Terrestrial molluscs species richness and diversity in Gashaka - Gumti National Park, Taraba State, Nigeria.

Abstract

To assess the biodiversity of terrestrial molluscs in Gashaka-Gumti National Park, a four plot (20 x 20m) each within the park were sampled by searching the forest floor, tree trunk, fallen logs, root facies, and vegetation for the presence of mollusks. The species found were collected by hand picking.A total of 819 specimens comprising 22 species belonging to six molluscan families were collected from four plots. Each plot yielded between 8 to14 species (Mean:10, Standard Deviation:2.71) and 33 to 683 individuals (Mean:204.75, Standard Deviation :319.09). The most abundant species in the park was Curvella sp. represented by 683 individuals (79.4%) of the total sampled species. The most abundant family is Streptaxidae represented by 8 species (36.4%) of the total sample.The sample intensity was 37.22 while the Inventory Completeness is 79.31%. Eleven (11) species occurred as singleton across plots while ten (10) species occurred as doubleton across the four plots sampled.The Whittaker Index is 4.00. The rarefaction curve nearly reached an asymptote as sampling stopped. The nonparametric estimator Chao 2 and jackknife 2 were 28.05 and 33.99 of all sample collected. The dendogram of similarity by plots using Bray-Curtis similarity of index show the close relationship of two plots in terms of species. It shows that there is no significant difference between plots. Plot 1 and 4(P=0.4329), Plot 2 and 3 (P=0.9595), Plot 1 and 3 (P=0.2390), Plot 2 and 4 (P= 0.78). In conclusion, the family Subulinidae has the most abundant individuals with 733 individuals representing 89.4% while Streptaxidae occur as the most abundant family with 8 species of the total sample.