A New Species of Hylophorbus (Anura: Microhylidae) from Papua New Guinea

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1 Current Herpetology 32(2): , August by The Herpetological Society of Japan doi /hsj A New Species of Hylophorbus (Anura: Microhylidae) from Papua New Guinea FRED KRAUS Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA Abstract: I describe a new frog of the microhylid genus Hylophorbus from the north-coast mountain ranges of Papua New Guinea that is unique in its small size, continuous black lateral band bordered below by a white line and then a field of whitish gray, and other morphometric and color-pattern features that distinguish it from its two most similar congeners, each also possessing a black lateral band. The new species is one of the two smallest species in the genus. It is currently known only from two of the easternmost north-coast mountain ranges, although it seems likely to occur in nearby mountain ranges to the west, a distributional pattern that is common among endemic amphibians from this region. Key words: Adelbert Mts.; East Sepik Province; Madang Province; Prince Alexander Range INTRODUCTION Hylophorbus is a genus of Papuan microhylids whose members are inhabitants of the leaf litter and are active on the forest floor at night, calling either from exposed positions or from under the top layer of fallen leaves. For many years only one wide-ranging species, H. rufescens, was recognized in this genus (Zweifel, 1972), but Günther (2001) has shown that Hylophorbus in fact contains a diversity of species. However, description of this diversity has been hindered by the fact that the type species, Hylophorbus rufescens, is poorly understood, being based on a brief description of a poorly preserved specimen from Katow, in the lowland forests of Western Province (Macleay, 1878). Collections of new material address: fkraus@umich.edu from the type locality are lacking. The resulting taxonomic ambiguity has made description of a diversity of recently discovered species (Richards, 2002; F. Kraus, unpublished data) impossible because of overall morphological resemblance to the poorly defined type species. Presently, nine species are recognized within Hylophorbus (Zweifel, 1972; Günther, 2001; Richards and Oliver, 2007; Kraus and Allison, 2009), most of which occur along the northern versant of the island. The total number of species in the genus is likely to reach two dozen or more once the systematics are properly worked out. Despite the taxonomic difficulties attending the type species, some Hylophorbus are easily distinguished from that species and from all other named taxa. During recent expeditions to two of the isolated coastal ranges along northern Papua New Guinea I obtained a new species of

2 KRAUS A NEW FROG FROM PAPUA NEW GUINEA 103 Hylophorbus that is among these, being readily distinguished from all congeners by its small size and distinctive color pattern. I take this opportunity to describe this new form here. MATERIALS AND METHODS I made all measurements with digital calipers or an optical micrometer to the nearest 0.1 mm, with the exception that disc widths were measured to the nearest 0.01 mm. Measurements, terminology, and abbreviations follow Zweifel (1985) and Kraus and Allison (2006a): body length from snout to vent (SV); tibia length from heel to outer surface of flexed knee (TL); horizontal diameter of eye (EY); distance from anterior corner of eye to center of naris (EN); internarial distance, between centers of external nares (IN); distance from anterior corner of eye to tip of snout (SN); head width at widest point, typically at the level of the tympana (HW); head length, from tip of snout to posterior margin of tympanum (HL); horizontal tympanum diameter (TY); hand length, from proximal edge of palm to tip of 3rd finger (HandL); foot length, from proximal edge of sole to tip of 4th toe (FootL); width of the third finger disc (3rdF); and width of the fourth toe disc (4thT). For the new species, I measured mass to the nearest 0.05 g on freshly euthanized animals using a 10g Pesola spring scale (Fresh mass). I also re-measured their mass once stored in ethanol for comparison to the mass of preserved specimens of their closest relatives (Preserved mass). Those measurements were taken after specimens had been blotted dry on paper towel. I determined sex of animals by dissection, maturity of males by presence of vocal slits, and maturity of females by presence of enlarged ova. I confirmed generic assignment of the frogs by their combination of having eleutherognathine maxillae; very long legs, fingers, and toes; well-developed subarticular tubercles; and small digital discs (Zweifel, 1972). For species diagnoses, I relied on direct comparison to museum material (Appendix I) as well as to information from Günther (2001) and Richards and Oliver (2007). Type specimens of the new species are deposited in the Bernice P. Bishop Museum, Honolulu (BPBM). Latitude and longitude coordinates for the type series use the World Geodetic System, 1984 (WGS 84). SYSTEMATICS Hylophorbus atrifasciatus sp. nov. Figs. 1A D, 2 Holotype BPBM (field tag FK 13708), adult male, collected by local villager 1 October 2009 at Mongan, S, E, 850 m asl., Adelbert Mts., Madang Province, Papua New Guinea. Paratypes Papua New Guinea: BPBM 34724, immature male, collected by F. Kraus from East Sepik Province: Prince Alexander Mts., Mindangua Stream, S, E, 360 m asl.; BPBM 34725, immature male, and BPBM 34727, immature female, collected by F. Kraus from Madang Province: Adelbert Mts., Keki Lodge, S, E, 850 m asl. Etymology The name is a masculine compound Latin adjective meaning having a black band and refers to the most immediately distinctive color-pattern feature of this species. Diagnosis A small-sized species of Hylophorbus (one adult male SV 22.8 mm, mass 1.2 g fresh, 1.2 g preserved) with relatively long legs (TL/SV ); long and broad snout (EN/SV ; IN/SV 0.11); large tympanum (TY/SV , TY/EY ); large finger discs (3rdF/4thT ); continuous black lateral band without isolated lumbar ocellus, not clearly distinct from dark-brown dorsum, margined below by narrow white line, below which is a gray-white lateral field (Fig. 1A C); dorsal surfaces of limbs same color as

3 104 Current Herpetol. 32(2) 2013 FIG. 1. Portraits in life of (A) Hylophorbus atrifasciatus sp. nov., holotype (BPBM 34726), (B) H. atrifasciatus, paratype (BPBM 34725), (C) H. atrifasciatus, paratype (BPBM 34724), (D) ventral view of H. atrifasciatus, paratype (BPBM 34724), (E) H. nigrinus, holotype (ZMB 62402), and (F) H. picoides, paratype (ZMB 74639). dorsum of body (Fig. 1A C); axilla, groin, abdomen, and ventral surfaces of legs yellow (Fig. 1D); brown flecks on ventral surfaces of thighs forming a reticulum (Fig. 1D). Description of holotype An adult male. Head wide (HW/SV=0.38), wider than long (HL/SV=0.35, HL/HW= 0.92), with almost vertical loreal region; upper lip slightly inflated; canthus rounded, slightly convex when viewed from above; nostril directed laterally, closer to tip of snout than to eye; internarial distance larger than distance from naris to eye (EN/IN=0.76, IN/SV= 0.11, EN/SV=0.083); snout shallowly rounded/ almost truncate when viewed from above (Fig. 2A), rounded when viewed from side (Fig. 2B); eye moderately large (EY/SV=0.11); eyelid somewhat smaller than interorbital distance; tympanum distinct and large (TY/SV=0.088, TY/EY=0.77), with raised annulus. Fingers unwebbed, bearing small discs with shallow terminal grooves on F2 F4, groove absent from F1; relative lengths 3>4>2>1 (Fig. 2C). Finger discs slightly wider than penultimate phalanges (3rdF/SV=0.028). Subarticular

4 KRAUS A NEW FROG FROM PAPUA NEW GUINEA 105 FIG. 2. (A) Dorsum, (B) lateral view, (C) palmar view of left hand, and (D) plantar view of left foot of holotype of Hylophorbus atrifasciatus sp. nov. (BPBM 34726). Scale bars=5 mm; small bar applies to (A) and (B), large bar to (C) and (D). tubercles well developed, rounded; inner and outer metacarpal tubercles well developed, oval, with large medial, oval metacarpal tubercle in between. Toes unwebbed, all bearing discs with terminal grooves; relative lengths 4>3>5>2>1 (Fig. 2D). Toe discs much larger than those of fingers (3rdF/ 4thT=0.55); disc of fourth toe twice width of penultimate phalanx; disc of first toe 1.5 times wider than penultimate phalanx. Subarticular tubercles well developed, rounded; inner metatarsal tubercle a large, prominent oval; outer lacking. Hind legs long (TL/SV=0.57). Vocal slits present on each side of tongue, relatively small. Dorsum and sides mostly covered with dense network of tiny, anastomozing wrinkles; thin raised vertebral ridge extending from tip of snout to urostyle. Ventral surfaces smooth. Dorsum dark brown, grading into a black lateral stripe extending continuously from behind eye to groin, this bordered below by a narrow white line, below which is a gray-white field evenly stippled with brown and with several scattered small brown blotches (Fig. 2A, B), this field lacking brown stippling in the groin. Top of head and face dark brown, vaguely mottled with gray on lip, no dark subocular blotch. Tops of limbs same color as dorsum of body; front and rear of thighs dark brown with irregular pale straw-brown blotches; a dark-brown blotch on wrist and dark-brown blotches on front and rear of arm. Pale-gray blotch above tip of urostyle, margined in black posterolaterally. Ventral ground color pale straw brown, heavily mottled with dark choco-

5 106 Current Herpetol. 32(2) 2013 late brown from chin to anterior half of abdomen; posterior abdomen largely clear pale straw brown; thighs ventrally same pale straw brown but with reticulum of dark-brown flecks. Shank and arm ventrally clear pale straw brown with dark brown encroaching from sides. Palmar and plantar surfaces dark brown. Iris silver heavily suffused with dark brown, dark brown in overall appearance. Measurements (in mm). SV=22.8, TL= 13.1, HW=8.7, HL=8.0, IN=2.5, EN=1.9, SN=2.9, EY=2.6, TY=2.0, HandL=5.7, FootL=12.2, 3rdF=0.64, 4thT=1.16, Fresh mass=1.20 g, Preserved mass=1.20 g. Variation The sample is too small to provide any reasonable assessment of mensural variation (Table 1). One specimen is a mature male with SV of 22.8 mm, and one other is immature TABLE 1. Mensural data for the type series of Hylophorbus atrifasciatus sp. nov. Character BPBM Immature male BPBM Immature male BPBM Adult male BPBM Immature female Fresh mass (g) SV (mm) TL (mm) EN (mm) IN (mm) SN (mm) TY (mm) EY (mm) HW (mm) HL (mm) HandL (mm) FootL (mm) rd F (mm) th T (mm) TL/SV EN/SV IN/SV SN/SV TY/SV EY/SV HW/SV HL/SV HandL/SV FootL/SV rdF/SV thT/SV EN/IN rd F/4th T HL/HW TY/EY

6 KRAUS A NEW FROG FROM PAPUA NEW GUINEA 107 with 18.8 mm SV. The sole female of 18.3 mm SV is also immature. Little variation is present in color pattern among preserved specimens. The lower surfaces of the faces of BPBM are slightly paler than in the holotype, contrasting more with the dark-brown canthal region or top of head. Each of the paratypes has somewhat more of the pale ventral ground color showing through on the chin and throat than does the holotype. There is no variation in the details of lateral and dorsal color-pattern elements that distinguish H. atrifasciatus from other members of the genus. In life, color of BPBM was noted as: Dark brown with black lateral stripe. Venter and sides tan-white with small brown spots. Chin, throat, and chest black. Under legs, groin and axilla pale yellow. Rear of thighs dark brown spotted with yellow. Iris dark brown. The white lateral line below the black lateral band was evident in all animals (Fig. 1A); and the pale yellow extended onto the posterior abdomen in BPBM (Fig. 1B). The field below this white line was pale brown in BPBM instead of gray-white, and the abdomen was lemon yellow. A small orange spot was also present at the junction of the hindlimb with the body in BPBM Call Unknown. Distribution Known from the Prince Alexander Range, East Sepik Province, and Adelbert Mts., Madang Province, Papua New Guinea (Fig. 3). Ecological notes This species occurred in primary lowland and lower montane rainforest ranging from m elevation. The site in the Prince FIG. 3. Map of northern New Guinea showing type locality for Hylophorbus atrifasciatus sp. nov. (filled circle) in Adelbert Mts., Madang Province, and additional locality in Prince Alexander Range, East Sepik Province (open circle), Papua New Guinea.

7 108 Current Herpetol. 32(2) 2013 Alexander Range was moderately open primary foothill rainforest on a steep slope. Understory was fairly well developed and contained many rattan palms (Calamus); canopy was approximately 35 m, with emergents to 50 m. The forest around Keki Lodge, Adelbert Mts., was a ca. 10 ha remnant of primary foothills rainforest surrounded by secondary forest in all directions. Forest there was fairly open. Frogs at both sites were found active at night on the leaf litter along ridgetops but appeared uncommon, judging by absence of calling frogs and the rarity with which I observed this species relative to other frogs found at the two sites. Syntopic frogs include Albericus gudrunae, Austrochaperina basipalmata, an undescribed species of Austrochaperina, Callulops microtis, Choerophryne proboscidea, Cophixalus balbus, C. cheesmanae, C. pipilans, Copiula fistulans, C. tyleri, Hylarana garritor, H. papua, H. volkerjane, Hylophorbus proekes, two undescribed species of Hylophorbus, Liophryne schlaginhaufeni, Litoria arfakiana, L. gasconi, L. genimaculata, an undescribed species of Litoria, Mantophryne lateralis, Oreophryne biroi, O. parkeri, Platymantis papuensis, and Sphenophryne cornuta. Comparisons Hylophorbus atrifasciatus is immediately distinguished from all other members of the genus except H. picoides and H. nigrinus by its black lateral band on each side bordered below by a narrow white line below which is a pale-gray lower-lateral region. It is distinguished from H. picoides by its smaller size; relatively larger snout; larger tympanum; somewhat larger finger discs; absence of a black lumbar ocellus; black lateral band poorly TABLE 2. Diagnostic differences between Hylophorbus atrifasciatus, sp. nov., and its two most similar relatives, H. picoides and H. nigrinus. Character H. atrifasciatus H. picoides H. nigrinus Preserved mass (g) SV of adult male (mm) TL/SV EN/SV IN/SV TY/SV TY/EY rdF/4thT Black lumbar ocellus absent present absent Color of lateral band Lateral band Poorly differentiated from dorsal color field Of even width throughout, continuing in straight line from eye to groin Clearly distinct from dorsal color field Narrowed behind eye, dipping ventrally and ending at midbody Poorly differentiated from dorsal color field Of even width throughout, continuing in straight line from eye to groin Brown flecks under thighs Forming a reticulum Discete, scattered Forming a reticulum Color of lower lateral field Gray-white Gray-white Yellowish or brownish White blotches in groin Absent Absent Present White V in coccygeal Absent Absent Present region Pale dash behind eye Absent Absent Present Tops of limbs Same color as dorsum Same color as dorsum Distinctly paler than dorsum

8 KRAUS A NEW FROG FROM PAPUA NEW GUINEA 109 differentiated from the dark dorsal color, of even width throughout and continuing in a straight line from behind eye to groin; and brown flecks under thighs forming a reticulum (Table 2, Fig. 1A C vs. Fig. 1F). From H. nigrinus, the new species is distinguished by its smaller size; relatively larger tympanum; longer leg; somewhat larger finger discs; graywhite lateral field; no white (orange in life) blotches in groin or white (orange in life) V margin along the coccygeal region; absence of a pale, curved dash behind eye; and tops of limbs same color as dorsum (Table 2, Fig. 1A C vs. Fig. 1E). Only Hylophorbus richardsi is similar to H. atrifasciatus in body size, but it lacks black lateral bands and pale-gray lowerlateral field. DISCUSSION Because of the confusion attending the exact taxonomic identity of Hylophorbus rufescens, the type species for the genus, a diversity of new Hylophorbus species with similar blotched dorsal patterns remain collected but undescribed (Richards, 2002). This is not a problem for the new species described herein because its black lateral band clearly separates it from H. rufescens and all other nomina currently placed in synonymy or subspecific standing with that species. The closest known relative to Hylophorbus atrifasciatus would appear to be H. picoides, currently known only from the Wondiwoi Peninsula 1000 km to the west of the westernmost locality of H. atrifasciatus. Along with the less similar H. nigrinus, H. picoides is the only other Hylophorbus species that exhibits the distinctive (and presumably synapomorphic) black lateral band. It will be interesting to determine whether other black-banded Hylophorbus species occupy the intervening areas of New Guinea s northern coast, a circumstance that seems likely. Although there are a few striking instances of frog species endemic to the northern ranges of New Guinea occurring across the entire extent of that area (e.g., Cophixalus balbus, Hylarana volkerjane: Kraus and Allison, 2006b), most of those endemics are instead found in only a few of those mountain ranges, and none of the several species described from the easternmost ranges in Papua New Guinea has yet to be discovered in the western bird s neck region where H. picoides resides. This is unsurprising because that region comprises the Vogelkop Composite Terrane, which was sutured to New Guinea from the northwest approximately 12 million years ago (MY) (Pigram and Symonds, 1991; Polhemus and Polhemus, 1998). In contrast, the remaining north-coast ranges comprise portions of the Northern Island-Arc Terranes (Pigram and Symonds, 1991), a series of former island arcs obliquely sutured onto the northern margin of New Guinea from west to east over the past 20 MY (Davies et al., 1997). Given these different geological derivations, one would expect relatively few frog species to have the mobility to establish themselves over that entire extent of habitat, and few appear to have done so. However, most of the northern versant of Papua Province of Indonesia, which includes the western series of north-coast ranges, has been very poorly collected; hence, it remains unknown to what extent the many species endemic to one or more of the north-coast ranges in Papua New Guinea, to the east, also occur in these western ranges, or whether they are replaced by cognate species endemic to those mountains. In at least a few cases, species recently described from one of these ranges (Foja Mts., also part of the Northern Island-Arc Terranes system) also occur to the east in Papua New Guinea (Kraus and Allison, 2006b; Kraus, in press), further emphasizing that much of the frog fauna endemic to the Northern Island-Arc Terranes region is widespread within it. Further collecting in the western portion of this region should clarify whether the geological break between the Vogelkop Composite Terrane and Northern Island-Arc Terranes has left its signature in two adjacent herpetofaunas that are sharply distinct on either side of that junction. Currently, few of the species

9 110 Current Herpetol. 32(2) 2013 described from the Vogelkop Composite Terrane seem to range widely east of that area. ACKNOWLEDGEMENTS I thank D. Frost and D. Kizirian (AMNH), R. Sadlier (AMS), M. Hagemann (BPBM), R. Günther and M.-O. Rödel (ZMB), J. Rosado (MCZ), and M. Hoogmoed (RMNH) for loans of specimens; R. Günther for kindly providing me with photographs of Hylophorbus nigrinus and H. picoides; I. Haguna, J. Jiramori, A. Nakung, M. Nakung, M. Okira, C. Wintawa, and D. Yaripona for field assistance; M. Okira and B. Yawi for logistical assistance and permission to work on their land; S. Myers for producing Fig. 2; P. Imada for specimen curation; the PNG National Museum and Art Gallery for providing in-country collaborative assistance; and the PNG Department of Environment and Conservation, PNG National Research Institute, and Oro Provincial Government for permission to conduct this work. This research was supported by National Science Foundation grant DEB LITERATURE CITED DAVIES, H. L., PEREMBO, R. C. B., WINN, R. D., AND KENGEMAR, P Terranes of the New Guinea Orogen. p In: G. Hancock (ed.) Proceedings of the Geology Exploration and Mining Conference, Madang. Australasian Institute of Mining and Metallurgy, Melbourne. GÜNTHER, R The Papuan frog genus Hylophorbus (Anura: Microhylidae) is not monospecific: description of six new species. Russian Journal of Herpetology 8: KRAUS, F. In press. Further range extensions for reptiles and amphibians from Papua New Guinea. Herpetological Review. KRAUS, F. AND ALLISON, A. 2006a. Three new species of Cophixalus (Anura: Microhylidae) from southeastern New Guinea. Herpetologica 62: KRAUS, F. AND ALLISON, A. 2006b. Range extensions for reptiles and amphibians along the northern versant of Papua New Guinea. Herpetological Review 37: KRAUS, F. AND ALLISON, A New species of frogs from Papua New Guinea. Bishop Museum Occasional Papers 104: MACLEAY, W The batrachians of the Chevert expedition. Proceedings of the Linnean Society of New South Wales 2: PIGRAM, C. J. AND SYMONDS, P. A A review of the timing of the major tectonic events in the New Guinea Orogen. Journal of Southeast Asian Earth Sciences 6: POLHEMUS, D. A. AND POLHEMUS, J. T Assembling New Guinea: 40 million years of island arc acretion as indicated by the distributions of aquatic Heteroptera (Insecta). p In: R. Hall and J. D. Holloway (eds.) Biogeography and geological evolution of Southeast Asia. Backhuys Publishers, Amsterdam. RICHARDS, S. J Rokrok: an illustrated guide to the frogs of the Kikori River Basin. World Wildlife Fund, Papua New Guinea. RICHARDS, S. J. AND OLIVER, P. M A new species of Hylophorbus (Anura, Microhylidae) from the Huon Peninsula, Papua New Guinea. Mitteilungen aus dem Museum für Naturkunde in Berlin, Zoologische Reihe 83 supplement: ZWEIFEL, R. G A revision of the frogs of the subfamily Asterophryinae family Microhylidae. Bulletin of the American Museum of Natural History 148: ZWEIFEL, R. G Australian frogs of the family Microhylidae. Bulletin of the American Museum of Natural History 182: APPENDIX 1 Specimens Examined Collection abbreviations are AMS (Australian Museum, Sydney), AMNH (American Museum of Natural History, New York), BPBM (Bernice P. Bishop Museum, Honolulu), MCZ (Museum of Comparative Zoology, Cambridge, Massachusetts), PNGNM (Papua New Guinea National Museum, Port Moresby), RMNH (Naturalis-Nationaal Natuurhistorisch Museum, Leiden), and ZMB (Museum für Naturkunde, Berlin).

10 KRAUS A NEW FROG FROM PAPUA NEW GUINEA 111 Hylophorbus nigrinus (n=2): Indonesia: West Papua Province: 7 km N Konti, Yapen Island (ZMB , paratypes). Hylophorbus picoides (n=3): Indonesia: West Papua Province: 8 km W Yeretuar, Wondiwoi Mts. (ZMB , paratypes). Hylophorbus proekes (n=25): Papua New Guinea: West Sepik Province: SSE slope Mt. Sapau, Torricelli Mts. (BPBM , PNGNM , type series). Hylophorbus richardsi (n=14): Papua New Guinea: Southern Highlands Province: E slope Mt. Itukua, Muller Range (BPBM ). Hylophorbus rufescens (n=19): Indonesia: Papua Province: the Moso and Tami rivers, east of Jayapura (RMNH 4631, holotype of Metopostira macra); Papua New Guinea: Milne Bay Province: Sudest Island (AMNH 60085, , , , paratypes of H. r. extimus), Woodlark Island (AMNH 59982, 59985, 59987, , , paratypes of H. r. myopicus); Western Province: Kuru (MCZ ), Boze (MCZ 82629), Emeti (AMNH 90399, MCZ 82757), Katow (AMS 30826, holotype of H. rufescens). Hylophorbus tetraphonus (n=3): Indonesia: West Papua Province: 8 km W Yeretuar, Wondiwoi Mts. (ZMB , paratypes). Hylophorbus wondiwoi (n=3): Indonesia: West Papua Province: 10 km W Yeretuar, Wondiwoi Mts. (ZMB , paratypes). Accepted: 2 April 2013