Type species: R. adamsi Morgan & Heppell, 1981. Anterior and posterior lateral teeth in the right valve only.
This subgenus has caused much confusion in the literature because it has been based on a misidentified type, which is an undescribed species. J. Adams (1861) described a subgenus Rhinomya to accommodate a species R. rugata Adams and, what he erroneously considered to be a previously described species, C. philippinensis Hinds (1843). The latter he named as the type, the subgenus being characterized by the possession of anterior and posterior lateral hinge teeth in the right valve. Smith (1885), dividing the Challenger cuspidariids into lettered sections, overlooked the name Rhinomya but recognized that the Adams specimen referred to as C. philippinensis was different from C. philippinensis Hinds. These he placed in different sections (G and H respectively), the former characterized by the posses¬sion of an anterior and posterior lateral tooth in the right valve, the latter by a single cardinal in the right valve. Instead of describing the Adams specimen and renaming it, Smith (1885) merely changed the authority, i.e. C. philippinensis Adams (nec Hinds).
Dall (1886) compounded the error by erecting a section Rhinoclama of the subgenus Leiomya, to encompass Rhinomya Adams and sections G and F (Smith 1885), naming N. philippinensis (A. Adams) Smith as the type. Later Dall (1890) established another subgenus Luzonia characterized by the possession of a single anterior cardinal tooth, rightly using the original species, C. philippinensis Hinds, as the type. Thus two subgenera with very different hinge types were listed based on types with the same name but with different authority.
Since then Prashad (1932) has described Rhinoclama as a subgenus of Cuspidaria, while Johnson (1934) considers it a section of the genus Leiomya. Thiele (1935) mistakenly states that the subgenus of Rhinoclama has no teeth at all and, to avoid confusion between the types of the two subgenera Rhinoclama and Luzonia, changes the name C. philippinensis Adams {nec Hinds) to C. adamsi Thiele. Unfortunately this name is invalid because it refers to a nomen nudum. Smith (1885) wrongly credits it to Adams. Nordsieck (1969) also perpetuates the error by following Thiele (1935). Moore (1969) follows Thiele's definition of Rhinoclama as being edentulous, but reverts to using C. philippinensis Hinds as the type.
The type specimen C. philippinensis Hinds of the subgenus Luzonia (B.M.N.H. (British Museum (Natural History)) no. 1961 122) has an anterior cardinal tooth in the right valve. There is another specimen (B.M.N.H. no. 1.28.416.1878) labelled 'Rhinomya A. A. philippinensis Hinds; Location Uraga', which is almost certainly the specimen referred to as R. philippinensis Hinds by Adams (1864), and that Thiele (1935) renamed C. adamsi. It comes from the same location as that which Adams described, and the specimen is part of the Adams collection bought by a Mr Geale, and later given to the British Museum (Natural History). It has a single anterior and posterior lateral tooth in the right valve.
Powell (1937) described a new genus Austroneaera to accommodate Australian species with an anterior and posterior lateral tooth in the right valve only. From the description, there appears to be no difference between this and Rhinoclama, and we therefore synonymizc Austroneaera with the subgenus Rhinoclama.