Mastogloia is a genus of diatoms belonging to the family Mastogloiaceae.

[1] The genus has cosmopolitan distribution, primarily in marine waters.

[1][2] Members of this genus have complex silica chambers called partecta (singular partectum) along the sides of the first girdle band and are found only in the genus Mastogloia.

[3] Marine benthic diatoms of the genus Mastogloia are naviculoid (meaning they resemble diatoms of the genus Navicula) and symmetrical along the transapical axis.

[4][5] They prefer warm waters and are most commonly found in epipelic and epiphytic marine assemblages.