In 1998 I identified several small fishes
from Río Potrero Grande, Peninsula Santa Elena,
Área de Conservación Guanacaste (ACG), Costa
Rica (collection information in Janzen 1998),
as Poeciliopsis gracilis, a widespread species
known from southern Mexico to Nicaragua,
although it lacked the typical midlateral spots of
that species, and suggested that a larger series
would be useful to determine whether the lack
of any pigment pattern was truly typical of this
population of Poeciliopsis. These specimens
also were needed to provide additional mature
male specimens for comparisons.