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 km
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.
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. In: IUCN 2014