The following from Vinyard, 1979: "Cells solitary, in flat filaments or in zigzag chains. Valves elliptical or triangular with markedly undulating sides; with transverse septa within cells extending across the short axis. Girdle view with septa perpendicular to valve face extending inward to level of intercalary bands; internal margin of each septum thickened and bent at an angle to the other portion strongly suggesting a series of musical notes".
The genus name Terpsinoe is derived from the Greek word "terpsinoos", meaning “delight, heart gladdening” (Vinyard, 1979). The species name “americana” originates from the Latin adjective, meaning “of or pertaining to America” (Guiry & Guiry, 2010).
T. americana is considered a centric diatom.
In the United States, this centric species has been found in the Hudson River, Rockaway, Long Island, Charleston, S.C., St. Augustine, FL (Boyer, 1927) and the San Francisco Bay (Laws, 1988). It also occurs in the Gulf of Mexico (Felder and Camp, 2009), specifically in Tampa Bay, Pensicola Bay, and Punta Gorda, Florida (Mohr, 1901; US Nat. Herb. collection database, 2010) and Mobile Bay, Alabama (Cox, 1885).
Outside North America, it occurs in Hangalore, India (US Nat. Herb. collection database, 2010), the marine littoral of Mauritania (Sterrenburg, 1994) and in southern Iraq (Pankow et al, 1979). T. americana is present in the fossil record off the Polish coast, in the Baltic Sea (Kaszubowski, 1992).
T. americana (Bailey) Ralfs occurs in brackish and freshwater, while the genus as a whole is usually considered to be marine (Kirk & Smeins, 1976; Vinyard, 1979; Boyer, 1927). It occupies the same habitat as T. musica, but has a preference for saltier conditions (Sterrenburg, 1994).
El-Kheir & Mekkey (1986) reported that this species Inhabits brackish or marine lakes and springs in Egypt. It has also been observed in the marine littoral zones off the subtropical coast of South Africa (Cholnoky, 1968) and Mauritania (Sterrenburg, 1994).
T. americana is distinguished from T. musica by its smaller size, absence of a central spine, fewer septa (4), and lack of capitate endings characteristic of T. musica (Peragallo & Peragallo, 1896).
Frustules quadrangular, with septa extending about half way into the valve. Valves with undulating outline (Boyer, 1927), lobed at each end or angle (Boyer, 1927; Boyer, 1916) and inflated in the middle, divided by septa into three or more segments. Central space rounded, hyaline (Boyer, 1916). Surface with coarse but indistinct puncta (Boyer, 1927) or fine puncta in radiating lines (Boyer, 1916), about 6 in 10, µ. L. of v. 58 µ. (Boyer, 1927). Labiate process absent (Sterrenburg, 1994).
