Taxonomic Revision of Scaly-toed Geckos (Reptilia: Gekkonidae: Lepidodactylus) in the Northern Philippines, with Descriptions of Four New Species

Philippine herpetology (Amphibia, Reptilia), 20 years on: two decades of progress towards an increasingly collaborative, equitable, and inclusive approach to the study of the archipelago's amphibians and reptiles

A first review of the history, status, and prospects for Philippine herpetology conducted more than two decades ago (2002) summarized the diverse topics studied and highlighted the development and achievements in research up to the year 2000. This study revisits and re-assesses what Philippine herpetology has accomplished, both as a discipline and a community, during the last two decades (2002-2022). A total of 423 herpetological publications was collated, revealing a substantial increase in annual publications, rising from approximately four per year during 2002-2008 to around 28 per year in 2009-2022. Half of the published studies focused on squamate reptiles (lizards 30.5%, snakes 21%) and 28.4% on amphibians, 5.9% on turtles, and 2.6% on crocodiles. The remaining 11.6% of studies focused simultaneously on multiple taxa (i.e., faunal inventories). Diversity and distribution (35.2%) and ecological (26.5%) studies remained popular, while studies on taxonomy (14.9%), phylogenetics and biogeography (11.8%), and conservation (11.6%) all increased. However, geographical gaps persist urging immediate surveys in many understudied regions of the country. Finally, we found a balanced representation between Filipino and foreign first authors (1.0:1.1), yet a substantial gender gap exists between male and female first authors (7.1:1.0). Nonetheless, the steep increase in publications and the diversity of people engaged in Philippine herpetology is a remarkable positive finding compared to the 20 years preceding the last review (1980-2000). Our hope is that the next decades will bring increasingly equitable, internationally collaborative, and broadly inclusive engagement in the study of amphibians and reptiles in the Philippines.

A new species of Lepidodactylus (Squamata: Gekkonidae) from Umboi Island, Papua New Guinea

We describe a new species of Lepidodactylus from Umboi Island, just to the west of New Britain. It is a member of the Lepidodactylus guppyi Group and can be distinguished from all other Melanesian Lepidodactylus by aspects of digital scalation, digital webbing, enlarged femoral/precloacal scales, and color pattern. It is genetically distinct from its closest congeners, and genetic and morphological data indicate that the new species is most similar among named species to Lepidodactylus guppyi from the Solomon Islands, but it diverged from this species and other close relatives approximately 8 MYA or longer at a time prior to the existence of the island that it now occupies. The new species is known from only three individuals collected on a single tree, and efforts to find more animals in what seemed good habitat nearby were unsuccessful. This duplicates the pattern of apparent rarity seen for many Lepidodactylus species. Sufficient habitat exists on Umboi Island for arboreal geckos, suggesting that the species is not actually endangered but is ecologically cryptic. However, lack of needed information leads us to assess this species' conservation status as Data Deficient.

Cryptic extinction risk in a western Pacific lizard radiation

Cryptic ecologies, the Wallacean Shortfall of undocumented species' geographical ranges and the Linnaean Shortfall of undescribed diversity, are all major barriers to conservation assessment. When these factors overlap with drivers of extinction risk, such as insular distributions, the number of threatened species in a region or clade may be underestimated, a situation we term 'cryptic extinction risk'. The genus Lepidodactylus is a diverse radiation of insular and arboreal geckos that occurs across the western Pacific. Previous work on Lepidodactylus showed evidence of evolutionary displacement around continental fringes, suggesting an inherent vulnerability to extinction from factors such as competition and predation. We sought to (1) comprehensively review status and threats, (2) estimate the number of undescribed species, and (3) estimate extinction risk in data deficient and candidate species, in Lepidodactylus. From our updated IUCN Red List assessment, 60% of the 58 recognized species are threatened (n = 15) or Data Deficient (n = 21), which is higher than reported for most other lizard groups. Species from the smaller and isolated Pacific islands are of greatest conservation concern, with most either threatened or Data Deficient, and all particularly vulnerable to invasive species. We estimated 32 undescribed candidate species and linear modelling predicted that an additional 18 species, among these and the data deficient species, are threatened with extinction. Focusing efforts to resolve the taxonomy and conservation status of key taxa, especially on small islands in the Pacific, is a high priority for conserving this remarkably diverse, yet poorly understood, lizard fauna. Our data highlight how cryptic ecologies and cryptic diversity combine and lead to significant underestimation of extinction risk.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10531-022-02412-x.