This species was formerly known only from the type locality, an unspecified site in the Tana River area in Kenya, which is not possible to map at this time. New individuals were recorded from three nearby sites in the the Ngaya forest in Nyambene Hills (1,232-1,334 m asl), Meru county, Kenya (Measey et al. 2012), with an estimated range of 22 km2 (herein taken as a proxy for extent of occurrence - EOO). However, while no surveys were conducted outside the forest, there are farms with suitable habitat adjacent to the forest; and the species may very well occur in these farmlands and elsewhere in the Nyambene Hills (Measey et al. 2012).
Habitat and Ecology
It is known to occur in dry mid-altitude forest and moist volcanic soil (P.K. Malonza pers. comm. June 2012). It is possible that the species could occur in farmlands adjacent to the Ngaya forest (Measey et al. 2012). On the assumption that its breeding biology is similar to that of other species of Boulengerula, it would be oviparous with direct development.
Originally, the species was known from a single specimen collected prior to 1912. However, between 2007-2010, 12 additional specimens were recorded over the course of three visits; the only dedicated search found it be uncommon (P.K. Malonza pers. comm. June 2012). Its population trend and fragmentation status are currently unknown.
It might be threatened by ongoing forest loss in the Tana River area, but more information is needed before this can be confirmed. Other possible threats, should the species occur in adjacent farmlands, are the intensification of agriculture, including the application of pesticides and herbicides, and the expansion of human settlements.
It is found in Ngaya forest, which is a government-managed community forest (P.K. Malonza pers. comm. June 2012). More research is needed on the species' distribution, population status, natural history and threats. Taxonomic research is needed to clarify the biological identity of some individuals.
Red List Status
Data Deficient (DD)
Listed as Data Deficient in view of continuing uncertainty surrounding its distribution, population status, ecology and threats.
This species was incorrectly synonymized with Schistometopum gregorii, and was resurrected by Wilkinson et al. (2004). Specimens collected from a new locality key-out (as in Wilkinson et al. 2004) as B. denhardti, but there is still uncertainty surrounding the identity of these specimens due to the distance from the type locality (P. Malonza pers comm. June 2012, Measey et al. 2012).
IUCN SSC Amphibian Specialist Group 2013. Boulengerula denhardti. The IUCN Red List of Threatened Species 2013: e.T59496A16943787. http://dx.doi.org/10.2305/IUCN.UK.2013-2.RLTS.T59496A16943787.en .Downloaded on 23 January 2019