Dictyoconella Henson, 1948, Upper Cretaceous Larger Benthic Foraminifera: A Taxonomic Revision With The Establishment Of Gusicella Gen. Nov. (Type-Species Dictyoconella Minima Henson) Author SCHLAGINTWEIT, FELIX Author RASHIDI, KOOROSH text Acta Palaeontologica Romaniae 2021 2021-02-17 17 2 3 13 http://dx.doi.org/10.35463/j.apr.2021.02.01 journal article 10.35463/j.apr.2021.02.01 1842-371x 12583322 Dictyoconella complanata Henson, 1948 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 ) Fig. 7 Gusicella minima (Henson) gen. et comb. nov. from the late Maastrichtian of the Tarbur Formation, SW Iran (Mandegan section: b, l ; Naghan section: a, c–k ). a Oblique transverse section. b Oblique section cutting the marginal (upper part) and central zones (lower part) displaying irregularly distributed fused pillars/secondary deposits. c, k Subaxial sections. d–g, Axial sections showing initial spire. h–i Details (from e and g ) of the initial spire. j Tangential section. Slightly oblique transverse sections showing subdivision of the marginal zone and circle of marginal apertures (left and above). Abbreviations: m.f. = marginal foramen, m.t. = marginal trough, pr = protoconch, s.d. = secondary deposits/fused pillars. Thin sections: 2Ng 17 ( a, k ), Rt 100 ( b ), Ng 180-1 ( c ), 2Ng 179-1 ( d ), 2Ng 168 ( e, h ), 2Ng 175 ( f ), 2Ng 174 ( g, i ), 2Ng 177 ( j ), Rt 113 ( l ). Fig. 8 Gusicella minima (Henson) gen. et comb. nov. from the late Maastrichtian of the Tarbur Formation, SW Iran (Naghan section: a–b, j, l ; Mandegan section: c–i, k, m–p ). a Subaxial section. b, i, l Oblique sections. c–e, m Deep tangential sections displaying primary septules (beams) continuous (aligned) from one chamber to the next. f Shallow tangential section displaying subepidermal network of beams and rafters. g, j, l, o–p Different transverse sections, some slightly oblique. Note five marginal foramina arranged in a radial circle (inside yellow marked rectangle in o ). Note oval test outline in j. Subaxial section. Note alternation of pillars by stairway-like arrangement of foramina (yellow line) and opaque fused pillars/secondary deposits in the central zone. k Detail from h showing marginal foramina arranged in vertical lines between successive chambers. n Tangential-oblique section. Abbreviations: b = beam, ib = intercalary beam, f = foramen, m.f. = marginal foramen, m.t. = marginal through, pi = pillar, s = septum. Thin sections: Ng 196 ( a ), Ng 192 ( b ), Rt 108-3 ( c–e, g, n ), Rt 104 ( f ), Rt 96 ( h, k ), Rt 108-6 ( i ), Ng 187 ( j ), Ng 186 ( l ), Rt 107 ( m ), Rt 102-2 ( o ), Rt 104 ( p ). 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 ).