Amphibians and Reptiles , Romblon Island Group , central Philippines : Comprehensive herpetofaunal inventory

We present results from several recent herpetological surveys in the Romblon Island Group (RIG), Romblon Province, central Philippines. Together with a summary of historical museum records, our data document the occurrence of 55 species of amphibians and reptiles in this small island group. Until the present effort, and despite past studies, herpetological diversity of the RIG and their biogeographical affinities has remained poorly understood. We report on observations of evolutionarily distinct amphibian species, including conspicuous, previously known, endemics like the forest frogs Platymantis lawtoni and P. levigatus and two additional suspected undescribed species of Platymantis . Moderate levels of reptile endemism prevail on these islands, including taxa like the karst forest gecko species Gekko romblon and the newly discovered species G. coi . Although relatively small and less diverse than the surrounding landmasses, the islands of Romblon Province contain remarkable levels of endemism when considered as percentage of the total fauna or per unit landmass area.


Introduction
The Romblon Island Group (RIG) is a small assemblage of islands located in the central Philippines between three major faunal regions (Luzon, Mindoro, and Visayan Pleistocene Aggregate Island Complexes (PAICs; Brown and Diesmos 2002;2009; Figure 1).The largest landmasses in this group are the islands of Romblon, Tablas, and Sibuyan (Figure 1).Geologically, these islands, along with the Buruanga Peninsula of northwest Panay Island and the southwestern portion of Mindoro Island, were part of the North Palawan Terrain, itself a part of the Palawan microcontinental block that migrated across what is now the South China Sea following its separation from Asia (Zamoras and Matsuoka 2004;Zamoras et al. 2008).The complex, mobile geological history of these central Philippine landmasses has been discussed in the context of the impact that crustal movements, spreading rift zones, and subduction patterns (Yumul et al. 2003;2009) may have had on the distribution of life in today's central Philippines (Brown and Guttman 2002;Brown et al. 2009a;Blackburn et al. 2010;Esselstyn et al. 2010;Siler et al. 2012).Additionally, more recent (Pleistocene) sea level oscillations may have impacted the distribution of some of the island group's species.For example, it is known that Romblon and Tablas were conjoined to the exclusion of Sibuyan at multiple points during the last 500,000 years (Voris 2000).
Owing to its central position in the Philippine archipelago, the fauna of the RIG is of particular interest to biogeographers (Goodman et al. 1995).Having not been connected to the larger, surrounding landmasses, these islands must have experienced faunal development as a result of cross-water dispersal from Luzon, Mindoro, and the islands of the western Visayas (in particular northern Panay).The birds and mammals of the region (Goodman Abstract: We present results from several recent herpetological surveys in the Romblon Island Group (RIG), Romblon Province, central Philippines.Together with a summary of historical museum records, our data document the occurrence of 55 species of amphibians and reptiles in this small island group.Until the present effort, and despite past studies, herpetological diversity of the RIG and their biogeographical affinities has remained poorly understood.We report on observations of evolutionarily distinct amphibian species, including conspicuous, previously known, endemics like the forest frogs Platymantis lawtoni and P. levigatus and two additional suspected undescribed species of Platymantis.Moderate levels of reptile endemism prevail on these islands, including taxa like the karst forest gecko species Gekko romblon and the newly discovered species G. coi.Although relatively small and less diverse than the surrounding landmasses, the islands of Romblon Province contain remarkable levels of endemism when considered as percentage of the total fauna or per unit landmass area.islands of the three major, recognized faunal regions surrounding the province: the Luzon Pleistocene Aggregate Island Complex (PAIC; Brown and Diesmos 2002;2009), the Mindoro PAIC, and the Visayan PAIC.We computed Simpson similarity indices (S) using the formula S = C/N, where C is the number of species common to both islands in the RIG, or the island in the RIG and the respective PAIC, and N is the number of species on the island of interest (Cheatham and Lazell 1969).Species lists were based on Brown (2007), Siler (2011), Frost (2011) and Siler, Brown, Diesmos, and Oliveros (unpublished data) for the Luzon, Mindoro and Negros-Panay PAICs.1).Elevation contours are indicated with incremental shading, and sampling localities are indicated by black circles.Question marks denote historical island records referenced but with unknown locality information.

Bufonidae
Rhinella marina (Linnaeus, 1758) We collected individuals of this introduced and invasive species at two localities on Tablas Island and observed specimens in agricultural areas near the Mt.Guiting-Guiting National Park headquarters on Sibuyan (specimens not collected).This introduced (Diesmos et al. 2006) species is common in highly disturbed habitats and can often be heard breeding in loud choruses in flooded agricultural fields.Location T6: KU 301835; Location T3: KU 301818.

Dicroglossidae
Fejervarya moodei (Taylor 1920) This widespread endemic Philippine species is common in disturbed habitats in coastal areas.We observed F. moodei on Tablas, Sibuyan, and Romblon.Additionally, this species has been reported from Carabao Island.Our specimens from Romblon are new records for this island.Fejervarya vittigera (Wiegmann, 1834) Fejervarya vittigera is a widespread endemic species common in disturbed habitat.We collected individuals of this species on Tablas, Sibuyan, and Romblon islands, all representing new records for these islands.Location R3: KU 302067; Location T3: KU 302026-302027; Location T4: KU 315245-315250; Location T7: KU 315234-315244.
Limnonectes cf.leytensis (Boettger, 1893) Limnonectes cf.leytensis has been recorded on the islands of Tablas, Sibuyan, and Carabao.Individuals were found near water sources ranging from small temporary pools, to the banks of streams to marshes and flooded areas.On the Visayan islands of Negros and Panay, Limmonectes cf.leytensis demonstrates a microhabitat preference for swamps (Alcala and Brown 1998), but on Sibuyan Island it has been observed exclusively in riparian, streamside habitats (RMB, ACD and CDS, pers.obs.).Our specimens from Tablas are new records for this island.

Occidozyga laevis (Günther, 1858)
A common puddle frog, this species is found throughout the Philippines in shallow, slow-moving streams, small pools of water in disturbed habitat, and in small stagnant pools (i.e.puddles in forests to water buffalo wallows in agricultural areas).We collected this species in shallow pools of water in agricultural and residential areas on Tablas, Romblon, and Sibuyan.Our specimens from Romblon are new records for this island.

Ranidae
Hylarana erythraea (Schlegel, 1837) This wide ranging, non-native Philippine species (Diesmos et al. 2006) was found on the islands of Tablas, Sibuyan and Romblon around temporary or stagnant water sources.Specimens were observed in heavily disturbed habitat and residential areas as well as near the edges of second growth forest.Our specimens from Romblon are new records for this island.

Rhacophoridae
Polypedates cf.leucomystax (Gravenhorst, 1829) Locally referred to as the Palakang Saging (or Banana Frog), Polypedates cf.leucomystax is an arboreal species found usually in disturbed habitat and residential areas around temporary pools of water.The species has been recorded on Tablas, Romblon, Sibuyan, and Carabao.A recent phylogenetic study of the species revealed nearly all populations in the Philippines to be genetically identical to one another, an indication that the species may have recently invaded the Philippines, possibly due to humanmediated dispersal (Brown et al. 2010)

Rhacophorus pardalis Günther, 1858
This species of arboreal gliding frog was observed in disturbed to second growth forest habitat on the island of Tablas.In other parts of its range, this species can be observed in large aggregations on shrubs, trees, and saplings around temporary pools of water after heavy rains (CDS and RMB, pers.obs.).The single specimen collected represents a new island record for Tablas, as well as the first observation of Rhacophorus pardalis in Romblon Province.Location T2: KU 315336.

Reptilia (Lizards)
Agamidae Bronchocela marmorata (Kuhl, 1820) We found this species asleep at night on branches of trees and shrubs in disturbed forest and bushes surrounding agricultural areas 2-4 m above the ground.This species is widely distributed in the Philippines.Hydrosaurus pustulatus (Eschscholtz, 1829) We collected individuals of this species at night on branches over streams.This species of sailfin lizard is known to occur on all major, and many small and isolated,

Gekkonidae
Cyrtodactylus philippinicus (Steindachner, 1867) This species is endemic to the northern and west-central islands of the Philippines.We encountered these lizards on Tablas, Romblon and Sibuyan islands.Our specimen from Romblon is a new record for the island.A comprehensive phylogenetic study of Philippine Cyrtodactylus species based on DNA sequence data demonstrated that samples from the RIG form a clade (Siler et al. 2010a).However, it was unclear from this work whether lizards from the island group were more closely related to populations from Mindoro or from Negros and Panay.Gekko coi Brown, Siler, Oliveros, Diesmos and Alcala, 2011 This newly described species from Sibuyan was collected on tree trunks among the limestone outcrops in secondary to primary growth forest (Brown et al. 2011).Individuals were also observed in and around cave systems.Similar to G. romblon, the conservation status of this single island endemic species should be evaluated.
Gekko gecko (Linnaeus, 1758) This taxon is known to occur throughout the Philippines with the exception of the Batanes and Babuyan Island groups (CHO, pers.obs.).Specimens have been collected on Tablas, Sibuyan, Maestro de Campo, and Carabao.Specimens from Sibuyan and Maestre de Campo represent new island distribution records.Gekko mindorensis Taylor, 1919 This species has a wide distribution throughout the Philippine islands.The diversity within Philippine species in the genus Gekko has steadily increased over the years (Rösler et al. 2006;Brown et al. 2008;2009b;2011;Siler et al. in press), and G. mindorensis may eventually prove to be a complex of cryptic species.We collected individuals of this species on Maestre de Campo, and a specimen has previously been collected on Sibuyan.Location M1: KU 302733-302735, 305137; Location S9: FMNH 251109.
Gekko romblon Brown and Alcala, 1978 This species has been historically recognized to occur on the islands of Romblon, Tablas, and Sibuyan in the RIG.The description of this Philippine endemic was based on specimens from Tablas (type locality: holotype CAS 139190) and Sibuyan islands.Recently, additional material from Romblon and further examination of specimens and genetic data revealed that individuals from Sibuyan represented a new species, distinct from the geckos of Tablas and Romblon (Brown et al. 2011; see Gekko coi above).The conservation status of this highly restrictedrange species needs urgent evaluation.Although two specimens from Carabao Island are listed as G. romblon (CAS 128163 and 128175), we are hesitant to recognize this population as true G. romblon, and close inspection of these individuals is needed for proper identification.Given that the Maestre de Campo Island population of Gekko have been identified as part of the G. mindorensis complex

Hemidactylus frenatus Schlegel, 1836
This house gecko occurs throughout the Philippine archipelago and has been collected on Tablas, Sibuyan,  Pseudogekko compressicorpus (Taylor, 1915) This species is a rarely encountered gecko that prefers to perch on aerial ferns or shrubs not far from the ground.It is a slender, arboreal species that has only been documented on Tablas in Romblon Province but is otherwise found on Luzon, Samar, Leyte, Bohol, and Mindanao.It is noteworthy that P. compressicorpus appears to replace the normallyencountered Visayan PAIC endemic species P. brevipes on Tablas.Location T1: CAS 139713.

Scincidae
Brachymeles cf.bonitae Duméril and Bibron, 1836 Brachymeles cf.bonitae is a limb-reduced species of skink that is often encountered under rotting logs and in loose soil surrounding the root networks of large trees.This species, as currently recognized, is widely distributed across the northern Philippine islands (Siler and Brown 2010).Recent phylogenetic studies of the genus Brachymeles have not supported its monophyly (Siler et al. 2011a;Siler and Brown 2011).The species likely represents a complex of morphologically similar but unique evolutionary lineages worthy of taxonomic recognition.Unlike many species in the genus, B. bonitae appears to be a forest obligate, and in the RIG, specimens have been collected on the islands of Tablas and Sibuyan.Location S8: CAS 137053; Location S10: FMNH 251123; Location T1: MCZ 44152; Location T11: CAS 137148-137154.Brown, 1956 Individuals of this common Visayan PAIC endemic species were found in secondary-to primary-growth forest and disturbed habitat on the islands of Tablas, Sibuyan, and Carabao.Specimens were observed under piles of rotting coconut shells, as well as within and beneath rotting logs.Siler and Brown (2010), recently redescribed this species, using molecular phylogenetic analyses to infer its relationships to other Brachymeles (Siler et al. 2011b;Siler and Brown 2011) Brachymeles tridactylus Brown, 1956 Brachymeles tridactylus has been documented from a range of habitats from secondary-to primary forest, as well as disturbed habitats.This species has only been documented on Carabao Island; however, it is widely distributed in the Visayan (central) islands in the Philippines, often occurring sympatrically with B. talinis (Siler and Brown 2010).Although this three-digit species possesses a relatively broad distribution across the central Philippines in comparison to other non-pentadactyl species in the genus (B. cebuensis, B. muntingkamay, B. elerae, B. wrighti, B. pathfinderi, B. vermis, B. apus, B. miriamae, B. minimus, and B. lukbani), recent phylogenetic studies have supported the monophyly of populations spanning this distribution (Siler et al. 2011a;Siler and Brown 2011) and, thus we recognize this lineage as a single species.Location Ca1: CAS 128145-128150, 128160-128161. Eutropis multifasciata (Kuhl, 1820) This species is known to occur throughout the Philippines.We collected individuals of this species on leaf litter material in disturbed habitats on the islands of Tablas and Sibuyan.This species exhibits sexual dichromatism, with males possessing varying patches of brightly colored scales on the lateral surfaces of their body (CDS and RMB, pers.obs.).Three specimens identified as Eutropis cf.multicarinata borealis (MCZ 26602-26604) are reported from Tablas; however, the subspecies has never been documented from Romblon Province (Brown and Alcala 1980).Closer inspection should be made for definitive identification, as they may represent E. multifasciata.Lamprolepis smaragdina philippinica (Mertens, 1928) Specimens of this arboreal species were found to occur in disturbed habitat only, usually on the forest edge in open canopy.Many specimens were collected in coconut groves 2-6 m above the ground.The species has been reported to occur on every island surveyed in the RIG except for Cresta de Gallo Island.Body coloration among populations of this species is highly variable, with several populations known to be entirely green (Siler and Linkem 2011).Our records from Maestre de Campo and Romblon islands represent new island records for this species.Lipinia auriculata kempi (Taylor, 1919) Individuals of Lipinia auriculata kempi were found in secondary forest and more disturbed habitat along the forest edge on the ground or low on the trunks of trees.Specimens have only been collected from the island of Tablas.Location T11: CAS 137247-137252; Location T14: CAS 137289-137291.

Otosaurus cumingi (Gray, 1845)
The genus Otosaurus recently was resurrected from the synonymy of Sphenomorphus to accommodate the phylogenetically distinct, single, Philippine endemic lineage (Linkem et al. 2011).Otosaurus cumingi is a large species of ground dwelling skink.It has been collected only a few times in leaf litter on the slopes of Mt.Guiting-Guiting, on the island of Sibuyan.Location S8: CAS 139183; Location S10: FMNH 236051-54.

Parvoscincus decipiens (Boulenger, 1894)
Parvoscincus decipiens, formerly a member of the genus Sphenomorphus (Linkem et al. 2011), is often found in leaf litter on the forest floor.Specimens were collected in disturbed habitat and into secondary growth forest on Tablas, and the species has also been collected on Sibuyan.Location S10: FMNH 236147; Location T11: CAS 137285-137287; Location T14: CAS 137298-137301.

Parvoscincus steerei Stejneger, 1908
As with Parvoscincus decipiens, P. steerei was previously considered a member of the genus Sphenomorphus (Linkem et al. 2011).This small species can be found in secondary-and primary-forest in leaf litter.Specimens were collected on Sibuyan and Tablas.Ahaetulla prasina preocularis (Taylor, 1922) We collected this species of vine snake asleep on branches of shrubs in secondary-growth forest.This species is widely distributed in the Philippines (Leviton 1967); however, our collection on Tablas Island represents the first record from Romblon Province.Location T2: KU 315372.
Boiga cynodon (Boie, 1827) We collected this species in arboreal habitats in disturbed and secondary forest on Tablas Island.Individuals were encountered actively hunting at night on branches of trees and shrubs in the forest.This represents a new island record for this species, as it was previously recognized to occur only on the islands of Basilan, Culion, Dinagat, Leyte, Luzon, Mindanao, Palawan, Polillo, Sibutu, Panay, and in the Sulu Archipelago (Leviton 1963;1970;Alcala 1986;Ferner et al. 2000;Gaulke 2001).Location T2: KU 315373, 315382.Duméril, Bibron, and Duméril, 1854 This burrowing snake is often found in loose leaf litter around the root systems of large trees or under rotting logs.

Chrysopelea paradisi Boie, 1827
This species of arboreal, gliding snake has been documented to occur on Sibuyan and Tablas.Individuals in the Philippines are often found on the trunks and branches of trees.Location S1: USNM 36114; Location T2: KU 315377; Location T11: CAS 137180.Leviton, 1967 This species was collected under leaf litter and fallen logs in disturbed and second growth forest.As is currently recognized, this species is widely distributed in the northern and central Philippines and the subspecies is endemic to the Visayas (Leviton 1965b).Location T1: MCZ 25670-25674; Location T2: KU 315375; Location T11: CAS 137181-137184.

Dendrelaphis marenae Vogel and van Rooijen, 2010
A common vine snake in the Philippines, Dendrelaphis marenae was found on Carabao and Tablas, usually 2-4 m above the ground on branches and shrubs.Individuals were often encountered asleep at night coiled on branches.Location Ca1: CAS 128156-128157; Location T2: KU 315376; Location T11: CAS 137191.

Dryophiops philippina Boulenger, 1896
An uncommon snake recognized to occur on the islands of Bataan, Luzon, Mindoro, and Sibuyan.A singe specimen has been recorded from Sibuyan.Location S1: CM 2432

Lycodon capucinus Boie, 1827
We found individuals of this species under leaf litter and fallen logs in disturbed agricultural areas and secondary forest.Although there are five endemic Philippine species of snakes in the genus Lycodon, L. capucinus is recognized to have a broad distribution across much of Southeast Asia (Leviton 1965a).Location Ca1: CAS 128155; Location S8: CAS 137087; Location T2: KU 315378; Location T3: KU 305143; Location T11: CAS 137253.

Oligodon modestum Günther, 1864
This endemic species of Philippine terrestrial snake is recognized to occur on the islands of Luzon, Mindanao, Negros, Panay, and Tablas.A single specimen of this species is reported from Tablas.Location T9: MCZ 25726.

Elapidae
Laticauda colubrina (Schneider, 1799) The distinctively banded yellow-lipped sea krait, Laticauda colubrina, is a marine snake found in shallow marine environments throughout much of Southeast Asia, including the shallow seas throughout the Philippine archipelago.Specimens were collected off the shores of Maestre de Campo by fishermen, and represent the first records of this species from the shallow waters surrounding Romblon Province.

Homalopsidae
Cerberus rynchops (Schneider, 1799) Cerberus rynchops is a fully aquatic snake, found Typhlops ruficaudus (Gray, 1845) Typhlops ruficaudus is an endemic Philippine blindsnake, and has been documented on Sibuyan and Tablas in the RIG.This species has also been observed in the rotting organic material within and beneath rotting logs in primary forest.A single specimen identified as T. castanotus (MCZ 25595) has been documented from Tablas (Location T1).However, we believe the identification is in error, and this specimen likely represents T. ruficaudus, for two reasons.First, another specimen in the same collection series (MCZ 25594) has been identified as T. ruficaudus (A.Wynn, pers. comm.), and second, no other specimens of Typhlops castanotus have ever been documented from the Romblon Province, and the species is currently recognized to occur only on Inampulugan Island, Boracay Island and the northern coast of Panay Island, in the Negros-Panay PAIC (Wynn and Leviton 1993;A. Wynn, pers. comm.).Unfortunately, we have not examined this specimen; it may represent T. ruficaudus.Location S8: CAS 169879; Location T1: MCZ 25594, 25595; Location T11: CAS 169881.

Gerrhopilidae
Gerrhopilus hedraeus (Savage, 1950) This endemic Philippine blindsnake has been recorded on Tablas, in loose soil beneath a rotting log in primarygrowth forest.Previously recognized to be a member of Typhlops ater group, a recent phylogenetic study of blindsnakes justified the resurrection of the genus Gerrhopilus (Vidal et al. 2010).Location T11: CAS 169882.

Cuora amboinensis amboinensis Daudin, 1802
This species of Asian box turtle is commonly found along small river systems, in open fields and in temporary pools of water (Diesmos et al. 2008).Specimens were collected on Tablas and Sibuyan islands.According to the local government units and the Mt.Guiting-Guiting Natural Park staff on Sibuyan, the Sibuyan population of this species has historically experienced extreme hunting pressures and illegal poaching, which has drastically reduced local populations.This study presents the first records of this species from Tablas.Our surveys provide extensive new data on the diversity of amphibians and reptiles in Romblon Province (Table 2).The species encountered in the RIG include nine new records for Tablas, eight for Romblon, four for Sibuyan, and five for Maestre de Campo.This comprehensive review provides additional information on rare species known previously from few observations and specimens.This study provides additional support for the absence of rare species historically believed to be endemic to islands in the RIG.Specifically no species were observed that matched the description of Luperosaurus amissus Taylor 1962.Once believed to be endemic to Tablas (Taylor 1922a, b), this species of gecko is now recognized to be G. hokouensis Pope 1928, occurring in eastern China, Japan, and Taiwan (Brown and Alcala 1978;Ota et al. 1989), most likely attributed to the Philippines in error.Although much of the habitat we explored was secondary regenerating forest at best, moderate species diversity was encountered at all sites.At all sites visited, signs of low-level disturbances were apparent, included logging, swidden agriculture, and possible mining.The introduced species Rhinella marina was observed during our surveys, suggesting that this invasive species may also have been introduced to many small, isolated islands throughout the Philippines.
Because the islands of Romblon Province are situated between three major, recognized faunal regions in the Philippines (Luzon, Mindoro, and Negros-Panay PAICs), it is interesting to consider the degree to which each surrounding region has served as a biogeographic source for the unique herpetofauna of the RIG.The results of this study indicate that, with few exceptions, the Luzon and Visayan PAICs share the same degree of similarity with the islands of the Romblon Province (Table 3).The one exception is Carabao Island, which is more similar to the fauna from the Visayan PAIC.This comes as no surprise, however, as Carabao is located between Tablas and Panay (Figure 1).Interestingly, of the three major islands in the province, Sibuyan and Tablas share more faunal similarity with the Luzon and Visayan PAIC, than either island does with the Mindoro PAIC (Table 3).This is in contrast to Romblon Island, which shares the greatest faunal similarity with the Mindoro PAIC (Table 3).Romblon is located between the larger islands of Sibuyan and Tablas in the province, and its high degree of faunal similarity with the Mindoro PAIC seems counterintuitive.
Within the RIG, there is a high degree of faunal similarity between islands, with a few exceptions (Table 4).The island of Maestre de Campo is observed to have the lowest overall faunal similarity with other island members of the RIG (Table 4).This may be due to its proximity to the Mindoro PAIC, or its distance from the many islands in the RIG.Interestingly, two of the small islands sampled (Carabao, Maestre de Campo) share higher faunal similarities with Sibuyan and Tablas than they do Romblon (located in the center of the three big islands of the RIG (Table 4).The unique, patchy pattern of faunal similarity and endemism observed in this study provide opportunities for future studies focusing on the biogeography and species distributions in the region.
From the few published phylogenetic studies that include dense sampling of widely distributed species in the Philippines, several interesting patterns can be observed.In a recent phylogenetic study, the gecko species endemic to the RIG (Gekko romblon, G. coi) are recovered as sister lineages to species from the Luzon and Visayan PAICs (Siler et al. 2012).In the same study, Siler et al. (2012) recovered the Maestre de Campo population of Gekko mindorensis as one of eight deeply divergent, well-supported clades making up the G. mindorensis complex.The populations of G. mindorensis supported to be most closely related to the divergent population on Maestre de Campo were shown to all be from the Mindoro and Luzon PAICs (Siler et al. 2012).Interestingly, the same pattern has been observed for widespread species of geckos in the genus Cyrtodactylus (Siler et al. 2010a).The RIG populations of the widespread species C. philippinicus are supported (albeit with weak support) to be most closely related to populations from the Mindoro and Luzon PAICs (Siler et al. 2010a).
This study results in the recognition of 55 species of amphibians and reptiles from Romblon Province (Table 2).Although it contributes greatly to our knowledge of this unique herpetofauna, the resulting 26 new species records for Romblon Province highlight the fact that our current understanding of the region's diversity is still incomplete.Several small, isolated islands in the province have yet to be explored (e.g.Alad, Banton, Carlota, Cobrador, Isabel, Lugbung, Simara).Additionally, surveys should be undertaken on the small islands on which historical collections were made (Carabao, Cresta de Gallo) as the currently recognized diversity on these islands is surely underestimated.It remains to be seen whether the small islands of the Philippines will possess significant levels of endemic vertebrate diversity as has been reported from small islands adjacent to the Asian mainland (see Grismer and Onn 2010 for a review).The limited available evidence suggests that some smaller, land-bridge islands do possess endemic species (i.e.Gekko gigante [Brown and Alcala 1978] and Platymantis insulatus [Brown and Alcala 1970]) and it is clear that many small oceanic islands likewise possess highly distinctive endemics (Brown et al. 2008(Brown et al. , 2009b;;Oliveros et al. 2011).We suspect that future studies in the area, as well as continued research on the many unexplored islands in the province, will result in additional species distribution records and the possible discovery of new, endemic taxa.Many groups of amphibians and reptiles in Romblon Province warrant additional taxonomic study.These include species of the genera Platymantis, Brachymeles, Cyrtodactylus, Gekko, and Limnonectes, all of which contain widespread species with distributions spanning traditionally recognized faunal zone demarcations (Brown and Diesmos 2002;2009).Over the last ten years alone, studies involving just a few of these groups have resulted in the discovery of numerous new species (Brown et al. 2008;Brown and Guttman 2002;Rösler et al. 2006;Brown and Gonzalez 2007;Siler et al. 2007;Siler et al. 2009aSiler et al. , b, c, 2010b, c, d;, c, d;2011b;in press;Linkem et al. 2010a;Welton et al. 2009Welton et al. , 2010a, b), b).As the number of faunal descriptions for sites across the Philippines increase, and our understanding of the mechanisms driving diversification in the archipelago improves, we are gradually approaching a more thorough understanding of the evolutionary history of Philippine vertebrates (Brown and Diesmos 2009;Esselstyn and Brown 2009;Jansa et al. 2006;Linkem et al. 2010b;Siler et al. 2010aSiler et al. , 2011a, in press, in press).However, before truly informed conservation planning can be implemented, much taxonomic work remains to be completed in this island archipelago most likely characterize by vastly underestimated biodiversity (Brown and Diesmos 2009).

Figure 1 .
Figure 1.(Left) Map of the Philippines showing the five recognized major Pleistocene Aggregate Island Complexes (PAICs) and additional deep-water islands.Current islands in the Philippines are shown in medium grey; light gray areas enclosed in black 120 m bathymetric contours indicate the hypothesized maximum extent of land during the mid-to late Pleistocene.The location of Romblon Province in the central Philippines is outlined by a box.(B) Islands of the Romblon Province, showing the localities referenced in the study (Table1).Elevation contours are indicated with incremental shading, and sampling localities are indicated by black circles.Question marks denote historical island records referenced but with unknown locality information.

Figure 2 .Figure 3 .
Figure 2. A) View of shallow marine habitat off coast of Location M1; B) Coastal habitat at Location M1; C) Coastal habitat at Location M1; D) Coastal habitat at Location S4; E) View of Mt.Guiting-Guiting (Location S4); F) Forest habitat at Location S4.Photos by CDS and RMB.

Table 1 .
Localities visited in Romblon Province, Philippines listed by site number.
. Our specimens from Romblon are new records for this island.Figure11.
Draco quadrasi Boettger, 1893This species has been collected on the islands of Romblon and Sibuyan, and is quite common on the trunks and canopies of coconut trees.Draco quadrasi possesses a disjunct distribution in the Philippines, occurring in the Mindoro faunal region (Mindoro and Semirara islands) and on Romblon and Sibuyan in the RIG (but not Tablas, where it is replaced by D. spilopterus).

Table 4 .
Indices of herpetofaunal similarity among surveyed islands of the Romblon Island Group.