Rhampholeon msitugrabensis, Hughes & Behangana & Lukwago & Menegon & Dehling & Wagner & Tilbury & South & Kusamba & Greenbaum, 2024

Hughes, Daniel F., Behangana, Mathias, Lukwago, Wilber, Menegon, Michele, Dehling, J. Maximilian, Wagner, Philipp, Tilbury, Colin R., South, Trisan, Kusamba, Chifundera & Greenbaum, Eli, 2024, Taxonomy of the Rhampholeon boulengeri Complex (Sauria: Chamaeleonidae): Five New Species from Central Africa’s Albertine Rift, Zootaxa 5458 (4), pp. 451-494 : 480-481

Rhampholeon msitugrabensis sp. nov. Hughes, Kusamba, Menegon, and Greenbaum

Albertine Rift pygmy chameleon

urn:lsid:zoobank.org:act:C55B5EC4-4A4B-4D88-B318-0F122C506F33

Synonymy.

Rhampholeon boulengeri — de Witte 1965 (partim), Tilbury & Tolley 2015 (partim), Spawls et al. 2018 (partim), Tilbury 2018 (partim)

Rhampholeon sp. 4 — Hughes et al. 2018

Etymology. The specific epithet is derived from the Swahili word for forest, msitu, and the German word for rift valley, graben, in reference to the Albertine Rift forests where the species occurs.

Holotype. UTEP 21709 (field no. ELI 1159 ), adult female, BURUNDI, Bubanza Province, Kibira National Park, Mpishi , 03.06177° S, 29.49343° E, 1986 m elevation, 20 December 2011, collected by E. Greenbaum, C. Kusamba, M.M. Aristote, and W.M. Muninga ( Fig. 13A ).

Paratype (topotype). Same collection details as holotype, three adult females, one adult male, and one juvenile male, UTEP 22739–22743 (field nos. ELI 1160–1164 ) .

Referred specimen. MTSN 7213 , RWANDA, Western Province, Nyungwe National Park, Mount Bigugu (02.45565° S, 29.24927° E, 2669 m elevation) (1 specimen) .

Diagnosis. Rhampholeon msitugrabensis sp. nov. is in the subgenus Rhinodigitum because of its distinctly bicuspid claws, prominent rostral process, smooth plantar surfaces, and phylogenetic placement, thus easily distinguishing it from the six species in the other two subgenera (i.e., Rhampholeon and Bicuspis ): R. gorongosae , R. marshalli , R. spectrum , R. spinosus , R. temporalis , and R. viridis . Rhampholeon msitugrabensis sp. nov. can be distinguished from all other Rhampholeon species by the following combination of traits: (1) lack of prominent mite pockets in the inguinal region distinguishes it from R. beraduccii , R. platyceps , R. chapmanorum , R. maspictus , R. tilburyi , R. bruessoworum , and R. nebulauctor ; (2) presence of prominent mite pockets in the axillary region distinguishes it from R. nchisiensis and R. acuminatus ; (3) distinct supra-orbital and canthal crests distinguishes it from R. hattinghi ; (4) geographic restriction to the Albertine Rift distinguishes it from R. uluguruensis , R. moyeri , R. colemani , R. sabini , R. rubeho , R. nicolai , R. waynelotteri , and R. princeeai ; (5) slightly smaller head height in males, genetic divergence, and allopatric distribution distinguishes it from R. boulengeri ; (6) larger inter-limb lengths in both sexes distinguishes it from R. monteslunae sp. nov.; (7) shorter inter-limb length, hind limb length, and head length in females distinguishes it from R. nalubaale sp. nov.; (8) genetic divergence and non-overlapping elevational range at sites of co-occurrence distinguishes it from R. plumptrei sp. nov. and R. bombayi sp. nov.

Genetic differentiation and variation. A summary of pairwise sequence divergence for three DNA markers (16S, ND2, and RAG-1) among individuals of R. msitugrabensis sp. nov. and other Rhampholeon species is presented in Supplementary Material 1.

Description of holotype (UTEP 21709). Adult female, SVL 49.4 mm and TL 11.3 mm. Body shape leaf-like. Casque flattened, with short head. Neck indistinct from head. Supra-orbital crests distinct with cluster of tubercles connected by a ridge with 10 tubercles across casque and 15 tubercles from peak-to-peak of crests. Rostral process 1.3 mm, composed of elongated tubercles. Temporal crest discrete with several enlarged tubercles extending posteriorly from mid-eye. Nares open in a posterior orientation. Canthal ridge consists of raised tubercles, one raised higher than others near snout. Ninety-six upper and 88 lower labial tubercles are present along tip of snout to rictus of mouth. Body covered in nearly homogenous, flattened tubercles. Some larger conical tubercles present on dorsal flanks around midbody. Crenulated dorsal crest, more prominent from midbody to nape. Enlarged conical tubercles present on limbs. Claws markedly bicuspid.

Coloration of holotype (in life). A photograph of the holotype is presented in Figure 13A . Background color mottled light brown to gray with several darker brown patches, especially on limbs, tail, and dorsal crest. Top of head light brown and area near snout darker brown. Head exhibits several darker brown patches on ridges and below eye along mouth. Gular region white, which extends from tip of chin to neck region. Two diagonal dark brown lines extend from near dorsal crest posteriorly to lateral flanks, resembling veins of a leaf. Ventral region a much lighter color than body.

Variation. A summary of descriptive morphometrics for R. msitugrabensis sp. nov. is presented in Table 4 , comparative boxplots in Figure 4 , and measurements of the type specimens in Table 8 . Morphological proportions are generally consistent with those of the holotype. Males have smaller body sizes (M: mean 41.7 mm, range 33.6–46.8 mm, n = 3; F: mean 47.8 mm, range 45.7–49.4 mm, n = 4) and longer tails than females (M: mean 12.4 mm, range 11.5–13.7 mm, n = 3; F: mean 10.9 mm, range 10.5–11.3 mm, n = 4).

Reproduction. Unknown. The smallest specimen examined ( UTEP 22741 ) was collected on 20 December 2011 with SVL 33.6 mm and TL 11.5 mm from Kibira National Park , Burundi.

Distribution, natural history, and conservation. Rhampholeon msitugrabensis sp. nov. is found in montane forests at an elevation range of 1986–2699 m. Most specimens were collected from forest edges at Mpishi near Kibira National Park at 1986 m elevation. A single male specimen (MTSN 7213) was collected from Mt. Bigugu in Nyungwe Forest National Park at an elevation of 2699 m. Rhampholeon bombayi sp. nov. was also found in Nyungwe Forest National Park but allopatrically to R. msitugrabensis sp. nov. at Kamiranzovu Swamp with an elevation range of 2003–2330 m and, also at nearby Cyamudongo Forest with an elevation range of 1857–2033 m. Specimens have been collected from two protected areas in the Rugege Highlands: Nyungwe Forest National Park, Rwanda, and Kibira National Park, Burundi. Nyungwe Forest National Park is the largest protected area in Rwanda, and Kibira National Park is the largest protected area in Burundi. These parks form a continuous forest block, but the nutrient-rich soils of these highlands attract farmers in high densities, which puts pressure on the remaining forest fragments ( Burgess et al. 2007). Other lizard species collected near the type locality were typical Albertine Rift lizard fauna, including Adolfus africanus , Chamaeleo dilepis , Congolacerta vauereselli , Hemidactylus mabouia , Lygodactylus kibera , Kinyongia rugegensis , Trioceros ellioti , T. johnstoni , Trachylepis striata , and T. maculilabris .

Figures

FIGURE 4. Box plots showing variation in external traits of the Rhampholeon boulengeri complex from the Albertine Rift, Central Africa. Sample sizes for each species are denoted in the bottom right quarter. Males and females are separated to show degree of sexual-size dimorphism across members of the complex. All measurements are in mm. Plots show the median, 1st and 3rd quartiles, minimum and maximum inter-quartile ranges, and outliers. Refer to text for description of the linear measurements.

FIGURE 13. Photograph of Rhampholeon msitugrabensis sp. nov. in life. (A)—Adult female holotype (UTEP 21709) from Kibira National Park, Burundi.