Metastoma
Abdominal plate present in some anthropods / From Wikipedia, the free encyclopedia
This article is about the abdominal plate present in some chelicerates. For the genus of land snail, see Metastoma roemeri.
The metastoma is a ventral single plate located in the opisthosoma of non-arachnid dekatriatan chelicerates such as eurypterids,[1] chasmataspidids[2] and the genus Houia.[3] The metastoma located between the base of 6th prosomal appendage pair and may had functioned as part of the animal's feeding structures. It most likely represented a fused appendage pair originated from somite 7 (first opisthosomal segment), thus homologous to the chilaria of horseshoe crab and 4th walking leg pair of sea spider.[2] In eurypterids, the plate was typically cordate (heart-shaped) in shape, though differed in shape in some genera, such as Megalograptus.[4]