Scutiger khumbu, Hofmann & Ohler & Baniya & Dubois & Flecks & Jablonski & Schmidt & Dufresnes, 2025

Scutiger khumbu sp. nov.

urn:lsid:zoobank.org:act:3F5B9602-4B6E-467E-9AF3-77D66724ACB7

Figs 6–10; Table 3; Supp. file 1J, L–O

Diagnosis

Scutiger khumbu sp. nov. is assigned to the genus Scutiger based on morphological characteristics and its phylogenetic position ( Fig. 2). It can be distinguished based on multiple nucleotide substitutions in mitochondrial COI, cytb, and 16S sequences, as well as private alleles at the nuclear genes bfib7, ccnb2 and rag1. It can be distinguished from all other congeners by the following combination of morphological features: medium body size (male 41.6–51.1 mm SVL, female 49.4–55.6 mm; Table 3, Supp. file 1J); head wider than long; vomerine and maxillary teeth absent; vocal sac absent; relative length of fingers 3> 4> 2> 1; small black nuptial spines on dorsal surface of first and second fingers, and inner side of third finger in males in breeding condition; inner forearm without spines; relative length of toes 4> 3> 5 ≥ 2 ≥ 1; subarticular tubercles absent; toes unwebbed or rudimentary webbed; a pair of pectoral glands and a pair of axillary glands with small black spines on both glands; abdomen/belly without spines; tubercles on dorsal and lateral surfaces of body (often arranged in lines) and upper limbs; tubercles conical, each tubercle with keratinized tips or 1–2 black spines in breeding condition, entire cone with horned, black coating, studded with small black tips, shimmering like black mica schist when moistened in the preserved state, in particular in specimens from the Khumbu region ( Fig. 6). A triangular or Y-shaped dark brownish pattern can be present on dorsal side of the head (Supp. file 1L–M).

Etymology

The specific epithet ʻ khumbu ʼ is a noun in apposition referring to the Khumbu Himal (also called the Everest region) in Nepal and thus remains unchanged regardless of the gender of the genus.

Type material

Holotype

NEPAL • ♂; Bagmati Province, Dolakha District, Jiri ; 27°41′48″ N, 86°16′30″ E (WGS 84); 3396 m a.s.l.; Jun. 1997; local resident leg.; ZFMK 104174. GoogleMaps

Paratypes

NEPAL • 1 subadult; Bagmati Province, Ramechhap District, Gokulganga ; 27°35′43″ N, 86°20′24″ E (WGS 84); Jun. 1997; local resident leg.; ZFMK 104175 GoogleMaps • 13 ♂♂; Solu Khumbu District, Najing Dingma ; 27°34′33″ N, 86°48′08″ E (WGS 84); 1 Jul. 1973; Alain Dubois and Dominique Payen leg.; MNHN 1977.1246 to MNHN 1977.1250, MNHN 1977.1252, MNHN 1977.1254, MNHN 1977.1256 to MNHN 1977.1261 GoogleMaps • 4 ♀♀; same data as for preceding; MNHN 1977.1251, MNHN 1977.1253, MNHN 1977.1255, MNHN 1977.1262 GoogleMaps • 3 imago; Solu Khumbu District, Paiya [= Puiyan]; 27°38′41″ N, 86°43′40″ E (WGS 84); 8 Jun. 2003; Annemarie Ohler and Nicolas Pruvost leg.; MNHN 2003.3038 to MNHN 2003.3040 GoogleMaps .

Other material examined

NEPAL • 4 tadpoles; Ramechhap District ; 27°35′ N, 86°20′ E (WGS 84); 3084 m a.s.l.; Jun. 1997; local resident leg.; NHME (uncatalogued, field numbers 9705.10, 9705.15, 9705.21, 9705.22) GoogleMaps • 4 tadpoles; same locality as for holotype; Jun. 1997; local resident leg.; NHME (uncatalogued, field numbers 9705.73–76) GoogleMaps • 3 tadpoles; Dolakha District ; 27°40′ N, 86°14′ E (WGS 84); 2790 m a.s.l.; Jun. 1997; local resident leg.; NHME (uncatalogued, field numbers 9705.99, 9705.100, 9705.102) GoogleMaps .

Description (holotype)

Adult male, well preserved ( Fig. 7). Measurements are provided in Table 3. SVL 41.6 mm.

HEAD. Large and flat, wider than long ( HW /HL = 1.27); snout short and rounded; canthus rostralis distinct; nostril dorsolateral, just below canthal, midway between tip of snout and eye ( NSD / END = 1.10); loreal region slightly concave; eye large ( ED /HL = 0.43); internarial surface flat ( IND = 4.20); pupil vertical; interorbital space flat; tympanum and tympanic ring absent; tongue oval; choanae small, visible when viewed from below; vomerine and maxillary teeth absent; vocal sac absent; supratympanic fold distinct, extending from posterior corner of eye to supra-axillary region, associated with parotoid glands.

FORELIMBS. Robust; forearm of median length ( FAL / SVL = 0.29) and longer than hand ( HAL / SVL = 0.25), without spines; fingers slender, free of dermal fringes or web; all fingertips rounded, not dilated; relative finger lengths: 3> 4> 2> 1; subarticular tubercles absent; inner metacarpal tubercle flat and large; outer metacarpal tubercle indistinct; small black nuptial spines on dorsal and lateral surface of first and second fingers, and on inner side of third finger.

HINDLIMBS. Robust, moderately long ( TIBL /SVL = 0.43; FEL / TIBL = 1.00), heels are not in contact when folded at right angles to the body (see Fig. 8 and Supp. file 1L); foot same length as shank; tips of toes round; toes not webbed, relative lengths 4> 3> 5> 2> 1; subarticular tubercles absent; moderately large inner metatarsal tubercle, outer metatarsal tubercle absent.

SKIN. Body dorsally and laterally with distinct tubercles in life and in preservative, each tubercle with one or two keratinized tips, only a few tubercles with spines; few scattered tubercles on upper and lower mandibles; forehead and surfaces of lower arm and tarsus relatively smooth; tubercles present below and on supratympanic fold; upper arms and legs with spineless tubercles; throat and belly surface smooth; a pair of pectoral glands and a pair of axillary glands present on chest, pectoral glands slightly larger than axillary, pectoral glands covered by small black spines.

Coloration

In life, dorsal surface of head, body, and extremities brownish; a small dark brown band extending from anterior edge of eye to nostril and further to tip of snout, and from posterior edge of eye along supratympanic fold; irregular dark brown spots or transverse stripes on all limbs including fingers and toes; ventral and dorsal surface of lower forelimbs and dorsal surface of hands with small irregular creamy white warts; flanks light brown; throat, belly, and partly ventral surfaces of extremities light melon-yellow; belly covered by irregular gray-brown network.

In preservative, color of dorsal surfaces has changed from brown to gray and that of ventral surfaces from yellowish to grayish white.

Variation

Measurements of the type series are provided in Table 3. Color can vary substantially from light to dark brown and even to olive (Supp. file 1L–M).

Distribution

Occurs in mountain forests in high-montane areas of the drainage area of the Koshi basin, Northeastern Nepal, more specifically, along the Khumbu Himal and adjacent Makalu region between ca 2800 and 3900 m a.s.l. ( Fig. 1; Supp. file 1P). This species is known from the Sagarmatha and Koshi Zone, specifically the Dolakha District (Jiri), Ramechhap District, Solu Khumbu District (Lamjura La, Paiya, Surkie La, Taksindu), Bhojpur District (Salpa Pokhari), and in the Sankhuwasabha District. Eastern populations of this species that occur in the Bhojpur District (Salpa Pokhari), and in the Sankhuwasabha District are genetically distinct. This genetic differentiation supports the recognition of the eastern populations as a separate subspecies (see below).

Taxonomic remarks

In phylogenetic analyses, the new species belongs to a clade that branches with the clades previously identified in the genus Scutiger . The species distinction is supported by substantial molecular divergence from other Scutiger species, namely ≥ 11.1% uncorrected distance in the COI, ≥ 9.8% in the cytb, and ≥ 2.5% in the 16S gene (Supp. file 1D–F), by the resulting phylogenetic divergence ( Fig. 2), as well as by morphological differences ( Figs 4–5). Scutiger khumbu sp. nov. features two clearly divergent, fully allopatric mitochondrial lineages: one from the Khumbu Himal and the other from the Makalu region. These lineages show high mitochondrial sequence divergence, with uncorrected distance in COI, cytb, and 16S ranging 8.5–9.3%, 5.0–7.4%, and 2.4–2.6% (Supp. file 1G–I), respectively, private alleles at the nuclear genes bfib7 and ccnb2, allele sharing at rag1, and lack notable morphological differences. Bioacoustic variation in the new species remains to be investigated. Given their deep phylogeographic structure, but younger divergence (including some nuclear allele sharing) and the absence of clear phenotypic differences, we consider the lineage from the Makalu region as distinct subspecies of Scutiger khumbu sp. nov., namely Scutiger khumbu makalu subsp. nov.

Remarks on larvae

Eleven tadpoles of western populations of Scutiger khumbu sp. nov. at different stages ranging from 26 to 39 ( Gosner 1960) ( Fig. 9); LTRF: 3(2–3)/3(1–2), 3(2–3)/3(1–3), 3(2–3)/4(1–3), or 4(2–4)/4(1–3).