Several names share this combination and are defined under the rules of the botanical code. The species name Sphacelaria caespitula might be an homonymy case.
The name Sphacelaria caespitula is a slight homonymy case. This name is used according to the rules of several different nomenclatural codes.

Sphacelaria caespitula Lyngb.

Botany

Sphacelaria caespitula Ag.

Botany

Sphacelaria caespitula Grev.

Botany

Sphacelaria caespitula Lyngb.

Zoology