Cyclostome Explained

Cyclostome is a biological term (from the Greek for "round mouth") used in a few different senses:

• for the taxon Cyclostomi, which comprises the extant jawless fishes: the hagfish (Myxini) and the lampreys (Petromyzontidae). This was thought for a time to be a paraphyletic group and this usage of the term was deprecated by some. However, there is strong molecular evidence for cyclostome monophyly,^[1] and thus the term remains in use.
• for the Order Cyclostomatida of bryozoans, tiny animals that live in colonies and form large calcitic skeletons.
• for one of two subgroups of braconid wasps.

Notes and References

1. Stock. David. Whitt GS. Evidence from 18S ribosomal RNA sequences that lampreys and hagfishes form a natural group. Science. 7 August 1992. 257. 5071. 10.1126/science.1496398. 1496398. 787–9.