Peneroplis parvus 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 : 110-112

Peneroplis parvus De Castro 1965

Reference Illustration & Description

De Castro in Schroeder & Neumann (1985), Pl. 39, p. 86- 88.

Originally described as Peneroplis planatus (Fichtel & Moll) n. ssp. parvus, the type and subsequent descriptions of the species by De Castro (1965, 1985) are comprehensive and allow for confident identification (see also Calonge-Garcia, 1996; p. 38, pl. 2, figs. 8-13). A peneropolid with a porcelaneous, imperforate wall and multiple cribrate apertures. 5-6 chambers in the first whorl, 7- 11 in the last (second) whorl. May become flabelliform. The species is very similar to the extant Peneroplis planatus (Fitchell & Moll) , but with a smaller size (equatorial diameter c. 0.82mm), plus more adult chambers per mm (11.5-17.5). See the Species Key Chart (Appendix) for diagnostic and other characteristics.

P. parvus is amongst the oldest known representatives of Peneroplis , a genus often regarded as restricted to the Cenozoic and Recent ( Loeblich & Tappan, 1988; BouDagher-Fadel, 2008). Chiocchini (2008a) introduced Peneroplis cairoensis from the initial part of their late Cenomanian (=intra-middle Cenomanian) of central Italy. This species is slightly larger than P. parvus (c. 1.2 mm diameter), has a greater number of chambers in the uncoiled stage and a larger diameter of apertural pores. It has not been recorded from outside its type area and is not considered further. Peneroplis aragonensis is a species introduced from the late Albian of the Spanish Pyrenees by Peybernès (1984) as Broeckinella? aragonensis and subsequently transferred to Peneroplis by Schlagintweit & Rashidi (2020). This species is much larger than P. parvus (diameter c. 4.5mm) with a tendency to become sub-annular in macrospheric forms. It too has not been recorded outside its type area and is not considered further. Saint-Marc (1974a) illustrated a “ Peneroplis sp. ” from the late Albian of Lebanon. This is a rapidly uncoiling form, broader and more rounded than P. parvus in axial section, and slightly larger. Consorti (in Consorti et al., 2018) introduced a new genus and species, Pseudopeneroplis oyonensis , from the upper Cenomanian of Peru. In contrast to Peneroplis this taxon develops subdivisions in the marginal area of the chamber lumen but is otherwise similar.

A potential confusion species is Neodubrovkinella turonica Said & Kenawy. Originally described as a species of Peneroplis (“ Peneroplis turonicus ”) from Egypt ( Said & Kenawy, 1957), this taxon has been shown by Schlagintweit & Yazdi-Moghadam (2022a) to be a biokovinid (and Cenomanian, not Turonian). In well-preserved material the finely agglutinating wall with a pseudo-keriothecal structure is visible, excluding it from the Miliolida . In specimens where the wall structure is not clear, a large proloculus in megalospheric forms, a tendency to rapidly uncoil with chambers enlarging rapidly, are sufficient to distinguish N. turonica from P. parvus , as is occasional streptospiral coiling in early chambers. It is worth noting that in many thin-sections, and even illustrations of three-dimensional specimens, the porecellanous nature of the wall of P. parvus can be difficult to determine.

Stratigraphic Distribution

Late Albian/early Cenomanian – late Cenomanian.

The stratigraphic range of P. parvus has been the subject of a range of opinions in the literature. In his original description, De Castro (1965) thought the type material (from central Italy) to be probably middle Cenomanian in age, a view maintained by him in 1985 (De Castro in Schroeder & Neumann, 1985), although he considered the overall range to be latest Albian to intra-middle Cenomanian based on his assessment of known occurrences to that time. However, in 1991 he considered that in the broad type area an upper Albian – lower Cenomanian biozone could be introduced based on the total range of the species. Similarly, Chiocchini et al. (2012) illustrated the species and limited its range to the around the Albian – Cenomanian boundary. By contrast Calonge-Garcia (1996) and Bilotte (1998) restricted the species to the lower Cenomanian, and Velić (2007) to the upper Cenomanian.

Determining the range of this species is hampered by a lack of unequivocal illustrations in the literature coupled with a lack of independent age calibration. De Lapparent et al. (1974) provided an unillustrated record of P. parvus from Afghanistan and also points out the difficulties in establishing the difference between the Cenomanian and Turonian in sections devoid of ammonites. Upper Cenomanian records can be supported by the illustrated record from Croatia of Velić & Vlahović (1994), the illustrated occurrence from undifferentiated middle – upper Cenomanian of central Mexico by Omaña et al. (2013, 2014, 2019), and the illustrated record of Shahin & El Baz (2010, 2013) from Sinai. An additional illustrated record from southeast Mexico is that of Rosales-Dominguez et al. (1997) but their assessment that it is “post Cenomanian” in age is based partly on circular reasoning and is incorrect. The unusual Turonian record of Orabi & Khalil (2001) from Sinai is not substantiated by illustration.

Other than Chiocchini et al., (2012), late Albian and early Cenomanian records of the species lack substantiation by illustration but include Scott (2002) from Mexico; Calonge et al., (2002); Caus et al. (2009); Vicedo et al., (2011) and Consorti et al., (2016b) from Spain; Bachmann et al. (2003) from Sinai; and Ilavsky & Salaj (1969) from Tunisia. Although not illustrated, the middle Cenomanian record from Lebanon of Saint-Marc (1981) is important as the co-occurrence with the ammonite Calycoceras gentoni (Brongniart) supports a middle Cenomanian age calibration.

Cenomanian Paleogeographic Distribution

Caribbean – Neotethys (and? Afghanistan).

In addition to the records above, the species as been recorded from other parts of southern Italy ( Luperto-Sinni & Borgomano, 1989 (late Cenomanian); Borghi & Pignatti, 2006 (late Cenomanian); Di Stefano & Ruberti, 2000, all without illustration) and the Iranian Zagros ( Jamalpour et al., 2018 (illustrated), (but not Omidi et al., 2018; Mohajer et al., 2021a, 2022a, b).

The records from Greece ( Fleury, 1980 (also 1971, unillustrated) = possible Pseudorhapydionina sp. ) and Syria ( Ghanem & Kuss, 2013 = possible peneropolid, but not P. parvus ) have illustrations which are not compatible with this species, whilst those from southern Turkey ( Tasli et al., 2006; Sari et al., 2009) and southern Iraq ( Al-Salihi & Ibrahim, 2023) are tentative or unconfirmed by illustration.