Skip to main content Skip to main navigation menu Skip to site footer
Responsive image
Issue: Vol. 5768 No. 1: 9 Mar. 2026
Type: Article
Published: 2026-03-09
DOI: 10.11646/zootaxa.5768.1.3
Page range: 57-72
Abstract views: 65
PDF downloaded: 10

Larval morphology of Agnoshydrus Biström, Nilsson & Wewalka, 1997: description of A. thailandicus Okada, 2024 and phylogenetic comparison with other known Hyphydrini (Coleoptera: Adephaga, Dytiscidae)

Thailand National History Museum; National Science Museum; Pathum Thani; 12120 Thailand; Coleopterological Society of Japan. National Museum of Nature and Science; Tsukuba; 3050005 Japan
School of Natural Sciences; Laurentian University; Ramsey Lake Road; Sudbury; Ontario; CANADA
University of Buenos Aires; Faculty of Exact and Natural Sciences; Department of Biodiversity and Experimental and Applied Biology (IBBEA); Buenos Aires; Argentina
Coleoptera chaetotaxy Hydradephaga Hydroporinae larval morphology phylogeny Southeast Asia taxonomy

Abstract

The three larval instars of the Thailand endemic Agnoshydrus thailandicus Okada, 2024 are described for the first time, including a detailed chaetotaxy analysis of the cephalic capsule, head appendages, legs, last abdominal segment, and urogomphi. The phylogenetic position of Agnoshydrus Biström, Nilsson & Wewalka, 1997 is studied based on a cladistic analysis of 12 Hyphydrini species (nine genera) and 59 morphological larval characters. Although the phylogenetic relationships of Agnoshydrus within the tribe Hyphydrini remain unresolved, it seems reasonable to suggest a closer relationship with Desmopachria Babington, 1842, Hovahydrus Biström, 1982, and Microdytes J. Balfour-Browne, 1946.

 

References

  1. Alarie, Y. & Challet, G.L. (2006a) Description of the larvae of Primospes suturalis Sharp (Coleoptera: Dytiscidae: Hydroporinae) with implications for the phylogeny of the Hyphydrini. Aquatic Insects, 28, 23–30. https://doi.org/10.1080/01650420500397113
  2. Alarie, Y. & Challet, G.L. (2006b) Larval description and phylogenetic placement of the South Africa endemic genus Andex (Coleoptera: Adephaga, Dytiscidae). Annals of the Entomological Society of America, 99, 743–754. https://doi.org/10.1603/0013-8746(2006)99[743:LDAPPO]2.0.CO;2
  3. Alarie, Y. & Michat, M.C. (2007) Phylogenetic analysis of Hydroporinae (Coleoptera: Dytiscidae) based on larval morphology, with description of first instar of Laccornellus lugubris. Annals of the Entomological Society of America, 100, 655–665. https://doi.org/10.1603/0013-8746(2007)100[655:PAOHCD]2.0.CO;2
  4. Alarie, Y. & Michat, M.C. (2023) Larval chaetotaxy of world Dytiscidae (Coleoptera: Adephaga) and implications for the study of Hydradephaga. In: Yee, D.A. (Ed.), Ecology, systematics, and the natural history of predaceous diving beetles (Coleoptera: Dytiscidae) Second edition. Springer Nature Switzerland AG, Cham, pp. 17–53. https://doi.org/10.1007/978-3-031-01245-7_2
  5. Alarie, Y. & Watts, C.H.S. (2005) Description of larvae of four species of the Hyphydrus lyratus species-group (Coleoptera: Dytiscidae: Hydroporinae). Australian Journal of Entomology, 44, 244–251. https://doi.org/10.1111/j.1440-6055.2005.00481.x
  6. Alarie, Y., Wang, L.-J., Nilsson, A.N. & Spangler, P.J. (1997) Larval morphology of four genera of the tribe Hyphydrini Sharp (Coleoptera: Dytiscidae: Hydroporinae) with an analysis of their phylogenetic relationships. Annals of the Entomological Society of America, 90, 709–735. https://doi.org/10.1093/aesa/90.6.709
  7. Alarie, Y., Michat, M.C. & Challet, G.L. (2017) Larval description and phylogenetic placement of the South African endemic genera Coelhydrus Sharp and Darwinhydrus Sharp (Coleoptera: Dytiscidae: Hydroporinae: Hyphydrini). The Coleopterists Bulletin, 71, 389–401. https://doi.org/10.1649/0010-065X-71-2.389
  8. Alarie, Y., Michat, M.C., Ranarilalatiana, C. & Bergsten, J. (2022) Larval morphology of the Madagascan endemic diving beetle genus Hovahydrus Biström, 1982 (Coleoptera: Dytiscidae) and phylogenetic comparison with other known Hyphydrini. Zootaxa, 5219 (3), 227–246. https://doi.org/10.11646/zootaxa.5219.3.2
  9. Babington, C.C. (1842) Dytiscidae Darwinianae. Transactions of the Royal Society of London, 3 (1), 1–17, 1 pl.
  10. Balfour-Browne, J. (1946) Microdytes gen. nov. Dytiscidarum (Hyphydrini). Journal of the Bombay Natural History Society, 46, 106–108.
  11. Biström, O., Nilsson, A.N. & Wewalka, G. (1997) A systematic review of the tribes Hyphydrini Sharp and Pachydrini n. trib. (Coleoptera, Dytiscidae). Entomologica Fennica, 8, 57–82. https://doi.org/10.33338/ef.83921
  12. Goloboff, P.A., Farris, J.S. & Nixon, K.C. (2008) TNT, a free program for phylogenetic analysis. Cladistics, 24, 774–786. https://doi.org/10.1111/j.1096-0031.2008.00217.x
  13. Illiger, K. (1802) Aufzählung der Käfergattungen nach der Zahl der Fussglieder. Magazin für Insektenkunde, Braunschweig, 1, 285–305.
  14. Kitching, I.J., Forey, P.L., Humphries, C.J. & Williams, D.M. (1998) Cladistics, Second Edition. The theory and practice of parsimony analysis. Systematic Association Publications 11. Oxford University Press, New York, New York, 228 pp.
  15. Michat, M.C. & Archangelsky, M. (2007) Description of larvae of Desmopachria Babington (Coleoptera: Dytiscidae: Hydroporinae): the D. vicina Sharp species group. The Coleopterists Bulletin, 61, 264–276. https://doi.org/10.1649/0010-065X(2007)61[264:DOLODB]2.0.CO;2
  16. Miller, K.B. & Bergsten, J. (2016) Diving beetles of the world. Systematics and biology of the Dytiscidae. Johns Hopkins University Press, Baltimore, Maryland, 320 pp.
  17. Miller, K.B. & Bergsten, J. (2023) The phylogeny and classification of predaceous diving beetles. In: Yee, D.A. (Ed.), Ecology, Systematics, and the Natural History of Predaceous Diving Beetles (Coleoptera: Dytiscidae) Second Edition. Springer Nature Switzerland AG, Cham, pp. 55–185. https://doi.org/10.1007/978-3-031-01245-7_3
  18. Miller, K.B., Wolfe, G.W. & Biström, O. (2006) The phylogeny of the Hydroporinae and classification of the genus Peschetius Guignot (1942) (Coleoptera: Dytiscidae). Insect Systematics & Evolution, 37, 1–23. https://doi.org/10.1163/187631206788838617
  19. Okada, R. (2024) A review of Agnoshydrus Biström, Nilsson & Wewalka, 1997 (Coleoptera: Dytiscidae: Hyphydrini), with descriptions of two new species from Thailand. Zootaxa, 5428 (3), 440–448. https://doi.org/10.11646/zootaxa.5428.3.7
  20. Ribera, I. & Balke, M. (2007) Recognition of a species-poor geographically restricted but morphologically diverse Cape lineage of diving beetles (Coleoptera: Dytiscidae: Hyphydrini). Journal of Biogeography, 34, 1220–1232. https://doi.org/10.1111/j.1365-2699.2007.01694.x
  21. Roughley, R.E. & Wolfe, G.W. (1987) Laccornellus (Coleoptera: Dytiscidae). A new hydroporine genus from austral South America. Canadian Journal of Zoology, 65, 1346–1353. https://doi.org/10.1139/z87-214
  22. Sharp, D. (1882) On aquatic carnivorous Coleoptera or Dytiscidae. The Scientific Transactions of the Royal Dublin Society, Series 2, 2, 179–1003, pls. 7–18.
  23. Wewalka, G. (1999) Synopsis of Agnoshydrus Biström, Nilsson & Wewalka with description of a new species (Coleoptera: Dytiscidae). Koleopterologische Rundschau, 69, 25–28.
  24. Wewalka, G. & Wang, L.-J. (2007) Three new species of the genus Agnoshydrus Biström, Nilsson & Wewalka from Taiwan and Borneo (Coleoptera: Dytiscidae). Zeitschrift der Arbeitsgemeinschaft Österreichischer Entomologen, 59, 1–8.
  25. Wewalka, G., Balke, M. & Hendrich, L. (2001) Anginopachria, a new genus for an enigmatic species previously assigned to Allopachria (Coleoptera: Dytiscidae). Entomological Problems, 32, 91–92.
  26. Zimmermann, A. (1924) Revision der Colymbetinen-Gattung Lancetes Sharp (Col.). Wiener Entomologische Zeitung, 41, 89–99.

How to Cite

Okada, R., Alarie, Y. & Michat, M.C. (2026) Larval morphology of Agnoshydrus Biström, Nilsson & Wewalka, 1997: description of A. thailandicus Okada, 2024 and phylogenetic comparison with other known Hyphydrini (Coleoptera: Adephaga, Dytiscidae). Zootaxa, 5768 (1), 57–72. https://doi.org/10.11646/zootaxa.5768.1.3