Velleditsiella, Rigaud & Blau, 2016

Rigaud, Sylvain & Blau, Joachim, 2016, New robertinid foraminifers from the Early Jurassic of Adnet, Austria and their evolutionary importance, Acta Palaeontologica Polonica 61 (4), pp. 721-734 : 723-725

Genus Velleditsiella nov.

Etymology: In honor of Felicitász Velledits (Institute of Mineralogy and Geology, University of Miskolc, Hungary) for her paleontological contributions.

Type species: Velleditsiella felicitaszae gen. et sp. nov.; see below.

Species included: The type species and V. spinaferra gen. et sp. nov.

Diagnosis.— Trochosiphoniinae with pear-shaped chambers directly open on the siphon.

Remarks.— Velleditsiella gen. nov. shows similarities to the agglutinated genus Siphovalvulina Septfontaine, 1988 from which it differs mainly in its wall composition, in the smoothness and straighter morphology of its siphon (in Siphovalvulina , the siphon is twisted), and in its direct openings on the siphon, which are distinct from the aperture.

From its Late Triassic homeomorphic ancestor Trochosiphonia Rigaud, Martini, and Vachard, 2015b , it differs only in its pear-shaped chambers (chambers are ovoid in Trochosiphonia ) and in the presence of an opening between each chamber and the siphon.

The foraminiferal affinity of this new genus is incontestable as Velleditsiella gen. nov. possesses a proloculus (Figs. 2C, O, 3L) and well-distinct chambers, which are clearly separated by septa and all connected by a foramen (Figs. 2C, F, H–K, 3G, I). However, when specimens of Velleditsiella gen. et sp. nov. are tangentially or obliquely sectioned, on account of their aragonitic lamellar wall and trochospiral coiling, they may be confused with microgastropods. Microgastropods are larger (even their larval shells), not primarily bilamellar and do not possess so thin and tightly distributed perforations. Tangential sections of the tube of a microgastropod will never show septation. Moreover, the variability observed through ontogeny in the dimension (Figs. 2A 1, N, 3A, B, D–G, K–N) and number of lumina (compare the number of lumina on both sides of the siphon in Figs. 2B, N, 3A, E–G, M) would be aberrant for a microgastropod.

Like other aragonitic fossils found in our samples, all specimens of Velleditsiella gen. nov. are completely recrystallized into calcisparite. The apparent, relatively good state of preservation in the structure of some specimens is related to Fe-Mn impregnation processes (e.g., Figs. 2A, B, E, M, 3H, M).

In Robertinida , the presence of a siphon is unique to the family Trochosiphoniidae and the connection of each chamber with the siphon is limited to the genera Pragsoconulus and Velleditsiella gen. nov. In these two taxa, additional openings have been most likely used as secondary apertures, allowing shorter connections between each chamber and the surrounding environment.

Stratigraphic and geographic range.—Uppermost Hettangian–lowermost Sinemurian (Lower Jurassic) of Austria.