Species diversity and population ecology of giant pill millipedes family zephroniidae in Nan province

Abstract

This study focused on species diversity and ecology of the giant pill-millipedes family Zephroniidae in Nan Province. The millipedes were collected in rainy seasons of 2009-2011 for species diversity study. Two genera of the giant pill-millipedes; genus Sphaerobelum Verhoeff, 1924 and genus Zephronia Gray, 1832 of family Zephroniidae were dominated in this area. Genus Sphaerobelum occupied in higher moisture habitat such as moist deciduous forest and evergreen forest, while genus Zephronia presented in mixed deciduous forest and dry deciduous dipterocarp forest. Population ecology such as population size, dispersion, daily activities, diet and growth of the giant pill-millipedes, Zephronia cf. viridescens, from Chulalongkorn University Forestry and Research Station, Wiang Sa District, Nan Province was studied. Population size and dispersion were studied during 2009. Twenty of 2x2 m2 quadrats were sampling randomly each month for one year. For daily activities study, the data of each millipede sample were recorded every 30 minutes throughout the day. The result showed that they spent most of the time under leaf litter for feeding and another major activity tended to be mating at nighttime. Diets of the giant pill millipedes were observed in the habitat. Parts of plants and litter being consumed by them were collected and it was found that the major food items were Gigantochloa albociliata and Bauhinia spp. Growth was observed and recorded in enclosures within the habitat during 2009-2011. The data showed that hatchlings had to pass through eight moltings before having a constant number of segments and small millipedes molted more frequently than the larger sizes. From all information, the life span of Z. cf. viridescens was estimated to be more than 5 years. Differences in morphology between sexes were measured and compared. The dominant morphological characters of males were thoracic shield, ninth, tenth, eleventh and twelfth body segments, anal shield and sensorial cone number of the antennae. Most of their ecological data represented the adaptation of Z. cf. viridescens for survival and reproduction within the habitat.