C,the Holotype. PB21568 (fig. 1A). three lower white arrowheads in fig. 2G). J–O, From the vegetative Repository. Nanjing Institute of Geology and Paleontol- fourth-order axis (arrowheads in fig. 2F; top white arrowhead in fig. ogy, Chinese Academy of Sciences. 2G). P–R, From the fertile second-order axis (arrowheads in fig. 10A, Locality. A small quarry by National Highway G217, ∼20 the left arrowhead in fig. 10C). S, T, From the fertile third-order axis km north of the town of Hoxtolgay, Hobuksar Menggol Au- (the right arrowheads in fig. 10C). U, V, From the basal part of a tonomous County, Xinjing, China (lat. 46Њ3655N, long. vegetative appendage (white arrowheads in fig. 2H). W, From the fertile 86Њ0105E). organ (arrowhead) in fig. 12B. Horizon. Upper Member of the Hujiersite Formation (Givetian, late Mid-Devonian). units are differentiated into vegetative appendages in pairs and Derivation. From the surname of Mr. Dou Ya-Wei, who pinnate fertile organs with recurved axes. We here use roman first illustrated Aneurophyton from Xinjiang Devonian (Dou numbers I–IV to refer to four orders of axes, capital letters A– 1983) and contributed a great deal to Xinjiang Paleozoic D and so on for a sequence of helically inserted axes, and sub- geology. script numbers 1 and 2 for paired axes or ultimate units inserted at the same point (figs. 1A,4A). P1, P2, and P3 represent the different orders of axes in the fertile organ, with subsequent Description capital letters (e.g., P2A, P2B) used to indicate the sequence; sporangia are marked with the letter s (figs. 12–15). The description is based on nine specimens selected from our collection. The plant is recognized as having at least four orders Spines of axes, with the last two orders (in most cases, the third and Spines are sparsely arranged but easily recognized on the sur- fourth orders) bearing ultimate units (figs. 1A,4A). The ultimate face of all orders of axes and ultimate units (fig. 3). Spines,

This content downloaded from 119.78.212.207 on Sat, 21 Dec 2013 04:16:45 AM All use subject to JSTOR Terms and Conditions Fig. 4 Line drawing of the vegetative branching system, based on specimens illustrated in ﬁgs. 1A and 2B. A, Four orders of vegetative axes (I–IV). Axis I bears four pairs of axes II (IIA–IID; subscript numbers 1 and 2 are for paired equivalents), and the following orders of axes give rise to subsequent orders by bifurcation. Vegetative appendages are helically attached to axis III (A–I in III1) or axis IV (vegetative appendages in IV1 and IV2). Spines cover the surface of all axes. B, The paired second-order axes are inserted on the ﬁrst-order axis.

Fig. 5 Line drawing of the third- and fourth-order axes in ﬁg. 2A,2B, and 2D. Dashed lines indicate positions of vegetative appendages previously buried in the matrix; dotted lines indicate continuation of vegetative portions that were not preserved. A, Axis III dichotomizes into two fourth- order axes (IV1,IV2). Two isolated fourth-order axes (IV3,IV4) overlap each other. Paired vegetative appendages with decurrent bases are helically attached to the fourth-order axes at regular intervals (A–F in IV2, A–I in IV4). B, Counterpart of A. Note that the distal portion of IV2 bears four vegetative appendages (H–K) that are absent in A.

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Fig. 6 Aneurophyton doui sp. nov. from the Middle Devonian Hujiersite Formation, Xinjiang, China. The third-order axis (III) gives rise to the fourth- and fifth-order axes (IV, V) and vegetative appendages (A–K). The vegetative appendages are particularly slender. PB21572. A, B, Two stages of serial de´gagement to the axis. Scale bar p 10 mm. C, Line drawing from A and B. Dashed lines indicate positions of sterile units previously beneath the matrix; dotted lines indicate continuation of sterile portions that were not preserved. nearly identical, range from 0.5 to 1.5 mm long, have a wide in pairs. Usually one second-order axis and a tongue-shaped base up to 0.7–0.9 mm in width, and taper to sharp points after depression (fig. 2C, arrowhead) are initially visible. Another constricting abruptly into straight needles 0.2 mm wide (white second-order axis is uncovered beneath the tongue-shaped de- arrowheads in figs. 1C,1D,2F–2H,10A,10C,12B). Spines pression (fig. 2B). These two axes share the same attachment are usually attached perpendicularly to the surface of axes (fig. point, form a V-shaped structure, and compose a trichotomy 3B,3E,3N,3R,3W), except some deflected ones (fig. 3C,3O, along with the first-order axis (figs. 2B,4B). 3Q). Spines on the first-order axis (fig. 3A–3C) are longer and In our largest slab, four pairs of second-order axes (IIA–IID) more rigid than those on the other axes (fig. 3D–3X). Spines are helically arranged along the first-order axis (figs. 1A,4A). on the ultimate units are usually attached to the basal part of The longitudinal distance between the insertion of pairs of sec- a vegetative appendage (fig. 2H, white arrowheads) or to the ond-order axes ranges from 12.8 to 30.4 mm. From this spec- basal portion of the P1 axis in a fertile organ (fig. 12B, imen, we see that pair IIA is under axis I: axis IIA is overlapped arrowhead). 1 by axis I, while IIA2 departs laterally from the axis I at an angle of 50Њ but extends downward into the matrix with its bifurcated Vegetative Branching System terminal portion (fig. 1A,1B). IIB is attached to the upper surface

First-order axes (I). The longest first-order axis is at least of axis I, with IIB1 preserved as a short base and IIB2 bent 95 mm long, with both ends missing and both sides straight downward (fig. 1A,1B). To the right side of axis I arise pair (figs. 2B,2C,4B). The axes of this order range from 3.5 to IIC, in which IIC1 has an identifiable dichotomy below axis I 6.0 mm in width; no obvious tapering is seen (figs. 1A,2B). and IIC2 has a splintered base overlapping. IID arises from the A longitudinal coal-filled depression, suggesting a ribbed stem upper surface of the first-order axis on the left side. or xylem structure, is occasionally present (fig. 1D). Second-order axes (II). The second-order axes are 3.6– The second-order axes diverge helically from the first order 4.0 mm wide and 20–50 mm long (fig. 1A), each dichotomized

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Fig. 7 Line drawings of a vegetative axis and its vegetative appendages. Part (A, B, sketched after the right isolated axis in fig. 1F and 1H) and counterpart (C, sketched after the left isolated axis in fig. 1E). A, Before preparation. Tongue-shaped depressions are present at the base of each vegetative appendage. B, After preparation. Up to nine pairs of vegetative appendages (A–I, with the exception of G and I as single ones) with decurrent bases are helically attached to the axis at regular intervals. Dotted lines indicate the de´gaged portions. C, Counterpart of A. Vegetative appendages C1 –I are equivalent to C1–I in A. into two equal third-order axes at angles of 50Њ–60Њ (fig. 1A, recognized in the present plant. The fifth-order axes arise from 1C). The distance between the base of the second-order axis the fourth-order by bifurcation. The width of the two orders and the bifurcation point varies (figs. 1A,4A): in the largest has no apparent difference, ranging from 2.0 mm at the base slab (fig. 1A), axis IIA2 is 19.7 mm long and axis IIB2 is 36.9 to 1.5 mm in the distal portion (IV and V, fig. 6). The axes of mm long, while in another slab (fig. 2B), where the bifurcation these two orders helically bear the vegetative appendages, point is missing, two second-order axes stretch for 20.8 and which are spaced at intervals of 3.0–10.0 mm. 50.1 mm, respectively. ∼ Third-order axes (III). Third-order axes are 2.5 mm in Vegetative Appendages width; where branched they dichotomize into fourth-order Њ Њ axes at an angle of 30 –50 (III2 in fig. 4A; III in figs. 2A,6) The vegetative appendages are inserted on the final two or are undivided. In one example (fig. 1A), the distally bifur- orders of axes in pairs (fig. 1A,1H; fig. 2A,2D, IV; fig. 5; cated third-order axis is only 15 mm long (III2 in fig. 4A), fig. 6, IV and V). This paired pattern is usually hidden before while the stretched third-order axis (III1) is at least 65 mm long preparation, but tongue-shaped depressions on the axis and bears spirally arranged vegetative appendages. Specimens clearly indicate the embedded appendages (fig. 1G, arrow- of third-order axes are abundant. Some isolated fourth-order heads; fig. 2G, black arrowhead; fig. 2H, black arrowheads; axes probably belong to the distal dichotomies of the same fig. 7A). third-order axis (IV3 and IV4; figs. 2A,2D, 5). Vegetative appendages are usually 7.0–13.0 mm long, up

Fourth- and fifth-order axes (IV and V). Another two to three times dichotomous, and unwebbed (fig. 2E;D1 and orders of axes, IV (figs. 2A,2D,4A, 6) and V (fig. 6), are D1 in fig. 7C). De´gagement reveals that two vegetative ap-

This content downloaded from 119.78.212.207 on Sat, 21 Dec 2013 04:16:45 AM All use subject to JSTOR Terms and Conditions Fig. 8 Aneurophyton doui sp. nov. from the Middle Devonian Hujiersite Formation, Xinjiang, China. A, Enlargement of the fertile part in ﬁg. 1A with three orders of axes and fertile organs (e.g., arrowheads 1–3). Scale bar p 10 mm. PB21569A. B, Counterpart of the middle portion of the fertile branching system illustrated in A. Arrowhead 1 indicates a simple fertile organ with only one order of organ axis; arrowhead 2 shows the counterpart of the fertile organ indicated by arrowhead 2 in A. The black arrowhead shows that the third-order fertile axis gives rise to the fourth orders by bifurcation. Scale bar p 10 mm. PB21569B. C, An isolated recurved fertile organ axis. Arrowheads indicate the alternately arranged sporangia. Scale bar p 2 mm. PB21573. D, Enlargement of the portion indicated by the black arrowhead in A, showing the fertile units attached to the axis. Scale bar p 2 mm. E, Enlargement of the portion indicated by arrowhead 1 in A. Scale bar p 2 mm. PB21636A. F, Counterpart of the specimen in E. The black arrowhead indicates a sporangium with twisted conﬁguration. Scale bar p 2 mm. PB21636B. G, A fertile organ with two orders of suboppositely arranged fertile axes. Scale bar p 2 mm. PB21574.

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Fig. 9 Line drawing of the fertile branching system, based on specimens in ﬁg. 8A,8B, and 8F. Three orders of axes (II, III, IV) and 10 fertile organs are observed. The fertile organs are either simple, formed by one order of fertile organ axis (foA–B, foE, foH), or complex, consisting of at least two orders of axes (foC–D, foF–G, foI–J).

pendages from the same attachment point form a V-shaped 7B). Vegetative appendages B1 and B2 extend laterally. Similar divergence from the main axis (fig. 1H; fig. 2D, arrowhead; preparation of the other vegetative appendages (fig. 7B,7C) figs. 2E,5A; fig. 6A,6B,6I,6J), each with a decurrent base revealed a helical pattern of insertion of axes. (figs. 1G,1H,2D,7A,7B) and departing from the main axis Some vegetative appendages are especially slender and flex- at angles of 40Њ–70Њ. The basal axis of a vegetative appendage ible, with elongate bases decurrent to the axis. The distance ranges from 0.8 to 1.3 mm in width and distally bifurcates before its first bifurcation point is relatively long (e.g., vege- Њ Њ up to three times at angles of 50 –70 , forming several flat- tative appendages B1,I1, and K in fig. 6). The length of these tened segments each 0.3–0.6 mm wide with a rounded, out- slender vegetative appendages is at least 10 mm and is some- wardly curved tip. The distalmost segments are arranged times up to 16 mm (see I1 in fig. 6). three dimensionally. One typical vegetative appendage (fig. 2E) dichotomizes three times, and the angles of these di- Reproductive Branching System chotomies are in the range of 50Њ–70Њ. The first dichotomy results in a left branchlet (black arrowhead), which further The reproductive portion of the plant consists of three orders bifurcates twice with its left side going into the matrix, and of axes (II–IV) and fertile organs. The third-order axes arise a right branchlet (white arrowhead) nearly parallel to the from the second-order axis, sometimes in pairs. They produce slab surface. fourth-order axes by bifurcation. The arrangement of vegetative appendages on an axis was Second-order axes (II). The longest second-order axis is revealed by de´gagement (figs. 5, 7). In a well-preserved spec- 16.8 mm long, with both ends missing (fig. 8A; II in fig. 9A). imen, nine pairs of vegetative appendages were observed (figs. The portion of the second-order axis before giving rise to the

1F,1H, 7). Vegetative appendages A1 and A2 extend slightly third-order axes is at least 15 mm long (fig. 10A–10D; II and downward into the matrix. B1 overlaps B2, leaving B2 merely II in fig. 11). The width of second-order axis ranges from 3.3 a tongue-shaped depression (fig. 7A) before preparation. After to 3.5 mm proximally and from 2.4 to 2.7 mm distally. The removing the basal portion of B1, a part of B2 appeared (fig. third-order axes, in pairs (fig. 10B, black arrowhead; fig. 10D,

This content downloaded from 119.78.212.207 on Sat, 21 Dec 2013 04:16:45 AM All use subject to JSTOR Terms and Conditions Fig. 10 Aneurophyton doui sp. nov. from the Middle Devonian Hujiersite Formation, Xinjiang, China. A–D, Fertile axes with paired third- order axes (black arrowheads), possible vegetative appendages (A–E, A–E), fertile organs (foA–foC), and spines (white arrowheads in A and C). A and B illustrate the same specimens, with serial de´gagement. PB21575A. C and D illustrate the counterpart, with serial de´gagement. PB21575B. Scale bar p 10 mm. E, Enlargement of the portion indicated by the white arrowhead in D, showing the arrangement of sporangia. Scale bar p 1 mm. F, Enlargement of foC (white arrowhead in B), showing that the organ contains in total two fertile organ axes to which the sporangia are attached adaxially, after removing the overlapped third-order fertile axis. Scale bar p 2 mm. G, Enlargement of the fertile portion indicated by the black arrowhead in ﬁg. 1E. Clusters of sporangia are recognized as fertile organ with two orders (upper arrowhead) or one order (middle and lower arrowheads). Note that six sporangia (lower arrowhead) are distichously and alternately arranged along the organ axis. Scale bar p 5 mm. H, Enlargement of the portion indicated by the upper arrowhead in G, showing two orders of organ axes, with only two sporangia attached. Scale bar p 1 mm. I, Enlargement of the fertile portion indicated by the white arrowhead in ﬁg. 1E, showing the fertile arms (white arrowheads). Note the two sporangia with longitudinal dehiscence (black arrowhead). Scale bar p 2mm.

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Fig. 11 Line drawing of the branching system with fertile units, based on specimens in ﬁg. 10A–10D. The third-order axes are attached to the second-order axis either in pairs (IIIA1 and IIIA2, IIIB1 and IIIB2) or singly (IIIC). Note that a third-order axis (IIIB 1) bifurcates three times. Fertile organs (foA–C) and some incomplete ultimate units (A–E, A–E) are borne on the third-order axis.

black arrowhead; IIIB1 and IIIB2 in fig. 11A; IIIA 1 and IIIA 2 occasionally up to 8.9 mm long (fig. 8A, arrowhead 2; fig. in fig. 11B) or singly (IIIC and IIIC in fig. 11), diverge from 13), and 2.3–11.2 mm wide, consisting of up to three times the second-order at the angle of 40Њ–50Њ. pinnate organ axes (P1, P2, and P3 in figs. 12–14) bearing Third- and fourth-order axes (III and IV). Third-order elliptical sporangia. The distinct structure of the fertile organ axes are 2.0–2.3 mm wide basally and taper to 1.0 mm at the is illustrated by schematic architectural models (fig. 15). distal end, and they are up to 36 mm in length (fig. 10C; IIIA 1 A pinnate organ axis can bear sporangia, the higher order in fig. 11B). They either further bifurcate into subsequent axes of axis, or both (fig. 15E). First-order pinnate organ axes (P1) (fig. 8B, black arrowhead; IIIA in fig. 9B; IIIB 1 in fig. 11B) are attached to the ultimate fertile axes; they either bear spo- or bear fertile organs directly (fig. 8A,8B; fig. 9, foA–F and rangia at one (usually the adaxial) side (fig. 8B, arrowhead 1; foH; fig. 10B,10D, white arrowheads; fig. 11, foA–C). foE in fig. 14A; fig. 10G, middle and lower arrowheads; fig. Fourth-order axes are not always present in a reproductive 10I, white arrowheads) or give rise to second-order organ axes branching system. They are up to 1.0 mm wide, similar to the oppositely or suboppositely (figs. 8G, 12, 13, 14B), forming distal width of the third-order axis (fig. 9, IV1 and IV2). Some simple or complex fertile organs. In some circumstances, P1 incomplete organs arising from the third-order axis (fig. 11A, bear sporangia distally and P2s proximally (figs. 8G,14B). 11B, A–E) are probably ultimate units. Though incompletely P2s also bear both the sporangia (fig. 10B, white arrowhead; preserved, the dichotomized organs C and D (fig. 11A) 1 2 fig. 12, P2A–P2D; fig. 13, P2A–P2C) and P3s (fig. 13D,13D , strongly resemble the vegetative appendages, and the pairs C 1 P2D). P1s are 0.5–1.2 mm wide and 2.3–13.0 mm long; P2s and C and D and D , together with A, B, and distal E, are 2 1 2 are narrower, with a width of 0.4–0.8 mm (hardly exceeding reminiscent of helically arranged appendages along the third- 1.0 mm) and a length of 1.6–7.3 mm (figs. 8C,10F,14E); P3s order axis. and sporangia can be borne on the same P2 axis (fig. 13C, 13D,13C,13D). Fertile Organs (fo) and Pinnate Organ Axes (P) Thus, the specimen illustrated in figures 8G and 14B typifies A fertile organ (fo) is a distinct ultimate unit attached to a fertile organ of Aneurophyton doui. It demonstrates two fertile axes of the distal two orders (fig. 8A,8B; foA–I in fig. orders of pinnate organ axis. P1 bears at least four P2s, which 9; foA–C in figs. 10A and 11). An individual fertile organ is are arranged oppositely and pinnately. The sporangia are at- 3.7–8.0 mm long from the base to the preserved distal part, tached to the distal part of both P1 and every P2 (fig. 14B).

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are obvious (figs. 8C,14E), according to the pattern of par- tially embedded sporangia (fig. 8C, arrowheads 1 and 3) and those with intact outlines (fig. 8C, arrowheads 2 and 4). Some fertile organ axes compressed from the adaxial side show the alternate distichous arrangement of sporangia (fig. 10G, lower arrowhead), where at least six sporangia are present. A few sporangia are arranged as if they were in pairs (figs. 8G,14B,

s1 and s2;10E,14C,s1 and s2,s3 and s4), suggesting an opposite or subopposite pattern. Sporangium number in one organ axis

varies from 1 (fig. 14D,s1 in P2) to 8 (fig. 14E). So, with four or more P2 axes, the total number of sporangia can exceed 32 (see fig. 15E), although a fertile organ preserving 12 sporangia provides the largest number in our specimen (fig. 13). Excepting a few sporangia with acute tips (fig. 10H) probably due to preservation, the sporangia have rounded tips, are short-stalked and elliptical in outline, are 0.8–1.3 mm wide and 2.2–3.5 mm long as a whole, and dehisce longitudinally (fig. 10I, black arrowhead; fig. 13B, arrowhead; fig. 13B ,s7). Plump sporangia with a larger width usually have straight or convex sides (figs. 8C,10E), while slim, shrunken ones tend to twist (fig. 8F, arrowhead).

Discussion

Although no anatomical information is known, the new plant, with three-dimensional branching, unwebbed dichotomous vegetative appendages, and a pinnate fertile system with recurved axes, is obviously a member of the aneurophytes. It is furthermore attributed to Aneurophyton doui sp. nov. be- cause of the recurved organ axes with distichous sporangia and the elliptical, sparsely attached sporangia. This is the first formal report of Aneurophyton from the Devonian of Xinjiang. Dou (1983) illustrated four unprepared specimens of Aneu- rophyton aff. germanicum from Tuoli, northwest Xinjiang, ∼200 km west of our locality. In his description, the plant is composed of a stem and attached “fronds” up to three orders; small spines cover the proximal part of the ultimate and pen- Fig. 12 A, B, Two stages of serial de´gagement to the fertile organ ultimate pinnae, dichotomous leaflike organs are alternately indicated by arrowhead 3 in fig. 8A. A, Complex fertile organ consisting attached to the ultimate pinna, and paired or clustered spo- of two orders of fertile organ axis. B, Exposure of embedded fertile arms. rangia are elliptical and stalked. However, few authors have Note the spine (arrowhead). A, B, Line drawing of the two stages of serial de´gagement, showing a pinnate system consisting of a first-order cited Dou’s (1983) work. His original specimens were lost, axis (P1), four oppositely arranged second-order axes (P2A and P2B, and it is impossible to make further comparisons with the

P2C and P2D), and nine sporangia (s1–s9). present plant from the illustrations only.

Comparison with Species of Aneurophyton In addition, some fertile organs have up to three orders of organ axis (fig. 13). Those are combined into a complex sce- The type species of Aneurophyton, A. germanicum, has been nario of a single fertile organ (fig. 15E). Other fertile organs reported from Wuppertal, Germany (Kraüsel and Weyland with P2s are simpler (figs. 10F, 12, 15C,15D); the opposite 1923, 1926, 1929; Schweitzer and Matten 1982), and New arrangement is a strong resemblance to the dichotomizing pat- York, United States (Serlin and Banks 1978). The fertile organ tern, particularly when only two P2s are attached to P1 (figs. of the species is characteristic and was described as a lyre- 10F,15C). In most cases, a fertile organ consists of only one shaped structure with a central stalk and two recurved arms, order of axis (see fig. 15A,15B, corresponding to fig. 8B, with short-stalked oblong-elliptical sporangia borne “in a stag- arrowhead 1; foE in fig. 14A; fig. 10G, middle and lower gered, two-rowed arrangement” (Serlin and Banks 1978). arrowheads; fig. 10I, white arrowheads). Schweitzer and Matten (1982) agreed with that configuration Sporangia. Sporangia are alternately, suboppositely, or and drew a reconstruction of the “sporangiophore” (equiva- oppositely arranged in two ranks, attached adaxially to the lent to “fertile organ” in this article; text fig. 2 in Schweitzer usually recurved organ axes (fig. 14A–14F). In some laterally and Matten 1982). compressed specimens, the alternate arrangement of sporangia This lyre-shaped pattern can be traced in the present spec-

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Fig. 13 Serial de´gagements of the fertile organ indicated by arrowhead 2 in fig. 8A. A–D, Four stages of the de´gagement, exhibiting one P1 axis, oppositely arranged P2 axes (P2A and P2B, P2C and P2D), and two incomplete P3 axes. The white arrowhead in B indicates a sporangium with longitudinal dehiscence. E, Counterpart of the specimen shown in A–D. Scale bar p 2 mm. A–E, Line drawings of A–E. Note the recurved P2 axes (P2A, P2C) in A, which form a false lyre-shaped structure. imens (fig. 10B, white arrowhead; 10F). The recurved lyres The attachment of the second-order axes and ultimate units correspond to the recurved organ axes, and the sporangia are is helical in A. doui from Xinjiang. This is the same as in A. arranged in two ranks either in A. germanicum or in the pres- gemanicum. The paired pattern of axes resembles the “trifur- ent species. In fact, specimens of A. germanicum exhibit more cation” in A. germanicum from Germany (p. 68, 73, specimen variability in the morphology of fertile organ: some represent D, pl. 3, fig. 15, text fig. 7 in Schweitzer and Matten 1982). a two to three times dichotomous system resulting in more Dichotomous branching in the higher orders of axes (e.g., fig. than two lyre-shaped structures (German specimens: P. Giesen, 1A, arrowhead 3) is identical to that in the US plant, in which personal communication; Belgian specimens: N. Momont, per- “all higher orders of sterile branch may bifurcate” (p. 347, pl. sonal communication); some consist of “an undivided elon- 37, fig. 4, arrowhead d; pl. 37, fig. 5 in Serlin and Banks 1978). gated sporangiophore stalk terminated by a single lyre-shaped, The vegetative appendages of the new species are unwebbed fertile region” (Schweitzer and Matten 1982, p. 73). Thus, the three-dimensional systems up to three times dichotomous. occurrence of the recurved organ axis with distichously ar- These structures, including their size, the width of the seg- ranged elliptical sporangia is crucial to identify the genus. The ments, and outwardly curved tips, bear strong resemblance to lyre-shaped structure of the fertile organ, which was thought those of the type species. Some long and slender appendages to be a diagnostic character of the genus, might only have a (fig. 6, B1, I1, and K) are similar to the “sterile units near the feature of specific value. In general, A. doui and A. germanicum branch tips” in German A. germanicum (Schweitzer and share the recurved organ axes as the genus character, while Matten 1982, p. 73, specimen C, pl. 2, figs. 13 and 14, text the arrangement of these axes (pinnately in A. doui and di- fig. 6) or the terminal structures of branches in the US plant chotomously in A. germanicum) separates them into different (pl. 37, fig. 4, arrow p in Serlin and Banks 1978). species. In addition, in Xinjiang specimens, a few sporangia The other principal differences between the new species and are arranged as if they were in pairs (figs. 10E,14C,s1 and A. germanicum are the spines and paired versus single insertion s2,s3 and s4), which we interpret as an oppositely distichous of vegetative appendages. Spines, which cover the surface of pattern. Such a pattern seems to appear in the type species: the plant, may play a crucial role in adaptation to the envi- according to Giesen (personal communication, 2012), pairs of ronment for the early plants. The axes and ultimate units of sporangia sometimes occur in the proximal section of the spo- A. germanicum have no spines or circular scars that indicate rangiophore (fertile organ axis). More similarities occur in the snapped spines (Schweitzer and Giesen 2002); this glabrous sporangia, both of which are short-stalked and elliptical and surface contrasts with the spiny specimens from Xinjiang. For dehisce longitudinally. It is clear that further work needs to be vegetative appendages, two share one insertion point in the done on A. germanicum from the type area to clarify variation Xinjiang specimens, while only one appendage arises from one in sporangiophore morphology. insertion in A. germanicum. In addition, the organization of

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as a lyre-shaped dichotomous system in A. germanicum (fig. 15D). The sporangium of A. doui is larger (0.8–1.3 mm wide and 2.2–3.5 mm long) than that of A. germanicum (0.5–0.8 mm wide and 1.2–2.5 mm long; Serlin and Banks 1978; Schweitzer and Matten 1982). Aneurophyton germanicum var. pubescens, from the type locality of A. germanicum, was described as bearing little difference from the type species except for the spines (Schweitzer and Giesen 2002). The spines in this variety are up to 5 mm longer than those in the Xinjiang species but snapped easily, conforming to the deflected spines in A. doui. However, these spines occur only in the vegetative branching system of the variety (P. Giesen, personal communication, 2012), while in Xinjiang specimens the spines cover the surface of both vegetative and fertile axes and even the ultimate units. The paired pattern of vegetative appendages of the Xinjiang species is reminiscent of “Aneurophyton” maroccanum from central Morocco (Prestianni et al. 2012), the appendages of which are “up to 12 mm long and dichotomize isotomously three to four times” and “the first dichotomy occurs at, or very close to, the level of divergence from the axis” (Prestianni et al. 2012), as well as the Xinjiang species.

Comparison with Species of Rellimia Rellimia is reported from a large number of Middle De- vonian localities in western Europe, the United States, and central Morocco (Gerrienne et al. 2010). It contains only one valid species, R. thomsonii Leclercq et Bonamo 1973, and an indeterminate species from Morocco; both have a large fertile organ (30–40 mm long and 10–20 mm wide; Schweit- zer and Matten 1982; Gerrienne et al. 2010), dwarfing those in Aneurophyton doui (3.7–8.0 mm long and 2.3–11.2 mm wide). The fertile organ of A. doui is a pinnate system of up to three orders in which the second-order axes are opposite or subopposite along the first order; the sporangia are alternately or suboppositely attached to the adaxial arm in two rows. The fertile organ of R. thomsonii is more complex: it bifurcates once and then gives rise to pinnae up to four times (Kraüsel Fig. 14 Line drawing of the fertile organs and organ axis of and Weyland 1933; Leclercq and Bonamo 1971; Bonamo Aneurophyton doui sp. nov. A, A portion of the third-order fertile 1977; Gerrienne et al. 2010); the pinnae of lower orders are axis indicated by arrowhead 1 in fig. 8B, with three fertile units disposed in two rows in a pinnate arrangement (Leclercq and attached (foE, foF, foH). Both foE and foH have only one order of Bonamo 1971; Schweitzer and Matten 1982), as in A. doui. fertile arm (EP1, HP1), while foF has two orders. B, An isolated In fact, the fertile organ of A. doui looks like a single first- fertile organ in fig. 8G. Note the two orders of fertile arm. Both order pinna of that of R. thomsonii. sporangia (s –s ) and P2 axes are attached directly to P1. P2s are 7 10 The longitudinal dark line in the sporangium of R. thom- arranged suboppositely. C, A P2 axis in a fertile organ (fig. 10E), four sporangia arranged distichously and oppositely. The stubbed sonii (Leclercq and Bonamo 1971) and the longitudinal suture portion (?s) at the proximal part of P2 is probably a sporangium or in the present plant suggest the same dehiscence mechanism, even another P2. D, A fertile organ consisting of two orders of fertile but the shape and number of sporangia are different. In R. axis (fig. 10H). Three sporangia are observed, attached to both P2 thomsonii, there are more than 400 linear sporangia with

(s1) and P1 (s2,s3). E, An isolated fertile organ axis (perhaps P2 short, apiculate tips densely arranged in a fertile organ (Le- according to its width) drawn from ﬁg. 8C. The axis bears eight clercq and Bonamo 1971; Schweitzer and Matten 1982); in sporangia, which are arranged alternately or suboppositely. contrast, sporangia of A. doui are sparsely arranged with usually blunt tips, 10–40 in number. the fertile organs of both species are different: in the type The vegetative branching system of R. thomsonii and that species, those organ axes (or lyres, fertile arms) tend to com- of the present plant are similar; the former has up to ﬁve orders pose themselves in a dichotomous way; in A. doui,theyor- of axes and ultimate units borne in helical sequences (Leclercq ganize themselves pinnately. However, it should be noted that and Bonamo 1971; Schweitzer and Matten 1982; Dannen- a pinnate fertile organ consisting of only two axes appearing hoffer and Bonamo 2003; Dannenhoffer et al. 2007), which

This content downloaded from 119.78.212.207 on Sat, 21 Dec 2013 04:16:45 AM All use subject to JSTOR Terms and Conditions ; from A. ger- üsel and Kra Aneurophyton A. germanicum . The designation of ; studied by Krishtofovich, a s and studied the associated for further comparisons. zer and Giesen (2002) restudied it Aneurophyton a branching system of two orders, with Psilophyton pubescens üsel and Weyland (1933), the continu- ription and good illustrations. . The fertile part is missing. Berry and Fairon- d by Skimmers et al. (1933) ewicz identified the specie üsel and Weyland’s specimens were lost; a neotype from It was thought to be manicum Demaret dated the locality to late Eifelian. ously dichotomized “fertile pinnae”gia and differ the from paired those sporan- of together with other plantflora. fossils to determine the age of the up to three dichotomousthe vegetative second-order appendages axes, attached to whichGermany resembles and USA. Sporangiaures are are seemingly not in clear pairs. enough Fig- Weyland (1938). Schweit and recognized it asthey a described variety it of in the German. genus flora. the genus is unconvincing. Kirberg was designated. Detailedillustrations. description and good The vegetative branching and the anatomy resemble The plant strongly resembles the type species except for spines. From the figures of Kra Kra Aneurophyton üsel and Weyland üsel and Weyland and Fairon-Demaret 2001 2002 1932, 1933; Obrhel 1961 1923, 1926, 1929; Schweitzer and Matten 1982 lian Leclercq 1940; Berry Table 1 Late Givetian Jurina 1988 Only the name is mentioned. Givetian? Stepanov 1975 Stepanov (1975) shows Givetian Jurina 1988 Only the name was mentioned. Early Givetian Kra FrasnianLate Givetian Serlin and Banks Jurina 1978 1969 Detailed desc Identifie Occurrences of Taxa Attributed to ´, Belgium Latest Eife Ukraine sion, southwestern Siberia, Russia Russia Germany York, USA Kazakhstan Goe Wuppertal-Elberfeld, Southeastern New ... Donbass Basin, ... Timan-Pechora region, ... Aktobe, Kazakhstan Late Eifelian Jurina 1988 Sienki ... West of Ulenty, All use subject to JSTOR Terms and Conditions permineralization permineralization permineralization Compression/ Compression Wuppertal, Germany Early Givetian Schweitzer and Giesen Compression Bohemia, Czech Mid-Devonian Kra Compression? South Minusa Depres- Compression/ Compression/ This content downloaded from 119.78.212.207 on Sat, 21 Dec 2013 04:16:45 AM pubescens var. germanicum A. germanicum cf. A. bohemicum cf. A. germanicum A. A. germanicum A. germanicum ? A. germanicum SpeciesA. germanicum Conservation Locality Age Reference(s) Comments and notes A. germanicum A. germanicum

1196 . Aneuro- A. ger- . Matten ation” branch- Aneurophyton erved, hindering -type trunks, con- Psilophyton pubes- afﬁnity apart from (2012) designated it (Schweitzer and Gie- reported the species A. erianum -type branches. Stein a The “trifurc ile part pres pubescens Triloboxylon arnoldii owed no difference from var. Eospermatopteris Aneurophyton . Prestianni et al. a vegetative branching system, which maroccanum. rrienne et al. (2010) insist on its status ” , indicating a different . The plant needs further study. . discovered the fossils. b , although under the name of Wattieza A. germanicum Aneurophyton . Its paired lateral branches at the insertion allow ” and lost. New specimens from Kirberg were desig- Aneurophyton Aneurophyton and the associated plants; studied by Krishtofovich. manicum from our point of view sh et al. (2007) foundxylopsid that the trunks wereAneurophyton attached by clado- phyton comparison with Stenokoleales. ing is reminiscent ofHowever, Xinjiang this and plant German has nofurther fert comparisons. 1974 on the basis of anatomical study. put into as “ sidered by Goldring (1924)the and trunks Serlin connected and to Banks (1978) as Coenopteridales. Ge in cens nated as sen 2002). Banks (1966) illustrated Berry (2008) thought the specimen may not belong to The fossils are actually the The plant was transferred to The plant preserves only the vegetative part and is hard to be Schweitzer and Matten (1982) thought the plant belonged to The original specimens were described as “ kmans 1948; Ger- ¨usel and Weyland 2008 1966; Serlin and Banks 1978 and Banks 1971; Matten 1974 1950; Prestianni et al. 2012 rienne et al. 2010 1932 Late Eifelian Jurina 1988 Nikitin (1934) Mid-Devonian Stockmans 1968; Berry Givetian Goldring 1924; Banks Eifelian Termier and Termier Late Givetian Jurina 1969 Medoyev (1936) and Baluhoneky (1937) ¨t Abdallah, lgium Late Fammenian Stoc ork State, USA Givetian Arnold 1940; Scheckler Voronezh, Russia Belgium USA Morocco Kazakhstan All use subject to JSTOR Terms and Conditions Compression Petina and Semiluki Compression Massif du Brabant, Permineralization New Y Compression Dechra Aı Cast/impression Gilboa, New York, Compression Onle, Be Compression Wuppertal, Germany Devonian Kra This content downloaded from 119.78.212.207 on Sat, 21 Dec 2013 04:16:45 AM Aneurophyton sp. (?) ... Karaganda Basin, furcatum See p. 99 in Jurina 1988. See p. 8 in Jurina 1969. (?) a b A. pubescens Possible species of A. A. hallii “Aneurophyton” maroccanum A. erianum A. olnense Aneurophyton ?

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Fig. 15 Schematic architectural models showing the fertile portion in Aneurophyton doui sp. nov. A1–A3, Fertile organ axis with oppositely arranged sporangia in different view. A1, The short stalked (st) sporangia (s) are borne pinnately along the organ axis (P). A2, Adaxial view. Note that the sporangia are attached to the organ axis adaxially and form a distichous pattern. A3, Lateral view. Note the organ axis recurving adaxially. B1–B3, Fertile organ axis with alternately arranged sporangia in different view. C, D, Two complex fertile organs showing oppositely arranged P2 axes. The lyre-shaped system in German Aneurophyton germanicum is shown in D. E, Diagram of a complex fertile organ. The organ is a pinnate system up to three orders; all orders of fertile axis (P1, P2, P3) can bear sporangia directly, and P1 and P2 can also bear the organ axes of higher order simultaneously. conform to the three-dimensional branching system helically ulate. In addition, their vegetative appendages, although with arranged in A. doui. Some German fossils (named as Protop- the same dichotomized pattern as in the Xinjiang species, are teridium thomsonii; Schweitzer and Matten 1982) bear a “tri- planated structures (Scheckler and Banks 1971) rather than furcation” when the main axis gives out a pair of laterals, like three dimensional. the paired second-order axes in A. doui. Paleophytogeographical Significance Comparison with Species of Tetraxylopteris Aneurophyton probably has only two valid species, the type The two species in Tetraxylopteris, T. schmidtii Beck 1957 species and our new species. Other species need more speci- and T. reposana Hammond et Berry 2005, exhibit the fertile mens to show identifiable features, have been or should be organs with two dichotomies and three orders of pinnae bear- transferred to other genera, or need more information to val- ing elongate ovoid, fusiform sporangia with acute apices idate publication (table 1). (Bonamo and Banks 1967; Hammond and Berry 2005). This The genus has a wide distribution in the Middle-Upper De- fertile organ is more complex than that of Rellimia and is also vonian of Laurussian and other paleoblocks, including A. ger- distinctive from that of the present species. manicum from the Middle Devonian of Germany (Kraüsel and The vegetative and fertile branching system of Tetraxylopteris Wayland 1923, 1926), Belgium (Leclercq 1940; N. Momont, follows an opposite, decussate pattern (Beck 1957; Scheckler personal communication), and the United States (Serlin and and Banks 1971; Hammond and Berry 2005). Aneurophyton Banks 1978); some uncertain species of Aneurophyton from doui, however, branches spirally or dichotomously, being dif- the Middle Devonian of Siberia, Ukraine (Jurina 1988), and ferent from either species of Tetraxylopteris. Kazakhstan (Jurina 1969); and A. olnense from the Upper Devonian of Belgium (Stockmans 1948). It is also noteworthy Comparison with Triloboxylon ashlandicum that other taxa of the order Aneurophytales also have restricted Matten et Banks 1966 occurrences in the Middle-Upper Devonian of eastern Lau- Triloboxylon ashlandicum and the present plant have sim- russia and northwestern Gondwana (Gerrienne et al. 2010). ilarities, including the same helical arrangement of branch- The locality of A. doui sp. nov. is a part of the West Junggar ing, the small number (20–40) of sporangia in one fertile volcanic arc (Xiao et al. 2010), with the primary lithologies organ, the pinnate arrangement of sporangia in the last seg- being basalts and volcanoclastic sediments, which consist of a ment, and a longitudinal dark-lined hinge or dehiscence slit thin strip of volcanic islands orientated NW–SE and lying out- through the sporangia (Scheckler 1975). However, Tr. ash- board of the core of what became Kazakhstan and separated landicum differs from the present plant in that the fertile from it by a subduction zone (Zhou and Dean 1996). Aneu- organs are borne in the middle of the vegetative branches rophyton from the Middle Devonian of North Xinjiang is the (Scheckler 1975)—not distally or on specialized fertile first occurrence of Aneurophytales outside both margins of the branches, as it seems in A. doui—and the sporangia are apic- Rheic Ocean. In addition, the spores of aneurophytalean pro-

This content downloaded from 119.78.212.207 on Sat, 21 Dec 2013 04:16:45 AM All use subject to JSTOR Terms and Conditions JIANG ET AL.—MID-DEVONIAN ANEUROPHYTON FROM CHINA 1199 gymnosperms, Rhabdosporites langii (Balme 1995), has nu- Acknowledgments merous Devonian occurrences. It is suggested that Aneurophy- tales originated from northern Gondwana (Gerrienne et al. We thank Dr. Tang P. (Nanjing Institute of Geology and 2010) and that by the end of the Devonian they spread to a Paleontology, CAS) for help in Xinjiang ﬁeldwork; P. Giesen nearly global distribution. The West Junggar arc probably acted (Wuppertal, Germany) and N. Momont (University de as a land route or near continuous land area in the dispersal of Lie`ge, Belgium) for their instructive discussions and kindly some Devonian lycopsids, as is indicated by the presence of the photographing German and Belgium specimens of Aneu- megaspore Verrucisporites and the miospore Cymbosporites in rophyton for us; A. B. Doweld (National Institute of Gondwana, West Junggar, and northern Euramerica (Marshall Carpology, Russia) for his warm help with Russian et al. 2007; Xu et al. 2012a). In the Paleozoic, the West Junggar literature. This research is supported by the National 973 arc got closer to Kazakhstan and probably played a key role in Project (2012CB821901) and the National Nature the dispersal of Aneurophytales from Ukraine, Siberia, Kazakh- Sciences Foundation of China (41221001, 41172013, and stan to western Gondwana, and other paleoblocks. 41272001).

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