First population study of Caribitroides (Caribitroides) tuxtlensis (Amphipoda: Talitridae) from a rainforest in Veracruz state, eastern Mexico

Abstract

ABSTRACT The present study represents the first effort to analyse the growth, abundance, sex ratio, fecundity and population structure of the terrestrial amphipod Caribitroides (Caribitroides) tuxtlensis from the Santa Martha rainforest, Los Tuxtlas, Veracruz, eastern Mexico. The amphipods were collected using several necro traps during 2001 and were subsequently classified into juveniles, males, females and ovigerous females. The total length of each specimen was measured and each ovigerous female’s eggs were counted. Each individual’s growth and number of modal classes were obtained using Bhattacharya’s method and their growth parameters using the von Bertalanffy equation. A total of 777 specimens were counted, of which 58% were juveniles, 35% were females and 7% were males. A sex ratio of 4.89 females per male was estimated. Four modal classes were estimated based on analysing the length frequencies. The maximum lengths were 13.67 and 13.15 mm and the growth rates were 0.45 and 0.39 for females and males, respectively. The average fecundity was 3.32 ± 1.89 eggs, ranging from one egg in 6-mm females to nine eggs in 12-mm females. The survival rate was 53.69% for females and 38.33% for males. The high percentage of juveniles, the four age classes identified and the sizes obtained are consistent with other terrestrial amphipod species. Based on the number of eggs of reproductive females, this species can be classified within the low-fertility group of amphipods.