Bioacoustics of Amnihyla kikori

Advertisement call. We recorded 13 calls from four individuals. Calls were similar among all individuals and were combined for analysis. The call of Litoria kikori sp. nov. is a single loud, musical note, sounding like ‘ tink’, uttered from leaves and branches between 2 and> 5 m above the banks of large foothill streams. Calls are 0.03– 0.05 s long (mean = 0.04, SD = 0.008, n = 13); notes are not pulsed, but two notes are partially divided into two subpulses. Frequency is concentrated in two bands, one at about 3600 Hz and the other at 1800 Hz (Fig. 4 ). The higher band is dominant in 11 calls (3460–3660 Hz, mean = 3600, SD = 58.32) while the lower frequency was dominant in two calls produced by SAMA R 69992 . Calls were produced at 0.38–37.0 seconds. However, if a single rapidly repeated couplet produced by SAMA R 69991 ( 0.38 s interval) is excluded then inter-call interval is 11.9–37.0 seconds (mean = 17.8, SD = 8.0 s , n = 8). Males produced these single-note calls in bouts lasting for at least several minutes. An exemplar call from paratype SAMA R 72336 has been uploaded to iNaturalist ( https://www.inaturalist.org/observations/218063325 ).

Comparisons with other species. We emphasize comparisons with torrent-breeding Litoria because based on taxa genetically sampled so far (e. g., Richards et al. 2021 , 2023 ) they form a monophyletic group that is also ecologically distinctive. The new species can be distinguished from non torrent-breeding Litoria by the following combination of characters: dorsum mottled green and brown, skin tuberculate (Fig. 1 A – C ), canthus rostralis strongly curved and moderately sharply defined in dorsal view, snout-tip shallowly acuminate, webbing on fingers moderate, extending to distal subarticular tubercles on outside of fingers 2 and 3, and adult size moderate (male SVL 30–36 mm ). Litoria kikori sp. nov. can be distinguished from other torrent-breeding Litoria in New Guinea as follows: it is larger than L. amnicola Richards, Tjaturadi, Krey & Donnellan, 2021 , L. brongersmai (Loveridge, 1945) , L. lakekamu Richards & Bickford, 2023 , L. leucova ( Tyler, 1968 ) , L. megalops Richards & Iskandar, 2006 , L. napaea ( Tyler, 1968 ) , L. rara Günther & Richards, 2005 and L. rivicola Günther & Richards, 2005 (male SVL > 30 mm versus < 25 mm ); and further differs from L. amnicola , L. brongersmai , and L. napaea in having prominent vomerine teeth (versus indistinct, detectable only as slight bumps); from L. lakekamu and L. leucova in its green-and-brown-mottled dorsum (versus green); from L. megalops in having moderate finger webbing (versus absent), and in its smaller eye ( EYE / SVL 0.12–0.14 versus 0.14–0.17); and from both L. rara and L. rivicola by its longer hindlimbs ( TL / SVL > 0.59 versus <0.56) and green or brown dorsal colouration (versus predominantly grey or greyish brown). Litoria kikori sp. nov. is substantially smaller than L. angiana (Boulenger, 1915) (max male SVL < 40 mm versus> 50 mm ), and further differs in having the snout distinctly acuminate (versus relatively blunt) in dorsal aspect, canthus rostralis curved in dorsal view (versus straight), and dorsum and lateral edge of tarsus strongly tuberculate in life (versus relatively smooth). Litoria kikori sp. nov. differs from the following ten similar-sized or slightly larger torrent-breeding species – L. arfakiana (Peters & Doria, 1878) , L. becki (Loveridge, 1945) , L. bulmeri ( Tyler, 1968 ) , L. oenicolen Menzies & Zweifel, 1974 , L. fuscula Oliver & Richards, 2007 , L. macki Richards, 2001 , L. micromembrana (Tyler, 1963) , L. modica ( Tyler, 1968 ) , L. spinifera ( Tyler, 1968 ) and L. wollastoni (Boulenger, 1914) – in having moderately extensive finger webbing that extends to distal subarticular tubercle on fingers 2, 3, and 4 (versus at most basal webbing between fingers 3 and 4); and further differs from L. arfakiana , L. oenicolen , L. spinifera and L. wollastoni in its less sharply acuminate snout tip and lacking prominent spiniform tubercles on heel (and in L. spinifera across body); from L. becki in its extensively webbed toes (versus toes half-webbed); from L. bulmeri by lacking a dark brown to black lateral band on head and body (versus present); from L. fuscula in having prominent vomerine teeth (versus indistinct, detectable only as slight bumps), green and / or brown mottled dorsal colouration (versus dark brown with no obvious pattern), and in having small conical tubercles along heel (versus no tubercles); and from L. macki in having low, indistinct tubercles on eyelids (versus prominent and large) and dark purplish-brown colouration in groin (versus yellow). Litoria kikori sp. nov. can be distinguished from four similar-sized species with moderate webbing between the fingers as follows: from L. dorsivena ( Tyler, 1968 ) and L. hastula Oliver, Iskandar & Richards, 2023 by its green-and-brown mottled dorsal colouration (versus predominantly brown) and snout relatively rounded in lateral view (versus distinctly acuminate in both lateral and dorsal views); from L. pratti (Boulenger, 1911) by its curved canthus rostralis (versus straight) and slightly longer limbs ( TL / SVL > 0.59 versus <0.57); and from L. scabra Günther & Richards, 2005 by its longer limbs ( TL / SVL > 0.59 versus <0.56), hindlimbs with series of low lateral tubercles (versus a crenulated ridge), and green or green-and-brown mottled dorsal colouration (versus predominantly grey or greyish brown) ( Günther and Richards 2005 ). Litoria kikori sp. nov. is most similar to L. spartacus Richards & Oliver, 2006 (Fig. 2 A ) and is closely related to it (see below), but can be differentiated by its smaller size (male SVL 29.9–35.8 versus 35.6–37.4, female SVL 45.4 versus 51.1), narrower finger pads ( 3 FD / SVL 0.045 –0.052 versus 0.048 –0.062 ), narrower toepads ( 4 TD / SVL 0.037 –0.050 versus 0.052 –0.062 ) (Fig. 2 B ), distal subarticular tubercle of finger 4 wider than long and slightly bifid (versus roughly equal in width and length and not bifid) (Fig. 2 B ), groin in life unpigmented or light purplish (versus orange) (Fig. 2 C – E ), throat in males without brown mottling (versus typically with brown mottling) and call consisting of a single note repeated at 12–37 second intervals for at least several minutes (versus multiple notes in short series lasting 5–20 seconds; Richards and Oliver 2006 ).

Holotype . SAMA R 69990 ( SJR [ JCUNQ ] 3245), adult male with vocal slits and nuptial pads, calling when collected, Libano Sok , Hegigio River , Southern Highlands Province , Papua New Guinea ( 6.3989 ° S , 142.9761 ° E ; 250 m a. s. l. ), collected by Stephen Richards on 7 August 2003 . Paratypes . SAMA R 69986 ( SJR [ JCUNQ ] 3222), R 69987 ( SJR [ JCUNQ ] 3240), R 69988 ( SJR [ JCUNQ ] 3243), R 69989 ( SJR [ JCUNQ ] 3244, R 69991 – R 69992 ( SJR [ JCUNQ ] 3246–3247), QMJ 98371 ( JCUNQ [ SJR ] 3241), PNGNM JCUNQ [ SJR ] 3242), all males with same locality and collector details as holotype, collected between 4–7 August 2003 ; SAMA R 72336 ( SJR 14135 ), male , and R 72337 ( SJR 14141 ), female , Bifo Creek , Southern Highlands Province , Papua New Guinea ( 6.4483 ° S , 142.9597 ° E ; 360 m a. s. l.), collected by Stephen Richards on 2 and 4 August 2014 respectively .

Diagnosis. A species of Litoria that can be distinguished from all congeners by the following unique combination of characters: size moderate (male SVL 29.9–35.8); snout moderately long ( EN / IN 0.51–0.75), slightly pointed in dorsal view, truncate in lateral view; canthus rostralis curved in dorsal view, relatively sharply defined in lateral view; limbs long ( TL / SVL 0.59–0.68); finger webbing moderate, extending to distal subarticular tubercles between fingers 3 and 4; toe webbing extensive, reaching to disc or to intercalary cartilage at base of disc on all digits except toe 4; finger and toe discs moderately narrow ( 3 FD / SVL 0.04–0.05, 4 TD / SVL 0.04–0.05); dorsal skin finely rugose with numerous larger tubercles on exposed surfaces of torso; hindlimbs with low, crenulated dermal ridges on outer edges of tibiae and tarsi; heels with 2–3 low conical tubercles; vomerine teeth in two prominent raised clumps; vocal slits present in males; dorsal colouration mottled green and brown; hidden surfaces of shanks and groin purplish in life; and advertisement call a single loud, unpulsed musical note lasting 0.03– 0.05 s and produced at intervals of ~ 12–37 seconds for long periods.

Distribution and ecological notes. Known only from two locations, Libano Sok and Bifo Creek, located 6 km apart in the Kikori River basin along the southern slopes of the Central Cordillera of Papua New Guinea (Fig. 5 ). Males in the type series were calling from leaves between 2–4 metres above swift-flowing rivers in hill forest (Fig. 6 A ). The female paratype ( SAMA R 72337 ) was collected from a tree adjacent to Bifo Creek. Five large, yellow eggs measured in situ were 1.7–2.0 mm diameter in diameter. At Libano Sok Litoria kikori sp. nov. occurred in sympatry with one other torrent-breeding pelodryadid frog, the new species described below. No other torrent-dwelling Litoria were detected at Bifo Creek.