''Tetrorchis'' is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus of deep-sea

hydrozoan Hydrozoa (hydrozoans; from Ancient Greek ('; "water") and ('; "animals")) is a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline water. The colonies of the colonial sp ...

in the family

Rhopalonematidae Rhopalonematidae is a family of hydrozoans Hydrozoa (hydrozoans; from Ancient Greek ('; "water") and ('; "animals")) is a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit ...

. It is represented by the species ''Tetrorchis erythrogaster''.

References

Rhopalonematidae Taxa described in 1909 {{hydrozoa-stub