Minervarya chilapata, Ohler, Annemarie, Deuti, Kaushik, Grosjean, Stéphane, Paul, Subhadip, Ayyaswamy, Anand Kumar, Ahmed, Firoz & Dutta, Sushil K., 2009

Ohler, Annemarie, Deuti, Kaushik, Grosjean, Stéphane, Paul, Subhadip, Ayyaswamy, Anand Kumar, Ahmed, Firoz & Dutta, Sushil K., 2009, Small-sized dicroglossids from India, with the description of a new species from West Bengal, India, Zootaxa 2209, pp. 43-56 : 45-50

Minervarya chilapata sp. nov.

Holophoront. ZSI A 10784 , adult male (SVL 20.3 mm), collected on 29 July 2007 by Subhadip Paul and Kaushik Deuti.

Onymotope. Beside rainwater pools alongside forest road inside Mendabari Beat of Chilapata Reserve Forest (26°36’N, 89°24’E), Jalpaiguri District, West Bengal State, India.

Paratopophoronts. ZSI A 10785 —A 10793, 7 adult males and 2 adult females, collected by Anand Kumar Ayyaswamy and Kaushik Deuti at the same locality as the holophoront.

Description of holophoront. ZSI A 10784 , adult male ( Fig. 1 ).

(A) Size and general aspect. (1) Specimen of small size (SVL 20.3 mm), body moderately slender.

(B) Head. (2) Head of moderate size, longer (HL 7.9 mm) than wide (HW 6.5 mm; MN 7.24 mm; MFE 5.79 mm; MBE 3.16 mm), convex. (3) Snout pointed, protruding, its length (SL 3.44 mm) longer than horizontal diameter of eye (EL 2.92 mm). (4) Canthus rostralis rounded, loreal region concave, angle to upper surface of snout rather vertical. (5) Interorbital space convex, larger (IUE 1.94 mm) than upper eyelid (UEW 1.88 mm) and narrower than internarial distance (IN 2.01 mm); distance between front of eyes (IFE 4.21 mm) three quarter of distance between back of eyes (IBE 5.64 mm). (6) Nostrils rounded, with flap of skin laterally, closer to eye (EN 1.56 mm) than to tip of snout (NS 1.62 mm). (7) Pupil indistinct. (8) Tympanum ( TYD 1.36 mm) poorly distinct, rounded; less than half of eye diameter, tympanum-eye distance (TYE 0.71 mm) half its diameter. (9) Pineal ocellus present, between anterior borders of eyes. (10) Vomerine ridge absent. (11) Tongue rather large, cordate, emarginate; median lingual process absent; tooth like projections on maxilla absent.

(C) Forelimbs. (12) Arm short, rather strong (FLL 4.41 mm), shorter than hand (HAL 4.67 mm), not enlarged. (13) Fingers short, thin (TFL 2.72 mm). (14) Relative length of fingers, shortest to longest: I <II <IV <III. (15) Tips of fingers bluntly rounded, not enlarged. (16) Fingers without dermal fringe; webbing absent. (17) Subarticular tubercles prominent, rounded, single, all present. (18) Prepollex oval, distinct; a single round, indistinct palmar tubercle; supernumerary tubercles absent.

(D) Hindlimbs. (19) Shanks three times longer (TL 9.9 mm) than wide (TW 3.05 mm), longer than thigh (FL 8.5 mm), but shorter than distance from base of internal metatarsal tubercle to tip of toe IV (FOL 11.84 mm). (20) Toes long, thin; toe IV long (FTL 6.84 mm) more than one third of distance from base of tarsus to tip of toe IV (TFOL 15.5 mm). (21) Relative length of toes, shortest to longest: I <II <V <III <IV. (22) Tips of toes rounded, not enlarged. (23) Webbing small: I 1 – 2 II 1 – 2 1/ 2 III 1 1/2 – 3 IV 3 – 1 V (MTTF 5.44 mm; MTFF 5.51 mm; TFTF 5.25 mm; FFTF 5.51 mm). (24) Dermal fringe along toe V absent. (25) Subarticular tubercles prominent, oval, simple, all present. (26) Inner metatarsal tubercle short, prominent; its length (IMT 0.78 mm) 2.72 times in length of toe I (ITL 2.12 mm). (27) Inner tarsal ridge present, flat. (28) Outer metatarsal tubercle present, small, rounded; supernumerary tubercles absent; tarsal tubercle absent.

(E) Skin. (29) Dorsal and lateral parts of head and body: snout, between eyes, side of head, anterior part of back and flanks smooth; posterior part of back with indistinct, glandular warts. (30) Latero-dorsal folds absent (light latero-dorsal bands in same position); lateral line system absent; “Fejervaryan” line present; supratympanic fold distinct, from eye to above shoulder. (31) Dorsal parts of limbs: forelimbs and tarsus smooth; thigh shagreened; shank with flat glandular warts. (32) Ventral parts of head, body and limbs: throat with small, dense glandular warts; chest, belly and thigh shagreened. (33) Rictal gland present, two small glands posterior to mouth; other macroglands absent.

(F) Coloration in alcohol. (34) Dorsal and lateral parts of head and body: dorsal parts of head and dorsum brown with light mid-dorsal line and darker indistinct spots, a darker line on each side of posterior back; a dark band from eye to groin; lower flank light grey; loreal region, tympanic region, supratympanic fold and tympanum dark brown; upper lip whitish; rictal gland white. (35) Dorsal parts of limbs: forelimbs light grey with indistinct darker bands; thigh, shank and foot light grey with grey bands; posterior part of thigh with white and blackish longitudinal bands. (36) Ventral parts of head, body and limbs: throat creamy white; margin of throat light grey without spots or bands; chest creamy white; belly and thigh creamy white with greyish spots. Webbing dark grey.

(G) Male secondary sexual characters. (37) Nuptial spines present, one single patch on prepollex and finger I up to subarticular tubercle: numerous, very small, whitish, transparent spines. (38) Vocal sacs present, unique subgular pouch; pair rounded openings in posterior part of mouth floor. (39) No other male secondary characters.

Intrapopulational variation. Morphometric variation is shown in table 1. Coloration is very similar throughout the sample. In some specimens the middorsal line is almost indistinct on the head, whereas in others it is a fine neat line. The colour in life of middorsal line is usually light orange, but can be light yellow or beige.

Coloration in life. Dorsal parts of head and body greyish beige with light orange middorsal line and darker greyish beige longitudinal lines. Upper flank greyish beige, lower part greyish brown; loreal region dark greyish brown with fine blackish canthal stripe; tympanic region and tympanum dark greyish brown with fine blackish stripe along tympanic fold; upper lip golden white. Forearm and dorsal part of thigh light orange with indistinct grey brown bands; dorsal part of shank and foot beige with grey brown bands; hind part of thigh black with yellowish longitudinal stripes. Throat and margin of throat light grey with some golden spots; vocal sacs denser grey; chest and belly whitish with golden shine; “Fejervaryan” line distinct, dark grey; ventral part of thigh greyish. Web greyish brown. Nuptial spines light grey.

Natural history. Chilapata Reserve Forest is a small (41 km ²) moist deciduous forest between Jaldapara Wildlife Sanctuary and Buxa Tiger Reserve in Jalpaiguri District of West Bengal State, India. The forest is flanked by the Torsa and Kaljani rivers flowing down from Bhutan into the ‘ Duars ’ area of Bengal. It is divided into three beats – Chilapata , Bania and Mendabari. Recently 18 species of amphibians have been recorded from this forest.

Minervarya Minervarya Mann-Whitney Minervarya Minervarya Mann-Whitney

chilapata sahyadris U test chilapata sahyadris U test

male N= 8 male N= 10 female N= 2 female N=4

rmfe 272 ± 10.52 297 ± 32.03 U = 8.0 271–275 266 ± 16.73 U = 2.0

251–285 266–359 p = 0.017 * 242–281 p = 0.533 n.s. continued next page.

Minervarya Minervarya Mann-Whitney Minervarya Minervarya Mann-Whitney chilapata sahyadris U test chilapata sahyadris U test male N= 8 male N= 10 female N= 2 female N=4

Specimens have been observed sitting on the ground or under low shrubs near ditches. Calling males were about 10 to 30 cm from the water ( Fig. 2 ). The two adult females were found at a distance of 1-2 m from the ditch, in the grassy band near the road. Some male specimens were sitting on ferns and leaves about 20 cm above ground.

Advertisement call. A part of a call (four notes) of specimen ZSI A 10787 was recorded on 29.07.2007, air temperature was 33°C and water temperature was 31°C. It consists of a succession of long trilled notes. The sequence comprising these four notes last 13.57 s. Note repetition rate is 0.295 note/s. The duration of the notes and the duration of the inter-note intervals between notes increase during the call from 0.858 s to 1.913 s (mean 1.424 s, n = 4) for the note duration and from 2.219 s to 3.032 s (mean 2.551 s, n = 3) for the silent duration. The notes are composed of groups of ill-defined impulsions resulting in a trilled note ( Fig. 3 A). The number of groups of impulsions in each note also increases during the call from 11 to 27 (mean 19.5, n = 4). On the contrary, these groups of impulsions are of constant duration within each note and between notes (about 70.0 ms with a range from 65.0 ms to 75.0 ms). Each group of impulsions consists of a big part which begins abruptly immediately followed by a small part, both parts being composed of several ill-defined and totally irregular impulsions ( Fig. 3 B). The dominant frequency, which is also the fundamental, lies between 2810 and 3870 Hz with a peak at about 3500 Hz. Two harmonic bands are visible, the first one at about 7000 Hz and the second one at about 10500 Hz. The second harmonic band appears to be more emphasized than the first one.

Etymology. Scientific name is derived from “ Chilapata ”, the name of the onymotope, as a noun in apposition, invariable.

Comparison with Minervarya sahyadris . There is a series of morphometrical and morphological differences between the new species and Minervarya sahyadris . Comparison of males with Mann-Whitney U test shows 16 statistically significant differences in 25 measurements ( Table 1 ). M. chilapata is significantly larger than M. sahyadris , but it has smaller head and smaller tympanum size. M. chilapata has shorter forelimb length, but longer tibia length, as well as longer finger and toe length. The webbing of this species is significantly larger than the webbing of M. sahyadris . Principal component analysis separates specimens of both species ( Fig. 4 , Table 2). Six principal component factors show loadings higher than 1 and explain 89.2 % of the overall variance. Principal components obtained were tested for their discriminant potential by ANOVA analysis and only principal component factor 1 shows significant discrimination in relation to taxonomic group. This component describes 40.9 % of overall variation. Head width (HW, IBE), tympanum diameter ( TYD) and incurvation of webbing (TFTF, FFTF) show high positive loading whereas size (SVL), tympanums eye distance (TYE), length of inner toe (ITL) and extension of webbing (MTTF, TFTF) show high negative loadings for factor 1 and thus participate on discrimination of the two species. Vomerine teeth are absent in M. chilapata , but present in M. sahyadris . On the opposite, pineal ocellus is present in M. chilipata , but absent in M. sahyadris . The snout is more pointed in M. chilapata then in M. sahyadris . The tympanum is smaller in M. chilapata than in M. sahyadris . Differences exist in relative length of fingers: IV is shortest in M. sahyadris , whereas in M. chilapata , finger I is shortest; a pair of palmar tubercles is present in M. sahyadris , but a single tubercle, less distinct, in M. chilapata ; the webbing is much larger in M. chilapata than in M. sahyadris ( Fig. 5 ) leaving only three phalanges free in M. chilapata but four in M. sahyadris . The stripe on the upper lip is white in M. sahyadris and golden white in M. chilapata . The middorsal coloration is much more vivid, described as reddish, reddish brown, etc., in M. sahyadris , but greyish beige in M. chilapata . The middorsal line is creamish, golden yellowish or reddish in M. sahyadris , light orange or light yellow in M. chilapata .

Both species show a single nuptial pad which goes up to half penultimate phalange in M. sahyadris , but only to subarticular tubercle in M. chilapata .

The numerous differences in morphology, morphometrics and coloration give support to recognizing the specimens collected in West Bengal as a new species.

Figures

FIGURE 1. Minervarya chilapata. Holophoront, adult male, ZSI A 10784, SVL 20.3 mm. Dorsal and ventral view.

FIGURE 2. Minervarya chilapata. Left: Specimen in life, 29 July 2007; right: Specimen in natural position in the field, June 2008.

FIGURE 3. Sonagram and oscillogram of the advertisement call of Minervarya chilapata, ZSI A 10787, SVL 19.6 mm. (A). Third note showing its trilled appearance (B). Detail of one group of impulsions from the middle of the third note showing the two parts and the irregular impulsions which compose them.

FIGURE 4. Results of principal components analysis (PCA) of 25 morphometric variables for 16 males of Minervarya, showing scores for individual specimens on PC 1 and PC 2. PC 1 separates Minervarya specimens based largely on the different size, head width, tympanum size, and webbing.

FIGURE 5. Ventral view of hand and foot of (left) Minervarya sahyadris, MNHN 2000.3036, and (right) M. chilapata, ZSI A 10790.

Tables

TABLE 1. Mean values of morphometric data of Minervarya chilapata sp. nov. and Minervrya sahyadris ± standard deviation and range. Non-parametric comparison of Minervarya chilapata sp. nov. with Minervarya sahyadris based on Mann-Whitney U test. Abbreviation of measurements as given above; N—number; U—Mann-Whitney U; pprobability. Significance level: *** — p ≤ 0.001; ** — 0.001 <p ≤ 0.01; * — 0.01 <p ≤ 0.1; n. s. — not significant.

svl	20.0 ± 6.95 18.6–20.9	18.4 ± 6.01 17.2–19.2	U = 4.0 p = 0.000 ***	23.8–25.1	22.1 ± 9.16 20.6–23.0	U = 0.0 p = 0.095 *
rhw	306 ± 11.52 290–325	342 ± 15.78 317–369	U = 5.0 p = 0.000 ***	277–295	326 ± 6.09 316–331	U = 0.0 p = 0.095 *
rhl	375 ± 15.36 362–411	392 ± 22.82 365–448	U = 30.0 p = 0.019 *	357–406	366 ± 16.62 345–383	U = 3.0 p = 0.571 n.s.
rmn	364 ± 14.93 330–384	366 ± 33.13 331–428	U = 23.0 p = 0.448 n.s.	354–362	328 ± 24.54 302–352	U = 0.0 p = 0.133 n.s.