Daxia cenomana Cuvillier & Szakall, 1949

Reference Illustration & Description

Arnaud-Vanneau and Prestat (in Schroeder & Neumann, 1985), Pl. 1, figs. 1-8, p. 15.

The genus Daxia, along with the type species, D. cenomana, was introduced by Cuvillier & Szakall (1949) based on material from the late Cenomanian of western France. It is a biumbonate to flattened form, planispirally enrolled and evolute, with numerous (~ 15 in macrospheric forms; ~ 22 in microspheric forms) sickle or teardrop shaped chambers, wider at the base than at the outer wall. Loeblich & Tappan (1988) confirmed that the aperture of Daxia is a single areal opening, just above the base of the apertural face. The suggestion that Daxia has a “spiral canal” (as in many rotaloideans including nummulitids) (Laug & Peybernès, 1979) was demonstrated as invalid by Cherchi & Schroeder (1980).

Daxia is similar to Biconcava, which is more evolute and, in particular, to Mayncina Neumann (type species Daxia orbignyi Cuvillier & Szakall, described alongside D. cenomana). In axial sections M. orbignyi has a more inflated profile, compared to the acute periphery of D. cenomana, and in megalospheric forms, a much larger proloculus (up to 190 μm, compared to up to 100 μm in D. cenomana). Note the sickle-shaped chambers in equatorial sections of D. cenomana, that reduce in height from base to outer wall in comparison to the more regular chamber height in M. orbignyi (Dr. Felix Schlagintweit, pers. comm., 2022). See the Species Key Chart (Appendix) for diagnostic and other characteristics.

The key difference of a single aperture in Daxia and multiple apertures in Mayncin a (Loeblich & Tappan, 1988) can be difficult to observe in thin-section. Many random thin-sections cannot be separated at the generic level. Loeblich & Tappan (1988) pointed out that specimens of D. cenomana illustrated by Neumann (1965) are in fact M. orbignyi (an error overlooked by Arnaud & Prestat in Schroder & Neumann, 1985).

Other potential confusion taxa include a number of poorly known forms such as Deuterospira Hamaoui (type species Deuterospira pseudodaxia) reported only from the Cenomanian of Israel and Iraq (see Hamaoui, 1979) which has a low number (typically only 2) of coils, a basal/interio-marginal aperture and a sharp, angular periphery (see herein). Another similar genus, but poorly known, is Stomatostoecha Applin, Loeblich & Tappan, 1950 (Type species: Stomatostoecha plummerae Applin, Loeblich & Tappan, 1950) described from the Albian of Texas.

It is said to differ from Daxia by the presence of an extensive slit-like aperture (Maync, 1972). However, Mikhalevich (2004b) regarded the aperture as a vertical row of rounded openings based on the figures of the holotype in Loeblich & Tappan (1988). It has recently been mentioned from the mid-Cretaceous of Tibet (e.g., BouDagher-Fadel et al., 2017) but without illustration. Finally, Phenacophragma Applin, Loeblich & Tappan, 1950 (Type species: Phenacophragma assurgens Applin, Loeblich & Tappan, 1950) is similar but with an aperture as a slit at the top of the apertural face. See also Phenacophragma oezeri Solak & Tasli described from the Albian of Turkey (Solak & Tasli, 2020). All these potential confusion taxa require thorough taxonomic revision.

Daxia minima Laug & Peybernès is a smaller and older form of Daxia, first described from the Aptian of Spain; Laug & Peybernès, 1979) and has relatively thicker septa and more depressed sutures. However, the dimensions for D. cenomana given by Schroeder & Neumann (1985) and compared with those given for D. minima by Laug & Peybernès (1979) – see below – do show some slight overlap which means that smaller macrospheric specimens of D. cenomana might be confused with larger specimens of D. minima.

D. minima D. cenomana

Equat. Diam. 0.37 – 1.10 mm 0.73 – 1.60 mm Axial Diam. 0.14 – 0.30 mm 0.28 – 0.65 mm

Proloc. Diam. 40 – 50 microns 40 – 100 microns

Arnaud-Vanneau & Prestat (1985) do however state that their measurements are taken from ‘A’ (macrospheric) forms only. ‘B’ form (microspheric) measurements of D. cenomana based on earlier data from Neumann (1965, 1967) quoted in Laug & Peybernès (1979) but not quoted in Schroeder & Neumann (1985) are larger: Equatorial diameter = 2.0 – 2.7 mm, Axial diameter = 1.0 mm.

Stratigraphic Distribution

Late Albian – late Cenomanian.

D. cenomana was first described from the late Cenomanian of Landes, France (Cuvillier & Szakall, 1949; Saint-Marc, 1966). More recently, Andrieu et al. (2015) report D. cenomana from the middle and late Cenomanian of Aquitaine with good stratigraphic calibration from carbon isotopes but provide no illustration.

It was regarded by Arnaud-Vanneau & Prestat (in Schroeder & Neumann, 1985) as restricted to, but ranging throughout the Cenomanian, but only limited evidence was provided in support. Nonetheless, subsequent more globally extensive records (see below), would suggest that a range throughout the Cenomanian and older into the late Albian is likely.

For example, records from Spain are extensive (see also Arnaud-Vanneau & Prestat (in Schroeder & Neumann, 1985) and include beautifully illustrated material by Hottinger (1967), illustrated middle Cenomanian occurrences by Bilotte (1973, 1985), and records from the early Cenomanian by Calonge et al. (2002, 2003, not illustrated) and from the early-middle Cenomanian by Caus et al. (2009, not illustrated). Cherchi & Schroeder (1998, not illustrated), also report undifferentiated early – middle Cenomanian records from Spain, whilst Gräfe (2005, not illustrated) notes that the species is common in undifferentiated Cenomanian sediments of northern Spain. Hofker (1965) illustrated it as Haplophragmoides cenomana from the Aptian - Albian transition of Spain, where it was said to range from Aptian – Cenomanian – this may be because of inclusion of taxa now regarded as D. minima in the species concept (see also Arnaud-Vanneau, 1980). Finally, Ramirez del Pozo (1972) records the species from the Cenomanian of Spain as Haplophragmoides cenomana, but the illustrations are insufficient to confirm identification.

Dr Felix Schlagintweit (pers. comm., 2022) has indicated that D. cenomana can be found in the late Albian of the Iranian Zagros, and possibly Tibet, where it is said to be common in the Langshan Formation (Albian – early Cenomanian) (see also Smith & Juntao, 1988 illustrated as Daxia sp. and thought to be late Albian based on associated orbitolinids; and Fossa Mancini, 1928 - unnamed foraminifera pl. XXII, fig. 10). Yang et al. (2015); BouDagher-Fadel et al. (2017); Xu et al. (2019, 2021); and Rao et al. (2020) mention but do not illustrate Daxia from Tibet.

Berthou & Lauverjat (1979) and Berthou (1984b) indicated that the species can be found throughout the Albian – middle Cenomanian of western Portugal but provided no illustration (see also Berthou & Schroeder, 1978; Boavida, 2013; Cabral et al., 2014, not illustrated). Andrade (2018) has illustrated the species from the Cenomanian of Portugal (pl. M2, fig. 1) but other illustrations (e.g., pl. M5, fig. 5) are equivocal and may be M. orbignyi.

Luger (2018) described and illustrated an equatorial section of “ Daxia cf. cenomana ” from the “latest Albian” of Somalia. As noted by Luger (2018), the specimen has a much smaller proloculus than the material described by Arnaud-Vanneau & Prestat (in Schroeder & Neumann, 1985), and the identification is hard to validate from a single equatorial section.

The suggestion by Omidvar et al. (2014a, 2014b) that it may occur in Turonian strata in the Iranian Zagros is neither substantiated by illustration nor associated microfauna. Rare occurrences recorded from the Turonian Buttum Formation in Egypt by Samuel et al. (2009) are also unsubstantiated by illustration and/or are likely misidentified.

Well-illustrated, independently biostratigraphically or chemostratigraphically calibrated records of this species are required.

Cenomanian Paleogeographic Distribution

Possibly Pan-Neotethyan.

Arnaud-Vanneau & Prestat (in Schroeder & Neumann, 1985) only noted limited records from France and Spain. Since then, there are many more published records, which if valid, extend the distribution from the middle – late Cenomanian of Mexico in the west (Omaña et al., 2012, 2016, 2019, illustrated, but specimens may be M. orbignyi) to the Cenomanian of Tibet in the east (see above).

The species has been commonly reported from the early – late Cenomanian of Egypt (e.g., Shahin & Kora, 1991; Kora et al., 1994; Shahin, 2007; Ismail et al., 2009; Shahin & Elbaz, 2013, 2014; Deaf & Tahoun, 2018; El Baz & Khalil, 2019; El Baz & Kassem, 2020, but only material illustrated by El-Sheikh & Hewaidy, 1998 from supposedly late Cenomanian strata approaches plausibility based on illustration, although the critical axial section mentioned in the plate caption is missing from the actual plate).

There are many (mostly unillustrated) records from the Iranian Zagros (e.g., Afghah & Fadaei, 2014; Kiarostami et al., 2019; Dehghanian & Afghah, 2021; Omidi et al., 2021) but only the illustration of Mohajer et al. (2021a) approaches plausibility, from supposedly late Cenomanian strata. Illustrations by Afghah et al. (2014) (= Pseudorhipidionina ex gr. casertana-murgiana) and Jamalpour et al. (2018) (too few low chambers, nondeterminable simple specimen) are not this species. Elsewhere in the Middle East there are possible records from Kuwait (El-Naggar & Al-Rifaiy, 1973, not illustrated).

Other unillustrated records include Parente et al., (2007) who reported it from the late Cenomanian of Italy, co-occurring with Cisalveolina fraasi (Gümbel); from the Cenomanian of Albania (Peza & Pirdeni, 1994); Provence (southern France) (Babinot et al., 1988) and Algeria (Alloul, 2019).

A record from Jordan (Weidich & Al-Harithi, 1990) is indeterminate. A record from Armenia (Danelian et al., 2014) is of Charentia cuvillieri.

In summary, despite multiple records of this species from many locations, substantive illustrations are lacking. Only Cenomanian records are shown on Figure 8.