Description
Platymantis diesmosi is a moderately sized frog with body size ranging from 28.3 to 39.1mm SVL for males and 49.8 to 52.7mm for females. Snout tip appears bluntly pointed in dorsal view and extends very slightly over the lower jaw. Lips are swollen and flared, extending to lateral edge of orbits. Eye diameter is wider than interorbital length and pupil is horizontally elliptical. Canthus rostralis is straight; loreal region is concave; nostrils are laterally protuberant, and the internarial region is convex. The tympanic annulus is distinct with the dorsal margin partly covered by a supratympanic fold. The tongue is long, subtriangular, and has deep posterior notch and short anterior attachment. Choanae are partially hidden behind the palatal shelf of maxillae. Examination of oval cavity shows a distinct vomerine process with six teeth (Brown and Gonzalez 2007).

Forearms appear slender and muscles do not exhibit hypertrophy. Digits of hands are long; terminal discs are slightly expanded with crescent-shaped folds; and webbing is absent. Fingers decrease in length from III>IV>I=II, and subarticular tubercles are noticeable with convex orientation towards ventrum. Thenar (inner metacarpal) tubercle is huge, long, and oval, with a raised, sharp ventromedial edge; palmar (outer metacarpal) tubercle is rounded and nearly bifid. There is no indication of the presence of nuptial pads (Brown and Gonzalez 2007).

Tarsus is smooth and shows absence of folds, flaps, and tubercles. Toes have slightly expanded discs with circummarginal grooves and supra-articular cutaneous flaps. Toe length decreases in size from IV=III>V>II>I. Inner metatarsal tubercle shows sharp plantar edge, and outer metatarsal tubercle appears small, round, and pointed. Toes exhibit minimal webbing, and cloacal region looks glandular. Dorsal surfaces are finely granular. Elongated, low dorsal ridges are present, concentrated around suprascapular region. Ventral surfaces of trunk, head, throat, and limbs mostly appear smooth, with the posterior trunk and medial thighs being granular (Brown and Gonzalez 2007).

In life Platymantis diesmosi is dark brown with tiny white flecks and/or irregular darker brown markings, or nearly black marbled with brown and having gold highlights. (One female paratype was tan with indistinct yellowish dorsolateral stripes and a distinct white vertebral stripe.) Limbs are golden brown with black transverse bands. On the head, golden flecks highlight the edge of the canthus rostralis, vertical labial bars, tip of snout, and tympanum. Digits are black with golden brown spots and cross bars around joints, on the dorsal surfaces. Throat color ranges from dark brown to cream with brown marbling. Chest and belly range from dark brown with white flecking, to pale cream. Ventral surfaces of forelimbs and hindlimbs are medium gray with darker boundaries. Palmar and plantar areas of hands and feet are purplish gray and have pale gray tubercles. Iris looks golden above pupil, and golden brown below pupil (Brown and Gonzalez 2007).

In preservative, the dorsal ground color on head and body is uniformly dark brown with gray patches. Dorsal surfaces of limbs are medium brown with transverse dark brown bars. Throat region is dark brown with white flecks. Chest is pale brown with black wrapping around anterior surface of upper arms. Venter is pale gray with dark gray spots that diminish in size posteriorly towards the homogeneous gray groin. Thigh is reddish brown, shank and tarsus are uniformly brown. Palmar and plantar surfaces of hands and feet are brown with gray subarticular tubercles. Iris turns pale gray (Brown and Gonzalez 2007).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Philippines

View distribution map in BerkeleyMapper.

Platymantis diesmosi is endemic to Mt. Malinao, on the Bicol Peninsula on Luzon Island, in the Philippines. This species resides on cliff and ravine edges, up to 30-40m away from water, in moist lower montane dipterocarp forest at 900-1,160m asl (Brown and Gonzalez 2007).

Life History, Abundance, Activity, and Special Behaviors
Platymantis diesmosi is terrestrial. Calling males were observed over an eight-day period restricted to the edge of steep cliffs along deep arroyo-like creek ravines. At Tiwi calling males faced towards the forest, away from the edges of cliffs, and calls were audible 50-75 m away. In general, advertisement calls only occurred on quiet nights following rainfall, and not during periods of heavy rain or high wind. Calling began about one hour after sunset and lasted for 2-4 hours. The advertisement call is amplitude-modulated and rapidly pulsed, sounding like a series of harsh, accelerating clicks "Er…er…er–er–ererer…" (Brown and Gonzalez 2007).

Trends and Threats
Extensive slash-and-burn shifting agriculture and selective logging (timber poaching) were observed throughout mid-montane elevations on Mt. Malinao, near the type locality. In 2001 disturbances reached 100m below the type locality and presumably will continue upward. The forest is owned by a private geothermal company (Brown and Gonzalez 2007).

Relation to Humans
Mt. Malinao supplies the majority of fresh water to the municipality of Tiwi, so disturbance of the fragile habitat will affect not only survival of Platymantis diesmosi but also the availability of fresh water for people living in the Tiwi watershed (Brown and Gonzalez 2007)

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing

Comments
Platymantis diesmosi is named after Arvin C. Diesmos, who has discovered many Philippine Platymantis species and who has identified at least that many undescribed species in his study of Philippine amphibian diversity, conservation, and ecology (Brown and Gonzalez 2007).

References

Brown, R. M. and Gonzalez, J. C. (2007). ''A new forest frog of the genus Platymantis (Amphibia: Anura: Ranidae) from the Bicol Peninsula of Luzon Island, Philippines.'' Copeia, 2007, 251-266.

Species Account Citation: AmphibiaWeb 2009 Platymantis diesmosi: Mt. Malinao Forest Frog <https://amphibiaweb.org/species/6910> University of California, Berkeley, CA, USA. Accessed Nov 22, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 22 Nov 2024.

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