Despite directed surveys for this species in areas of suitable habitat by Dussart (1982), no evidence of remaining populations of this large calanoid has been uncovered. Since the early 1980's, the region of collection has undergone extensive urbanization and agricultural expansion with ongoing conversion of wetland habitats. It seems highly improbable that the presumed limited freshwater habitat of this species escaped these threats, and as such this species is listed as Extinct.

This calanoid was described by Kiefer (1930) from "Tananarive" (presumably Antananarivo), Madagascar (Kiefer 1930, Lindberg 1951, Dussart 1982). It is known only from the type collection (not collected by Kiefer); no other populations have been found despite directed surveys by Dussart (1982). There does not appear to be any elevation data associated with the record.

Dussart and Defaye (1983: p. 110-111) listed Tropodiaptomus ctenopus as recorded from Madagascar, Asia, and Sri Lanka, and cited Fernando (1974) as the authority for the Sri Lanka record. However, of the three species of Tropodiaptomus recorded by Fernando (1974) in his summary of Sri Lankan freshwater invertebrates, and in his 1979 paper integrating additional collections from a range of habitats, none is referable to T. ctenopus (J. Reid pers. comm. 2024). Therefore, without clear evidence that it occurred anywhere away from the type locality, it is here considered endemic to Madagascar.

It appears to be known only from the type series described by Kiefer (1930) (Dussart 1982). Extensive surveys by Dussart (1982) in appropriate areas and habitats failed to relocate this species. The region has been highly modified by urbanization and agricultural conversion since the type series was collected, and it seems highly probable that this copepod is now extinct.

It was almost certainly collected from a freshwater pool. While little else is known about the habitats of this species, it seems likely that it lived in small perennial or ephemeral ponds, pools, marshes, ditches and such, and may have been seasonal (Janet Reid pers. comm. 2024).

The area in which this species was historically collected has since undergone extensive urbanization and conversion of land to agricultural use. It seems very probable that any small freshwater pool or wetland will have been severely impacted by these changes, and it is unlikely that suitable habitat remains for this species to persist.

There is no use or trade in this species.

Although new surveys of freshwater pools and habitats, both within and around the Antananarivo area could try to locate existing populations of the copepod it seems increasingly unlikely that these will be successful.