Species Description: Valves only slightly or not sigmoid, broadly lancolate with slightly rostrate apices. The raphe is somewhat sigmoid (Fig. 1, entire valve exterior, SEM) and sharply hooked at the apices (Fig. 3, detail of Fig. 1), with the central raphe endings highly variable, according to Sterrenburg (2001), but seen here somewhat deflected to opposite margins and not overlapping (Fig. 2, detail of Fig. 1). In contrast to most species of Pleurosigma, the external foramina of the areolae are circular rather than slit-like (Fig. 2)
The cells are recorded as 55-90µm long, 1-22µm wide, with 25-27 transverse and 18-22 oblique striae in 10µm, crossing at about 60 degrees. The species is known from the Caribbean Sea, Pacific Ocean, Indonesia, and coast of Kenya (Sterrenburg 2001). It is rare in the IRL system, found only once near the Fort Pierce Inlet (Fig. 1): slightly smaller than elsewhere, measuring 51.5 X 13µm with 25 transverse and 22 oblique striae in 10µm, crossing at about 62 degrees.
Sterrenburg FAS. 2001. Studies on the genera Pleurosigma and Gyrosigma: The types of Shadbolt and related taxa. Proc Acad Nat Sci Philadelphia 151: 121-127.