Rhoptropus nivimontanus, Parrinha & Marques & Tiutenko & Heinicke & Bauer & Ceríaco, 2025

Parrinha, Diogo, Marques, Mariana P., Tiutenko, Arthur, Heinicke, Matthew P., Bauer, Aaron M. & Ceríaco, Luis M. P., 2025, A new species of Namib Day Gecko (Gekkonidae: Rhoptropus Peters, 1869) from the Serra da Neve inselberg, southwestern Angola, Zootaxa 5569 (3), pp. 439-458 : 448-453

Rhoptropus nivimontanus sp. nov.

urn:lsid:zoobank.org:act:160FC9A9-AA1F-4231-B25A-D7BFAFF998C1

( Figs. 4–8 )

Rhoptropus aff. montanus : Marques et al. (2024a: 189)

Holotype. MUHNAC / MB03-1706 (field number LMPC 3120), an adult male collected by Mariana P. Marques, Luis M.P. Ceríaco, Diogo Parrinha and Arthur Tiutenko near Catchi village, Serra da Neve [-13.7618°, 13.2514°, 1614 m], Namibe Province, Angola, on 27 October 2022.

Paratypes. An adult female ( MUHNAC / MB03-1707 , field number LMPC 3121) and a juvenile ( MUHNAC / MB03-1708 , field number LMPC 3145), with the same collecting data as the holotype .

Diagnosis. A medium sized Rhoptropus with a maximum SVL of 55 mm (MUHNAC/MB03-1707), body stout, partly regenerated tail about the same length as SVL ( Figs. 4 , 5 ). Head wide, with rounded snout. Nasal swellings separated by 2 INS; SL 9–11; IL 8. A well-defined row of enlarged chin shields behind infralabials. Dorsal scales irregularly granular, 62–65 across midbody. Precloacal scales slightly enlarged, bearing 7 pores in males. Digits relatively stout, with 16–18 subdigital scales and lamellae under fourth finger (8–10 SF4 + 8 LF4) and 19 under fourth toe (10–11 ST4 + 8–9 LT4). Tail distinctly segmented, wider at the base and smoothly tapering. Subcaudals transversely enlarged, disposed in a single row with three scales per tail segment. Dorsum greenish blue with a somewhat irregular, yellowish green pattern covering top of head, becoming darker and more reticulated from shoulders to base of tail, interspersed with scattered black speckles; ventral parts light blue.

Rhoptropus nivimontanus sp. nov. differs from all its congeners in its blue and green coloration without any reddish pattern, pale or black spots on dorsum (versus dorsum pale brown to black with reddish or black pattern in other species). It further differs from R. boultoni by having fewer dorsal scales across midbody (62–65 versus 74–87); 2 internasal scales (versus 1), and fewer subdigital scales and lamellae under fourth finger (16–18 versus 18–23) and fourth toe (19–20 versus 20–27); from R. benguellensis by having a blue ventrum (versus creamy white) and 2 internasal scales (versus 1); and from its sister species, R. montanus , by having more dorsal scales across midbody (62–65 versus 54–61). The male also has more precloacal pores than males of R. montanus (7 vs. 5–6).

Description of the holotype. Mensural and meristic characters for the holotype are presented in Table 3 . Adult male with a nearly complete, original tail ( Figs. 4–5 ). Body robust (AGD/SVL 0.41). Head moderately long (HL/ SVL 0.29), wide (HW/HL 0.73), weakly depressed (HH/HL 0.36), distinct from neck. Snout medium (ES/HL 0.43), rounded, with blunt profile. Canthus rostralis not prominent; shallow depression present immediately behind nasal swellings. Eye small (ED/HL 0.17), its diameter shorter than distance from eye to tip of snout (ED/ES 0.39). Supracilliaries small and slightly pointed; no supraciliary dermal fold present. Ear opening vertically ovoid, situated below eye level, smaller than eye diameter (EH/ED 0.56), with small dermal fold extending from superior margin; distance from eye to ear greater than eye diameter (EE/ED 1.71). Rostral wider than deep, with small backwards prolongation between nasal swellings, in contact with first supralabial and two nasals at each side, and two internasal scales. Nostril situated between three weakly swollen circumnasal scales, oriented dorsally; nasal swellings separated by two INS, followed posteriorly by three smaller scales. Scales on snout larger than those on dorsum and occiput; largest located in front of eye, slightly conical and keeled. Mental greatly elongated and tapering to a point posteriorly, in contact with first infralabial on each side and median chin shield posteriorly. A well-defined row of enlarged chin shields is present, bordering mental and first three infralabials on each side, extending obliquely backwards along gular region. Gular scales irregular in size, those immediately posterior to chin shields slightly larger than those on throat. SL 11/10 (R/L); IL 8/8 (R/L), first two greatly elongated; small intrusive scale present between IL III and IV on left side. Dorsal scales small and granular, rounded, with weak tendency to become larger towards flanks, 65 across midbody. Ventral scales larger than dorsals, smooth, rounded to sub-hexagonal, slightly imbricate on chest. Precloacal scales slightly enlarged, rounded to sub-hexagonal, bearing 7 continuous pores disposed in a chevron. Limbs long and stout (FLL/SVL 0.15, CL/SVL 0.18); scales on limbs smooth and juxtaposed; those on anterior and ventral aspect of hindlimbs distinctly larger, as well as those on anterior aspect of forearm; scales on palms and soles small and rounded. Digits relatively stout, wider on distal portion; covered above with somewhat enlarged scales distally; clawless or with small triangular scale in place of claw. Ventral surface of digits covered with enlarged scales along the midline (non-scansorial), followed by undivided (except for distalmost) transverse lamellae under distal expansion. Fourth finger of right manus with 10 enlarged scales along midline and 8 transverse lamellae on distal expansion; fourth toe of right pes with 11 enlarged scales along midline and 9 transverse lamellae on distal expansion. Relative length of digits III>IV>II>I=V (right manus); III=IV>V>II>I (right pes). Tail slightly shorter than SVL (TAL/SVL 0.84), last 2 mm regenerated, weakly depressed, wider at base, tapering to point. Tail segmented, with distinct lateral constrictions between proximal segments, less conspicuous distally; dorsal surface covered with smooth, granular scales disposed in rows, slightly larger than dorsals; subcaudal scales irregularly enlarged in first 3 segments, fourth segment with 3 pairs of enlarged scales on midventral section and following segments with a single row of transversely enlarged scales, disposed in 3 scales per tail segment. Regenerated portion of tail unsegmented, with a single row of enlarged scales along midventral section.

Coloration in life ( Fig. 4 ): Dorsum greenish blue; a light yellowish green hue begins behind the nasal swellings and extends through interorbital region to occiput, where it is more distinct; green pattern becomes progressively darker and more reticulated from shoulders towards base of tail, interspersed with scattered black speckles. Limbs mostly homogeneous, with faint and irregular dark shades on hindlimbs; enlarged scales over distal expansion of digits black centered. Ventral parts light blue, slightly darker on precloacal and subcaudal regions.

Coloration in preservative ( Fig. 5 ): Dorsum dark greyish blue; green pattern on dorsum reduced to dull dark brown; on dorsal aspect of head, light green pattern replaced by a distinct black patch, starting behind internasal granules and between postnasal depressions, extending through forehead and interorbital region above frontal bone and fading at occiput. Ventral parts blue.

Variation. Mensural and meristic variation among the type series is presented in Table 3 . Both paratypes agree entirely with the holotype in terms of coloration. Female paratype MUHNAC / MB03-1707 lacking precloacal pores or pits; mostly clawless, bearing minute claws on digits I and V of left pes. Tail broken in both paratypes prior to collection, after first ( MUHNAC / MB03-1708 ) and third ( MUHNAC / MB03-1707 ) postpygal tail segments.

Distribution. Rhoptropus nivimontanus sp. nov. is only known from the type locality near Catchi village, in the highlands of the Serra da Neve inselberg, Namibe Province, Angola ( Fig. 6 ). Considering the substrate specificity of the genus and the ecological isolation of the inselberg, it is assumed to be endemic to higher elevation areas of Serra da Neve.

Habitat and natural history notes. Very little is known about the ecology and natural history of R. nivimontanus sp. nov.. The type series was collected at roughly 1600 m above sea level in an area dominated by Miombo woodlands on the highlands of the inselberg ( Huntley 2023; Marques et al. 2024a). Specimens were found in a riparian area with denser vegetation and barely any granite outcrops ( Fig. 7 ), in contrast to surrounding woodlands in the inselberg occupied by congener R. aff. barnardi . It was observed together with Lygodactylus nyaneka Marques, Ceríaco, Buehler, Bandeira, Janota & Bauer, 2020 on tree branches, suggesting more arboreal rather than rupicolous habits.

Etymology. The specific epithet “ nivimontanus ” is formed by the combination of the Latin words “ nivis ” (genitive singular of nix, i.e., snow) and “ montanus ” (nominative adjectival of mons, i.e., pertaining to mountains) ( Brown 1956). It is given in reference to the species’ endemic distribution in the Serra da Neve inselberg, whose Portuguese name directly translates to “Mountain of the Snow”. We suggest the English and Portuguese common names “Serra da Neve Day Gecko” and “Osga Diurna da Serra da Neve”, respectively.

Conservation. Rhoptropus nivimontanus sp. nov. is known only from three specimens and is apparently endemic to the Serra da Neve inselberg. Assuming that the species is homogeneously distributed throughout the inselberg, we estimated an extent of occurrence of approximately 630 km 2 using the GeoCAT Geospatial Conservation Assessment Tool ( Bachman et al. 2011). Despite its remoteness, the landscape near human settlements is visibly transformed, with large deforested areas dedicated to agriculture or cattle pastures ( Fig. 8 ; Marques et al. 2024a). Considering the apparent association of R. nivimontanus sp. nov. with arboreal habitats and riparian areas, it might become particularly vulnerable to deforestation, an alarming cause of habitat loss in the highlands of the Angolan Central Plateau ( Mendelsohn 2019). Currently available data does not allow for an unambiguous assessment of the conservation status of R. nivimontanus sp. nov. While we recommend the status of Data Deficient for this species, further surveys targeted at Serra da Neve and other inselbergs in the region, and a formal conservation assessment are warranted, especially considering the susceptibility of montane species to climate change ( Sinervo et al. 2010; Moreira et al. 2023).

Figures

FIGURE 4. Dorsal (A) and ventral (B) views of the holotype of Rhoptropus nivimontanus sp. nov. in life (MUHNAC/MB03- 1706). Photos by AT.

FIGURE 5. Preserved holotype of Rhoptropus nivimontanus sp. nov. (MUHNAC/MB03-1706). Photos by DP.

FIGURE 6. Distribution of Rhoptropus nivimontanus sp. nov. and the boultoni “group” inAngola. Stars represent the respective type localities.

FIGURE 7. Habitat of Rhoptropus nivimontanus sp. nov. at the type locality near Catchi village, on the highlands of Serra da Neve, Namibe Province. Photo by LMPC.

FIGURE 8. General view of Catchi village and plateau, with riparian gallery and type locality of Rhoptropus nivimontanus sp. nov. in foreground (red arrow). Photo by LMPC.