Hausmannia faltisiana 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 : 405-408

Hausmannia faltisiana Stipanicic and Menéndez, 1949 emend. herein

Fig. 6B, C .

1949 Hausmannia (Protorhipis) faltisiana sp. nov.; Stipanicic and Menéndez 1949: 8–9, pl. 1: 4, pl. 2: 1–5; text-fig. 1.

1949 Hausmannia (Protorhipis) dentata Ôishi 1932 ; Stipanicic and Menéndez 1949: 6–7, pl. 1: 1–3.

1992 Hausmannia faltisiana Stipanicic and Menéndez, 1949 ; Herbst 1992a: 47–48.

Type material: Lectotype: BAPb 6249 , part and BAPb 6254 , counterpart (designated by Herbst 1992a) . Paralectotypes: BAPb 6248 , part and BAPb 6256 , counterpart (designated by Herbst 1992a); all from type locality .

Type locality: Cortaderita Creek , Barreal-Calingasta Depocenter, San Juan Province, Argentina .

Type horizon: EF3, Barreal Formation, Sorocayense Group, Anisian (Middle Triassic).

Material.— Type material only.

Emended diagnosis.—Petiolate fronds, orbicular, with a strongly lobate margin. Large regular lobes with triangular shape, rounded apex and entire to irregularly and slightly undulate margins. Number of lobes ranging 14–22. Base of the frond lamina composed of two equal, opposite rachial arms. Each arm gives rise to 7 to 11 catadromous to isodromous primary veins. Primary veins striate and straight to slightly sinuous. Secondary veins subopposite, departing at angles of 45–80° from primary veins. Secondary veins smooth and sinuous, dichotomizing three times to form a fine reticulate mesh of polygonal areoles. First order areoles regular and polygonal elongated, second order areoles slightly irregular polygonal.

Description.—The studied material are the original specimens described by Stipanicic and Menéndez (1949). They are two specimens with their counterparts, and correspond to orbicular petiolate fronds, of 4–6 cm in diameter. Only the apical part of the petiole is preserved. The frond lamina has a strongly lobate margin, forming 14–22 regular lobes. These lobes have a triangular shape, rounded apex and entire to irregularly and slightly undulate margin. They reach 1.7 cm of heigth and 0.8 cm of width. The base of the lamina is composed of two equal, opposite rachial arms; each one gives rise to 7 to 11 catadromous to isodromous primary veins. The primary veins are straight to slightly sinuous. 0.5 cm wide. The secondary veins are subopposite, and depart at angles of 45-80° from primary veins. They are smooth and sinuous, dichotomizing three times to form a fine reticulate mesh of polygonal areoles. First order areoles regular and polygonal elongated up to 4× 7 mm in size, second order areoles slightly irregular polygonal, up to 1 mm in size. Sori and sporangia are not observed. See Stipanicic and Menéndez (1949) for full description.

Remarks. — Stipanicic and Menéndez (1949) described the fronds of two species of Hausmannia : H. (Protorhipis) dentata and the new species H. (Protorhipis) faltissiana . As noted afterwards by Herbst (1992a), the materials assigned to both taxa are very similar and belong to the same species: Hausmannia faltisiana , considering the fact that they share the characters defined by Stipanicic and Menendez (1949) (i.e., lamina orbicular, of 4–5.5 cm in diameter, strongly lobate margin, high and regular lobes with triangular shape, rounded apex and entire margin, primary veins straight, secondary veins departing at angles of 45–80°, first order areoles polygonal regular and elongated 2× 4 mm in size, second order areoles polygonal less regular, 0.6× 0.8 mm in size). Hausmannia faltisiana differs from H. dentata Ôishi, 1932 (described for the Upper Triassic of Japan; see Table 2) in shape and size of the lamina (semi-orbicular to reniform and with a maximum diameter of 12 cm in the second one), the margin of the lobes (undulate in H. dentata ), the course of the primary veins (slightly sinuous in the last one), and the second order areolas (which are inconspicuous in H. dentata ). Even though Stipanicic and Menéndez (1949) mentioned most of the characters of H. dentata in some specimens from Barreal Formation ( BAPb 6248, 6256), when we revised the materials, they show more similarities with H. faltisiana (e.g., the diameter of the lamina between 5–7 cm and conspicuous second order areoles). The shape of the lamina (defined as semi-orbicular by Stipanicic and Menéndez 1949) is actually unknown due to fact that the samples are fragmentary and could possibly be orbicular as in H. faltisiana . Finally, although the margin of the lobes seems to be undulate as in H. dentata , the undulations are much scarcer, more irregular and shallow that in the Japanese species. In line with the proposal of Herbst 1992a), we transferred the samples determined as H. dentata to H. faltisiana , and emended the specific diagnosis of the last one in order to include the morphological variability in the margin of the lamina lobes.

Stratigraphic and geographic range.— Type locality and horizon only.

Figures

Fig. 6. Dipterid ferns from Barreal-Calingasta, San Juan Province, Argentina. A, D–F. Dictyophyllum tenuifolium Stipanicic and Menéndez, 1949 emend. Bonetti and Herbst, 1964; Cortaderita Formation (Ladinian, Middle Triassic). A. PBSJ 412a. D. PBSJ 1051. E. PBSJ 412b. F. PBSJ 412c. B, C. Hausmannia faltisiana Stipanicic and Menéndez, 1949 emend. herein; Barreal Formation (Anisian, Middle Triassic). B. BAPb 6248. C. BAPb 6254. Scale bars: A, C, D, 10 mm; B, 20 mm; E, F, 5 mm.