Microhyla orientalis, Matsui, Masafumi, Hamidy, Amir & Eto, Koshiro, 2013

Matsui, Masafumi, Hamidy, Amir & Eto, Koshiro, 2013, Description of a new species of Microhyla from Bali, Indonesia (Amphibia, Anura), Zootaxa 3670 (4), pp. 579-590 : 584-588

Microhyla orientalis sp. nov.

Synonymy: Microhyla achatina: McKay, 2006 , p. 34.

Holotype. MZB.Amp 20404 (formerly KUHE 55073), an adult male from Wongaya Gede, Bali, Indonesia (08o25'03''S, 115o07'28''E, alt. 435 m a.s.l.: Fig. 1 ), collected on 7 August 2012 by K. Eto.

Paratypes. MZB.Amp16259, an adult female from Batukaru, Bali, Indonesia (08o22'24''S, 115o06'24''E, alt. 815 m a.s.l.), collected on 12 July 2010 by A. Hamidy, M.D. Kusrini., and U. Arifin; KUHE 55049, 55074, 55075 (three adult males), KUHE 55050, 55072 (two adult females), and KUHE 55076 (one subadult female) from the type locality, collected from 7 to 8 August 2012.

Referred specimens. KUHE 47215 (five tadpoles), collection data same as the holotype.

Etymology. The specific epithet is from a Latin word orientis denoting eastern, alluding to the fact that the species from Bali represents geographically the easternmost species of Microhyla .

Diagnosis. The new species is assigned to Microhylidae by the possession of median spiracle in larvae, and to Microhyla among members of the family from Southeast Asia by: lack of small spine-like projection of skin at heel and elbow; belly without a brown network; underside of fingers without greatly enlarged tubercles; snout less than twice diameter of eye; inner metatarsal tubercle low, not shovel-like; tympanum hidden by skin (Inger, 1966). A small form of the genus, adult males about 16–17 mm in SVL; snout rounded in profile; first finger short, less than one-fifth of third; tips of three outer fingers weakly dilated, forming weak disks, dorsally with median longitudinal groove; outer palmar tubercle single; tibiotarsal articulation reaching up to center of eye; tips of toes distinctly dilated into disks, dorsally with median longitudinal groove; two or more phalanges on outer side of second toe, more than three phalanges on inner side of third toe, three or more phalanges on outer side of third toe, four or more phalanges on inner and outer sides of fourth toe, and three phalanges on inner side of fifth toe free of web; inner and outer metatarsal tubercles present; eyelid without supraciliary spines; faint vertebral stripe present; a black lateral stripe from behind eye to half length of trunk; tail of larva with a black marking at middle.

Description of holotype (measurements in mm). SVL 16.6; habitus moderate ( Fig. 3–4 ); head triangular, wider (5.5) than long (5.1); snout rounded dorsally and in profile, projecting beyond lower jaw; eye shorter (2.2) than snout (3.2); canthus rostralis rounded; lore sloping, very weakly concave; nostril lateral, below canthus rostralis, closer to tip of snout (1.0) than to eye (1.2); interorbital distance (1.6) subequal to internarial distance (1.6), the latter larger than upper eyelid (1.2); pineal spot absent; tympanum hidden; upper jaw edentate; tongue oval, without papillae; slit-like openings to a median subgular vocal sac.

Forelimb short (9.9); fingers thin, free of web, but with slight skin fringes on both sides of second and third and inner side of fourth; second finger slightly longer (measured from inner side 1.9, outer 1.3) than fourth (inner 1.7), latter much longer than first (outer 0.6); tips of three outer fingers weakly dilated and forming weak disks slightly wider than basal phalanges, dorsally with median longitudinal groove; diameter of first finger (0.2) one-third that of third finger disk (0.6), latter one and half times width of phalange; a single outer palmar tubercle (0.6) larger than inner (0.4); distinct, rounded subarticular tubercles, formula 1, 1, 2, 2; nuptial pad absent ( Fig. 5 ).

Hindlimb moderately long (28.5) about three times length of forelimb; tibia long (9.0), heels overlapping when limbs are held at right angles to body; tibiotarsal articulation of adpressed limb reaching to center of eye; foot (9.4) longer than tibia; tips of toes distinctly dilated into disks, much wider than those of fingers (disk diameter of third toe 0.7), dorsally with median longitudinal groove; third toe longer than fifth; webs between toes poorly developed ( Fig. 5 ) and absent between first and second toes, formula (the number of phallanges free of web): I n.a.–n.a. II 2– 3 + III 3 –4 + IV 4 +– 3 V; subarticular tubercles prominent, rounded, formula 1, 1, 2, 3, 2; inner metatarsal tubercle oval, large, length (0.8) half of first toe (1.6); outer metatarsal tubercle elevated, smaller (0.5) than inner.

Skin smooth above with a few low tubercles scattered; eyelid without supraciliary spines; no supratympanic fold discernible; side of body sparsely scattered with tubercles or low ridges; hindlimb dorsally scattered with few tubercles; ventral side of body and limbs smooth.

Color. Color in life pinkish brown dorsally, with a dark mark medially continued from interorbital bar posteriorly to cloacal opening; interorbital bar, reverse triangle in shape and covering posterior half of upper eyelid; dorsal dark mark forming subtriangle marks on shoulder and behind sacrum, and running laterally to form a widelimbed reverse V-shaped mark in between on middle of back; a narrow, discontinuous vertebral line from tip of snout to above anus; a black lateral stripe extending from above arm to half length of trunk; a paler dark marking connecting interorbital bar and lateral stripe, dorsally bordering the latter; a dark stripe from snout to eye; a cream stripe extending from eye to axilla; except for upper arm, limbs dorsally with narrow dark brown bars; throat and chest darkly pigmented and abdomen cream white; iris dorsally and ventrally golden with black reticulation, darkly pigmented at anterior and posterior corners ( Figs. 3–5 ). In preservative, pattern has not obviously changed, although color has slightly faded.

Variation. Individuals of the type series are generally similar in appearance. Variation in size and body proportions is given in Table 3 . Female paratypes have a larger body size (> 18.3 mm SVL) than the males (<17.4 mm SVL), but tend to have shorter hindlimbs relative to SVL; tibiotarsal articulation of adpressed limbs reaching the posterior border of the eye in females, and the center of the eye in males. Webbing formula was stable for the outer side of the first toe, where web is absent, but slight variations are recognized in other positions, e.g., in a paratype (KUHE 55072), webbing is absent from the first toe to the inner side of the third toe, while another (KUHE 55075) had slight webbing on the inner side of the second toe. Throats of females are less darkly pigmented than those of males.

Tadpoles. A total of five tadpoles from St. 39 (total length= 19.9 mm, head-body length= 7.1 mm) to 40 (23.2 mm, 7.1 mm) from the type locality of M. orientalis and identified as that species by DNA analyses were closely examined. Head and body flattened above, spheroidal below; maximum head-body width at level of eye 63–66% (median=63%) of head-body length; maximum head-body depth 84–96% (median=92%) of maximum head-body width; snout broadly rounded, almost truncate in profile; eyes lateral, visible from below, eyeball diameter 14–16% (median=15%) of head-body length; interorbital space very wide, 322–371% (median=337%) of eyeball diameter; eye-snout distance 25–31% (median=29%) of head-body length. Oral disk dorso-terminal, small; lower lip moderately expanded with width 21–25% (median=22%) of maximum head-body width, with a prominent lateral papilla on each side; labial teeth and jaw sheaths entirely absent, but lower labium scattered with small papillae on lateral margin. Spiracle opening median, without free flap, opening 70–85% (median=81%) of distance from tip of snout to end of body; vent median, in form of long tube directed nearly vertically downward, small opening at edge of ventral fin; thick loops of gut visible ventrally. Tail long and lanceolate, abruptly tapering in posterior half and drawn out into a short filament; tail length 182–251% (median=221%) of head-body length, maximum depth 25– 28% (median=26%) of length; dorsal fin originating at end of head-body, with a straight margin, sub-parallel with much deeper ventral fin in anterior half of tail; ventral fin deeper than dorsal throughout anterior to tail tip; caudal muscle moderately strong, maximum tail width 36–44% (median=39%) of maximum head-body width; muscle depth maximum at origin, 52–68% (median=57%) of maximum tail depth, but steadily narrowed posteriorly, with depth at middle of tail shallower than fin depths. Color in life ( Fig. 6 ) light brown on dorsum and laterally, with a pair of paler interorbital markings and darker mid-dorsal band, and marking at end of flank; venter grey and belly semi-translucent; tail at middle with a black marking dotted with golden.

Range. The new species is so far known only from Wongaya Gede and Batukaru, Bali Island, Indonesia.

Natural history. Microhyla orientalis sp. nov. is sympatric with M. palmipes on Bali around Wongaya Gede (type locality) and Batukaru, while at Ubud, only M. palmipes was found. They are actually syntopic and can be found very close to each other in the localities of sympatry. At Batukaru, calls of M. orientalis were frequently heard in mid July, but at Wongaya Gede, calls were rarely heard in early August, while tadpoles approaching to metamorphosis were observed. In both cases, M. palmipes was actively calling. Thus the new species may have shorter breeding seasons than M. palmipes . Tadpoles were found in paddies with larval M. palmipes .

Call characteristics. Calls were recorded at Batukaru at an air temperature of 26.0°C at 21:00 h on 12 July 2010 by A. Hamidy. Calls (33 notes from two males were analyzed) consisted of a series of notes each emitted at an interval (between the beginnings of two successive notes) of 0.54±0.13 (0.37−0.97) s ( Fig. 7 ). Each note was composed of 4.1±0.7 (3−5) short pulses and lasted for 0.07 ± 0.01 (0.01−0.08) s. Frequency bands spread over the 1.0–5.3 kHz range, and the dominant frequency was 3.4±0.1 (3.2−3.6) kHz. Frequency and intensity modulations were not marked.

Comparisons. Microhyla orientalis sp. nov. can be differentiated from genetically close members of the M. achatina group of Matsui et al. (2011) and sympatric congeners in the following way. The new species differs from M. achatina by having dorsal dark markings covering the posterior half of the upper eyelid, a lateral dark band beginning at the base of the upper arm and vaguely bordered, and four or five dark bars on limbs (vs. dark marking posterior to upper eyelid, lateral band strong and clearly bordered, and two bars on limbs). From M. berdmorei (Blyth) , the new species differs by poorly developed toe webbing (vs. very well developed webbing). The new species differs from M. borneensis by larger body size, male SVL 15.8–17.4 mm, and less developed toe webbing, with fifth toe with more than three phalanges free (vs. 11.0– 13.2 mm and two phalanges free). The new species differs from M. fissipes Boulenger , M. mixtura Liu and Hu , M. okinavensis Stejneger , and M. pulchra (Hallowell) by having finger and toe disks with dorsal median longitudinal grooves (vs. disks and grooves entirely absent or present only on toes). From M. heymonsi Vogt , the new species differs by having two metacarpal tubercles and lacking loreal mask or marking on the vertebral line (vs. having three tubercles, a black band covering side of head, and one or two pairs of black marks on sides of vertebral line). The new species differs from M. malang by a smaller body size, male SVL 15.8–17.4 mm, and less developed toe webbing, with the fifth toe having more than three phalanges free (vs. 19.4–22.2 mm and one phalange free), and from M. mantheyi by a smaller body size, male SVL 15.8–17.4 mm, uniformly brown head, and less developed toe webbing, with the fifth toe with more than three phalanges free (vs. 18.8–29.2 mm, snout cream colored, and one phalange free). Finally, from M. palmipes , the new species differs by lacking a supraciliary tubercle, having much less developed toe webbing, and the presence of dorsal median grooves on digital disks (vs. having a supraciliary tubercle and fairly developed toe webbing, and lacking the grooves).

Figures

FIGURE 1. Map of Bali, Indonesia, showing the known distributions of Microhyla orientalis sp. nov. The filled star and filled circle, respectively, indicate the type localities of Wongaya Gede and Batukaru. Microhyla palmipes was sympatric with M. orientalis at both localities. The open circle indicates Ubud, where only M. palmipes was found.

FIGURE 3. Dorsolateral view of male holotype of Microhyla orientalis sp. nov. (MZB. Amp 20404) from Wongaya Gede, Bali, Indonesia.

FIGURE 4. Dorsal (A) and ventral (B) views of male holotype of Microhyla orientalis sp. nov. (MZB. Amp 20404). Scale bar = 10 mm.

FIGURE 5. Ventral view of left hand (A) and foot (B) of male holotype of Microhyla orientalis sp. nov. (MZB. Amp 20404). Scale bar = 5 mm.

FIGURE 6. Larval Microhyla orientalis sp. nov. from Wongaya Gede, Bali, stage 40 of Shimizu & Ota (2003), total length = 23.2 mm. Dorsal (A), lateral (B), and ventral views (C). Scale bar = 5 mm.

FIGURE 7. Sonagram (A) and wave form (B) showing four successive notes of an advertisement call of Microhyla orientalis sp. nov. from Batukaru, Bali, recorded at an air temperature of 26.0 ° C.

Tables

TABLE 3. Measurements of adult Microhyla orientalis sp. nov. types. SVL (Mean ± 1 SD, in mm) and medians of ratios (R) of other characters to SVL, followed by ranges in parenthesis. See text for character abbreviations.

	Males (N = 5)	Females (N = 2)
SVL	16.7 ± 0.7 (15.8−17.4)	18.8 (18.3−19.2)
RHL	31.4 (30.7−35.4)	30.7 (29.7−31.7)
RHW	33.1 (32.2−36.7)	33.6 (32.8−34.4)
RIND	9.2 (8.8−9.9)	8.1 (7.7−8.5)
RIOD	9.5 (8.8−11.0)	9.0 (8.9−9.1)
RUEW	7.8 (7.0−8.6)	6.7 (6.2−7.3)
REL	13.9 (13.1−14.9)	13.5 (13.0−14.0)
RED	11.4 (10.7−12.9)	9.9 (9.5−10.3)
RLAL	43.0 (39.7−46.0)	41.1 (40.1−42.1)
RFLL	58.9 (54.1−60.1)	53.3 (53.1−53.6)
RIPTL	3.1 (2.5−3.8)	2.5 (2.3−2.6)
ROPTL	3.9 (3.1−4.7)	3.6 (3.4−3.7)
RTL	54.0 (50.6−56.3)	51.5 (50.0−53.0)
RFL	56.6 (50.6−57.7)	52.6 (51.6−53.6)
RHLL	171.5 (159.2−173.0)	163.0 (160.0−166.1)
RIMTL	5.1 (3.4−5.8)	3.8 (3.7−3.8)
R1TOEL	9.3 (7.6−12.7)	8.7 (8.1−9.4)
ROMTL	3.6 (2.4−5.5)	2.5 (2.4−2.5)