Sex Ratio and Carapace Length-Width Relationship of Pilumnid Crab, Heteropanope glabra Stimpson, 1858 (Brachyura: Pilumnidae)

Some aspects on biology of pilumnid crabs, Heteropanope glabra Stimpson, 1858 were studied.  Crabs were collected from mangrove area near the paved road along the seashore bridge, Muang district, Chonburi province.  Specimen of crabs were collected for two months from April to May 2016.  The total number of collected crabs were 444 crabs, with 217 males and 227 females.  Female crabs were divided into two groups, without egg and with eggs.  There were 95 females without egg and 132 females with eggs.  The sex ratio between male and female crabs was 1.05: 1.00.   The carapace width in most of the male crabs were in the range of 12-22 mm, whereas in female and ovigerous female crabs were in the range of 12-17 mm.  The maximum and minimum carapace width of male crabs was 25.28 and 8.29 mm respectively, with the average of 16.28 ± 2.60 mm.  The maximum and minimum carapace width of female crabs without egg were 18.18 and 10.97 mm respectively, with the average of 14.25 ± 1.59 mm.  The maximum and minimum carapace width of female with eggs were 18.98 and 9.72 mm, respectively with the average of 14.05 ± 1.67.  There was no difference between average size of female without eggs and females with eggs.  The carapace width of the smallest size of female crab with eggs was 9.72 mm.  The equation of the relationship between carapace width and carapace length of crabs in both sexes was    CL = 0.6469CW + 0.7309  Keywords : sex ratio, carapace width, carapace length, Pilumnid crab, Heteropanope glabra 309