Figs. 2 a-b pars, 3-4

1948 Dictyoconella complanata n. gen., n. sp. – Henson, p. 25, plate 6, figs. 2-3, 16, pl. 10, fig. 14.

1986 Dictyoconella complanata Henson – Köylüoğlu, pl. 86, fig. 1 pars.

1998 Dictyoconella complanata Henson – Whittaker et al., pl. 47, figs. 4-6.

2016 Dictyoconus bakhtiari Schlagintweit et al. – Schlagintweit et al., fig. 8g, fig. 10f.

2020 Dictyoconella complanata Henson –Schlagintweit, p. 75, fig. 4d-f.

Description: See the genus description.

Dimensions:

Test diameter: up to 4.8 mm (3.3 mm, holotype specimen of Henson, 1948)

Test height: 3.6 mm (2.9 mm, holotype specimen of Henson, 1948)

Thickness: mostly between 0.8 and 0.9 mm (~ 0.8 mm, Henson, 1948)

Number of chambers last mm axial length: 7-9 (about 7, Henson, 1948)

Remarks: The dimorphism of D. complanata is well constrained by the biloculine embryo in the A-form and an indiscernible embryo within a close-coiled whorl including more chambers in the B-form (one section only, see Fig. 4b). The differences in the external test morphology between the two generations are unknown. In the family Orbitolinidae, B-specimens are generally larger and more flattened (e.g. Hofker, 1966). In the Iranian Tarbur Formation, D. complanata is comparably rare and only a couple of sections are available. Due to the revision presented herein, Dictyoconella becomes a monospecific genus and an assumed Maastrichtian newcomer that became extinct shortly afterwards at the K-Pg boundary. Besides the Tarbur Formation of Iran, D. complanata has been reported so far from the Maastrichtian Garzan Formation of southeastern Turkey (Köylüoğlu, 1986) revealing some kind of bioprovincialism, which requires subsequent study (Schlagintweit, 2020a).