The Diplommatinidae of Fiji – a hotspot of Pacific land snail biodiversity (Caenogastropoda, Cyclophoroidea)

The minute (adult size 1.3-4.8 mm) land snail species of the family Diplommatinidae in the Fiji archipelago are revised based on historical material and modern (1998-99) collections targeting limestone outcrops on the largest island, Viti Levu, and several smaller islands in the Lau group. The forty-two species (including 30 new species) belong to the genera Moussonia Semper, 1865, Palaina Semper, 1865 and Diancta Martens, 1867, which are briefly characterized and keyed. The diagnostic structure of the inner lamellar system of each species is illustrated. All species except one are endemic to Fiji. In Viti Levu, the 12 localities surveyed each had 1-13 (average 5) species of Diplommatinidae; ten species were each found at a single site only. In the Lau islands, five islands were visited, with 1-4 species per island; four species are known from single islands. The number of historically known species not recollected in 1998-99 (7 species), the number of single-site occurrences (14 species), and the numerous islands - including limestone islands - that have not been surveyed at all, indicate that the 42 species of Diplommatinidae currently known from Fiji represent perhaps only half of the Fiji diplommatinid fauna. Such numbers approach the diplommatinid diversity of Palau (39 described and more than 60 undescribed species), and surpasses by far the diversity of other South Pacific archipelagos of comparable land area (New Caledonia, Vanuatu, Samoa). Nomenclatural acts: Lectotypes designated: Diplommatinafuscula, Diplommatinafusculavar.vitiana, Diplommatinagodeffroyana, Diplommatinagodeffroyanavar.latecostata, Diplommatinatuberosa, Diplommatinamartensivar.macrostoma, all Mousson, 1870. Neotypes designated: Diplommatinasubregularis, Diplommatinaascendens, Diplommatinaquadrata, all Mousson, 1870. New species: Dianctaaurea sp. n., Dianctaaurita sp. n., Dianctabasiplana sp. n., Dianctacontroversa sp. n., Dianctadensecostulata sp. n., Dianctadextra sp. n., Dianctadilatata sp. n., Dianctadistorta sp. n., Dianctapulchella sp. n., Dianctarotunda sp. n., Dianctasubquadrata sp. n., Dianctatrilamellata sp. n., Moussoniaacuta sp. n., Moussoniabarkeri sp. n., Moussoniabrodieae sp. n., Moussonialongipalatalis sp. n., Moussoniaminutissima sp. n., Moussoniaobesa sp. n., Moussoniapolita sp. n., Moussoniauncinata sp. n., Moussoniavitianoides sp. n., Palainaalberti sp. n., Palainaflammulata sp. n., Palainaglabella sp. n., Palainakitteli sp. n., Palainalabeosa sp. n., Palainaparietalis sp. n., Palainasulcata sp. n., Palainatruncata sp. n., Palainatuberosissima sp. n.