Litoria haematogaster, 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 : 167-170

Litoria haematogaster , sp. nov.

Red-bellied Treefrog

Figs 9–10

https://zoobank.org/ urn:lsid:zoobank.org:act:561826C8-153C-416D-8E79-2ED52E67B6CD

Holotype. SAMA R71702 ( FN SJR3205 ), adult female, Darai Plateau , Gulf Province, Papua New Guinea (7.1295°S, 143.6134°E; 435 m a.s.l.), collected on 29 July 2003 by S. Richards.

Diagnosis. Litoria haematogaster sp. nov. is distinguished from all other Litoria by the following unique combination of characters: size moderate (SVL of one female 38.4 mm); dorsum in life mottled pale and darker green with scattered brown spots; vomerine teeth present; fingers extensively webbed; tubercles around vent and along outer edge of tarsus and foot prominent, conical; hidden surfaces of legs and posterior surfaces of belly bright red; purple pigmentation on posterolateral surfaces absent; pigmentation on nictitating membrane restricted to narrow band at dorsal margin; and is genetically diagnosable from L. lisae sp. nov. at 65 sites and from L. majikthise at 40 sites in the 787 base pair alignment of mitochondrial ND4 gene and flanking tRNA ( Table 1 ).

Description of holotype. Adult female ( Figs 9–10 ) containing numerous moderately small (~ 1.5 mm diameter) eggs with dark pigment on animal hemisphere. Body moderately slender. Limbs moderately long (TL/SVL 0.56). Head moderately wide (HW/SVL 0.32), slightly less than length (HL/SVL 0.34, HW/HL 0.92). Vomeropalatines forming two short ridges between choanae, without detectable teeth. Tongue large, broadly oval, with distinct posterior notch. Snout rounded in dorsal view with truncate tip ( Fig. 10A ), steep, near vertical in lateral view ( Fig. 10B ); canthus rostralis broadly rounded, slightly curved; loreal region steep, slightly concave; lips slightly flared; nostrils much closer to tip of snout than eyes, oriented anterolaterally; internarial distance greater than distance from external naris to eye (EN/IN 0.81); eyes large (EYE/SVL 0.12), prominent, protruding in dorsal and lateral views; pupil horizontal, pigmentation on nictitating membrane restricted to narrow band along dorsal edge. Tympanum large (TYM/SVL 0.06), nearly half diameter of eye (TYM/EYE = 0.47), annulus prominent except dorsal edge obscured by thick, strongly curved supratympanic ridge.

Skin of dorsum and dorsal surfaces of limbs finely granular with numerous scattered larger tubercles ( Figs 9– 10 ); throat finely ridged anteriorly, becoming more coarsely ridged posteriorly; a broad band of large, unpigmented tubercles around outer margins of throat; chest and abdomen coarsely granular. Ventral surfaces of limbs mostly smooth except proximal 1/2 distance along posteroventral margins of thighs with numerous large tubercles, those closest to vent largest, with size decreasing distally ( Fig. 9B ); transverse row of tubercles forming short elevated ridge below vent; ventral to this ridge are four prominent conical tubercles, each measuring ~ 1.2 mm in height; outer edge of tarsus and foot with row of prominent near-conical white tubercles extending from heel to distal subarticular tubercle on Toe 5; heels with seven (left leg) and eleven (right leg) small, pale tubercles; single large but low pale tubercle ventrally on each leg at junction of tibia and tarsus; outer edge of forearm with row of small pale tubercles that grades into more prominent tubercles and short crenulated fold on outer edge of hand where tubercles reach distal subarticular tubercle on Finger 4.

Fingers moderately short with expanded terminal discs (3FD/SVL 0.06; 3FD/3FP 2.55) with distinct marginal grooves. Distal subarticular tubercles on fingers 2–4 and proximal subarticular tubercle on Finger 3 strongly bilobed, remaining tubercles unilobed ( Fig. 10C ); relative lengths of fingers: 3>4>2>1. Finger webbing thick, fleshy, with deep creases forming fleshy ‘nodules’ ( Fig. 10C ); webbing on inside of Finger 4 reaching to midpoint between distal subarticular tubercle and disc, then extending to disc as fleshy fringe; on outside of Finger 3 reaching to midpoint between distal subarticular tubercle and disc ( Fig. 10C ), on inside of Finger 3 reaching to base of proximal subarticular tubercle, on outside of Finger 2 reaching to base of disc, and between fingers 1 and 2 reduced to basal fringe. Hand with low, elongate (1.5 mm long) inner, and broad (1.7 mm wide) outer, metacarpal tubercles, the latter partially subdivided into four by deep ridges ( Fig. 10C ). Toes with expanded terminal discs with terminal grooves, those on toes slightly smaller than on fingers (3FD/4TD 1.15). Distal subarticular tubercles on toes 4–5 bilobed, remainder unilobed; relative lengths of toes 4>5>3>2>1. Toe webbing thick, fleshy, on inside of Toe 5 reaching to base of disc, on both sides of Toe 4 to distal subarticular tubercle, on outside of Toe 3 to base of disc, on inside of Toe 3 halfway to base of distal tubercle, on outside of Toe 2 to base of disc, on inside of Toe 2 halfway to proximal tubercle and on outside of Toe 1 to distal tubercle ( Fig. 10D ). Foot with prominent, elongate inner metatarsal tubercle, outer tubercle not detectable.

Colour in life ( Fig. 9 ). Dorsal and lateral surfaces lime green with darker green flecks and reticulations; scattered pale brown spots across dorsum and on dorsal surfaces of limbs, hands and feet. Ventrally white anteriorly with fine brown stippling on throat, posteriorly abdomen bright red; hidden and ventral surfaces of legs, and axillae, uniform red, except for enlarged ivory tubercles on underside of limbs and around vent; heels white; feet predominantly brown dorsally, hands predominantly green dorsally; outer edges of tarsi and feet, and of forearm, with fine dark brown stippling. Iris pale grey with dark brown veins and pale-yellow rim around pupil.

Colour in preservative. In preservative dorsal and lateral surfaces paler and darker blue; dorsal surfaces of fingers 1 and 2 ivory; brown patches on dorsal surfaces of arms still visible, brown pigmentation in life now darker brown; red areas in life pinkish. Ventrally mid-abdomen ivory, ventral surfaces of arms creamy. Throat creamy white with dense brown stippling except on enlarged creamy-white tubercles. Hands ventrally translucent grey blue.

Measurements of holotype (in mm).— SVL 38.4; TL 21.5; HL 13.2; HW 12.2; EYE 4.7; TYM 2.2; EN 3.5; IN 4.3; 4TD 2.0; 4TP 1.5; 3FD 2.3; 3FP 0.9; TL/SVL 0.56; HW/HL 0.92; TYM/EYE 0.47; EN/IN 0.81; 3FD/4TD 1.15.

Variation. The holotype is the only known specimen.

Comparisons. In its moderate size (a female 38.4 mm), slender body, green and brown dorsal colour, and extensively webbed fingers, Litoria haematogaster sp. nov. most closely resembles the following 10 species: L. aplini , L. daraiensis sp. nov., L. gracilis sp. nov., L. iris , L. majikthise , L. nigropunctata , L. richardsi , L. singadanae , L. umarensis and L. verae . Litoria haematogaster sp. nov. is also morphologically similar to the two new species described below and is compared with them in the relevant species accounts.

Litoria haematogaster sp. nov. differs from L. aplini by having discrete prominent conical tubercles along the tarsus and foot (vs. a crenulated dermal fold), and hidden surfaces of limbs red (vs. predominantly blue with dark-brown mottling); from L. iris by having hidden surfaces of limbs and posterior surfaces of abdomen red (vs. posterior of thighs blue, red, or yellow, frequently blotched with white or purple, posterior surfaces of abdomen not red), and violet spots in axilla and groin absent (vs. present); from L. nigropunctata by having prominent conical tubercles along the tarsus and foot (vs. a low dermal ridge), and hidden surfaces of limbs and posterior surfaces of abdomen red (vs. yellow); from L. richardsi and L. singadanae in having a smaller (TYM/EYE 0.46 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; from L. umarensis and L. verae in having prominent conical tubercles on tarsus and foot (vs. absent), and further from L. umarensis in having posterior surfaces of thighs red (vs. brown), and dorsum mottled lighter and darker green (vs. normally uniform green); and further from L. verae in lacking (vs. having) small brown spots aligned transversely on dorsum, and having red (vs. orange) on posteroventral surfaces in life.

The new species is morphologically most similar to L. majikthise from which it is genetically divergent (dA between the taxa of 0.08) and from which it can most readily be distinguished by having more prominent conical tubercles on the limbs and around the vent (vs. tubercles lower, rounded; e.g., Fig. 9B vs. Fig. 2B in Johnston & Richards (1994)), violet patches in axillae absent (vs. present), and head longer (HL/HW 1.08 vs. 0.81–1.03).

Distribution and ecology. Litoria haematogaster sp. nov. is known only from a single location on the Darai Plateau in Gulf Province, southern Papua New Guinea ( Fig. 4 ). The Darai Plateau is an extensive area of limestone karst in the Kikori River Basin and forms part of the Great Papuan Plateau. The holotype was found in primary foothill rainforest where it was perched at a height of 3.5 m on a sapling in a swampy area with small forest pools. It contains moderate-size (1.5 mm diameter) eggs with a distinctly darker animal pole. The reproductive biology of this species is unknown.

IUCN Red List status. Litoria haematogaster sp. nov. is known from one locality on the Darai Plateau, which supports an extensive tract of lowland forest in the Kikori River basin. However, logging operations are occurring widely within this catchment 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. From the Greek haema ‘blood’, and ‘gaster’, belly, referring to the bright red colour of the posteroventral surfaces of this species.

Molecular divergences. Based on analyses of a 787 base pair alignment from the mitochondrial ND4 gene and flanking tRNA, L. haematogaster sp. nov. is most closely related to L. majikthise (dA between the taxa of 0.08, 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). Our molecular data also suggests potential structure across the two sampled populations of L. majikthise ( Fig. 18 ; dA of 0.07), but in the absence of additional acoustic and morphological evidence for differentiation we conservatively consider all these populations to be conspecific at this stage.

Figures

FIGURE 2. Litoria daraiensis sp. nov. in life, A) holotype (SAMA R71675), B) paratype (SAMA R71676). Photos by S. Richards

FIGURE 4. Map showing the distributions of Litoria species newly described species in this paper, and Litoria singadanae from the Huon Peninsula, Papua New Guniea. Blue square = Litoria daraiensis sp. nov., yellow triangle = Litoria gracilis sp. nov., red circle = Litoria haematogaster sp. nov., pale blue circles = Litoria lisae sp. nov., pink diamond = Litoria naispela sp. nov. and purple diamond = Litoria singadanae. Arrows indicate the type localities for Litoria gracilis sp. nov. and Litoria lisae sp. nov..

FIGURE 9. Litoria haematogaster sp. nov. holotype (SAMA R71702) in life, A) lateral and B) ventral views. Photos by S. Richards.

FIGURE 10. Litoria haematogaster sp. nov. holotype (SAMA R71702), A) dorsal and B) lateral view of head (scale bars = 5 mm), C) palmar view of hand, D) plantar view of foot (scale bars = 1 mm).

FIGURE 18. Maximum Likelihood phylogeny of mitochondrial ND4 sequences for the main radiation of Melanesian Litoria including the five new species described in this paper (taxon labels in bold), estimated using IQTree. Node support values (bootstrap proportions) below 70 are not provided. Branches leading to taxa known to exhibit arboreal breeding are highlighted in red.