Kalyptorhynchia is a suborder of rhabdocoel

flatworm Platyhelminthes (from the Greek language, Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") is a Phylum (biology), phylum of relatively simple bilaterian, Segmentation (biology), ...

s. It contains almost 600 species and has a cosmopolitan distribution.

Description

All kalyptorhynchs have an anterior muscular proboscis, which is used to capture prey. The proboscis is located inside an invagination of the epidermis called the proboscis-sheath that is closed by a sphincter at the tip of the body. Another

synapomorphy In phylogenetics, an apomorphy (or derived trait) is a novel Phenotypic trait, character or character state that has evolution, evolved from its ancestral form (or Plesiomorphy and symplesiomorphy, plesiomorphy). A synapomorphy is an apomorphy sh ...

supporting the group is the incorporation of the

axoneme In molecular biology, an axoneme, also called an axial filament, is the microtubule-based cytoskeletal structure that forms the core of a cilium or flagellum. Cilia and flagella are found on many cells, organisms, and microorganisms, to pr ...

s within the cell body of sperm cells during

spermiogenesis Spermiogenesis is the final stage of spermatogenesis, during which the spermatids develop into mature spermatozoon, spermatozoa. At the beginning of the stage, the spermatid is a more or less circular cell containing a cell nucleus, nucleus, Golg ...

Classification

Kalyptorhynchs are traditionally classified into two infraorders: Eukalyptorhynchia, with a cone-shaped proboscis, and Schizorhynchia, with a proboscis formed by two opposite parallel muscular sheets. However, molecular studies have shown that Eukalyptorhynchia, as originally defined, is paraphyletic and includes Schizorhynchia. It becomes monophyletic if the family Cicerinidae is excluded. Current phylogenetic classification:

References

{{Taxonbar, from=Q5017812 Rhabdocoela