B. Papp szerk.: Studia Botanica Hungarica 30-31. 1999-2000 (Budapest, 2000)

Rákosi, László; Barbacka, Mária: Upper Cretaceous flora from Ajka (W Hungary). I. Thallophyta

Remarks: This species was described from English Weal den by HORST (1954, p. 610). Later HUGHES (1955), who interpreted it as perisporium of megaspore, described it under the name Triletes retiarius. However, his illustrated sample differs from the typical Dictyothylakos. POTONIÉ (1956) created a new genus, Thylakosporites, and placed the Huges species into this genus. The Dictyothylakos fragments of perisporium have never been mentioned as found together with the body of spore and their taxonomic appurtenance was kept on discussing. In HUEBER's opinion (1982, pp. 15-17) Thylakosporites and Dictyothylakos should be regarded as different genera. This way the genus Dictyothylakos was described from the Lower Cretaceous of the Netherlands and Egypt (DIJKSTRA 1961), from Alberta: Albian (SINGH 1964) and Upper Cretaceous (GUNTHER and HILLS 1972), from Hettangian of Poland (MARCINKIEWICZ 1971) as well as from North Dakota from the Paleocene (MELCHIOR and HALL 1983). The latter authors supposed that the perisporium may belong to Trichoptera. La Pasha and MILLER (1985) also described the Dictyothylakos and noted that it was composed of very resistant materials. In Hungary it is relatively common in the vicinity of Ajka. Incertae sedis Genus: Costatheca (Miner 1935) Hall 1967 Generotype: Costatheca (al. Chrysotheca) discoënsis (Miner 1935) Hall 1967 Costatheca discoënsis (Miner 1935) Hall 1967 Figs 20-21, 30-31 Description: Seed cuticles variable in shape, oblong, ovate, lanceolate or elliptic. Dimensions: 600-1800 pm long and 150-600 pm wide. Seed anatropous with a micropyle around the short funicle. Often with striations. Remarks: This species was emended by BlNDA and NYAMBUDIRI (1983), and by KNOBLOCH (1986). A number of species is known from Albian deposits (BATTEN and ZAVATTIERI 1996). In the examined material C. discoënsis is frequent, in the borehole Gy-9 dominant in the level of 590.4 m. There are two unusual forms in the material, with numerous, different shaped one-cell spores of fungi inside (Fig. 34). It appears questionable that those specimens really belong to genus Costatheca; they are either perithecia of fossil Mycophyta or zoosporangia (Saprolegniaceae). This question may be justified because JANSONIUS et al. (1981) proved that Geleenites fascinus