Mercurana myristicapalustris

Abraham, Robin Kurian, Pyron, R. Alexander, Zachariah, Arun & Zachariah, Anil, 2013, Two novel genera and one new species of treefrog (Anura: Rhacophoridae) highlight cryptic diversity in the Western Ghats of India, Zootaxa 3640 (2), pp. 177-189 : 183-187

Mercurana myristicapalustris gen. et sp. nov.

( Fig. 4 C)

Holotype: TNHM (H) 12.6.18 /69, an adult male (SVL 35.4 mm) ( Fig. 5 ), collected by Ansil B. R. on 18th May, 2012, from bushes at the periphery of a temple compound, Arippa (8.8392N, 77.0314E, altitude approximately 184m ASL), near Kulathupuzha Reserve Forest, Kollam district, Kerala, India.

Paratypes: TNHM (H) 12.6.18 /70 and TNHM (H) 12.6.18 /74, two adult males collected by Robin K. Abraham on 12th July, 2012 from the type locality. Measurements of all specimens provided in Table 1.

Etymology: The generic epithet is derived from ‘Mercury’ as a tribute to Freddie Mercury, late lead singer of the British rock band Queen, whose vibrant music inspires the authors, in combination with Rana ( Linnaeus, 1758) , a suffix commonly used for many frog taxa. Gender is masculine. The specific epithet, a combination of the words ‘myristica’ for the nutmeg family, and ‘palustris’, which is latin for swampy, emphasizes the Myristica swamp forest habitat of this frog, which is a fragile and threatened habitat type of the Western Ghats.

Diagnosis: The diagnosis is valid for the genus and species. Mercurana myristicapalustris can be distinguished from other rhacophorid genera by the following combination of characters: medium sized frog (average male SVL 36.1, N=3; female SVL 65.1mm, N=1); weakly-developed vomerine teeth present; simple tubular Wolffian duct; eggs non-pigmented; early embryonic development occurs in wet mud after pre-monsoon showers; free living aquatic tadpoles; arboreal adults inhabit low-elevation swamp forests. Mercurana , which could potentially be confused with Beddomixalus , differs from the latter in the following characters: presence of vomerine teeth and lingual papilla (vs. absence); symphysial knob not sharply pointed (vs. sharply pointed); no stripe on the dorsolateral margin (vs. pale distinct stripe on the dorsolateral margin); canthus rostralis indistinct (vs. rounded); toes 3/4th webbed (vs. half/moderately webbed); finger discs large (vs. moderate); subarticular tubercle on finger IV bifid (vs. rounded); oviposited eggs mixed with mud in shallow pit (vs. eggs openly scattered on ground substrates) and; inhabits low-elevation forests (vs. mid- to high- elevation forest).

Description of Holotype: A slender, medium sized frog (average male SVL 35.4mm); dorsal skin texture shagreened; ventral surface including chest, belly and posterior surface of thighs coarsely glandular; throat slightly glandular; lateral profile of snout rounded and protruding; canthus rostralis indistinct, loreal region obtusely concave; pupil oval and horizontal; tympanum rounded and faintly distinct, faint supratympanic fold from back of eye to shoulder; weakly-developed vomerine teeth oblique and anterior to choanae; tongue lanceolate; lingual papilla absent; small vocal sac; fingers free, toes 3/4th webbed (from inner aspect of disc on Toe V reaching up to the distal subarticular tubercle of Toe IV, resuming from penultimate subarticular tubercle of Toe IV to distal subarticular tubercle of Toe III); subarticular tubercles prominent, rounded, except on finger IV, which is strongly bifid; supernumerary tubercles well developed; discs well developed and distinct; Wolffian duct simple, tubular (not illustrated, but similar to that of Beddomixalus ; Fig. 6 ).

Colour in life: Male: Dorsal surface of forearm, hindlimbs and entire body rusty-brown with small black speckles scattered throughout; handful of tiny, sparsely spaced yellow blotches on dorsum; axillary region on the underside of arms white, suffused with yellow splotches; upper-arm from shoulder to elbow and hand yellowish; flank white with diffused yellow on groin; upper lip whitish; ventral surface uniformly off-white; forelimbs and hindlimbs without any crossband pattern; anterior and posterior border and ventral surface of thigh whitish; vent fold absent; iris silvery-brown with a yellowish tinge. In non-breeding condition, the dorsum of the male is pale yellowish-brown, but with the black speckles. Female: pale greenish-yellow dorsum; ventral surface white.

Geographic distribution and habitat: The species Mercurana myristicapalustris was documented only in lowland swampy areas of the western foothills of the Agasthyamalai Hill Range in Kerala (see Fig. 7 ). These areas are dominated by Myristica swamp formations ( Fig. 4 A), a unique biotope of the Western Ghats. The type locality is outside the protected area network, but at the periphery of the Kulathupuzha Reserve Forest. We have also recorded the species in lowland areas of the Shendurney Wildlife Sanctuary in Kollam district (8.8678N, 77.0939E; 188m ASL) and further south in Peppara Wildlife Sanctuary, Thiruvananthapuram district (8.6697N, 77.1197E; 208m ASL).

Breeding behaviour: The frog Mercurana myristicapalustris is an arboreal species whose breeding behaviour is remarkably similar to that of Beddomixalus bijui , in terms of large male aggregations at breeding sites during the pre-monsoons and oviposition on the swamp floor. Vocalizing males ( Fig. 4 C) (audio file of call deposited in the Dryad Repository as Supplementary file 2; http://dx.doi.org/10.5061/dryad.pm166) call from atop perches inside the swamp forest with standing water or intermittent streams, at 2-5m height from the forest floor. As the night progresses, the males make their way slowly towards the forest floor, where competition for space is greater and on one occasion, we witnessed physical combat between males. We were able to make only a brief observation of amplectic behaviour in M. myristicapalustris . A male and female in amplexus were seen descending to the swamp floor, from the base of a shrub. On reaching the ground, the pair moved into the leaf litter where both individuals slowly changed colour, becoming almost inconspicuous on the forest floor. The female was seen digging into the slushy soil and ovipositing into the resulting shallow burrow in the mud, following which she mixed the semiterrestrial eggs with muddy soil. Digging and mixing was aided by employing her well-developed hindlimb webbing. Ensuing oviposition, the pair moved away, after which they could not be relocated. Photographic documentation of breeding behaviour was not possible because of failure of camera equipment at the time. However, clutches of developing eggs washed loosely in the swamp floor along a rivulet, and a single early stage tadpole ( Fig. 4 D), which did not yield an accurate LTRF, were photographed after a few days of pre-monsoon showers. The tadpole was sequenced to determine species identity, and confirmed to be that of Mercurana .

Museum Sex SVL HW HL IUE UEW SL EL FLL HaL TL ShL TaL FoL Vo u c h e r. N o.

Beddomixalus bijui

ZSI/WGRC/V/ Male 40.1 14.1 12.0 4.7 3.6 5.7 5.0 9.0 11.6 20.0 20.0 11.0 17.1 A/842

ZSI/WGRC/V/ Male 42.0 14.4 12.0 4.7 3.9 5.6 5.0 8.9 12.0 20.0 21.4 11.0 17.3 A/843

ZSI/WGRC/V/ Male 40.3 14.3 11.9 4.4 3.8 5.7 5.0 8.9 12.1 20.0 20.1 11.0 17.2 A/844

ZSI/WGRC/V/ Female 60.8 24.4 21.6 7.3 5.3 8.1 6.5 13.8 18.8 32.1 32.3 17.7 28.5 A/849

Mercurana myristicapalustris

Holotype Male 35.4 11.9 9.8 4.1 3.0 5.2 5.1 8.4 8.2 17.8 17.7 9.8 13.0 TNHM (H)

12.6.18 /69

TNHM (H) Male 35.1 12.9 12.0 4.3 2.8 5.0 5.0 8.5 8.0 21.1 18.2 11.7 14.5 12.6.18 /70

TNHM (H) Male 37.8 14.1 15.7 4.8 4.2 5.6 5.5 9.9 10.6 18.7 20.5 12.0 13.4 12.6.18 /74

Mean 36.1 13.0 12.5 4.4 3.4 5.2 5.2 8.9 8.9 19.2 18.8 11.2 13.6 Beddomixalus bijui Tadpole

Gosner Stage 38 TL BL TAL BW BH NSD END TMH TMW SSD IND IOD ED TNHM (H) 12.6.22 /73 29.1 9.9 20.3 5.6 4.1 1.8 1.1 2.7 2.4 7.0 1.7 1.5 1.5

Abbreviations for adult measurements: SVL = snout-vent length; HW = head width, at angle of jaw; HL = head length, from rear of mandible to tip of snout; IUE = inter upper eyelid width, the shortest distance between the upper eyelids; UEW = maximum upper eyelid width; SL = snout length, from tip of snout to anterior orbital border of eye; EL = eye length; FLL = forelimb length, from elbow to base of outer palmar tubercle; HaL = hand length, from base of outer palmar tubercle to tip of third finger; TL = thigh length; ShL = shank length; Tal = tarsal length; FoL = foot length, from base of inner metatarsal tubercle to tip of fourth toe. Abbreviations for tadpole measurements: TL = total length; BL = body length; TAL = tail length; BW = body width; BH = body height; NSD = naris-snout distance; END = eye-naris distance; TMH = tail muscle height at the base of the tail; TMW = tail muscle width; SSD = snout-spiracle distance; IND = internarial distance; IOD = interorbital distance; ED = eye diameter.

Figures

FIGURE 4. Mercurana myristicapalustris gen. et sp. nov. A. General habitat comprising primarily of lowland Myristica swamp forest; B. typical breeding habitat on the muddy banks of small rivulets; C. vocalizing male; D. eggs with enlarged jelly (upon hydration after rains) and tadpole.

FIGURE 5. Holotype of Mercurana myristicapalustris gen. et sp. nov. A. dorsal view; B. ventral view; C. lateral view of head; D. ventral view of foot; E. ventral view of hand.

FIGURE 6. Diagram of a pair of simple tubular Wolffian Ducts and associated organs of a male Beddomixalus bijui. Notations: A = Kidneys, B = Testes, C = Fat Bodies, WD = Wolffian Duct.

FIGURE 7. Map showing distribution of Mercurana myristicapalustris gen. et sp. nov. and Beddomixalus gen. nov. bijui in the southern Western Ghats, India; coloured markers indicate type localities.