The status of this species has been disputed and Johnson, Murray and Clarke (1992) believed that it may have been a sinistral variety of P. affinis, however this similarity is only superficial.

Partula cytherea is a tree snail species endemic to Tahiti, French Polynesia. After the introduction of the carnivorous Rosy Wolfsnail (Euglandina rosea) to Tahiti in 1977, populations and species of native partulid snails began to disappear rapidly as a result of predation. No live individuals were found in this species' main range (Papenoo Valley) during searches in the 1980s and 1990s, and during the intensive surveys on the main island of Tahiti Nui in the early 2000s, leading to its previous assessment of Extinct. However, more recent information confirmed that a relict population survived on Mt. Marau in 2005, and this may continue to persist in very low abundances. Therefore, this species is reassessed as Critically Endangered (Possibly Extinct), until further surveys confirm whether this species is still extant.

This species is endemic to Tahiti, where its distribution was limited to the Papenoo Valley and nearby mountain ridges and it was considered a rare species. It was considered to be Extinct after no live individuals were found in this species' main range (Papenoo Valley) during searches in the 1980s and 1990s and during the intensive surveys on the main island of Tahiti Nui in the early 2000s (Coote 2005). However at least one live individual was found on Mt. Marau in 2005 (T. Coote in Gerlach 2016) and it is now thought that this species may continue to persist at higher altitudes.

No data are currently available on population size or trends for this species. It may be undergoing extreme fluctuations in population size caused by fluctuation in invasive predator populations. Further research is needed to confirm whether this species is extant or not.

This snail is an arboreal species found in high forest areas.

This species always had a limited range and disappeared rapidly following the introduction of the carnivorous Rosy Wolfsnail (Euglandina rosea), as shown by the discovery of abundant fresh shells in areas occupied by this predator in 2003–2005 (Coote 2005). A population survived above 1,400 m asl on Mt. Marau in 2005, where fresh shells have been collected and at least one live individual was seen. When found, the abundant fresh shells indicated that this population appeared to have just suffered a collapse. However, the predator does not establish permanent populations at this altitude, enabling relict populations of partulids to survive. The predatory New Guinea Flatworm (Platydemus manokwari) is also present, but this species also does not seem to be a permanent occupant of the high altitude forests.

Many partulids were used in necklace making but no trade was recorded in this species.

No conservation action has yet been taken. for this species. Further surveys are required to establish if the species persists, and to determine what conservation actions would benefit this species which was present in 2005, albeit in low numbers.