Complex sentence: The imitator salamander is listed as least concern by the IUCN Red List of Threatened Species, because, although the total size of the population is unknown, the number of salamanders seems to be stable.
Split into simpler sentences: The imitator salamander is listed as being of "Least Concern" by the IUCN Red List of Threatened Species. This is because, although the total size of the population is unknown, the number of salamanders seems to be stable.