Rhampholeon boulengeri Steindachner, 1911

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 : 462-465

Rhampholeon boulengeri Steindachner, 1911

Boulenger’s pygmy chameleon

Chresonymy.

Rhampholeon spectrum boulengeri —Loveridge 1951 (fide Wild 1994)

Rhampholeon boulengeri — Fischer 1996, Nečas 2004 (partim), Matthee et al. 2004 (partim), Tilbury 2010 (partim), Glaw 2015 (partim), Tilbury 2018 (partim), Menegon et al. 2022 (partim)

Rhampholeon sp. Itombwe— Hughes et al. 2018

Original diagnosis (verbatim, translated from German by JMD). In body shape matching Rh. brevicaudatus (Matschie) [now Rieppeleon brevicaudatus ( Matschie, 1892) ], but with a short, small, conic rostral process, an anteriorly concave interorbital ridge and without skin fold from the eye to the tail tip. Tail length about one-fifth of the total length. Apart from the two-pointed claw no spine on fingers and toes. Eyelid edge more or less distinctly triangularly acuminate. Temporal ridge and parietal crest well developed. Interorbital edge moderately concave, the two low eyelid processes connected through a transversal ridge. Helmet low, the rear end merging without disruption into the back. Rump high like in Rh. brevicaudatus . Dorsal crest weakly toothed. Scalation non-uniform, the slightly larger tubercles, in particular on the extremities, spine-like pointed.

Head, chest and outer face of extremities, occasionally also the larger or smaller front half of the rump deep black-brown, the remaining part of the rump brownish white. The underside of the tail, which is thickened in its basal part, especially in males, is in cross-section flat in males. Three specimens, among them two males, from the natural forest beyond the sand mountains of the northwestern shore of Lake Tanganyika.

Total length of the largest male 65 mm, tail length somewhat more than 12 mm, greatest rump height 23 mm, head length 13 mm, greatest head width in the eye region 7.5 mm. Only the outermost tail tip is prehensile.

Original syntypes. Two adult males (NMW 16000-1, NMW 16000-2) and one adult female (NMW 16000-3), collected by Rudolph Grauer in 1908. Type locality: “aus dem Urwald hinter den Sandbergen des nordwestlichen Ufers des Tanganyikasees” (i.e., from the dense wooded areas [jungle] beyond the sand mountains of the northwest shore of Lake Tanganyika), further defined as “forest on the Itombwe Plateau” in eastern DRC by Tilbury & Tolley (2015), and subsequently upheld by others (e.g., Hughes et al. 2018; Tilbury 2018). According to JMD, the term “Sandberge” is a misreading of [Graben-] “Randberge” (“rift-flank mountains”), a term used to describe where many other specimens were collected by Rudolf Grauer in the same area around the same time. The capital letters “S” and “R” are similar to each other in the style of German handwriting used at that time known as Kurrentschrift. All other specimens collected by Grauer have the locality as “Randberge.” One of the few localities in that area specified by Grauer is “Ugoma,” which is where he collected one of the syntypes (NMW 8020) of Chamaeleon graueri (= Trioceros johnstoni ), described by Steindachner (1911) in the same work and apparently from the same type locality as R. boulengeri . Consequently, the type locality may refer to Mount Ugoma (04.00000° S, 28.75000° E, 2012 m elevation) in the southernmost part of the Itombwe Plateau, which is in the vicinity of Baraka (ca. 40 km) and Kabambare in modern-day South Kivu and Maniema Provinces, eastern DRC.

Lectotype. Given the absence of a holotype, we designate the male specimen ( NMW 16000-2 ) as the lectotype for the species. This designation formally restricts the type locality to the Itombwe Plateau, DRC, as described above. The specimens NMW 16000-1 and NMW 16000-3 thus become paralectotypes and no longer have any name-bearing function.

Referred specimens. UTEP 21715 (field no. EBG 1613 ) (Bichaka, 03.33872° S, 28.75595° E, 2100 m elevation) , UTEP 21716 (field no. EBG 1700 ) (Bichaka, 03.3374° S, 28.78804° E, 2311 m elevation) , UTEP 21717–21718 (field nos. EBG 1701–1702 ) (Kisakala, 03.3373° S, 28.78791° E, 2264 m elevation) , UTEP 22684–22686 (field nos. DFH 4756–4758 ) (Mibengya, 03.46269° S, 28.58406° E, 2320 m elevation) , UTEP 22687 (field no. DFH 4771 ) (Elumbulumbu, 03.44536° S, 28.56246° E, 2470 m elevation) , UTEP 22688 (field no. DFH 4779 ) (Elumbulumbu, 03.44501° S, 28.56195° E, 2464 m elevation), DRC, South Kivu Province, Itombwe Plateau (9 specimens) .

Description of lectotype (NMW 16000-2). Adult male, SVL 51.3 mm and TL 16.4 mm. Body shape leaf-like. Casque flattened, slightly elevated toward nape, with short head. Four elevated tubercles in center of casque. Neck indistinct from head. Supra-orbital crests distinct with cluster of tubercles connected by ridge of tubercles between crests. Rostral process 2.10 mm, composed of several elongated tubercles. Temporal crest discrete with five enlarged tubercles extending posteriorly from mid-eye. Nares open in a posterior orientation. Canthal ridge consists of raised tubercles, several raised higher above nares. Two raised tubercles below eye posteriorly and a third above rictus of mouth. Body covered in nearly homogenous, flattened tubercles. Several larger conical tubercles present on dorsal flanks around midbody. Largest body tubercle dorsal to forelimbs. Enlarged conical tubercles present on fore- and hind limbs. Crenulated dorsal crest. Claws bicuspid.

Coloration of lectotype (in preservative). Photographs of the lectotype (NMW 16000-2) in preservative are presented in Figure 7D–F . Head color is dark brown with lighter brown to pale orange coloration around mouth, especially on lower jaw. Lighter brown hues begin behind the head and extend posteriorly and ventrally to just beyond forelimbs, and dorsally along crest to about midbody. Forelimbs are darker brown with lighter color on palms. Pale brown to white coloration is present on posterior third of body, extending from just beyond midbody to cover hind limbs, rump, and tail. Larger tubercles on body and limbs dark brown to black, especially largest body tubercle located dorsal to forelimbs.

Variation. A summary of pairwise sequence divergence for three DNA markers (16S, ND2, and RAG-1) is presented in Supplementary Material 1. A summary of morphometrics and measurements of the type specimens are presented in Table 2 and comparative boxplots for the species in Figure 4 . Photographs of the type specimens are presented in Figure 7 and images displaying variation in life for the species are presented in Figure 8 . Males and females are similar in body size, but males have longer tails.

Distribution, natural history, and conservation. The species is distributed in montane forest in eastern DRC at elevations between 2100 and 2470 m. One female specimen (UTEP 22684) collected on 9 June 2015 with an SVL of 50.9 mm and TL of 12.3 mm was gravid. Most data on natural history previously assigned to the nominal taxon (for a summary see Tilbury 2018) actually refers to other, cryptic species (see below).

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 7. Photographs of the lectotype and paralectotypes of Rhampholeon boulengeri. Adult male paralectotype (NMW 16000-1): (A)—lateral view; (B)—dorsal head view; (C)—lateral head view. Adult male lectotype (NMW 16000-2): (D)— lateral view; (E)—dorsal head view; (F)—lateral head view. Adult female paralectotype (NMW 16000-3): (G)—lateral view; (H)—dorsal head view; (I)—lateral head view. Photos by PW, Alice Schumacher, and Georg Gassner.

FIGURE 8. Photographs of various individuals of Rhampholeon boulengeri in life. (A)—Adult male (UTEP 21715) from the vicinity of Bichaka, DRC; (B)—Uncollected adult male from the Itombwe Plateau, DRC; (C, D)—Adult male (UTEP 21716) from the vicinity of Bichaka, DRC; (E)—Habitat view of the forest at Bichaka, DRC; (F)—Another habitat view of the forest at Bichaka, DRC.