Subgenus Carabomorphus Kolbe, 1895
Carabomorphus Kolbe, 1895: 57 (type: brachycerum Gerstaeker, 1884)
According to Jeannel (1940: 64), the African wingless Calosoma, more linked to the mountain habitat of ground and grassland, belong to genera: Carabops, Orinodromus and Carabomorphus, and their origin can be traced back to the Castrida - Caminara phyletic line. They differ from the other Calosoma belonging to this line because the lack of serration on the margin of the elytra.
We think that the genera of Jeannel should be mantained as subgenera and therefore we consider Carabomorphus and the others as subgenera.
The species of Carabomorphus, as those belonging to Orinodromus and Carabophanus, have smooth mandibles and reduced metaepisterna without punctuation, but they are easily distinguished because the inner armature of their penis has an overdeveloped ligule.
The body shape is roughly similar in all three species of Carabomorphus. The sculpture of the elytra has 16 intervals, all of them of the same width and height. It is so in brachycerum, and it is so in populations of catenatum and masaicum, living at medium altitudes. On the contrary, in the populations of the last two species mentioned, living at higher altitudes, the sculpture of the elytra is characterized by diversely developed intervals and it can be very variable, even within the same population.
In the case of brachycerum, the presence into two mountains separated by dry savanna, of two populations that are not differentiated morphologically, is difficult to explain in biogeographical terms, and led to suggest the existence of some sort of bridge in recent colder times (Brühl 1977: 238).
catenatum and masaicum, on the contrary, give rise to a series of strikingly different populations that occupy ecological niches at different altitudes of the same mountain. In these cases it is more difficult to decide on the actual isolation of the populations and on their systematic position. So, also taking into account the existence of numerous transitional forms, rather than interpreting any population morphologically differentiated as a distinct subspecies, it would be preferable to collect, at least temporarily, these populations in a few large clusters that can be considered as distinct subspecies
The three species of Carabomorphus are found in Kenya: on the Mount Kenya, and on the bottom and on both sides of the terminal part of the Rift Valley (Mau escarpment and Monts Aberdare); and in Tanzania, on the slopes of Mount Kilimanjaro and Mount Meru.