Vidalina radoicicae Cherchi & Schroeder, 1986

SIMMONS, MICHAEL & BIDGOOD, MICHAEL, 2023, “ Larger ” Benthic Foraminifera Of The Cenomanian. A Review Of The Identity And The Stratigraphic And Palaeogeographic Distribution Of Non-Fusiform Planispiral (Or Near-Planispiral) Forms, Acta Palaeontologica Romaniae 19 (2), pp. 39-169 : 104-108

Vidalina radoicicae Cherchi & Schroeder, 1986

Reference Illustration & Description

Cherchi & Schroeder (1986), pl. 1. figs. 1-3, 5, p. 185- 188.

Vidalina is a relatively simple genus consisting of a subspherical proloculus followed by an unsegmented post embryonic tubular chamber arranged in a planispiral coil. The wall is porcelaneous, and the aperture is a simple opening at the end of the tube. Additional lamellae are laid down with each coil, so the central part of the coil is continually thickened. V. radoicicae – first formally described from the late Cenomanian of the Anglona region, NW Sardinia by Cherchi & Schroeder (1986) – has a more-or-less lenticular axial cross-section with 6- 7 adult coils. Of the other known species, Vidalina hispanica Schlumberger (see Decrouez et al., 1978; Farinacci, 1991; Schlagintweit, 1992), has more coils (12-14), is larger (maximum equatorial dimension 1.0- 1.5mm compared with 0.25-0.43 mm) and is more disc-like with a thick central boss rather than being lenticular, whilst V. discoidea Schlagintweit is very disc-like with only limited umbilical thickening ( Schlagintweit, 1992). V. carpathica Neagu & Popescu is not thought to range above the Barremian ( Neagu & Popescu, 1966). See the Species Key Chart (Appendix) for diagnostic and other characteristics.

V. radoicicae is thought to be restricted to the Cenomanian whereas V. hispanica was first described from the Santonian, although Schlagintweit (2008) suggests V. hispanica could have been identified (as the type material of Nummoloculina regularis Philippson – a view disputed by Piuz & Vicedo (2020)) from as old as the Late Turonian in Austria. Cherchi & Schroeder (1986) consider that V. hispanica is possibly a descendant of V. radoicicae .

V. radoicicae can potentially be confused with nummoloculinids in equatorial views if the post-embryonic chamber appears segmented. “ Short indentations of the wall from the upper side into the tube lumen ” were observed by Schlagintweit (2008) in specimens he regards as V. hispanica (see above), giving a false appearance of chambering. Axial views are potentially confusable with taxa such as Charentia cuvillieri (see Korbar et al., 2012). Ideally, both axial and equatorial views are required to confirm illustration but are seldom provided in the literature.

Some authors ( Chiocchini et al., 2012 from the Italian Apennines (as “? V. radoicicae ”, late Cenomanian); Jez et al., 2011, from Slovenia (as “ Vidalina cf. radoicicae ”, late Cenomanian); Tentor & Tentor 2007, from northeast Italy (late Cenomanian); Solak et al., 2020, from the Turkish Taurides (middle – late Cenomanian) have illustrated axial views of forms identified as Vidalina but which do not show the characteristic lenticular axial profile of V. radoicicae and whose specimens appear rather more parallel-sided and are confusable with Pseudonummoloculina? regularis herein. These are treated as unconfirmed and may represent as yet undescribed taxa. On the other hand, specimens of Vidalina appear to be easily transported and often appear to be abraded or coated in micrite, making the true external shape difficult to determine.

Ghanem & Kuss (2013) illustrate “ Vidalina cf. radoicicae ” from the late Aptian of northwest Syria, but these specimens are clearly very distinct from true V. radoicicae and represent a different taxon. This is also true for their late Albian “ Vidalina sp. ”. The equatorial view of a specimen attributed to V. radoicicae by Ghanem & Kuss (2013) has some hints of chamber segmentation and is also therefore regarded as unconfirmed – note that these authors regard this species as being of biozonal value and useful for distinguishing the late Cenomanian (see below).

Stratigraphic Distribution

(Late early?) middle – late Cenomanian.

V. radoicicae was first recorded from the late Cenomanian (associated with Cisalveolina fraasi ) of western Serbia as “ Vidalina sp. 1 (nov. sp.?)” by Radoičić (1972). Subsequently it was formally described from the late Cenomanian of Sardinia ( Cherchi & Schroeder, 1986), and has been regarded as a marker for this substage by some (e.g., Velić & Vlahović, 1994; Velić, 2007; Rahimpour- Bonab et al., 2012; Ghanem & Kuss, 2013), but a literature review suggests a longer range into at least the middle Cenomanian.

All confirmed illustrated material are assigned a late Cenomanian or middle – late Cenomanian age. From Italy, these include Barattolo (1984) (as Vidalina sp. ); Foglia (1992) (late middle – early late Cenomanian); Benedetti et al. (2000) (early late Cenomanian); Simone et al. (2012) (middle Cenomanian) and Frijia et al. (2015) (late Cenomanian); from Greece Fleury (1971) (as Nummoloculina regularis ); Decrouez et al. (1978) (as V. hispanica ); from Croatia Velić & Vlahović (1994) and Velić (2007); from the Turkish Taurides Tasli et al. (2006) (middle – late Cenomanian), Sari et al. (2009) (middle – late Cenomanian), Solak (2021) (as “ Vidalina sp. ”) (middle – late Cenomanian) (the illustration by Solak et al., 2017 is more uncertain); and from the Iranian Zagros Rahimpour-Bonab et al. (2012) (late Cenomanian) and Mohajer et al. (2021a) (late Cenomanian). An illustration by Schlagintweit & Rigaud (2015) from the late middle – early Cenomanian of Kosovo is uncertain. An illustration of “ Vidalina sp. ” by Hamaoui (1962) from the late (?) Cenomanian of Israel may be V. radoicicae .

Records unconfirmed by illustration are assigned to ages confined within the Cenomanian, mostly middle – late Cenomanian. From Spain these include Calonge et al. (2002, 2003); from the Italian Apennines Bravi et al. (2006); Chiocchini (2008a, 2008b); Chiocchini et al. (2008); Mancinelli & Chiocchini (2006); Parente et al. (2007, 2008) – who places the LAD of V. radoicicae within the geslinianum ammonite zone, Frijia & Parente (2008); Spalluto (2011) and Spalluto & Caffau (2010); from the Balkans Brčić et al. (2017) (the specimen illustrated by Brčić (2015) is probably Charentia cuvillieri , but that by Brčić et al. (2021) (late Cenomanian) may be valid), Božović (2016), Husinec et al. (2000), Del Viscio et al. (2022); and from the Iranian Zagros Mohajer et al. (2022a, 2022b), Omidvar et al. (2014b) and Rahimpour-Bonab et al. (2013). An unillustrated record by Cruz-Abad (2018) is from the early Cenomanian of the Italian Apennines, as is a somewhat uncertain illustrated record by Bravi et al. (2004), and if valid they would be the oldest records known. “ Vidalina sp. ” from the supposed early Cenomanian of southeast Turkey ( Ozkan & Altiner, 2019) (but possibly middle Cenomanian (see Simmons et al., 2020b)) is a distinctly separate taxon.

Cenomanian Paleogeographic Distribution

Neotethys.

Not particularly widely reported except for the area around Italy and the Balkans but confirmed as far east as the Iranian Zagros.