P. spinifer POCOCK, 1898 = Eucratoscelus constrictus (GERSTÄCKER, 1873)
Eucratoscelus constrictus are'nt availaible in the hobby, we really dont know much about their behavior. They dont share the large and hairy leg IV so you could have confused it with a Pterinochilus sp. This species is recored from Taveta, Voi and Mbuyuni, in south of Kenya, while the Eucratoscelus pachypus is recorded mostly from Kenya, and probably in the north part of Kenya
Saying how a species will react and behave in its environement is just impossible, each individu are different.
The first imports of Pterniochilus murinus UCF were sold as P. spinifer, then as P. sp. "Usumbara" and then P. mammilatus, but were cleared out by Gallon who placed this colour form with the species P. murinus (but as regional colur form from the Usumbara mts. thus the UCF = Usumbara Color Form). Basically in hobby regards they are one and the same species, though in nomenclatural regards the situation is as Cedrik states.