Early Cretaceous large, few-chambered Globigerinelloides from the Tethys

New findings of well-preserved Early Cretaceous planktonic foraminiferal assemblages from the Cismon core (NE Italy), Calabianca (NW Sicily), Lesches en Diois (SE France) and DSDP Site 545 (off Morocco) sections allow a better understanding of the morphological features of several taxa. This paper deals with the revision of the small, planispiral individuals that several authors include in the genus Blowiella Krechmar and Gorbachik. Comparison of morphological characteristics between Blowiella and the genus Globigerinelloides Cushman and ten Dam has resulted in retention of the latter as senior synonym of Blowiella. In fact, the morphological differences (i.e. the number of chambers in the outer whorl, the width of the umbilical area, and size and spacing of pores) used to distinguish Blowiella from Globigerinelloides cannot, in our opinion, be used in discriminating genera, but can only be applied at species level. The small, few-chambered species of the genus Globigerinelloides retained here are Globigerinelloides blowi(Bolli), Globigerinelloides duboisi (Chevalier), Globigerinelloides maridalensis (Bolli), and Globigerinelloides paragottisi sp. nov. (=Globigerinelloides gottisi auctorum). Stratigraphically, in the sections studied Globigerinelloides blowi and Globigerinelloides paragottisi sp. nov. are first recorded from the mid-Upper Barremian in the Cismon core and Calabianca section, while rare individuals belonging to Globigerinelloides maridalensis and Globigerinelloide duboisi occur intermittently from the Barremian/Aptian boundary and from the Lower Aptian, respectively. All of these taxa become more frequent and abundant just above the Selli Level (OAE1a, Lower Aptian), within the Leupoldina cabri Zone (Upper Aptian). Based on the DSDP Site 545 succession, all four globigerinelloidid taxa range up to the Ticinella bejaouaensis Zone (uppermost Aptian), with Globigerinelloides maridalensis disappearing at the base of the zone, followed in close succession by the disappearance of G. blowi, G. paragottisi and finally G. duboisi.

Early Cretaceous planktonic foraminifera from the Tethys

Early Cretaceous planktonic foraminiferal assemblages include rare planispiral and pseudoplanispiral morphotypes with elongate chambers that BouDagher-Fadel et al. assigned to Schackoina or accommodated in the new genus Claviblowiella. New findings of well-preserved planktonic foraminiferal faunas from the Lesches en Diois (SE France) section, the Cismon core (NE Italy), the Calabianca (NW Sicily) section and the Upper Aptian of Deep Sea Drilling Project (DSDP) Site 545 drilled off Morocco, have allowed a better understanding of the morphological features of these rare, unevenly distributed taxa. Our data demonstrate that each small planispiral species with globular chambers has a corresponding "clavate" morphotype which (as the "normal" forms) exhibits a smooth, finely perforate wall. Consequently, the latter have been assigned here to the genus Globigerinelloides and treated as subspecies of the "non-clavate" taxa. The (clavate) subspecies belonging to the genus Globigerinelloides here retained are G. duboisi sigali Longoria, G. maridalensis elongatus subsp. nov., G. blowi lobatus subsp. nov. and G. paragottisi clavatus subsp. nov., while Globigerinelloides minai Obregòn de la Parra is not retained. In addition, a new genus, Pseudoschackoina, type species Planomalina saundersi Bolli (senior synonym of Hastigerinoides cepedai Obregòn de la Parra, has been formalised for individuals possessing elongate, pointed, laterally compressed chambers, bearing tubulospines arranged on a pseudoplanispiral (dysaxial) coiling mode. Stratigraphically, in the sections studied the first taxon to appear is Pseudoschackoina saundersi, in the uppermost part of the Selli Level (=OAE1a), immediately followed, just above the OAE1a, by all the "clavate" globigerinelloidids. Regarding the last occurrences, Pseudoschackoina saundersi and G. maridalensis elongatus disappear in the lower part of the Globigerinelloides algerianus Zone, Globigerinelloides paragottisi clavatus at the top of the same zone, while Globigerinelloides blowi lobatus and G. duboisi sigali range up to the lower part of the Ticinella bejaouaensis Zone.