Myrtoidea PASSALIA , ROMERO, PANZA, 2001

Greguš, Josef & Kvaček, Jiří, 2015, Revision Of Cenomanian Flora From The Maletín Sandstone, Acta Musei Nationalis Pragae Series B 71 (3 - 4), pp. 315-364 : 326

Myrtoidea PASSALIA, ROMERO, PANZA, 2001

T y p e: Myrtoidea patagonica PASSALIA, ROMERO,

PANZA, 2001, p. 74, fig. 2A–E.

D i s c u s s i o n. When describing the genus Myrtophyllum, Heer (1869) described two species: M. geinitzii and M. schuebleri . However, he did not publish a generic diagnosis of the genus. Due to the description of two species, diagnosis generico specifica is ruled out. A generic diagnosis of the genus Myrtophyllum was published later by Schimper (1874), who validated the name Myrtophyllum , and both species M. geinitzii and M. schuebleri . The situation was seemingly solved; however, Z. Kvaček (1992) discovered that the genus Myrtophyllum HEER is a younger homonym of the recent genus Myrtophyllum TURCZANINOW 1863 from the family Flacourtiaceae ( Farr et al. 1979) . This fact precludes use of the genus Myrtophyllum , and it is therefore necessary to find a new genus for plants sharing characters of fossil Myrtophyllum HEER ex SCHIMPER.

The genus Myrtoidea described by Passalia et al. from the Late Cretaceous of Bajo de los Corrales, Santa Cruz Province, Argentina ( Passalia et al. 2001) is suggested here as an adequate name that could substitute for homonymous Myrtophyllum . First, it is preserved as a leaf impression, its cuticle is not known. Secondly, it possesses a clearly distinguished intramarginal vein. As already pointed out by Passalia et al. (2001) an intramarginal vein cannot be used as a character for identification of a family. For example, Myrtoidea patagonica is thought to have affinities to Myrtaceae , while our material is probably of lauralean affinity. But due to its poor preservation, without knowledge of its cuticle, Myrtoidea is a suitable fossil genus for leaf impressions of unknown systematic affinity bearing intramarginal veins. However, there are more genera similar to Myrtoidea / Myrtophyllum . Daphnophyllum HEER is semihomonymous with Daphniphyllum BLUME (see Z. Kvaček 1992). The genus Eucalyptophyllum FONTAINE is based on E. oblongifolium , material from the Early Cretaceous of the Potomac Formation ( Fontaine 1889). It is a fragment of a leaf with poorly developed secondary veins, and lacking any sign of an intramarginal vein. Finally, the genus Eucalyptolaurus COIFFARD, GOMEZ, THIÉBAUT et J. KVAČEK in Coiffard et al. 2009 differs from Myrtoidea in the presence of paracytic stomata and other epidermal details, which indicate its systematic affinity to the Laurales .