Nyctibatrachus manalari, Sonali Garg, Robin Suyesh, Sandeep Sukesan & Sd Biju, 2017

Sonali Garg, Robin Suyesh, Sandeep Sukesan & Sd Biju, 2017, Seven new species of Night Frogs (Anura, Nyctibatrachidae) from the Western Ghats Biodiversity Hotspot of India, with remarkably high diversity of diminutive forms, PeerJ 5 (3007), pp. 1-50 : 14-18

Nyctibatrachus manalari sp. nov.

urn:lsid:zoobank.org:act:9B10F3DA-07E4-4A78-B96B-C76C3C1578F6

Manalar Night Frog

( Figs. 1–4 ; Tables S1–S8)

Holotype. ZSI/WGRC/V/A/897, adult male, from Upper Manalar (09°34 29.31 N 77° 20 10.27 E, 1564 m), Periyar Tiger Reserve, Idukki district, Kerala state, India, collected by SDB and SG on 15 July 2016.

Paratypes. ZSI/WGRC/V/A/898–901, four adult males, collected along with the holotype. Other material studied. SDBDU 2015.2994, from the same locality as the type series, collected by SDB and SG on 0 5 July 2015, was used only for genetic identification of species. Etymology. The species is named after the type locality Upper Manalar in Periyar Tiger Reserve, from where the type series was collected. The specific name manalari is a noun in the genitive case.

Diagnosis. Nyctibatrachus manalari can be distinguished from known congeners by the following combination of morphological characters: (1) miniature-sized adult males (SVL 13.1–15.4 mm, N = 5); (2) head wider than long (male HW/HL ratio 115.7–135.6%, N = 5); (3) presence of weakly developed dorsolateral glandular folds separated by scattered granular projections; (4) third finger disc slightly wider than finger width (male FDIII 0.3– 0.4, FWIII 0.2–0.3, N = 5), with dorso-terminal groove and cover bifurcate distally; (5) fourth toe disc slightly wider than toe width (male TDIV 0.4–0.6, TWIV 0.2–0.3, N = 5), with dorso-terminal groove, cover bifurcate distally; (6) presence of single palmar tubercle; (7) foot webbing absent; (8) thigh nearly equal to shank length (male TL/SHL ratio 98.4–101.5%, N = 5); (9) thigh shorter than foot length (male TL/FOL ratio 84.7–90.7%, N = 5); (10) shank shorter than foot length (male SHL/FOL ratio 86.1–90.7%, N = 5); and (11) light reddish-brown ventral coloration in life.

Garg et al. (2017), PeerJ, DOI 10.7717/peerj.3007 15/50 Morphological comparison. Nyctibatrachus manalari species can be distinguished from all its congeners, expect N. anamallaiensis , N. athirappillyensis sp. nov., N. beddomii , N. deccanensis , N. kempholeyensis , N. minimus , N. minor , N. pulivijayani sp. nov., N. robinmoorei sp. nov., N. sabarimalai sp. nov. and N. webilla sp. nov., by its smaller snout-vent size, male SVL 13.1–15.4 mm (vs. larger, male SVL 18.1–76.9 mm), absence of webbing between toes (vs. present), and dorsal skin not prominently wrinkled and/or granular (vs. prominently wrinkled and/or granular). Nyctibatrachus manalari differs from N. athirappillyensis , N. deccanensis and N. kempholeyensis by absence of webbing between toes (vs. present); differs from N. minor by its dorsal skin without distinct dorsolateral glandular folds separated by an ‘X’ pattern on anterior half of back (vs. present); and differs from N. webilla by its third finger disc with dorso-terminal groove and cover bifurcate distally (vs. third finger without dorso-terminal groove).

Because of the comparable snout-vent size, Nyctibatrachus manalari could be confused with the previously known species N. anamallaiensis , N. beddomii and N. minimus , and three new species N. pulivijayani , N. robinmoorei and N. sabarimalai . However, N. manalari differs from N. anamallaiensis by its relatively larger male SL/HL ratio of 41.2–50%, N = 5 (vs. male SL/HL ratio of 29.4–34.9%, N = 5), eye length shorter than snout length, male EL/SL ratio 66.7–94.4%, N = 5 (vs. longer, male EL/SL ratio 125–140%, N = 5), fingers with dermal fringe (vs. absent), and light reddish-brown ventral coloration in life (vs. flesh or off white).

Nyctibatrachus manalari differs from N. beddomii by its dorsolateral glandular folds separated by scattered granular projections (vs. dorsal skin finely granular), forearm considerably shorter than hand length, male FAL/HAL ratio 58.8–73.5%, N = 5 (vs. nearly equal, male FAL/HAL ratio 93.3–103.7%, N = 10), relatively smaller male TL/FOL ratio of 84.7–90.7%, N = 5 (vs. male TL/FOL ratio of 91.4–107.8%, N = 10) and relatively smaller male SHL/FOL ratio of 86.1–90.7%, N = 5 (vs. male SHL/FOL ratio of 91.4–111.3%, N = 10).

Nyctibatrachus manalari differs from N. minimus by its dorsolateral glandular folds separated by scattered granular projections (vs. dorsal skin having faint and interrupted glandular folds), relatively smaller male HL/SVL ratio of 30.4–34.9%, N = 5 (vs. male HL/SVL ratio of 37.8–44.6%, N = 14), relatively smaller male TL/FOL ratio of 84.7–90.7%, N = 5 (vs. male TL/FOL ratio of 91.2–121.6%, N = 14) and relatively smaller male SHL/FOL ratio of 86.1–90.7%, N = 5 (vs. male SHL/FOL ratio of 97.1–125.5%, N = 14).

Nyctibatrachus manalari differs from N. pulivijayani by its head wider than long, male HW/HL ratio 115.7–135.6%, N = 5 (vs. nearly equal, male HW/HL ratio 98.3–102%, N = 5), relatively smaller male HL/SVL ratio of 30.4–34.9%, N = 5 (vs. male HL/SVL ratio 35.9–39.5%, N = 5), relatively larger male EL/HL ratio of 33.3–39.5%, N = 5 (vs. male EL/HL ratio of 25.9–32.7%, N = 5), thigh shorter than foot, male TL/FOL ratio 84.7–90.7%, N = 5 (vs. nearly equal, male TL/FOL ratio 95.5–106%, N = 5), shank shorter than foot, male SHL/FOL ratio 86.1–90.7%, N = 5 (vs. nearly equal, male SHL/FOL ratio 98.5–103%, N = 5), fingers with dermal fringe (vs. absent), and light reddish-brown ventral coloration in life (vs. flesh or off white).

Nyctibatrachus manalari differs from N. robinmoorei by its head wider than long, male HW/HL ratio 115.7–135.6%, N = 5 (vs. nearly equal, male HW/HL ratio 97.6–100%, N = 2), forearm shorter than hand length, male FAL/HAL ratio 58.8–73.5%, N = 5 (vs. longer, male FAL/HAL ratio 105.3–111.8%, N = 2), thigh nearly equal to shank, male TL/SHL ratio 98.4–101.5%, N = 5 (vs. longer, male TL/SHL ratio 127.5–130.8%, N = 2), thigh shorter than foot, male TL/FOL ratio 84.7–90.7%, N = 5 (vs. longer, male TL/FOL ratio 122.6–130.8%, N = 2), shank shorter than foot, male SHL/FOL ratio 86.1–90.7%, N = 5 (vs. nearly equal, male SHL/FOL ratio 96.2–100%, N = 2), fingers with dermal fringe (vs. absent), and light reddish-brown ventral coloration in life (vs. flesh or off white).

Nyctibatrachus manalari differs from N. sabarimalai by its head wider than long, male HW/HL ratio 115.7–135.6%, N = 5 (vs. head longer than wide, male HW/HL ratio

82.4–89.8%, N = 5), relatively smaller male HL/SVL ratio of 30.4–34.9%, N = 5 (vs. male HL/SVL ratio 38.3–41.5%, N = 5), relatively larger male EL/HL ratio of 33.3–39.5%, N = 5 (vs. male EL/HL ratio of 27.5–30.2%, N = 5), relatively smaller male FAL/HAL ratio of 58.8–73.5%, N = 5 (vs. male FAL/HAL ratio of 85.7–96.6%, N = 5), thigh shorter than foot, male TL/FOL ratio 84.7–90.7%, N = 5 (vs. nearly equal, male TL/FOL ratio 96.9–101.6%, N = 5), shank shorter than foot, male SHL/FOL ratio 86.1–90.7%, N = 5 (vs. nearly equal, male SHL/FOL ratio 98.4–100%, N = 5), fingers with dermal fringe (vs. absent), and light reddish-brown ventral coloration in life (vs. flesh or off white).

Description of holotype (measurements in mm). Adult male (SVL 13.8); head small, wider than long (HW 5.0, HL 4.2); snout rounded in dorsal and lateral view, its length (SL 1.9) longer than horizontal diameter of eye (EL 1.4); loreal region acute with indistinct canthus rostralis; interorbital space flat, wider (IUE 1.9) than upper eyelid (UEW 0.7) and internarial distance (IN 1.5); nostril closer to eye (EN 0.6) than the tip of snout (NS 0.9); tympanum indistinct; vomerine ridge weakly developed, bearing a few small teeth, at an angle of 70° to the body axis, closer to each other than choanae, shorter than the distance between them; tongue emarginated, bearing no medial lingual process. Forearm (FAL 2.0) shorter than hand length (HAL 3.4), finger length formula: I <II <IV <III, finger discs slightly wider compared to its width (FDI 0.2, FWI 0.1; FDII 0.3, FWII 0.2; FDIII 0.3, FWIII 0.2; FDIV 0.3, FWIV 0.2), finger disc with dorso-terminal groove, cover bifurcate distally; subarticular tubercles prominent, oval, single, all present; prepollex distinct, oval; single palmar tubercle, oval, distinct; nuptial pads present. Thigh length (TL 6.1) subequal to shank (SHL 6.2), and shorter than foot (FOL 7.2), relative toe lengths I <II <V <III <IV, toe discs slightly wider compared to toe width (TDI 0.4, TWI 0.3; TDII 0.4, TWII 0.3; TDIII 0.4, TWIII 0.3; TDIV 0.5, TWIV 0.3; TDV 0.4, TWV 0.3), toe disc with dorso-terminal groove, cover bifurcate distally; foot webbing absent; subarticular tubercles well developed, oval, single, all present; inner metatarsal tubercle present, oval; outer metatarsal tubercle weakly developed.

Skin of snout shagreened, upper eyelids with a few prominent glandular warts especially on the margins, presence of weakly developed dorsolateral glandular folds separated by scattered granular projections; sides of head, anterior and posterior parts of back, and upper and lower parts of flank shagreened with scattered glandular projections; subocular gland indistinct; upper surface of arms and legs shagreened with weakly developed granular projections; ventral surfaces smooth; a pair of prominent femoral glands present on the ventral surface of thighs ( Figs. 4 G and 4H).

Colour of holotype. In life. Dorsum reddish-brown, with a pair of faint orangish-brown longitudinal bands starting from behind the eyelids and extending up to the middle of dorsum, another orangish-brown stripe between the eyes demarcating a triangular orangish-brown patch on the snout ( Fig. 4 C); lateral sides of the head light greyish-brown with scattered white spots, upper eyelids dark brown; upper and lower parts of flank light orangish-brown with scattered minute white spots; forelimbs (including fingers) and hind limbs (including toes) light reddish-brown with dark brown transverse bands and scattered white spots. Ventral surfaces light reddish-brown in life ( Fig. 4 F), hand and foot lighter in colour than the chest and abdomen. In preservation. Dorsum and upper eyelids dark greyish-brown, with a pair of faint light brown longitudinal bands starting from behind the eyelids and extending upto the middle of dorsum, another light brown stripe between the eyes demarcating a triangular light brown patch on the snout; lateral sides of head light grey; forelimbs (including fingers) and hind limbs (including toes) light grey with dark grey transverse bands; anterior and posterior parts of flanks grey; ventral surfaces light greyish-white, hand and foot grey.

Variations. Morphometric data from five adult males, including the holotype, is given in Table S6. Overall, the colour and meristic characters of the paratypes are similar to the holotype. Colour in preservation. ZSI/WGRC/V/A/898: dorsum light brown in colour with dark grey spots; ZSI/WGRC/V/A/899 and ZSI/WGRC/V/A/901: dorsum darker grey in colour; ZSI/WGRC/V/A/900: dorsum lighter grey in colour.

Secondary sexual characters. Male (ZSI/WGRC/V/A/897), femoral glands present ( Figs. 4 G and 4H), nuptial pads weakly developed.

Vocalization. Male (ZSI/WGRC/V/A/897) of Nyctibatrachus manalari produced a single type of call. The calls had a single pulse and were not delivered in groups. A single call had the duration of 51.1 ms. Amplitude envelope of the call was characterized by a rise time of 6.7 ms, fall time of 34.7 ms. and the overall dominant frequency of 3.6 kHz with two broad peaks (Table S8; Figs. 3 F–3I).

Distribution and natural history. Nyctibatrachus manalari is currently known only from its type locality, which is located south of Palghat gap in the Western Ghats state of Kerala. Animals were found hiding under herbs and grasses growing on or at the edges of a large rocky area inside a primary evergreen forest patch. Calling males were located and recorded at night (between 19:00–21:00 h), but calls were also heard during the day (around 14:00 h). One of the calling males was found next to an egg clutch (eight eggs) deposited under the ground vegetation.

Figures

Figure 1 Morphometric differentiation of species using the discriminant function analyses. (A) Projection on factor plane first and second explaining 79.1 % of the variations among seven miniature-sized species. (B) Projection on factor plane first and second explaining 83.9 % of the variations among five medium-sized species. (C) Projection on factor plane first and second explaining 86.3 % of the variations among six large-sized species.

Figure 2 Holotype of Nyctibatrachus athirappillyensis sp. nov. (ZSI / WGRC / V / A / 891). (A) Dorsolateral view, in life. (B) Size (SVL 20.9 mm) in comparison to the Indian five-rupee coin (24 mm diameter). (C) Dorsal view, in life. (D) Dorsal surface of third finger disc, in preservation. (E) Dorsal surface of fourth toe disc, in preservation. (F) Ventral view, in life. (G) Femoral glands, in preservation. (H) Closeup of femoral glands after removal of skin showing multiple glands. (I) Lateral view of head, in preservation. (J) Ventral view of hand, in preservation. (K) Ventral view of foot, in preservation. (L) Schematic illustration of foot webbing.

Figure 3 Male advertisement calls of Nyctibatrachus athirappillyensis sp. nov. and Nyctibatrachus manalari sp. nov. (A – E) Nyctibatrachus athirappillyensis sp. nov. (A) 10 s segment. (B) 1 s segment showing part 1 (non-pulsatile) and part 2 (pulsatile) of a single call. (C) 0.1 s segment showing the part 2 of a single call. (D) 0.1 s segment showing the part 1 of a single call. (E) Spectrogram of 1 s call segment. (F – I) Nyctibatrachus manalari sp. nov. (F) 10 s segment. (G) 1 s segment. (H) 0.1 s segment showing a single non-pulsatile call. (I) Spectrogram of 1 s call segment.

Figure 4 Holotype of Nyctibatrachus manalari sp. nov. (ZSI / WGRC / V / A / 897). (A) Dorsolateral view, in life. (B) Size (SVL 13.8 mm) in comparison to the Indian five-rupee coin (24 mm diameter). (C) Dorsal view, in life. (D) Dorsal surface of third finger disc, in preservation. (E) Dorsal surface of fourth toe disc, in preservation. (F) Ventral view, in life. (G) Femoral glands, in preservation. (H) Close-up of femoral glands after removal of skin showing multiple glands. (I) Lateral view of head, in preservation. (J) Ventral view of hand, in preservation. (K) Ventral view of foot, in preservation. (L) Schematic illustration of foot webbing.