Taeniopteris lentriculiformis (Etheridge) Walkom, 1917

Flores-Barragan, Miguel Angel & Leon, María Patricia Velasco-de, 2020, New records of Bjuvia and Nilssonia from the Permian of Mexico, Palaeontologia Electronica (a 28) 24 (3), pp. 1-17 : 11

Taeniopteris lentriculiformis (Etheridge) Walkom, 1917

Figure 4 C-D

Material. CFZMTZ-330.

Locality. Coatepec.

Description. Entire lamina, with entire margins, probably oblong in shape, leaf width appears to be constant. The apex and base are not preserved. The leaf is 4.1 cm long and 2.5 cm wide. The lamina attaches laterally to the rachis. The rachis is slim, retaining its width throughout the whole leaf with a maximum width of 0.2 cm. The fine veins emanate from the rachis at 90°. The venation is simple, rarely dichotomous, with a density of 23 to 24 veins per cm at the middle-part of the leaf.

Remarks. Given the general morphology of the leaf, this specimen resembles an isolated pinna of the genus Danaeopsis Heer ex Schimper. However , this taxon is characterized by having strong secondary veins that anastomose near the margin. Even though there are species that can lack anastomoses, such as D. angustifolia and D. fecunda ( Kustatscher et al., 2012a) , the differences in leaf size, vein angle, and venation density do not allow assignation to these species. In addition, the lack of compound leaves and/or sporangia that determine the affinity of these specimens makes their comparison with this genus impossible. For this analysis, the specimen from Puebla was compared with 42 species of the fossil taxon Taeniopteris described for the Permian-Triassic ( Table 4 ). The observations indicate a higher similarity with the species Taeniopteris lentriculiformis , which is characterized by the near absence of bifurcations in the veins. Yet the size of its lamina is comparable to that of T. vittata Brongniart , it does differ due to the lower venation density of T. lentriculiformis ( Artabe, 1985) . This species has been reported for the Triassic of Argentina, New Zealand, and Australia ( Artabe, 1985; Rettallack, 1985).

Figures

FIGURE 4. Specimens of leaves of Cycadophytes. A) Nilssonia sp. Specimen CFZ-MTZ266, the arrow indicates an area in which it is observed how the leaf covers the rachis. B) Parallel and dichotomous venation of Nilssonia sp. C) Parallel venation of Taeniopteris lentriculiformis, specimen CFZ-MTZ330. D) Specimen of Taeniopteris lentriculiformis. E) Taeniopteris crassinervis, specimen CFZMtz-713. F) Parallel and dichotomous venation of Taeniopteris crassinervis. Symbols: m, leaf margin; r, rachis; the arrows indicate the areas with dichotomous venation. Scale. A, D-F 1 cm, B and C 0.5 cm.