Hausmannia sp.

Pole, Mike, 2019, Middle-Late Jurassic plant assemblages of the Catlins coast, New Zealand, Palaeontologia Electronica (a 51) 23 (3), pp. 1-48 : 13-14

Hausmannia sp.

Figure 7

Material. Otara-36: LX2361.

Description. Lamina presumably originally reniform, with a medial distal notch and other less prominent notches along the distal margin. Base truncate, at 90° to the petiole. Height 40 mm, preserved width 35 mm, indicating an original width of c. 70 mm. Sori not obvious. Petiole midvein bifurcates at the base, then at least three more times before the margin. Intervening lamina is divided into a reticulate, polygonal, mesh.

Remarks. On the basis of its reniform (or broadly fan-shaped) lamina, dichotomising major veins, and reticulate mesh of higher venation, a single specimen from Otara Beach is clearly a Hausmannia . Cantrill (1995) pointed out that Hausmannia is indistinguishable from extant Dipteris and is, therefore, best regarded as an organ-genus of Dipteris . He noted that extant Dipteris show such a wide range of morphology that “few taxa could be recognised in the fossil record,” although a few characters, including the degree of marginal lobing, could reliably distinguish species. Unfortunately, the margin of the new specimen is partially damaged, but what does remain indicates relatively shallow crenulations, with the exception of the apical sinus, clearly not deeply dissected. On that basis it is probably pointless to search for a “specific” match for the single specimen here, although the shape of the Otara Hausmannia compares favourably with fan-shaped Hausmannia from the Lower Cretaceous of Western Australia (McLoughlin, 1996; McLoughlin and Hill, 1996; McLoughlin and McNamara, 2001; Peyrot et al., 2019), and the Northern Territory (White, 1961). In contrast, it differs from the more distinctly reniform Middle Jurassic Hausmannia from the Clarence-Moreton Basin (Gould, 1980; McLoughlin and Drinnan, 1995) and the more deeply dissected Hausmannia wilkinsii from the Gilbert River Formation (Lower Cretaceous) of Cape York (Walkom, 1928).

Recent works covering the Dipteridaceae from the Australasian-Antarctic region include Herbst (1979), Rees (1993), Cantrill (1995) and Rees and Cleal (2004). The later reidentified all Dictyophyllum from the Antarctica Peninsula as Goeppertella , and Rees (1993) recognised Goeppertella from the New Zealand’s Clent Hills. Dictyophyllum has been reported from the Catlins in the past (Arber, 1917; Herbst, 1979), but not encountered during the present study. Future study may indicate they are also Goeppertella . Rees (1993) regarded Goepertella as stratigraphically significant — for instance using its presence in the New Zealand Clent Hills assemblage to argue for a Late Triassic or Early Jurassic age, in contrast to Oliver et al. (1982) who proposed a Middle to Late Jurassic age (although note the Hunter et al., 2005, reassessment of the Botany Bay Group as mid Jurassic).