Trioceros nyirit, Stipala, Jan, Lutzmánn, Nicola, Malonza, Patrick K., Borghesio, Luca, Wilkinson, Paul, Godley, Brendan & Evans, Matthew R., 2011

Stipala, Jan, Lutzmánn, Nicola, Malonza, Patrick K., Borghesio, Luca, Wilkinson, Paul, Godley, Brendan & Evans, Matthew R., 2011, A new species of chameleon (Sauria: Chamaeleonidae) from the highlands of northwest Kenya, Zootaxa 3002, pp. 1-16 : 7-11

Trioceros nyirit sp. nov.

( Figures 2 B and 5A & B)

Holotype. NMK-L3166/1, adult male, Gatau Pass (2500m), Mtelo massif, northwest Kenya, collected by Jan Stipala and Joash Nyamache on 21st July 2006.

Paratypes. 4 males and 4 females. NMK-L3166/2, male, NMK-L3166/ 3-4, females, southern slopes of Mtelo massif (2200-3100m); NMK-L2990/1 & 5, males, NMK-L2990/ 2-3, females, Gatau Pass, Mtelo massif (2200- 2500m).

Non-type material. NMK-L2998/1-5, males, NMK-L2998/6-11, females, Kaptalamwa and Kapiego (2900- 3000m), Cherangani Hills; BMNH 1969.2588-9, BMNH 1969.2591, BMNH 1969.2595-6, Sondang (3050m), Cherangani Hills.

Diagnosis. A medium sized chameleon (largest male 191mm TL, largest female 180.5mm TL) with heterogeneous body scalation; short, forward-pointing rostral process covered in enlarged scales; straight to weakly curved parietal crest, rising gradually posteriorly to meet the lateral crests to form a prominent, moderately steep triangular casque; This combination of characters differentiates T. nyirit sp. nov. from other species in the bitaeniatus -group.

Description of holotype. Total length 165mm (SVL 80mm, tail 85mm). The scalation is heterogenous with rounded or oval convex tubercles of different sizes scattered on the body and legs and tail. There are two clearly defined horizontal rows of enlarged tubercles on each flank, larger than those elsewhere on the body, the lower row extending between the front and hind legs, the second row higher on the flank. The scales on the belly are fine and relatively homogenous. The dorsal crest is well-developed along the entire length of the dorsal keel and extends onto the proximal two thirds of the tail, decreasing in size posteriorly. It is composed of enlarged conical tubercles, formed into sequential groups of three or four scales, the scales within each group increasing in size posteriorly, the most posterior scale much larger than the one before it. The ventral crest consists of short conical tubercles and is contiguous with the gular crest.

The head has prominent tubercular crests. The supra-orbital crests are continuous with the lateral crests, which rise posteriorly to meet the parietal crest forming a distinct, raised triangular casque. The parietal crest is straight and rises gradually posteriorly. It is forked anteriorly, the branches extending anterio-laterally to contact the supra-orbital crests. The scales on the casque are large, flat and polygonal. The scales between the supra-orbital crests are smaller than on top of the casque and moderately convex. A row of five strongly convex scales form a median ridge between the orbits and is distinct from the flat scales around it. The supra-orbital crests are contiguous with the canthi rostrales and merge anteriorly to form a short, forward-pointing rostral projection, which is covered in enlarged scales and extends beyond the the edge of the snout by 1mm. The sides of the head are covered in moderately enlarged convex tubercles. The scales on the eyelids are fine and weakly heterogenous. The gular region has several longitudinal rows of strongly convex tubercles that border a distinct gular crest. The gular crest is composed of conical scales, short anteriorly, becoming longer under the posterior half of the head, the longest scales about equal in length to the diameter of the eye opening.

The hemipenis is structurally similar to that of T. hoehnelii (Böhme & Klaver 1986) but differs, the two pairs of cogwheels being more strongy serrated. The parietal peritoneum shows only light pigmentation and is not extensive as seen in other members of the bitaeniatus group ( Bauer 1997).

Colour in preservation. The holotype is uniform black.

Variation in paratypes and non-type material. The following snout-vent length (SVL) and tail length measurements were taken from living specimens, some of which were preserved and deposited in the NMK. Mean SVL: males = 76.4mm ± 8.5 (n = 27). Females = 72.9mm ±7.1 (n = 35). Largest male: 191mm total length (SVL = 91mm, tail = 100mm. Largest female: 160mm total length (SVL = 85mm, tail 75mm). Morphometric measurements and inter-orbital scale count of type and non-type specimens are given in Table 3.

Several morphological characters were quite variable. Body scales in some individuals are fine, granular and almost homogenous except for the two rows of tubercles, which in some individuals can be indistinct, especially the lower row. Gular crest development is variable in both Mtelo and Cherangani populations, being very short in some individuals (see Figure 4 B) and long in others, equivalent in length to some specimens of T. hoehnelii . The parietal crest is straight or weakly curved, however it never reaches the extent of strong curvature nor rises steeply anteriorly as seen in T. hoehnelii and T. narraioca .

Colour in life. Holotype was uniform bright green with an indistinct wash of turquoise bands on the body, legs and tail. The eye is bright green with a dark horizontal line passing through it. The dorsal crest and adjacent scales on the dorsal keel, the head crests and rostral projection are dark red. The toes and soles of the feet are bright yellow.

Other males were also typically uniform bright green, the lower flanks, gular region, legs and tail a lighter turquoise-green. The head crests, rostral projection, dorsal crest and adjacent scales on the dorsal keel vary from red to black. When stressed, excited or basking, in males a darker pattern of broad vertical bars appears on the flanks, the rows of flank tubercles remaining light green. Bright yellow toes and soles of the feet were only seen in Mtelo males.

Females were more variable in colour than males. Some females were uniform green, while others were shades of light and dark brown, the body with several broad bands, the flank tubercles and throat cream-white or yellow. The head and dorsal crests and rostral projection were red in most individuals.

Etymology. Named after the Pokot word for chameleon, nyirit . The distribution of T. nyirit sp. nov. occurs mainly within the Pokot tribal area.

Distribution. Trioceros nyirit sp. nov. was recorded between 2900-3150m on the Cherangani Hills and between 2276-3121m on the Mtelo massif. At lower elevations other chameleon species ( T. ellioti and T. conirostratus ) were abundant, suggesting that T. nyirit sp. nov. is restricted to higher elevations. In the Cherangani Hills T. nyirit sp. nov. appears to be widespread as specimens were collected from Sondang (3000m) in the north and Cheptongoi Hills (3000m) to the south of the range. We did not sample between 2300m and 2900m in the Cherangani Hills but T. nyirit sp. nov. is likely to occur below 2900m given its elevation range on Mtelo. We estimated the distribution of T. nyirit sp. nov. using maximum and minimum elevation values from a GPS recorded at collecting localities and using Google Earth. The predicted range size of T. nyirit sp. nov. in the Cherangani Hills (assuming that all sites> 2900m are potential habitat) is 754km 2 and on the Mtelo massif is 93km 2 (> 2276m).

Ecology. On the Mtelo massif, T. nyirit sp. nov. was found on shrubs at the edges of cleared afromontane forest and also in the ericaceous zone above the forest. In the Cherangani Hills, specimens were found on shrubs and small trees at the edge of fields, on hedges and roadside vegetation.

Conservation status. As well as occurring in ericaceous afroalpine vegetation and shrubs at the forest edge, T. nyirit sp. nov. were also collected in disturbed habitats in agricultural landscapes and appears to be relatively abundant in these areas. This suggests that despite its limited distribution it does not seem to be threatened by anthropogenic activities. However, deforestation and conversion of natural habitats to agriculture on the Mtelo massif continues to reduce forest cover (John Yoposiwa, pers. comm.) and rates of habitat change are believed to be high also in the Cherangani ( Wass 1995; Akotsi & Gachanja 2004).

Figures

FIGURE 2. Typical head shape of male T. nyirit sp. nov. and comparison with other morphologically similar or genetically closely related species from the bitaeniatus group. Two specimens of T. hoehnelii are included to show intra-specific variation. A— T. nyirit sp. nov., holotype, Mtelo massif, B— T. hoehnelii, Elgeyo Escarpment; C— T. sternfeldi, Mt. Meru; D— T. schubotzi, Mt. Kenya; E— T. hoehnelii, Mt. Elgon; F— T. narraioca, Mt. Kulal.

FIGURE 4. Phylogeny generated from Maximum Parsimony analysis, based on partial 16 S and ND 4 mtDNA markers. Above branches = MP bootstrap support values. Below branches = Bayesian posterior probabilities. Scale bar indicates the number of nucleotide substitutions.