Terrestrial molluscs of Pemba Island, Zanzibar, Tanzania, and its status as an “oceanic” island

Abstract

Pemba is thought to have had a longer and/or stronger history of isolation than its better-known counterpart, Unguja. The extent to which the biota support this hypothesis of greater oceanicity have been debated. Here, Pemba’s terrestrial mollusc (“land-snail”) fauna is surveyed and reviewed for the first time. We find at best equivocal evidence for the following hallmarks of greater oceanicity: impoverishment, imbalance, and a high rate of endemism. At least 49 species are present, families are represented in typical proportions, and there are only between two and four island-endemic species - i.e. a 4% to 8% rate of endemism. For land-snails, isolation thus seems to have been short (Pleistocene) or, if longer, weak. Nevertheless, Pemba does host endemic and globally rare species. Forty-five percent of the species found, including most of these, is restricted to forest reserves, with Ngezi Forest Reserve particularly rich. A further 45% are able to tolerate the island’s woody cultivated habitats. One new snail species (Cyclophoridae: Cyathopoma) and one new slug species (Urocyclidae: Dendrolimax pro tem.) are described. New data and illustrations are provided for other taxa.

Coastal Subsistence, Maritime Trade, and the Colonization of Small Offshore Islands in Eastern African Prehistory

“…The archaeomalacological samples (analyzed by PF) were identified using a range of published sources (Abbott and Dance 1998;Carpenter and Niem 1998;Richmond 2011;Robin 2008Robin , 2011Rowson 2007;Rowson et al 2010) and the nomenclature standardized with reference to the World Register of Marine Species (WoRMS Editorial Board 2016). The Minimum Number of Individuals (MNI) was recorded based on a range of taxon-specific non-repetitive elements (following Harris et al 2015), in addition to noting the presence of taxa that did not retain diagnostic features necessary for inclusion in MNI counts.…”

Anatomy of predator snail Huttonella bicolor, an invasive species in Amazon rainforest, Brazil (Pulmonata, Streptaxidae)

“…However, some African and West Asian genera characteristically have a pupiform shell, such as Huttonella, Gulella andSinoennea Kobelt, 1904 (e.g., Jutting, 1961;Rowson et al, 2010). Even within these, H. bicolor appears to have an excessively elongated and narrow shell, almost turriform.…”

Characterising marine mollusc exploitation in the eastern African Iron Age: Archaeomalacological evidence from Unguja Ukuu and Fukuchani, Zanzibar

“…As a physical comparative reference collection was unavailable, all material was identified to the lowest possible taxonomic level using published guides (Abbott, 1989;Abbott and Dance, 1998;Bequaert, 1951;Carpenter and Niem, 1998;Richmond, 2011;Robin, 2008Robin, , 2011Rowson, 2007;Rowson et al, 2010;Spry, 1964Spry, , 1968. To avoid potential over-identification, those specimens that did not retain diagnostic features or morphological characteristics for species level attribution were assigned to the appropriate genus or family (e.g.…”