Population Dynamics of Geosesarma sp: A New Species of Vampire Crab from the Menoreh Mountains of Java, Indonesia

This research provides new records of the Geosesarma sp.population dynamics in the Meneoreh Mountains, Kulon Progo, Indonesia, since this crab was first discovered.This research aims to find out the latest information about population dynamics, which includes size distribution and sex ratio, growth patterns through the relationship between carapace width (CW) and body weight (BW), recruitment patterns, growth performance, and mortality of Geosesarma sp.The research was carried out from June 2023 to May 2024.The research location is in the Menoreh Mountains (07 o 44.874'LS, 110 o 08.066'E) which is divided into three stations.The results showed that the sex ratio of the three stations was 1:0.4,1:0.58, 1:0.6;The size distribution of males is more dominant than females, where at Station 1 the male CW size ranges from 9.7-11mm, and 6.9-8.2mm for females, Station 2 ranges from 8.9-9.7mm,Station 3 shows the CW is 7.5-8.4mm,and 6.5-7.4mm.The CW-BW relationship shows that the growth pattern of male crabs is positive allometric (b > 3), and that of female crabs is isometric.The growth coefficient shows a slow growth pattern (K<2).Station 1 showed that male experienced peak recruitment in July (18.56%), while females experienced peak recruitment in October (20.13%); at Station 2 in June (17, 34%) and May (20.38%); while station 3 in May was 16.89% and 24.06%.Crab mortality is caused by natural death and minimal fishing exploitation.