Lyrischapa Aldrich, 1911

Merle, Didier, Pacaud, Jean-Michel, Métais, Grégoire, Bartolini, Annachiara, Lashari, Rafiq A., Brohi, Imdad A., Solangi, Sarfraz H., Marivaux, Laurent & Welcomme, Jean-Loup, 2014, Volutidae (Mollusca: Gastropoda) of the Lakhra Formation (Earliest Eocene, Sindh, Pakistan): systematics, biostratigraphy and paleobiogeography, Zootaxa 3826 (1), pp. 101-138 : 111

Genus Lyrischapa Aldrich, 1911

Type species. Lyrischapa harrisi Aldrich, 1911 (Middle Eocene, Mississippi, USA) by original designation.

Discussion. Wenz (1943) assigned Diconomorpha Wenz, 1943 [type species Diploconus elegans Douvillé, 1929 = Diploconus Douvillé, 1929 , non Candèze (1860) [Insecta] by original designation] to the Pholidotominae Cossmann, 1896, but Volutocristata Gardner and Bowles, 1934 [type species: V. chiapasensis Gardner, 1934 by original designation] and Lyrischapa to the Volutinae , in spite of close similarities between these three genera. Givens (1979) demonstrated that Volutocristata is a junior synonym of Lyrischapa and, following Pilsbry & Olsson (1954), he assigned Lyrischapa to the Fulgorariinae , because of the deviated protoconch, numerous columellar folds, a shallow siphonal notch and a weak siphonal fasciole. Later, Givens (1991) suggested that Diconomorpha might be a junior synonym of Lyrischapa . In addition, he considered that the assignment of Lyrischapa to the Fulgorariinae is incorrect, because members of this subfamily are distinguished from Lyrischapa by quite different shapes (fusiform to ovate), absence of an anal sulcus on the outer lip, and generally fewer columellar folds. Species of Lyrischapa have a biconic shape, a spiral row of variably developed shoulder spines, weak spiral sculpture on the last whorl, and five to six strong columellar folds. Several Athletinae and particularly the genus Athleta share with Lyrischapa a biconic shape and a row of shoulder spines. For this reason, Vredenburg (1923) compared his new species A. blanfordi with Athleta (Athleta) . However, the early whorls of Athleta (Athleta) species display a subsutural and two abapical rows of nodules, which are missing in Lyrischapa . This character is widespread in juveniles of Athleta species and is even present in adults of A. ( Volutocorbis ) species. Thus, the similarities between the shells of Athleta and Lyrischapa are superficial. The shells of Lyrischapa more closely resemble species of the Amoriinae or the Volutinae . In the Amoriinae , they can be compared with Nannamoria Iredale, 1929 [type species: N. amicula Iredale, 1929 ]. Several species (e.g. N. ralphi (Finlay, 1930) from the Middle Miocene of Australia or N. paraboloides Darragh, 1988 from the Late Neogene of Australia) have a biconic Athleta shape, developed shoulder spines and weak spiral sculpture on the last whorl, but differ from Lyrischapa by the presence of only four strong columellar folds (instead of five or six to eight). With respect to the Volutinae , the shells of Lyrischapa can be compared with Voluta ebraea Linnaeus, 1758 or V. m u s i c a Linnaeus, 1758 (Recent, Brazil), which exhibit five to six strong columellar folds and several weaker folds adapically, and some specimens have a biconic shape with developed shoulder spines. However, a morphological type close to Lyrischapa is uncommon in the Amoriinae and Volutinae and could be the result of convergent and repeated evolution. Thus, like Givens (1991), we conclude that the subfamilial position of this genus is uncertain, but we believe that an assignment to the Fulgorariinae or Athletinae is incorrect.