MORPHOLOGICAL ASSESSMENT OF Pincerna globosa (H. ADAMS, 1871) FROM WESTERN SARAWAK (MALAYSIA BORNEO)

Pincerna globosa is known as the sole species of the genus Pincerna distributed in Sarawak. Our preliminary morphological assessment of P. globosa of different populations indicated variation based on their shell shape and size. Therefore, we aimed to determine the extent of morphological variation of P. globosa based on these two characters. A total of 283 adult P. globosa were collected at limestone clusters in Bau, Padawan, and Siburan. The specimens were collected from Bau, Padawan, and Siburan and deposited into the Zoological Museum UNIMAS, Universiti Malaysia Sarawak. Based on landmark analysis, there is a significant variation in the shell shape of P. globosa (p < 0.0001) with LM10, the highest point of the lip, and LM15, the external point of the lip at the left profile of the shell, as the most variable landmarks characters. Principal Component Analysis (PCA) based on geometric morphometrics shows a total variation of 37.22% by the first two principal components. Our study has shown that the highest point of the lip and the external point of the lip at the left profile of the shell varies among populations. Furthermore, we found that populations from the limestone cluster Padawan are the largest in terms of shell size compared to populations from Bau and Siburan. We conclude that there are significant variations in the shell shape and size of P. globosa from the western regions of Sarawak.