A new and minute species of Austrochaperina (Amphibia: Anura: Microhylidae) from western New Guinea

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Introduction
In a recent revision ZWEIFEL (2000) split the Australopapuan microhylid genus Sphenophryne sensu PARKER (1934) into four genera, for all of which names were already available, namely Austrochaperina FRY, 1912 including 24 species at present; Liophryne BOULENGER, 1897 with six species; Oxydactyla VAN KAMPEN, 1913 with fi ve species; and Sphenophryne PETERS & DORIA, 1878 with one species. The genus Austrochaperina was diagnosed by ZWEIFEL (2000) as follows "A genus of genyophrynine microhylid frogs (sensu ZWEIFEL, 1971;BURTON, 1986) with the following combination of morphological characters: clavicles long and slender, reaching from scapula almost to midline of pectoral girdle; tips of fi ngers and toes (except sometimes the 1st) fl attened and disclike with terminal grooves and typically broader than penultimate phalanx, the disc of the 3rd fi nger narrower or no broader than that on the 4th toe; subarticular elevations low and rounded, almost undetectable in some species". According to ZWEIFEL (2000) snout-vent lengths of the adults range from 20 to 50 mm. Most species are surface dwell-ers on and below leaf-litter, and some inhabit riparian habitats along small streams. The genus is distributed from sea level to elevations of approximately 2000 m above sea level (a.s.l.). Most species occur on the main island of New Guinea, some on adjacent islands, and fi ve in northern Australia.
During fi eld work in the Wondiwoi Mountains at the base of the Wandammen Peninsula, Papua Province, Indonesian New Guinea, in various years between 1998 and 2003 the present author together with indigenous helpers found, among others, a tiny species of Austrochaperina which could not be allocated to any of the hitherto recognized taxa. This new species is described in the following text.

A new and minute species of Austrochaperina (Amphibia: Anura: Microhylidae) from western New Guinea
Most frogs of the new species were collected at night after locating them by their advertisement calls. One female was found serendipitously. Frogs were anaesthetized with chlorobutanol and most were stored in 2% formalin in the fi eld and transferred to 75% ethanol in the collection of the ZMB. Clearing and double staining of one specimen as an osteological preparation was carried out according to a modifi ed method of DINGERKUS & UHLER (1977).
Measurements of SUL and TL to the nearest 0.1 mm were made with a digital caliper, all others with an ocular micrometer in a dissecting microscope:

SUL
snout-urostyle length, from tip of snout to distal tip of urostyle bone (SUL and snout-vent length differ insignifi cantly, but SUL is more accurately measured) TL tibia length, external distance between knee and heel (caliper gently pressed) F3D transverse diameter of third fi nger disc T4D transverse diameter of fourth toe disc HL head length, from tip of snout to posterior margin of tympanum HW head width, taken in the region of the tympana END distance from anterior corner of orbital opening to centre of naris IND internarial distance between centres of nares ED eye diameter, from anterior to posterior corner of orbital opening TyD horizontal diameter of tympanum All calls were recorded in the fi eld with a Sony Digital Audio Tape (DAT) Walkman TCD-D 100 and a Sennheiser microphone MKE 300 and analysed with Avisoft-SAS Lab software. Specimens are currently housed in the herpetological collection of the Museum für Naturkunde, Berlin (ZMB) and bear registration numbers of this institution. Part of the types will be transferred to the Museum Zoologicum Bogoriense (MZB) at Cibinong (Indonesia). Diagnosis. Four adult males measured from 15.0 to 15.8 mm SUL and one adult female 16.6 mm. With this body size, Austrochaperina minutissima is the smallest known species of this genus. Only A. polysticta with but one known and now destroyed specimen of 16.5 mm SVL is probably of a similar small size. From an illustration of the whole body by MÉHELY (1901),

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Vertebrate Zoology ■ 59 (1) 2009 it can be calculated that A. polysticta exhibits a TL/ SVL ratio of 0.44. With a TL/SUL-ratio of 0.46-0.49 the new species has somewhat longer hind legs than does A. polysticta. Moreover, A. polysticta exhibits a dark red-brown stripe from the tip of the snout, passing along the upper eyelid and the upper margin of the tympanum, and extending to the midbody region; such a stripe is missing in A. minutissima. The advertisement calls of A. minutissima consist of short trains of high-pitched peeps with a mean call length of 0.94 s, a mean number of notes per call of 10, a mean note length of 43 ms, and a mean note repetition rate of 10.8 per s.
Description of the holotype. An adult male with a snout-urostyle length of 15.6 mm. For measurements and body-ratios see Table 1. Head in the region of the tympana as wide as the remaining body. Snout rounded, in profi le protruding (Fig. 1a). Nostrils laterally directed and closer to snout tip than to eyes, distance between nares distinctly greater than distance between eye and naris ( Fig. 1b). Canthus rostralis straight and gently rounded. Tongue small, elongate, half free posteriorly, and without a posterior indentation. Prepharyngeal ridges scarcely visible. Elongate vocal slit on each side of the tongue. Tympanum clearly expressed, its horizontal diameter slightly more than half eye diameter, no supratympanic skin fold. Eye of middle size (ED/SUL 0.115), with horizontal pupil. Fore limbs short with small hands and short fi ngers, their tips not (fi ngers 1 and 2) or only scarcely (fi ngers 3 and 4) broader than penultimate phalanges (Fig. 2a); terminal grooves present on fi ngers but weakly expressed; some rugosity on palmar surface, no subarticular tubercles; relative length of fi ngers 3 > 4 > 2 > 1. Hind limbs much stronger developed than fore limbs. Discs of toes 2, 3, and 4 clearly broader than penultimate phalanges, that of toe 5 about the same width as penultimate phalanx, all with terminal grooves; toe 1 rudimentary with no clear disc and no clear terminal groove. Metatarsal tubercles and subarticular tubercles absent. Relative length of toes 4>3>5>2>1, no webbing (Fig. 2b). All dorsal and ventral surfaces smooth.     Snout tip with a transparent whitish cap. Dorsal surface of head, body, and extremities reddish-brown with numerous dark brown spots. Dorsal surface of fore limbs as well as sides of body and head with some whitish fl ecks. Basic colour of all ventral surfaces light yellowish; throat, chest, inferior fl anks, and hind limbs more or less densely speckled with brown. Tympanum light brown and, in terms of colour, clearly demarcated from its surroundings. Loreal region and upper eyelids with large dark brown fl ecks. The colouration in life was largely the same, but was more intense and with numerous very small whitish fl ecks and streaks on all dorsal surfaces (Fig. 3).
Morphological variation in the type series. The type series consists of four adult males and one adult female for which measurements and body ratios are listed in Table 1. Sex was determined by inspection of gonads and of secondary sex characters (presence of vocal slits). There are only minor differences in SUL: males measure 15.0-15.8 mm and the female 16.6 mm. Due to the small sample size it is impossible to decide whether there are real differences in body size between the sexes. The female differs slightly in various body ratios from the males (Table 1) but, as with SUL, there are too few animals for conclusions in this respect. Basic colouration is much the same in all types. There are differences in the extent of spotting of the dorsal and ventral surfaces (Figs. 4a and 4b).
Osteological characteristics (based on a bone and cartilage preparation of ZMB 62574). Long and slender clavicles, reaching from scapula almost to midline of pectoral girdle, and an eleutherognathine condition  (2000). Frontoparietals as long as broad, not fused to one another but fused to exoccipital (Fig. 5a). Prootic separated from frontoparietal and exoccipital by broad and scarcely ossifi ed sutures. Occipital condyles prominent. Nasals sparsely mineralized, sphenethmoid largely covered by frontoparietals. Squamosal with distinct zygomatic ramus; otic ramus fairly short, broader than zygomatic ramus, and overlapping the cartilaginous crista parotica, basal part of ventral ramus greatly expanded (unusual at least in Australopapuan microhylids) and connected with quadratojugal and articulating with dentary. Palatine process of premaxillary relatively long and acuminate. Prevomer and palatine united. There is a bony element with a longitudinal split on the anterior mouth roof whose origin is dif-fi cult to interpret (Fig. 5b). Hyoid apparatus (Fig. 5c) with broad anterolateral and acuminate posterolateral processes; posteromedial processes with dilations; a transverse chasm in the central plate posterior of the posterolateral processes; central cartilaginous plate partly ossifi ed (unstippled areas). Ventral elements of pectoral girdle (Fig. 5d) are: long and slender clavicles that reach from nearly the midline of the girdle to the scapulae, their basal end strongly dilated; slender cartilaginous procoracoids expanded from epicoracoid cartilage up to scapulae; robust and angular-arranged coracoids, their distal ends narrower than their proximal ends; long and partly ossifi ed sternum with anchorshaped xiphisternum. Vertebral column (Fig. 5e) with eight procoelous, non-imbricate presacral vertebrae, sacral vertebra with expanded transverse processes, urostyle bone and ilia without crests. Radius and ulna  fused, no distal carpals, phalangeal formula of hand 3-3-4-4, ultimate phalanx of digit 1 tiny, that of digit 2 clearly expressed, neither T-shaped; ultimate phalanx of digits 2 and 4 T-shaped but transverse element very narrow. Phalangeal formula of foot 2-3-4-5-4 (there is a tiny terminal element on digit 1 that is too small to be considered as a phalanx); digits 2-5 each with Tshaped ultimate phalanx, transverse element of T in all cases small.

Distribution.
Wondiwoi Mountains at the base of the Wandammen Peninsula, border between Manokwari District and Nabire District, western Cenderawasih Bay, Papua Province, Indonesian New Guinea.
Habitat and ecology. All males were found on the main ridge of the mountain chain at approximately 900 m a.s.l. in primary mossy rain forest (Fig. 6). They were common. The female was accidentally found at 700 m a.s.l. All specimens were hidden under leaflitter. Males started to call in the late afternoon or at dusk, and call intensity decreased soon after nightfall; a few call series were heard up to midnight.
Vocalization. Advertisement calls consisted of a series of short and high pitched notes and strongly resembled the songs of crickets. Calls were uttered mostly in long series of up to several minutes in length, whereby length of calls as well as length of intercall intervals varied insignifi cantly (Fig. 7). The shortest interval between two consecutive calls was approximately 2 s. Mean call duration of 25 calls from three males was 0.94 s, SD 0.18, range 0.58-1.20 s. Number of notes in these calls: mean 10.0, SD 1.33, range 7-12. Mean length of 224 notes was 43 ms, SD 4.7, range 30-50 ms. Mean length of 199 internote intervals was 56 ms, SD 4.2, range 72-199 ms. Mean note repetition rate in 25 calls was 10.8 notes per s, SD 0.82, range 10.0-12.3 notes per s. Notes are unpulsed, their sound volume oscillates more or less. There are notes which start with the maximum sound intensity, in other notes the maximum sound intensity was at the end, and still others showed a bimodal sound intensity (Fig. 8,  above). There is a clear frequency modulation in all notes, and the frequency rises from approximately 5.5 kHz to about 6.5 kHz in the course of the note. Most notes exhibit three frequency bands: a fundamental frequency band reaching from 3 to 4 kHz, a dominant frequency band reaching from 6 to 7.5 kHz, and an upper harmonic band centering at 9.5 kHz. Most energy is concentrated in the dominant band, followed by the fundamental band, and the least energy is expressed in the upper harmonic band (Fig. 8, below, and Fig. 9). All calls were recorded at air temperatures of from 19 to 20 °C.

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Vertebrate Zoology ■ 59 (1) 2009 differences are in the structure of the anterior mouth roof: there is a bony element of unclear origin with a deep median longitudinal furrow in A. minutissima (Fig. 5b), the comparable element in A. mehelyi has an anchor-like shape (Fig. 5 in Table 6 in MÉHELY, 1901). A. novaebritanniae is slightly larger (males up to 19 mm SVL and females up to 21.9 mm SVL) than A. minutissima and is endemic to the island of New Britain (ZWEIFEL, 2000). Two specimens measured by me (MCZ A-73085-86) have distinctly shorter tibiae (TL/SUL 0.41 and 0.43) than A. minutissima (mean ratio TL/SUL 0.48). There are differences between these taxa also in body ratios TaL/SUL, T4D/SUL, T4D/F3D, HL/SUL, HL/HW, and TyD/ED.
The holotype and sole specimen of A. polysticta has been destroyed and no other specimens of that species are known. The holotype had a SVL of 16.5 mm and besides its verbal description by MÉHELY (1901) under the name Chaperina polysticta, there is also a colour illustration of its dorsal perspective and a drawing of the ventral elements of its pectoral girdle (MÉHELY, 1901). A. polysticta has shorter tibiae (TL/SUL 0.44) than A. minutissima (TL/SUL 0.46-0.49, mean 0.48) and a smaller tympanum (TyD/ED 0.40) than A. minutissima (TyD/ED 0.53-0.60). A. polysticta has a conspicuous dark brown stripe which begins at the posterior corner of the eye, touches the tympanum on its upper edge, and extends about to the middle of the body; no such stripe is present in A. minutissima. The smallest, tiniest, or extremely small or tiny. The suggested common name is Pygmy Land Frog.
Comparison with other species. Of fi ve specimens in the type series, the largest is a female of 16.6 mm SUL. There are only fi ve other Austrochaperina species with a similar size: A. gracilipes, A. mehelyi, A. novaebritanniae, A. polysticta, and A. adelphe. A. gracilipes is larger (males up to 20 mm and females up to 23 mm SVL) than A. minutissima, and according to ZWEIFEL (2000) inhabits grassy woodlands along small streams in low elevations, and has different calls. Its call notes last 0.14-0.15 s, that of A. minutissima 0.03-0.05 s; number of notes per second 1.3-1.7 in A. gracilipes and 10-12 notes per second in A. minutissima; and dominant frequency is approximately 4000 Hz in A. gracilipes and 6000 Hz in A. minutissima. Call parameters of the former species are from ZWEIFEL (2000).
According to ZWEIFEL (2000) A. mehelyi reaches snout-vent lengths of about 21 mm. Méhely mentioned a specimen with a 24.5 mm length. Thus, A. mehelyi can become considerably larger than A. minutissima. Specimen MCZ A-28406 of A. mehelyi, measured by me, shows the following differences from A. minutissima: TL/SUL in the latter is 0.46-0.49, in A. mehelyi 0.43; T4D/SUL in A. minutissima 0.040-0.051, in A. mehelyi 0.027; T4D/F3D in A. minutissima 2.13-3.0 (mean 2.67), in A. mehelyi 2.00; END/IND in A. minutissima 0.57-0.65, in A. mehelyi 0.52. Further latter exhibits many small whitish fl ecks on all dorsal surfaces, lacking in A. polysticta. There is one more obvious difference between these two taxa: the base of the clavicle is strikingly expanded in A. minutissima but only scarcely expanded in A. polysticta.
A. adelphe is known only from northern Australia. It is larger than A. minutissima, has different body ratios, lives in other habitats and has clearly different calls (ZWEIFEL, 2000).