Morphological and molecular evidence for a new species of Lutzia (Diptera: Culicidae: Culicini) from Thailand

Antennal morphology and sensilla ultrastructure of the malaria vectors, Anopheles maculatus and An. sawadwongporni (Diptera: Culicidae)

Mosquitoes rely mainly on the olfactory system to track hosts. Sensilla contain olfactory neuron receptors that perceive different kinds of odorants and transfer crucial information regarding the surrounding environment. Anopheles maculatus and An. sawadwongporni, members of the Maculatus Group, are regarded as vectors of malaria in Thailand. The fine structure of their sensilla has yet to be identified. Herein, scanning electron microscopy is used to examine the sensilla located on the antennae of adults An. maculatus and An. sawadwongporni, collected from the Thai-Myanmar border. Four major types of antennal sensilla are discovered in both species: chaetica, coeloconica, basiconica (grooved pegs) and trichodea. The antennae of female An. maculatus have longer lengths (μm, mean ± SE) in the long sharp-tipped trichodea (40.62 ± 0.35 > 38.20 ± 0.36), blunt-tipped trichodea (20.39 ± 0.62 > 18.62 ± 0.35), and basiconica (7.84 ± 0.15 > 7.41 ± 0.12) than those of An. sawadwongporni. Using light microscopy, it is found that the mean numbers of large sensilla coeloconica (lco) on both flagella in An. maculatus (left: 32.97 ± 0.48; right: 33.27 ± 0.65) are also greater when compared to An. sawadwongporni (left: 30.40 ± 0.62; right: 29.97 ± 0.49). The mean counts of lco located on flagellomeres 1-3, 6, and 9 in An. maculatus are significantly higher than those of An. sawadwongporni. The data in this study indicate that two closely related Anopheles species exhibit similar morphology of sensilla types, but show variations in length, and likewise in the number of large sensilla coeloconica between them, suggesting they might be causative factors that affect their behaviors driven by the sense of smell.

Review of the Mimeticus Subgroup of Culex (Culex) (Diptera: Culicidae), With an Assessment of the Specific Status of Three Nominal Species Described From India

The Mimeticus Subgroup of the subgenus Culex, genus Culex Linnaeus, is reviewed and revised. Mitochondrial COI sequences of species of the subgroup available in GenBank were analysed to verify the identity of voucher specimens. The specific status of three species described from India, Cx. gaugleri Suman, Cx. katezari Karlekar, Andrew & Deshpande, and Cx. kodaikanalensis Suman, Veer & Chandra, was examined and found to be unsupportable. Culex gaugleri and Cx. kodaikanalensis are synonyms of Cx. jacksoni based on the similarity of DNA sequences and dubious evidence of morphological differentiation. Culex katezari is recognized as a nomen dubium because the morphological description and molecular information provided by the authors are insufficient for its identification. A number of specimens registered in GenBank were found to be misidentified. In addition, available data indicate that the Mimeticus Subgroup may include at least three unrecognized species, referred to informally as Cx. mimeticus form B, Cx. mimulus form X, and Cx. mimulus form Y.

Evaluation of Modern Techniques for Species Identification of Lutzia Mosquitoes (Diptera: Culicidae) in Thailand: Geometric Morphometrics and DNA Barcoding

There are four species of Lutzia mosquitoes in Thailand, including Lutzia chiangmaiensis, Lt. fuscana, Lt. halifaxii, and Lt. vorax. The accurate species identification of adult Lutzia mosquitoes based on morphological features requires many body parts, including the abdominal terga and wing. However, species identification is difficult in the case of damaged specimens when some of their morphological character is missing due to transit or gathering in the field. Thus, we evaluated the efficacy of the landmark-based geometric morphometric (GM) approach for the discrimination of Lutzia species in Thailand. In addition, DNA barcoding was also used in parallel with the GM approach to identify the species. Larvae of Lutzia were collected, raised into adults, and identified based on their morphological characteristics. The validated reclassification test results clearly demonstrated that wing shape resulted in a high level of success in identification (correct identifications ranged from 92.50% to 100%); however, based on the DNA barcoding analyses, our results showed that it was poorly effective in identifying Lt. fuscana and Lt. halifaxii based on an overlap between the intraspecific and interspecific divergence. Moreover, our survey results provide updates on the distribution of Lt. chiangmaiensis and Lt. vorax in Thailand. This research will help medical entomologists more efficiently identify mosquitoes in the genus Lutzia, resulting in more effective mosquito control and surveillance.

The Anopheles baileyi species complex (Diptera: Culicidae: Anophelinae) in Bhutan

This paper deals with three species (informal species A, B and C) of the Baileyi Complex of Anopheles subgenus Anopheles (Diptera: Culicidae) that were recently reported from Bhutan. Species A is An. baileyi sensu stricto, while species B and C are new species which are formally described and named herein as An. monticola Somboon, Namgay & Harbach and An. bhutanensis Somboon, Namgay & Harbach, respectively. Morphological characters of the adults, male genitalia, larval and pupal stages of the two new species, and the chaetotaxy of the immature stages, are provided and compared with An. baileyi from Bhutan. Although the patterns of wing spots of the adults and the pupal setae of the three species are very similar, significant differences in structures of the male genitalia distinguish them. Larvae of An. baileyi and An. monticola are similar, but differ from the larva of An. bhutanensis in the development of setae 3- and 13-T. The first antennal flagellomere of females of An. baileyi and An. bhutanensis has a distinct patch of pale scales, which is absent in An. monticola.

Checklist of the mosquito fauna (Diptera, Culicidae) of Cambodia

Between 2016 and 2020, the Medical and Veterinary Entomology unit of the Institut Pasteur du Cambodge collected over 230,000 mosquitoes. Based on this sampling effort, a checklist of 290 mosquito species in Cambodia is presented. This is the first attempt to list the Culicidae fauna of the country. We report 49 species for the first time in Cambodia. The 290 species belong to 20 genera: Aedeomyia (1 sp.), Aedes (55 spp.), Anopheles (53 spp.), Armigeres (26 spp.), Coquillettidia (3 spp.), Culex (57 spp.), Culiseta (1 sp.), Ficalbia (1 sp.), Heizmannia (10 spp.), Hodgesia (3 spp.), Lutzia (3 spp.), Malaya (2 spp.), Mansonia (5 spp.), Mimomyia (7 spp.), Orthopodomyia (3 spp.), Topomyia (4 spp.), Toxorhynchites (4 spp.), Tripteroides (6 spp.), Uranotaenia (27 spp.), and Verrallina (19 spp.). The Cambodian Culicidae fauna is discussed in its Southeast Asian context. Forty-three species are reported to be of medical importance, and are involved in the transmission of pathogens.

Culex bhutanensis, a new species of the Mimeticus Subgroup of the nominotypical subgenus of the genus Culex Linnaeus (Diptera: Culicidae) from Bhutan

Culex bhutanensis Somboon, Namgay & Harbach is described as a new species of the Mimeticus Subgroup of the subgenus Culex Linnaeus. Based on morphological distinctions and phylogenetic analysis of COI sequences, the new species is a member of the Mimulus Complex. The adults have wing markings similar to those of Cx. mimulus Edwards and Cx. murrelli Lien, but are distinguished by the presence of a line of pale scales or scattered pale scales along the posterior margin of the proximal portion of the costa. The larva is most similar to the larva of Cx. orientalis Edwards from Japan and South Korea, but is distinguished by the form of the comb scales, pecten spines and seta 2-X. The pupa differs from the pupae of other species of the subgroup in having seta 8-C with more branches. The immature stages of the new species were found in rice paddies, stagnant pools and marshes at high altitudes in several districts of Bhutan.

Lutzia (Metalutzia) chiangmaiensis n. sp. (Diptera: Culicidae), Formal Name for the Chiang Mai (CM) Form of the Genus Lutzia in Thailand

The Chiang Mai (CM) form of the genus Lutzia, subgenus Metalutzia, in Thailand is diagnosed and formally named Lt. chiangmaiensis Somboon & Harbach, n. sp. The species is contrasted with related species, and information is provided on its bionomics and distribution.