Oreophryne gagneorum, Kraus, Fred, 2013

Kraus, Fred, 2013, Three new species of Oreophryne (Anura, Microhylidae) from Papua New Guinea, ZooKeys 333, pp. 93-121 : 106-112

Oreophryne gagneorum sp. n. Figs 2E, F, 6

Holotype.

BPBM 20542 (field tag FK 10121), adult female, collected by F. Kraus and local villagers on S slope of Mt. Rossel, 11.3555°S, 154.2246°E, 720 m, Rossel Island, Milne Bay Province, Papua New Guinea, 5 May 2004.

Paratypes

(n = 52). Same data as holotype (BPBM 20538-41, 20543-57, PNGNM 24153-55); same data as holotype, except collected 3 May (BPBM 20531-37), 6 May (BPBM 20558-60, PNGNM 24156-60), 7 May (BPBM 20561-69), 8 May (BPBM 20570), 9 May (BPBM 20571), and 10 May (BPBM 20572) 2004; halfway between 11.3354°S, 154.2223°E and 11.3354°S, 154.2247°E, 275-280 m (BPBM 43075, PNGNM 24161).

Diagnosis.

Oreophryne gagneorum can be distinguished from all congeners by its unique combination of small size (adult male SV = 16.3-20.0 mm, adult female SV = 19.0-23.5 mm); cartilaginous connection between the scapula and procoracoid; well-webbed toes; third and fifth toes subequal in length; steeply oblique lores; leg moderately long (TL/SV = 0.46-0.59); snout typically longer than broad (EN/IN = 1.00-1.33, EN/SV = 0.093-0.121, IN/SV = 0.080-0.109); head relatively broad (HW/SV = 0.36-0.43, HL/HW = 0.82-0.92); tympanum small (TY/SV = 0.034-0.051); finger and toe discs relatively broad (3rdF/SV = 0.063-0.086, 4thT/SV = 0.048-0.066, 3rdF/4thT = 1.18-1.47); shanks either unicolor or flecked/mottled with dark brown; pale-tan iris suffused or veined with black; and call a rapid series of short notes (23-190 ms) delivered at a rate of 9.57-11.32 notes/s with a dominant frequency of 3070-3510 Hz.

Comparisons with other species.

The new species differs from all other Papuan Oreophryne except Oreophryne crucifer and Oreophryne kampeni in its unique combination of having a cartilaginous connection between the scapula and procoracoid and having well-webbed toes. Oreophryne gagneorum differs from Oreophryne crucifer in its longer leg (TL/SV = 0.46-0.59 vs. 0.45 in Oreophryne crucifer ), longer snout (EN/SV = 0.093-0.121 vs. 0.092 in Oreophryne crucifer ), shorter head (HL/HW = 0.82-0.92 vs. 0.78 in Oreophryne crucifer ), smaller tympanum (TY/SV = 0.034-0.051 vs. 0.054 in Oreophryne crucifer ), relatively wider finger discs (3rdF/4thT = 1.18-1.47 vs. 1.13 in Oreophryne crucifer ), fourth finger longer than the second (second longer than fourth in Oreophryne crucifer ), and absence of a golden-yellow bar between the eyes. It differs from Oreophryne kampeni in having the third and fifth toes subequal in length (third distinctly longer in Oreophryne kampeni ), more oblique loreal region (lores almost vertical in Oreophryne kampeni ), usually longer leg (TL/SV = 0.46-0.59 vs. 0.44-0.47 in Oreophryne kampeni ) and longer snout (EN/IN = 1.00-1.33 vs. 0.094-1.05 in Oreophryne kampeni ), larger toe discs (4thT/SV = 0.048-0.066 vs. 0.042-0.048 in Oreophryne kampeni ), and the shanks without brown spots (shanks conspicuously patterned with round dark-brown spots in Oreophryne kampeni ).

Oreophryne cameroni , Oreophryne idenburghensis , Oreophryne oviprotector , and Oreophryne waira also have a cartilaginous connection between the scapula and procoracoid and webbing between the toes, but they differ from Oreophryne gagneorum in having basal instead of extensive toe webbing. Furthermore, Oreophryne cameroni has the fifth toe distinctly longer than the third, a shorter snout (EN/IN = 0.94-0.95 vs. 1.00-1.3 in Oreophryne gagneorum ), dark-brown iris, and call consisting of more slowly delivered notes (2.64-2.75 notes/s vs. 9.57-11.32 notes/s in Oreophryne gagneorum ) of lower dominant frequeny (2870-2940 Hz vs. 3070-3510 Hz in Oreophryne gagneorum ). Oreophryne idenburghensis is a much larger species (SV = 43-47 mm vs. 16.3-23.5 mm in Oreophryne gagneorum ), with the fifth toe distinctly longer than the third, and with a broader snout (EN/IN = 0.087-0.091 vs. 1.00-1.33 in Oreophryne gagneorum ); Oreophryne oviprotector has the fifth toe distinctly longer than the third, is lime green dorsally with a green bar between the eyes and a white ring around the orbit, and has a rattle call; and Oreophryne waira is a slightly smaller species (SV = 17.8-21.0 mm vs. 16.3-23.5 mm in Oreophryne gagneorum ) with a rattle call (vs. a high-pitched whinny in Oreophryne gagneorum ) and a shorter snout (EN/IN = 0.094-0.105 vs. 1.00-1.33 in Oreophryne gagneorum ). All other Papuan Oreophryne have either a ligamentous connection between the scapula and procoracoid, lack toe webbing entirely, or both.

Description of holotype.

An adult female with an incision on right side and left pectoral region dissected. Procoracoid connected to the scapula by a narrow cartilaginous rod. Head wide (HW/SV = 0.40), with steeply oblique loreal region; upper lip inflated. Canthus rostralis rounded, straight when viewed from above (Fig. 6A). Nostrils directed laterally, much closer to tip of snout than to eyes. Internarial distance slightly wider than distance from naris to eye (EN/IN = 1.25, IN/SV = 0.085, EN/SV = 0.106). Snout truncate when viewed from the side (Fig. 6B), shallowly angulate when viewed from above (Fig. 6A). Eyes moderately large (EY/SV = 0.14); eyelid approximately two-thirds width of interorbital distance. Tympanum small (TY/SV = 0.034), but with a distinct annulus, partly covered by skin posterodorsally. Weak supratympanic fold present; another weak fold extends posteroventrally from rear margin of tympanum. Skin smooth above and below, except abdomen granular. Fingers unwebbed, bearing discs with terminal grooves; relative lengths 3>4>2>1 (Fig. 6C). Finger discs approximately twice width of penultimate phalanges except for F1, which is approximately 1.5 times as wide as penultimate phalanx (3rdF/SV = 0.074). Subarticular tubercles low but distinct; inner metacarpal tubercle a large, low oval; outer a low circle. Toes well webbed, formula I 2-2 II 2.7-3.6 III 3-4.5 IV 4.7-3.6 V; bearing discs with terminal grooves; relative lengths 4>5=3>2>1 (Fig. 6D). Toe discs smaller than those of fingers (4thT/SV = 0.060, 3rdF/4thT = 1.24), approximately 1.5 times width of penultimate phalanges. Subarticular tubercles low but distinct; inner metatarsal tubercle a narrow oval; outer not apparent. Hind legs rather long (TL/SV = 0.49).

In preservative, dorsum pale tan minutely speckled with brown, with a narrow, partially obscured tan vertebral line; limbs, including rear of thighs, same color as dorsum. Pale patch of lighter tan extends between eyes, narrowly margined posteriorly by dark brown. Short pale-cream dash extends from behind eye, through tympanum, to end near forearm insertion; this is bordered above and below by small, diffuse fields of brown. Lateral and ventrolateral surfaces suffused with pale cream. Venter pale straw yellow minutely stippled with brown, this more concentrated on chin and throat, somewhat sparser posteriorly; under limbs, hands, and feet stippled likewise. Sparse brown canthal stripe and subocular blotch present. Iris pale tan veined with black, which is especially concentrated in a horizontal plane before and behind the pupil.

Measurements of holotype (in mm).-SV = 23.5, TL = 11.6, HW = 9.5, HL = 8.3, IN = 2.0, EN = 2.5, SN = 3.5, EY = 3.2, TY = 0.8, 3rdF = 1.73, 4thT = 1.40, mass = 1.20 g.

Variation.

The only apparent sexual dimorphism in this species is in size; females are larger than males in both mass and SV (Table 4). Otherwise, standard deviation of variables largely accords with the size of the mensural character, and variation across most variables is tight (Table 4). The snout shape varies from truncate to slightly rounded in lateral view and from shallowly angulate to slightly rounded in dorsal view. The tympanum is usually partially embedded in the surrounding skin, giving the impression that it sits in a depression. Webbing between the toes is always well developed, as in the holotype, and never merely basal. In life, animals have obvious scattered tubercles (Fig. 2E, F), but these become obscure in preservative.

This species presents a diverse array of color patterns in brown and gray. The dorsum varies from pale tan to dark brown, and may be uniform in pattern but more often with ill-defined dark smudges or suffusions of dark color that frequently form a vague, paler hourglass pattern mid-dorsally and/or a poorly defined, dark scapular W. Occasionally, there will be a large orange-tan blotch mid-dorsally, usually on the posterior half of the dorsum; there are also orange-tan blotches on the heels of two specimens. The pale cream or tan postocular dash is always present and extends through the tym panum; this is invariably bordered above by a dark-brown dash followed by a brief hiatus and another short brown dash over the forearm insertion. There is typically a diffuse dark-brown field below the cream postocular stripe; occasionally this is better developed into another brown dash or blotch. The dark-brown canthal stripe and subocular blotch may be present, absent, or only vaguely suggested. Top of the snout is often, but not always, paler than the remainder of the dorsum; there is often either a dark-brown or pale-tan bar extending between the eyes, but these too are variably present. A narrow, pale-tan vertebral line is present in 25 of the specimens; this is often broken or developed only anteriorly. Lumbar ocelli are almost always absent and are poorly developed in the few specimens in which they occur. Ventral ground color is typically pale straw yellow with the overlying dark pigment varying from minute and evenly distributed stippling to dense evenly distributed stippling to dense, aggregated dark stippling. Consequently, the impression of ventral coloration to the naked eye varies from evenly pale brown to evenly dark brown to pale brown with dark-brown flecks. Four specimens have poorly defined, pale-straw lines mid-ventrally on the chin and throat, and another four have pale-gray flecks scattered across the belly. Iris color is always pale tan either suffused or veined with black, this is usually concentrated in a horizontal plane before and behind the pupil.

Color in life.

Field notes for BPBM 20531 in life recorded the color as: "Dorsum brown with darker brown mottling and tan stripe laterally, below which is dark brown. Iris tan. Tan postocular stripe. Venter pale gray stippled with dark gray. Rear of thighs dark brown." BPBM 20532 was dark tan dorsally with a few dark-brown spots; the rear of thighs were the same as the dorsum. BPBM 20533 was also brown dorsally with vague brown markings, a pale tan postocular stripe, and a small amount of yellow in the groin. The rear of the thighs were brown with a few light-gray stipples. Chin to chest was dark gray with light-gray flecks, and the abdomen and undersides of the legs were light gray heavily flecked with dark gray. BPBM 20534 had a tan vertebral stripe and a dusky red patch in groin and front and rear of thighs. BPBM 20535 was chocolate brown dorsally with a cream postocular stripe, yellow in the inguinal region, and dusky brick red in groin and hidden surfaces of thighs. The holotype was pale tan-gray in life with a few, scattered red-brown spots (Fig. 2E); BPBM 20544 was dark brown with an orangish hourglass-shaped figure mid-dorsally, white-tipped tubercles, tan inter-ocular bar, and cream on the sides (Fig. 2F). Both of these animals exhibited silver irises with a reddish-brown horizontal bar through the pupil.

Call.

This species was the predominant frog calling around the summit of Mt. Rossel. I recorded 14 calls from six animals, and calls segregated into two types: a long and a short call (Table 5). The former was the most commonly produced call, with the shorter call being produced more frequently when conditions were drier. Note-delivery rate of both call types is so rapid that to the human ear calls sounds like a high-pitched whinny.

The more commonly delivered, long calls (n = 8) ranged from 1.98-2.92 s in duration and consisted of a series of 21-31 notes emitted at a rate of 10.30-11.02 notes/s (Table 5). The first note of each call was much longer than the remainder (Fig. 7A), being 143-190 ms in length (mean 167 ms); subsequent notes were much briefer, with a mean of means of 37 ms (range 23-56 ms). The interval between notes was somewhat longer than the notes themselves, with a mean of means of 53 ms and range of 29-82 ms. The first note had a rounded amplitude envelope initially, followed by a short, sharp drop in volume, quickly succeeded by a large terminal spike (Fig. 7A); subsequent notes attained maximum volume rapidly and then decreased at an increasing rate, resulting usually in a concavely triangular amplitude envelope (Fig. 7A). Notes lacked harmonics, pulsing, and frequency modulation (Fig. 7C). The dominant frequency of calls varied within a very narrow window (Fig. 7B), with a mean of means of 3337 Hz and range of 3212-3514 Hz.

The less-frequently delivered short calls (n = 6) contained only 9-12 notes but were emitted at a rate similar to that found in the longer calls (9.57-11.32 notes/s); calls ranged from 0.85-1.06 s in duration (Table 5). Notes of these calls were not so internally divergent in length as those in the long calls. For each call, the first note was only approximately twice the length of the remainder (Fig. 7D), being 92-112 ms in length (mean 102 ms), compared to a mean of means of 54 ms (range 46-62 ms) for subsequent notes (Table 5). The interval between notes was shorter than in the long calls, with a mean of means of 37 ms and range of 26-44 ms. Hence, the length difference between notes and inter-note intervals was not as great as seen in the long calls. The first note attained maximum volume rapidly, decreased rapidly to a lower amplitude, and then maintained that until the end of the note (Fig. 7D); subsequent notes also increased to maximum amplitude quickly, maintained that volume rather evenly, and then decreased quickly to termination, producing an approximately square-shaped amplitude envelope (Fig. 7D). Notes lacked harmonics, pulsing, and frequency modulation (Fig. 7F). The dominant frequency of calls varied within a very narrow window (Fig. 7E), with a mean of means of 3289 Hz and range of 3068-3497 Hz.

Etymology.

The name is an honorific for Betsy and Wayne Gagné, dedicated and inspiring conservationists of Pacific island biotas and among the few western researchers to visit Mt. Rossel, being members of the 1979 Lae Forestry Institute botanical expedition to that mountain.

Range.

Endemic to Rossel Island, Milne Bay Province, PNG. It was very common along the upper elevations of Mt. Rossel at 720-750 m elevation, but I found it to occur as low as 280 m elevation.

Ecological notes.

The type locality consists of dense cloud forest on a steep ridge on the south slope of Mt. Rossel. Forest here is approximately 5-10 m high, and large gingers and tree ferns are common. Even when rainfall is absent moisture at this site is largely constant due to fog drip from clouds blowing over the ridge. Soil consists of mud on the slopes but with pockets of humus, especially along the ridge. The region is subject to major landslides, with a large landslide extending from just below the type locality to the bottom of an adjacent valley at approximately 250 m elevation. Animals were abundant at the type locality. They also occured less commonly in tall, lowland secondary forest growing at 280 m on clay mud and scree slides. In this area the undergrowth was not dense, and palms, pandanus, and ferns were common.

Frogs called from late afternoon through early morning at the type locality; calling perches were typically stems or leaves from 1-4 m above ground. Frogs typically emitted the longer advertisement calls when conditions were wet. In those circumstances they were not shy and were easily captured. Under drier conditions, the frogs gave slower calls at more erratic intervals, and they often called from hidden perches. Calls in the population would often move in a wave of chorusing activity across the mountain.

The smallest mature male was 16.3 mm SV, and it was recorded calling, but another male at 16.5 mm SV was not yet mature. The smallest mature female had a SV of 19.0 mm; two immature females were 17.0 and 17.4 mm long. Hence, males mature at a smaller size than do females.

The frog community on Rossel Island is rather depauperate; syntopic frogs include only Austrochaperina yelaensis , Barygenys exsul , Cophixalus cupricarenus , Cophixalus kethuk , an undescribed Copiula , Litoria eschata , Litoria louisiadensis , Mantophryne louisiadensis , Nyctimystes perimetri , and an undescribed Oreophryne .