Litoria vivissimia, Oliver & Richards & Donnellan, 2019

Oliver, Paul M., Richards, Stephen J. & Donnellan, Stephen C., 2019, Two new species of treefrog (Pelodrydidae: Litoria) from southern New Guinea elucidated by DNA barcoding, Zootaxa 4609 (3), pp. 469-484 : 474-479

Litoria vivissimia sp. nov.

Montane Pinocchio Frog

Figs. 5–7 .

Holotype. SAMA R71127 (Field number SJR 9077 ), Hides Ridge , Hela Province, Papua New Guinea (5.9470°S, 142.7455°E; 2250 m a.s.l.), collected by Stephen Richards and Ted Mamu on 12 October 2005.

Diagnosis. Litoria vivissimia sp. nov. can be distinguished from all other Litoria by the following combination of: a long (up to at least 1.8 mm) erectile rostral spike in males; relatively small size (SVL of male holotype 28.6 mm); very slender build (HW/SVL 0.26), moderately long limbs (TL/SVL 0.52); large eyes (EYE/SVL 0.11); moderately large tympanum (TYM/SVL 0.049); rugosity on ventral skin of thigh extending more than half-way from cloaca to knee; white skin crenulations along outer edge of ankle moderately prominent; dorsum light yellowish brown in life with extensive light-green tubercles and blotches; concealed parts of thighs and axilla yellow; and dorsal and ventral edges of lateral flanges on shank with extensive white flecking.

Description of holotype. Adult male with vocal slits and brown nuptial pads. Body very slender, limbs short (TL/SVL 0.52), head wider than body in dorsal profile (HW/SVL 0.26), distinct from neck. Snout truncate in dorsal and lateral views, with distinct, moderately long rostral spike extending from tip of upper jaw (RL/SVL = 0.086), diameter of spike at base over a third internarial span. Canthus rostralis moderately well defined, slightly curved, loreal region concave. Nares round, closer to tip of snout (excluding spike) than to eye, oriented laterally, close to top of snout, not visible dorsally. Eyes large (EYE/SVL 0.11), protruding in both dorsal and lateral aspect, pupil horizontal. Upper jaw protruding marginally beyond lower jaw. Tympanum moderately distinct (EAR/SVL 0.050), bordered dorsally by fleshy supratympanic fold extending to superior edge of insertion of upper arm. Choanae small, circular, close to anterior and lateral edge of palate; no vomerine teeth; tongue fleshy and ovoid. Vocal slits under posterior edge of tongue, close to rictus of jaws. Dorsal skin with numerous scattered small tubercles; ventral skin coarsely granular on throat, abdomen and upper- to mid-hindlimbs; remaining ventral surfaces of limbs smooth; unpigmented ventral tubercles concentrated around vent, along posterior edge of hindlimbs and, to a lesser extent, along posterior edge of forelimbs; poorly developed lateral skin flanges on posterior and anterior forearms, and on shanks.

Fingers with relative lengths III>IV>II>I; fleshy opaque webbing between all digits; in a narrow basal strip between I and II, extending to disc on distal edge of II and proximal edge of IV, and to penultimate phalanx on both sides of III. Terminal discs expanded (3FD/SVL 0.052), wider than toe discs and with distinct marginal grooves. Nuptial pads medium brown, approximately half length of finger I, roughly tear-shaped, with point of tear oriented ventro-posteriorly. Single unpigmented subarticular tubercle present at base of each penultimate phalanx, rounded on fingers I–II, bifid on III–IV; additional indistinct, unpigmented subarticular tubercles present on fingers II–IV as follows: single very indistinct proximal metacarpal tubercles present at base of I, and two smaller distal metacarpal tubercles at base of III and IV.

Toes with relative lengths IV>III>V>II>I. All digits with extensive fleshy opaque webbing, basal between I and II, extending to anterior edge of penultimate phalanx of II and III and inner edge of V, to halfway along penultimate phalanx on proximal edge of III and IV, and base of penultimate tubercle on outer edge of IV. Terminal discs slightly expanded (4TD/SVL 0.045), narrower than finger discs and with distinct marginal grooves. Plain offwhite, indistinct subarticular tubercles on penultimate phalanx of all toes, single on I–III, bifid on IV and V; metatarsal tubercle single, small, indistinct, unpigmented and present at base of I.

In preservative, dorsum buff with extensive bluish ocelli or blotches, surrounded by dense dark-grey to black maculations, with a further moderately distinctive jagged light-blueish-green transverse pre-orbital band. Dorsal surfaces of arms, thighs and shanks similarily patterned, but with distinctive light buff and sparsely patterned lateral margins. Dorsal surfaces of digits and ankles sparsely patterned with fine dark-grey maculations, tending to be denser on outer digits. Venter light buff, largely unpatterned except for some clusters of dark-brown maculations around margins of throat and towards tips of digits ( Fig. 5 ).

Summary meristic data for holotype. All measurements in mm: SVL 28.6 ; SVL1 30.4; TL 15.0; HW 7.3; HL 10.4; EYE 3.2 ; TYM 1.4 ; IN 2.6; EN 2.5; 3FD 1.5; 3FP 1.0; 4TD 1.3; 4TP 0.9; RL 1.8.

Colouration in life. The following description is based on a photograph ( Fig. 6A ) of the holotype. Dorsum light yellowish brown with an olive-green jagged transverse pre-orbital band, further light-green flecking on head, dorsal tubercles and exposed portion of limbs, moderately prominent white tubercles scattered along outer edge of ankle, and inner groin yellow.

Comparisons. The combination of small adult size (<28.6 mm without the rostral spike), slender build and a rostral spike distinguishes Litoria vivissimia sp. nov. from all but five Melanesian Litoria . Litoria vivissimia sp. nov. can be distinguished from three of these as follows: from L. mareku by its larger size (adult male SVL 28.6 vs 25.5–26.5 mm), mottled yellowish-brown and light green dorsal colouration in life (vs much darker brown), and the absence of a prominent blue rim around the iris (vs present) ( Günther 2008); from L. havina by its mottled brown and green dorsal colouration (vs plain green or brown), yellow groin colouration (vs red), tuberculate dorsum (vs smooth) and longer rostral spike; and from L. mucro in having dorsal and ventral edges of the lateral flanges on the shank with extensive white flecking (vs with no or little white flecking) and in having exposed areas of the shanks and forearms flecked and blotched with olive-green (vs brown reticulations) and a longer rostral spike in males (1.8 vs 0.8–1.2 mm).

Litoria vivissimia sp. nov. is most similar in size and appearance to L. pinocchio from the Foja Mountains and L. pronimia from the southern slopes of the Central Cordillera ( Fig. 6B ). It differs from L. pinocchio in having longer limbs (TL/SVL 0.52 vs 0.48), a smaller tympanum (TYM/SVL 0.049 vs 0.055), extensive olive-green tubercles across the dorsum (vs on lateral regions only), and white crenulations and tubercles along the outer edge of the ankle (vs absent). It differs from L. pronimia (including genotyped samples from Gulf Province, and others from near the type locality at Tabubil in Western Province) mainly in aspects of colouration and tuberculation ( Fig. 7 ) including: dorsal and ventral edges of the lateral flanges on the shanks with extensive white flecking and tubercles (vs with no or little white flecking), and rugose skin on the ventral surface of the thigh extending more than half the distance from the cloaca to the knee (vs extending less than half way). Based on comparison of preserved material of Litoria vivissimia sp. nov. and L. pronimia ( Fig. 7 ) the former also has prominent and larger blue (green in life) blotches on the dorsal surface of upper arms, forearms, thighs and shanks (vs mottled light and dark), more extensive white flecking on the dorsal and ventral edges of lateral flanges on the shank, and only sparse dark-brown maculations on the digits and ankles (vs dense).

Molecular differentiation. Based on morphology (see diagnoses above) Litoria vivissimia sp. nov. could most easily be confused with L. mucro , L. pinocchio or L. pronimia . Genetic data are not available for L. pinocchio . Mean p-distances between Litoria vivissimia sp. nov. and both L. mucro and L. pronimia are 0.19 (n= 2 in both cases), while p-distances between L. mucro and L. pronimia are lower (0.16).

Distribution and ecology. This species is known only from a single locality on Hides Ridge, Hela Province, in the karstic Southern Fold Mountains that run along the southern edge of New Guinea’s Central Cordillera ( Fig. 8 ). The holotype was collected from a small pond at 2250 m. a.s.l. in primary mid-montane rainforest on karst ( Fig. 9 ). Despite repeated visits to this site in the ensuing decade, this species has not been observed again, although calls that may represent this species have subsequently been recorded at the type locality using remote recording devices ( Richards & Armstrong 2017). In contrast, another small treefrog, Litoria iris , was abundant at the same pond on multiple visits, raising the possibility that this species may be competitively excluding Litoria vivissimia sp. nov.

IUCN Status. Litoria vivissimia sp. nov. is known only from a single location, but extensive apparently suitable habitat occurs in the region so until this species’ distribution has been better documented we recommend that it be listed as Data Deficient.

Etymology. A compound noun in apposition from the Latin “vivis” for “cheeky” and “simia” for “monkey”, in reference to the elusive nature and presumably treetop habitat of this species, and further in honour of the senior author’s wife for whom the epithet is also somewhat appropriate.

Remarks. The type locality of Litoria vivissimia sp. nov. is the highest known location for any small spike- nosed Litoria recorded to date. The highest previous record is 1000 m lower (1250 m a.s.l.) for L. pinocchio in the Foja Mountains ( Oliver et al. 2019). All spike-nosed treefrogs (excluding the morphologically distinct Litoria prora complex) that we have examined from lower elevations (between 300–1130 m a.s.l.) in nearby Gulf and Western Provinces, are attributed to L. pronimia on the basis of their consistent morphology and colouration. Genotyped samples from Agogo and Gobe (respectively 60 and 140 km east of the type locality of Litoria vivissimia sp. nov.) are also morphologically consistent with topotypic L. pronimia . These animals show a deep genetic divergence from the new species, as noted above.

A number of frogs and lizards in the Southern Fold Mountains of New Guinea are currently known only from forests on karst ( Richards & Oliver 2010; Oliver et al. 2012; Nielsen & Oliver 2017). The possibility that Litoria vivissimia sp. nov. is part of a previously overlooked specialist karst forest biota in this region warrants further investigation.

Figures

FIGURE 5. Holotype of Litoria vivissimia sp. nov. SAMA R71127 in preservative. Scale bar 10 mm. Photographs by Peter Waddington, Queensland Museum.

FIGURE 6. Images in life of a) Litoria vivissimia sp. nov. SAMA R71127 and b) Litoria pronimia uncollected specimen, Tabubil, Western Province. Photographs by S. Richards.

FIGURE 7. Comparisons of preserved holotype of Litoria vivissimia sp. nov. (far left) and Litoria pronimia from near the type locality at Tabubil (SAMA R71135–6, 71140) and the Kikori River Basin (SAMA R77131). Note more solid green colouration on the dorsum and limb of the new species. Photograph by Peter Waddington, Queensland Museum.

FIGURE 8. Distribution of Litoria vivissimia sp. nov., Litoria pronimia and Litoria pinocchio.

FIGURE 9. Mid-montane forest habitat of Litoria vivissimia sp. nov. on Hides Ridge, 2250 m a.s.l., Hela Province, Papua New Guinea. Photograph by S. Richards.