Orbitolina duranddelgai Schroeder, 1972

Orbitolina duranddelgai Schroeder, 1972 View in CoL

1951 Orbitolina conoidea – Cuvillier & Sacal, pl. 26, fig. 1 Late Albian, France.

1963 Orbitolina lenticularis – Hofker jr., pl. 17, fig. 5; pl. 20, fig. 2, 4-6. Albian – Cenomanian transition, Spain.

1964 Orbitolina (O.) concava concava – Schroeder, p. 688-690, text-fig. 3a-d. Albian – Cenomanian transition, Spain.

1965 Orbitolina conica – Saint-Marc, pl. 4, fig. 2; pl. 14, fig. 7. Early Cenomanian, France.

T 1972 Orbitolina (Orbitolina) duranddelgai n. sp. – Schroeder, p. 114-116; text-fig. 2-3 Albian – Cenomanian transition, Spain.

1973 Orbitolina (O.) duranddelgai – Bilotte, pl. 1, fig. 1- 4; pl. 4, fig. 9 Latest Albian, Pyrenees, France.

1973 Orbitolina (O.) duranddelgai – Schroeder, text-fig. 2-3 Albian – Cenomanian transition, Spain.

1976 Orbitolina (O.) duranddelga i – Peybernes, p. 394; pl. 31, fig. 3-4; pl. 32, fig. 18-19 Latest Albian, Spain 1976 Orbitolina (O.) duranddelgai – Cherchi & Schroeder, p. 1217; text-fig. 1 Latest Albian – early Cenomanian, Sardinia.

? 1977 Orbitolina (O.) duranddelga i – Rey et al., p. 378; pl. 2, fig. 7 Latest Albian, Portugal.

1984 Orbitolina (Orbitolina) duranddelgai – Bilotte, p. 364, pl. 1, fig. 10 (figs. 5-9 uncertain). Latest Albian, Pyrenees.

1985 Orbitolina (O.) duranddelgai – Schroeder in Schroeder & Neumann, p. 68-70, pl., 31, fig. 1-9 late Albian, Spain.

Non 1993 Orbitolina (Orbitolin a) duranddelgai – Bravo & Garcia, pl. 3(1). Appears similar to O. qatarica , but best classified as Orbitolina spp. in the absence of definitive sections.

Diagnostic features: An Orbitolina with a proloculus of diameter 0.25 – 0.30mm and height 0.14 – 0.16mm, and which is irregularly ellipsoidal or cup-shaped. The embryonic apparatus diameter is 0.50 – 0.70mm (max 0.80mm). The supra-embryonic zone is highly subdivided. The sub-embryonic zone is thin, and only weakly subdivided. Radial zone chamber passages are numerous and densely-spaced, oval to squarish.

Remarks: This species was introduced by Schroeder (1972) for an Orbitolina with numerous, small, oval – squarish radial chamber passages, more densely spaced than in Orbitolina concava and an embryonic apparatus 0.5-0.7 mm (0.8 mm max) in diameter.

Stratigraphic range: Very latest Albian – earliest Cenomanian (confident and common). Based on the type material from Spain, the species was originally considered as Cenomanian, but corrected (for the type material) to latest Albian (dispar zone = approximately rostratum/perinflatum zones fig. 3 herein) by Schroeder in Schroeder & Neumann (1985). Nonetheless, it was (mistakenly) considered a useful early Cenomanian zonal fossil by Schroeder (1973, 1975). Following discussion of the age range by Bilotte et al. (1978) and Berthou & Schroeder (1978), O. duranddelgai was further described by Schroeder in Schroeder & Neumann (1985) with a suggested short range of latest Albian to earliest Cenomanian. The Cenomanian extension to the range was established from records with Praealveolina from France and Spain (Debuyser & Schroeder, 1972; Peybernes, 1976; Babinot et al., 1991; Caus et al., 1993, 2009; Calonge et al., 2003; Calonge-Garcia & Lopez- Carillo, 2003; Consorti et al., 2016). Nonetheless, Schroeder et al. (1993) noted its value as a marker for the latest Albian in eastern Spain (see also Bilotte et al., 1978; Moullade et al., 1985) and Bilotte (1984) illustrated material from the latest Albian of the French Pyrenees. Martin-Chivelet (1994) considered it an early Cenomanian marker in Spain, thereby emphasising the possibility of short local ranges.

The need to observe both sections of the embryonic apparatus and the chamber passages led Castro et al. (2001) and Bachmann et al. (2003) to use the term “ Orbitolina sefini / duranddelgai ”, with Luger (2018) emphasising the difficulty of identifying Orbitolina sensu stricto species in the absence of multiple suitably oriented sections. Bachmann et al. (2003) considered “ Orbitolina sefini / duranddelgai ” to potentially range from the inflatum zone (= approximately cristatum -fallax zones fig. 3 herein) of the late Albian – middle early Cenomanian (restricted to the late Albian in northern Sinai) but provided no illustrations.

Palaeogeographic distribution: The species may be endemic to the western Mediterranean (northern margin of Neotethys), with most viable records from Spain or the French Pyrenees. The only records from the Arabian Plate are those of Afghah & Fanati Rashidi (2007) from the (Albian) Kazhdumi Formation of the Iranian Zagros (not illustrated) and BouDagher-Fadel (2018) (identification and stratigraphic position uncertain, but not O. duranddelgai ). Therefore, O. duranddelgai appears to be absent from the Arabian Plate, a view supported by Dr. Mohsen Yazdi-Moghadam (pers. comm., 2024).