Pseudosonneratia

Description. According to Casey (1965), this more or less involute genus has a shallow umbilicus, subrectangular whorls, rounded umbilical and ventral margins, and flattened flanks that converge slightly towards a weakly convex venter. The primary ribs bear umbilical bullae that are only noticeable in juveniles. The secondaries unite with the primaries near the umbilical margin or are simply intercalated. All the ribs are sigmoid on the flanks and cross the venter, forming a proverse sinus. The sinus may be weakened in adults, mimicking Tetrahoplites. The umbilical bullae disappear over the body chamber, according to Destombes in Rat (1979). In fact, they are indistinct on almost all published specimens, chambered or not. The type species is Pseudosonneratia typica Spath, 1925, by original designation. On this site, we describe P. kalugini and P. iserensis, which are also typical of the genus. However, less typical specimens are found in the literature. For example, Destombes in Rat et al. (1979, pl. 4-8 and 4-9) shows some P. crassa without noticeable flattening of the ventral surface, and Casey (1965, pl. 90, fig. 1) illustrates a P. praedentata with distinct umbilical bullae despite its 85 mm diameter. He even specifies "20-22 elongated umbilical bullae" in his description.

Possible confusions. Tetrahoplites also has a rectangular whorl section but umbilical bullae persisting with age and a weaker ventral sinus. While T. subquadratus and orientalis are easily identifiable by their square section, the compressed forms can resemble Pseudosonneratia. For example, Casey (1965, p. 539) classifies Sonneratia rossica Sinzow, 1907, as Pseudosonneratia, whereas Saveliev (1992) assigns it to Tetrahoplites. Destombes in Rat et al. (1979, p. 86) confirms that some specimens are difficult to identify because they are intermediate between the two genera. Like Pseudosonneratia, Hoplites (Isohoplites) steinmanni in its adult stage (see its entry) has forked ribs crossing a more or less flattened venter. However, its ribs are curved forward instead of being sigmoid. Furthermore, it appears later in the Lower Albian.

Cooper and Owen (2011) add that the ribs of Pseudosonneratia have a cross-section without notable asymmetry, unlike the ribs with a steeper rear slope in Isohoplites, Tetrahoplites, and the Sonneratia of the dutempleana group. Saveliev (1992) emphasizes the existence of a temporary filiform groove on the siphonal line of Tetrahoplites, but Destombes et al. (1974) and Destombes in Rat (1979) report the same detail in Pseudonneratia. However, none of the Pseudosonneratia illustrated by Destombes shows this famous groove, whereas it is visible on several Tetrahoplites from Saveliev and in our collection (see our entry for T. suborientalis). These contradictions need to be clarified.

Distribution. This genus is found in Europe and Transcaspia, but it is uncommon. In Western Europe, it appears in the floridum zone and reaches its peak in the puzosianus zone of the Lower Albian. For Mangystau, Saveliev (1992) only mentions the puzosianus zone.

Genus Pseudosonneratia Spath, 1925

Suborder Ammonitina – Superfamily Hoplitaceae – Family Hoplitidae – Subfamily Sonneratiinae