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Plagiometriona centromaculata sp. nov. from Bolivia: Santa Cruz department and P. hyalina sp. nov. from Ecuador: Morona-Santiago and Sucumbíos provinces are described and figured. Both species are associated with Solanum species (Solanaceae).
Diel Vertical Migration (DVM) is a widespread behavior in zooplankton. Although considered to be a predator avoidance behavior in most cases, DVM is also influenced by the distribution of food, competitive interactions and UV (Ultraviolet) radiation. In this paper we report the day and nighttime vertical distribution of the common zooplankton species in nine high altitude tropical Andean lakes to obtain an idea of the range in vertical distribution patterns in Andean lakes. The lakes are situated between 4000 and 4545 m a.s.l. The maximum depth of the lakes varied from 5 to 24 m, and the area varied between 0.6 and 20.75 ha. Daphnia pulex (Leydig 1860) showed tendencies for a normal vertical migration behavior in all lakes sampled irrespective of whether the lakes contained fish. The population resided deeper in the water column during the daytime than during the night, although migration amplitude differed strongly among lakes. In many lakes, there was an important daytime “deficit” in the number of individuals caught, suggesting that the animals stay close to the bottom of the lake during the day. It suggests that UV radiation is the more likely factor influencing the DVM of Daphnia. Copepods and rotifers showed reverse DVM in some lakes. Our data suggest that the DVM behavior of copepods and rotifers in the studied lakes may in part be determined by the avoidance of competition from Daphnia pulex.
Fossil remains of South American tapirs are often fragmentary and scarce compared with those of other mammals that entered South America during the “Great American Biotic Interchange”. Here, we review and add to the Pleistocene tapir remains from the Tarija Valley (Bolivia), and provide a taxonomic re-evaluation of Tapirus tarijensis. T. tarijensis was a large-sized animal, approximating the size of the living Malaysian T. indicus and the extinct North American T. haysii. The geographical distribution of Pleistocene records of Tapirus in South America indicates that T. tarijensis was the only known species inhabiting the Tarija Valley during this time.
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