Compare Mastogloia binotata

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If the valvocopula is attached, this taxon is easily recognized and distinguished from all other members of the Ellipticae morphological group because of the single partectum centrally located on each side of the valvocopula. If the valvocopula is not attached, valves may resemble other elliptic diatoms within the genus, such as Mastogloia cribrosa, but also some species of Cocconeis.

Mastogloia cribrosa has a more circular valve outline, has more widely separated areolae, and lacks a fascia. The narrow lanceolate fascia is particularly helpful in narrowing possible species determinations. Mastogloia crucicula also exhibits a narrow lanceolate fascia, but its valve outline is more narrow elliptic.

Mastogloia crucicula var. alternans has two bilobed partecta located in opposite quadrants of the valvocopula.

Cocconeis dirupta and C. pseudodiruptoides have similarly coarsely punctate elliptic valves with a lanceolate stauros, however both of these Cocconeis species have sigmoid raphes.