Zhangixalus faritsalhadii, Gonggoli & & & & Hamidy & Amir, 2024

Zhangixalus faritsalhadii , new species

( Figs. 4, 5)

Rhacophorus sp. : Alhadi et al. (2021)

Holotype. MZB Amph 32885, an adult male collected from Mt. Slamet , Kalipagu , Ketenger Village , Baturaden District, Banyumas Regency, Central Java Province, Indonesia (7°19′05.33″S, 109°12′17.46″E; elevation 773 m a.s.l) collected by Fajar Kaprawi, Eki Abdul Kholik, and Tarwo on 4 July 2022. GoogleMaps

Paratypes. A total of five specimens: one adult male ( MZB Amph 32886) and three adult females ( MZB Amph 32887–89) collected by the same collectors and from the same locality as the holotype GoogleMaps ; and one male ( MZB Amph 32890) collected by Farits Alhadi, Fajar Kaprawi, Jarian Permana, and Karso on 10 February 2020 from the same locality as the holotype GoogleMaps .

Etymology. The specific epithet “ faritsalhadii ” is an eponym, dedicated to the deceased Farits Alhadi, a herpetologist in Indonesia who collected the first known specimen of this species that is now part of the type series and the first to discover that it could possibly be a new undescribed species on Java.

Suggested English common name. Farits Alhadi’s tree frog.

Suggested Indonesian common name. Katak-pohon Farits Alhadi.

Diagnosis. Based on the molecular analyses, the new species is nested within the clade of the genus Zhangixalus .

Zhangixalus faritsalhadii , new species, can be differentiated from its congeners using the following combination of morphological characters: (1) relatively medium-sized body (SVL 37.6–40.7 mm in males; SVL 50.7–54.5 mm in females); (2) yellowish-green dorsum colouration with numerous dark spot and irregular blotches cream; (3) surfaces of dorsum smooth, covered with small and low spicules; (4) snout in lateral view slope with blunt edge; (5) fringes of skin along limbs and tarsal projection; (6) extensive webbing of toes; (7) finger webbing in males between first to second fingers, and that between second to third fingers reduced, only reaching the distal subarticular tubercle, whereas that in females much more extensive, reaching the base of the disc; (8) webbing between third to fifth toes red; (9) well-developed bilobed supracloacal dermal ridge and tarsal dermal ridge; (10) presence of vomerine teeth; (11) and absence of vocal sac opening.

Description of holotype. MZB Amph 32885 ( Figs. 4A, 5A–F), an adult male SVL 40.7 mm; head longer (HL 14.2 mm, 34.8 % SVL) than wider (HW 13.8 mm, 33.9 % SVL); snout longer (SL 6.5 mm, 15.9 % SVL) than eye distance (ED 4.4 mm, 10.7 % SVL), laterally sloped with blunt edge, and projecting over lower jaw; canthus rostralis distinct; lore oblique, concave; nostril slightly protuberant, without flap of skin, closer to the tip of the snout (SNL 3.1 mm, 7.6 % SVL) than to the eye (NEL 3.2 mm, 7.8 % SVL); internarial distance (IND 4.4 mm, 10.7 % SVL) smaller than interorbital distance (IOD 5.3 mm, 12.9 % SVL); interorbital distance wider than the eyelid (UEW 3.1 mm, 7.7 % SVL); pineal spot absent; pupil of eye horizontal; tympanum distinct, circular, diameter (TD 3.8 mm, 9.4 % SVL) approximately half eye length; choanae circular; vomerine teeth in straight transverse in two series between the choanae and on a level with their anterior borders, not touching the choanae and separated from each other by about two individual ridges; and vocal sac opening absent.

Forelimb slender; relative finger length I <II <IV <III, second finger (Fin2L 4.2 mm, 10.2 % SVL) longer than the first finger (Fin1L 3.4 mm, 8.4 % SVL); tips of fingers expanded into large discs (3FDW 2.3 mm, 5.7 % SVL) with circummarginal and transverse ventral grooves; fingers incomplete webbing, webbing between first and second fingers reduced, it only reaches distal subarticular tubercle on both fingers, webbing formula I 2–2 II 1–2 III 1–1 IV; nuptial excrescences on first finger, from the base of the first finger to the level of the subarticular tubercle; supernumerary tubercles present, but indistinct; prepollex absent; inner palmar tubercle oval (IPTL 2.6 mm, 6.3 % SVL), middle palmar tubercle indistinct, and outer palmar tubercle oval.

Hindlimb slender; relative length of toes I <II <III <V <IV, tibiotarsal articulation of adpressed limb reaching eye; thigh (FML 18.1 mm, 44.5 % SVL) shorter than tibia (TL 19.1 mm, 46.8 % SVL); foot (FL 16.3 mm, 40.1 % SVL) shorter than tibia; tips of toes expanded into a round disc with circummarginal grooves (4TDW 1.8 mm, 4.5 % SVL), smaller than disc of fingers; toe webbing more extensive, toe webbing formula I 1–1 II 1–1 III 1–1 IV 1–1 V; subarticular tubercles well-developed, rounded; supernumerary tubercles indistinct; inner metatarsal tubercles (IMTL 1.6 mm, 4.0 % SVL) oval and low, length more than half length of first toe (Toe1L 2.7 mm, 6.7 % SVL); outer metatarsal tubercles absent.

Dorsum smooth, covered with small and low spicules, also occurs on eyelid and densely in head; abdomen, chest, throat, thigh, cloaca, and flank prominently granular; flanks wrinkled; an oblique thickened skin forms a low supratympanic fold, from the eye and indistinctly ending above arm insertion, slightly touching the tympanic annulus; dorsolateral fold absent; fringe of skin present along the edge of forearm and the outer edge of fifth to tibiotarsal articulation; dermal ridge at tibiotarsal curved, and supracloaca bilobed.

Colour. In life, dorsum yellowish-green with numerous dark spots and irregular cream blotches, dark spots prominent in eyelid, head, and nostril regions; lower lips cream; from the anterior eye to above the nostril, extending to the tip of the snout with a cream line; limbs without crossbars; abdomen, thighs, ventral of tarsus, tibia, lower arms, and upper arms translucent; throat, flanks, elbows, and knees covered with white spot covering the granular; eyes with black periphery, white sclera, dark pupils, and thin pale yellowish network of iris; webbing between third to fifth toes red, yellowish-green on remaining toes; tips of fingers and toes bluishgreen; inguinal region, ventral elbows and knees bluish. In preservative, dorsum green fading to cream and cream blotches become faded, but dark spots remain unchanged; red webbing on toes fading to light red and eyelids turn black.

Variations. The morphometric variations are listed in Table 2. Males had larger RHL, RHW, RSNL, RNEL, RED, RTD, RIND, RUEW, RIPTL, and RIMTL than females, while females had larger SVL, RIOD, RBL, RLAL, Rfin1L,

Rfin2L, Rfin3L, Rfin4L, RFin1DW, RToe3DW, RFML, RTL, RTSL, RFL, RToe1L, RToe2L, RToe3L, RToe4L, RToe5L, RToe1WD, RToe3DW, and RToe4DW than males. A male paratype (MZB Amph 32890) had a smaller body than others. All types of females had a smoother dorsum with no spicules compared to males. In females, webbing on first to second and second to third fingers was more extensive than that for males. Finger webbing formula for females: I 2–1 II 1–1 III 1–1 IV ( Fig. 5K). The tibiotarsal articulation varies among females, but does not exceed the nose and eyes; that for MZB Amph 32887 reaches the nose, that for MZB Amph 32888 reaches between the nose and eyes, and that for MZB Amph 32889 reaches the eyes.

Comparisons. Based on the phylogenetic tree and geographical proximity that separated Sundaland species (Z.

faritsalhadii , new species, Z. prominanus , Z. achantharrhena , and Z. dulitensis ) from Asian mainland species, we only compared Z. faritsalhadii , new species, with the other three Sundaland species. Morphologically, Z. faritsalhadii , new species, is more similar to Z. prominanus , but can be distinguished from the latter with its smaller body (SVL 37.6–40.7 mm vs. 44.4–58.5 mm in males; SVL 50.7–54.5 mm vs. 60.5–70.5 mm in females); dorsum with low spicules which are not prominent in males (vs. appears prominently and elevated; Figs. 6I, J); males snout slope with blunt edge in lateral view (vs. slope with pointed edge; Figs. 6A, B); supracloaca dermal ridge broader and shorter (vs. longer and narrower; Figs. 6M, N); less distribution of melanophores at kness (vs. dense; Figs. 6Q, R); males with reduced webbing on second to third fingers (vs. extensive web finger; Figs. 6U, V).

Zhangixalus faritsalhadii , new species, differs from Z. achantharrhena by having a larger body size (SVL 37.6–40.7 mm vs. 33.5–37.9 mm in males; SVL 50.7–54.5 mm vs. 39.6–44.6 mm in females; see Table 3); more developed webbing on fingers (vs. reduced; Figs. 6U, W); vocal sac opening absent (vs. present); dorsum with small spicules (vs. relatively large; Figs. 6I, K); less distributed melanophores on knees (vs. dense; Figs. 6Q, S); dark spots on dorsum scattered (vs. relatively dense).

Zhangixalus faritsalhadii , new species, differs from Z. dulitensis by having a larger body size (SVL 37.6–40.7 mm vs. 33.6–38.7 mm in males; 50.7–54.5 mm vs. 46.0– 46.9 mm in females; see Table 3); web colouration between third to fifth toes red (vs. only between fourth to fifth toes); vocal sac opening absent (vs. present); shorter supracloaca dermal ridge (vs. longer; Figs. 6M, P); males snout slope with blunt edge in lateral view (vs. slope with sharply pointed edge; Figs. 6A, D); well-developed fringe of skin along the edge of the forearm and the outer edge of fifth to tibiotarsal articulation (vs. less developed).

Range and natural history. The type series of Zhangixalus faritsalhadii , new species, is so far known only from the highlands of Mount Slamet. The type series was found in Rasamala ( Altingia excelsa ) forest near swamps, approximately 10 m from the main river ( Fig. 7). A male paratype (MZB Amph 32890) was collected while it was calling from a palm tree, approximately 15 m above ground, during rainy season in February 2020. During the transition season from the dry to the rainy season in July 2022, two pairs of amplectants of the type series were found on a rattan plant (MZB Amph 32886 and MZB Amph 32889; Fig. 4D) and on tree leaves (MZB Amph 32885 and MZB Amph 32888), while one female (MZB Amph 32889) not far from the same locality was also found. The habitat was surrounded by small puddles formed from water running off the slope. This new species may be in other lowland areas of Mount Slamet. A record dated 18 February 2020 appeared in a citizen science database at the exact location ( Khafizh, 2020). Tadpole and acoustic information are unknown. The following frog species are sympatric with the new species: Polypedates leucomystax ( Gravenhorst, 1829) ; Philautus aurifasciatus ( Schlegel, 1837) ; Limnonectes microdiscus ( Boettger, 1892) ; Rhacophorus reinwardtii ; Leptobrachium hasseltii Tschudi, 1838 ; and Microhyla achatina Tschudi, 1838 .