To investigate the breeding habitat preference of black flies, a comprehensive black fly survey was conducted for the first time in Peninsular Malaysia. Preimaginal black flies (pupae and larvae) were collected manually from 180 stream points encompassing northern, southern, central and east coast of the Peninsular Malaysia. A total of 47 black fly species were recorded in this study. The predominant species were Simulium trangense (36.7%) and Simulium angulistylum (33.3%). Relatively common species were Simulium cheongi (29.4%), Simulium tani (25.6%), Simulium nobile (16.2%), Simulium sheilae (14.5%) and Simulium bishopi (10.6%). Principal Component Analysis (PCA) of all stream variables revealed four PCs that accounted for 69.3% of the total intersite variance. Regression analysis revealed that high species richness is associated with larger, deeper, faster and higher discharge streams with larger streambed particles, more riparian vegetation and low pH (F=22.7, d.f.=1, 173; P<0.001). Relationship between species occurrence of seven common species (present in >10% of the sampling sites) was assessed. Forward logistic regression analysis indicated that four species were significantly related to the stream variables. S. nobile and S. tani prefer large, fast flowing streams with higher pH, large streambed particles and riparian trees. S. bishopi was commonly found at high elevation with cooler stream, low conductivity, higher conductivity and more riparian trees. In contrast, S. sheilae was negatively correlated with PC-2, thus, this species commonly found at low elevation, warmer stream with low conductivity and less riparian trees. The results of this study are consistent with previous studies from other geographic regions, which indicated that both physical and chemical stream conditions are the key factors for black fly ecology.
This is the first study on the seasonal biodiversity of black flies and evaluation of ecological factors influencing their distribution at Doi Pha Hom Pok National Park, northern Thailand. Larvae were collected from six fixed-stream sites in relation to altitude gradients from May 2011 to April 2013. The water temperature, water pH, conductivity, total dissolved solids (TDS), salt, water velocity, stream width and depth, streambed particle sizes, riparian vegetation, and canopy cover were recorded from each site. Monthly collections from the six sites yielded 5475 last-instar larvae, belonging to 29 black fly species. The most frequently found species from all sites were Simulium asakoae (100%) followed by Simulium yuphae (83.3%), and Simulium chiangdaoense, Simulium gombakense, Simulium phahompokense, Simulium fruticosum, Simulium maeaiense and Simulium fenestratum (66.6%). Of the 5475 last-instar larvae, S. maeaiense (19.3%), S. chiangdaoense (15.8%) and S. asakoae (14.8%), were the three most abundant species. The Shannon diversity index (H) at the six sites with different altitudes of 2100m, 2000m, 1500m, 1400m, 700m, and 500m above mean sea level, were 2.042, 1.832, 2.158, 2.123, 1.821 and 1.822, respectively. The Shannon index and number of taxa in the cold season were higher than those in the rainy and hot seasons. Principal component analysis (PCA) indicated that at least three principal components have eigen values >1.0 and accounted for 93.5% of the total variability of ecological factors among sampling sites. The Canonical correspondence analyses (CCA) showed that most species had a trend towards altitude, canopy cover, riparian vegetation and water velocity.
A new species of black fly, Simulium (Simulium) luculentum, is described from specimens collected in Thailand, and is assigned to the Simulium variegatum species-group of the subgenus Simulium Latreille. This new species is distinguished from most members of this species group in the female by the mid femur and tibia entirely yellowish; and in the pupa by the gill with six filaments, which are somewhat inflated basally. This species represents the fifth member of the S. variegatum species-group recorded from Thailand.
A recently described species of black fly, Simulium wayani Takaoka and Chen, from the island of Timor was chromosomally mapped to provide insights into its evolutionary and biogeographic history. The morphologically based species status of S. wayani is supported by a suite of fixed chromosomal rearrangements and unique sex chromosomes derived primarily from a large pool of polymorphisms in the S. ornatipes complex in Australia. The banding patterns of its polytene chromosomes indicate that S. wayani is closely related to a pair of homosequential cryptic species (S. norfolkense Dumbleton and S. ornatipes cytoform A2) in the S. ornatipes Skuse complex on mainland Australia; all three species uniquely share the same amplified band in their chromosomal complement. The low level of polymorphism and heterozygosity in S. wayani, relative to Australian populations of the S. ornatipes complex, suggests few colonization events from the larger land mass.
Black flies (Simuliidae) are important biting insects and vectors of diseases agents of humans and livestock. Thus, understanding the taxonomy and biodiversity of these insects is crucial for control and management of these diseases. In this study, we used mitochondrial cytochrome c oxidase I sequences to examine genetic diversity of three human-biting and possible vector black fly taxa; the Simulium asakoae species-complex, S. chamlongi and S. nigrogilvum. High levels of genetic diversity (>3.5% intraspecific genetic divergence) were found in all three taxa. Phylogenetic analyses indicated that the S. asakoae complex can be divided into seven groups with the largest group consisting of specimens from Thailand, Malaysia and Myanmar. This group most likely represents true S. asakoae. The remaining haplotypes formed groups with conspecific haplotypes or with other closely related species. Among these groups, one including S. monglaense and another including S. myanmarense suggest that certain specimens identified as S. asakoae most likely belong to those species. Therefore, they constitute new locality records for Thailand and also represent new records of anthropophily. Members of S. chamlongi are not monophyletic as its clade also included S. hackeri. A median joining network revealed strong geographic associations of the haplotypes of S. nigrogilvum suggesting limitation of gene flow. Because this species occurs mainly in high elevation habitats, low land areas could present a barrier to gene flow.
Three new species of black flies from Thailand, Simulium wangkwaiense, S. tadtonense and S. maeklongkeense, are described based on their adults, pupal exuviae and cocoons. All three new species are assigned to the Simulium (Simulium) striatum species-group, bringing its total number in Thailand to seven. Simulium wangkwaiense sp. nov. is the species formerly called S. quinquestriatum in Thailand. Certain male and pupal morphological characteristics are shown to separate all seven Thai species of this species-group. All of the three new species have been analyzed genetically for their phylogenetic relationships, with three known related species (except for S. thailandicum), by using the fast-evolving nuclear big zinc finger (BZF) gene.
A new black fly species, Simulium (Gomphostilbia) pangsidaense, is described on the basis of adult female, male, pupal exuviae and mature larvae from Pang Sida National Park, Sa Kaew Province, Eastern Thailand. This new species is placed in the Simulium ceylonicum species-group. It is distinguished from three Thai members of the S. ceylonicum species-group by the following characteristics: from S. (G.) curtatum Jitklang et al. and S. (G.) sheilae Takaoka & Davies by the wide pupal terminal hooks (triangular terminal hooks in the latter two species), and from S. (G.) sheilae and S. (G.) trangense Jitklang et al. by the number of male upper-eye facets in 13 vertical columns and 14 or 15 horizontal rows (10 or 11 vertical columns and 12 or 13 horizontal rows in the latter two species). This is the fourth member of the S. ceylonicum species-group recorded from Thailand.
A new black fly species, Simulium (Gomphostilbia) kiewlomense, is described from females, males, pupae and mature larvae in Thailand. This new species is placed in the S. asakoae species-group and is characterized by having a combination of the elongate female sensory vesicle, widened male hind basitarsus, which is much wider than the hind femur, small pupal terminal hooks, and light greenish larval abdominal segments 1-3. Taxonomic notes are given to separate this new species from other related species. A DNA analysis using the COI gene shows that this new species has two genoforms with 1.21% difference. This is the 28th species of the S. asakoae species-group in Thailand, strengthening the evidence for high species diversity of this species-group.
Although the microbiome of blood-feeding insects serves an integral role in host physiology, both beneficial and pathogenic, little is known of the microbial community of black flies. An investigation, therefore, was undertaken to identify culturable bacteria from one of Malaysia's most common black flies, Simulium tani Takaoka and Davies, using 16S rDNA sequencing, and then evaluate the isolates for antibiotic resistance and virulence genes. A total of 20 isolates representing 11 bacterial species in four genera were found. Five isolates showed β-hemolysis on Columbia agar, and virulence genes were found in three of these isolates. Some degree of resistance to six of the 12 tested antibiotics was found among the isolates. The baseline data from this study suggest rich opportunities for comparative studies exploring the diversity and roles of the microbiome of S. tani and other Southeast Asian black flies.
Most female black flies in the genus Simulium are blood-sucking flies and they can cause various parasitic diseases in human and animal. A total of 94 species of black flies have been reported in Malaysia, however, their biting behavior and role as vector of infectious agents remain understudied. To fill in this knowledge gap, we attempted to survey adult black flies from field populations in Peninsular Malaysia. In a survey carried out in 2017 at Tasik Kenyir, Terengganu, three females were caught while attracted and landed on human skin. Further morphological and molecular analyses showed that the specimens were identical to Simulium (Gomphostilbia) aziruni Takaoka, Hashim & Chen of the Simulium gombakense species-group. This is the first report on a black fly species attracted to human in Malaysia which serves as a steppingstone towards in-depth studies for black flies in this region.
The simuliid fauna of the Oriental Region is reviewed in comparison with those in five other zoogeographical regions. It is relatively young, represented by only one genus Simulium, which is regarded as the most specialized among 26 genera of the family Simuliidae. The Oriental Region has the second largest simuliid fauna with 524 species or 23.8% of the world total of 2204 extant species. This species richness is associated with a high speciation index (15.4), reflected especially by the high speciation rates of two dominant subgenera Gomphostilbia and Simulium although the number of lineages in the Oriental Region is moderate (34 or 20.6% of the total 165). The Oriental fauna has relationships with all other zoogeographical regions at the lineage level, having the highest affinity index (31.9) with the Palearctic Region. It is inferred that eight of 10 Oriental subgenera moved during the ice ages from the Palaearctic to the Oriental Regions; the subgenus Gomphostilbia evolved into 11 species-groups and underwent species radiation in the Oriental Region. On the other hand, two other subgenera, Nevermannia and Simulium, moved southward during the ice ages after evolving into species-groups. In the post-ice ages, most lineages retreated northward, with different portions of species left in the Oriental Region, although some lineages failed to retreat and survived as relict lineages in the Oriental Region.
The female and larva of Simulium (Gomphostilbia) udomi Takaoka & Choochote from Thailand are described for the first time. The female of this species is similar to those of S. (G.) asakoae Takaoka & Davies from Peninsular Malaysia, Thailand, Hong Kong and Vietnam, and S. (G.) chiangdaoense Takaoka & Srisuka from Thailand. The larva of this species is similar to S. (G.) curtatum Jitklang et al. and S. (G.) nr. asakoae 2 from Thailand in having a medium-long postgenal cleft. Taxonomic notes are given to separate this species from these related species. The COI gene sequence of S. (G.) udomi is compared with those of eight species of the S. asakoae species-group and three species of the S. ceylonicum species-group. This species is transferred from the S. ceylonicum species-group to the S. asakoae species-group based on the adult female and male morphological characters, comparisons of the genetic distances and phylogenetic relationships inferred from the COI gene sequences.
Simulium (Simulium) hackeri Edwards, 1928 of the Simulium variegatum species-group from Malaysia was described initially based on the female specimen from Cameron Highlands, Pahang. In the present study, the pupa and larva of this species are described for the first time. Their morphological characters resemble those of the Simulium variegatum species-group by having six gill filaments per side, abdomen with dorsal spine-combs at least on segments 7 and 8, cocoon with wall-pocket shaped and with or without an anterodorsal projection. Postgenal cleft of the larva medium-sized, rarely small, ventral papillae small or absent. The DNA barcode of this species is also reported herein.
Larvae and adults reared from pupae of Simulium (Gomphostilbia) gombakense Takaoka & Davies from eight streams in five provinces of Thailand were genetically analyzed by using cytochrome c oxidase subunit 1 sequences. The material was composed of four lineages, of which lineages 2, 3 and 4 are genetically closely related to one another, but more distantly related to lineage 1, which is equivalent to typical S. (G.) gombakense from Peninsular Malaysia. Lineages 2, 3 and 4, which are morphologically indistinguishable, are designated as genoforms A, B and C within a species complex of S. (G.) paiense sp. nov., which is described based on specimens of lineage 2 (=genoform A). Simulium (G.) paiense sp. nov. is similar to S. (G.) gombakense from Peninsular Malaysia but appears to be barely distinguished by the relative length of the female fore basitarsus. Simulium (G.) thuathienense Takaoka & Sofian-Azirun is newly recorded from Thailand and its male is described for the first time. The female of S. (G.) gombakense is briefly described based on females reared from pupae collected from Peninsular Malaysia.
Two new species of Simulium (Gomphostilbia), S. (G.) myanmarense and S. (G.) monglaense, are described from females, males, pupae and larvae from Myanmar. The two new species are placed in the S. asakoae species-group, and are similar to each other in the female and male but distinguished in the pupa by the presence or absence of an anterodorsal projection of the cocoon, and in the larva by a unique pattern of colored markings on the abdomen. Taxonomic notes are given to separate these species from related species. The COI gene sequences of both species are compared with those of eight species of the S. asakoae species-group and three species of the S. ceylonicum species-group. Both new species are most closely related to each other, further supporting their morphological classification in the S. asakoae species-group.
A black fly species of the Simulium feuerborni species-group of Simulium (Nevermannia) from Cameron Highland, Peninsular Malaysia, previously regarded as S. feuerborni Edwards, originally described from East Java, is described as Simulium pairoti sp. nov. based on complete life stages. High intraspecific variations in the arrangement of the six pupal gill filaments, length of the stalk of the ventral paired filaments, and length of the anterodorsal projection of the cocoon, are noted in this species. This new species is readily distinguished from its congeners by having the characters of male genitalia with simple lamellate ventral plate, short inwardly-twisted styles, several parameral hooks, and a simple narrow median sclerite. Morphological data reported herein plus the chromosomal and molecular data presented elsewhere support S. pairoti as a novel pseudocryptic species.
In recent decades, the numbers of cryptic taxa have increased significantly with current progress in DNA barcoding, yet, most of these cryptic taxa have not been formally named and recognized as valid species. To address this issue, we provide a guide for applying the procedure of describing new cryptic species in the family Simuliidae. Simulium (Simulium) vanluni from Pahang, Peninsular Malaysia, previously treated as S. nobile De Meijere, is described as a new species by using an integrated morpho-taxonomical and genetic approach. This new species is morphologically identical to S. nobile from Java and S. kiuliense Smart & Clifford from Borneo, but their distinctiveness is supported by an expanded multigene phylogeny analysis.
Surveys of pupae and larvae of black flies were carried out in Bali, Lombok, Sumbawa and Flores in the Lesser Sunda Archipelago, Indonesia, where 10 species were known. A total of 14 simuliid species including four new species and five new records of the genus Simulium were collected, bringing the number of species from the Lesser Sunda Archipelago to 19. They are classified into four subgenera: two in Nevermannia, nine in Gomphostilbia, seven in Simulium and one in Wallacellum. One of four new species, Simulium (Simulium) baliense, is described based on females, males, pupae and larvae from Bali and Lombok. This new species, which is placed in the Simulium striatum species-group of the subgenus Simulium, is closely related to S. (S.) argyrocinctum De Meijere from Java and Sumatra, but it is distinguished from the latter species by the smaller number of the male enlarged upper-eye facets and larval abdomen lacking dorsal pairs of conical protuberances. The distribution record of S. (S.) upikae Takaoka & Davies from Flores is corrected as that of S. (S.) eximium De Meijere. Some aberrant characters of the pupal gill filaments of S. (G.) atratum De Meijere, S. (G.) floresense Takaoka, Hadi & Sigit and S. (G.) sunapii Takaoka, Sofian-Azirun & Suana are illustrated. Characteristics of the fauna of black flies in this archipelago are briefly noted. Keys to all 19 species are provided for females, males, pupae and larvae.
Simulium pumatense sp. nov. is described from Vietnam, and is placed in the Simulium feuerborni species-group of the subgenus Simulium (Nevermannia) Enderlein. Its morphological characteristics include the relatively smaller numbers of the following three numerical features: inner teeth of the female mandible (15-18), minute conical processes (16) on the female cibarium, and male upper-eye facets (in 15 vertical columns and 16 horizontal rows). Keys are constructed to distinguish this species from four species of the same group in Vietnam. Our molecular analysis of the DNA barcoding COI gene shows that this species is most closely related to cytoform A of the S. feuerborni complex from Thailand.
Blackflies (Diptera: Simuliidae) are ecologically and medically important insects but they have been understudied in Malaysia. Accordingly, a study on the temporal variation in diversity and community structure of preimaginal blackflies was conducted for the first time in Malaysia. A total of 865 preimaginal blackflies were collected in 120 samplings from five streams across three monsoon seasons from February 2018 until January 2019. Ten species were recorded and most frequently collected species were Simulium cheongi, Simulium vanluni and Simulium jeffreyi. Relatively common species were Simulium roslihashimi, Simulium tani complex and Simulium trangense. No significant changes of rainfall was observed between three monsoon seasons as well as the seasons with species and physiochemical parameters except acidity (pH) (P 20%) indicated that S. vanluni and S. jeffreyi were commonly associated with wider, deeper and fast-flowing streams with low conductivity and larger streambed particle. In contrast, S. cheongi was associated with smaller, slower and small streambed particle. This first extensive bimonthly study has uncovered the species community structure as well as the changes of stream physicochemical parameters over time although they were not greatly and significantly influenced by the monsoon seasons. Species distribution, richness and abundance, however, were highly determined by the stream width, depth and velocity, therefore, were vital in shaping diversity and community structure of preimaginal blackflies.