Sprecher
Beschreibung
The monocot family Hydrocharitaceae is morphologically characterised by a strong adaptation to aquatic habitats. Members of the family show the greatest variability among aquatic angiosperm families comprising both freshwater and marine species.
We describe fossil fruits from the Turonian-Santonian of the South Bohemian Cretaceous Basin in Czechia. Bonaquella is characterised by radially digitated fruits consisting of a single, unilocular carpel, with an anatropous ovule with basal placentation. The fruit is flat, ovate and indehiscent, covered by papillae in central part and fringed by large multicellular, branched emergences laterally. Its style is straight, unbranched, and occasionally shows an annular swelling in its basal part. The single seed is broadly ovate with the hilum next to the micropyle. The seed coat consists of a thin and smooth testa and a tegmen consisting of quadrangular cells covered by delicate micro-tubercles; in the micropylar area cells decrease in size having anticlinal cell walls thickly cutinised.
Bonaquella shares a number of characters with Hydrocharitaceae, including indehiscent fruits, the presence of well-developed style, and having a micropyle developed from its inner integument. Its tegmen shows similar cells covered by delicate micro-tubercles. Anatropous ovules are found in the family, they are known e.g., from Stratiotes and Najas. The most important character of Bonaquella is the presence of micro-tubercles on the tegmen. This character is synapomorphic for all members of the Hydrocharitaceae.