Ecology of an Indian grassland millipede Streptogonopus phipsoni (Diplopoda: Polydesmoidea)



Each of stadia II-VII and adults (stadia VIII) of Streptogonopus phipsoni (Pocock) can be distinguished by segment numbers, length, breadth and paired legs. Sexes are separate from stadium IV and sex ratios in immature stages were more or less 50% throughout the year, but high proportions of adult females are noted from June to September. High ratios of immature to adult were related to the breeding periods, from May to October, and in other months adults increased in proportion as a result of heavy mortality of immatures.

Adults were aggregated in distribution from April to October while solitary individuals were common in other months of the year.

Population density of S. phipsoni varied from 0.25 to 98 m-2 on the soil surface and 1 to 11.75 m-2 in the lower layer (0–7 cm deep). Biomass ranged from 12.25 to 2253 mg-2 on the surface and 50.75 to 424.75 mg-2 in the lower layer (0–7 cm deep).

A positive and significant correlation was found between mean monthly population density and mean monthly rainfall.

Streptogonopus phipsoni appears to complete its life cycle in one or two years