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A new black fly species of Simulium (Simulium) (Diptera: Simuliidae) from Taiwan

Takaoka H, Huang YT

Zootaxa, 2018 May 22;4422(1):141-150.
PMID: 30313517 DOI: 10.11646/zootaxa.4422.1.9

A new black fly species, Simulium taichungense, is described on the basis of one female, one male and two pupal exuviae from Taiwan. This new species is placed in the S. crocinum species-group of Simulium (Simulium) (Diptera: Simuliidae). It is characterized by the pupal gill with six unpigmented short filaments and pupal abdomen with distinct spine-combs on the dorsal surface of segments 7-9, by which it is easily distinguished from most species in the S. crocinum species-group including two species from Taiwan: Simulium serenum Huang Takaoka and S. ufengense Takaoka. It is the third species of the S. crocinum species-group from Taiwan. In addition, the male of S. serenum is described for the first time, and intraspecific variations in a few features of the male of S. chungi Takaoka Huang of the S. chungi species-group are noted.
Two new black fly species of the Simulium ( Simulium) rufibasis subgroup (Diptera: Simuliidae) from Taiwan

Takaoka H, Low VL, Huang YT, Fukuda M, Ya'cob Z

Trop Biomed, 2021 Sep 01;38(3):403-412.
PMID: 34608114 DOI: 10.47665/tb.38.3.081

Simulium ( Simulium) rufibasis Brunetti originally described from India was once considered a geographic generalist widely distributed in the Oriental Region. In this study, the species previously regarded as S. (S.) rufibasis in Taiwan was morphologically re-evaluated and found to be distinguished in the male and pupa from true S. (S.) rufibasis from India. This new species is described as S. ( S.) hehuanense sp. nov. based on a female, a male and their pupal exuviae in Taiwan. This new species is placed in the S. rufibasis subgroup of the S. tuberosum species-group, and is similar to S. (S.) yamatoense Takaoka, Adler & Fukuda from Japan and Korea, but it is barely distinguished by the slenderer forebasitarsi of the female and male. Another new, related species, S. (S.) xiulinense sp. nov., is described based on a male and its pupal exuviae. This new species is distinguished from S. (S.) hehuanense sp. nov. by the number of male upper-eye (large) facets in 20 or 21 vertical columns and 22 horizontal rows (19 vertical columns and 19 horizontal rows in the latter species), and presence of a pair of dorsolateral shiny spots on male abdominal segment 5 (absence in the latter species). Both new species inhabit streams at high elevations (ca, 2,600 m). They differ from S. (S.) sp. (probably S. (S.) arisanum Shiraki) from Taiwan, of the same subgroup, which breeds in streams at low elevations (433-685 m), by the pupal head and thorax covered with tubercles (bare in the latter species).
Two new black fly species of the Simulium (Gomphostilbia) asakoae species-group (Diptera: Simuliidae) from Taiwan

Takaoka H, Low VL, Huang YT, Fukuda M, Ya'cob Z

Acta Trop, 2021 Oct;222:106023.
PMID: 34161814 DOI: 10.1016/j.actatropica.2021.106023

Two new black fly species, Simulium (Gomphostilbia) kaohsiungense and S. (G.) shoufengense, are described from females, males and pupae in Taiwan. These new species are placed in the S. asakoae species-group. Simulium (G.) kaohsiungense sp. nov. is characterized by a combination of the elongate female sensory vesicle, male upper-eye (large) facets in 15 vertical columns and 15 or 16 horizontal rows, male hind basitarsus 1.02-1.15 times the width of the hind femur, and widened pupal terminal hooks. These characteristics distinguish this new species from most species of the S. asakoae species-group. Simulium (G.) shoufengense sp. nov. is similar in the female and male to S. (G.) asakoae Takaoka & Davies originally described from Peninsular Malaysia but is distinguished from the latter species in the pupa by the combined length of the primary and secondary stalks of the dorsal triplet of gill filaments as long as or longer than the common basal stalk of the gill, and dorsum of abdominal segments 1 and 2 not darkened. The species previously regarded in Taiwan as S. (G.) metatarsale Brunetti, originally described from India, is morphologically and molecularly identified as S. (G.) asakoae.
Fulltext Macrogenomic evidence for the origin of the black fly Simulium suzukii (Diptera: Simuliidae) on Okinawa Island, Japan

Adler PH, Huang YT, Reeves WK, Kim SK, Otsuka Y, Takaoka H

PLoS One, 2013;8(8):e70765.
PMID: 23951001 DOI: 10.1371/journal.pone.0070765

To determine the geographic origin of the black fly Simulium suzukii on Okinawa Island, Japan, macrogenomic profiles derived from its polytene chromosomes were compared with those of mainland and other insular populations of S. suzukii and of the isomorphic Simulium tani species complex. The Okinawan population is a chromosomally unique cytoform, designated 'D,' which is essentially monomorphic and differs by about 27 fixed rearrangements from the chromosomal standard sequence for the subgenus Simulium and by two fixed differences from its nearest known relative, representing the type of S. suzukii, on the main islands of Japan. Chromosomal band sequences revealed two additional, sympatric cytoforms of S. suzukii, designated 'A' and 'B,' each with species status, in Korea, and a third cytoform, designated 'C,' on Hokkaido, Japan. A new cytoform, 'K,' of S. tani from Malaysia, representing the type of S. tani, is more closely related to cytoforms in Thailand, as are populations from Taiwan previously treated as S. suzukii but more closely aligned with S. tani and newly recognized as cytoform 'L' of the latter nominal species. Rooting of chromosomal band sequences by outgroup comparisons allowed directionality of chromosomal rearrangements to be established, enabling phylogenetic inference of cytoforms. Of 41 macrogenomic rearrangements discovered in the five new cytoforms, four provide evidence for a stepwise origin of the Okinawan population from populations characteristic of the main islands of Japan. The macrogenomic approach applied to black flies on Okinawa Island illustrates its potential utility in defining source areas for other species of flies including those that might pose medical and veterinary risks.
Morphological and genetic revision of cytoform 'L' of the Simulium (Simulium) tani complex from Taiwan, and cytoform 'D' of the S. (S.) suzukii complex (Diptera: Simuliidae) from the Nansei Islands, Japan

Takaoka H, Otsuka Y, Low VL, Adler PH, Fukuda M, Huang YT, et al.

Acta Trop, 2021 Dec;224:106124.
PMID: 34508715 DOI: 10.1016/j.actatropica.2021.106124

The species status of two cytoforms of two species complexes in the Simulium (Simulium) tuberosum species-group, which are almost indistinguishable in the pupal stage, was morphologically and genetically evaluated. Cytoform 'L' of the S. (S.) tani Takaoka & Davies complex, previously recognized as S. (S.) suzukii Rubtsov in Taiwan, is described as a new species, S. (S.) jianshiense. It is morphologically distinguishable as adults from two members of the S. (S.) suzukii complex: cytoform 'C' from Hokkaido, selected to represent the type of S. (S.) suzukii sensu stricto, and cytoform 'D' from Okinawa Island and, based on our chromosomal analysis, also from Amami Island. This new species is genetically separated from both cytoforms of the S. (S.) suzukii complex with a genetic distance of 5.31-6.67%. Cytoform 'D' is distinguished from cytoform 'C' by the color of the male forecoxa and relative length of the female sensory vesicle to the third maxillary palpomere. Accordingly, the name S. (S.) ryukyuense Ogata, once regarded as a synonym of S. (S.) suzukii, is revalidated and applied to cytoform 'D'. The genetic distance between S. (S.) ryukyuense and S. (S.) suzukii sensu stricto is 1.24-1.60%.
Descriptions of two new species of the Simulium (Simulium) striatum species-group (Diptera: Simuliidae) from Taiwan and Japan, and a revised description of S. (S.) quinquestriatum (Shiraki)

Takaoka H, Otsuka Y, Huang YT, Low VL, Fukuda M, Ya'cob Z

Acta Trop, 2021 Dec 25;227:106293.
PMID: 34958767 DOI: 10.1016/j.actatropica.2021.106293

Species in the Simulium (Simulium) striatum species-group (Diptera: Simuliidae) in Taiwan and Japan are morphologically reevaluated. Simulium (S.) yanpingense sp. nov. is described as the third member in this species-group from Taiwan and a revised description of S. (S.) quinquestriatum (Shiraki) is provided. The species previously regarded as S. (S.) quinquestriatum in Japan is described as a new species, S. (S.) tanegashimaense. Simulium (S.) yanpingense sp. nov. is similar to S. (S.) pingtungense Huang & Takaoka from Taiwan, in many characteristics including the haired basal portion of the female radius, dark leg color, and male scutum with brassy hairs, but it is distinguished from the latter species by the number of male upper-eye (large) facets, which are in 17 (rarely 18) vertical columns and 17 or 18 horizontal rows in this new species but in 19 vertical columns and 20 horizontal rows in S. (S.) pingtungense. Simulium (S.) tanegashimaense sp. nov. is similar to S. (S.) quinquestriatum originally described from Taiwan by having the male scutum with yellow fine hairs, but is distinguished from the latter species by the number of male upper-eye (large) facets, which are in 17 (rarely 16) vertical columns and 17 horizontal rows in this new species but in 19 or 20 vertical columns and 19 or 20 horizontal rows in S. (S.) quinquestriatum. The morphological differences between these two new species and their related species from India, Malaysia, Thailand and Vietnam are noted.
A New Species of the Simulium (Simulium) argentipes Species-Group (Diptera: Simuliidae) From Taiwan, and Its Phylogenetic Relationships With Four Related Species

Takaoka H, Low VL, Tan TK, Huang YT, Fukuda M, Ya'cob Z

J Med Entomol, 2018 06 28;55(4):884-892.
PMID: 29538704 DOI: 10.1093/jme/tjy028

A new black fly species, Simulium haiduanense Takaoka, Low & Huang (Diptera: Simuliidae), is described on the basis of females, males, pupae, and mature larvae from Taiwan. This new species is placed in the Simulium argentipes species-group of the subgenus Simulium (Diptera: Simuliidae) and is characterized by the yellowish female legs, ovipositor valves rounded apically and with its inner margin concave, claw with a small subbasal tooth, male style without a basal protuberance, pupal gill with eight filaments, corbicular cocoon, and larval abdomen lacking paired protuberances. It represents the first record of the S. argentipes species-group from Taiwan. Taxonomic notes are given to separate this new species from all eight species in the same species-group. The phylogenetic relationships of this new species with four related species are presented.
Fulltext Tests of conspecificity for allopatric vectors: Simulium nodosum and Simulium shirakii (Diptera: Simuliidae) in Asia

Low VL, Adler PH, Sofian-Azirun M, Srisuka W, Saeung A, Huang YT, et al.

Parasit Vectors, 2015 May 29;8:297.
PMID: 26022092 DOI: 10.1186/s13071-015-0911-5

BACKGROUND: Allopatric populations present challenges for biologists working with vectors. We suggest that conspecificity can be concluded in these cases when data from four character sets-chromosomal, ecological, molecular, and morphological-express variation no greater between the allopatric populations than between corresponding sympatric populations. We use this approach to test the conspecificity of Simulium nodosum Puri on the mainland of Southeast Asia and Simulium shirakii Kono & Takahasi in Taiwan. The validity of these two putative species has long been disputed given that they are morphologically indistinguishable.
FINDINGS: The mitochondria-encoded cytochrome c oxidase subunit I (COI), 12S rRNA, and 16S rRNA genes and the nuclear-encoded 28S rRNA gene support the conspecific status of S. nodosum from Myanmar, Thailand, and Vietnam and S. shirakii from Taiwan; 0 to 0.19 % genetic differences between the two taxa suggest intraspecific polymorphism. The banding patterns of the polytene chromosomes of the insular Taiwanese population of S. shirakii and mainland populations of S. nodosum are congruent. The overlapping ranges of habitat characteristics and hosts of S. nodosum and S. shirakii corroborate the chromosomal, molecular, and morphological data.
CONCLUSIONS: Four independent sources of evidence (chromosomes, DNA, ecology, and morphology) support the conspecificity of S. nodosum and S. shirakii. We, therefore, synonymize S. shirakii with S. nodosum. This study provides a guide for applying the procedure of testing conspecificity to other sets of allopatric vectors.
Fulltext Delineating taxonomic boundaries in the largest species complex of black flies (Simuliidae) in the Oriental Region

Low VL, Takaoka H, Pramual P, Adler PH, Ya'cob Z, Huang YT, et al.

Sci Rep, 2016 Feb 03;6:20346.
PMID: 26839292 DOI: 10.1038/srep20346

Perspicuous assessments of taxonomic boundaries and discovery of cryptic taxa are of paramount importance in interpreting ecological and evolutionary phenomena among black flies (Simuliidae) and combating associated vector-borne diseases. Simulium tani Takaoka & Davies is the largest and perhaps the most taxonomically challenging species complex of black flies in the Oriental Region. We use a DNA sequence-based method to delineate currently recognized chromosomal and morphological taxa in the S. tani complex on the Southeast Asian mainland and Taiwan, while elucidating their phylogenetic relationships. A molecular approach using multiple genes, coupled with morphological and chromosomal data, supported recognition of cytoform K and morphoform 'b' as valid species; indicated that S. xuandei, cytoform L, and morphoform 'a' contain possible cryptic species; and suggested that cytoform B is in the early stages of reproductive isolation whereas lineage sorting is incomplete in cytoforms A, C, and G.