Abstract
Exposed limestone karst landscapes, especially in the tropics, are often home to distinctive and specialized biotas. Among vertebrates, a particularly large number of karst-associated lizard taxa have been described, but for the vast majority, evidence of specific adaptions to karst is lacking. A number of studies, however, have provided evidence of consistent morphological trends in lizards that use complex, three-dimensional, saxicoline habitats such as those that typify karst areas. Here we combine morphological and genetic data to test whether a newly discovered gecko from an extremely rugged karst area in New Guinea shows morphological trends matching those observed in other lizards associated with complex rock habitats such as karst and caves. Consistent with predictions, the new species' head is flatter and narrower than similar-sized relatives, and it has proportionally larger eyes and longer limbs. These trends indicate this taxon represents the second documented instance of karst specialization in a New Guinean vertebrate, and suggest morphological traits to test for evidence of specialized ecological associations in the many karst-associated Cyrtodactylus taxa from Southeast Asia.
Highlights
Large areas of exposed limestone karst in tropical regions present spectacular landscapes, and are home to unique, endemic and putatively specialized local biotas in Madagascar [1], Southeast Asia [2] and Australia [3,4]
Types have been lodged at Museum Victoria or the South Australian Museum, and two additional samples are to be repatriated to the Papua New Guinea National Museum
Based on moderate statistical support (ML bootstrap 81%, Bayesian posterior probability 1.0), it is part of a recently identified clade of medium-sized, forestdwelling species found in the mountains/hills of central and northern New Guinea (Cyrtodactylus capreoloides, Cyrtodactylus boreoclivus and Cyrtodactylus medioclivus) [31]
Summary
Large areas of exposed limestone karst in tropical regions present spectacular landscapes, and are home to unique, endemic and putatively specialized local biotas in Madagascar [1], Southeast Asia [2] and Australia [3,4]. Lizards often show a close association with karst landforms, including numerous taxa that have only been described recently [5,6,7,8,9,10]. Adaptive processes led formerly more generalist lineages to become ecological specialists, restricted to the topographically complex, nutrient-poor and biologically distinctive habitats provided by karst [2,11]
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