Plumatella pirassununga

Remarks. This species was previously known only from a lake on the campus of São Paulo University at Pirassununga, São Paulo State, Brazil (Wood & Okamura 2017). In the original description the colony ectocyst was described as “ well encrusted, giving it a velvety appearance ” (Wood & Okamura 2017). In the Amazon material the ectocyst was colorless and nearly transparent, but with distinct raphe and furrow. One feature of the floatoblast, shown but not emphasized in the original description, is the prominent polar groove at each end of the dorsal fenestra that is much wider than in most other plumatellids (Fig. 6 a). The slightly curved lateral profile of the floatoblast is shown in Fig. 6 b; the crenulated suture is easily seen in Fig. 6 c where it has a more serrated appearance. Floatoblast dimensions in Table 1 are consistent with those of the type material (Wood & Okamura 2017).

Material examined. NHMUK 2021.11. 23.22 from the Río Negro, municipality of Iranduba, 4 km SW of Manaus, Amazonas State, Brazil, 3 ° 9.956 ’ S, 60 ° 3.264 ’ W (Site 4), collected 5 May 2018 by T. Wood and B. Okamura. Colonies were attached to a disposable plastic plate.