Costia necatrix vs costia

Costia necatrix and costia both are nouns.

Word	Noun	Adjective	Verb	Adverb
Costia necatrix	Yes	No	No	No
costia	Yes	No	No	No

As nouns, Costia necatrix and costia are synonyms defined as:

Costia necatrix and costia: a flagellate that is the cause of the frequently fatal fish disease costiasis

Costia necatrix (noun)	costia (noun)
a flagellate that is the cause of the frequently fatal fish disease costiasis	a flagellate that is the cause of the frequently fatal fish disease costiasis