Dictyophyllum castellanosii Stipanicic and Menéndez, 1949

Bodnar, Josefina, Drovandi, Juan Martín, Morel, Eduardo Manuel & Ganuza, Daniel Gustavo, 2018, Middle Triassic dipterid ferns from west-central Argentina and their relationship to palaeoclimatic changes, Acta Palaeontologica Polonica 63 (2), pp. 397-416 : 400-401

Dictyophyllum castellanosii Stipanicic and Menéndez, 1949

Fig. 3 .

1949 Dictyophyllum castellanosii sp. nov.; Stipanicic and Menéndez 1949: 9–11, pl. 3: 1–4, text-fig. 2.

1992 Dictyophyllum (Dictyophyllum) castellanosii Stipanicic and Menéndez, 1949 ; Herbst 1992a: 25–26.

Material.— BAPb 6227, part and BAPb 6228, counterpart; EF3, Barreal Formation, Sorocayense Group, Anisian (Middle Triassic), Cortaderita Creek, Barreal-Calingasta Depocenter, San Juan Province, Argentina.

Description.—The revised material corresponds to the type specimens of the species. They are part and counterpart of a fan-shaped once-pinnate frond of 7 cm in diameter. The rachis dichotomizes into two arms, each one bearing 4 or 5 linear-lanceolate pinnae. The basal web of lamina unites adjacent pinnae for a length of 1 cm. The free part of pinnae reaches 6 cm in length and 0.8 cm in width. The margin of the pinnae is lobate-serrate. The lobes are ovate-acuminate. The primary veins of the pinnae are slightly sinuous. Secondary veins are subopposite, departing at angles of 45–52° from the primary veins. Tertiary veins are subopposite, and depart from secondary veins at an acute angle. They dichotomize succesive times to form a reticulate mesh of polygonal areoles. First order areoles are elongated, and second order areoles are isodiametric. Sori and sporangia are not observed. See Stipanicic and Menéndez (1949) for full description.

Remarks. — Stipanicic and Menéndez (1949) erected this species on the basis of one specimen ( BAPb 6227) and its counterpart ( BAPb 6228). This taxon is similar to species of Dictyophyllum having a lobate, but not pinnatifid, pinna margin, i.e., D. exquisitum Sun, 1981 , D. nathorstii Zeiller, 1903 , and D. serratum (Kurr in Schimper, 1869) Frentzen, 1922 (from the Upper Triassic of Asia), and D. ellenbergii Fabre and Greber, 1960 (from the Upper Triassic of South Africa). However, D. castellanosii can be clearly distinguished from the Asiatic species (see Table 1) due to the number of pinnae per arm (up to 5 in the Argentinean taxon and more than 5 in the remaining ones) and the shape of the pinna lobes (ovate-acuminate in D. castellanosii ; triangular or falcate, but not acuminate, in the other species). On the other hand, D. castellanosii is different from D. ellenbergii due to the venation areoles, which have an irregular shape in the last species. Unfortunately, we did not find more samples of the species in the fossiliferous strata of the Sorocayense Group. Until today, D. castellanosii has not been recorded in other localities of Argentina or elsewhere.

Stratigraphic and geographic range. —Anisian of Barreal Formation, Sorocayense Group, San Juan Province, Argentina.

Figures

Fig. 3. Dipterid fern Dictyophyllum castellanosi Stipanicic and Menéndez, 1949, from Barreal Formation (Anisian, Middle Triassic) of Barreal-Calingasta, San Juan Province, Argentina. BAPb 6227, part (A) and BAPb 6228 counterpart (B). Scale bars 20 mm.