Kloster and Gnaedinger—Agathoxylon wood anatomy from La Matilde Formation, Argentina
araucarioid). Pits are circular (100%), araucarioid, uniseriate (51%), alternate biseriate (24%), uniseriate partially biseriate, alternate (16%) and opposite (7%), and triseriate and bi-triseriate, alternate (2%). The size of the pits is 11–15μm×11–15μm. The pits exhibit a circular aperture, which measures 7.5μm(Figs. 4.6, 6.2, 6.4, 6.5).Cross-fields are araucarioid, having 2–8, 10 pits that are circular, with circular or sometimes elliptical apertures,whose frequency range is 3–4 pits, arranged in groups or crown-shaped or in two or three horizontal rows (Figs. 4.7, 4.8, 6.6–6.8). The pits measure 12–15μm in diameter and the apertures from 4μm to 11μm; some of the radial cells end in a pointed shape. In TLS, the radial system is homogeneous with homocellular rays, uni- seriate, of 1–12 cells in height; the average is 4–5 cells. The cells at both ends are elliptical and the centers are rectangular or quadrangular, measuring 15–52μmhigh by 15–30μm wide. In addition, the rays show differences in the height of the central radial cells of the same rays; some radial cells measure 17–20μm and others 6–11μm (Figs. 6.9, 10).
Materials.—Gran Bajo de San Julián sector: Cerro Conito: CTES-PB 10675 (CTES-PMP 2408-2409); CTES-PB 10693 (CTES-PMP 2381); CTES-PB 10696 (CTES-PMP 2391); CTES-PB 10697 (CTES-PMP 2392); CTES-PB 12004 (CTES- PMP 2390); CTES-PB 12017 (CTES-PMP 2438); CTES-PB 14265 (CTES-PMP 3540 a, b, c); CTES-PB 14266 (CTES-PMP 3541 a, b, c); Northern part of Ea. Meseta Chica: CTES-PB 12041 (CTES-PMP 2459); CTES-PB 12043 (CTES-PMP 2465- 2466); CTES-PB 12052 (CTES-PMP 2472).
Remarks.—Specimens identified as Araucarioxylon termieri (Attims) Gnaedinger andHerbstmatch with the description made by Giraud and Hankel (1985) for Dadoxylon (Araucarioxylon) termieri Attims and with the anatomical characters of the holo- type given by Attims (1965) (see Giraud and Hankel, 1985). In addition, these specimens fromArgentina show differences in the height of the central radial cells within the same ray, as in the
specimen from Tanzania (Giraud and Hankel, 1985, pl. 13, fig. 3). Tables 1 and 2 summarize the observed anatomical fea- tures of five samples fromthe LaMatilde Formation and showthe numerical differences in the percentages of the seriation and combination of the radial pitting, but, always with a greater per- centage of uniseriate pits, like the specimens from Africa. Araucarioxylon termieri (Attims) Gnaedinger and Herbst is
similar to other species of Agathoxylon (Araucarioxylon)from Gondwana in sharing the presence of circular pits in the radial walls of the tracheids, and is distinguished by the seriation and distribution of pits in the radial tracheid walls, the number of pits in the cross-fields, and the ray height (Table 4). However, A. termieri is identical to the Permian species Araucarioxylon allani (Kräusel) Maheshwari in presenting in the radial walls of the tracheids araucarioid, circular, uniseriate, biseriate, and rarely triseriate pits, and uniseriate, low rays, with a height of 1–12 cells (Kräusel, 1962) (Table 4); and, therefore they are probably synonymous.
Agathoxylon santacruzense new species Figures 7, 8
Holotype.—CTES-PB 12012, CTES-PMP 2433 a, b, c. Paratype.—CTES-PB 12013, CTES-PMP 2434 a, b, c.
Diagnosis.—Wood type (tracheid radial pitting) is araucarian (100% of the contiguous pits are araucarioid). Pits are araucar- ioid, uniseriate, flattened, and circular; alternate biseriate, circular, and hexagonal; uniseriate, partially biseriate, alternate, circular, hexagonal-flattened; and opposite circular, hexagonal-flattened in a pair or several pairs (japonicum type); and triseriate and bi- triseriate, alternate circular and hexagonal. Cross-fields are arau- carioid, with 2–14, 20 pits, circular, with elliptical or sometimes circular apertures, whose frequency range is 6–8 pits, arranged in disordered groups or crown-shaped or some in two or four hor- izontal rows. The rays are homogeneous, mostly uniseriate, and the height in number of cells is 1–16, 20.
Occurrence.—La Matilde Formation, Santa Cruz Province, Argentina (Middle Jurassic).
Description.—Fragments of logs found in situ of 1.5m in dia- meter, with 1m height preserved, and a fallen trunk with visible dimensions of 1.50m in length and 60cm in diameter were studied. These materials came from the southeastern border of Laguna del Carbón locality. The following description is based on specimen CTES-PB 12012, which consists of a fragment of secondary xylem, pycnoxyilic, with distinct growth rings. In TS, the tracheids of the early wood are rectangular-ovoidal and polygonal in the shape. Tracheids of the early wood have an average radial diameter of 47µm(36–60µm) and tangential dia- meter of 37µm(24–52µm). In the late wood, the tracheids have a tangential average diameter of 35µm(24–40µm) and radial dia- meter of 21µm(16–28µm). The average number of tracheids that separate the rays is 7–8, varying between 2–18 tracheids. The rays are presented in a continuous way through the section (Fig. 7.1). In RLS, the wood type (tracheid radial pitting) is ara- ucarian (100% of the contiguous pits are araucarioid). Pits are araucarioid, uniseriate (9.6%[7–12%]), flattened (2.6%[1–4%]), and circular (7% [6–9%]); alternate biseriate (44.6% [39–51%]), circular (32.6% [29–36%]), and hexagonal (12% [10–15%]); uniseriate partially biseriate (37% [36–38%]), alternate, circular (22%[21–24%]), hexagonal-flattened (6%[5–8%]), and opposite circular (2%[1–3%]), hexagonal-flattened in a pair (4%[3–5%]) or in several pairs (japonicum type) (3% [2–4%]); and triseriate and bi-triseriate, alternate circular (1% [1–2%]) and hexagonal (6% [5–8%]). The size of the pits is 12–16μmand 20μm×10 μm. The pits present a circular aperture, which measures 4–6μm (Figs. 7.2–7.5, 8.1–8.4). Cross-fields are araucarioid, having 2–14, 20 pits that are circular, with an elliptical or some- times circular aperture, whose frequency range is 6–8pits, arranged in disordered groups or crown-shaped or some in two or four horizontal rows. The pits measure 8–10μmand theapertures are elliptical measuring from 4–8 μm×3μmor circular and 2.5–4 μm (Figs. 7.5–7.7, 8.1–8.5). The rays are homogeneous andmost uniseriate, the height in number of cells is 1–16, 20, the average is 6 cells. The cells at both ends are elliptical and the centers are rectangular or quadrangular, measuring 15–52μm high×15–30μmwide (Fig.7.8).
Etymology.—In reference to Santa Cruz province, Argentina, where the analyzed wood was found.
557
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168 |
Page 169 |
Page 170 |
Page 171 |
Page 172 |
Page 173 |
Page 174 |
Page 175 |
Page 176 |
Page 177 |
Page 178 |
Page 179 |
Page 180 |
Page 181 |
Page 182 |
Page 183 |
Page 184 |
Page 185 |
Page 186 |
Page 187 |
Page 188 |
Page 189 |
Page 190 |
Page 191 |
Page 192 |
Page 193 |
Page 194 |
Page 195 |
Page 196 |
Page 197 |
Page 198 |
Page 199 |
Page 200 |
Page 201 |
Page 202 |
Page 203 |
Page 204 |
Page 205 |
Page 206 |
Page 207 |
Page 208 |
Page 209 |
Page 210 |
Page 211 |
Page 212 |
Page 213 |
Page 214 |
Page 215 |
Page 216 |
Page 217 |
Page 218 |
Page 219 |
Page 220 |
Page 221 |
Page 222 |
Page 223 |
Page 224 |
Page 225 |
Page 226 |
Page 227 |
Page 228 |
Page 229 |
Page 230 |
Page 231 |
Page 232
