Spaulding, S.,
Edlund, M.
(2008).
Platessa.
In Diatoms of North America.
Retrieved May 01, 2026, from https://diatoms.org/genera/platessa?x-craft-preview=409442409a997390693ff24c7010fd6f1c96fb56f8f091fa016a63de9a54aaccecpiqubknd
Monoraphid
Platessa
Frustules heterovalvar - one valve with a raphe, the other lacking a raphe
Valves nearly flat
Valves elliptic, linear-elliptic to elliptic-lanceolate
Striae mostly biseriate, sometimes uniseriate on raphe valve
Terminal raphe fissures absent
Frustules are heterovalvar, one valve possesses a raphe and the other valve lacks a raphe. Valves are elliptic, linear-elliptic or elliptic-lanceolate. Both of the valve faces are nearly flat, in contrast to other monoraphids that have convex and concave valve faces. Striae are mostly biseriate, but in some species the raphe valve face...