Raorchestes mindat, Köhler & Dost & Than & Ohler & Charunrochana & Chuaynkern & Chuaynkern & Geiss, 2025

Raorchestes mindat sp. nov.

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Fig. 6 View FIGURE 6

Holotype. CAS 234897 About CAS , an adult male collected between Hline Thoat village and Gyin Dwe village (20.9818, 93.9204; 1990 m a.s.l.), Kanpetlet township , Mindat District, Chin State, Myanmar, collected 11 September 2005 by A. K. Shein, T. Nyo, and L. Shein. Field tag number JBS-24974. GoogleMaps

Paratypes. CAS 234782–84 About CAS , Ovatmataung National Park (21.1925, 94.0497; 1530 m a.s.l.), Kanpetlet township, Mindat District, Chin State, Myanmar, collected 4 June 2004 by A. K. Shein, T. Nyo, and L. Shein. All paratypes are adult males GoogleMaps .

Diagnosis and comparisons. A species of the genus Raorchestes (our former “ R. sp. 1”) that differs from geographically and genetically relevant congeners of the Raorchestes parvulus group by the following combination of characters: (1) 16.75–18.36 mm SVL in males, n = 4; females unknown; (2) head about as long as wide (ratio HW/HL 0.94–1.14); (3) tympanum indistinct, supratympanic fold distinct; (4) webbing between Toes 1 and 2 vestigial; webbing formula for Toes 2, 3, 4 and 5: II 2–3½ III 2+–3½ IV 3¼–2 V; (5) tibiotarsal articulation reaching to level of posterior margin of eye when hind limb is stretched alongside of body; (6) nuptial pad small and white; (7) inner metatarsal tubercle rounded, outer metatarsal tubercle absent; (8) broad ridges along toes; (9) interorbital distance smaller than to subequal eye horizontal diameter (ratio IOD/EYD 0.80–1.04); and (10) nostril closer to tip of snout than eye.

Raorchestes mindat sp. nov. differs from its South-east Asian congeners by the following characteristics (condition for R. mindat in parentheses): Lectotype of Ixalus parvulus Boulenger, 1893 (i.e., MSNG 29838): SHL/ SVL 0.41 (vs. 0.44–0.51); inner metatarsal tubercle oval (vs. round); and head longer than wide (vs. about as long as wide). R. cangyuanensis : more toe webbing (vs. less toe webbing with webbing between Toes 1 and 2 vestigial); fingers and toes without lateral dermal ridges (vs. all fingers and toes with lateral dermal ridges on both sides); inner metatarsal tubercle oval (vs. rounded); and longer hind legs, THL/SVL mostly>0.45 (vs. mostly <0.45); hind legs reach to beyond anterior margin of eye when hind limb is stretched alongside of body (vs. to posterior border of eye). R. gryllus : a distinct calcar tubercle and a series of whitish tubercles along lower arm as well as on foot and tarsus present (vs. these structures absent). R. huanglianshan : a greater relative hand length, HNL/SVL>0.28 (vs. <0.28); fingers and toes without lateral dermal ridges (vs. all fingers and toes with lateral dermal ridges on both sides); and all ventral surfaces heavily suffused with dark pigment (vs. pale). R. longchuanensis : longer hind legs, THL/SVL mostly>0.45 (vs. mostly <0.45); inner metatarsal tubercle oval (vs. rounded); and a shorter first toe, ITL/HL mostly <0.2 (vs. mostly>0.2); and by having longer hind legs that reach to beyond anterior margin of eye when hind limb is stretched alongside of body (vs. to posterior border of eye). R. menglaensis : a shorter first toe, ITL/HL mostly <0.2 (vs. mostly>0.2); fingers and toes without lateral dermal ridges (vs. all fingers and toes with lateral dermal ridges on both sides); inner metatarsal tubercle oval (vs. rounded); and disc of first finger not distinctly enlarged relative to finger width (vs. distinctly enlarged). Raorchestes hillisi : outside of Toe 1 and both sides of Toe 2 without lateral dermal ridges (vs. all fingers and toes with lateral dermal ridges on both sides). Raorchestes malipoensis : a greater relative hand length, HNL/SVL>0.28 (vs. mostly <0.28); IOD/HL mostly>0.4 (vs. mostly <0.4); and by having longer hind legs that reach to beyond anterior margin of eye when hind limb is stretched alongside of body (vs. to posterior border of eye). Raorchestes rezakhani : fingers without lateral dermal ridges (vs. all fingers and toes with lateral dermal ridges on both sides); IOD/HL>0.45 (vs. <0.45); HW/HL about 1.5 (vs. about 1.0); inner metatarsal tubercle absent or indistinct (vs. distinct); and SL/HL>0.45 (vs. <0.45). R. tytthus and R. dulongensis : conspicuous white blotches present in groin and on thigh (vs. such white blotches absent); and by having longer hind legs that reach to beyond anterior margin of eye when hind limb is stretched alongside of body (vs. to posterior border of eye).

Description of the holotype ( Fig. 6 View FIGURE 6 ). Adult male, as indicated by lose wrinkled skin of vocal sac in throat region and presence of vocal slits; SVL 18.2 mm; habitus robust; head broad, slightly wider than long, ratio HW/ HL 1.14; snout nearly rounded in dorsal view, projecting beyond lower jaw, rounded in profile; nostril closer to tip of snout than eye; canthus rostralis rounded, loreal region slightly concave; eyes moderately large (EYD 2.45 mm) and protruding, pupil horizontal; ratio EYD/HL 0.44; IOD (2.34 mm) greater than width of upper eyelid (1.26 mm); tympanum indistinct, ratio TYD/EYD 0.44; vomerine teeth absent; tongue fleshy, rounded, without notch; supratympanic fold distinct, from posterior corner of eye to above insertion of arm. Numerous minute pointed tubercles on upper eyelid and on dorsum. Forelimbs fairly robust (FHL 8.87 mm); relative finger lengths: I <II <IV <III, tips of all four fingers expanded into discs with circum-marginal grooves; discs of outer two fingers larger than those of Fingers I and II; all fingers with lateral dermal ridges on both sides; subarticular tubercles distinct, rounded; supernumerary tubercles absent; no webbing between fingers; inner (i.e., thenar) and outer (i.e., palmar) metacarpal tubercle oval, about subequal in size; nuptial pad small and white on dorsal surface of the first finger. Foot relatively robust (FL 7.06 mm), shorter than shank length (SHL 8.4 mm); relative toe lengths: I <II <III <V <IV; tips of toes with discs having circum-marginal grooves, largest toe discs slightly smaller than largest finger discs; all toes with lateral dermal ridges on both sides; subarticular tubercles distinct, rounded; supernumerary tubercles absent; webbing between Toes 1 and 2 vestigial; webbing formula for Toes 2, 3, 4 and 5: II 2–3½ III 2+–3½ IV 3¼–2 V; inner metatarsal tubercle oval, outer metatarsal tubercle absent. Tibiotarsal articulation reaching to level of posterior margin of eye when hind limb is stretched alongside of body.

Coloration after almost 20 years preservation in 70% ethanol was recorded as follows: Dorsal surfaces Walnut Brown (color 27) with indistinct Brownish Olive (276) transverse bars on limbs and an X-shaped mark as well as lines on dorsum; also a distinct Brownish Olive (276) interorbital bar present; upper eyelid Dark Neutral Gray (299); all ventral surfaces Light Buff (2), heavily suffused with Clay Color (18).

Genomic characterization. Whole genome sequencing yielded 363,651,538 Illumina short reads with a total data size of 124.8 Gb. Genome assembly resulted in a highly fragmented and incomplete genome of 366 Mb in size. The assembly consits of 510,225 contigs the largest contig being 523,631 bp and an N50 of 675 bp. The BUSCO analysis resulted in 128 recovered complete BUSCOs representing a completeness of 2.4% (complete: 2.4% [single-copy: 2.3%, duplicates: 0.1%], fragmented: 0.5%, missing: 97.1%, n: 5310). The mitochondrial genome was assembled into one linear contig with a total length of 15,960 bp (Genbank accession No. PV077346). A total of 37 genes could be annotated, including all 13 protein coding genes, 2 rRNAs and 22 tRNAs. Pairwise alignment to the complete mitochondrial genome of Zhangixalus chenfui (GenBank accession No. NC_062878.1) revealed a pairwise identity of 78.76%. The raw genomic data for CAS 234897 can be accessed from the Sequence Read Archive (SRA) under SRR31929897.

Variation. The paratypes agree well with the holotype in general appearance, morphometrics (see Table 5 View TABLE 5 ), and coloration. However, in some paratypes the largest toe discs are about subequal in size as largest finger discs.

Etymology. The species name “ mindat ”, a noun in apposition, refers to the Mindat Township, Chin State, Myanmar, where the holotype of this species was collected.

Natural history notes. According to the CAS catalogue, the holotype was discovered on a bush at about 60 cm above ground level at 19:45 h on 11 September 2005 (air temperature was 21.2°C and the relative humidity 88%). The paratypes ( CAS 234782–84 About CAS ) were collected at 11:03 h on 4 June 2004 when the air temperature was 24.2°C and the relative humidity 34%.

Geographic distribution and conservation. Raorchestes mindat is currently known from two localities in central Myanmar ( Fig. 9 View FIGURE 9 ). At this point this species is only known from the four specimens that constitute the type series and we therefore classify it as Data Deficient according to the IUCN categories ( IUCN 2012).