Cornufer macrosceles (Zweifel 1975)

Platymantis macrosceles was originally described by Zweifel (1975), based on a single female specimen. It has since been redescribed along with two other specimens (Foufopoulos and Brown 2004). Platymantis macrosceles can be distinguished from other geographically proximate congeners by its bright yellowish-green to olive-green ground coloration with symmetric brown patches on the dorsum. The tip of the snout is slender and acutely pointed. There is a large tubercle on the snout tip. and another tubercle slightly anterior and medial to each nostril. Each eyelid also bears one or two prominent yellow tubercles, with one large tubercle located medially on the eyelid and sometimes a smaller one immediately posterior to it. White-tipped, enlarged tubercles are also present along the outer edge of the tarsi, particularly at the tibio-tarsal articulations. Pale yellow to bright white tubercles are present at the margin of the jaw. The skin is smooth but has low, white conical tubercles on the dorsum. There are also a pair of enlarged white tubercles on each side of the vent (Foufopoulos and Brown 2004). The canthus rostralis is nearly straight over much of its length but curves abruptly anterior to the eye. The loreal region is deeply concave and nearly vertical. The snout is elongated and pointed. The pupil is horizontally elliptical. The tympanum is vertically oval and distinct but small. Vomerine teeth are in two groups medial and posterior to the internal nares. Relative finger lengths are as follows: 3>4>2>1. Relative lengths of the toes are 4>3>5>2>1. Toe discs are widely expanded but smaller than those on the fingers. Discs of the first and fifth toes are about one and one-half times the width of the penultimate phalanges. There is no webbing (Zweifel 1975; Foufopoulos and Brown 2004). The dorsal body surfaces are bright yellowish-green to olive-green, with the head, central dorsal region of the body, and sacral region being the darkest green and the lateral portions of the head and limbs being the lightest yellow. Symmetric chestnut-brown patches are present on the dorsum, flanks, and tibia. The post-axial regions and humerus are bright yellow. There is a single dark supra-axillary spot, as well as clusters of darker melanic spots on the sacrum. The nares are darker and a faint canthal stripe runs from the eye to the naris. The labial region and scapular crests are bright yellow. Above the pupil, the iris is bright golden yellow; below the pupil, the iris is grayish-yellow. Hands and feet are dark green with pale yellow discs on the digit tips (Foufopoulos and Brown 2004). Other members of this genus that also have large digital discs and are sympatric with Platymantis macrosceles are P. guppyi, P. neckeri, and P. nexipus. However, P. macrosceles can be distinguished from these species based on the following combination of characters: bright green and brown mottled dorsal coloration; small adult SVL (30 mm), prominent tubercles on eyelids and the tarsal segments of the hind limbs, long hind limbs (TL/SV, 0.589), unwebbed toes, internarial distance much less than distance from eye to naris (E-N/IN, 1.68), and a narrow head (HW/SV, 0.321) (Zweifel 1975; Foufopoulos and Brown 2004).

The exact type locality is unclear. The holotype was collected by E. J. Ford, Jr. at a locality recorded as Ti, Nakanai Mountains, West New Britain Province, Papua New Guinea, on July 29, 1956. However, this locality does not appear on maps, and the Nakanai Mountains are actually in central New Britain province. The elevation was apparently not recorded (Zweifel 1975). Subsequently two more specimens were collected in the Nakanai Mountains, on the ridge between the Ivule and Sigole Rivers, at 900 m above sea level (Foufopoulos and Brown 2004). They were perched on mossy branches above a mountain stream on a steep slope.

This frog perches on mossy branches of shrub-layer vegetation near small montane streams, about 1 m above the ground. The coloration and skin texture are cryptic and mimic the mossy substrate (Foufopoulos and Brown 2004). The advertisement call is highly pulsed and amplitude-modulated, and has been described as a "krrrr...krrrr..." which sounds like a "moderately rapid vibration of wood on wood". Calls vary from short chirps with 2-4 pulses, to a long series of 15-20 pulses. Longer calls begin with an initially rapid burst of pulses, after which both pulse duration and interpulse interval steadily increase. During the first three pulses, the frequency climbs from 2.07 to 2.24 to 2.5-2.66 kHz, with dominant frequencies then remaining at 2.5-2.66 kHz. Two faint harmonics are present at 4.65 and 6.99 kHz (Foufopoulos and Brown 2004). Platymantis macrosceles is rare but quite cryptic, and it is suspected that this species might be present in other New Britain, Papua New Guinea localities with similar habitat (Foufopoulos and Brown 2004).

Cornufer macrosceles is a species of frog in the family Ceratobatrachidae. It is endemic to the island of New Britain, Papua New Guinea. It is only known from the Nakanai Mountains in the central part of the island. Only three specimens are known. Common name Ti wrinkled ground frog has been coined for the species.