Cranston, P. S., Ang, Y. C., Heyzer, A., Lim, R. B. H., Wong, W. H. (2013): The Nuisance Midges (... more Cranston, P. S., Ang, Y. C., Heyzer, A., Lim, R. B. H., Wong, W. H. (2013): The Nuisance Midges (Diptera: Chironomidae) Of Singapore'S Pandan And Bedok Reservoirs. Raffles Bulletin of Zoology 61 (2): 779-793
The two species of chironomid midges that are known to be involved in mass swarming on the shores... more The two species of chironomid midges that are known to be involved in mass swarming on the shores of Singapore's Pandan and Bedok reservoirs are described or redescribed. All life stages are illustrated to allow identifi cation. Polypedilum nubifer (Skuse), the predominant nuisance midge of Pandan reservoir, is globally known as a coloniser of new and unstable aquatic habitats. Its biology and methods of control are understood. In contrast, Tanytarsus oscillans Johannsen is the predominant nuisance midge at Bedok reservoir. This species is restricted to Asia from India to southern Japan and its immature stages were unknown previously. Its nuisance status (restricted to Bedok Reservoir, Singapore) is of recent origin. Means of separating these species from similar chironomid species in the region are provided. We conclude with some observations on the chironomid fauna of standing waters in Singapore.
Male abdomen appendages are a novel trait found within Sepsidae (Diptera). Here we demonstrate th... more Male abdomen appendages are a novel trait found within Sepsidae (Diptera). Here we demonstrate that they are likely to have evolved once, were lost three times, and then secondarily gained in one lineage. The developmental basis of these appendages was investigated by counting the number of histoblast cells in each abdominal segment in four species: two that represented the initial instance of appendage evolution, one that has secondarily gained appendages, and one species that did not have appendages.
R. (2010). From 'cryptic species' to integrative taxonomy: an iterative process involving DNA seq... more R. (2010). From 'cryptic species' to integrative taxonomy: an iterative process involving DNA sequences, morphology, and behaviour leads to the resurrection of Sepsis pyrrhosoma (Sepsidae: Diptera). -Zoologica Scripta, 39, 51-61. The increased availability of DNA sequences has led to a surge of 'cryptic species' in the literature. These units are usually proposed based on finding genetically distinct lineages within species that were initially defined based on morphological characters. However, few authors attempt to confirm whether these 'cryptic' units are species and even fewer authors are explicit about which species concept is applied. Here, we use an example from Sepsidae (Diptera) to demonstrate how cryptic species can be validated by an iterative process involving several data sources and an evaluation of the data under different species concepts. A phylogeographic analysis based on 50 specimens for five species of the flavimana group revealed deep mitochondrial splits within Sepsis flavimana which was suggestive of a cryptic species. We resolve the initial conflict between DNA sequences and morphology by adding new morphological data as well as behavioural evidence and tests for reproductive isolation. One cryptic species is confirmed and Sepsis pyrrhosoma, a former synonym of S. flavimana, is here shown to be a valid species under most species concepts. We can thus document that the same data can lead to similar conclusions under conflicting concepts once different kinds of data are integrated.
The males of almost all sepsid species have strongly modified forelegs that are used to clamp the... more The males of almost all sepsid species have strongly modified forelegs that are used to clamp the female's wingbase during mounting. Here, we describe a new species in the genus Perochaeta whose males have unmodified forelegs. We use DNA sequence data for ten genes to reconstruct the position of Perochaeta on the phylogenetic tree for Sepsidae, and reveal that the lack of foreleg armature in Perochaeta dikowi sp.n. is secondary. Through the study of the mating behaviour of the new species, we demonstrate that the loss of armature is correlated with a new mounting technique during which the males of P. dikowi do not use the foreleg to clamp the female's wingbase. Instead, the male approaches the female from behind and bends his abdomen forwards in order to establish genital contact. Our study shows how data from morphology, phylogenetics, and behavioural biology can complement each other to yield a deeper understanding of how changes in morphology and behaviour are correlated.
Cranston, P. S., Ang, Y. C., Heyzer, A., Lim, R. B. H., Wong, W. H. (2013): The Nuisance Midges (... more Cranston, P. S., Ang, Y. C., Heyzer, A., Lim, R. B. H., Wong, W. H. (2013): The Nuisance Midges (Diptera: Chironomidae) Of Singapore'S Pandan And Bedok Reservoirs. Raffles Bulletin of Zoology 61 (2): 779-793
The two species of chironomid midges that are known to be involved in mass swarming on the shores... more The two species of chironomid midges that are known to be involved in mass swarming on the shores of Singapore's Pandan and Bedok reservoirs are described or redescribed. All life stages are illustrated to allow identifi cation. Polypedilum nubifer (Skuse), the predominant nuisance midge of Pandan reservoir, is globally known as a coloniser of new and unstable aquatic habitats. Its biology and methods of control are understood. In contrast, Tanytarsus oscillans Johannsen is the predominant nuisance midge at Bedok reservoir. This species is restricted to Asia from India to southern Japan and its immature stages were unknown previously. Its nuisance status (restricted to Bedok Reservoir, Singapore) is of recent origin. Means of separating these species from similar chironomid species in the region are provided. We conclude with some observations on the chironomid fauna of standing waters in Singapore.
Male abdomen appendages are a novel trait found within Sepsidae (Diptera). Here we demonstrate th... more Male abdomen appendages are a novel trait found within Sepsidae (Diptera). Here we demonstrate that they are likely to have evolved once, were lost three times, and then secondarily gained in one lineage. The developmental basis of these appendages was investigated by counting the number of histoblast cells in each abdominal segment in four species: two that represented the initial instance of appendage evolution, one that has secondarily gained appendages, and one species that did not have appendages.
R. (2010). From 'cryptic species' to integrative taxonomy: an iterative process involving DNA seq... more R. (2010). From 'cryptic species' to integrative taxonomy: an iterative process involving DNA sequences, morphology, and behaviour leads to the resurrection of Sepsis pyrrhosoma (Sepsidae: Diptera). -Zoologica Scripta, 39, 51-61. The increased availability of DNA sequences has led to a surge of 'cryptic species' in the literature. These units are usually proposed based on finding genetically distinct lineages within species that were initially defined based on morphological characters. However, few authors attempt to confirm whether these 'cryptic' units are species and even fewer authors are explicit about which species concept is applied. Here, we use an example from Sepsidae (Diptera) to demonstrate how cryptic species can be validated by an iterative process involving several data sources and an evaluation of the data under different species concepts. A phylogeographic analysis based on 50 specimens for five species of the flavimana group revealed deep mitochondrial splits within Sepsis flavimana which was suggestive of a cryptic species. We resolve the initial conflict between DNA sequences and morphology by adding new morphological data as well as behavioural evidence and tests for reproductive isolation. One cryptic species is confirmed and Sepsis pyrrhosoma, a former synonym of S. flavimana, is here shown to be a valid species under most species concepts. We can thus document that the same data can lead to similar conclusions under conflicting concepts once different kinds of data are integrated.
The males of almost all sepsid species have strongly modified forelegs that are used to clamp the... more The males of almost all sepsid species have strongly modified forelegs that are used to clamp the female's wingbase during mounting. Here, we describe a new species in the genus Perochaeta whose males have unmodified forelegs. We use DNA sequence data for ten genes to reconstruct the position of Perochaeta on the phylogenetic tree for Sepsidae, and reveal that the lack of foreleg armature in Perochaeta dikowi sp.n. is secondary. Through the study of the mating behaviour of the new species, we demonstrate that the loss of armature is correlated with a new mounting technique during which the males of P. dikowi do not use the foreleg to clamp the female's wingbase. Instead, the male approaches the female from behind and bends his abdomen forwards in order to establish genital contact. Our study shows how data from morphology, phylogenetics, and behavioural biology can complement each other to yield a deeper understanding of how changes in morphology and behaviour are correlated.
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