Taxonomy, Natural History, and Ecology of Selected Herpetofaunal Species from the Sunda Islands and Adjacent Regions – Synergistic Effects of Fieldwork and Museum Collections for Biodiversity Research
In this cumulative thesis (papers 1–13) I investigated the taxonomy, natural history, and ecology of selected species of amphibians and reptiles from the Sunda Islands and adjacent regions, and highlighted the importance of natural history collections for biodiversity research. Several Sundaic speci...
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|Summary:||In this cumulative thesis (papers 1–13) I investigated the taxonomy, natural history, and ecology of selected species of amphibians and reptiles from the Sunda Islands and adjacent regions, and highlighted the importance of natural history collections for biodiversity research. Several Sundaic species provided unexpected challenges, primarily because of significant problems stemming from their taxonomic history. Only the synergy of fieldwork and collection-based studies, allowed me to resolve some of these issues, as outlined below.
Herpetological surveys in all districts of Timor-Leste (except the Oecusse exclave), including its offshore islands, contributed towards a comprehensive inventory of the amphibians and reptiles of this country at the southern border of the Wallacea Biodiversity Hotspot. New distribution records of amphibians and reptiles for 11 of the country’s 12 contiguous districts, along with natural history data were presented. Results of the survey work increased the number of amphibian and reptile species known to occur in Timor-Leste to > 60, including > 20 candidate species. Many of the recorded species appear to be endemic to Timor Island, including the frog Kaloula sp. nov., several bent-toed gecko species of the genus Cyrtodactylus, and the agamid Draco timoriensis. Notable reptile discoveries included at least seven undescribed Cyrtodactylus species, a genus previously not recorded from Timor, the first records of the gecko Hemidactylus garnotii and of the gecko genus Hemiphyllodactylus for Timor-Leste, and several undescribed skinks (chapter 4, papers 1 & 2). Revisions of the genus Cyrtodactylus, and the skink genus Eremiascincus on Timor and adjacent islands, including the description of new species, are currently in preparation together with colleagues from the USA and the UK.
A revision of Timorese Cyrtodactylus is not possible without resolving the tangled taxonomy of some extralimital species. The taxonomy of selected non-Timorese Cyrtodactylus geckos was investigated accordingly, in three papers (chapter 5, papers 3–5). A new species of Cyrtodactylus, originally catalogued as C. fumosus in the herpetological collection of the Senckenberg Naturmuseum Frankfurt, Germany, was described from Klakah, Lumajang Regency, Jawa Timur Province, Indonesia. The new species differs from all other congeners by a combination of seven characters (paper 3). The Cyrtodactylus fauna of Java had been underestimated for centuries with four out of the five endemic species described as late as during the 2000s. Cyrtodactylus fumosus, hitherto considered widespread in the Sunda Archipelago, including the islands of Sumatra, Java, Bali, Sulawesi, and Halmahera, was redescribed and confirmed to possess a precloacal groove in males. Examination of the type specimen and additional vouchers from Rurukan and Mount Masarang, North Sulawesi Province, Indonesia, revealed that this population was distinct from other forms heretofore called ‘fumosus’ by a combination of unique morphological characters. Cyrtodactylus fumosus was identified as the most distinctive species among the six bent-toed geckos recorded from Sulawesi, differing from Sulawesi congeners by four striking characters (paper 5). Since there was also much taxonomic confusion of C. fumosus with
C. marmoratus, the type series of the latter taxon was described for the first time. I was able to demonstrate that the type series actually comprises two sets of specimens, and that examination of specimens from only one set or the other was responsible for some confusion surrounding these vouchers. Owing to the inconsistent naming and application of terms for some key characters (e.g., groove, sulcus, pit, hollow, depression) used in the diagnoses of Cyrtodactylus species, a set of novel and useful definitions was proposed. A comparative table for the bent-toad geckos of the Sunda Islands and Sulawesi was provided for the first time (paper 4). Cyrtodactylus throughout the Lesser Sundas, the Moluccas, and Sulawesi will be further investigated in future studies. Several museum vouchers will be described as new species.
The discovery of snakes of the genus Cylindrophis in Timor-Leste led to an investigation of the taxon C. ruffus, which is widely distributed in Maritime Southeast Asia. A new species of Cylindrophis, originally catalogued as C. ruffus in the herpetological collections of the Naturalis Biodiversity Center, Leiden, The Netherlands and the Naturhistorisches Museum Wien, Austria, was described from Grabag, Purworejo Regency, Jawa Tengah Province, Java, Indonesia. The new species can be distinguished from all congeners by several, distinct morphological features. A detailed account of the tangled taxonomic history of the similar and only putatively wide-ranging C. ruffus was provided, Scytale scheuchzeri (name referring to a colubroid taxon) was removed from the synonymy of C. ruffus, C. rufa var. javanica (a taxon originally described from Borneo) was listed as species inquirenda, and the recently described C. mirzae was synonymized with C. ruffus. Evidence was provided that the type locality of C. ruffus is Java. The discovery of C. subocularis and the bent-toed gecko Cyrtodacytlus klakahensis on Java highlights how little we know about the diversity of an island, on which herpetological research in Indonesia began two centuries ago (paper 6). The systematic relationships within Cylindrophis are being investigated in an ongoing study utilizing both molecular and morphological methods.
Based on specimens discovered in the collection of The Natural History Museum, London, UK, a new distribution record for the skink Sphenomorphus oligolepis was made for Seram Island, Maluku Province, Indonesia. The find constituted the westernmost record for this species and extended the distribution of this Papuan lizard well into Wallacea (paper 7).
The Asian toad, Duttaphrynus melanostictus, which was recently introduced to Madagascar (paper 8), is the main research focus of chapter 6. During field work in Timor-Leste, an Asian toad that had consumed a brahminy blindsnake, Indotyphlops braminus, was discovered. This indicated that indiscriminate foraging by this recently introduced toad species could endanger small vertebrates (paper 9). Timor shows an exceptionally high level of endemism in a wide range of faunal groups, and concerns that D. melanostictus may have a negative impact on this diversity, including vertebrates, through direct predation, had been raised by scientists. To evaluate the potential impact the feeding by D. melanostictus might have on the local fauna, gut contents of > 80 preserved toad specimens from five habitat types in Timor-Leste were examined and almost 6000 prey items identified. All prey items were invertebrates, with small eusocial insects comprising the major component of the diet. The wide prey spectrum demonstrated that D. melanostictus is a generalist invertebrate feeder. Although the Asian toad seems to not generally prey on vertebrates, vertebrate species that are morphologically similar to invertebrates in their overall appearance (worm-like gestalt) may be consumed. Data on intestinal parasites occuring in D. melanostictus were presented alongside the food spectrum analysis (paper 11).
Whereas information on the diet and internal parasites of anurans based on internal examinations have been published by numerous researchers, details of the incision method used to open the abdominal cavity of preserved specimens are rarely explained. An optimal incision into the pleuroperitoneal cavity of liquid-preserved anuran specimens to gain access to and permit easy removal of parts of the digestive tract in preparation for food spectrum analyses was formally proposed. This U-shaped cut is easy to perform and teach, and it has already been adopted in lab manuals. It provides better access to the pleuroperitoneal cavity than a small ventrolateral incision, and is less destructive than the classic textbook medial “double T-incision” routinely listed in dissection protocols. This new method may encourage other researchers to use preserved anurans for the purpose of food spectrum analyses and other examinations of internal morphology (paper 10).
An instance of captive breeding in a species of Timorese night skink (genus Eremiascincus) was reported, and the taxon demonstrated to be viviparous. A summary of information pertaining to the reproductive biology of other members of the genus Eremiascincus was provided (paper 12). Increased knowledge on the reproductive biology of Eremiascincus taxa will contribute to revisions of the group carried out by morphological and molecular analyses.
The type of the skink Anomalopus leuckartii was rediscovered in the herpetological collection of the Museum für Tierkunde, Dresden, Germany, together with other specimens from the original collection of Karl Georg Friedrich Rudolf Leuckart, who was one of zoology’s leading scientists during the second half of the 19th century and the founder of modern parasitology. This rediscovery serves as an excellent example to highlight the importance of maintaining natural history collections, not merely as static archives but rather as valuable dynamic and lively databases. This, in combination with optimal taxonomic expertise as a bedrock, guarantees an environment, in which new discoveries, like the ones presented in this dissertation, are actively promoted, thereby inevitably advancing modern biodiversity research (paper 13).
In a general conclusions section (chapter 8), the effects resulting from the combination and coordination of field work and collection-based studies are elaborated and illustrated in a diagram. The value of the studies presented in this thesis is primarily derived from specific interactions, synergistic effects, and an iterative process that connects them. Finally, the benefit for decision-makers dealing with conservation and species management is assessed.|
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