Bioacoustics of Pleurodema kriegi

Distribution. The species is currently known from Pampa de Achala, Córdoba province ( Fig. 1 ) (see Barrio 1977 , Kolenc et al. 2009 ) and cited to near Alpa Corral, Córdoba province by Ávila and Priotto (1995) . However, the last record should be corroborated because the locality is to the south of the new species with octoploid chromosomic complement and the specimens could be octoploid, too. Ecology. Pleurodema kriegi males were acoustically active from the first rains of austral spring (November) to March from 21.00 hs. to 3.00 hr. (sunset time: 21.00 – 21.30 hr) Pleurodema kriegi breeds in temporary and semipermanent ponds with vegetation at the edges, or aquatic vegetation, and 10 to 40 cm deep ( Fig. 9 ). The males emit their calls floating in the surface of the water or underground near the edge of ponds. The eggs are deposited in semisubmerged eggs-masses and adhered to the aquatic vegetation. The amplexus is axillary. This species was observed in sympatry with Rhinella achalensis , and in syntopy with R. arenarum , Odontophrynus achalensis and Hypsiboas cordobae . The tadpole of Pleurodema kriegi was recently redescripted by Kolenc et al. (2009) and a comparison with Pleurodema bibroni was performed.

Diagnosis. A small species of Pleurodema ( 33.24 mm SVL), characterized by: (1) relatively small size; (2) snout short, canthus rostralis rounded in dorsal view and truncate in profile; (3) lumbar glands present, 1 ½ eye diameter; (4) round tympanic annulus, almost concealed; (5) tympanum length half of the eye diameter; (6) vomerine teeth absent, (7) comissural gland prominent; (8) brilliant red-orange spots on the groin and around lumbar glands; (9) ploidy level 2n= 4x =44; (10) axillary amplexus; (11) egg deposition in gelatinous nest attached to vegetation; (12) compound advertisement call with tri-pulsed pulse groups, average dominant frequency 1823 Hz. According to external morphology, Pleurodema kriegi , Pleurodema bibroni and the new species described below are cryptic and the properties of their advertisement calls are similar (see above). Pleurodema kriegi differs from the new allopatric species from Sierra de Comechingones by having tetraploid chromosomic complement (octoploid in the new species) and by having a lower pulse rate (55.9 pulses/sec in Pleurodema kriegi and 65.7 pulses/sec in the new species). Pleurodema kriegi and Pleurodema bibroni are the only tetraploid species of the genus. They are morphologically very similar and although Laurent (1975) found some morphological differences between these entities, an unequivocal distinction between these taxa is not possible. The advertisement call of Pleurodema kriegi is similar to Pleurodema bibroni , too. Barrio (1977) detected difference in the pulse rate between these taxa, although the temperatures of recording are different and this environmental variable can affect this temporal variable of the call; Kolenc et al. (2009) found no acoustic differences between these two species. Barrio and Rinaldi de Chieri (1970) found secondary constriction chromosomes 12 only in Pleurodema kriegi . Ultimately, Pleurodema kriegi and P. bibroni were considered as distinct species by Barrio (1977) based mostly on biogeographic and ecologic differences.