Morphological and genomic characterization of sand flies (Diptera: Psychodidae) with different taxonomic features from three districts in Sri Lanka and the report of a novelSergentomyiaspecies

Abstract

Objective: To characterize morphologically distinct sand flies collected from three districts in Sri Lanka using integrated morphological and molecular approaches.Methods: Sand fly specimens received by the Department of Parasitology, University of Kelaniya, Sri Lanka, between January and December 2024, were examined. Specimens with typical morphological traits were mounted for microscopic evaluation, and molecular confirmation was performed through DNA barcoding of the mitochondrial cytochrome c oxidase subunit I (CO1) gene, followed by sequencing and BLAST analysis.Results: Of 58 sand flies analyzed, five known species were identified: Phlebotomus argentipes (n=21; 36.2%), Sergentomyia (S.) zeylanica (n=21; 36.2%), S. indica (n=1; 1.7%), S. bailyi (n=4; 6.9%), and S. babu insularis (n=4; 6.9%). Two morphologically distinct species were also recorded. Molecular analysis confirmed the first report of Idiophlebotomus genus in Sri Lanka (n=5, 8.6%). Additionally, a novel Sergentomyia species from the Anuradhapura district was identified and described herein as S. nayanasis sp. nov.Conclusions: This study provides the first evidence of 1diophlebotomus sp. in Sri Lanka and describes S. nayanasis sp. nov., expanding the known phlebotomine fauna of the island. These results highlight the need for continued surveillance, ecological assessments, and vector competence studies to evaluate the potential epidemiological significance of newly detected sand fly species in leishmaniasis-endemic regions.

Keywords

Sand fly taxonomy / Molecular barcoding / Cryptic species / Leishmaniasis vectors

Conflict of interest statement

The authors declare that they have no competing interests.

Funding

The study was financially supported by by the Research Council, University of Kelaniya, Sri Lanka (Grant No. RP/03/04/06/02/2023).

Authors’ contributions

YK contributed to the study design, literature review, data collection, data analysis, data interpretation, and preparation of the original manuscript. NG contributed to the study conceptualization and design, supervised the research, and participated in manuscript preparation, review, and editing. DA contributed to supervision, manuscript preparation, review, and editing. CS contributed to data collection, methodology development, visualization, and manuscript drafting. NS contributed to data analysis, data interpretation, and manuscript drafting. NM contributed to supervision, funding acquisition, and critical review of the manuscript. All authors read and approved the final version of the manuscript.

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Edited by Lei Y, Pan Y, Zhang Q

Acknowledgements

We gratefully acknowledge the financial support provided by the Research Council, University of Kelaniya, Sri Lanka (Grant No. RP/03/04/06/02/2023). We also extend our sincere thanks to the field team for their assistance during the survey. Our appreciation is further extended to the residents of the study areas for their kind cooperation throughout this study.

References

[1] World Health Organization. Leishmaniasis. 2023. [Online]. Available from: https://www.who.int/news-room/fact-sheets/detail/leishmaniasis. [16 April 2026].

[2] Cecílio P, Cordeiro-da-Silva A, Oliveira F. Sand flies: Basic information on the vectors of leishmaniasis and their interactions with Leishmania parasites. Commun Biol 2022; 5(1): 305. doi: 10.1038/s42003-022-03240-z.

[3] Saini P, Kumar Shah H, Jessu M, Tom Anns ST, Amju KP. Morphological and molecular description of a new species of sandfly, Sergentomyia (Neophlebotomus) ashwanii sp. nov. (Diptera: Psychodidae) from Western Ghats, India. Asian Pac J Trop Med 2024; 17(5): 226-234.

[4] Lewis DJ, Young DG, Fairchild GB, Minter DM. Proposals for a stable classification of the Phlebotomine sandflies (Diptera: Psychodidae). Syst Entomol 1977; 2(4): 319-332.

[5] Galati EAB, de Andrade AJ, Perveen F, Loyer M, Vongphayloth K, Randrianambinintsoa FJ, et al. Phlebotomine sand flies (Diptera, Psychodidae) of the world. Parasit Vectors 2025; 18(1): 220. doi: 10.1186/ s13071-025-06748-5.

[6] Alkan C, Bichaud L, De Lamballerie X, Alten B, Gould EA, Charrel RN. Sandfly-borne phleboviruses of Eurasia and Africa: Epidemiology, genetic diversity, geographic range, control measures. Antiviral Res 2013; 100(1): 54-74.

[7] Reuter M, Harzhauser M, Piller WE. The role of sea-level and climate changes in the assembly of Sri Lankan biodiversity: A perspective from the Miocene Jaffna Limestone. Gondwana Res 2021; 91: 152-165.

[8] Bossuyt F, Meegaskumbura M, Beenaerts N, Gower DJ, Pethiyagoda R, Roelants K, et al. Local endemism within the Western Ghats-Sri Lanka biodiversity hotspot. Science 2004; 306(5695): 479-481.

[9] Dittus WPJ.. The biogeography and ecology of Sri Lankan mammals point to conservation priorities. Ceylon J Sci 2017; 46(5): 33.

[10] Gunathilaka N, Jayakody D, Wickremasinghe R. Trend analysis and spatiotemporal distribution of leishmaniasis disease incidence in Sri Lanka: A detailed review from 2009 to 2023. PLoS Negl Trop Dis 2025; 19(7): e0013158.

[11] Annandale N. Sand-flies (Phlebotomus) from Peradeniya Spolia Zeylan 1910; 7(1): 57-62.

[12] Gajapathy K, Surendran SN. Report of the presence of Phlebotomus (Phlebotomus) salehi Mesghali in Sri Lanka: A potential cutaneous leishmaniasis vector. J Natl Sci Found Sri Lanka 2012; 40(2): 168-173.

[13] Sharmintha P, Gajapathy K, Amarasinghe AAKP, Surendran SN. Genetic diversity of Phlebotomus (Euphlebotomus) argentipes species complex in Sri Lanka. Ceylon J Sci 2022; 51(3): 319-323.

[14] Gajapathy K, Tharmasegaram T, Eswaramohan T, Peries LBSL, Jayanetti R, Surendran SN. DNA barcoding of Sri Lankan phlebotomine sand flies using cytochrome c oxidase subunit I reveals the presence of cryptic species. Acta Trop 2016; 161: 1-7. doi: 10.1016/j.actatropica.2016.05.001.

[15] Ozbel Y, Sanjoba C, Alten B, Asada M, Depaquit J, Matsumoto Y, et al. Distribution and ecological aspects of sand fly (Diptera: Psychodidae) species in Sri Lanka. J Vector Ecol 2011; 36(Suppl.1): S77-S86. doi: 10.1111/J.1948-7134.2011.00115.X.

[16] Wijerathna T, Gunathilaka N. Morphological identification keys for adults of sand flies (Diptera: Psychodidae) in Sri Lanka. Parasit Vectors 2020; 13(1): 450. doi: 10.1186/s13071-020-04305-w.

[17] Tharmatha T, Gajapathy K, Ramasamy R, Surendran SN. Morphological and molecular identification of cryptic species in the Sergentomyia bailyi (Sinton, 1931) complex in Sri Lanka. Bull Entomol Res 2017; 107(1): 58-65.

[18] Gajapathy K, Peiris LB, Goodacre SL, Silva A, Jude PJ, Surendran SN. Molecular identification of potential leishmaniasis vector species within the Phlebotomus (Euphlebotomus) argentipes species complex in Sri Lanka. Parasit Vectors 2013; 6(1): 302. doi: 10.1186/1756-3305-6-302.

[19] Firouzjaie F, Vaziri VM, Zahraei-Ramazani A, Behniafar H, Badakhshan M, Spotin A, et al. Sergentomyia species identification and their screening for possible infection to Leishmania spp. in Kaleybar, East-Azerbaijan province, Iran. Vet Res Forum 2023; 14(1): 39.

[20] Dammini Premachandra WTS, Senarath DPC, De Silva MPKSK, Lalanthika Peiris BS. A study on phlebotomine sandflies (Diptera: Phlebotomidae) in Dickwella, southern Sri Lanka, an endemic focus for cutaneous leishmaniasis. Int J Trop Insect Sci 2012; 32(1): 32-38.

[21] Wijerathna T, Gunathilaka N, Rodrigo W. Genetic variation of sand flies (Diptera: Psychodidae) in Gampaha and Kurunegala districts of Sri Lanka: Complementing the morphological identification. Asian Pac J Trop Med 2022; 15(7): 322-331.

[22] Vongphayloth K, Randrianambinintsoa FJ, Lakeomany K, Phommavanh N, Pongsanarm T, Vungkyly V, et al. A study on the diversity of phlebotomine sand flies (Diptera, Psychodidae) in karstic limestone areas in Vientiane Province, Laos, with a description of two new species of Sergentomyia França and & Parrot. Parasit Vectors 2024; 17(1): 385. doi: 10.1186/S13071-024-06444-W.

[23] Lewis DJ. Phlebotomine sandflies (Diptera: Psychodidae) from the Oriental Region. Syst Entomol.1987; 12(2): 163-180.

[24] Killick-Kendrick R. . G. Young & M. A. Duncan. Memoirs of the American Entomological Institute no. 54. Gainesville, Florida, USA: Associated Publishers, 1994. 881 pp. US$ 85. ISBN 1-5666-054-2. Trans R Soc Trop Med Hyg 1995; 89(1): 125.

[25] Lewis DJ. The Phlebotomine sandflies (Diptera: Psychodidae) of the Oriental Region. Bull Br Mus Nat Hist Entomol 1978; 37: 217-343.

[26] Kalra NL, Bang YH. Manual on entomology in visceral leishmaniasis. World Health Organization: New Delhi, India, 1988. [Online]. Available from: https://scholar.google.com/scholar_lookup?title=Manuals%20on%20Entomology%20in%20Visceral%20Leishmaniasis&author=NL%20Kalra&author=YM%20Bang&publication_year=1988& [26 March 2026].

[27] Léger N, Depaquit J, Gay F. Idiophlebotomus padillarum n. sp. (Diptera Psychodidae) a new sand fly species from Palawan (Philippines). Acta Trop 2014; 132(1): 51-56.

[28] Sunantaraporn S, Somwang P, Khositharattanakool P, Unchanam I, Saenchaiban N, Wongkhut W, et al. Cave-dwelling phlebotomine sand flies (Diptera: Psychodidae: Phlebotominae) in Thailand: Population composition and pathogen detection of Bartonella and Trypanosoma. Parasit Vectors 2024; 17(1): 523. doi: 10.1186/s13071-024-06616-8.

[29] Sinh N, Vu HS, Tran VP, Tran T, Tran N, Duong T, et al. Taxonomical insights and ecology of sandfly (Diptera, Psychodidae) species in six provinces of Northern Vietnam. Parasite 2021; 28: 85. doi: 10.1051/ parasite/2021080.

[30] Boisseau RP, Bradler S, Emlen DJ. Divergence time and environmental similarity predict the strength of morphological convergence in stick and leaf insects. Proc Natl Acad Sci U S A 2025; 122(1): e2319485121. doi: 10.1073/pnas.2319485121.

[31] Cates MD, Lien JC. The Phlebotomus of Taiwan. J Med Entomol 1970; 7(5): 529-543.

[32] Soares O de SR, Rodrigues BL, Shimabukuro PHF. Accessing the sand fly diversity of Tocantins, Northern Brazil: Species delimitation using COI DNA barcoding. Biota Neotrop 2024; 24(4): e20241680.

[33] Phumee A, Sutthanont N, Chitcharoen S, Sawaswong V, Boonserm R, Ayuyoe P, et al. Sergentomyia khawi: A potential vector for Leishmania and Trypanosoma parasites affecting humans and animals and insecticide resistance status in endemic areas of Songkhla, southern Thailand. Parasit Vectors 2024; 17(1): 351. doi: 10.1186/s13071-024-06440-0.

[34] Lozano-Sardaneta YN, Mikery-Pacheco OF, Huerta H, Rojas-Soriano JE, Contreras-Ramos A. Wing geometric morphometrics is effective to separate sand fly species (Diptera, Psychodidae, Phlebotominae) related with leishmaniasis transmission in Mexico. Acta Trop 2025; 262: 107523.