Diagnosis: Hendersonites with simple-ridged test wall and reduced costate ornamentation over the last one to two pairs of chambers.

Description: Test with chambers alternately added with respect to the test axis of growth resulting in biserial arrangement; tests consist of 10 to 16 chambers, which increase gradually in size and overlap at various rates. Chamber growth rate is moderate to high in most specimens, rarely lower in the adult stage; earlier chambers are subglobular, then subrectangular and crescentic in the adult and/or gerontic stages. The test is distinctly compressed in the terminal portion in some specimens resulting in a lanceolate edge view outline. Sutures are often indistinct between the earlier chambers of the test due to the heavy ornamentation and addition of successive layers of calcite; those between the chambers of the last two or three pairs are curved towards the anterior part and depressed. Test periphery with distinct test wall flexure lined by coarse costae, which form a rim-like structure around the test as seen in lateral view. Aperture is a low to medium high arch at the base of the last formed chamber; it is bordered by two symmetrically developed, small and rimmed periapertural flanges. There is a well-developed periapertural pustulose area on top of the chamber and above the aperture. Chamber surface is covered with costae, which are thicker over the earlier chambers and become gradually thinner over the last formed ones; juvenile specimens have costae with variable thickness (4.1–6.5 µm) over all chambers of the test; adult and gerontic specimens have thicker costae over the earlier chambers (7.8–8.5 µm) and those of the last formed chambers are much thinner (2.0–2.7 µm). Some of the thickest costae (6.8–7.5 µm) are developed in the peripheral region. Test wall is simple in juvenile specimens, with relatively small pores (1.1–1.9 µm) and simple-ridged with larger pores (3.2–4.2 µm) in the adult and gerontic individuals. Pores consistently occur between the peripheral costae, rarely disrupting them.

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