Porosia paracarinata Bobrov & Kosakyan, 2015

Diagnosis: Shell large, pyriform, laterally compressed, with a rounded posterior part, narrow elliptical in profile. At approximately 1/3 of test length starting from the aperture, two distinct lateral depressions with two large invaginated pores are situated on each side, which are connected by internal tubes as in Porosia bigibbosa. In profile, small lateral pores can be observed, just anterior to the large pores. At approximately after 1/2 of the length of the test counted from the aperture, a lateral keel emerges such as in Planocarina (Nebela) carinata, the width of which can vary between individuals. Shell colorless, composed of circular or elliptic or irregular plates, often covered by a thin layer of organic cement. Aperture oval, curved, surrounded by a thick organic lip.

Dimensions: According to Bobrov and Kosakyan (2015): Shell length 202—236 µm; width 142—157 µm; aperture 56—67 µm wide.

Habitat: In wet leaves (forest litter) in a mixed forest of Fagus sp. and Cider japonica, Japan. In 2019 it was found in India by Dr. Bindu Shaji (pers. comm.).

Geographical distribution: Japan, India.

Remarks: Morphometric analyses of Porosia paracarinata show that species is characterized by low variability. The largest standard deviation (SD) was observed in test length. The most stable morphological character is the thickness of the organic lip surrounding the aperture. The width of the lateral keel can also be variable among the individuals starting from very narrow (3.75 µm) to very wide (13.13 µm).

References: Bobrov, A. and Kosakyan, A., 2015: A New Species from Mountain Forest Soils in Japan: Porosia paracarinata sp. nov., and Taxonomic Concept of the Genus Porosia Jung, 1942 – Acta Protozool. 54: 289-294.