Amolops adicola, Patel & Garg & Das & Stuart & Biju, 2021

Patel, Naitik G., Garg, Sonali, Das, Abhijit, Stuart, Bryan L. & Biju, S. D., 2021, Phylogenetic position of the poorly known montane cascade frog Amolops monticola (Ranidae) and description of a new closely related species from Northeast India, Journal of Natural History 55 (21 - 22), pp. 1403-1440 : 1424-1434

Amolops adicola sp. nov.

http://zoobank.org/ urn:lsid:zoobank.org:act:9968D3D8-9846-4BF5-8CA2-AE0CF5DE71EC Adi cascade frog

( Figures 1 , 2 , 7–14 ; Tables 1–3, S1–S2; Call S1)

Holotype

BNHS 6121 , an adult female, from Adi hills adjoining the basin of Mossing River, located between Tuting and Jengging (28.776°N, 94.768°E, elevation 515 m asl), Upper Siang district, Arunachal Pradesh State, India, collected by Abhijit Das, on 9 October 2018.

Paratypes

BNHS 6122 and BNHS 6123 , two adult males, and BNHS 6124 , an adult female, collected along with the holotype; BNHS 6125 , an adult female, from Dainakorong Stream, near Renging (28.094° N, 95.268° E, elevation 356 m asl), East Siang district , Arunachal Pradesh State, India, collected by Abhijit Das, on 2 October 2018 .

Referred specimen

SDBDU 2018.4102 , an adult male, collected along with the holotype .

Etymology

The species name is derived from ‘Adi’ (after Adi hills and the Adi tribe that inhabits the region where the type series was collected) and Latin ‘cola’ (meaning inhabiting or dwelling in). The species epithet adicola is treated as an invariable noun in apposition to the generic name.

Diagnosis

Amolops adicola sp. nov. can be diagnosed from known congeners by having the following combination of morphological characters: medium adult size (female SVL 62–72 mm, male SVL 39–47 mm); dorsum light brown; lateral surfaces of the head blackish brown from the snout tip (narrower) to posterior margin of the axilla; a silvery-white stripe extending along the upper lip to the posterior margin of the axilla; presence of vomerine ridge with teeth between choanae, closer to each other than to choanae; tympanum rather more distinct in preservative than in life; dorsal skin smooth with scattered glandular projections (conspicuous in life and less conspicuous in preservation); presence of dorsolateral folds, without spinules; inner metatarsal tubercle oval, outer metatarsal tubercle absent; supernumerary tubercles absent; and two external subgular vocal sacs in males ( Figures 8–11 ).

Genetic relationship

Amolops adicola sp. nov. is a member of the A. monticola group and shows a wellsupported sister relationship with A. monticola ( Figure 1 ). Within the A. monticola group, it differs from all other genetically known members by uncorrected pairwise genetic distances of ≥ 4.3% for 16S, ≥ 6.1% for COI and ≥ 7.0% for ND2.

Description of holotype (measurements in mm)

A medium-sized adult female (SVL 62.4), body rather robust; head longer than wide (HL 19.9; HW 18.0; MN 16.4; MFE 12.3; MBE 6.9); outline of the snout rounded in dorsal, ventral and lateral views, its length (SL 8.3) longer than horizontal diameter of eye (EL 6.5); loreal region nearly vertical, with indistinct canthus rostralis; interorbital space flat, wider (IUE 6.0) than upper eyelid width (UEW 4.1) and internarial distance (IN 5.8); nostril oval, closer to tip of snout (NS 3.1) than eye (EN 4.2); tympanum rather distinct (TYD 2.5), 38.5% of eye diameter (EL 6.5) and nearly equal to the distance from tympanum to eye (TYE 2.6); pineal ocellus present between eyes; vomerine ridge present, bearing four large teeth, at an angle of 60° relative to the body axis, closer to each other than choanae, longer than the distance between them; tongue large, rounded to cordate, emarginate, lingual papilla absent; supratympanic fold rather indistinct ( Figures 8–10 ). Arms moderately long, forearm length (FAL 12.6) shorter than hand length (HAL 17.9); relative length of fingers I <II <IV <III (FL I 7.5, FLII 9.1, FLIII 13.0, FLIV 9.7), tips of fingers enlarged into discs, moderately wide compared to finger width (FDI 1.5, FWI 0.7; FDII 2.2, FWII 0.7; FDIII 3.0, FWIII 0.9; FDIV 2.8, FDIV 0.9), finger discs with circummarginal grooves; dermal fringe present on fingers; webbing absent between fingers; subarticular tubercles rather prominent and rounded, formula 1, 1, 2, 2; one supernumerary tubercle each on the base of all fingers ( Figure 10 ); two metacarpal tubercles, oval. Hind limbs long, heels overlapping when legs at right angle to the body; thigh (TL 34.2) shorter than shank (SHL 39.8) and longer than foot (FOL 32.1); distance from base of tarsus to tip of toe IV (TFOL 51.8); tibiotarsal articulation reaching well beyond snout tip; relative length of toes I <II <V <III <IV; toe tips dilated with prominent discs (TDI 1.5, TWI 0.7; TDII 2.2, TWII 0.7; TDIII 3.0, TWIII 0.9; TDIV 2.8, TWIV 0.9; TDV 1.9, TWV 0.8), toe discs with circummarginal grooves, discs slightly smaller on toes I and IV; dermal fringe on the preaxial side of toe I and postaxial side of toe V; foot webbing large: I1–1II1–1+III1–1⅓IV1⅓–1V, extends well beyond the third subarticular tubercle on either side of toe IV, with narrow extension towards the base of the disc; subarticular tubercles prominent, all present, oval; inner metatarsal tubercle prominent (IMTL 2.1), oval; outer metatarsal tubercle absent; supernumerary tubercles absent ( Figure 10 ).

Skin of dorsum smooth to shagreened with scattered tubercles (more conspicuous in life and inconspicuous in preservation), lateral surfaces of the head smooth to shagreened, except with a few indistinct tubercles present on the tympanic region; groin and fore- and hind limbs (including fingers and toes) smooth to shagreened; supratympanic fold indistinct; flanks and groin smooth; dorsolateral folds distinct, from rear of the upper eyelid to almost the vent; posterior parts of thigh and cloacal region granular; two rictal glands, anterior gland continuous with the upper lip. Ventral surfaces smooth ( Figure 10 ).

Colour in life. Dorsum light brown with scattered brown spots, a narrow brown streak from the tip of snout to the anterior end of eye, and a broad brown streak from the posterior end of eye to the axilla, including tympanic region; flank and groin light brown with creamy-white spots; rictal glands silvery white, anterior one from near the snout on the upper jaw to axilla, and a small posterior one nearer to the arm insertion; upper half of iris golden brown, lower half darker; dorsal surface of limbs lighter than dorsum with scattered brown irregular spots; anterior surfaces of thigh yellowish brown with lightbrown reticulations. Ventral surfaces of throat, chest and belly creamy white; throat, chest and anterior part of belly with greyish spots; fore- and hind limbs flesh-red without markings; margins of the jaws with thin blackish-brown bands; nuptial pad white; foot webbing light grey with dark-grey spots ( Figures 8 and 9 ). Colour in preservation. Dorsum greyish brown, with small scattered blackish spots, especially on anterior half; posterior part of thighs light brown with faint light-grey reticulations; fore- and hind limbs (including fingers) greyish brown with scattered and irregular blackish markings or cross-bands; lateral surfaces of the head dark brown, especially the tympanic region; rictal glands silvery white; margins of upper and lower jaw with thin blackish bands; flank and groin light brown with scattered creamy-white spots. Ventral surfaces of throat, chest and belly creamy white; throat, chest and anterior part of abdomen with scattered light-brown spots; ventral surfaces of fore- and hind limbs light grey with light-brown spots on margins; webbing greyish brown ( Figure 10 ).

Description of paratype, BNHS 6123 (measurements in mm)

A medium-sized adult male (SVL 44.9), body rather robust; head longer than wide (HL 16.3; HW 13.3); outline of the snout rounded in dorsal, ventral and lateral views, its length (SL 6.4) longer than horizontal diameter of eye (EL 5.3); loreal region nearly vertical, with indistinct canthus rostralis; interorbital space flat; nostril oval, closer to tip of snout (NS 2.3) than eye (EN 3.3); tympanum rather distinct (TYD 2.9), 54.7% of eye diameter (EL 5.3), and shorter than the distance from tympanum to eye (TYE 1.6); pineal ocellus present between eyes. Arms moderately long, forearm length (FAL 9.6) shorter than hand length (HAL 14.3); relative length of fingers I <II <IV <III; tips of fingers enlarged into discs, moderately wide compared to finger width, finger discs with circummarginal grooves; dermal fringe present on fingers; webbing absent between fingers; subarticular tubercles rather prominent and rounded ( Figure 11 ); two metacarpal tubercles, oval. Hind limbs long, heels overlapping when legs at right angle to the body; thigh (TL 25.0) shorter than shank (SHL 29.3) and longer than foot (FOL 24.8); distance from base of tarsus to tip of toe IV (TFOL 38.5); tibiotarsal articulation reaching well beyond snout tip; toe discs with circummarginal grooves, discs slightly smaller on toes I and IV; dermal fringe on the preaxial side of toe I and postaxial side of toe V; foot webbing large: I1–1II1–1III1–1+IV1+–1 V, extends well beyond the third subarticular tubercle on either side of toe IV, with narrow extension towards the base of the disc; subarticular tubercles prominent, all present, oval; inner metatarsal tubercle prominent (IMTL 1.9), oval; outer metatarsal tubercle absent; supernumerary tubercles absent ( Figure 11 ).

Skin of dorsum shagreened with scattered tubercles, lateral surfaces from head to groin, and fore- and hind limbs shagreened; supratympanic fold indistinct; flanks and groin smooth; dorsolateral folds distinct, from rear of the upper eyelid to almost the vent; posterior parts of thigh and cloacal region prominently granular; two rictal glands, anterior gland continuous with the upper lip. Ventral surfaces smooth ( Figure 11 ).

Colour in life. Dorsum greyish brown with scattered brown spots, a narrow brown streak from the tip of snout to the anterior end of eye; flank and groin light brown with creamy-white or light-grey spots; rictal glands silvery white, anterior one from near the snout on the upper jaw to axilla, and a small posterior one nearer to the arm insertion; dorsal surface of limbs lighter than dorsum with faint cross-bands; anterior surfaces of thigh orangish brown. Ventral surfaces creamy white; fore- and hind limbs flesh-red without markings; foot webbing light grey with dark-grey spots ( Figure 9 ). Colour in preservation. Dorsum greyish brown, with small scattered blackish spots, especially on anterior half; fore- and hind limbs greyish brown with scattered and irregular blackish cross-bands; flank and groin light brown. Ventral surfaces of throat, chest and belly greyish white ( Figure 11 ).

Morphological variations

Morphometric data from the type specimens (males, N = 3; females, N = 3), including the holotype, are provided in Table 2. The overall morphology of the paratypes is similar to the holotype with slight variations in skin texture, colour and markings. BNHS 6125 (female): anterior part of dorsum shagreened, and posterior half sparsely granular; anterior parts of thigh light brown with cream reticulations; ventral surfaces, especially throat and chest, with prominent light-brown spots. BNHS 6124 (female), in life: flanks light orangish ( Figure 8 ); in preservative: posterior half of dorsum and posterior parts of thigh granular. BNHS 6122 (male): posterior half of dorsum and the cloacal region, relatively more granular; ventral surfaces without prominent spots, other than minute speckles. SDBDU 2018.4102 (male), in life: margins of throat, flanks and posterior parts of thigh bright orange ( Figure 8 ).

Secondary sexual characters

Female (BNHS 6125): ova, creamy white without pigmentation (diameter 1.6–1.9 mm, N = 20). Male (BNHS 6123): loose skin on either side of the throat in calling males and smooth nuptial pad on finger I.

Morphological comparison

Amolops adicola sp. nov. differs from all other Amolops , except those in the A. monticola group, by its distinctive dorsolateral folds (vs absent) and lateral surfaces of the head dark blackish brown with a light-coloured stripe (usually silvery white or golden-creamy white) extending from the upper lip to the shoulder (vs absent).

Within the A. monticola group, Amolops adicola sp. nov. is genetically and morphologically close to A. monticola ; however, it differs from A. monticola by relatively larger adult male size, SVL 44–47 mm, N = 3 (vs smaller, male SVL 38–40 mm); nostril closer to snout than eye, NS/EN ratio 0.67–0.85 (vs nearly equidistant, NS/EN ratio 0.96–1.09); snout length relatively longer than eye diameter in males, SL/EL ratio 1.16–1.25 (vs nearly equal, SL/EL ratio 1.0–1.04); absence of metacarpal tubercles on hand (vs presence of two elongate metacarpal tubercles); flank light brown or orangish (vs greyish brown with bluish or yellowish tinge); relatively well-developed dorsolateral folds (vs weakly developed and inconspicuous in preservation); presence of circummarginal groove on tip of finger I (vs weakly developed); and dorsal skin in males smooth to shagreened, occasionally with sparsely granular posterior part of the dorsum (vs shagreened to sparsely or prominently granular). Furthermore, a Welch two-sample t-test of morphometric data revealed that the new taxon differs significantly from A. monticola with respect to sizecorrected characters such as EL, NS, FAL, FWI, IN, HW, EN and TL (all p values <0.05; Table 3). In the PCA, A. adicola sp. nov. populations clustered separately from A. monticola populations along the ordination of principal components (PC) 1 and 2 ( Figure 12 ), which together explained 60.03% of the total variation. PC1 accounted for 38.3% of the variation in the morphometric data, with the following variables contributing the most: EL, FAL, FWI, IN, TL, NS, SHL, HL and HW, in that order. PC2 accounted for an additional 22% of the variation in the data, with the following variables contributing the most: HAL, EN, TFOL, FOL, SL, TYE and TYD. PC3 accounted for another 12.9% of the variation, with the following variables contributing the most: TDIV, IMTL, SL and FOL; and PC4 accounted for an additional 7.8% of the variation, with the following variables contributing the most: FDI, TYD, HAL and HL. Altogether, the new species was found to be distinct and well differentiated from its sister species based on morphometric characters.

Further, A. adicola sp. nov. differs from other members of the A. monticola group ( A. akhaorum , A. bellulus , A. compotrix , A. cucae , A. daorum , A. mengdingensis , A. iriodes , A. vitreus and A. wenshanensis ) by its light- to dark-brown (or shades of brown) dorsal colouration (vs green). Among the green-coloured members, A. adicola sp. nov. differs from A. akhaorum specifically also by the absence of black-coloured tubercles on dorsum (vs present); presence of nuptial pad on finger I in males (vs absent); and absence of distinct cross-bands on limbs (vs more prominent). It differs from A. bellulus by the presence of vocal sac in males (vs absent); and presence of circummarginal groove on the tip of finger I (vs absent). It differs from A. compotrix by its larger adult size, male SVL 44–47 mm, female SVL 62–72 mm (vs smaller, male SVL 31–43 mm, female SVL 56– 57 mm); and absence of outer metatarsal tubercle (vs present). It differs from A. cucae by the presence of pineal ocellus (vs absent); and absence of outer metatarsal tubercle (vs present). It differs from A. daorum by larger adult size, male SVL 44–47 mm, female SVL 62–72 mm (vs smaller, male SVL 32–39 mm, female SVL 53–57 mm); presence of vomerine teeth (vs absent); and absence of glandular white spots on flank (vs present). It differs from A. mengdingensis by the presence of pineal ocellus (vs absent); nuptial pad smooth (vs velvety); and presence of supernumerary tubercles on hand (vs absent). It differs from A. iriodes by larger adult size, male SVL 44–47 mm, female SVL 62–72 mm (vs smaller, male SVL 38–40 mm, female SVL 62 mm); presence of nuptial pad on finger I in males (vs absent); and absence of black tubercles on dorsum (vs present). It differs from A. vitreus by the presence of pineal ocellus (vs absent); and absence of outer metatarsal tubercle (vs present). It differs from A. wenshanensis by larger adult size, male SVL 44–47 mm, female SVL 62–72 mm (vs smaller, male SVL 35–40 mm, female SVL 43–46 mm); and presence of supernumerary tubercles on hand (vs absent).

Among the species with brown (or shades of brown) dorsum, Amolops adicola sp. nov. differs from A. aniqiaoensis by the outline of its snout rounded in ventral view (vs subovoid to subelliptical);head longer than wide (vs equal); and margins of dorsolateral folds and posterior part of the dorsal skin shagreened (vs with sharp spinular projections). It differs from A. archotaphus by the presence of circummarginal groove on the tip of finger I (vs absent); and absence of outer metatarsal tubercle (vs present). It differs from A. chakrataensis by head longer than wide (vs wider than long); the outline of snout rounded in ventral view (vs obtusely pointed); and the presence of supernumerary tubercles on hand (vs absent). It differs from A. chunganensis by larger adult size, male SVL 44–47 mm, female SVL 62–72 mm (vs smaller, male SVL 34–40 mm, female SVL 44–54 mm); and absence of distinct cross-bands on limbs (vs more prominent). It differs from A. kohimaensis by the absence of prominent dorsal spots (vs presence of blackish-brown spots);absence of distinct cross-bands on limbs (vs more prominent); absence of extensive dorsal spinules in males under breeding conditions (vs present); and presence of circummarginal groove on tip of finger I (vs weakly developed). It differs from A. nyingchiensis by relatively smaller adult male size, SVL 44–47 mm (vs larger, SVL 53–59 mm); absence of tooth-like projections on anteromedial edge of mandible (vs present); absence of distinct cross-bands on limbs (vs more prominent); and presence of vocal sac in males (vs absent). It differs from A. tuanjieensis by larger adult size, male SVL 44–47 mm, female SVL 62–72 mm (vs smaller, male SVL 39–41 mm, female SVL 56–61 mm); dorsum light- or dark-brown (vs brownish red); lateral surfaces light brown or orange (vs green); nuptial pad smooth (vs velvety); and absence of distinct cross-bands on limbs (vs more prominent). It differs from another provisionally placed member of the group, A. gerbillus , by eye length shorter than snout length (vs eye longer than snout length); rather distinct dorsolateral fold (vs indistinct); dorsum light brown to dark brown without prominent reticulations or blotches (vs reddish brown with light-greyish-yellow reticulations); dorsal skin smooth, occasionally with spinular projections on posterior part of dorsum (vs dorsum finely granular throughout); lateral surfaces shagreened without prominent glands (vs with prominent glandular projections); and foot webbing large, extending above the third subarticular tubercle on either side of toe IV, with narrow extension up to the base of the disc (vs fully webbed, up to the base of the discs).

Vocalisation

Amolops adicola sp. nov. males produce a single type of call with pulsatile temporal structure. Calls are not delivered in long call groups and have very short intervals, making them appear continuous. A typical call showed a duration of 485.2 ms; the amplitude envelope was characterised by a rise time of 479.9 ms and fall time of 5.3 ms, comprising nine pulses that were delivered at a rate of 17.1 pulses/second; and the spectrum was characterised by three broad frequency peaks with an overall dominant frequency of 3.3 kHz. The call also showed slight frequency modulation across the pulses ( Figure 13 ).

Distribution and natural history

Amolops adicola sp. nov. is currently known only from its type locality (Mossing) and surrounding regions in Adi hills (historically known as Abor hills) of Arunachal Pradesh State, India ( Figure 7 ) . The types were collected from low elevations ranging broadly between 350 and 520 m asl. We have observed a similar-looking population of frogs in Subansiri River basin, inhabiting rivers such as Ranganadi, Pare, Pati and Lichi in the Lower Subansiri district of Arunachal Pradesh State, India . These localities are 130–150 km straight west from the type locality. Further studies are required to confirm the identity of the Subansiri population .

This species is predominantly found in open riverine landscapes and human-inhabited rural areas. During the month of October, calling activities were initiated as early as 15:00 hrs. Calling individuals were located inside thick vegetation on roadside slopes facing the Mossing River by around 17:00 hrs and the vocalisation continued until 22:00 hrs. Males were mostly observed on tree saplings, fern fronds and banana plants in and around the cultivated land. During the peak activity period, males were largely located among exposed roadside boulders below the slopes, in close vicinity of water ( Figure 14 ). Males have paired, translucent external vocal sacs. At the time of peak calling activity (~19:00 hrs), we recorded humidity of 79.6%, dry bulb temperature of 19°C and wet bulb temperature of 14.5°C.

Amplecting pairs were observed from 19:30 hrs onward. Amplexus was axillary and most of the amplecting pairs were found among cobbles and boulders on the river bed, about 5 to 15 m away from water. No calling activity was observed on the river bed, suggesting that amplexus likely occurs in the adjoining forested slopes after which the female carries the male towards the river for egg-laying. This was the only species found in breeding aggregation in the landscape during the month of October. Among gravid females, egg mass was visible externally. One female collected at 23:00 hrs had an empty belly with flaccid lateral skin suggestive of a recent egg-laying event. We observed roadkilled females with unpigmented eggs on a road that divided the forested slope from the river bed.

About 15 males and four females were observed within a period of 2 hrs. Calling individuals were recorded at Mossing. We heard similar calls from other rivers such as Siyom , approximately 65 km south of the type locality ( Mossing ), on the way to Jengging (28.422°N, 95.086°E, 566 m), and Simang River (28.444°N, 95.877°E, 512 m), perhaps suggesting a widespread distribution of the species in similar niches within the landscape . This frog is considered a local delicacy, and we have observed bundles of smoked frogs being sold in the main Pasighat market. The species is locally called Juri (= stream) Tatik (= frog).

Figures

Figure 1. Bayesian consensusphylogram for 167 taxa representing members of the genus Amolopsand five outgroup species, based on 2001 bp of concatenated mitochondrial DNA (16S, COI, and ND2 genes). Voucher numbers and associated details are referenced in Table S1. Bayesian posterior probabilities (BPP) and RAxML bootstrap support (BS) values>50% are denoted above and below the branches, or separated by an oblique (/) mark, respectively.Black vertical bars beside the terminal nodes indicate Amolops species recognised based on Bayesian and ML inferences; grey bars and open rectangles indicate putative species delimited in the bPTP analysis with support values of>90% or <90%, respectively. The genus comprises eight major species groups following Wu et al. (2020), as indicated with coloured bars on the extreme right and corresponding circles on the internal and terminalnodes.Four subgroups are observed within the focal Amolops monticola group. Illustrations representing species groups were prepared based on published photographs.

Figure 2. (a) The type localities of all known members of the Amolops monticola species group. Geographical coordinates and their source information are referenced in Table S2. Illustrations for species are prepared based on type images or subsequently published photographs. (b) The number of A. monticola group species originally described from different Asian countries, based on their type localities. (c) The number of A. monticola group species currently recognised to occur in different countries. An asterisk (*) after the species name indicates a provisionally grouped species.

Figure 7. (a) Distribution map of all known members of the Amolops monticola species group found in India; (b) inset rectangle enlarged to show the type locality of Amolops monticola ‘Darjeeling’ and the rediscovered locality in south Sikkim. An asterisk (*) after the species name indicates members whose type locality is in India. A question mark (?) indicates a doubtful record. Geographical coordinates and their source information are referenced in Table S2.

Figure 8. Amolops adicola sp. nov. in life: (a) dorsolateral view (holotype, BNHS 6121, female); (b) dorsolateral view of amplected pair (paratype, BNHS 6125, female, male not preserved); (c) dorsolateral view of amplected pair (paratype, BNHS 6124, female; paratype, BNHS 6122, male).

Figure 9. Holotype and paratypes of Amolops adicola sp. nov. in life (photographed under captive conditions): (a–d) holotype (BNHS 6121, female): (a) dorsal view; (b) ventral view; (c) posterior view of thighs; (d) dorsolateral view of head; (e, f) paratype (BNHS 6123, male): (e) dorsal view; (f) ventral view. Photographs: AD.

Figure 10. Holotype (BNHS 6121, female) of Amolops adicola sp. nov. in preservation: (a) dorsal view; (b) ventral view; (c) lateral view of head; (d) front view of the snout showing light-coloured snout with dark spots; (e) ventral view of hand; (f) ventral view of foot; (g) schematic illustration of webbing on foot.

Figure 11. Paratype (BNHS 6123, male) of Amolops adicola sp. nov. in preservation: (a) dorsal view; (b) ventral view; (c) dorsal view of head; (d) ventral view of hand; (e) dorsal view of hand showing nuptial pad on finger I; (f) illustration of tip morphology on finger I; (g) illustration of tip morphology on finger III; (h) ventral view of foot; (i) schematic illustration of webbing on foot.

Figure 12. (a) Plot of first two principal components (PC1 and PC2) from principal component analysis based on morphometric data for Amolops adicola sp. nov. and A. monticola; (b–e) total contributions of the first four principal components: (b) PC1 (38.3% variance); (c) PC2 (22% variance); (d) PC3 (12.9% variance); (e) PC4 (7.8% variance). The red dashed line on the histograms indicates the expected average contribution.

Figure 13. Male advertisement calls of Amolops adicola sp. nov.: (a) 10 s oscillogram showing a call group comprising pulsatile calls; (b) 0.5 s oscillogram for a single call; (c) 0.1 s oscillogram for a call segment; (d) 0.5 s spectrogram for a single call.

Figure 14. (a) Habitat at the collection locality for topotypes of Amolops monticola in south Sikkim; (b) habitat at the holotype locality of Amolops adicola sp. nov. in Arunachal Pradesh.Thumbnail images of the species indicate the site of collection.