Demographic and Reproductive Characteristics of a Southern Illinois Population of the Crayfish Frog, Rana areolata

Demographic (snout-vent length, skeletochronologically estimated age) and reproductive (fecundity, ova size) characteristics were examined in Riina areolata from Williamson County, Illinois. Fifty-nine frogs (36 males, 23 females) were sampled from breeding choruses in March 1996. Hematoxylinophilic annular lines of arrested growth (LAG) were detected in the diaphyses of cross-sectioned phalanges of all sampled frogs. t-tests revealed that male age (mean = 3.53 yr) and female age (mean = 3.83 yr) were not significantly different, but male SVL (mean = 82.78 mm) was significantly smaller than that of females (mean = 89.61 mm). There were positive correlations between SVL and age for both males (r2 = 0.66) and females (r2 = 0.58), with males maturing earlier than females. Eggs from 15 clutches (12 ovarian ova complements from dissected females; three clutches oviposited in the lab) were counted, and mean clutch size was 4868 ova. There were positive correlations between female SVL and clutch size (r2 = 0.76) and between female age and clutch size (r2 = 0.41). Mean ovum/embryo diameter for all yolked ovarian complements, and two oviposited clutches (preserved at the blastula stage or earlier), was 2.05 mm. Clutch size was inversely correlated (r2 = -0.46) with mean ovum size