Chirixalus pantaiselatan, Munir & Hamidy & Kusrini & Kennedi & Ridha & Qayyim & Rafsanzani & Nishikawa, 2021

Munir, Misbahul, Hamidy, Amir, Kusrini, Mirza Dikari, Kennedi, Umar Fhadli, Ridha, Mohammad Ali, Qayyim, Dzikri Ibnul, Rafsanzani, Rizky & Nishikawa, Kanto, 2021, A new species of Chirixalus Boulenger, 1893 (Anura: Rhacophoridae) from the lowland forests of Java, Raffles Bulletin of Zoology 69, pp. 219-234 : 222-229

Chirixalus pantaiselatan , new species

( Figs. 3 , 4 , 5A, B )

Holotype. MZB. Amph 30547 ( Figs. 3 , 4 , 5A ; GenBank accession no. MT 155987 ), an adult male collected on 24 April 2017 from Leuweung Sancang Nature Reserve, Sancang , Cibalong District , Garut Regency , Jawa Barat Province (7°43.73′S, 107°54.08′E; 32 m a.s.l.) by Umar Fhadli Kennedi , Mohammad Ali Ridha , Dzikri Ibnul Qayyim , and Rizky Rafsanzani.

Paratype. Four adult males, MZB. Amph 30548 ( Fig. 5B , GenBank accession no. MT 155986 ); MZB. Amph 30549 ;

MZB. Amph 30550; MZB. Amph 30551 (GenBank accession no. MT 155988 ) from the same locality as the holotype and bearing the same collection data .

Diagnosis. The new species was assigned to the genus Chirixalus based on the following external characters: horizontal pupil, tongue free and deeply notched, distinct tympanum, opposed fingers, toes webbed, tips of fingers and toes dilated into disks, outer metatarsal separated by web, terminal phalanges obtuse ( Boulenger, 1893). The new species can be distinguished from its congeners by the combination of the following characters: snout truncate; SVL 25.3–28.9 mm in males; uniform lateral body colouration, without a light dorsolateral stripe from canthus rostralis through upper orbital to the body or a light lateral stripe from under orbital to mid-body; brown dorsal colouration, with an indistinct transverse dark brown patch on intercanthal and upper eyelid to interorbital area continued by an indistinct irregular hexagon-like shape covering the parietoscapular region, and a diamond-like shape on suprascapular region to mid-body; distinct dark brown tympanum; third finger disk diameter about half that of tympanum and unique advertisement call consisting of short (2–9 notes), medium (11–17 notes), and long calls (22–46 notes). Calls are 185.71–1,644.28, 1,420.78–2,708.46, and 3,292.29–7,055.79 ms in duration, respectively, with note durations of 4.14–18.03, 4.82–15.19, and 4.78–24.88 ms, respectively. Dominant frequencies ranging from 2.34–3.94, 2.53–3.75, and 2.72–3.94 kHz for calls of short, medium, and long duration.

Description of holotype. An adult male; SVL 28.9 mm; head relatively flat and wider (HW = 34.6% of SVL) than long (HL = 32.5% of SVL); snout truncate in lateral view, sloping antero-ventrally, projecting beyond lower jaw, shorter (SL = 13.0% of SVL) than eye diameter (ED = 15.5% of SVL); canthus rostralis rounded; loreal region concave vertically; nostril oval, positioned laterally, closer to tip of snout than to eye (NEL = 63.1% of SL); internarial distance (IND = 7.9% of SVL) about more than half of interorbital distance (IOD = 12.1% of SVL); eyes relatively large (ED = 15.5% of SVL), twice as large as tympanum diameter (TD = 7.2% of SVL), nearly half of head length (ED = 47.9% of HL), protuberant, pupil horizontally elliptical; subcircular, distinct tympanum, nearly twice as large as eye to tympanum distance (ETD = 3.8% of SVL); well-developed rows of vomerine teeth; choana oval shaped; tongue notched posteriorly; single median vocal sac present, vocal slit near commissure of jaws on both sides right and left.

Forelimbs moderate in length, relatively robust, lower arm length nearly half of the snout-vent length (LAL = 43.9% of SVL); a small, rounded inner palmar tubercle (IPTL = 4.1% of SVL), about one-third of third finger length (Fin3L = 13.8% of SVL), outer one absent; indistinct subarticular tubercle between the penultimate and adjoining proximal phalange on third and fourth fingers; finger length formula I <II <IV <III; inner two fingers widely separated from outer two fingers (opposable); no webbing between first and second finger or second and inner third finger, webbing on outer third finger reaching second subarticular and reaching first subarticular on inner fourth finger (III = 1–2 IV); fingers without fringe, tips with a rounded disk, expanded with a circum marginal and indistinct transverse ventral groove; third finger disk diameter about half of the tympanum diameter (Fin3DW = 61.9 % of TD).

Hindlimbs relatively long, slender, tibiotarsal articulation extends to the posterior of nostril when fully stretched leg adpressed to body; thigh (THL = 52.9% of SVL) slightly longer than tibia (TL = 51.9% of SVL), approximately one and one-third of foot (FL = 38.4% of SVL; THL = 137.8% of FL); a well-developed, small, oval inner metatarsal (IMTL = 4.1% of SVL), about one-fifth of fourth toe length (Toe4L = 20.7% of SVL), outer one absent; toe length formula I <II <III <V <IV; webbing formula (I 1– 1 / 2 II 0– 11 / 2 III 0–1 IV 1 / 2 –0 V); toes without fringe, tips with a rounded disk, bearing expanded disks with circum marginal and transverse ventral groove; fourth toe disk (Toe4DW = 3.4% of SVL) much narrower than third finger disk (Fin3DW = 4.5% of SVL).

Dorsal skin surface smooth, scattered with minute tubercles; a distinct supratympanic fold, continuous as a glandular fold to shoulder; skin fold on the corner of jaws, forming a short fold to anterior base of upper arm; lateral forearm, tarsus and foot with minute tubercles; ventral skin surface generally smooth, throat surface composed of small granules, while the abdomen composed of larger granules than those on throat, ventral surface of hand and foot smooth.

Holotype colouration. Body colour changes in living specimens. Specimens captured at night have dark brown colouration on the dorsum and pinkish colouration on the ventral surfaces of limbs and abdomen; dorsum colours change to light yellow or light brown in the morning ( Fig. 5A, B ); pupil dark, iris dark brown to gold; fine dark brown spots on the entire dorsal surface of the body, forelimbs, and hindlimbs; indistinct transverse dark brown patch on interchantal and upper eyelid to interorbital area continued by an indistinct irregular hexagon-like shape covering the parietoscapular region, and a diamond-like shape on suprascapular region to mid-body and irregular blotches near the inguinal region ( Fig. 3A ); presence of a dark transverse band on the forearm, three bands on thigh and three on tarsus; dark brown line along the canthus rostralis; light silver-coloured fold from jaw articulation to anterior of upper arm; uniform dark brown tympanum; clear pinkish ventral surfaces, throat with fine dark spots and darker along the edge of lower jaw, ventral surfaces of forelimbs and hindlimbs with fine dark spots. This colour pattern remains in preserved specimens, with the dorsal surfaces fading to beige and the ventral surfaces fading to dull white.

Variation. Individuals of the type series are morphologically relatively similar, although paratypes have smaller body sizes than the holotype (summary of morphometric variation shown in Table 2). Individuals are slightly variable in colouration, with the rather indistinct dark transverse bands on limbs and irregular dark mark on back in paratypes; all paratypes in life had a yellowish to light brown dorsum; preserved specimens are lighter brown than the holotype.

Advertisement call of the holotype. The description of the advertisement call was made based on the male holotype MZB. Amph 30547. The advertisement call of Chirixalus pantaiselatan , new species, was ascending, consisting of multiple notes, and a single note contained three to five visible harmonics ( Fig. 6 ). Based on the number of notes in one call, we divided the calls of Chirixalus pantaiselatan , new species, into three categories: short (1–10 notes), medium (11–20 notes), and long calls (>20 notes). Advertisement calls differ in call duration and the number of notes in a single call, but their dominant frequencies overlap. Short calls contain 2–9 notes (1 male, n = 34 calls), with a call duration of 185.71–1,644.28 ms (mean ± SD: 703.2 ± 402.75 ms), inter-call interval of 734.7–6,628.5 ms (3,374.41 ± 1,781.6 ms), call period of 1,273.77–7,570.53 ms (4,079.5 ± 1,953.43 ms), note duration of 4.14–18.03 ms (11.0 ± 3.29 ms), inter-note interval of 77.33–394.33 ms (182.5 ± 47.53 ms), note period of 91.99–404.92 ms (192.9 ± 48.37 ms), and dominant frequency of 2.34–3.94 kHz (3.2 ± 0.41 kHz). Medium calls contain 11–17 notes (1 male, n = 4 calls), with a call duration of 1,420.78–2,708.46 ms (1,873.2 ± 570.53 ms), inter-call interval of 1,056.87–1,404.46 ms (1,230.7 ± 245.79 ms), call period of 3,065.46–3,765.33 ms (3,415.4 ± 494.88 ms), note duration of 4.82–15.19 ms (8.4 ± 2.93 ms), inter-note interval of 49.14–313.62 ms (140.9 ± 47.87 ms), note period of 55.79–319.04 ms (149.1 ± 47.98 ms), and dominant frequency of 2.53–3.75 kHz (3.1 ± 0.33 kHz). Long calls contain 22–46 notes (1 male, n = 4 calls), with a call duration of 3,292.29–7,055.79 ms (4,431.2 ± 1,759.7 ms), note duration of 4.78–24.88 ms (11.7 ± 3.55 ms), internote interval of 47.91–247.72 ms (145.4 ± 40.31 ms), note period of 56.1–259.44 ms (157.1 ± 41.15 ms), and dominant frequency of 2.72–3.94 kHz (3.5 ± 0.27 kHz).

Etymology. The specific name is an Indonesian adjective incorporating the words “Pantai,” meaning “coast,” and “Selatan,” meaning “south.” This name refers to the locality of this species in southern Java.

Indonesian Name. Katak-pucat pantaiselatan

Comparisons. The new species Chirixalus pantaiselatan is distinguished from other closely related species Chirixalus trilaksonoi , Chirixalus doriae , Chirixalus dudhwaensis , and Chirixalus simus by the presence of indistinct transversal dark brown patterns on the interchantal and interorbital areas and an indistinct dark mark on the parietoscapular region to mid-body (vs. distinct dark stripes in Chirixalus trilaksonoi , Chirixalus doriae , Chirixalus dudhwaensis , and indistinct dark stripes with some scattered black spots on Chirixalus simus ; see Table 3 for external morphological differences in Chirixalus species ). Chirixalus pantaiselatan , new species, differs morphologically from its sister taxon Chirixalus trilaksonoi by having truncated snout (vs. obtusely pointed); presence of vomerine teeth (vs. absent); a relatively longer head in males, HL = 8.4–9.4 mm (vs. 7.5–8.9 mm); a wider head in males, HW = 8.4–10.0 mm (vs. 7.1–8.8 mm); a relatively longer snout in males, SL = 3.6–4.1 mm (vs. 3.1–3.6 mm); a slightly longer nostril-eye distance in males, NEL = 2.1–2.6 mm (vs. 1.9–2.3 mm); a relatively larger eye diameter in males, ED = 4.3–4.8 mm (vs. 3.1–3.7 mm); a relatively larger eye-tympanum distance in males, ETD = 1.1–1.4 mm (vs. 0.4–0.6 mm); a larger tympanum diameter in males, TD = 2.0– 2.4 mm (vs. 1.4–1.6 mm); a slightly larger internarial distance in males, IND = 2.3–2.4 mm (vs. 1.8–2.2 mm); having a larger interorbital distance in males, IOD = 3.4–4.1 mm (vs. 2.7–3.1 mm); slightly longer lower arm length in males, LAL = 11.4–12.7 mm (vs. 9.7–11.5 mm); a relatively longer hindlimb in males, THL = 12.6–15.3 mm (vs. 10.8–12.8 mm), TL = 13.2–15.2 mm (vs. 12.6–13.9 mm), FL = 9.8–11.1 mm (vs. 8.7–10.1 mm); slightly longer fourth toe in males, Toe4L = 5.3–6.0 mm (vs. 4.4–5.4 mm); wide, distinct transversal bands on limbs (vs. narrow and indistinct); more developed toe webbing, webbing formula = I 1– 1 / 2 II 0– 11 / 2 III 0–1 IV 1 / 2 –0 V (vs. I 1– 11 / 2 II 1 / 2 – 11 / 2 III 0–1 IV 0–0 V); tibiotarsal articulation reaching posterior of the nostril (vs. tip of the snout). The advertisement call characteristics of these two species vary in the number of notes and call duration; Chirixalus pantaiselatan , new species, have short (2–9 notes), medium (11–17 notes), and long calls (22–46 notes) (vs. 2–10 notes: Riyanto & Kurniati, 2014); a more variable call duration, 185.71–1,644.28, 1,420.78–2,708.46, and 3,292.29–7,055.79 ms, in short, medium, and long calls, respectively (vs. 44–370 ms: Kurniati, pers. comm.; incorrectly described in Riyanto & Kurniati, 2014), and lower dominant frequency, ranging from 2.3–3.9 kHz (vs. 3.7–4.8 kHz: Riyanto & Kurniati, 2014).

Chirixalus pantaiselatan , new species, differs from Chirixalus doriae by having vomerine teeth (vs. absent: Boulenger, 1893; Taylor, 1962); presence of a white patch on side of upper jaw (vs. absent: Taylor, 1962; Grismer et al., 2007a); absence of dark postorbital stripe (vs. presence: Grismer et al., 2007a); distinct glandular fold between eye and shoulder (vs. faint: Grismer et al., 2007a); having tympanum diameter about two times that of Fin3DW (vs. equal to that of Fin3DW: Boulenger, 1893; Taylor, 1962; Grismer et al., 2007a); presence of an external vocal sac (vs. absence: Grismer et al., 2007a); third and fourth fingers one-fourth webbed (vs. webbed only at base: Taylor, 1962; Grismer et al., 2007a); tibiotarsal articulation reaching posterior of nostril (vs. reaching eye: Boulenger, 1893; Taylor, 1962); distinct transverse bands on forelimbs and hindlimbs (vs. indistinct to distinct spots: Boulenger, 1893; Taylor, 1962; Aowphol et al., 2013); and more developed webbing on outer margin of third toe (vs. less developed: Taylor, 1962: fig. 88, p. 538). Chirixalus pantaiselatan , new species, is distinguished from Chirixalus dudhwaensis by the absence of a dark postorbital stripe (vs. presence: Ray, 1992; Grismer et al., 2007a); distinct transverse bands on the forelimbs and hindlimbs (vs. absence of markings: Ray, 1992; Das et al., 2012: fig. 4, p. 2557); third and fourth fingers onefourth webbed (vs. less webbed: Ray, 1992); smooth dorsal skin (vs. skin with small tubercles; Ray, 1992); a distinct glandular fold between eyes and shoulder (vs. faint: Ray, 1992; Grismer et al., 2007a). Chirixalus pantaiselatan , new species, is distinguished from Chirixalus simus by having a larger body size, adult male SVL = 25.3–28.9 mm (vs. 22 mm: Annandale, 1915; 20.0–24.0 mm: Deuti, 2013); a distinct canthus rostralis (vs. barely distinguishable: Annandale, 1915); presence of white patch on side of upper jaw (vs. absence; Annandale, 1915; Grismer et al., 2007a); smooth dorsal skin (vs. skin with small tubercles: Annandale, 1915 or smooth: Deuti, 2013); third and fourth fingers onefourth webbed (vs. rudimentary webbing: Annandale, 1915; Deuti, 2013); distinct transverse bands on the forelimbs and hindlimbs (vs. absence of markings: Annandale, 1915); and tibiotarsal articulation reaching posterior of the nostril (vs. tip of snout: Annandale, 1915).

Chirixalus pantaiselatan , new species, is similar to Chirixalus nongkhorensis in dorsal colour pattern, but has a slightly smaller body size, adult male SVL 25.3–28.9 mm (vs. 28 mm: Cochran, 1927; 29–32 mm: Taylor, 1962; 25.6–31.1 mm: Aowphol et al., 2013); truncated snout (vs. pointed: Cochran, 1927; Grismer et al., 2007a); larger eye diameter, ED/SVL = 16.8 ± 1.09, 15.7–18.4% of SVL (vs. 12.2 ± 0.8, 10.6–14.3% of SVL: Aowphol et al., 2013); smaller interorbital distance, IND/SVL 13.6 ± 1.38, 12.1–15.8% of SVL (vs. 19.7 ± 1.4, 11.3–22.1% of SVL: Aowphol et al., 2013); absence of dark postorbital stripe (vs. presence: Grismer et al., 2007a); throat with dark blotches along the ventral edges of the lower jaw (vs. immaculate white: Cochran, 1927; Taylor, 1962); fingers not fringed (vs. fringes along fingers to disks: Cochran, 1927); third finger disk diameter nearly half that of the tympanum (vs. same size as tympanum; Cochran, 1927; Grismer et al., 2007a); outer edge of third finger webbed at base (vs. two-thirds webbed: Cochran, 1927; Taylor, 1962; or one-fourth to one-half webbed: Grismer et al., 2007b); inner edge of the third toes webbed at base (vs. two-thirds webbed; Cochran, 1927); tibiotarsal articulation reaches posterior of nostril (vs. tip of snout; Cochran, 1927). Chirixalus pantaiselatan , new species, also differs from Chirixalus nongkhorensis acoustically, with its advertisement call more variable in duration; means ± SD are 703.2 ± 402.75, 1,873.2 ± 570.53, and 4,431.2 ± 1,759.7 ms for short, medium, and long calls, respectively (vs. 497.8 ± 239.3 ms: Aowphol et al., 2013) and have more notes per call, at 2–9, 11–17, and 22–46 notes per short, medium, and long call, respectively (vs. 2–4 notes: Aowphol et al., 2013) and a slightly lower dominant frequency, ranging from 2.3–3.9 kHz (vs. 3.6–4.3 kHz: Aowphol et al., 2013).

Natural history. During a clear night between 2000–2100 hours, the frogs were found perched on a shrub, approximately 50 cm above the ground near a small pond in an old secondary forest. The egg, larval, and ecological characteristics of this new species are unknown. The following amphibian species were found sympatrically with the new species: Chalcorana chalconota Schlegel , Fejervarya limnocharis Gravenhorst , Ingerophrynus biporcatus Gravenhorst , Kalophrynus pleurostigma Tschudi , Kaloula baleata Müller , Microhyla achatina Tschudi , Occidozyga lima Gravenhorst , Polypedates leucomystax Gravenhorst , and Polypedates macrotis Boulenger. The Polypedates macrotis reported here is the first record of the species occurring in Java (referred specimens MZB. Amph 30420 and MZB. Amph 30421).

Distribution. The new species is known only from the type locality, which is a 21.6 km 2 degraded forest in the Leuweung Sancang Nature Reserve, Garut Regency, Jawa Barat.

Figures

Fig. 3. Dorsal (A) and ventral (B) views of the holotype Chirixalus pantaiselatan, new species, MZB. Amph 30547. Scale = 5 mm.

Fig. 4. Ventral of right foot (A) and right hand (B) views of the holotype Chirixalus pantaiselatan, new species, MZB. Amph MZB. Amph 30547. Scales = 5 mm.

Fig. 5. Chirixalus pantaiselatan, new species, MZB. Amph 30547 in night-time (A) and MZB. Amph 30548 in the daytime (B), uncollected Chiromantis trilaksonoi (C), and Feihyla vittiger, MZB. Amph 27238 (D). C & D photographed by Farits Alhadi.

Fig. 6. Oscillogram and spectrogram of Chirixalus pantaiselatan, new species, MZB. Amph 30547, long call (A), and short call (B). The samples of advertisement calls are available at https://doi.org/10.6084/m9.figshare.14554179