Deviation of Dyar's rule in the post-embryonic development in millipedes - a comprehensive analysis.

Dyars value on the basis of length and width of nine polydesmid and 15 non-polydesmid millipede species were calculated. The value of polydesmid millipede ranged from 1.50 to 1.78 and that of non-polydesmid millipede ranged from 1.08 to 1.45. Weight progression factor was determined for nine species of millipede (two polydesmid and seven non-polydesmids). The result showed that the mean weight progression factor in polydesmid is 2.54 while that of non-polydesmid is 1.95. Both the results showed that Dyars value in polydesmida is significantly higher compared to that of non-polydesmida. In polydesmida, the number of stadium is only eight with higher Dyars value (mean 1.61) while in non-polydesmida, where number of stadium is more than eight have lower Dyars value (mean 1.23). As in other arthropods, Dyars value is inversely proportional to the number of stadium in millipede. The present study also affirmed Enders hypothesis in favour of adaptive importance of Dyars rule. Deviations from Dyars constant in these two group also support Crossbys growth rule. The variation of Dyars value in these two groups of millipede is related to the development time and habitat utilization. The variation of weight progression factor in these two groups is also linked to the development time as observed in other arthropods.