Schistoloma alta sibuyanica Bartsch, 1915

(Sinistral Specimen On The Left)

Sinistral Schistoloma alta sibuyanica Bartsch, 1915

Sinistrality in land prosobranchs (operculate land snails) is a rare and interesting phenomenon. It is a "normal" occurrence in about six lineages of the cyclophoroidean family Diplommatinidae L. Pfeiffer, 1858, and one species, Palaina taeniolata hyalina Quadras and Möllendorff, 1894 from Guam has somewhat indifferent chirality. In the H. G. Lee collection there are 240 dextral and 4617 sinistral specimens of this tiny oddity (just under 5% dextral mutants). See: Dextral Palaina taeniolata hyalina Quadras and Möllendorff, 1894

Records for mutant reversal of coil in the cyclophoroideans, to which Schistoloma Kobelt, 1902 [type: Cyclostoma alta G. B. Sowerby II, 1842] belongs, are reported in the table below (Dautzenberg; 1914, Nisters, 1999; Nunes and Santos, 2007; Gerber, 2009; taxonomy and nomenclature updated by H. G. Lee). As one can see, there are fifteen records from three families, Cyclophoridae Aciculidae, and Diplommatinidae, but Schistoloma Kobelt, 1902 is not in any of these three; it appears to be the first known instance of mutant reversal in the Pupinidae.

Also treated in the table is the other large group of terrestrial prosobranchs, the annulariid-pomatiid stock, which arose independently of the Cyclophoroidea and comprises the terrestrial radiation of the Littorinoidea. The land snails of this superfamily also seem disinclined to reversal of coil. In fact, until Dr. Gary Rosenberg recently found two sinistral specimens of Adamsiella irrorata in Jamaica, only a single instance of reversal  in the entire (dextral) family Annulariidae Henderson and Bartsch, 1920, which numbers about 700 species, was known (Jacobson and Boss, 1971; Watters, 2006). In the other littorinoidean landsnail group, the (dextral) Pomatiidae Newton, 1891, there is only one species known to exhibit reverse chirality (Dautzenberg, 1914).


Ditropis planorbis (Blanford, 1869) [Type of Ditropis Blanford, 1869 OD]
Neocyclotus prominulus (d'Orbigny, 1835)

Acicula letourneuxi (Bourguignat, 1864)
A. lineata lineata (Draparnaud, 1801)
A. lineolata banki Boeters, Gittenberger and Subai, 1989

Cochlostoma apricum (Mousson, 1847)
C. crassilabrum (Dupuy, 1851)
C. henricae henricae (Strobel, 1851)
C. hidalgoi (Crosse, 1864)
C. obscurum (Draparnaud, 1801)
C. patulum (Draparnaud, 1801)
C. septemspirale (Razoumowsky,
Diplommatina (Sinica) boettgeri Möllendorff, 1887
D. (Sinica) kiiensis Pilsbry, 1902
Nicida catathymia (Sykes, 1898)

Schistoloma (S.) alta sibuyanica Bartsch, 1915

Pomatias elegans (Müller, 1774)

Adamsiella irrorata Gloyne, 1875 <>
Cobolostylus jayanus (C. B. Adams, 1849)

Bartsch, P., 1915 The Philippine land shells of the genus Schistoloma Proc. U. S. N. M. 49(2104): 195-204 + 1 pl. (51).
Dautzenberg, P., 1914. XXIme assemblée générale annuelle (presidential address). Bulletin du Societé Zoologique de la France 34: 50-60.
Gerber, J., 2009. Personal communication 23 October. [Acicula lineolata banki]
Jacobson, M. K. and K. J. Boss, 1971. On a sinistral chondropomine from Jamaica. The Nautilus 84(4): 127-128. April.
Kobelt, W., 1902. Cyclophoridae bearbeitet. Friedländer und Sohn, Berlin. xxxix + pp. 1-662. July.
Nisters, H., 1999. Personal communication, 6 May 1999 14:49:34 PDT. Conch-L Archive 11496. [Acicula lineata lineata (second record) and Cochlostoma h. henricae]
Nunes, G. K. M., and S. B. dos Santos, 2007. A reversed coiled Neocyclotus prominulus (d'Orbigny) (Gastropods, Prosobranchia, Cyclophoridae) from Grande Island, Rio de Janeiro, Brazil. Revista Brasileira de Zoologia 24(1): 258-259. March.
Watters, G. T., 2006. The Caribbean Land Snail Family Annulariidae: A revision of the higher taxa and a catalog of the species. Backhuys, Leiden [viii] + 1-557 + 1 pl. + 8 pp. maps + 488 pp., 10 figs., 56 maps.