Overview

Comprehensive Description

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).

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).

  • 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.
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Biology

Frogs of the genus Platymantis have two geographic centers of diversity and endemism. One large group of species occurs in the Solomon Islands and nearby Bismarck and Admiralty archipelagos (26 species). Another large group of species occurs in the Philippines (29 species). Outside of these two large archipelagos, one species occurs in Palau, seven or eight are known from New Guinea faunal region, two to four species occur in eastern Indonesia, and two species occur in Fiji (for review, see Siler et al., 2010). All species have direct development as the mode of reproduction, with direct-developing egg masses deposited in forest habitat on leaves, moss, twigs, and branches, as well as within leaf litter, and in rocky crevices in limestone outcrops.

Within the Philippines, three species groups are recognized on the basis of external morphology (W. C. Brown et al., 1997a,b; Alcala and W. C. Brown, 1999): the Platymantis dorsalis Group, the P. hazelae Group, and the P. guentheri Group. In addition to the morphological variation among Platymantis in the Philippines, the advertisement calls and preferred microhabitats of the species also vary (R. M. Brown et al., 2002; R. M. Brown and Gonzales, 2007). Surveys have shown that the highly distinctive limestone-forest habitats of the Philippines possess a great diversity of Platymantis and many endemic species (W. C. Brown and Alcala, 1982; R. M. Brown and Alcala, 2000; Siler et al., 2007, 2010).

The Platymantis hazelae Group, as currently recognized, consists of eight species endemic to the Philippines: P. hazelae, P. isarog, P. lawtoni, P. montanus, P. panayensis, P. polilloensis, P. sierramadrensis, and P. subterrestris. Members of this species group have been traditionally diagnosed on the basis of the following combination of characters: 1) terminal phalanx a wide "T"; 2) disks of fingers, except first, broadly dilated; 3) first finger much shorter than second, not reaching beyond midpoint between subarticular tubercle and disk; 4) digits proximal to disks much broader than deep, the result of wide dermal flanges; 5) subarticular tubercles large, round, and only moderately protruding; and 6) toe disks smaller than finger disks (Character and character states for the P. hazelae Group taken from Brown et al., 1997).

The Platymantis guentheri Group, as currently recognized, consists of ten species endemic to the Philippines: P. banahao, P. bayani, P. biak, P. cornutus, P. diesmosi, P. guentheri, P. insulatus, P. luzonensis, P. negrosensis, and P. rabori. Members of this species group have been traditionally diagnosed on the basis of the following combination of characters: 1) terminal phalanx a moderate to wide "T"; 2) disks of fingers, except first, moderately to broadly dilated; 3) first finger shorter than second, reaching as far as base of disk for some species; 4) digits proximal to disks about as deep as broad, the result of narrow, dermal flanges; 5) subarticular tubercles large and strongly protruding; and 6) toe disks about as broad to half as broad as finger disks (Character and character states for the P. guentheri Group taken from Brown et al., 1997).

The Platymantis dorsalis Group, as currently recognized, consists of twelve species endemic to the Philippines: P. cagayensis, P. corrugatus, P. dorsalis, P. indreprensus, P. levigatus, P. mimulus, P. naomiae, P. paengi, P. pseudodorsalis, P. pygmaeus, P. spelaeus, and P. taylori. Members of this species group have been traditionally diagnosed on the basis of the following combination of characters: 1) terminal phalanx bluntly rounded to pointed; 2) tips of fingers blunt, without disks, or with small to moderate disks; 3) first finger slightly shorter, about as long as, or longer than second; 4) digits proximal to disks about as deep as broad; 5) subarticular tubercles large, strongly protruding and frequently pointed; and 6) finger disks smaller than to slightly larger than toe disks (Character and character states for the P. dorsalis Group taken from Brown et al., 1997).

The currently recognized species diversity for the genus, especially within the Philippines, is likely underestimated. Future fine-scale studies of inter-population diversity, as well as studies incorporating genetic data will likely result in the discovery of numerous new, undescribed species. Although the three species groups recognized in the Philippines have long been a useful tool for diagnosing species based on external morphology, it is quite possible that these species groups are not monophyletic, and future studies may reveal phylogenetic patterns inconsistent with our current understanding of species diversity within the genus Platymantis.

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Distribution

Range Description

This species is known only from Mount Malinao, in the municipalities of Tiwi and Malinao, Albay Province, on the Bicol Peninsula, in the south of Luzon Island, in the Philippines, between 900 and 1,160m asl (Brown and Gonzalez, 2007). It is presumed to have a small distribution, but might occur more widely on the central geological component of the Bicol peninsula (for example on Mounts Isarog, Bulusan and Labo). It could possibly occur even further afield on Catanduanes and the Caramoan Peninsula.
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Distribution and Habitat

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).

  • 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.
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Type Locality

Philippines, Luzon Island, Albay Province, municipality of Tiwi, Barangay Banshaw, Sitio Purok 7, area known locally as 'Tamagong,' 950 m above sea level, NW slope of Mt. Malinao, 13° 26′ 12″ N, 123° 35′ 24″ E; type stored in the Philippine National Museum: PNM 8499

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Faunal Affinity

Luzon Pleistocene Aggregate Island Complex (PAIC; Brown and Diesmos, 2002).

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This species is known only from Mt. Malinao in the Bicol Peninsula of Luzon Island, Philippines.

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Physical Description

Diagnostic Description

Platymantis diesmosi can be distinguished from congeners by the following combination of characters: (1) greatly expanded digital disks absent; (2) dorsal skin rugosity absent to granular; (3) dorsal dermal tubercles absent; (4) dorsal folds/ridges absent; (5) tympanum hidden on posterodorsal edge; (6) supratympanic fold smooth, less prominent; (7) dorsolateral stripes absent; (8) spotted flanks absent; and (10) microhabitat preference for ground, cliff edges. (Character and character states follow Siler et al. 2009)

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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
This species is currently known only from mid-elevational transitional forest between lower- and mid-montane
dipterocarp forest communities (Brown and Gonzalez, 2007). Calling males exhibit a microhabitat preference unique among Philippine Platymantis, calling solely from the edge of steep cliffs along deep arroyo-like creek ravines (Brown and Gonzalez, 2007). These frogs were observed at the upper edges of a few cliffs, 15–35m above the level of the water below, and were situated only on dry patches of soil directly underneath the overhanging edge of the cliffs’ upper lip. Calling males face out into the forest, away from the cliff edge, and calls could be heard 50–75m away in the forest below (Brown and Gonzalez, 2007). In one locality, specimens were only collected 30–40m away from water, at the upper edge of a slope (Brown and Gonzalez, 2007). Despite extensive searches below and above cliff ledges on the plateau above, individuals were only encountered along the narrow strip of exposed soil at the edge of the overhanging and collapsing cliff edge (Brown and Gonzalez, 2007). The predominant vegetation is lower montane rainforest, the dominant trees being Podocarpaceae (Podocarpus>, Dacycarpus), Lauraceae, some Moraceae, Fabaceae (Lithocarpus) and Melastomaceae (Medenilla), with some stilt-rooted Pandanaceae (Pandanus), and many epiphytic shrubs, ferns, and orchids with moderate to thick moss cover on branches and trunks (Brown and Gonzalez, 2007). During surveys on Mount Malinao, biologists spent several weeks at the lower edge of the forest (approx. 700–800m asl) and at higher elevations between the type locality and the mountain’s peak (1,550m als), but Platymantis diesmosi was only encountered between 900 and 1,160m asl (Brown and Gonzalez, 2007). It has not been found outside forest. It is presumed to breed by direct development without dependence on water.

Systems
  • Terrestrial
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This species prefers ground microhabitats on the edges of cliffs in primary- and secondary-growth forest.

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Life History and Behavior

Reproduction

All species have direct development as the mode of reproduction, with direct-developing egg masses deposited by females in forest habitat.

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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
DD
Data Deficient

Red List Criteria

Version
3.1

Year Assessed
2008

Assessor/s
Rafe Brown

Reviewer/s
Simon Stuart, Neil Cox

Contributor/s

Justification
Listed as Data Deficient since it has only recently been described, and there is still very little known about its extent of occurrence, area of occupancy, status and ecological requirements.
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Population

Population
It is a very common species locally.

Population Trend
Unknown
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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…erâ€"erâ€"ererer…" (Brown and Gonzalez 2007).

  • 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.
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Threats

Major Threats
The available evidence suggests that this species is restricted to a single habitat type: the transition zone between lower- and mid-montane dipterocarp forests (Brown and Gonzalez, 2007). Near the type locality, extensive slash-and-burn shifting agriculture and selective logging is taking place throughout mid-montane elevations on Mount Malinao (Brown and Gonzalez, 2007). In 2001, the type locality was barely 100m above some of the most severe disturbances on the eastern face of Mount Malinao, and it is feared that continued degradation of the forest edge at this site will soon extend upwards to the type locality (Brown and Gonzalez, 2007). Because this area also supplies the majority of freshwater to the municipality of Tiwi, continued and unchecked exploitation of this fragile transition zone habitat will threaten not only the continued existence of Platymantis diesmosi, but also the future availability of freshwater for humans in the Tiwi watershed (Brown and Gonzalez, 2007). In addition to agricultural expansion, extensive timber poaching is taking place within the forest.
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Life History, Abundance, Activity, and Special Behaviors

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).

  • 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.
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Management

Conservation Actions

Conservation Actions
The forest on Mount Malinao is not formally protected, butis owned by a private geothermal company, which protects it to a certain extent by keeping out squatters. However, conservation initiatives aimed at protecting habitat of this species are urgently needed, and could also guarantee the future supply of clean water for the human populations surrounding the southern and eastern foothills of Mount Malinao (Brown and Gonzalez, 2007).
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Relevance to Humans and Ecosystems

Risks

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)

  • 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.
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Wikipedia

Platymantis diesmosi

Platymantis diesmosi is a species of frog that was first described by Brown and Gonzalez in 2007. It is endemic to the Philippines and is found on Malinao Volcano.[2]

Distribution and habitat[edit]

Platymantis diesmosi has only been found on Malinao Volcano in the Bicol Region of the Philippines at elevations of 900 and 1,160 m (2,950 and 3,810 ft) above mean sea level, where it is common. The International Union for Conservation of Nature has classed the species as "Data Deficient" because it was described recently and not much data has been collected.[1] The species has been found between 30 and 40 metres (98 and 131 ft) away from water, and on cliff edges.[3][4]

Description[edit]

Females have a snout-vent length of 49.8 to 52.7 mm (1.96 to 2.07 in), while the corresponding measurement for males is 28.3 to 39.1 mm (1.11 to 1.54 in). The tip of the snout extends just over the lower jaw and is pointed bluntly. The arms are slender and the fingers are long and black with brown-gold spots.[3] The lips are swollen. The pupil of the eye is horizontally elliptical. P. diesmosi is mainly dark brown and has irregular darker markings and/or minuscule white patches. Specimens are sometimes almost totally black and brown with golden highlights. Golden patches can be found on the head, and its limbs are mainly golden-brown. The throat colour ranges from cream to dark brown, and the chest and stomach are also variably coloured, from dark brown with white patches to cream.[3]

References[edit]

  1. ^ a b Rafe Brown (2008). "Platymantis diesmosi". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 22 February 2014. 
  2. ^ Frost, Darrel R. (2014). "Platymantis diesmosi Brown and Gonzalez, 2007". Amphibian Species of the World: an Online Reference. Version 6.0. American Museum of Natural History. Retrieved 22 February 2014. 
  3. ^ a b c "Platymantis diesmosi". AmphibiaWeb. 2009-02-22. Retrieved 2012-12-01. 
  4. ^ "Platymantis diesmosi | PhilBREO". Philbreo.lifedesks.org. Retrieved 2012-12-01. 
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