水生甲蟲是淡水中的常見昆蟲，具有抑制病媒蚊的能力。然而，水生甲蟲正在逐漸消失，因此在台灣中部水稻田中對水生甲蟲進行調查。採集期間為2019年，計有3科25種，並比較近海地區和內陸地區，共採集1098隻水生甲蟲，研究結果表明在台灣中部地區的近海地區的辛普森多樣性指數和物種數均優於內陸地區，並在台灣首次記錄到Hydrochara affinis (Sharp, 1873)。另外，基於採集的材料和博物館標本，修訂台灣的麗陽牙蟲屬Helochares Mulsant, 1844。共有6個物種: H. anchoralis Sharp, 1890、H. atropiceus Regimbart, 1903、H. lentus Sharp, 1890、H. neglectus (Hope, 1845)、H. pallens MacLeay, 1825和H. sauteri Orchymont, 1943。提供台灣分布圖和該屬的檢索表，並根據日本與那國島的標本，證實H. uenoi Matsui, 1995為H. sauteri Orchymont, 1943的同物異名。此外根據台灣採集的標本，描述了H. atropiceus Regimbart, 1903的幼蟲形態和頭部特徵。

Aquatic beetles are common insects in freshwater and have the ability to suppress vector mosquitoes. However, the aquatic beetles are gradually disappearing. Therefore, aquatic beetles in the rice fields of middle of Taiwan. The collection period was 2019, total 25 species belonging to 3 families. We compare the near sea area and the inland area. In total 1098 aquatic beetles individuals were collected, the results showed that the Simpson’s index and species number of near sea area are better than that of inland area in the middle of Taiwan, and first records Hydrochara affinis (Sharp, 1873) from Taiwan. In addition, the water scavenger beetle genus Helochares Mulsant, 1844 of Taiwan is reviewed based on freshly collected material and museum specimens. 6 species are recognized: H. anchoralis Sharp, 1890, H. atropiceus Regimbart, 1903, H. lentus Sharp, 1890, H. neglectus (Hope, 1845), H. pallens MacLeay, 1825 and H. sauteri Orchymont, 1943. A distribution map and key to Taiwanese species of the genus are provided. Based on the specimen of Yonaguni Island, Japan, confirmed H. uenoi Matsui, 1995, syn. nov. is synonymized with H. sauteri Orchymont, 1943. The morphology and head chaetotaxy of the larvae of H. atropiceus Regimbart, 1903 are described based on specimens collected in Taiwan.

Contents
中文摘要 I
Abstract II
Acknowledgements III
Contents IV
List of Tables VI
List of Figures VII
1. Introduction 1
1-1 Motivation of research 1
1-2 Purpose of research 2
2. Literature Review 3
2-1 Survey of aquatic beetles in Taiwan 3
2-2 Taxonomy of Helochares Mulsant, 1844 4
3. Material and methods 6
3-1 Conceptual Framework 6
3-2 Study area 8
3-3 Data analysis 10
3-4 Specimen preparation and photographs 11
4. Results and discussion 14
4-1 Aquatic Coleoptera in rice field in the middle of Taiwan 14
4-2 Diversity of aquatic beetles in inland and near sea areas 16
4-3 Taxonomy of the Helochares Mulsant, 1844 in Taiwan 19
Genus Helochares Mulsant, 1844 19
Key to Taiwanese species of genus Helochares Mulsant 19
Helochares (s. str) atropiceus Regimbart, 1903 22
Helochares (s. str.) pallens MacLeay, 1825 32
Helochares (Hydrobaticus) anchoralis Sharp, 1890 34
Helochares (Hydrobaticus) lentus Sharp, 1890 35
Helochares (Hydrobaticus) neglectus (Hope, 1845) 37
Helochares (Hydrobaticus) sauteri Orchymont, 1943 38
5. Conclusion 48
6. References in English 49
7. References in Chinese 55
8. Appendix 58

List of Tables
Table 2-1. Literatures on the survey of aquatic beetles in the standing water in Taiwan. 3
Table 2-2. State of knowledge of the larvae of the Taiwan species of Helochares. L1, L2, L3 – larva of first, second, third instar; L? – larval instar unknown. 5
Table 3-1. Location of the rice fields. 9
Table 4-1. Aquatic beetles in rice field from the middle of Taiwan. 15

List of Figures
Figure 3-1. Conceptual Framework. 7
Figure 3-2. Study sites (St. 1–St. 19) in middle of Taiwan 8
Figure 3-3. fishing nets. 10
Figure 3-4. Material: (A) alcohol; (B) KOH; (C) heater; (D) microscope. 13
Figure 4-3. Environmental changes habitat for aquatic beetles in between Taichung City and Changhua County, (A) before urban development, (B) after urban development. Slash: Range of habitat of aquatic beetles in standing waters, parallelogram: Fish pond. 18
Figure 4-3. Egg case of Helochares pallens (A) dorsal view; (B) ventral view; (C) female carry egg case. 21
Figure 4-4. Helochares (s. str) atropiceus Regimbart, 1903: (A–B) habitus of adult: (A) dorsal; (B) ventral; (C) adult carrying egg case; (D–G) larvae of H. atropiceus: (D) first instar; (E) second instar; (F) third instar (G) anterior margin of third instar. 25
Figure 4-5. Helochares atropiceus, first instar, head capsule. (A) dorsal view; (B) ventral view; (C) anterior margin, dorsal view. 26
Figure 4-6. Helochares atropiceus, first instar. (A) antenna, dorsal view; (B–C) maxilla, dorsal view and ventral views; (D–E) labium, dorsal and ventral views; (F–G) mandible, left and right. 27
Figure 4-7. Helochares atropiceus, second instar, head capsule. (A) dorsal view; (B) ventral view; (C) anterior margin, dorsal view. 28
Figure 4-8. Helochares atropiceus, second instar. (A) antenna, dorsal view; (B–C) – maxilla, dorsal view and ventral views; (D–E) labium, dorsal and ventral views; (F–G) mandible, left and right. 29
Figure 4-9. Helochares atropiceus, third instar, head capsule. (A) dorsal view; (B) ventral view; (C) anterior margin, dorsal view. 30
Figure 4-10. Helochares atropiceus, third instar. (A) antenna, dorsal view; (B–C) maxilla, dorsal view and ventral views; (D–E) labium, dorsal and ventral views; (F–G) mandible, left and right; (H) leg. 31
Figure 4-11. Habitus of Helochares species (A, C, E, G, I: habitus of dorsal view; B, D, F, H, J: habitus of ventral view; K–L: pronotum): (A–B, K–L) H. pallens; (C–D) H. anchoralis; (E–F) H. lentus; (G–H, L) H. neglectus; (I–J, M) H. sauteri. Scale size 1mm. 42
Figure 4-12. Elytra of Taiwanese Helochares species: (A) H. atropiceus; (B) H. pallens; (C) H. anchoralis; (D) H. lentus; (E) H. neglectus; (F) H. sauteri. 43
Figure 4-13. Male genitalia of Taiwanese Helochares species (A, C, E, G, I, K: dorsal view; B, D, F, H, J, L: lateral view): (A, B) H. atropiceus; (C, D) H. pallens; (E, F) H. anchoralis; (G, H) H. lentus; (I, J) H. neglectus; (K, L) H. sauteri. 44
Figure 4-14. Type specimens of Helochares species (A, E, I: habitus; B, F, J: abdomen and aedaegus; C–D, G–H, K: labels): (A–D) H. anchoralis; (E–H) H. lentus; (I–K) H. sauteri. Scale size 2mm. 45
Figure 4-15. Habitat of Helochares species: (A) Hsinchu County, Zhudong Township, habitat for H. anchoralis and H. pallens; (B) Hsinchu County, Beipu Township, habitat for H. atropiceus; (C) Tainan City, Baihe District, habitat for H. neglectus; (D) Taichung City, Wufeng District, habitat for H. sauteri. 46
Figure 4-16. Map of Taiwan showing distribution of species of the Helochares species. 47
Figure 8-1. Photos of sample stations. (A) Site 1; (B) Site 2; (C) Site 3; (D) Site 4; (E) Site 5; (F) Site 6. 58
Figure 8-2. Photos of sample stations. (A) Site 7; (B) Site 8; (C) Site 9; (D) Site 10; (E) Site 11; (F) Site 12. 59
Figure 8-3. Photos of sample stations. (A) Site 13; (B) Site 14; (C) Site 15; (D) Site 16; (E) Site 17; (F) Site 18; (G) Site 19. 60

Bellini, R., Pederzani F., Pilani R., Veronesi R. and Maini S., “Hydroglyphus pusillus (Fabricius) (Coleoptera: Dytiscidae): its role as a mosquito larvae predator in rice fields,” Bollettino dell’Istituto di Entomologia ‘G. Grandi’dell’Universitadi Bologna 54, pp.155-163(2000).
Fikáček, M., Liang, W.-R., Hsiao, Y., Jia, F.-L. and Vondráček, D., “Biology and morphology of immature stages of banana-associated Protosternum beetles, with comments on the status of Taiwanese endemic P. abnormale (Coleoptera: Hydrophilidae),” Zoologischer Anzeiger, Vol. 277, pp.85-100(2018).
Fikáček, M. and Liu, H.-C., “A review of Thysanarthria with description of seven new species and comments on its relationship to Chaetarthria (Hydrophilidae: Chaetarthriini),” Acta Entomologica Musei Nationalis Pragae, Vol. 59, No. 1, pp.229-252(2019).
Hansen, M., World Catalogue of Insects. volume 2. Hydrophiloidea (s. str.) (Coleoptera), Apollo Books, Stenstrup, pp. 416(1999).
Hayashi, M., “Distributional records and ecological notes on aquatic Coleoptera of Shimane prefecture, Part II,” Bulletin of Hoshizaki Green Foundation, Vol. 11, pp.61–91 (2008).
Hayashi, M., “Aquatic Hydrophilidae of Shimane prefecture,” Bulletin of Hoshizaki Green Foundation, Vol.12, pp. 87–121(2009).
Hebauer, F., “Neues zu den Acidocerina Hansen (Helocharae d’Orchymont) der indomalaiischen Region (Coleoptera, Hydrophilidae),” Acta Coleopterologica, Vol.11, No. 3, pp.3-14(1995).
Hebauer F., “Synopsis der afrikanischen Arten der Gattung Helochares Mulsant (Coleoptera: Hydrophilidae),” Acta coleopterologica, Vol. 12. No. 2, pp.3-38(1996).
Hebauer F., “Six new species of the genus Helochares Mulsant, 1844, subgenus Hydrobaticus Macyleay, 1871 from Africa and Asia (Coleoptera: Hydrophilidae),” Acta coleopterologica, Vol. 14, No. 2, pp.41-46(1998).
Hebauer, F. and Wang, J., “New species of the genus Oocyclus Sharp, 1882 from India, Sri Lanka and Taiwan with a key to all known species (Coleoptera: Hydrophilidae),” Acta Coleopterologica, Vol. 14, No. 37-46(1998).
Hebauer F., “New Hydrophilidae of the Old World (Coleoptera: Hydrophilidae),” Acta coleopterologica, Vol. 18, No. 3, pp.3-24(2002).
Hebauer F., “Checklist of the Malgasy Helochares with description of a new species (Coleoptera: Hydrophilidae),” Acta coleopterologica, Vol. 19, No. 1, pp.67-69(2003).
Jia, F.-L. and Tang Y.-D., “A revision of the Chinese Helochares (s. str.) Mulsant, 1844 (Coleoptera, Hydrophilidae),” European Journal of Taxonomy, Vol. 438, pp.1–27(2018).
Kim, J.-H, Chung, H.Y., Kim, S.H. and Kim, J.G. “The influence of water characteristics on the aquatic insect and plant assemblage in small irrigation ponds in Civilian Control Zone,” Journal of Wetlands Research, Vol. 18, No. 4, pp. 331-341(2016).
Komarek, A., “Taxonomic revision of Anacaena Thomson, 1859 VIII. Taiwan (Coleoptera: Hydrophilidae),” Koleopterologische Rundschau, Vol. 81, pp.229-236(2011)
Liao, W., Venn, S and Niemelä, J., “Environmental determinants of diving beetle assemblages (Coleoptera: Dytiscidae) in an urban landscape,” Biodivers Conserv, Vol. 29, pp.2343-2359 (2020).
Liu, H.-C., Hu, F.-S. and Fikáček, M., “Review of the genus Coelostoma of Taiwan with description of a new species (Coleoptera: Hydrophilidae),” Acta Entomologica Musei Nationalis Pragae, Vol. 60, No. 1, pp.155-162 (2020).
Magurran, A. E., Ecological diversity and its measurement, Princeton Univ. Press, Princeton, New Jersey, pp.179(1988).
Matsui, E., “A new Species of the Genus Helochares (Coleoptera, Hydrophilidae) from Japan, with a Key to the Japanese Species of the Subgenus Hydrovalicus,” Special Bulletin of the Japanese Society of Colcopterology, Vol. 4, pp.317-322(1995).
Miller, K. B., “Revision of the genus Eretes Laporte, 1833 (Coleoptera: Dytiscidae),” Aquatic Insects, Vol. 24, No. 4, pp. 247-272(2002).
Minoshima, Y., and Hayashi M., “Larvalmorphology of the Japanese species of the tribesAcidocerini, Hydrobiusini and Hydrophilini (Coleoptera: Hydrophilidae,” Acta EntomologicaMusei Nationalis Pragae, Vol. 51 (supplementum), pp.1-118(2011).
Mori, M., and Kitayama, A., “Dytiscoidea of Japan, revised ed”. Bun-ichi Sogo Shuppan, Tokyo, Japan, pp. 231(2002).
Mulsant, E., “Histoire naturelle des coléopteres de France. Palpicornies”. Paris, L. Maison, Lyon, Ch. Savy Jeune, pp. 196 (1844).
Nasserzadeh, H. and Komarek, A., “Taxonomic revision of the water scavenger beetle genus Sternolophus Solier, 1834 (Coleoptera: Hydrophilidae),” Zootaxa, Vol. 4282, No. 2, pp.201-254(2017).
Nitta, R. and Yoshitomi, H., “Revision of the Japanese species of the genus Berosus (Coleoptera, Hydrophilidae),” Sayabane, No. 7, pp. 18-31(2012).
Ohba, S.-Y., and Masahiro T., “Predatory ability of adult diving beetles on the Japanese encephalitis vector Culex tritaeniorhynchus,” Journal of the American Mosquito Control Association, Vol. 26, No. 1, pp.32-36 (2010).
Orchymont, A., “Contribution a l'ctudc des Palpicornia XIV,” - Bulletin et Annales dc la Soeiete Entomologique dc Bclgique, Vol. 80, pp.157-197(1940).
Przewoźny, M., “Catalogue of Palearctic Hydrophiloidea (Coleoptera),” Internet version, pp.1-60 (2020).
Short A. E. Z. and Fikáček M., “World catalogue of the Hydrophiloidea (Coleoptera): additions and corrections II (2006–2010),” Acta Entomologica Musei Nationalis Pragae, Vol. 51, No. 1, pp.83–122(2011).
Short A. E. Z., Systematics of aquatic beetles (Coleoptera): current state and future directions. (Electronic article). Systematic Entomology, vol. 43, pp. 1-18(2017)
Short A. E. Z. and Giron J. C., “Review of the Helochares (Hydrobaticus) MacLeay of the New World (Coleoptera: Hydrophilidae: Acidocerinae)” Zootaxa, Vol. 4407, No. 1, pp.29-50(2018).
Smetana, A., “Revision of the genus Hydrochara (Coleoptera: Hydrophilidae),” The Memoirs of the Entomological Society of Canada, Vol. 112, No. 111, 1–100(1980).
Ueng, Y.-T., Wang W.-C. and Wang J.-P., “A New Species of water scavenger beetle, Berosus salinus, n. sp. from Taiwan and China (Coleoptera: Hydrophilidae),” Journal of the National Taiwan Museum, Vol. 59, No. 2, pp.61- 68(2006).
Ueng, Y.-T., Wang W.-C. and Wang J.-P., “Berosus tayouanus, a replacement name for Berosus salinus Ueng et aI. (Coleoptera: Hydrophilidae),” Journal of the National Taiwan Museum, Vol. 60, No. 2, pp.87-88(2007).
Yano, K., Chu Y.-I., Resma P. W. and Sato M., “Faunal and biological studies on the insects of paddy fields in Asia. XII. Aquatic Coleoptera from Taiwan and the Philippine,” Formosan Entomologist, Vol. 3, No. 2, pp.103-118(1983)
邱思叡，「北海岸農耕水梯田與休耕水梯田水棲昆蟲群聚結構之研究」，臺北市立大學地球環境暨生物資源學系含環境教育與資源碩士班，臺北(2017年)。
朱本勳、黃耀德、管立豪、吳麗娟、蕭文鳳，台灣南部及金門農田與魚塭之水棲昆蟲調查，台灣昆蟲，第36卷，第124-137頁(2017年)。
范姜俊承，「蘭嶼紅頭溪水生及半水生昆蟲多樣性與昆蟲多樣性研究之評論」，碩士論文，國立中興大學昆蟲學系，臺中(2005年)。
何鎧光、徐世傑，臺北區新店溪水生昆蟲之研究，臺灣省立博物館科學年刊，第二十卷，第1-49頁(1977年)。
鄭明倫、楊平世，「玉山國家公園東埔－八通關、塔塔加、南橫沿線、南安地區水棲甲蟲相調查」，內政部營建署陽明山國家公園管理處，臺北(1993年)。
李仁耀，「不穩定水域水棲昆蟲群聚結構」，碩士論文，國立花蓮教育大學生物資源與科技研究所，花蓮(2009年)。
林怡萱，「太魯閣國家公園砂卡礑溪水棲昆蟲群聚結構研究」，碩士論文，國立花蓮教育大學生態與環境教育研究所，花蓮(2008年)。
林斯正、謝森和、楊平世，合歡山池沼群底棲大型無脊椎動物之分布，台灣昆蟲，第26卷，第3，第261-272頁(2006年)。
林斯正、黃朝慶、邱錦和、楊平世、謝森和，台灣東北部山區湖沼水質與底棲無脊椎動物群聚之關係，台灣生物多樣性研究，第十三卷，第一期，第37-51頁(2011年)。
廖勖凱，「水梯田水棲昆蟲群聚結構與水生植物密度關係-以新北市貢寮區為例」，碩士論文，臺北市立大學地球環境暨生物資源學系含環境教育與資源碩士班，臺北(2016年)。
林斯正、黃朝慶、邱錦和、林宗以、楊平世、謝森和，台灣南部嘉明湖底質與底棲無脊椎動物初探。台灣生物多樣性研究，第十三卷，第二期，167-173頁(2011年)。
王齡國，「烏溪之水棲昆蟲資源調查及水質監測研究」，碩士論文，國立嘉義大學生物資源學系，嘉義(2007年)。
楊平世、黃國靖、謝森和，北勢溪之水棲昆蟲資源及生態研究(I) 水棲昆蟲相及其相關生態，台灣昆蟲，第10卷，第209-224頁(1990年)。