Externally measured condition versus internal organ mass in the caecilian Gegeneophis ramaswamii (Amphibia: Gymnophiona: Caeciliidae).

The relationship between externally measured condition (mass x length(-3)) and the mass of internal major organs in the caecilian Gegeneophis ramaswamii is investigated, based on a collection of 67 specimens from three southern Indian localities in the early and mid-monsoon. Condition in juveniles (< 90 mm total length) is higher than in subadults (90-170 mm) and adults (> 170 mm). The relationship between condition and total length is consistent in subadults, but variable in adults, and these differences indicate that the delimitation of these ontogenetic stages has some biological meaning. Adult females have fat bodies which fluctuate in mass, but not in relation to their body size. On average, adult females have heavier fat bodies and lighter gut contents than adult males, but there are no significant differences between subadult males and females. Gravid females are predicted to have a notably greater condition. There is no consistent relationship between condition and any major internal organ, but there is some significant variation among samples grouped by sampling time and locality. More sampling throughout the year is required to clarify the complex relationships between condition and internal organs, and before externally measured condition from ecological studies of living animals can be readily interpreted. However, its utility in helping to differentiate between ontogenic classes may be of immediate use.