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.


Introduction
The Greater Mekong Sub-region (GMS) is undergoing unprecedented demographic and environmental changes that threaten its ecosystem stability [109]. The sub-region is composed of six countries: China (Yunnan province and Guangxi Zhuang autonomous region), Laos, Myanmar, Thailand, Vietnam and Cambodia. Cambodia, bordered by Thailand, Laos and Vietnam, is considered the lowland region of the GMS. The country hosts the largest freshwater lake in Southeast Asia: the Tonle Sap, characterised by an unusual hydrological regime. Due to the biannual flow reversal of the Tonle Sap river into the Mekong river, the lake can become four times larger in the rainy season than during the dry season. When flooded, the lake covers up to three million hectares, making it one of the world's largest wetland areas [76]. Cambodia is facing one of the world's highest deforestation rate [42,108,109]. Therefore, interfaces between anthropic areas and forests are rapidly blurring, increasing the risk of the population being exposed to new emergent diseases and vectors. This change in land use shifts the risk of mosquito-borne disease emergence by changing the relationship between mosquitoes and their hosts, both qualitatively and quantitatively [16,38,39]. Urbanisation may facilitate the dispersion of anthropophilic mosquito species into previously unfavorable habitats [51,52]. This modifies vectorhost interactions, and potentially leads to more contact with sylvatic reservoirs of zoonotic pathogens [16]. Consequently anthropophilic, and opportunistic mosquito species may act as bridge vectors between sylvatic and urban pathogen transmission cycles. It is therefore essential to know the diversity of mosquitoes and potential vector species, to be prepared to recognize and cope with emergent or re-emergent arthropodborne diseases.
In the Greater Mekong sub-region, several mosquito checklists have been produced. In Thailand, at least 464 species were recorded [26,69,97], 170 from Laos [46] and 191 from Vietnam [10]. In Cambodia, no such work has yet been undertaken. The only comprehensive studies of generic level groups Distribution: Cambodia, Indonesia, Malaysia, Singapore, Thailand and Vietnam [68]. Larvae can be found in shaded, dark, acidic water with emergent vegetation or numerous leaves inside the water. Habitats include freshwater swamps, jungle pools and large isolated stream pools. Adults bite at night [27,70]. Primary malaria vector in Malaysia [70].

Subfamily Culicinae Meigen, 1818
Tribe: Aedeomyiini Theobald, 1901 Genus Aedeomyia Theobald, 1901 (1 sp.) The genus Aedeomyia includes seven species subdivided into two subgenera: Aedeomyia and Lepiothauma [25]. Only one species belonging to the subgenus Aedeomyia is currently known from Cambodia. These small-sized nocturnal mosquitoes feed mainly on birds and occasionally on humans. Immature stages are often found in association with aquatic vegetation, especially Pistia, Salvinia, Eichhornia and Potamogeton [25].
Tribe: Aedini Neveu- Lemaire, 1902 Genus Aedes Meigen, 1818 (55 spp.) The genus Aedes comprises 79 subgenera [25,86]. Aedes mosquitoes have a worldwide distribution, and some species are considered to be of medical importance as they transmit pathogens. The taxonomic nomenclature follows Wilkerson et al. [107].  [71]. Immature stages can be found in freshwater flood pools, but have also been collected in ditches, swamps, rice fields, and elephant footprints. Habitats usually have little aquatic vegetation or algae. Females bite at night and readily feed on humans and cattle [71]. Species considered to be of medical importance. Confirmed vector of Japanese Encephalitis virus [6] and capable of transmitting Rift valley fever, eastern equine encephalitis virus (EEE), western equine encephalitis virus (WEE), St. Louis encephalitis virus (SLE) and West Nile Virus (WNV) [21,64,98]. It is also a vector of dog heartworm [71].
Distribution: China and Thailand [64,74]. Collected in Rattanak Kiri province, using a light trap in the primary forest.
Aedes (Bothaella) kleini (Reinert, 1973 [64]. Immature stages are found in natural containers, including tree holes, bamboo stumps, coconut shells, rockholes, palm fronds, and leaf axils. They can also be found in all varieties of artificial containers and will breed indoors. Distribution: Taiwan and Thailand [64]. Collected in Mondul Kiri province only from larvae collected in transparentbut colored with tanninwater in dead bamboo trees. Aedes (Stegomyia) pseudalbopictus (Borel, 1928). New record for Cambodia.
Distribution: India, Indonesia, Laos, Malaysia, Myanmar, Nepal, Taiwan, Thailand and Vietnam [64]. Collected in Mondul Kiri province only, from larvae collected in transparentbut colored with tanninwater in dead bamboo trees and from large tree holes.
Distribution: Australia, Cambodia, Fiji, Guam, India, Indonesia, Mariana Islands, Micronesia, Papua New Guinea, Philippines, Sri Lanka, Tuvalu and Vanuatu [64]. Immature stages have been collected from coconut shells and artificial containers [28]. Possible vector of dengue [28]. The genus Armigeres is composed of 58 species divided among two subgenera: Armigeres and Leicesteria [25]. Both are represented in Cambodia by 12 and 14 species, respectively. Immature stages are found in small collections of water, particularly those containing foul water or with a high organic content. They occur in hollow logs, rock holes, tree holes, stump holes, bamboo, Pandanus axils, sago palm and banana stumps, fruit shells and husks, fallen leaves and spathes, flower bracts, pitcher plants, artificial containers that contain organic matter and small collections of groundwater. Larvae are partially carnivorous. Adults occur primarily in forested and plantation areas and are mainly diurnal and active at dusk. Females of many species bite humans.
Genus Heizmannia Ludlow, 1905 (10 spp.) This genus comprises 40 species divided among two subgenera (Heizmannia, Mattinglyia) [25,47]. Both are present in Cambodia, hosting eight and two species, respectively. Larvae are found mainly in tree holes and bamboos, but some species are occasionally found in small ground pools. Little is known about the biology of the adults: they are apparently active during daytime in forests where females readily bite humans [41]. No species is reported to be of medical importance.
Distribution: Cambodia, India, Malaysia and Thailand [64]. Immature stages can be found in bored bamboos and in flood pools in bamboo groves [41]. Adults are known to bite humans during the daytime [41]. Distribution: Cambodia, India, Laos, Malaysia, Myanmar, Thailand and Vietnam [64]. Immature stages can be found in tree holes and bored bamboo [41]. Adults can feed on humans in dense forests during the daytime. Immature stages and adult male unknown. Distribution: Cambodia and Thailand [64]. Holotype bred from tree hole, and paratype collected from water in a split bamboo [41]. Adults are known to bite humans [41].
Heizmannia (Heizmannia) reidi Mattingly, 1957. Distribution: Cambodia, India, Malaysia, Myanmar, Nepal, Taiwan, Thailand and Vietnam [64]. Immature stages can be found in tree holes, bamboo internodes, ground pools and bamboo stumps. Adults readily bite humans [41]. Distribution: Cambodia, Indonesia, Malaysia, Philippines, Singapore, Thailand and Vietnam [64]. Immature stages can be found in tree holes, bamboo internodes and banana axils water [41]. Adults can bite humans in shaded forests. Distribution: Cambodia, Indonesia, Malaysia and Thailand [64]. Adults can feed on humans in shaded forests. Immature stages were found in water from tree holes and fallen coconut leaves [41].
Distribution: Cambodia, Taiwan and Thailand [64]. Adults can feed on humans in shaded forests during the daytime. Only known breeding place for immature stages is bamboo stumps [41].
Genus Verrallina Theobald, 1903 (19 spp.) The genus Verrallina includes 95 species distributed worldwide, and separated in three subgenera: Verrallina, Harbachius, and Neomacleaya [25]. These three subgenera are present in Cambodia, hosting 2, 5 and 12 species, respectively. The immature stages are found in temporary ground pools. Several species are reported to bite humans during the daytime, often in shaded places or in the vicinity of forests. Immature stages unknown [17]. Distribution: Cambodia and Malaysia [72].
Distribution: Cambodia, Malaysia and Thailand [64]. Larvae can be collected in flood pools in rainforests [17].
Immature stages can be collected in various types of temporary ground pools and in axils of the Colocasia plants. Adults are diurnal and can readily bite humans [17].
Genus Culex Linnaeus, 1758 (57 spp.) The genus Culex consists of 779 species divided among 26 subgenera [25]. In Cambodia, five subgenera are represented: Culex (15 species), Culiciomyia (five species), Eumelanomyia (11 species), Lophoceraomyia (18 species) and Oculeomyia (three species). Culex larvae occur primarily in semi-or permanent bodies of groundwater and can be found in artificial containers. Culex females feed mainly during the night. Some species are reported to be of medical importance and can be vectors of numerous arboviruses and filariosis [25].
The genus Culiseta includes 39 species divided among 7 subgenera (Allotheobaldia, Austrotheobaldia, Climacura, Culicella, Culiseta, Neotheobaldia, and Theomyia) [25]. The Culiseta are large mosquitoes and cold-adapted species which occur only in warmer climates during the colder times of the year or at higher elevations where temperatures are low. Only the subgenus Culimacura is present in Cambodia with one species. Immature stages of Culiseta (Climacura) species are usually found in permanent bodies of water, mainly swamps, but may also inhabit semi-permanent pools. Females primarily feed on birds but can occasionally feed on humans. Distribution: Cambodia and Malaysia [18].
Genus Lutzia Theobald, 1903 (3 spp.) The genus Lutzia includes 9 species divided among 3 subgenera: Insulalutzia, Lutzia, and Metalutzia [25,85]. Only the latter is represented in Cambodia by 3 species. Adults are large, and females feed on livestock, and rarely on humans. Very little information is known about the biology of the adults. Larvae are predaceous and occur in a wide variety of groundwater habitats, from tree holes to artificial cavities. Generally, they appreciate water with high organic content [25].  [66]. Upon hatching, the larvae will immediately consume nearby, similarsized, larvae. Adult female seems to feed preferentially on avian hosts [7].
Distribution: Australia, Bangladesh, Cambodia, China, India, Indonesia, Japan, Koreas, Malaysia, Nepal, Pakistan, Papua New Guinea, Philippines, Russia, Singapore, Solomon Islands, Sri Lanka, Taiwan, Thailand, Timor and Vietnam [66]. The larvae can be found in various kinds of temporary and semipermanent groundwater habitats and occur frequently in artificial containers as well as rock pools, stream margins and tree cavities [7]. The larvae prefer water containing high organic content. They are predaceous and can attack other arthropods nearby. The host preference for the adult female is not known, but humans have been reported to be an occasional host [7]. The genus Ficalbia is represented by 8 species present in the Afrotropical, Palearctic and Oriental regions [25]. Only one species is present in Cambodia. Very little is known about the biology of this genus. Their larvae can be found in swamps, marshes, ponds, pools and river margins with abundant vegetation. Nothing is known about the biting habits of females [67].
The 3 subgenera are present in Cambodia hosting 2, 2 and 3 species, respectively. Mimomyia are generally small mosquitoes. Very little is known about the biology of this genus. The larvae of most species occur in swamps and marshes with dense vegetation. The larval siphon of several species is modified for piercing aquatic plants to obtain oxygen. Larvae of subgenus Ingramia are found in the leaf axils of plants. The adults of several species have been reported to bite humans, but none are serious pests. Most species appear to be active at night. The genus Hodgesia consists of 11 species [25]. These mosquitoes are minute in size, and the immature stages can be found in swamps and marshes, in water containing very dense vegetation, often associated with larvae of Mimomyia spp. The feeding habits of most species are unknown, but some species have been reported to bite humans [25]. The genus Coquillettidia consists of 58 species, generally large, and yellowish [25]. The genus is subdivided into 3 subgenera: Austromansonia, Rhynchotaenia, and Coquillettidia [25]. Only the latter is present in Cambodia and comprises 3 species. Their larvae attach themselves to aquatic plants to obtain oxygen. Adult females are known to bite humans and domestic animals [59]. The genus Mansonia includes 25 species subdivided into 2 subgenera [25]. The subgenus Mansonia comprises 15 species distributed in the New World, while Mansonioides occurs in the Old World and consists of 10 species. Only the latter is present in Cambodia with 5 species. The larvae of Mansonia occur in permanent waters in association with aquatic plants and attach themselves to their floating roots in order to obtain oxygen. Females of several species are nocturnal, and are known to transmit several arboviruses [25].  [67]. Immature stages can be found in shaded pools in swamp forest. Adults are crepuscular and females seem to prefer cattle but can feed on humans [102].
The genus Orthopodomyia consist of 36 species distributed worldwide. Very little is known about their biology. Larvae occur principally in tree holes, but some species are found in bamboo internodes, inside Bromeliaceae and Heliconia plants. The larvae can sometimes be found in artificial containers. Adults are nocturnal and are found mainly in forests. The feeding habits of females are largely unknown, but they are probably ornithophilic. Two species in the Oriental Region are known to approach and bite humans. This genus is not considered to be of medical importance [25]. Barraud, 1934. Distribution: Andaman Islands, Cambodia, Indonesia, Malaysia, Philippines, Thailand and Vietnam [65]. The immature stages have been observed to breed in tree holes, bamboo stumps and artificial containers [110]. In Cambodia, the larvae were collected in artificial containers.

Orthopodomyia (Orthopodomyia) anopheloides (Giles, 1903).
Distribution: Cambodia, China, India, Indonesia, Japan, Malaysia, Nepal, Pakistan, Philippines, Singapore, Sri Lanka, Taiwan, Thailand and Vietnam [65]. The immature stages have been observed in tree holes, bamboo stumps and artificial containers [110]. The genus Malaya is a small group represented by only 12 species [25]. The immature stages can be found in plant cavities, such as leaf axils, tree holes or water-filled nests of arboreal ants. The adults are diurnal and incapable of taking a blood meal. Their feeding habits are unique among mosquitoes: they feed on the regurgitation of ants: specifically, both sexes obtain a sugar meal from ants that have collected honeydew from scale insects (Hemiptera: Coccoidea). To accomplish this, the mosquito accosts an ant and brings the tip of its proboscis into contract with the mouth of the ant until a drop of liquid is produced. The regurgitated liquid is rapidly sucked up and the ant goes away unharmed. This genus is represented by two species in Cambodia.

Malaya (Malaya) genurostris Leicester, 1908.
Distribution: Australia, India, Indonesia, Japan, Malaysia, Maldives, Myanmar, Papua New Guinea, Philippines, South China, Singapore, Taiwan, Thailand and Sri Lanka, [44]. The genus Topomyia includes 65 species in 2 subgenera: Miyagiella and Topomyia. Only the latter is present in Cambodia represented with 4 species. Topomyia are considered forest mosquitoes. Very little is known about the biology of the adults, but as females do not feed on humans they are not considered to be of medical importance. The larvae can be found in leaf axils, Nepenthes pitcher plants, bamboo internodes and stumps and sometimes tree holes [25].
Subgenus Topomyia Leicester, 1908 (4 spp.)  Distribution: Cambodia and Thailand [34,65].  Described from Cambodia [34], recorded from Philippines (Palawan islands). According to Miyagi et al. [43], this species has very particular habits: the larvae were only collected in bamboo internodes bearing a tiny hole bored by a beetle. The larvae preys upon small crustacean and chironomid larvae. The genus Tripteroides hosts 122 species divided into five subgenera: Polylepidomyia, Rachionotomyia, Rachisoura, Tricholeptomyia and Tripteroides. Only 2 (Rachionotomyia and Tripteroides) are present in Cambodia. The larvae inhabit small collections of water in tree holes, bamboo, coconut shells and husks, fallen leaves, pitcher plants or even snail shells. They feed on arthropods or their remains. Adults are diurnal. A few species feed on humans, but nothing is known about the feeding habits of most species [25]. Distribution: India, Sri Lanka and Thailand [65]. Collected in Cambodia from larvae reared from Nepenthes water, collected in the primary forest of Rattanak Kiri and Mondul Kiri provinces.
Genus Toxorhynchites Theobald, 1901 (4 spp.) The genus Toxorhynchites comprises 89 species worldwide, divided into 4 subgenera: Afrorhynchus, Ankylorhynchus, Lynchiella and Toxorhynchites [25]. The Cambodian species belong exclusively to the subgenus Toxorhynchites. The larvae are predators, feeding mainly on other mosquito larvae. They can be found in plant cavities, mainly tree holes and bamboo stumps [95]. Adults are covered with iridescent scales and are typically large and colorful mosquitoes. Both males and females are diurnal and feed exclusively on nectar and other sugary substances. They do not display blood-sucking behavior and are not considered to be of medical importance, but their larvae can be used for pest control [14,87]. This genus includes 271 species worldwide divided into 2 subgenera: Pseudoficalbia and Uranotaenia. Both are present in Cambodia, hosting 13 and 14 species, respectively [25]. The feeding preferences of most species are currently unknown but field observation tends to indicate that amphibians, reptiles, birds and mammals serve as hosts. Females can bite humans but do not seem to be involved in pathogen transmission. Immature stages can be found in a wide range of habitats: most species inhabit groundwaters, including swamps, marshes, stream margins and temporary pools with vegetation, but many also use crab holes, tree holes, bamboo, plant parts on the ground, leaf axils, flower bracts, pitcher plants or artificial containers [25].
Subgenus Pseudoficalbia Theobald, 1912 (13 spp.) Uranotaenia (Pseudoficalbia) abdita Peyton, 1977. Distribution: Cambodia and Thailand [55]. Immature stages seem to be associated with crab holes, and occur essentially in small freshwater crab holes at the margin of shallow running mountain or foothill streams, or at the edge of springs or seepages and generally under the cover of secondary or primary forests. Adults can be observed resting on rocks over streams, up to an elevation of 1000 m [55].  [55,67]. According to Peyton [55], this species is the most common of the genus in Southeast Asia, immature stages tend to colonize a very wide range of aquatic habitats. While it is present to an elevation up to 1000 m, most of the collection (95%) is below 350 m. Peyton & Klein, 1970. Distribution: Thailand and Cambodia [55]. Immature stages can be found in swamps, seepage pool or bog, or stream pool [67].
Distribution: Australia, Cambodia, Indonesia, Malaysia, Papua New Guinea, Singapore, Solomon Islands and Thailand [67]. Most of the collection of immature stages was done in crab holes and marsh swamps areas [55]. Peyton & Klein, 1970. Distribution: Cambodia, Thailand and Vietnam [55]. Species restricted to forested hills and mountainous areas. Immature stages can be collected in crab holes on the banks of shallow fresh running streams and elephant footprints in bogs where crab holes were present. Adult often rest on vegetation or rocks along stream margins [55].
Distribution: Cambodia, India, Malaysia, Thailand and Vietnam [55,67]. Prefer secondary forests where bamboo habitats are abundant. Immature stages show a preference for a variety of bamboo habitats, located on or near the ground, bamboo internodes, with small or moderate entrance holes, bamboo stumps, cut bamboo, or tree stumps. Most collections were done at an elevation below 600 m [55]. Collected in Cambodia from primary forest in Mondul Kiri province, the immature stages were collected from transparent water colored with tannin in bamboo tree holes. Distribution: Cambodia, China, Hong Kong, India, Indonesia, Japan, Laos, Malaysia, Nepal, Singapore, Sri Lanka, Taiwan, Thailand and Vietnam [55,67]. Immature stages collected from tree stumps tree holes and artificial containers. Mainly found in forests and anthropic environments at elevations up to 2286 m [55].

Species
Disease/parasite potentially hosted Aedes Distribution: Australia, Cambodia, India, Indonesia, Malaysia, Papua New Guinea, Philippines, Singapore, Sri Lanka and Thailand [55,67]. Immature stages can colonize a variety of habitats, usually containing a small amount of water, including both natural and artificial containers, often found associated with Aedes, Armigeres, Culex and Zeugnomyia larvae [55].
Uranotaenia (Uranotaenia) sombooni Peyton & Klein, 1970. Egg unknown. Distribution: Cambodia, Malaysia and Thailand [54,67]. Species apparently restricted to forested hill and mountainous areas, breeds commonly in partially to heavily shaded streams and seepage pools with abundant dead leaves and sticks, but could also be collected from rock pools [54]. Distribution: Cambodia, Malaysia and Thailand [67].

Diversity of the Cambodian Culicidae fauna
Between 2016 and 2020, the medical and veterinary entomology of IPC collected more than 230,000 mosquitoes belonging to 193 species of mosquitoes from 16 genera. This unprecedented sampling and identification effort allowed us to increase previous estimates from 241 species [25,32] to 290 species. We focused the collecting efforts on 11 provinces with diverse ecological settings and biotopes, namely Battambang, Kampong Cham, Kompong Thom, Kompong Saom, Koh Kong, Mondul Kiri, Phnom Penh, Pursat, Preah Viehar, Rattanak Kiri and Siem Reap. However, this sampling is only partial: the country comprises 24 provinces [79] and some of them have a great biological potential. But due to past conflicts, land mine presence or just accessibility, some regions have been underif not at allstudied over the past decades. Consequently, we can expect many more species to be added to the list in the future. An important limitation of our work is that the identifications were done only morphologically on adults, mostly females. It is certain that species complexes also exist outside the genus Anopheles. The probable sibling species, for example in the genera Culex or Aedes, remain to be discovered.
As a comparison, the fauna of Thailand, with which Cambodia shares a similar fauna, comprises 174 more species (n = 464) than Cambodia [64], highlighting the fact that many new records, and probably new species are expected to be described. Further collecting efforts should concentrate on areas like the Cardamone, Kampot, or the Aoral mountains, and the forests in Rattanak Kiri and Mondul Kiri hosting some of the most biologically diverse biomes in the country [48,79].
However, despite our collection efforts, some species previously listed, only from Cambodia, were not found. This is the case for Aedes (Bothaella) kleini Reinert, 1973, collected in Kampong Speu, Verrallina (Harbachius) stunga (Klein, 1973), (male and immature stages unknown) collected in Stung Chral, Kompong Sela province; Verrallina (Neomacleaya) komponga (Klein, 1973), known only by the male, collected in Kiriom hills, from Kompong Speu province; Culex (Eumelanomyia) bokorensis Klein & Sirivanakarn, 1970, known only by the male, collected in Bokor Hill, in Kampot province and Mimomyia (Ingramia) kiriromi (Klein, 1969), known only by the adults, collected in Kirirom hills, from Kompong Speu province. Our identifications, based on morphological features of adults, focused mainly on female-determination keys; therefore, it is possible that these species (two of them being known only by the male) remained undetected by our prospections. It is difficult to determine whether these species are endemic from Cambodia, or are only the result of a lack of prospection in neighboring countries. Most likely, as they are present in the lowland region of the Greater Mekong Region, they might be present in eastern Thailand or southern Vietnam.
Similarly, some species previously known only from Thailand were collected for the first time in another country [64]. This is the case for Uranotaenia (Pseudoficalbia) albipes Peyton, 1977,  The similarity with the Vietnamese and Thai fauna is the strongest. For Vietnam, it can be explained by two factors: first by the continuity of the Tonle Sap Mekong peat swamp forest ecosystem in the south, the Southern Annamite mountain rainforest, and Southeastern Indochina dry evergreen forest ecosystems on the east and the north [109] and secondly, by the low species number in the country. Out of the 191 known species in Vietnam [10], 176 are also known in Cambodia. Vietnam covers more than 331,000 km 2 and stretches across 1650 km from North to South, and hosts a large range of biologically diverse habitats, most of which have been undersampled. Consequently more species are expected to be found in the country [10]. Further studies in Vietnam are required to assess the actual number of mosquito species [10] and will help to provide a better assessment of the similarities of the two fauna.
Regarding the Thai fauna (with which Cambodia shares 71.80% of its Culicidae fauna), the proximity can be explained by the ecosystem continuity between the two countries, sharing a similar floral pattern (as for instance the Central Indochina dry forests and the Southeastern Indochina evergreen forests). In addition, the eastern part of Thailand belongs to the lowlands of the Mekong Region [109], extending through Cambodia, to southern Vietnam, allowing species move across the area.
Finally, the low proximity (32.33%) with Laos can be directly explained by the lack of studies of their Culicidae fauna, having only 170 species [46]. Like for Vietnam, is it most likely that this number is highly underestimated considering the important number of biologically diverse ecosystems in the country. Moreover, the provinces of Rattanak Kiri and Mondul Kiri directly bordering Laos were not investigated in-depth, therefore new records and perhaps new species are expected to be found in this region, and might increase the similarity index percentage with Laos.

Medically important species
In Cambodia, at least 43 mosquito species are considered to be potentially of medical importance to humans (Table 1).
For arboviruses, regarding dengue, the two main vectors are present: Ae. aegypti and Ae. albopictus. Three lesser vectors are also recorded: Ae. scutellaris, Ae. malayensis and Ar. subalbatus [28]. Three Aedes species are known to be involved in the transmission or able to transmit experimentally, or naturally, yellow fever virus: Ae. albopictus, Ae. aegypti and Ae. scutellaris, even though no outbreaks have yet been recorded in Asia [8,13,106]. The four species Ae. aegypti, Ae. albopictus, Cx. quinquefasciatus and Ma. uniformis are known to be vectors of the West Nile Fever [98]. The two main vectors of chikungunya, Ae. albopictus and Ae. Aegypti, are present in Cambodia, along with Ae. vexans and Ma. annulifera known to be its lesser vectors [6,28,95,104]. Cambodian mosquitoes, especially forest mosquitoes, are most likely involved in the transmission of undiscovered forest arboviruses to wild vertebrate species.
In Cambodia, 10 species are known to be potential vectors of filariosis although these parasites have not yet been detected in the country. Anopheles sinensis, An. maculatus, Cx. sitiens and Ma. annulifera are known to only transmit B. malayi, while An. jeyporiensis, Ae. togoi and Cx. bitaeniorhynchus transmit it along with W. bancrofti. Anopheles whartoni and Ar. subalbatus carry only W. bancrofti. Only three species in Cambodia, Ae. togoi, Ae. vigilax and Ve. butleri, can transmit Dirofilaria immitis [24,94].

Conclusion
A total of 290 mosquito species belonging to 20 genera are recorded from Cambodia with at least 43 medically important species. Forty-nine species are new records for the country. While being only preliminary, this number is expected to increase in the near future, as studies of the Cambodian fauna will continue, including use of genetic/molecular approaches. As many areas of biological interest have not been yet sampled, it is most likely that many new species are to be discovered in remote areas. Further particular efforts should be done on larval prospection and investigation of unusual habitats such as caves, remote forests or karstic massifs. Implementation of new determination techniques, such as MALDI-TOF which focus on the protein profile of the sample, will help to determine specimens rapidly and at lower cost, fastening the identification rate of the entomologists and potentially highlighting cryptic or problematic species.
The influence of climate change will, in the near future, affect the distribution of the mosquitoes and some species might occur in areas where they were previously absent. Similarly, the high deforestation rate the country is actually facing might place in contact mosquitoes vectors, humans and new viruses. This can therefore represent a cradle for the emergence of new infectious diseases. This perspective stresses the essential role of closely monitoring mosquito diversity and the viruses they can carry, in order to defuse any potential threats as much as possible before they appear.