Litoria ridibunda Donnellan & Catullo & Rowley & Doughty & Price & Hines & Richards 2023, sp. nov.
Creators: name: Donnellan, S. C.
name: Catullo, R. A.
name: Rowley, J. J. L.
name: Doughty, P.
name: Price, L.
name: Hines, H. B.
name: Richards, S. J.
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Amphibia
Anura
Pelodryadidae
Litoria
Litoria ridibunda

description: Litoria ridibunda sp. nov.
Western Laughing Tree Frog
Figs 4, 8, 9
urn:lsid:zoobank.org:act: D3EEB985-2C1A-452F-B132-5B2B329C674E
Holotype. NTM R36917, an adult male collected at Channel Island Road, outer Darwin, Northern Territory, Australia (-12.58; 130.95) on 3 January 2013 by Stephen J Richards.
Other material examined. See Supplementary Table S2.
Diagnosis. Distinguished from other Australian Litoria (except other members of the L. peronii Group, sensu Tyler & Davies 1978) by a combination of: vomerine teeth present; distinct tympanum; grey to brown dorsal colouration with dark variegations (Fig. 9); black shin; posterior thigh colouration comprising variously shaped yellow to orange or reddish spots on a muted dark brown to black background (Fig. 4); fingers with moderate webbing; fully webbed feet; and moderately expanded terminal discs on all digits (Figs 8, 9).
Can be distinguished from L. amboinensis, L. darlingtoni, L. everetti, L. rothii and L. tyleri by the colour patterns on the posterior thigh in life. Litoria ridibunda sp. nov. typically has a matt black or dark grey background with yellow, orange or reddish coloured well-spaced patches or linear arrangements of coalesced patches often on the lower margin of the posterior thigh. The matt black or dark grey background provides less contrast than is seen L. rothii. Litoria amboinensis typically has a cream and brown pattern. Litoria darlingtoni and L. rothii typically have an immaculate glossy black background with yellow or occasionally white patches with highly discrete margins, providing a strong contrast between the dark background and the coloured patches. Litoria everetti has an orange marbled pattern. Litoria tyleri typically has a predominately orange coloration with small dark blotches and spots.
The calls of L. ridibunda sp. nov. are longer and contain more notes per call (average of 0.5– 1.2 s call duration and 9–18 notes per call) than L. rothii (average of 0.3– 0.8 s call duration and 5–10 notes per call).
Litoria ridibunda sp. nov. can be distinguished from L. rothii and L. everetti by apomorphic nucleotide states at 31 and 26 sites, respectively, in the ND4 gene alignment (Table 2).
Dimensions of holotype (mm). SVL 46.3; TL 22.7, HL 14.9; HW 13.7; EN 4.1; IND 3.5; ED 4.5; IOD 9.4; TD 3.4; FLL 9.9; Fin3L 12.6; Fin3DW 2.6; PpFin3 1.4; Toe4L 19.9; Toe4DW 2; PpToe4 4 1.
Description of holotype. Head approximately as long as broad (HL/HW = 1.08), and approximately one third snout to vent length (HL/SVL = 0.32). Snout blunt when viewed from above and in profile. Nostrils more lateral than superior, closer to snout than to eye. Distance between eye and naris approximately equal to internarial span (EN/ IND = 1.17). Canthus rostralis gently curved. Eye relatively large, its diameter equal to eye to naris distance (ED/EN = 1.09). Pupil horizontal when constricted. Tympanum distinct, and oval with long axis vertical. Tympanum length three quarters eye diameter (TD/ED = 0.75). Moderately developed supratympanic fold, glandular in appearance, that partially obscures tympanic region. Vomeropalatines forming two short, prominently raised ridges or, occasionally, round clumps, each 0.5–1.0 mm wide, located midway between choanae. Each elevation has 2–6 (most commonly 4–6) small but distinct teeth. Tongue broadly oval to nearly round with shallow posterior notch. Vocal slits long, lateral, extending from approximately angle of jaws halfway to anterior tip of jaw.
Fingers long, broad, with moderate webbing between digits 2 and 3 and basal between 3 and 4. Subarticular tubercles prominent. Terminal discs expanded, extending well beyond lateral extremities of penultimate phalanx. Fingers in order of length 3>4>2>1. Hindlimb length moderate (TL/SVL = 0.49). Toes in order of length 4>5=3>2>1. Webbing reaches nearly to disc on toe 4 and to disc on other toes. Subarticular tubercles prominent. Inner metatarsal tubercle absent. Terminal toe discs expanded, extending well beyond lateral extremities of penultimate phalanx. Dorsum lightly shagreened. Abdomen, undersurface of thighs, submandibular area and lateral aspect of body mildly granular. Pectoral fold present.
Variation. Assessment of morphological variation is based on 85 individuals (Table 4, Supplementary Table S2). Mean SVL: females = 47.7 mm (n=16), males = 44.2 mm (n=69). Head length equal to head width (HW/HL = 0.9–1.1) and approximately one-third of SVL (HL/SVL = 0.3–0.4). Distance between eye and naris equal to internarial span (EN/IND = 0.7–1.7). Eye relatively large but variable in diameter (ED/EN = 0.8–1.8). Tympanum length variable (TD/ED = 0.6–1.1). Moderate webbing between fingers 3 and 4. Hindlimb length moderate (TL/ SVL = 0.4–0.6). Indistinct canthus rostralis in some individuals.
Dorsum either smooth, mildly granular or with low and infrequent tubercles. Limbs with low tubercles and mildly granular or sometimes smooth.
Colour in life. Posterior thigh mostly matt black to dark grey, with yellow marking varying from a few blotches to transverse patches with diffuse margins occupying between 20–70% of the posterior thigh (Fig. 4). Vent same colour as surrounding dorsal colours. Fore of thighs and groin with same colour and pattern as posterior thigh but separated from posterior thigh pattern by intrusion of dorsal colour along top surface of thigh. Immaculate muted black continues along outer margin of leg and sometimes proximally onto dorsal surface of foot. Axilla with immaculate black or black and yellow blotches.
Dorsum and head vary from uniformly bone to light brown with some degree of mottling with light or dark brown spots to large patches (Figs 8, 9). Upper surfaces of limbs with same colour and pattern as dorsum. Wrist sometimes with transverse black mark. Head with thin black stripe, varying in prominence, beginning at posterior margin of eye and continuous across the top of the tympanum to black patch in axilla. Lips usually immaculate. Small black spots sparsely present in some individuals on snout or canthus rostralis.
Chin and chest plain white, lower abdomen and ventral surface of limbs sometimes suffused with yellow or orange tones, otherwise plain white. Throat in calling males suffused with black. Upper iris brownish-red to reddish, lower iris grey to light brown.
Habitat and reproductive biology. Habitat notes from WAM specimens indicate a wide habitat preference within Kimberley populations: water bodies such as swamps with paperbarks and Pandanus, as well as vegetated creeklines, rocky creeks and waterfalls in sandstone or basalt, seasonally flooded grasslands and near human habitation such as shower blocks. Males will call from the edges of ponds or from vegetation up to 1–2 m (PD pers. obs.). Some individuals observed basking on the ground or in vegetation in full sun during the day (PD pers. obs.). The majority (>70%) of FrogID records of the species as documented by users were from lentic waterbodies including ponds and flooded areas. The species was recorded commonly in suburban backyards and rural areas (>60% of FrogID records of the species) and buildings (Tyler et al. 1983).
The peak calling season for the species is the Australian Monsoon Tropics summer wet season from October to February (>84% of all FrogID records of the species), but L. ridibunda sp. nov. has been recorded calling in all months of the year (<3% of all FrogID records in May–July).
Anstis (2013) described the morphology of the larvae of L. ridibunda sp. nov. from Mitchell Plateau, WA, Kununurra, WA, and Marrara and Micket Creeks near Darwin, NT in a composite description that also included larvae of L. rothii from Queensland without noting any significant differences among the samples. Tyler et al. (1983) described the breeding biology, eggs and larval morphology and development of the species (as L. rothii) in the Magela Creek system in western Arnhem Land.
Distribution. From the Kimberley region across northern Australia north of about 19°S east to Mt Isa and Normanton. Apparently introduced populations in Port Hedland and Karratha in the Pilbara region of WA (Gaikhorst & Foster 2022; PD pers. obs.).
It occurs in the following IBRA regions: Dampierland, Central Kimberley, North Kimberley, Ord Victoria Plain, Victoria Bonaparte, Daly Basin, Pine Creek, Darwin Coastal, Tiwi Coburg, Arnhem Plateau, Central Arnhem, Arnhem Coast, Sturt Plateau, Mitchell Grass Downs, Gulf Fall and Uplands, Gulf Coastal, Mount Isa Inlier, and Gulf Plains.
Etymology. The specific epithet, a Latin adjective, refers to the nature of the male advertisement call— “laughing” = ridibunda.
description: Published as part of Donnellan, S. C., Catullo, R. A., Rowley, J. J. L., Doughty, P., Price, L., Hines, H. B. & Richards, S. J., 2023, Revision of Litoria rothii (Anura: Pelodryadidae) from northern Australia, pp. 73-108 in Zootaxa 5352 (1) on pages 99-103, DOI: 10.11646/zootaxa.5352.1.3, http://zenodo.org/record/8406992