Trioceros quadricornis gracilior Böhme and Klaver, 1981

Ineich, Ivan, LeBreton, Matthew, Lhermitte-Vallarino, Nathaly, Abstract. - The, Laurent Chirio, Oku, Mount & Highlands, Bamenda, 2015, The reptiles of the summits of Mont Oku and the Bamenda Highlands, Cameroon *, Amphibian & Reptile Conservation (e 108) 9 (2), pp. 15-38 : 19-20

Trioceros quadricornis gracilior Böhme and Klaver, 1981 (17 specimens)

Material: MNHN-RA 1998.0434-0435 (two specimens, Mt. Oku , above Oku village, elev. 2,200 m, coll. CamHerp L. Chirio, June 25, 1998) – MNHN-RA 2005.2715- 2720 (six specimens, Mt. Oku , Elak Oku village, 6.202°N and 10.505°E, elev. 2,000 m, coll. CamHerp M. LeBreton and L. Chirio, July 8, 2002) – MNHN-RA 2005.2722 ( Oku Manchok , 6.241°N and 10.524°E, elev. 2,130 m, coll. CamHerp M. LeBreton and L. Chirio, December 14, 2002) – MNHN-RA 2005.2723 ( Mt. Oku , Lake Oku, 6.20°N and 10.45°E, elev. 2,250 m, coll. CamHerp M. LeBreton and L. Chirio, April 19, 2000) – MNHN-RA 2005.2724, 2005.2726-2727 (three specimens, Mt. Oku , Oku village, 6.202°N and 10.505°E, elev. 2,000 m, coll. CamHerp M. LeBreton and L. Chirio, April 19, 2000) – MNHN-RA 2005.2725 ( Mt. Oku , Simonkuh village, 6.234°N and 10.572°E, elev. 2,109 m, coll. CamHerp M. LeBreton, July 8, 2002) – MNHN-RA 2007.1423 (male; Mt. Oku , Oku village, 6.202°N and 10.505°E, elev. 2,000 m, coll. I. Ineich and N. Lhermitte-Vallarino, May 8, 2007) - MNHN-RA 2007.1424 (male; Mt. Oku , Oku village, 6.202°N and 10.505°E, elev. 2,000 m, coll. I. Ineich and N. Lhermitte-Vallarino, May 8, 2007) - MNHN-RA 2007.1426 (male; Mt. Oku , Oku village, 6.202°N and 10.505°E, elev. 2,000 m, coll. I. Ineich and N. Lhermitte-Vallarino, May 7, 2007) .

Barej et al. (2010) revised the T. quadricornis complex with additional materials and molecular data. The morphological differences between the populations of the south (Mt. Kupe and Mt. Manengouba) and north (BH to Obudu Plateau in Nigeria) were supported by genetics, thus confirming the subspecific status of T. q. quadricornis (Tornier, 1899) and T. q. gracilior Böhme and Klaver, 1981. T. q. gracilior is present at Mts. Bamboutos, Mbulu Hills ( Gonwouo et al. 2006), Mt. Lefo, Mt. Oku and onto the Obudu Plateau in Nigeria, while T. q. quadricornis occupies the forests of Mt. Manengouba and Mt. Kupe. This study also relegated Chamaeleo eisentrauti , once considered a valid species, to subspecific status as T. q. eisentrauti (Mertens, 1968) . This form is endemic to Rumpi Hills in western Cameroon. All these taxa occupy primary mountain forests, and T. q. gracilior occurs up to 2,700 m in altitude. Tilbury (2010) reported the taxon between 1,600 –2,500 m. The separation between these three subspecific taxa, attested by their low genetic divergence, is thus probably recent and associated with the altitudinal shifting of cool forests to the mountain peaks after the end of Pleistocene glacial periods.

Trioceros q. gracilior ( Fig. 7) is an endemic subspecies of Cameroon and neighboring Nigeria (Plateau Obudu). This is an arboreal montane forest lizard (mostly met at the interface forest/grassland) that is still relatively abundant locally, such as around the village of Elak Oku (6.244°N, 10.508°E, elev. 1,970 m). Its altitudinal distribution reaches 2,400 m above sea level at Mt. Oku (Ijim Ridge; Wild 1994) and 2,700 m at Mt. Mekua in the Bamboutos ( Gonwouo et al. 2006; Barej et al. 2010). Its perch height is much greater than that of T. serratus (see below) and averages around 1.9 m at Mt. Oku ( Gonwouo et al. 2006). Wild (1994) found the chameleon from one m above the ground to the top of the canopy at Mt. Oku, with a preference for branches near streams. The minimum night temperature recorded in its habitat at 2,400 m is 4.7 °C in December 1993 ( Wild 1994). The female lays from 6 to 24 eggs that are partially incubated before being laid ( Abate 1994).

This species is particularly threatened by trade in exotic pets, and especially by rampant habitat destruction (deforestation, cultures, bush fires, grazing). Eucalyptus, an alien tree widely introduced in the region creates unfavorable habitat. However, the species seems able to persist in fragmented forest remnants and transitional habitats ( Fig. 8). Its densities are estimated at four times higher at Mt. Oku compared to populations in Mbulu Hills ( Gonwouo et al. 2006), and almost twice as high as at Mt. Manengouba (T. q. quadricornis ). The conservation status of the species remains nevertheless very fragile and sensitive to environmental degradation. The threat of commercial harvesting is now better regulated by effective measures implemented mostly via European Union CITES regulation.