The family Clavatoridae was historically treated as a family within the superfamily Acavoidea due to morphological similarities.
Johannes Thiele (1931) considered that the Stirps Acavacea (informal historical grouping) contained six families:[9]
Thiele's Clavatoridae were placed into the Acavidae s.s. following the studies of Kenneth C. Emberton (1995) who demonstrated with cladistic analysis that different groups of Clavator are embedded in Helicophanta s.l.. Emberton's results of phylogenetic analysis were applied to systematic concept and altered the nomenclature according to findings and conchological approach.[9]
Emberton regarded the genus Clavator as being paraphyletic. It comprises a minimum of three species-groups, which share conchological, as well as ecological and zoogeographical characteristics.[9]
Subsequently, he placed them here in 3 conchologically well defined genera and subgenera:
- Clavator - s.s.
- Clavator (Cylindroclavator) - n. subgen.
- Paraclavator - n. gen.
However, molecular phylogenetic analyses using mitochondrial and DNA markers have demonstrated that Clavator and aligned genera constitute a monophyletic clade that is phylogenetically distinct from Acavidae due to their unique shell characteristics, reproductive anatomy and geographic distribution.
This view was revised by Anatoly Alexeevich Schileyko (1999), who elevated Clavatoridae again to family status based on detailed anatomical differences, especially in reproductive structures.[5]
The genera Clavator and Paraclavator showed a conchological resemblance to the southern American genus Obeliscus Beck, 1837 of the family Subulinidae. As a consequence, the name "Obeliscus" was used in error for these Malagasy molluscs.[9]
Collections made in 2007 were intended to be used to initiate phylogenetic and biogeographic studies on Madagascan acavids, to be based primarily on DNA sequences and genital anatomies, therefore Paraclavator is currently listed (previously classified in Acavidae, but currently placed in Clavatoridae).[10]
Leucotaenius, originally described by Eduard Von Martens in 1860, was also initially placed in the families Acavidae or Achatinidae based on conchological features such as its large, elongate shell.
However, subsequent anatomical investigations, particularly those by Schileyko (1999), revealed that Leucotaenius shares key reproductive and jaw characteristics with the genera Clavator and Paraclavator.[5]
The new species described in the book bring Madagascar’s total described rhytidoids to 135 species:[5]
The current following classification was subsequently adopted by Bouchet et al. (2017) published in Malacologia:[14][15]
Clavatoridae does not have any recognized subfamilies.
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