The family Provannidae was introduced by Waren & Ponder (1991). Including the genus described in the present paper, there are now four genera in the family, which can be distinguished according to the following key:

A. Large species (over 20 mm) with a furrow on the right side of the neck ..... B
A. Small species (below 15 mm) without furrow on neck ..... C
B. Shell Viviparus-like with smooth periostracum, sides of foot with large 'warts' ….. Ifremeria
B. Shell globular with bristly periostracum, side of foot with small rounded bulges only….. Alviniconcha
C. Shell melanioid, no pallial tentacle ….Desbruyeresia
C. Shell Buccinum-like, right pallial tentacle present …. Provanna

Two types of larval shells are known, one more resem¬bling a planktotrophic type, known in Desbruyeresia and Alviniconcha and one obviously lecithotrophic type in Provanna. The larval shell of Ifremeria is not known. The Alviniconcha-type larval shell closely resembles that known in Paleozoic species of Loxonematoidea (e.g. Hoare & Sturgeon 1985), and can be assumed to be a symplesiomorphy. The larval shell of Provanna is of a similar type, but drastically simplified, and the type may have evolved several times, through loss of planktotrophy. Known cases of such loss in other gastropods exhibit similar morphologic changes (see Waren & Bouchet 1990), that is, reduction of number of whorls and simplification of the sculpture.
The presence of a pallial tentacle in Provanna is shared with Abyssochrysos (family Abyssochrysidae), another Recent loxonematoid genus and can be considered a symplesiomorphy, while the absence of such a tentacle in the other genera of Provannidae cannot be used for comparisons.
The dorsal furrows on the head-foot of Ifremeria and Alviniconcha are similar, but since they are absent in Provanna and Desbruyeresia we do not know if they are homologous. A very similar furrow is known from some Cerithioidea (Houbrick 1987). The gonoduct is rather uniform among the Provannidae , but its anatomy is not known in the Abyssochrysidae. The strange position of the gonad in Ifremeria and Alviniconcha may be a synapomorphy. The hypertrophy of the gill may be another synapomorphy shared by Ifremeria and Alviniconcha, but it is a simple character, not to be relied heavily upon.
The radulae of the species within the genus Provanna cover the whole range of variation within the family. Provanna buccinoides and nassariformis have a radular type close to Ifremeria with membranous, densely packed teeth and a broad central tooth with reduced anterior supporting ridges. Most species of Provanna, including the type species, have a slender radula similar to Desbruyeresia with strong anterior supports on the central tooth. Alviniconcha has a broad radula, but well-developed anterior supports on the central tooth, intermediate between the average species of Provanna and Ifremeria. The radular morphology does therefore not help in grouping the genera.
The shells are of little use for classification. The shell of Alviniconcha is certainly, as discussed under the genus, a shell cheap to build and of comparatively small protective use. The shells of Provanna and Desbruyeresia are quite similar to each other, featureless and do not allow any conclusions. Ifremeria on the contrary has a rather complicated shell, especially the apical whorls, but that does not help since there is nothing to compare with, except some fossil species, currently classified in the Amberleyidae.
A more detailed investigation of the anatomy of Desbruyeresia and a similar undescribed genus (from non-vent habitats) is currently taking place and we want to postpone more detailed conclusions until that is finished.

Among the two Recent families of the Abyssochrysoidea , Provannidae and Abyssochrysidae, the following characters favour a position in the Provannidae:
—1. The shape of the foot. The propodium does not have the glandular corners equipped with tentacles, described by Houbrick(1979).
—2. The radular morphology is similar to Provanna. The main difference compared with Provanna is that the radula is proportionally broader and has lower teeth. Abyssochrysos has a much more robust radula.
—3. The species of Abyssochrysidae have a tall, slender shell, while the Provannidae have a much broader shell with a thick periostracum.
—4. The pallial gonoduct is principally similar in Provanna and Alviniconcha, although it is much more elongate in Alviniconcha, certainly a result of the longer pallial cavity.