A diploid surrounded by polyploids: tadpole description, natural history and cytogenetics of Odontophrynus maisuma Rosset from Uruguay (Anura: Cycloramphidae)

Abstract

Odontophrynus maisuma is a recently described diploid species of the diploid-tetraploid O. americanus complex. It inhabits coastal regions of Uruguay and southern Brazil. Tadpoles of O. maisuma at stages 33–36 are about 47 mm of total length, and similarly to that of other Odontophrynus are typical pond dwelling anuran larvae; the oral disc is small and laterally emarginated, bearing a single row of marginal papillae interrupted by a large dorsal gap. The labial tooth row formula is 2(2)/3(1); sometimes A2 and P1 are not divided. The advertisement call consists of notes that last 570– 785 ms, composed of 43–57 pulses, and with a dominant frequency between 1124–1211 Hz. The chromosome complement is composed by 11 biarmed chromosome pairs (2n = 2x = 22; NF = 44), with evident positive C-bands in the centromeric regions of all chromosome pairs, in the short arms of pairs 2 and 4, and in the long arms of pair 6 and 9. Nucleolar Organizer Regions (Ag-NORs) are located interstitially in the short arms of both chromosomes of pair 4. Preliminary data suggests that erythrocyte morphology could be used to discriminate between diploid and tetraploid tadpoles of Odontophrynus.