Genetic relationships of three species of black flies (Diptera: Simuliidae) in Taiwan.

As an island about 150 km from the mainland, Taiwan would be expected to have endemic species. About 64 % of its 36 species of black flies are considered endemic, more than twice the level of endemicity that has been recorded for all insects on the island. To begin assessing the validity of the high level of endemism for the Simuliidae, we used giant chromosome banding patterns and cytochrome c oxidase I (COI) sequences, against a well-defined morphological backdrop, to evaluate three of Taiwan's black flies, Simulium chungi Takaoka & Huang, S. pingtungense Huang & Takaoka, and S. sakishimaense Takaoka. Molecular data revealed high similarity of populations of S. sakishimaense in Taiwan and at the type locality on Ishigaki Island, Japan, about 180 km to the east. Thus, populations referred to as S. sakishimaense in Taiwan are conspecific with typical S. sakishimaense in Japan, confirming their non-endemicity in Taiwan. Simulium sakishimaense might have reached Ishigaki by island hopping via Taiwan from the Chinese mainland. Chromosomes and the COI gene agree with morphology that S. sakishimaense is a member of the S. multistriatum species group although the chromosomal banding patterns do not indicate that it is distinct from S. fenestratum Edwards on the mainland. Although molecular sequences indicate S. sakishimaense is monophyletic, this taxon falls within the same Operational Taxonomic Unit as nine other members of the S. multistriatum group, including S. fenestratum. Simulium pingtungense, in agreement with morphology, is molecularly distinct from the 10 other analyzed members of the S. striatum species group, tentatively suggesting that it is endemic to Taiwan, pending analysis of samples from mainland China. Simulium chungi in Taiwan is chromosomally and molecularly unique, with larvae resembling those of S. saskishimaense. It is not, however, a member of either the S. multistriatum or S. striatum species groups. For now, the S. chungi species group remains a legitimate taxon consisting of two species. Strengthening the case for endemic taxa in Taiwan awaits analysis of key samples from the Chinese mainland.

Tiger prowling: Distribution modelling for northward-expanding Aedes albopictus (Diptera: Culicidae) in Japan.

The Asian tiger mosquito, Aedes albopictus, is a significant public health concern owing to its expanding habitat and vector competence. Disease outbreaks attributed to this species have been reported in areas under its invasion, and its northward expansion in Japan has caused concern because of the potential for dengue virus infection in newly populated areas. Accurate prediction of Ae. albopictus distribution is crucial to prevent the spread of the disease. However, limited studies have focused on the prediction of Ae. albopictus distribution in Japan. Herein, we used the random forest model, a machine learning approach, to predict the current and potential future habitat ranges of Ae. albopictus in Japan. The model revealed that these mosquitoes prefer urban areas over forests in Japan on the current map. Under predictions for the future, the species will expand its range to the surrounding areas and eventually reach many areas of northeastern Kanto, Tohoku District, and Hokkaido, with a few variations in different scenarios. However, the affected human population is predicted to decrease owing to the declining birth rate. Anthropogenic and climatic factors contribute to range expansion, and urban size and population have profound impacts. This prediction map can guide responses to the introduction of this species in new areas, advance the spatial knowledge of diseases vectored by it, and mitigate the possible disease burden. To our knowledge, this is the first distribution-modelling prediction for Ae. albopictus with a focus on Japan.

Independent distribution between tauopathy secondary to subacute sclerotic panencephalitis and measles virus: An immunohistochemical analysis in autopsy cases including cases treated with aggressive antiviral therapies.

Subacute sclerotic panencephalitis (SSPE) is a refractory neurological disorder after exposure to measles virus. Recently, SSPE cases have been treated with antiviral therapies, but data on the efficacy are inconclusive. Abnormal tau accumulation has been reported in the brain tissue of SSPE cases, but there are few reports in which this is amply discussed. Five autopsied cases diagnosed as definite SSPE were included in this study. The subject age or disease duration ranged from 7.6 to 40.9 years old or from 0.5 to 20.8 years, respectively. Cases 3 and 4 had been treated with antiviral therapies. All evaluated cases showed marked brain atrophy with cerebral ventricle dilatation; additionally, marked demyelination with fibrillary gliosis were observed in the cerebral white matter. The brainstem, cerebellum, and spinal cord were relatively preserved. Immunoreactivity (IR) against measles virus was seen in the brainstem tegmentum, neocortex, and/or limbic cortex of the untreated cases but was rarely seen in the two treated cases. Activated microglia were broadly observed from the cerebrum to the spinal cord and had no meaningful difference among cases. Neurofibrillary tangles characterized by a combination of 3- and 4-repeat tau were observed mainly in the oculomotor nuclei, locus coeruleus, and limbic cortex. IR against phosphorylated tau was seen mainly in the cingulate gyrus, oculomotor nuclei, and pontine tegmentum, and tended to be observed frequently in cases with long disease durations but also tended to decrease along with neuronal loss, as in Case 5, which had the longest disease duration. Since the distribution of phosphorylated tau was independent from that of measles virus, the tauopathy following SSPE was inferred to be the result of diffuse brain inflammation triggered by measles rather than a direct result of measles virus. Moreover, antiviral therapies seemed to suppress measles virus but not the progression of tauopathy.

A new species of Simulium (Gomphostilbia) (Diptera, Simuliidae) from Thailand, with a key to identify females of 14 species of the Simuliumvaricorne species-group.

Simulium (Gomphostilbia) khelangensesp. nov. is described on the basis of females, collected by a sweeping net in Lampang, Phitsanulok and Chiang Mai Provinces, Thailand. This new species is placed in the S.chumpornense subgroup of the S.varicorne species-group in the subgenus Gomphostilbia Enderlein by having the antenna with eight flagellomeres, pleural membrane bare, and female subcosta lacking hairs. It is similar to S.kuvangkadilokae Pramual & Tangkawanit from Thailand in the same subgroup but is barely distinguished from the latter species by the head width relative to the greatest width of the frons and length of the labrum relative to the clypeus. A genetic analysis using the COI gene sequences similarly shows that S.khelangense sp. nov. is most closely related to S.kuvangkadilokae, with a genetic distance of 1.23-2.81%. A revised key to identify females of 14 species of the S.varicorne species-group is provided.

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).

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.

Redescription of Simulium (Gomphostilbia) omutaense Ogata & Sasa (Diptera: Simuliidae) from Japan and its phylogenetic relationship with other members of the S. batoense species-group.

Simulium (Gomphostilbia) omutaense Ogata & Sasa, 1954 is the only named species in the Simulium batoense species-group of the subgenus Gomphostilbia Enderlein recorded from Honshu and Kyushu, Japan. It represents the northernmost distribution of this species-group, of which most members are distributed in the Oriental region. This species, the only member of the Simulium omutaense subgroup, is unique among the seven subgroups of the S. batoense species-group by having the pupal gill with one long filament and seven short filaments, similar to the arrangement of the pupal gill filaments in the S. zonatum subgroup of the S. epistum species-group in the same subgenus. This species is fully redescribed based on adults, pupal exuviae and mature larvae, and is most similar to species of the S. decuplum subgroup, based on adult morphological characteristics, although the pupal gill of the latter subgroup is markedly different by having 10 or 12 short filaments. Its close relationship to the S. decuplum subgroup is supported by a DNA analysis using COI gene sequences, with genetic distances of 9.30-11.02%. On the other hand, genetic distances between S. (G.) omutaense and species of the S. zonatum subgroup were 16.32-16.93%. Our study shows that a similar arrangement of the pupal gills in two different species-groups, which is rarely seen, has evolved independently and its occurrence does not necessarily reflect phylogenetic relationships.

Factors associated with successful phase III trials for solid tumors: A systematic review.

BACKGROUND: It is known that the success rates of phase III trials for solid cancers are low. The aim of this study was to investigate factors related to trial design and operation that were associated with the probability of the success of phase III trials for solid cancers based on the latest comprehensive data. METHODS: Relevant clinical trials, started between September 2007 and December 2017, were retrieved from ClinicalTrials.gov. Then, variables related to the selected trials such as types of primary endpoint and duration of trial enrollment were collected from the literature and ClinicalTrials.gov. Based on the collected data, a multivariate logistic regression analysis was conducted to find factors associated with the successful results. RESULTS: Four hundred phase III trials were found eligible for the study. Unsuccessful trials were 207 and successful trials were 193. As a result of multivariate logistic regression analysis, factors that presented a statistically significant relationship were primary endpoint (Odds ratio [OR]: 2.79 [95% CI: 1.59-4.89]), control arm (OR: 3.06 [95% CI: 1.39-6.73]), start year of trial (OR: 3.28 [95% CI: 1.87-5.77]), and duration of trial enrollment (OR: 0.77 [95% CI: 0.60-0.99]). CONCLUSION: Type of primary endpoints (time-to-event endpoints other than overall survival), control arm (treatments with lower evidence level, placebo or best supportive care), and duration of trial enrollment (faster enrollment speed) were associated with phase III trial success.

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.

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%.

Natural infections with larvae of Onchocerca species type I in the human-biting black fly, Simulium nigrogilvum (Diptera: Simuliidae), in western Thailand.

Zoonotic onchocerciasis is a human infection caused by Onchocerca species of animal origins and transmitted by black fly vectors. The reported incidence of this disease has increased throughout the world. This study aims to clarify the vectorial roles of black fly species in zoonotic filarial transmission in Tak province, western Thailand. The integrated approach of morphological and DNA sequence-based analyses was used to identify species of both wild-caught female black flies and infective filarial larvae found in the infected black flies. All of 494 female black flies captured were identified as Simulium nigrogilvum, through scanning electron microscopy (SEM) and DNA sequence analyses based on the cytochrome c oxidase subunit I (COI) and subunit II (COII), and the fast-evolving nuclear elongation complex protein 1 (ECP1) genes. Four females of S. nigrogilvum harbored one to three third-stage larvae (infective larvae) in their thoraces, with an infection rate of 0.81% (4/494). All infective larvae were similar in morphology and size to one another, being identified as Onchocerca species type I (= O. sp. type A), a bovine filaria, originally reported from Japan, and also as O. sp. found in S. nodosum in Thailand, based on their body lengths and widths being 1,068-1,346 µm long by 25-28 µm wide, and morphological characters. Comparisons of cytochrome c oxidase subunit I (COI) and 12S rRNA sequences of mitochondrial DNA (mtDNA) and phylogenetic analyses with those of previous reports strongly supported that all larvae were O. sp. type I. This report is the first indicating the presence of O. sp. type I in Thailand and its vector being S. nigrogilvum.

Revision of Simulium rufibasis (Diptera: Simuliidae) in Japan and Korea: Chromosomes, DNA, and Morphology.

The widespread nominal black fly Simulium (Simulium) rufibasis Brunetti was reexamined morphologically, chromosomally, and molecularly to determine the status of populations in Japan and Korea with respect to S. rufibasis from the type locality in India and to all other known species in the S. (S.) tuberosum species-group. Morphological comparisons established that the species previously known as S. rufibasis in Japan and Korea is distinct from all other species. Consequently, it was described and illustrated as a new species, Simulium (S.) yamatoense. Simulium yokotense Shiraki, formerly a synonym of S. rufibasis, was morphologically reevaluated and considered a species unplaced to species-group in the subgenus Simulium. Chromosomal analyses of S. yamatoense sp. nov. demonstrated that it is unique among all cytologically known species of the S. tuberosum group and is the sister species of the Taiwanese species tentatively known as S. (S.) arisanum Shiraki. Populations of S. yamatoense sp. nov. included two cytoforms, based on the sex chromosomes. Cytoform A, including topotypical representatives, was found in Kyushu, Japan, whereas cytoform B was found in Korea and Honshu, Japan. Molecular analysis based on the COI mitochondrial gene generally corroborated morphological and chromosomal data that S. yamatoense sp. nov. is a distinct species and, like the chromosomal data, indicate that it is most closely related to S. arisanum, with interspecific genetic distance of 2.92-4.63%.

Elevated quinolinic acid levels in cerebrospinal fluid in subacute sclerosing panencephalitis.

Subacute sclerosing panencephalitis (SSPE) is a rare neurodegenerative disorder caused by a persistent infection with aberrant measles virus. Indoleamine-2, 3-dioxygenase (IDO) initiates the increased production of kynurenine pathway (KP) metabolites quinolinic acid (QUIN), which has an excitotoxic effect for neurons. We measured serum IDO activity and cerebrospinal fluid (CSF) levels of QUIN. The CSF QUIN levels were significantly higher in SSPE patients than in controls, and increased according as neurological disability in a patient studied. Elevation of CSF QUIN and progression of SSPE indicate a pathological role of KP metabolism in the inflammatory neurodestruction.

Adjuvant therapy with nivolumab versus ipilimumab after complete resection of stage III/IV melanoma: Japanese subgroup analysis from the phase 3 CheckMate 238 study.

The multinational phase 3 CheckMate 238 trial compared adjuvant therapy with nivolumab versus ipilimumab among patients with resected stage III or IV melanoma (N = 906). In this Japanese subgroup analysis of CheckMate 238 (n = 28; nivolumab, n = 18; ipilimumab, n = 10), both the 12- and 18-month recurrence-free survival rates were 56% for nivolumab and 30% for ipilimumab (hazard ratio, 0.66; 97.56% confidence interval, 0.19-2.24; P = 0.4390). No new safety signals were reported for Japanese patients. Results were consistent with those from the CheckMate 238 global population, indicating that nivolumab has the potential to be a treatment option for Japanese patients with resected melanoma who are at high risk of recurrence.

A new species of the Simulium (Gomphostilbia) (Diptera: Simuliidae) from Thailand, with its phylogenetic relationships with related species in the Simulium asakoae species-group.

A new species of black fly, Simulium (Gomphostilbia) rampae, is described, based on adult male, its pupal exuviae and mature larvae collected from Doi Inthanon National Park, northern Thailand. This new species is placed in the Simulium asakoae species-group, and is characterized in the male by the high number of upper-eye facets in 17 vertical columns and 18 horizontal rows, in the pupa by the gill with a long common basal stalk, cone-shaped terminal hook, and cocoon with an anterodorsal projection, and in the larva by the medium-long postgenal cleft. A DNA analysis using COI gene supported its assignment to the S. asakoae species-group and showed its close relationship to S. (G.) udomi Takaoka & Choochote and S. (G.) chiangdaoense Takaoka & Srisuka. This is the fourth member of the S. asakoae species-group recorded from Thailand.

Human case of Onchocerca dewittei japonica infection in Fukushima, Northeastern Honshu, Japan.

A 73-year-old man living in Kawamata-machi, Fukushima Prefecture, Northeastern Honshu, Japan, visited a hospital with complaints of a subcutaneous swelling that had developed on the back of his left hand. The nodule was surgically removed from the vagina fibrosa tendinis of his left forefinger. Based on the histopathological characteristics, the causative agent of this nodule was identified as a female Onchocerca dewittei japonica (Spirurida: Onchocercidae). The species identification was confirmed by cox1 gene sequencing of the worm tissues from paraffin-embedded sections of the nodule. Although 11 cases of zoonotic onchocercosis have previously been recorded in Kyushu and Western Honshu, Japan, the present findings represent the first human case of infection with O. dewittei japonica in Northeastern Honshu, Japan.

Biodiversity, seasonal abundance, and distribution of blackflies (Diptera: Simuliidae) in six different regions of Thailand.

BACKGROUND: Blackflies are an important medical and veterinary group of small blood-sucking insects. Ninety-three blackfly species have been reported in Thailand. However, information on their biodiversity and population dynamics in each region is lacking. The main aim of this study was to assess the regional biodiversity, seasonal abundance and distribution of blackflies in six eco-geographically different regions in the country. METHODS: Blackfly larvae and pupae were sampled monthly from 58 sites between May 2011 and April 2013. Diversity parameters, seasonal abundance, regional distribution and frequency of species occurrence in stream sites were analyzed. RESULTS: A total of 19,456 mature larvae representing 57 species, and belonging to six subgenera in the genus Simulium Latreille (s.l.), were found. The five predominant taxa were S. fenestratum (8.6%), the S. asakoae complex (8.3%), S. nakhonense (7.5%), the S. siamense complex (7.4%) and the S. doipuiense complex (6.7%). The most frequent taxa at all sites were the S. asakoae complex (84.5%), followed by S. fenestratum (82.8%), the S. siamense complex (75.9%), S. decuplum (60.3%), S. nakhonense (58.6%) and the S. tani complex (48.3%). The richness of regional species was highest (40 species) in the north and predominated in the cold season. However, blackflies in the south predominated during the hot season. The highest numbers of blackflies collected from central, northeastern, eastern and western regions of the country were observed in the rainy season. Overall, the mean number of blackflies collected across the six regions during the rainy and cold season had no statistically significant difference, but it differed significantly in the hot season. CONCLUSIONS: Blackflies in Thailand were surveyed in all three seasons across six geographical regions. These findings demonstrated that blackfly communities at each stream site varied with seasonality, and the regional relative abundance of blackflies differed markedly in the hot season. It was also found that the occurrence and distribution of blackflies in each region were associated strongly with elevation.

Zoonotic infection with Onchocerca dewittei japonica in an 11-year-old boy in Kansai Region, Western Honshu, Japan.

An 11-year-old boy living in Otsu City, Shiga Prefecture, Kansai Region, Western Honshu, Japan had zoonotic onchocercosis. The patient developed a painful swelling on the little finger of his left hand. The worm detected in the excised mass had external transverse ridges but did not have inner striae in the cuticle. On the basis of the parasite's histopathological characteristics, the causative agent was identified as a female Onchocerca dewittei japonica (Spirurida: Onchocercidae). The species of the filarial parasite was confirmed by sequencing the cox1 gene of the parasite. The Japanese wild boar Sus scrofa leucomystax is a definitive host for O. dewittei japonica, which is then transmitted by blackflies as the vector to humans. The current case described occurred in the Kansai Region, Western Honshu, where such infections were previously not reported.

An effective method for the identification and separation of Anopheles minimus, the primary malaria vector in Thailand, and its sister species Anopheles harrisoni, with a comparison of their mating behaviors.

BACKGROUND: Species of the Anopheles minimus complex are considered to be the primary vectors of malaria in South and Southeast Asia. Two species of the complex, Anopheles minimus and Anopheles harrisoni, occur in Thailand. They are sympatric and difficult to accurately distinguish based on morphological characters. The aim of this study was to investigate the potential of antennal sensory organs to distinguish these two species. Additionally, we investigated their ability to mate in cages of different sizes, as well as the possible mechanism(s) that evokes stenogamous behavior. METHODS: Large sensilla coeloconica present on the antennae of females of An. minimus and An. harrisoni were counted under a conventional light microscope and various types of antennal sensilla were examined under a scanning electron microscope (SEM). Determinations of mating ability were carried out in 20 and 30 cm3 cages with a density resting surface (DRS) of 7.2. The insemination rate, frequency of clasper (gonocoxopodite) movement of the male genitalia during induced copulation and duration of mating of the two species were compared. RESULTS: The mean numbers of large sensilla coeloconica on antennal flagellomeres 1-8 and the mean number of large sensilla coeloconica on each flagellum in An. minimus (26.25) and An. harrisoni (31.98) were significantly different. Females of both species bear five types of antennal sensilla: chaetica, trichodea, basiconica, coeloconica and ampullacea. Marked differences in the structure of the large sensilla coeloconica were observed between the two species. Furthermore, only An. minimus could copulate naturally in the small cages. The frequency of clasper movement in the stenogamous An. minimus was significantly higher than in An. harrisoni, but there was no difference in the duration of mating. CONCLUSIONS: To our knowledge, this study is the first to examine and discover the usefulness of large sensilla coeloconica on the antennae of females and the frequency of clasper movement in males for distinguishing the sibling species An. minimus and An. harrisoni. The discovery provides an effective and relatively inexpensive method for their identification. Additionally, the greater frequency of clasper movement of An. minimus might influence its ability to mate in small spaces.

Scanning electron microscopy of antennal sensilla of the eight Anopheles species of the Hyrcanus Group (Diptera: Culicidae) in Thailand.

Antennal sensilla were first investigated in the eight medically and veterinary important Anopheles mosquito species (Anopheles argyropus, Anopheles crawfordi, Anopheles nigerrimus, Anopheles nitidus, Anopheles paraliae (= Anopheles lesteri), Anopheles peditaeniatus, Anopheles pursati, and Anopheles sinensis) of the Hyrcanus Group in Thailand, using scanning electron microscopy (SEM). Four types of sensilla, including sensilla chaetica (large and small), sensilla trichodea (sharp- and blunt-tipped), sensilla basiconica or grooved pegs (types I, II, and III), and sensilla coeloconica (large and small), were observed on the female antennae of the eight species. The greatest number of sensilla found along the flagellum of all the Anopheles species consisted of sensilla trichodea. Grooved pegs type II were not found on the antennae of An. peditaeniatus. Interestingly, clusters of 10-15 grooved pegs type III, with blunt-tipped and unevenly grooved-lengthwise sensilla, and a sunken group of 7-12 grooved pegs type III, with slightly curved and point-tipped sensilla, were found distally on flagellomeres 3-7 of An. argyropus and An. peditaeniatus, respectively. In addition, the key for species identification, based on fine structure and morphometrics of antennal sensilla among the eight species, was constructed and differentiated successfully. However, in order to focus intensively on the exact function of these sensilla, further electrophysiological study is needed in understanding their significant role in mosquito behavior, especially when these insects seek hosts for transmitting pathogens to humans.

Comparative Studies on the Stenogamous and Eurygamous Behavior of Eight Anopheles Species of the Hyrcanus Group (Diptera: Culicidae) in Thailand.

Establishment of laboratory colony is essential for mosquito-borne-disease research. Mating behavior of stenogamous Anopheles peditaeniatus and seven eurygamous species (Anopheles argyropus, Anopheles crawfordi, Anopheles nigerrimus, Anopheles nitidus, Anopheles paraliae (=An. lesteri), Anopheles pursati and Anopheles sinensis), were investigated and compared in this study. The self-mating success of adult mosquitoes in different size cages at two density resting surface (DRS) values, 3.6 and 7.2, was statistically significant between stenogamous and eurygamous species. The results obtained from comparative measurements of specific characters in adult females (maxillary palpomere and antennal sensilla characters) and males (wing and genitalia) indicate those characters might influence the mating success of An. peditaeniatus in a small cage. The gonostylus of An. peditaeniatus was shorter than the eurygamous species. Additionally, the lower frequency of clasper movement and shorter mating time could be important mechanisms that control the stenogamous behavior of An. peditaeniatus. Interestingly, for the first time, a cluster of large sensilla coeloconica was recorded on the antenna of An. argyropus and An. peditaeniatus females. There was no statistically significant difference in the mean number per female of those large antennal sensilla coeloconica among six of the eurygamous species.