Litoria daraiensis, Richards & Donnellan & Oliver, 2023

Richards, Stephen J., Donnellan, Stephen C. & Oliver, Paul M., 2023, Five new species of the pelodryadid genus Litoria Tschudi from the southern versant of Papua New Guinea’s Central Cordillera, with observations on the diversification of reproductive strategies in Melanesian treefrogs, Zootaxa 5263 (2), pp. 151-190 : 154-157

publication ID	https://doi.org/ 10.11646/zootaxa.5263.2.1
publication LSID	lsid:zoobank.org:pub:9EF23FE9-DDD8-46D4-A275-09A35243BF30
DOI	https://doi.org/10.5281/zenodo.7814484
persistent identifier	https://treatment.plazi.org/id/0760AD74-4A52-4980-AA2E-46F4C325BA7B
taxon LSID	lsid:zoobank.org:act:0760AD74-4A52-4980-AA2E-46F4C325BA7B
treatment provided by	Plazi
scientific name	Litoria daraiensis
status	sp. nov.

Treatment

Litoria daraiensis , sp. nov.

Darai Plateau Treefrog

Figs 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3

https://zoobank.org/ urn:lsid:zoobank.org:act:0760AD74-4A52-4980-AA2E-46F4C325BA7B

Holotype. SAMA R71675 ( FN JCUNQ [ SJR]3136), adult female, Darai Plateau , Gulf Province, Papua New Guinea (7.1295°S, 143.6134°E; 435 m a.s.l.) on 23 July 2003 by S. Richards. GoogleMaps

Paratype (n = 1). SAMA R71676 ( FN JCUNQ [ SJR]3181) , adult male, same location and collector details as for holotype except collected on 25 July 2003 .

Diagnosis. Litoria daraiensis sp. nov. is distinguished from all other Litoria by the following unique combination of characters: size small (SVL of one male 23.9 mm, of one female 30.2 mm); dorsum in life brown with green spots; vomerine teeth absent; finger webbing extensive, reaching nearly to distal subarticular tubercle on inside edge of Finger 4; prominent dermal fold along outer edge of foot; advertisement call a harsh chattering sound lasting 0.35– 0.37 s containing 10–11 distinctly pulsed notes produced at 27–29 notes/s with dominant frequency at 3400–3600 Hz; and is genetically diagnosable from L. gracilis sp. nov. at 46 sites in the 787 base pair alignment of mitochondrial ND4 gene and flanking tRNA ( Table 1 View TABLE 1 ).

Description of holotype. An adult female containing large (1.5–1.8 mm diameter), predominantly yellow eggs. Body slender; limbs moderately long (TL/SVL 0.52); head moderately narrow (HW/SVL 0.30), slightly narrower than length (HL/SVL 0.31, HW/HL 0.96). Vomerine teeth absent. Tongue large, narrowly oval, with distinct posterior notch. Snout broadly rounded in dorsal view ( Fig. 1A View FIGURE 1 ), steep, bluntly rounded in lateral view ( Fig. 1B View FIGURE 1 ); canthus rostralis short, strongly curved and broadly rounded; loreal region sloping, slightly concave; lips slightly flared; nostrils much closer to tip of snout than eyes, oriented laterally; internarial distance greater than distance from external naris to eye (EN/IN 0.93); eyes small (EYE/SVL 0.11), but protruding in dorsal and ventral views; pupil horizontal, pigmentation on nictitating membrane restricted to narrow band along dorsal edge; tympanum moderately large (TYM/SVL 0.05), nearly one-half diameter of eye (TYM/EYE = 0.48), ventral 2/3 extremely prominent, dorsal one third obscured by thick, slightly curved supratympanic ridge.

Skin of dorsum and dorsal surfaces of limbs finely shagreened; throat ridged anteriorly, becoming coarsely granular posteriorly; chest and abdomen coarsely granular; ventral surfaces of limbs mostly smooth except proximal 2/3 distance along posteroventral margins of thighs with numerous tubercles; dense cluster of prominent white tubercles below vent forms short transverse ridge then tubercles extend distally about 9.5 mm along posteroventral margins of each thigh, losing white colour and becoming translucent distally. A prominent crenulated white dermal fold, nearly unbroken, along outer edge of foot, extending from heel to distal subarticular tubercle on Toe 5; row of small pale tubercles along outer edge of forearm grades into distinct low crenulated fold along outer edge of hand reaching distal subarticular tubercle on Finger 4.

Fingers moderately short with expanded terminal discs (3FD/SVL 0.05; 3FD/3FP 1.36) with distinct marginal grooves; distal subarticular tubercles strongly bilobed; proximal tubercle unilobed; relative lengths of fingers 3>4>2>1 ( Fig. 1C View FIGURE 1 ). Webbing on inside of Finger 4 reaching half-way between distal subarticular tubercle and disc on left hand, but not reaching distal tubercle on right hand, before extending to disc as fleshy fringe; on outside of Finger 3 reaching to base of distal subarticular tubercle ( Fig. 1C View FIGURE 1 ); on inside of Finger 3 reaching to just above proximal subarticular tubercle and on outside of Finger 2 reaching to base of disc; webbing only a basal fringe between fingers 1 and 2. Hand with low, oval inner and narrow oval outer, metacarpal tubercles. Toes with expanded terminal discs (4TD/4TP 1.18) with terminal grooves, discs on toes smaller than those on fingers (3FD/4TD 1.15), relative lengths of toes 4>5=3>2>1 ( Fig. 1D View FIGURE 1 ). Webbing on inside of Toe 5 reaches nearly to disc, on both sides of Toe 4 to base of distal subarticular tubercle, on outside of Toe 3 to beyond halfway between distal subarticular tubercle and base of disc, on inside of Toe 3 to base of distal tubercle, on outside of Toe 2 nearly to base of disc, on inside of Toe 2 to proximal tubercle and on outside of Toe 1 to distal tubercle. Foot with prominent narrow, elongate inner metatarsal tubercle, outer tubercle barely detectable ( Fig. 1D View FIGURE 1 ).

Colour in life ( Fig. 2A View FIGURE 2 ). Dorsum pale, green-tinged ivory with green spots and flecks across dorsal surfaces including limbs; dark-brown pigmentation aggregated into small patches on limbs and lateral surfaces; a large patch of brown pigmentation laterally behind axillae, and another on head where it forms broad ‘V’ shape mark between eyes. Ventral surfaces white anteriorly with clumps of brown pigment near angle of jaws, yellow posteriorly and on hidden surfaces of limbs. Dermal folds on limbs and tubercles on limbs and around vent white. Iris ivory with brown reticulations, narrow yellow rim surrounding pupil. Hands and feet translucent, with dense brown spotting and small patches of green dorsally.

Colour in preservative. In preservative dorsal surfaces pale milky blue with scattered darker blue and brown flecks, ventral surfaces of legs pale yellow, tubercles on limbs white, ventral surfaces of hands and feet translucent white.

Measurements of holotype (in mm). SVL 30.2; TL 15.8; HL 9.5; HW 9.1; EYE 3.3; TYM 1.6; EN 2.7; IN 2.9; 4TD 1.3; 4TP 1.1; 3FD 1.5; 3FP 1.1; TL/SVL 0.52; HW/HL 0.96; TYM/EYE 0.48; EN/IN 0.93; 3FD/4TD 1.15.

Variation. The sole paratype is an adult male. It differs from the holotype in its smaller size (SVL 23.9 vs. 30.2 mm), broader tongue (nearly round without posterior notch vs. narrowly oval with posterior notch), presence of small, pale brown, finely granular nuptial pads on Finger 1, and of long vocal slits located laterally in floor of mouth extending from approximately angle of jaws halfway to front of mouth. Colour of paratype in life ( Fig. 2B View FIGURE 2 ) differs from holotype in having dorsal and lateral surfaces ivory overlain by dense stippling of dark brown, green spots larger, more extensive on head, tending to coalesce on snout such that snout is substantially green; ‘V’ shaped brown pigment patch on head present but less well defined than on holotype. Brown venation on iris finer than that of holotype, with several small brown pigment patches present (vs. absent) ( Fig. 2 View FIGURE 2 ).

Measurements of paratype: SVL 23.9; TL 13.1; HL 8.0; HW 7.1; EYE 3.0; TYM 1.1; EN 2.1; IN 2.4; 4TD 1.0; 4TP 0.8; 3FD 1.2; 3FP 0.8; TL/SVL 0.55; HW/HL 0.89; TYM/EYE 0.37; EN/IN 0.88; 3FD/4TD 1.2.

Advertisement call. Two calls produced by the male paratype at an air temperature of 22.6°C were recorded. They comprised a series of 11 and 10 harsh, distinctly pulsed chattering notes lasting 0.35 and 0.37 s ( Fig. 3 View FIGURE 3 ). Note lengths for both calls combined were 0.011 – 0.023 s (mean = 0.018, SD = 0.002, n = 21) and notes contained 4–12 pulses (mean = 9.3, SD = 1.71, n = 20; pulses were insufficiently resolved to count in one note). However only one note contained 4 pulses, the remainder contained 7–11 pulses. Pulse rate within notes was 300–647 pulses/s (mean = 484.65, SD = 71.46, n = 20) and notes within calls were produced at a rate of 27–29 notes/s with dominant frequency at 3400 and 3600 Hz for the two calls. A single call containing 11 notes is illustrated in Fig. 3 View FIGURE 3 .

Comparisons. In its small size (male SVL 23.9 mm, female 30.2 mm), slender body, green and brown dorsal colour, extensively webbed fingers, and lacking a rostral spike, Litoria daraiensis sp. nov. most closely resembles the following eight species: L. aplini Richards & Donnellan, 2020 , L. iris (Tyler, 1962) , L. majikthise Johnston & Richards, 1994 ; L. nigropunctata (Meyer, 1875) , L. richardsi Dennis & Cunningham, 2006 , L. singadanae Richards, 2005 , L. umarensis Günther, 2004 and L. verae Günther, 2004 . Richards & Donnellan (2020) provided a comprehensive table comparing morphological and acoustic features among all these species except L. nigropunctata and L. umarensis and we draw upon that table in the comparisons presented below. Litoria daraiensis sp. nov. is also morphologically similar to the other four new species formally described in this paper and is compared with them in the subsequent species accounts.

Litoria daraiensis sp. nov. differs from L. aplini by its smaller body size (an adult male 23.9 mm vs. males 31.9–35.1 mm SVL), less prominent dermal fold along outer edges of limbs, hidden surfaces of limbs predominantly yellow (vs. predominantly blue with dark-brown mottling), and advertisement call a series of 10–11 distinctly pulsed chattering notes (vs. advertisement call a short buzz normally followed by 1–7 clicks); from L. iris by its smaller size (male L. iris 25–35 mm SVL), hidden surfaces of limbs predominantly yellow (vs. posterior of thighs blue, red, or yellow, frequently blotched with white or purple), violet spots in axilla and groin absent (vs. present) and advertisement call a series of 10–11 distinctly pulsed chattering notes (vs. advertisement call a series of up to 10 notes of variable length, with long notes preceding or following short notes); from L. majikthise by its smaller size ( L. majikthise males 30–35 mm SVL), having posterior surfaces of thighs yellow (vs. uniform red), by lacking a pearl-white post-ocular bar (vs. present), lacking violet patches on posteroventral surfaces of abdomen (vs. present) and advertisement call a series of 10–11 distinctly pulsed chattering notes (vs. advertisement call a single long (0.29– 0.36 s) or short (0.026 –0.080) note); from L. nigropunctata by its smaller size (male SVL 23.9 vs. 27–32 mm; Menzies 1972, 2006; Günther 2004), dermal folds along outer margins of tarsi well developed, distinctly crenulated (vs. dermal folds forming low dermal ridge), and advertisement call a series of 10–11 distinctly pulsed chattering notes (vs. advertisement call comprising an irregular succession of clicks and buzzes; Menzies 1972); from L. richardsi and L. singadanae in having a smaller (TYM/EYE 0.37–0.48 vs. 0.65–0.81), pigmented (vs. substantially transparent) tympanum, and further from L. richardsi in lacking (vs. having) irregular black lines on dorsum and extensive black markings ventrolaterally, and from L. singadanae in lacking (vs. having) extensive area of orange on posteroventral surfaces in life; from L. umarensis in its smaller size (male SVL 23.9 vs. 26.3–30.3 mm SVL), posterior surfaces of thighs yellow (vs. brown), dorsum brown with green spots (vs. normally uniform green) and advertisement call a series of 10–11 distinctly pulsed chattering notes (vs. advertisement call comprising 1–5, normally 2–3, notes); and from L. verae in its smaller size (male SVL 23.9 vs. 33–35 mm SVL), lacking (vs. having) small brown spots aligned transversely on dorsum and lacking (vs. having) extensive area of orange on posteroventral surfaces in life.

Distribution and ecology. Litoria daraiensis sp. nov. is currently known from a single location on the Darai Plateau in Gulf Province, southern Papua New Guinea ( Fig. 4 View FIGURE 4 ). The Darai Plateau is an extensive area of limestone karst in the Kikori River Basin and forms part of the Great Papuan Plateau. Both specimens were found in primary foothill rainforest. The female was perched at a height of 1.0 m on foliage over a small forest pool at night. The male was calling at night from a leaf 2.3 m high in a swampy area with a number of small forest pools. The female contains large (1.5–1.8 mm diameter) predominantly yellow eggs that are slightly but distinctly darker on the animal pole. It is likely that this species lays its eggs on leaves overhanging forest pools because the female contains large, pale eggs like those of some other arboreal-breeding species ( Menzies 1993), but this has not been confirmed.

IUCN Red List status. Litoria daraiensis sp. nov. is known from one locality in the Kikori River Basin ( Fig. 4 View FIGURE 4 ), where it occurs within one of the largest remaining areas of relatively undisturbed lowland forest on the island of New Guinea. However, logging operations are occurring widely within the lower Kikori basin so until the species’ distribution, habitat requirements and any potential threats are better documented we recommend that it be listed as Data Deficient by the IUCN.

Etymology. The name daraiensis refers to the type and only known locality of this species, the Darai Plateau in Southern Papua New Guinea.

Molecular divergences. Based on analyses of a 787 base pair alignment from the mitochondrial ND4 gene and flanking tRNA, L. daraiensis sp. nov. is most closely related to L. gracilis sp. nov. (average net genetic distance, dA, between the taxa of 0.08, Table 2 View TABLE 2 ). dA between sister species pairs in other groups of Litoria ranges from 0.04 to 0.25 ( Donnellan et al. 2021, Rowley et al. 2021).