A new genus and new species of the family Darcythompsoniidae Lang (1936), a
nd a new record of Darcythompsonia fairliensis (T. Scott, 1899), from a coa
stal lagoon in the south-eastern Gulf of California (Mexico), are reported
and fully described and illustrated. Pabellonia olganoguerae gen. nov., sp.
nov. shares features with Darcythompsonia T. Scott, 1906, such as the prese
nce of a dimorphic second endopodal segment of the male second swimming leg
, and with Kristensenia Por, 1983, the lack of sexual dimorphism in the cau
dal rami, anal operculum and urosomites. Thus it is considered closely rela
ted to these genera, and to represent a third component of this lineage. So
me notes on the biogeography of Darcythompsonia T. Scott, 1906, are also pr
esented. (C) 2000 The Linnean Society of London.