New genus of diminutive microhylid frogs from Papua New Guinea

Abstract

A new genus of diminutive (10.1-11.3 mm) microhylid frogs is described from New Guinea that is unique in its combination of having only seven presacral vertebrae, a reduced phalangeal formula that leaves the fi rst fi ngers and fi rst toes as vestigial nubs, and reduction of the prepollex and prehallux to single elements. Relationships to other genera are unknown, but overall similarity suggests some relationship to Cophixalus, although that genus also diff ers in some muscle characters and likely remains paraphyletic. Th e new genus contains two species, which are among the smallest known frogs in the world. Th eir miniaturization may be related to their inhabiting leaf litter, exploitation of which may select for small size. Th e new genus is currently known only from one mountaintop in the southeasternmost portion of New Guinea and another on a nearby island. Th is region is part of the East Papuan Composite Terrane and, should this lineage prove endemic to that region, it may suggest that it originated prior to that geological unit's docking with mainland New Guinea at 23-29 MY.

Description of a striking new Mantophryne species (Amphibia, Anura, Microhylidae) from Woodlark Island, Papua New Guinea

“…The new species is assigned to the genus Mantophryne on the basis of the following characters: body slender, circum-marginal grooves on all finger and toe discs, those on the toes wider than those of fingers; symphygnathine condition of the maxillary bones (anterior processes of the maxillary bones not fused but almost in contact and joined by a ligament); and two protuberances on chin. It differs from all hitherto known congeners by its 1) relatively long legs (TL/SUL 0.55-0.57 vs. <0.51 in males of all congeners; Menzies 2006, Kraus andAllison 2009), 2) more expanded terminal discs on the toes, 3) smooth dorsum, 4) advertisement calls consisting of 38-52 notes and lasting 4.6-6.5 s, and 5) distinct colouration normally comprising a uniformly golden tan dorsum, broad blackish dorsolateral bands edged below with a narrow, slightly undulating white stripe and large, distinct dark brown blotches each encircled by a white border, on the abdomen.…”

“…With a snout-vent length up to 82 mm Mantophryne louisiadensis is substantially larger than the new species; it also has a broader head, a more robust habitus, lacks dark lateral bands and does not exhibit the striking golden tan middorsal area or clearly delimited brown spots on the abdomen (Zweifel 1972, Kraus andAllison 2009).…”

“…Moreover, its advertisement call contains 13-18 notes (vs. 38-52 notes) with a mean note duration of 126 ms (vs. about 50 ms) and a mean note repetition rate of 1.8 notes/s (vs. 8.1 notes/s) at 26.5 °C (Kraus and Allison 2009).…”

“…Our information concerning features of Mantophryne species was taken from original descriptions (Boulenger 1897;Parker 1934;Zweifel 1972;Kraus and Allison 2009), recompiled treatises (Parker 1934;Zweifel 1972;Burton 1986, Menzies 2006Oliver et al 2013) and our own observations including direct examination of eight Mantophryne lateralis (SAMA R69327-34) specimens from mainland New Guinea.…”

“…On the basis of osteological and myological studies Burton (1986) then resurrected the name Mantophryne where he accommodated the symphygnathine species infulata, lateralis and louisiadensis. These three species were later complemented by M. axanthogaster Kraus & Allison, 2009. In a recent paper Oliver et al (2013) studied phylogenetic relationships between the closely related genera Mantophryne, Hylophorbus and Pherohapsis Zweifel, 1972. They used three mitochondrial and three nuclear genes and confirmed M. lateralis, M. louisiadensis and M. axanthogaster as congeneric; the monotypic Pherohapsis menziesi Zweifel, 1972 is also nested within Mantophryne and was transferred to that genus; M. infulata is nested within Hylophorbus and was included in that genus as H. infulatus.…”