Pseudorhapydionina laurinensis ( De Castro, 1965 )

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 : 117-121

Pseudorhapydionina laurinensis ( De Castro, 1965)

Reference Illustration & Description

De Castro in Schroeder & Neumann (1985), Pl. 43, p. 91- 95. Good illustrations of this species are provided by Chiocchini et al. (2012) (see also Sartorio & Venturini, 1988).

The genus Pseudorhapydionina was introduced by De Castro (1972), with Rhapydionina laurinensis as described by De Castro (1965) from the early late Cenomanian of southern Italy as the type species. In contrast to Rhapydionina Stache – an alveolinid with a thick, perforated basal layer – Pseudorhapydionina – a soritid without a thick perforated basal layer – has a somewhat simpler, less complex endoskeleton where pillars and blades do not fuse to form marginal chambers and a pre-septal void, which is characteristic of the former. Beams are irregularly alternating between well developed and less well developed and are numerous (De Castro in Schroeder & Neumann, 1985). De Castro (1972) also introduced the closely related genus Pseudorhipidionina . Pseudorhapydionina is essentially globular to (uncoiled) subcylindrical whereas Pseudorhipidionina is flatter and (uncoiled) flabelliform. Loeblich & Tappan (1988) describe a cribrate aperture in both genera, although pores are “scattered” in Pseudorhapydionina and present as “a row of pores” in Pseudorhipidionina . Demirina also has internal septula, although fewer, and with a more ‘peneroplid’ overall shape and Praetaberina possesses pillars which Pseudorhapydionina lacks ( Consorti et al., 2015).

The treatment of the genus and of P. laurinensis by De Castro in Schroeder & Neumann (1985) is comprehensive and allows for confident identification. See also the description and illustrations from Sapin in Calonge-Garcia (1996). Consorti et al. (2016b) tabulates differences between the various species of Pseudorhapydionina , although comparative stratigraphic ranges are not discussed. They provide a useful succinct description of P. laurinensis : “ porcelaneous, subgloblar-to-cylindrical shell. The subglobular early stage, with a size of about 0.33 mm of diameter, consists of two whorls of planispiral chambers. The first whorl hosts six chambers, while the second one has ten. The diameter of the proloculus is approximately 30 μm. The height of the cylindrical chambers is approximately 0.05 mm. The chamber lumen is partially divided by long radial septula, which number approximately 5-6 per quadrant in the seriate stage of growth [though illustrations show more]. Septula thickness is around 15 μm. ” See the Species Key Chart (Appendix) for diagnostic and other characteristics.

P. laurinensis differs from all other Pseudorhapydionina species in having a somewhat flared uncoiled, seriate portion (especially in the early part) whereas other uncoiled species ( P. chiapanensis and P. dubia ) have more-or-less parallel-sided seriate portions. P. laurinensis also has more depressed sutures on the seriate part compared to the other species. P. anglonensis has no uncoiled portion but this is subject to further investigation.

The four species of Pseudorhapydionina recorded herein ( P. chiapanensis Michaud et al. , P. dubia (De Castro) , P. laurinensis (De Castro) and P. anglonensis Cherchi & Schroeder ), all have a stratigraphic record limited to within the Cenomanian. A Santonian species from the Pyrenees, P. bilottei Consorti et al. (2016b) , is not discussed in detail here, although it was based on specimens assigned to P. laurinensis by Bilotte in 1984. Compared to P. laurinensis , it has a greater maximum diameter of the early planispiral stage and number of chambers per whorl. The radial septula of P. laurinensis are longer but thinner than in P. bilottei ; moreover, the width/height ratio of the seriate chambers is higher in P. laurinensis than in P. bilottei (see Consorti et al., 2016b).

P. laurinensis was introduced in 1965 by De Castro, but forms that are this species had been known for some time under different names. These include “ Ouladnailla ” nom. nud. by Emberger (1955) from the Cenomanian of Algeria and “ Taberina sp. (sp. nov?)” of Hamaoui (1961) illustrated from the Cenomanian of Israel.

Stratigraphic Distribution

Middle – late (but not latest) Cenomanian.

As a genus, Pseudorhapydionina seems to have evolved in the early (?earliest) Cenomanian by a species referred to as P. aff. laurinensis in Iberian sediments of the Chera Formation ( Consorti et al. 2016a; see also De Castro in Schroeder & Neumann, 1985, who mentions P. laurinensis from the early Cenomanian of Italy, although without illustration).

De Castro (1965) and De Castro in Schroeder & Neumann (1985) indicated that the type material of P. laurinensis is from the early part of the late Cenomanian. The notion that the species is restricted to this age interval has been followed by a number of authors, potentially sometimes with circular reasoning for the age assignment. Saint-Marc (1974a, 1978, 1981, illustrated) constructed a P. laurinensis Total Range Zone for the “lower part of the upper Cenomanian” of Lebanon, with age constrained from other fauna. Fleury (1971) illustrated P. laurinensis from rocks attributed with a late Cenomanian age from Greece, although the presence of the species was cited as one of the arguments for the age assignment. On the other hand, Decrouez (1978) recorded (with uncertain illustration) P. laurinensis together with Conicorbitolina conica (d’Archiac) in Greece. The latter species ranges no higher than middle Cenomanian ( Schroeder & Neumann, 1985). Calonge-Garcia (1996) follows De Castro (1985) in restricting the species to the middle and (lower) late Cenomanian of Spain.

Velić (2007, unillustrated) confined the total range of P. laurinensis to his Vidalina radoicicae-Chrysalidina gradata Concurrent Range Zone , to which he assigned a late Cenomanian age, in the Dinarides of the Adriatic coast. In sections from Morocco where there is good ammonite-based age calibration, P. laurinensis occurs (illustrated) within the late but not latest Cenomanian ( Charrière et al., 1998) (see also Ettachfini & Andreu (2004); Ettachfini et al. (1989, 2005) and Ettachfini (2006) for unillustrated or uncertain records). Consorti et al. (2016b) record and illustrate a sensu stricto form from the late Cenomanian of the Iberian Ranges of Spain (see below for discussion of another form described as “ P. aff. laurinensi s”).

Chiocchini & Mancinelli (1977), Chiocchini (2008a, b) and Chiocchini et al. (2008, 2012) use the total range of P. laurinensis in Central Italy to define a “ P. dubia and P. laurinensis biozone” which encompasses much of what they term “late Cenomanian”, but not the latest. Note however, that they do not use the term middle Cenomanian, so the meaning of their “late Cenomanian” most likely incorporates some middle Cenomanian of the current international standard.

Similar occurrences may have led Arnaud et al. (1981) to consider the range of P. laurinensis as middle – possibly upper Cenomanian in the Mediterranean region, a view upheld in the range chart of Schroeder & Neumann (1985), although as discussed above, its presence in the lower part of the late Cenomanian appears certain. Orabi et al. (2012) (with plausible illustration) constructed a P. laurinensis zone of middle Cenomanian age in Egypt with the FAD of P. laurinensis as the base zonal marker although it is shown ranging to the top of the overlying biozone which is assigned a (lower) late Cenomanian age (see also Shahin & Elbaz 2013, 2014).

The form referred to as P. aff. laurinensis by Consorti et al. (2016b) deserves further discussion. Consorti et al. (2016b) illustrated this form but gave no other diagnostic means of separating it from P. laurinensis s.s. other than that it was “smaller”. There is a suggestion in the single illustration that the aff form may have fewer septula than the s.s. form. The aff form is also uncoiled which suggests it is not a juvenile. Comparison between the figures in Consorti et al. (2016b: aff form Figure 4a, s.s . form Figure 4b – both are equatorial sections) shows the aff form is about 75% the size of the s.s. form with both illustrations shown as being smaller than the scale bar of 0.5mm length. P. aff. laurinensis was recorded from the Chera Formation, near Castellon in Spain which is shown as being latest Albian to earliest Cenomanian in age.

Another possible record of the genus stated to be early Cenomanian are specimens designated as P. cf. laurinensis by Luger (2018) from Somalia. However, Luger’s illustrations are more equivocal, and the specimens are not oriented favourably although the uncoiled (seriate) part does at least seem cylindrical. This makes size measurement of the specimens difficult, but the maximum dimension appears to be around 1.8mm – much larger than Consorti et al.’s (2016b) P. aff. laurinensis . Luger’s specimens occur with Praealveolina iberica Reichel which can range into the middle Cenomanian, so an early Cenomanian age is not definite.

In our view the specimens from Spain designated P. aff. laurinensis ( Consorti et al., 2016b) may – until more material is examined – be regarded as “primitive” examples of P. laurinensis but may be a separate taxon. The specimens of Luger (2018) from Somalia are more equivocal but with better age calibration may be included within P. laurinensis or P. dubia . There is insufficient material to consider a separate taxon.

In summary the overall consistent range of P. laurinensis appears to be from the middle to the late but not latest Cenomanian, but the range locally – especially the position of the FAD – appears to be strongly facies-restricted. Specimens “comparable with” or which have “affinity” with P. laurinensis have been recorded from the early Cenomanian (in more peripheral localities – see below) but their exact taxonomic relationship with P. laurinensis s.s. needs further examples and study. A Maastrichtian record (Bilotte, 1978) is known to be erroneous ( Bilotte, 1984).

Cenomanian Paleogeographic Distribution

Neotethys.

In addition to the references cited above, P. laurinensis is recorded with confirmed or plausible illustration from the late Cenomanian of Albania / Kosovo ( Consorti & Schlagintweit, 2021a); the Dinarides ( Radoičić, 1972, 1974a; Velić & Vlahović, 1994); and the Turkish Taurides ( Bignot & Poisson, 1974; Sari et al., 2009; Solak et al., 2020). Unillustrated records or records with questionable illustrations are from Serbia ( Radoičić & Schlagintweit, 2007); Albania ( Heba, 2008); Tunisia ( Philip et al., 1988; Saïdi et al., 1995; Touir et al., 2017); Syria ( Mouty et al., 2003; Ghanem et al., 2012); Israel ( Hamaoui, 1966); Dubai ( Menegatti, 2004) and Oman ( Smith et al., 1990; Piuz & Meister, 2013).

It seems likely that P. laurinensis does not occur in Mexico, being replaced by the similar, but endemic form, P. chiapanensis ( Aguilera-Franco, 2003) . Unillustrated records of P. laurinensis from Mexico ( Hernández-Romano et al., 1997; Aguilera-Franco et al., 2001) may therefore be of P. chiapanensis .

The forms above designated as “cf” from Somalia are included as unconfirmed occurrences here.

A questionable illustration from Algeria ( Alloul, 2019) is indeterminate – but see Hamaoui & Fourcade (1973) for confirmed records from there. They also illustrate specimens from Israel. P. laurinensis is regarded as important for biozonation in the Mishrif Formation of southern Iraq ( Al-Dulaimy et al., 2022), but the illustration is not this species or even genus (probably = Biconcava bentori ), however, illustrations by Mohammed (2005) from the same rock unit seem plausible (see also Al-Salihi & Ibrahim, 2023 for an unillustrated record). Interestingly, there is no reliable record of the species from the Iranian Zagros.

Figures

Fig. 4 Distribution map of type descriptions/specimens in this study.