Systematic study on Cypraeidae:
Does the protoconch give a clue to higher level relationships?
by Felix Lorenz
The question on how to separate between genera and subfamilies has been discussed before, mainly on the basis of features of the adult shell (Schilder & Schilder, L&H), the mantle (L&H), or the radula (Troschel, L&H, Bradner & Kay). The protoconch has been subject of a few studies (e.g. Ranson) but never has the microstructure been investigated in detail. In the following I am showing a few pictures of protoconch-groups in Cypraeidae, hoping that in the furture the features offered by this small detail in Cowries may aid to understand better how the various genera are related to each other.
1. Intracapsular ("Direct") development
Cypraeovula alfredensis: paucispiral protoconch of a direct developer
Cypraeovula algoensis algoensis: the similarities to other species in the genus are obvious
Cypraeovula edentula edentula: direct developing species appear to have a smooth, paucispiral protoconch
Zoila decipiens, albinistic specimen: In the Australian Zoila the similarities to the South African Cypraeovula are quite striking.
Zoila mariellae: Similar living conditions in the early state of development
have a common impact on the protoconch's shape.
Zoila perlae perlae: All Zoilae have very similar protoconchs.
Austrocypraea reevei: The same type of protoconch in another direct developer from
a group less related to the previous.
2. Planctonic Developement
Nesiocypraea teramachii
Nesiocypraea midwayensis: The two ancestral species from deep water have
a plurispiral protoconch with more than six coils, implying a long planctonic stage.
Erronea chinensis amiges: In the modern Erronea the protoconch has fewer whorls.
Purpuradusta minoridens
Purpuradusta fimbriata unifasciata: In the smaller groups the protoconch
is paucispiral, with a characteristic distinct microstructure
Bistolida kieneri depriesteri
Notadusta punctata berinii: The duration of the planctonic stage seems to be
rather short in these smaller Cypraeids.
Erosaria erosa
Erosaria helvola argella
Erosaria caputserpentis
Erosaria guttata azumai
Erosaria bernardi: All species of Erosaria have a similar type of protoconch, which
is faintly sculptured with longitudinal and transverse ridges of equal strength.
Poradusta surinamensis
Staphylaea nucleus: The protoconchs of Staphylaea and Proadusta are similar to those
of Erosaria, suggesting close relationship.
Ipsa childreni
Annepona mariae: Note the stronger longitudinal ridges in these two taxa.
Whereas the adult shells are very different, the protoconchs are
most similar and distinct from all other Cypraeids.
Finally, here is a rare picture of a Pediveliger of Erosaria labrolineata,
created by Scanning Electron Microscopy.
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