taxonID	type	description	language	source
03DC697BFF8BFFDC77CAFF77FBCEFA0D.taxon	description	(Figs. 1 A, 3 A – B)	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8BFFDC77CAFF77FBCEFA0D.taxon	materials_examined	Material examined. INDONESIA: South Sulawesi Province: Gowa Distr., 6 km E Malino, Gn. Bawakareng Area, border of gardens and mixed forest nr Lembanna camp, 5 ° 15.4 ' S 119 ° 54.5 ' E, 1520 m a. s. l., 11 – 13. II. 2015, leg. J. Hájek & J. Sumpich, 1 female (GTGC). SOLOMON ISLANDS: Guadalcanal: ca. 3.5 km SE of Barana vill. 9 ° 29.8 ' S 159 ° 59.5 ' E, 190 m a. s. l., 24. XI – 14. XII. 2013, leg. J. Hájek, 1 female (GTGC).	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8BFFDC77CAFF77FBCEFA0D.taxon	diagnosis	Diagnosis. Male: Aedeagus (after Svensson 1991; Mazzoldi 2010) with median lobe slightly shorter than parameres, strongly attenuate in apical 1 / 2, apex bifid, lateral margin of parameres weakly curved, apex rounded (Fig. 3 A). Female (Fig. 1 A): Size: 4.5 mm. Body form oval, strongly convex in lateral view; pronotum and elytral margins darkly colored, pronotum with median transverse depression, dorsal surface fairly evenly covered with microreticulation consisting of polyhedric meshes; pronotum and elytra laterally with bronzy-metallic sheen; striae I – XI evident with distinct, widely spaced punctures, all elytral striae non-sulcate; all intervals similarly convex; elytral apex truncate, without border, epipleural angle indistinct; metanepisternal ostiole small. Gonocoxae as in Fig. 3 B. Differential diagnosis. The species is easily distinguished from all other Gyrinus known from Southeast Asia by its microreticulate dorsal surface and the lateral sides of pronotum and elytra having a distinct bronzy-metallic sheen.	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8BFFDC77CAFF77FBCEFA0D.taxon	distribution	Distribution. This species is known from the Malay Peninsula, throughout Indonesia, Luzon of the Philippines, New Guinea and the Bismarck Archipelago (Ochs 1927, 1930, 1955; Brinck 1976; Svensson 1991; Freitag et al. 2016), and possibly also from Sri Lanka (Svensson 1991). Habitat. Gyrinus sericeolimbatus occurs in a wide variety of habitats from large lakes to streams at both low and high elevation (Svensson 1991).	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8BFFDC77CAFF77FBCEFA0D.taxon	discussion	Discussion. The first report of a species of Gyrinus in Thailand was of G. sericeolimbatus (Ochs 1927, 1930) found in a stream at Khao Luang National Park, Nakhon Si Thammarat Province at an elevation of about 609 m a. s. l. For this study, a large number of aquatic insects were collected intensively at the Nakhon Si Thammarat Mountain Range, but G. sericeolimbatus was not found. However, we did not collect within Khao Luang National Park where G. sericeolimbatus has been reported. Therefore, this species may occur at only a few localities within the Nakhon Si Thammarat Mountain Range. More generally, G. sericeolimbatus exhibits substantial variation in both habitat and morphology across its wide geographic distribution with a couple of closely related species in New Guinea (i. e., G. toxopeusi Ochs 1955 and G. brincki Svennson 1991), and one subspecies (G. s. wegneri Ochs, 1959) in Timor. These taxa were distinguished from G. s. sericeolimbatus based on variation in dorsal microreticulation, extent of the brassy lateral sheen of the elytra, dorsal convexity, and width of the male protarsus (Ochs 1955, 1959; Svensson 1991). The specimens of G. sericeolimbatus that we examined had a fairly complete covering of microreticulation consisting of polyhedric meshes, which would qualify as a four on the reticulation index established by Svensson 1991. Sampling for phylogenetic analysis of this highly variable and widely distributed species complex across its range would be beneficial for both phylogeographic and species delimitation purposes.	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8BFFDB77CAF9F3FC9DF828.taxon	description	(Figs. 1 B, 2, 3 C – E, 7 A – B, 8 A)	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8BFFDB77CAF9F3FC9DF828.taxon	materials_examined	Material examined. THAILAND: Chiang Mai Province: Doi Inthanon Natl. Park, Mae Klang at Ban Khun Klang, 18 ° 31.259 ' N 98 ° 31.310 ' E, 1296 m a. s. l., 18. V. 2004, leg. T. Prommi, A. Vitheepradit, P. Laudee & P. Thamasenanupap, L- 694, 3 males, 9 females (UMC); same locality except for, Pha Dum Waterfall, 18 ° 36 ' N 98 ° 31 ' E, 1379 m a. s. l., 3. V. 2003, leg. UMC & CMU teams, L- 499, 3 males, 2 females (UMC); same locality except for, Siriphum Waterfall (lowest level), 18 ° 32 ' N 98 ° 31 ' E, 1460 m a. s. l., 21. III. 2002, leg. R. W. Sites, A. Vitheepradit & K. Kirawanich, L- 315, 4 males, 3 females (UMC); same locality except for, 9. V. 2002, leg. UMC & CMU teams, L- 401, 3 males (UMC); same locality except for, stream from Huai Sai Luang Waterfall, 18 ° 31 ' N 98 ° 27 ' E, 1060 m a. s. l., 8. V. 2002, leg. UMC & CMU teams, L- 396, 27 males, 27 females (UMC); Doi Suthep Natl. Park, Monthathan Waterfall, 18 ° 49 ' N 98 ° 55 ' E, 700 m a. s. l., 11. I. 2003, leg. CMU Team, 1 male (UMC); same locality except for, 14. II. 2003, leg. CMU Team, 1 male (UMC); Pond at Ban Buak Thoei, Pong Yaeng Subdistrict, Mae Rim District, 18 ° 53 ' 30.2 " N 98 ° 47 ' 36.5 " E, 1153 m a. s. l., 29. IV. 2018, leg. B. Suksai, S. Kullasoot, C. Yatfung & P. Sapewisut, 2 males, 1 female (THNHM). Kanchanaburi Province: Thong Pha Phum Natl. Park, Huay Ka Yeang Stream, Hin Dat Subdistrict, Thong Pha Phum District, 14 ° 33 ' 18.0 '' N 98 ° 35 ' 51.8 '' E, 270 m a. s. l., 25. II. 2002, leg. S. Saeheag, 2 males (KKU, THNHM), 1 female (THNHM). Loei Province: Phu Hin Rongkla Natl. Park, Man Daeng Noi at trail, 16 ° 57 ' N 101 ° 03 ' E, 1600 m a. s. l., 5. V. 2003, leg. N. Changthong, 20 males, 18 females (UMC); same locality except for, 1340 m a. s. l., 6. V. 2003, leg. A. Vitheepradit, T. Prommi & M. L. Ferro, L- 504, 10 males, 16 females (UMC); Phu Kradueng Natl. Park, stream from Tham Yai Waterfall, Si Than Subdistrict, Phu Kradueng District, 16 ° 52 ' 59.9 " N 101 ° 46 ' 46.4 " E, 1197 m a. s. l., 7. XII. 2010, leg. N. Sangpradub, 1 female (KKU); same locality except for, Tham Sor Nuo Waterfall, Si Than Subdistrict, Phu Kradueng District, 16 ° 52 ' 36.2 " N 101 ° 44 ' 48.2 " E, 1234 m a. s. l., 8. III. 2011, leg. N. Sangpradub, 1 male, 1 female (THNHM); same locality except for, Wang Kwang Waterfall, Si Than Subdistrict, Phu Kradueng District, 16 ° 53 ' 29.5 " N 101 ° 47 ' 03.5 " E, 1221 m a. s. l., 6. III. 2011, leg. N. Sangpradub, 2 females (KKU). Nan Province: Doi Phuka Natl. Park, Ton Thong Waterfall, 19 ° 12 ' N 101 ° 04 ' E, 900 m a. s. l., 21. IV. 2003, leg. A. Vitheepradit, T. Prommi & K. Setaphan, L- 472, 4 males, 1 female (UMC); stream at Khun Sathan Natl. Park, Ban Mueng Li, Mueng Li Subdistrict, Na Muen District, 18 ° 15 ' 08.4 " N 100 ° 29 ' 35.8 " E, 786 m a. s. l., 29. V. 2017, leg. P. Sapewisut, 1 male, 1 female (THNHM). Phitsanulok Province: Phu Hin Rongkla Natl. Park, stream btw Rd 2113 and Man Daeng Waterfall, 12. VI. 1998, leg. R. W. Sites & K. B. Simpson, L- 187, 22 males, 17 females (UMC); same locality except for, Waterwheel falls and stream, 16 ° 59 ' N 101 ° 00 ' E, 1280 m a. s. l., 10. II. 2003, leg. CMU Team, 6 males, 4 females (UMC); same locality except for, 6. V. 2003, leg. A. Vitheepradit, T. Prommi & M. L. Ferro, L- 506, 2 males, 3 females (UMC); same locality except for, 12. VII. 2003, leg. N. Changthong, 1 male, 3 females (UMC); Thung Salaeng Luang Natl. Park, Tum Din Stream, Ban Mung Subdistrict, Noen Maprang District, 16 ° 29 ' 07.5 " N 100 ° 48 ' 31.2 " E, 894 m a. s. l., 23. III. 2011, leg. N. Sangpradub, 1 male, 1 female (KKU).	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8BFFDB77CAF9F3FC9DF828.taxon	diagnosis	Diagnosis. Male (Fig. 1 B): Size: 4.0 – 5.0 mm. Body form oval, strongly convex in lateral view; pronotum and elytral margins darkly colored, pronotum with median transverse depression (Fig. 2 A), dorsal surface strongly iridescent, without evident microreticulation; pronotum and elytra laterally without bronzy-metallic sheen; striae I – XI evident with distinct, widely spaced punctures, striae VI – X strongly sulcate (Fig. 2 B); elytral intervals VII – X convex; elytral apex truncate (Figs. 1 B, 2 B – C), without border (Fig. 2 C), epipleural angle indistinct; metaepisternal ostiole small; aedeagus with median lobe slightly shorter than parameres, apical half of median lobe broader in width than single paramere, apex weakly triangular, lateral margin of parameres weakly curved, apex rounded (Figs. 3 C – D). Female: Similar to male but with a more oval body form; gonocoxae as in Fig. 3 E. Differential diagnosis. Among the Old World Gyrinus, G. smaragdinus is closest to G. ignitus Régimbart, 1895, a Malagasy endemic species. The only other species of Gyrinus recorded from Thailand is G. sericeolimbatus. G. smaragdinus can be distinguished from G. sericeolimbatus by its iridescent appearance and strongly sulcate lateral elytral setriae.	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8BFFDB77CAF9F3FC9DF828.taxon	distribution	Distribution. This species is known from northeastern India, to Myanmar, Yunnan Province of southern China, and northern Vietnam (Ochs 1930; Vazirani 1972, 1984; Mazzoldi 1995). It is here recorded for the first time in Thailand. Habitat. We found G. smaragdinus most often on stagnant water of montane streams and ponds at high elevation, ranging from 700 to 1600 m a. s. l. (Figs. 7 A – B). Only a few specimens were found in a stream at a low elevation (270 m a. s. l.).	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8BFFDB77CAF9F3FC9DF828.taxon	discussion	Discussion. G. smaragdinus is the only species of Gyrinus that we encountered during our sampling in the northern, western and northeastern regions of Thailand (Fig. 8 A). The first author found this beetle in a pond surrounded by land with both agricultural use and intact forest.	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8FFFD877CAFF3FFECDF8BE.taxon	description	(Figs. 1 C – D, 4 A, 5 A – E, 7 C, 8 A)	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8FFFD877CAFF3FFECDF8BE.taxon	materials_examined	Material examined. THAILAND: Chiang Mai Province: Doi Inthanon Natl. Park, Mae Klang Waterfall, 18 ° 29 ' N 98 ° 40 ' E, 415 m a. s. l., 3. IV. 2002, leg. CMU Team, 1 female (GTGC). Khon Kaen Province: Chum Pae District, 16 ° 34.585 ' N 102 ° 01.668 ' E, 415 m a. s. l., 3. V. 2004, leg. A. Vitheepradit, L- 660, 1 female (GTGC). Nakhon Ratchasima Province: Sakaerat Environmental Research Station, Bon weir, U-dom Sap Subdistrict, Wang Nam Khiao District, 14 ° 29 ' 49.2 " N 101 ° 54 ' 55.5 " E, 472 m a. s. l., 22. II. 2014, leg. B. Suksai, 1 male (KKU); same locality except for, 29. III. 2018, leg. P. Chanteenok, 1 female (KKU); same locality except for, 8. IV. 2018, leg. B. Suksai, O. Pornsophon, T. Jantaranakee & S. Phengsalung, 2 males, 2 females (THNHM). Phang Nga Province: Ban Bang Klag Klang, Koag Kien Subdistrict, Takua Pa District, 8 ° 52.469 ' N 98 ° 22.679 ' E, 17 m a. s. l., 4. I. 2006, leg. A. Vitheepradit, R. W. Sites & T. Prommi, L- 881, 1 male (UMC). Prachuap Khiri Khan Province: Ban Fah Pa Tarn, Hua Hin District, 12 ° 31.810 ' N 99 ° 32.062 ' E, 149 m a. s. l., 28. V. 2004, leg. A. Vitheepradit & T. Prommi, L- 723, 1 male (UMC); same locality except for, Bue Sawan Stream, Huay Yang Subdistrict, Thap Sakae District, 11 ° 40 ' 29.4 " N 99 ° 36 ' 02.4 " E, 208 m a. s. l., 23. V. 2017, leg. B. Suksai & C. Yatfung, 1 female (THNHM).	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8FFFD877CAFF3FFECDF8BE.taxon	diagnosis	Diagnosis. Male (Fig. 1 C): Size: 7.6 – 8.2 mm. Body form oval; apex of flagellomere VI darkly colored; elytral apices obliquely truncate with epipleural spines and serrations present (Figs. 1 C, 5 A); lateral marginal of pronotum and elytron black to brown; protrochanter apically with patch of thick setae on ventral surface (Fig. 4 A); profemur without sub-apicoventral tooth; protibia wedge-shaped; venter black, epipleura brownish; aedeagus (Figs. 5 C – D) with median lobe slightly shorter than parameres, swollen in basal 1 / 9, strongly narrowed after basal 1 / 9, apex with tip strongly pointed, weakly curved ventrally in lateral view. Female (Fig. 1 D): Similar to male except for size: 8.1 – 8.2 mm; elytral apices truncate without epipleural spines (Figs. 1 D, 5 B), protrochanter apically without patch of thick setae on ventral surface; gonocoxae (Fig. 5 E) elongate, lateral margin expanded and weakly rounded, apex nearly straight. Differential diagnosis. Dineutus australis is closest to D. unidentatus, which also is found in Thailand, and can be distinguished from all other species of Dineutus in this country by the protrochanter of the male having a distinct patch of setae. Both sexes of D. australis can be distinguished from those of D. unidentatus by the oval body form and larger size, whereas in D. unidentatus the body is narrowly oval (Fig. 1 G) and smaller (6.0 – 6.9 mm). The elytral apices of males of D. australis have weak epipleural spines, whereas in the males of D. unidentatus these are longer and more developed (Fig. 6 A). In dorsal view, the aedeagus of D. australis is distinct from that of D. unidentatus, as the median lobe is very narrow and without a constricted apex (Fig. 5 C), in comparison to the broader, more parallel-sided median lobe of D. unidentatus, which is abruptly constricted at its apex (Fig. 6 B). The females of D. australis can be distinguished from those of D. unidentatus by the elytral apices lacking epipleural spines, which are presented in D. unidentatus. The reproductive tract of D. australis has broader gonocoxae with the apex nearly straight, whereas in D. unidentatus the gonocoxae are more elongate, with the apex obliquely truncate and the lateral angle acuminate.	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8FFFD877CAFF3FFECDF8BE.taxon	distribution	Distribution. This species is widely distributed in the Oriental and Australian Regions. It has been recorded from China, Taiwan (Mazzoldi 1995); the Philippines (Ochs 1924; Freitag et al. 2016); Japan (Takizawa 1931); Indonesia (Ochs 1949, 1953): Java, Bali, Lombok, Sumba, Sulawesi, Buru; New Guinea (Ochs 1955), Australia (Ochs 1949; Watts & Hamon 2010); New Caledonia (Satô 1966; Mazzoldi 2010); and the Pacific Islands: Vanuatu (Watts & Hamon 2010) and Fiji (Ochs 1949). This is the first time it has been recorded in Thailand. Habitat. In Australia, D. australis has been found in reservoirs, swamps, and pools in rivers and streams (Watts & Hamon 2010). In the present study, BS collected D. australis on the water surface of ponds in the forest (Fig. 7 C) where it occurred among aquatic plants in shallow water. Additionally, it was found in shallow, stagnant streams.	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8FFFD877CAFF3FFECDF8BE.taxon	discussion	Discussion. Within Thailand, it was found in the northern, northeastern, western, and southern regions (Fig. 8 A) and was collected at low elevations ranging from 17 – 472 m a. s. l. It co-occurred with D. unidentatus and D. spinosus in ponds.	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8EFFD777CAF91DFE2FFCF6.taxon	description	(Figs. 1 E, 1 I, 4 B, 5 F – I, 7 D, 8 A)	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8EFFD777CAF91DFE2FFCF6.taxon	materials_examined	Material examined. THAILAND: Kanchanaburi Province: Thong Pha Phum Natl. Park, Huay Ka Yeang Stream, Hin Dat Subdistrict, Thong Pha Phum District, 14 ° 33 ' 18.0 '' N 98 ° 35 ' 51.8 '' E, 270 m a. s. l., 25. II. 2002, leg. S. Saeheag, 1 male (NHMW). Phitsanulok Province: Phu Hin Rongkla Natl. Park, Huai Khamin Noi Waterfall, Pool, 16 ° 59 ' N 101 ° 00 ' E, 1220 m a. s. l., 10. III. 2002, leg. R. Sites, A. Vitheepradit & K. Kirawanich, 1 female (UMC); same locality except for, 22. V. 2002, leg. CMU Team, 1 female (UMC); same locality except for, Waterwheel Falls, 16 ° 59 ' N 101 ° 00 ' E, 1280 m a. s. l., 12. VII. 2003, leg. N. Changthong, 1 female (THNHM); same locality except for, 15. XI. 2002, leg. CMU Team, 3 males (UMC, THNHM), 2 females (UMC); same locality except for, 5. V. 2003, leg. N. Changthong, 1 male (UMC); Thung Salaeng Luang Natl. Park, Tum Din Stream, Ban Mung Subdistrict, Noen Maprang District, 16 ° 29 ' 07.5 " N 100 ° 48 ' 31.2 " E, 894 m a. s. l., 23. III. 2011, leg. N. Sangpradub, 2 females (KKU).	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8EFFD777CAF91DFE2FFCF6.taxon	diagnosis	Diagnosis. Male (Fig. 1 E): Size: 15.0 – 17.0 mm. Body form broadly oval; apex of flagellomere VI darkly colored, black; elytral apices without parasutural spines, epipleural spines and serrations absent (Fig. 5 F), elytral apex rounded (Fig. 1 E); lateral margin of pronotum and elytron darkly colored, black; protrochanter apically without setae on ventral surface (Fig. 4 B); profemur with sub-apicoventral tooth; protibia club-shaped; venter reddish to brown (Fig. 1 I); epipleura reddish to black (Fig. 1 I); aedeagus (Figs. 5 G – H) with median lobe shorter than parameres, parallel-sided for 3 / 4 length, narrowed in apical 1 / 5, apex triangular, curved dorsally in lateral view. Female: Similar to male except for size: 13.4 – 15.7 mm; apex of flagellomere VI lightly colored, orange; profemur without sub-apicoventral tooth; gonocoxae elongate, lateral margins slightly rounded and expanded, apex rounded (Fig. 5 I). Differential diagnosis. Dineutus sitesi can be distinguished from all other congeners in Thailand by the broadly oval body form, large size, rounded elytral apex lacking spines and serrations, and males with a sub-apicoventral profemoral tooth.	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8EFFD777CAF91DFE2FFCF6.taxon	distribution	Distribution. This species is known only from Thailand where it was described from Phu Hin Rongkla National Park, Phitsanulok Province (Gustafson et al. 2016). Habitat. This species occurs in streams and pools beneath waterfalls (Fig. 7 D) (Gustafson et al. 2016).	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF8EFFD777CAF91DFE2FFCF6.taxon	discussion	Discussion. In this study, D. sitesi was found at the same localities in Phu Hin Rongkla National Park as previously reported by Gustafson et al. (2016). Additionally, we found this species in another stream within the same mountain range (Phetchabun Mountains) at Thung Salaeng Luang National Park, Phitsanulok Province at an elevation of 894 m a. s. l. D. sitesi was also collected from a stream in the Tenasserim Hills at Thong Pha Phum National Park, Kanchanaburi Province at an elevation of 270 m a. s. l. (Fig. 8 A). Thus, more collecting in the northern and western regions where the mountain ranges approach continuity will be required further in order to better understand its distribution.	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF80FFD577CAFC60FE77FD3E.taxon	description	(Figs. 1 F, 1 J, 4 C, 5 J – M, 7 C, 7 E, 8 A)	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF80FFD577CAFC60FE77FD3E.taxon	materials_examined	Material examined. THAILAND: Amnat Charoen Province: Kork Stream, Kham Khuean Kaeo Subdistrict, Chanuman District, 16 ° 12 ' 29.9 " N 104 ° 52 ' 11.6 " E, 188 m a. s. l., 23. XII. 2017, leg. B. Suksai, 2 males, 4 females (THNHM). Kalasin Province: Phu Pan Natl. Park, water supply pond at Park HQ, 16 ° 47 ' 38.8 " N 103 ° 50 ' 37.8 " E, 7. VI. 1998, leg. K. B. Simpson & A. Vitheepradit, L- 165, 1 male (UMC). Mukdahan Province: Huai Lao Waterfall, Ban Kho Subdistrict, Khamcha-I District, 16 ° 44 ' 36.9 " N 104 ° 21 ' 04.7 " E, 226 m a. s. l., 22. XII. 2017, leg. B. Suksai, 1 female (THNHM); Tadton Waterfall, Non Yang Subdistrict, Nong Sung District, 16 ° 29 ' 40.2 " N 104 ° 18 ' 47.6 " E, 208 m a. s. l., 22. XII. 2017, leg. B. Suksai, 1 female (THNHM). Nakhon Ratchasima Province: Sakaerat Environmental Research Station, Bon weir, U-dom Sap Subdistrict, Wang Nam Khiao District, 14 ° 29 ' 49.2 " N 101 ° 54 ' 55.5 " E, 472 m a. s. l., 27. III. 2018, leg. P. Chanteenok, 1 male (THNHM); same locality except for, 29. III. 2018, leg. P. Chanteenok, 1 male, 1 female (THNHM); Thap Lan Natl. Park, Khok Krachai Subdistrict, Khon Buri District, 14 ° 20 ' 13.6 '' N 102 ° 14 ' 48.0 '' E, 224 m a. s. l., 27. IV. 2014, leg. K. Piraonapicha, 7 males, 8 females (KKU, THNHM); same locality except for, Wang Tao Waterfall, Khok Krachai Subdistrict, Khon Buri District, 14 ° 19 ' 52.0 '' N 102 ° 14 ' 05.0 '' E, 224 m a. s. l., 23. III. 2013, leg. K. Piraonapicha, 2 males, 4 females (KKU). Nakhon Si Thammarat Province: Chulabhorn District, 56 km N of Phatthalung, 8 ° 03 ' N 99 ° 53 ' E, 21 m a. s. l., 31. V. 2003, leg. A. Vitheepradit & M. L. Ferro, L- 583, 7 males, 6 females (UMC). Sisaket Province: Huay Sala Wildlife Sanctuary, Sum Sai Waterfall, 14 ° 31.894 ' N 104 ° 20.419 ' E, 202 m a. s. l., 12. IV. 2004, leg. R. W. Sites & A. Vitheepradit, L- 622, 5 males, 3 females (UMC). Songkhla Province: Prince of Songkla University, 2. V. 1993, leg. Apinya, 1 female (UMC). Surat Thani Province: Ban Tha Rau Tai, Ban Na Doem District, 8 ° 56.567 ' N 99 ° 15.130 ' E, 4 m a. s. l., 20. VI. 2004, leg. A. Vitheepradit & T. Prommi, L- 782, 1 female (UMC). Ubon Ratchathani Province: Huay Sae Stream, Na Pho Klang Subdistrict, Khong Chiam District, 15 ° 32 ' 05.2 " N 105 ° 31 ' 06.7 " E, 131 m a. s. l., 23. XII. 2017, leg. B. Suksai, 3 males, 2 females (THNHM).	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF80FFD577CAFC60FE77FD3E.taxon	diagnosis	Diagnosis. Male (Fig. 1 F): Size: 6.4 – 8.0 mm. Body form oval; apex of flagellomere VI lightly colored; elytral apices weakly serrate, with parasutural and epipleural spines (Fig. 5 J); lateral margin of pronotum and elytron orange or yellow (Fig. 1 F); protrochanter apically with single series of few setae on ventral surface (Fig. 4 C); profemur without sub-apicoventral tooth; protibia wedge-shaped; venter yellow to brown (Fig. 1 J), epipleura yellow (Fig. 1 J); aedeagus (Figs. 5 K – L) with median lobe shorter than parameres, parallel-sided for 2 / 3 length, slightly narrowed in apical half, acuminate in apical fifth, with tip narrowly rounded, weakly straight in lateral view. Female: Similar to male except for size: 6.9 – 8.1 mm; gonocoxae elongate, lateral margin rounded, apex weakly rounded (Fig. 5 M). Differential diagnosis. Dineutus spinosus can be distinguished from congeners in Thailand by the lightly colored margin of the pronotum and elytron and by the spinose elytral apex having both parasutural and epipleural spines developed (Table 1). No other species of Dineutus in Thailand has this combination of characters. Porrorhynchus marginatus has these features as well, but is much larger in size and can be distinguished by the elongate, triangular labrum in addition to other features of the forelegs.	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF80FFD577CAFC60FE77FD3E.taxon	distribution	Distribution. This is a widespread species found in the eastern portion of the Indian subcontinent and throughout Southeast Asia from Sri Lanka and eastern India through Assam, Bangladesh, Myanmar, Thailand, Laos, as far east as Vietnam (Ochs 1929, 1930; Mouchamps 1949; Brinck 1981; Vazirani 1984), and as far south as Singapore (Hendrich et al. 2004), Sumatra (Ochs 1929), and Borneo (Ochs 1928). Habitat. It occurs on exposed rivers, streams, ponds, and water tanks (Figs. 7 C, E). (Brinck 1981).	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF80FFD577CAFC60FE77FD3E.taxon	discussion	Discussion. Dineutus spinosus is currently known from only the northeastern and southern regions of Thailand (Fig. 8 A) where it occurs at low to medium elevations (4 – 472 m a. s. l.). It has not been found at high elevation. We suspect that it might occur in other localities in Thailand with the same habitats at similar elevations. Both D. spinosus and the similar congener D. orientalis, which has a primarily more eastern and northern distribution, are known to co-occur in Laos and Vietnam (Mouchamps 1949; Brinck 1981). The latter species has yet to be encountered in Thailand and was not found during our surveys, despite extensive sampling in northeastern Thailand near the Laotian border (Fig. 8 A).	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF82FFD277CAFCA3FE23F847.taxon	description	(Figs. 1 G, 4 D, 6 A – D, 7 C, 7 F – G, 8 A)	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF82FFD277CAFCA3FE23F847.taxon	materials_examined	Material examined. THAILAND: Amnat Charoen Province: Kork Stream, Kham Khuean Kaeo Subdistrict, Chanuman District, 16 ° 12 ' 29.9 " N 104 ° 52 ' 11.6 " E, 188 m a. s. l., 23. XII. 2017, leg. B. Suksai, 2 males, 2 females (THNHM). Khon Kaen Province: Khon Kaen University, wastewater treatment pond 8, Nai Mueang Subdistrict, Mueang Khon Kaen District, 16 ° 27 ' 48.2 " N 102 ° 48 ' 29.3 " E, 169 m a. s. l., 21. XI. 2001, leg. B. Suksai, 1 male, 1 female (KKU); Phong River, Ban Huai Sai Nang, Si Chomphu Subdistrict, Si Chomphu District, 16 ° 52 ' 06.5 " N 102 ° 10 ' 58.2 " E, 210 m a. s. l., 11. II. 1995, leg. N. Sangpradub, 6 males, 8 females (KKU); Pond at Ban Kho, Ban Kho Subdistrict, Mueang Khon Kaen District, 16 ° 34 ' 13.9 " N 102 ° 46 ' 53.8 " E, 180 m a. s. l., 26. XI. 2016, leg. B. Suksai, 48 males, 65 females (KKU, THNHM). Krabi Province: Pond at Ban Paga Sai, Nuea Khlong Subdistrict, Nuea Khlong District, 8 ° 02 ' N 99 ° 01 ' E, 27 m a. s. l., 3. VI. 2005, leg. R. W. Sites, A. Vitheepradit & T. Prommi, L- 828, 1 male (UMC). Mukdahan Province: Huai Lao Waterfall, Ban Kho Subdistrict, Khamcha-I District, 16 ° 44 ' 36.9 " N 104 ° 21 ' 04.7 " E, 226 m a. s. l., 22. XII. 2017, leg. B. Suksai, 1 male, 1 female (THNHM); Tadton Waterfall, Non Yang Subdistrict, Nong Sung District, 16 ° 29 ' 40.2 " N 104 ° 18 ' 47.6 " E, 208 m a. s. l., 22. XII. 2017, leg. B. Suksai, 1 male, 2 females (THNHM). Nakhon Ratchasima Province: Sakaerat Environmental Research Station, Boa yaepun, U-dom Sap Subdistrict, Wang Nam Khiao District, 14 ° 27 ' 56.9 " N 101 ° 54 ' 11.7 " E, 392 m a. s. l., 26. X. 2013, leg. B. Suksai, 1 male (KKU); same locality except for, Bon weir, U-dom Sap Subdistrict, Wang Nam Khiao District, 14 ° 29 ' 49.2 " N 101 ° 54 ' 55.5 " E, 472 m a. s. l., 27. III. 2018, leg. P. Chanteenok, 5 males, 6 females (THNHM); same locality except for, 29. III. 2018, leg. P. Chanteenok, 4 males, 6 females (THNHM); same locality except for, 8. IV. 2018, leg. B. Suksai, O. Pornsophon, T. Jantaranakee & S. Phengsalung, 1 male (KKU). Phetchabun Province: Nam Churn Stream, Kok Mon Subdistrict, Nam Nao District, 16 ° 40 ' 27.0 " N 101 ° 44 ' 03.0 " E, 278 m a. s. l., 21. III. 2017, leg. B. Suksai, 2 males, 3 females (THNHM). Trang Province: Sikao District, ca. 8 km N of Chao Mai Natl. Park, 7 ° 28 ' 09.3 " N 99 ° 20 ' 09.5 " E, 5 m a. s. l., 9. I. 2006, leg. A. Vitheepradit & T. Prommi, mangrove, L- 906, 1 female (UMC).	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF82FFD277CAFCA3FE23F847.taxon	diagnosis	Diagnosis. Male (Fig. 1 G): Size: 6.0 – 6.7 mm. Body form narrowly oval; apex of flagellomere VI darkly colored; elytral apices truncate and straight without parasutural spines, with epipleural spines and serrations (Figs. 1 G, 6 A); lateral marginal of pronotum and elytron black; protrochanter apically with single series of few setae on ventral surface (Fig. 4 D); profemur without sub-apicoventral tooth; protibia wedge-shaped; venter, brown to black; epipleura brown; aedeagus (Figs. 6 B – C) with median lobe slightly longer than parameres, parallel-sided after basal fourth, strongly acuminate in apical 1 / 6, apex with tip rounded, straight in lateral view. Female: Similar to male except for size: 6.4 – 6.9 mm; gonocoxae elongate, lateral margin rounded, apex obliquely truncate with apicolateral corner produced (Fig. 6 D). Differential diagnosis. Dineutus unidentatus is closest to D. australis, which also occurs in Thailand. See the differential diagnosis under D. australis to distinguish between the two species.	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF82FFD277CAFCA3FE23F847.taxon	distribution	Distribution. Widely distributed in the Indian subcontinent and Southeast Asia from western India and Sri Lanka through Assam, Bangladesh, Myanmar, Thailand, Cambodia, Laos, to Vietnam and Hainan Island (Ochs 1929, 1930; Mouchamps 1949; Brinck 1981; Vazirani 1984; Mazzoldi 1995) as far south as the Malay peninsula (Balke et al. 2004) and Perak Island (Ochs 1929). The species has not been recorded from Singapore (Hendrich et al. 2004) and historical records from Java are considered erroneous (Brinck 1981). Habitat. In Sri Lanka, the species has been found in rivers, streams, ponds, water tanks, paddy fields, and a slightly brackish lagoon (Brinck 1981). On Perak Island, Malaysia, the species was taken near a waterfall in a stream (Ochs 1929). We found this species near the margins of a stagnant stream and in ponds where it formed rafts of many individuals (Figs. 7 C, F – G).	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF82FFD277CAFCA3FE23F847.taxon	discussion	Discussion. We found D. unidentatus only in the northeastern and southern regions of Thailand (Fig. 8 A). It was found at low to medium elevation (5 – 472 m a. s. l.) and co-occurred in ponds and streams with D. spinosus. It has not been found at high elevation. We suspect that it might be found in other localities in Thailand with the same habitat and elevation.	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF87FFCF77CAFAE5FD08FCD9.taxon	description	(Figs. 1 H, 4 E – F, 6 E – G, 7 H, 8 B)	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF87FFCF77CAFAE5FD08FCD9.taxon	materials_examined	Material examined. THAILAND: Amnat Charoen Province: Tat Yai Waterfall, Khok Kong Subdistrict, Chanuman District, 16 ° 04 ' 12.0 " N 104 ° 57 ' 01.9 " E, 160 m a. s. l., 23. XII. 2017, leg. B. Suksai, 1 male, 1 female (THNHM). Chaiyaphum Province: Huay Tad Fa Noi, Khon San district, 16 ° 27 ' 14.8 " N 101 ° 41 ' 19.8 " E, 7. II. 1996, leg. N. Sangpradub, 1 male (KKU); Nam Nao Natl. Park, Phromlaeng Stream, Thung Phra Subdistrict, Khon San District, 16 ° 38 ' 22.8 " N 101 ° 34 ' 55.6 " E, 800 m a. s. l., 15. XII. 2013, leg. N. Sangpradub & R. Somnak, 2 females (THNHM); 11. V. 2014, leg. N. Sangpradub & R. Somnak, 1 female (KKU); same locality except for, 19. VII. 2014, leg. N. Sangpradub & R. Somnak, 1 female (KKU); same locality except for, 16 ° 38 ' 19.5 " N 101 ° 34 ' 57.2 " E, 790 m a. s. l., 19. VII. 2014, leg. N. Sangpradub & R. Somnak, 1 male (THNHM); same locality except for, 16 ° 38 ' 20.8 " N 101 ° 34 ' 55.8 " E, 794 m a. s. l., 15. XII. 2013, leg. N. Sangpradub & R. Somnak, 1 female (THNHM); same locality except for, 19. VII. 2014, leg. N. Sangpradub & R. Somnak, 1 male (THNHM); Phu Khieo Wildlife Sanctuary, " Nam Prom ", 16 ° 19 ' 59.9 " N 101 ° 36 ' 59.8 " E, 4. IV. 1994, leg. W. Shephard, WDS A 1053, 7 spec. (NHMW); Phulong Stream, Tadrinthong Village, Sa Phon Thong Subdistrict, Kaset Sombun District, 16 ° 12 ' 08.1 '' N 102 ° 06 ' 01.8 '' E, 500 m a. s. l., 30. VIII. 2003, leg. C. Srichan, 1 male, 2 females (KKU). Chanthaburi Province: 15 km E Chanthaburi City, stream at Philiu Waterfall, 12 ° 36 ' 09.4 " N 102 ° 14 ' 46.3 " E, 29. I. 1995, leg. P. P. Chen, 1 spec. (NHMW); Khao Soi Dao Wildlife Sanctuary, stream from Khao Soi Dao Waterfall, 13 ° 05 ' 48.6 " N 102 ° 10 ' 19.9 " E, 523 m a. s. l., 17. I. 2016, leg. R. W. Sites, L- 1911, 1 male, 1 female (UMC); stream of Phlio Waterfall, Khom Bang Subdistrict, Mueang Chanthaburi District, 12 ° 31 ' 29.2 " N 102 ° 10 ' 25.5 " E, 115 m a. s. l., 30. V. 2017, leg. B. Suksai & C. Yatfung, 1 male, 1 female (THNHM). Chiang Mai Province: " Soppong-Pai ", 19 ° 00 ' 28.1 " N 98 ° 43 ' 39.4 " E, 1800 m a. s. l., 1 – 8. V. 1993, leg. P. Pacholatko & L. Dembicky, 1 spec. (NHMW). Chumphon Province: Khun Mae Yai Moun Wildlife Sanctuary, Haew Lome Waterfall, water surface, 9 ° 43 ' N 98 ° 40 ' E, 120 m a. s. l., 22. V. 2005, leg. R. W. Sites, A. Vitheepradit & T. Prommi, L- 785 b, 1 male, 1 female (UMC). Kanchanaburi Province: 30 km N Thong Pha Phum, 14 ° 58 ' 11 " N 98 ° 38 ' 35 " E, 160 m a. s. l., 13. XII. 2010, leg. H. Freitag, 22 b, 1 spec. (NHMW); Thong Pha Phum Reforestation Station, Mae Nam Noi, Sai Yok District 14 ° 31 ' N 98 ° 37 ' E, 204 m a. s. l., 12. IV. 2002, leg. UMC & CMU teams, L- 335, 4 males, 8 females (UMC); Heuy Kob, Sangkhla Buri District, 15 ° 13 ' N 98 ° 22 ' E, 289 m a. s. l., 13. IV. 2002, leg. UMC & CMU teams, gravel stream, 1 male, 10 females (UMC); same locality except for, gravel stream, L- 339, 1 spec. (UMC); Heuy Ka Yaeng, at Ban Pracham Mai, 19. I. 2015, leg. R. W. Sites, gravel riffles, L- 1871, 1 female (UMC); Heuy Ou Long, opposite Keong Ka Wia Reforestration Station, 14 ° 33.199 ' N 98 ° 34.238 ' E, 326 m a. s. l., 19. I. 2015, leg. R. W. Sites & A. Vitheepradit, gravel and vegetated margins, L- 1872, 1 male, 4 females (UMC). Loei Province: Dan Sai, " Lomie Mt. ", 17 ° 16 ' 47.4 " N 101 ° 09 ' 01.5 " E, 1. III. 1955, leg. R. E. Elbel, ZML. 2010 / 356, 1 spec. (MZLU); Loei River, Ban Non Phatthana, Loei Wang Sai Subdistrict, Phu Luang District, 17 ° 06 ' 24.1 " N 101 ° 28 ' 43.1 " E, 20. V. 2017, leg. P. Sapewisut, C. Jaitamart & T. Paotajai, 1 male, 2 females (THNHM); same locality except for, Ban Wang Yao, Wang Yao Subdistrict, Dan Sai District, 17 ° 07 ' 40.5 " N 101 ° 28 ' 14.5 " E, 20. V. 2017, leg. P. Sapewisut, C. Jaitamart & T. Paotajai, 2 males, 2 females (THNHM); Na Haeo, River bank, 17 ° 28 ' 40.4 " N 100 ° 58 ' 56.4 " E, 15. V. 2003, leg. P. Grootaert, J. Constant & K. Smets, Light trap, 3 spec. (IRSB); Phu Luang Wildlife Sanctuary, 17 ° 13 ' 51.2 " N 101 ° 30 ' 06.5 " E, 700 – 900 m a. s. l., 8 – 14. X. 1984, leg. Karsholt, Lomholdt & Nielsen, 8 spec. (NHMD); Phu Rua Natl. Park, Huay Pai Waterfall, 17 ° 28 ' 52.7 " N 101 ° 21 ' 06.5 " E, 10. VI. 1998, leg. R. W. Sites, K. B. Simpson & A. Vitheepradit, L- 175, 1 spec. (UMC). Mae Hong Son Province: " Ban Si Lang ", 19 ° 19 ' N 97 ° 59 ' E, 1200 m a. s. l., 23 – 31. V. 1991, leg. L. Dembicky, 1 spec. (NHMW); Huai Sua Tao, 19 ° 15 ' 34.9 " N 97 ° 54 ' 12.6 " E, V. 1992, leg. L. Dembicky, 1 spec. (NHMW); Huay Pha, stream <1 km N of Ban Huay Pha, 19 ° 25 ' 50.8 " N 97 ° 59 ' 49.6 " E, 360 m a. s. l., 19. IV. 2009, leg. R. W. Sites, A. Vitheepradit & T. Prommi, L- 1049, 1 male (UMC). Mukdahan Province: Phu Pa Yon Natl. Park, Keang Pho Waterfall, 16 ° 45.368 ' N 104 ° 14.736 ' E, 314 m a. s. l., 23. IV. 2004, leg. A. Vitheepradit, margin, L- 634, 3 males, 5 females (UMC). Nakhon Nayok Province: Khao Yai Natl. Park, ca. 700 m, 29. IX – 6. X. 1984, leg. Karsholt, Lomholdt & Nielsen, 6 spec. (NHMD); same locality except for, 200 m E of Heaw Narok Waterfall, 14 ° 17 ' N 101 ° 23 ' E, 397 m a. s. l., 5. IV. 2004, leg. R. W. Sites & A. Vitheepradit, L- 602, 1 male, 1 female (UMC). Nakhon Ratchasima Province: Khao Yai Natl. Park, Heaw Su Wat Waterfall, 14 ° 25.963 ' N 101 ° 24.948 ' E, 380 m a. s. l., 6. IV. 2004, leg. R. W. Sites & A. Vitheepradit, L- 605, 3 females (UMC); same locality except for, 700 – 800 m, 31. IV. 1990, leg. E. Fuller, 3 spec. (NHMW); pooled margins of slow stream behind the Youth Camp buildings, 4. I. 2011, leg. R. W. Sites, L- 1268, 4 males, 1 female (UMC); Lam Takong Stream, Musi Subdistrict, Pak Chong District, 14 ° 30 ' 41.6 " N 101 ° 22 ' 49.6 " E, 378 m a. s. l., 9. IV. 2018, leg. B. Suksai, O. Pornsophon, T. Jantaranakee & S. Phengsalung, 2 females (THNHM); Thap Lan Natl. Park, Khok Krachai Subdistrict, Khon Buri District, 14 ° 19 ' 52.0 '' N 102 ° 14 ' 05.0 '' E, 224 m a. s. l., 24. XI. 2013, leg. K. Piraonapicha, 1 male, 1 female (KKU); same locality except for, 27. IV. 2014, leg. K. Piraonapicha, 2 males, 4 females (KKU); same locality except for, 14 ° 20 ' 13.6 '' N 102 ° 14 ' 48.0 '' E, 224 m a. s. l., 27. IV. 2014, leg. K. Piraonapicha, 2 males, 3 females (KKU); same locality except for, 5. III. 2017, leg. K. Piraonapicha, 1 male, 1 female (KKU). Nan Province: Ban Pha Khap, 19 ° 07 ' 28.2 " N 101 ° 08 ' 54.2 " E, 15 – 20. V. 1992, leg. P. Pecholatko, 2 spec. (NHMW); Mae Charim Natl. Park, Nam Wa River, 18 ° 36 ' N 100 ° 59 ' E, 335 m a. s. l., 13. III. 2002, leg. CMU Team, 2 spec. (UMC); Tat Man Waterfall, 19 ° 17.187 ' N 100 ° 47.312 ' E, 352 m a. s. l., 17. IV. 2009, leg. R. W. Sites, A. Vitheepradit & T. Prommi, stream with waterfall, L- 1045, 2 females (UMC); Yao River, Du Pong Subdistrict, Santi Suk District, 18 ° 56 ' 44.3 " N 100 ° 48 ' 37.7 " E, 251 m a. s. l., 13. V. 2017, leg. B. Suksai, S. Kullasoot & C. Yatfung, 3 males, 5 females (THNHM). Phetchabun Province: Nam Nao Natl. Park, stream front of Tum Yai Nam Nao, Lak Dan Subdistrict, Nam Nao District, 16 ° 56 ' 48.2 " N 101 ° 30 ' 24.5 " E, 27. III. 1998, leg. N. Sangpradub, 2 males, 1 females (KKU); same locality except for, Yakruae Stream, Nam Nao Subdistrict, Nam Nao District, 16 ° 44 ' 19.7 " N 101 ° 34 ' 26.4 " E, 840 m a. s. l., 17. VIII. 2014, leg. N. Sangpradub & R. Somnak, 1 female (THNHM); same locality except for, 21. IX. 2014, leg. N. Sangpradub & R. Somnak, 1 female (THNHM); same locality except for, 13. XII. 2014, leg. N. Sangpradub & R. Somnak, 1 male (THNHM); same locality except for, 16 ° 44 ' 19.7 " N 101 ° 34 ' 36.2 " E, 827 m a. s. l., 16. XII. 2013, leg. N. Sangpradub & R. Somnak, 1 female (THNHM); same locality except for, 15. VI. 2014, leg. N. Sangpradub & R. Somnak, 1 female (THNHM); same locality except for, 18. X. 2014, leg. N. Sangpradub & R. Somnak, 1 male, 1 female (THNHM); same locality except for, 16 ° 44 ' 27.9 " N 101 ° 34 ' 46.5 " E, 807 m a. s. l., 18. I. 2014, leg. N. Sangpradub & R. Somnak, 1 female (THNHM); same locality except for, 5 km E Sila, " Mae Nam Pa Sak ", 17 ° 04 ' 20.3 " N 101 ° 22 ' 31.1 " E, 2. III. 1994, leg. W. Shephard, WDS A 1025, 1 spec. (NHMW); Khao Kor Non-Hunting Area, Sridit Waterfall, 16 ° 37 ' N 100 ° 56 ' E, 702 m a. s. l., 11. V. 2004, leg. A. Vitheepradit & T. Prommi, L- 677, 1 spec. (UMC). Phang Nga Province: Bang Won Subdistrict, Khura Buri District, 8 ° 59 ' N 98 ° 26 ' E, 45 m a. s. l., 27. IV. 2002, leg. A. Vitheepradit & K. Kirawanich, gravel stream, L- 375, 13 males, 9 females (UMC); Khao Lak Stream, 8 ° 37 ' 08.4 " N 98 ° 14 ' 51.5 " E, 10. I. 2003, leg. H. Forster, 6 spec. (NHMW); Si Phang Nga Waterfall, Ban Tamnang, Khura Buri District, Si Phang Nga Natl. Park, 29. XI. 2006, leg. H. Zettel, 48, 4 spec. (NHMW); Tam Nang Stream, Bang Wan Subdistrict, Khura Buri District, 8 ° 59 ' 50.3 " N 98 ° 26 ' 55.4 " E, 110 m a. s. l., 24. V. 2017, leg. B. Suksai & C. Yatfung, 1 female (THNHM); Trem stream, Khura Subdistrict, Khura Buri District, 9 ° 19 ' 54.5 " N 98 ° 25 ' 02.8 " E, 110 m a. s. l., 24. V. 2017, leg. B. Suksai & C. Yatfung, 2 males, 2 females (THNHM). Phatthalung Province: Lam Sin Stream, Kong Ra Subdistrict, Kong Ra District, 7 ° 30 ' 39.8 " N 99 ° 56 ' 06.3 " E, 150 m a. s. l., 23. V. 2017, leg. B. Suksai & C. Yatfung, 2 males, 3 females (THNHM). Prachin Buri Province: Khao Yai Natl. Park, 14 ° 20 ' N 101 ° 30 ' E, 1000 m a. s. l., 26. III. 1992, leg. E. Hüttinger, 10 spec. (NHMW); same locality except for, Kaeng Wang Thong, 14 ° 10.077 ' N 101 ° 43.420 ' E, 8. IV. 2004, leg. R. W. Sites & A. Vitheepradit, L- 608, 8 males, 10 females (UMC). Rayong Province: Khao Chamao-Khao Natl. Park (" Khao Chamao Natl. Park "), 12 ° 57 ' 54.0 " N 101 ° 43 ' 55.2 " E, 12. XII. 1990, leg. M. A. Jäch, Sites codes 14, 1 spec. (NHMW). Sakon Nakhon Province: " 11 km NE Kham Poem ", " Huai Ya ", 16 ° 56 ' 35.5 " N 104 ° 02 ' 31.2 " E, 5. III. 1994, leg. W. Shephard, WDS A 1027, 4 spec. (NHMW); " Keek poo ", 9. XI. 1954, leg. R. E. Elbel, Bar codes and specimen numbers ZML. 2010 / 357, 1 spec. (MZLU); Phu Phan Natl. Park, Huay Wian Prai, Phu Phan District, 16 ° 57 ' 49.9 " N 103 ° 46 ' 38.9 " E, 23. V. 1998, leg. N. Sangpradub, 1 male (KKU). Saraburi Province: Khao Yai Natl. Park., Lam Takong Stream, 2. I. 2008, leg. R. W. Sites, L- 1025, 3 males, 6 females (UMC). Satun Province: Ma Lao Stream, Wang Prachan Subdistrict, Khuan Don District, 6 ° 47 ' 44.5 " N 100 ° 08 ' 41.9 " E, 159 m a. s. l., 25. V. 2017, leg. B. Suksai & C. Yatfung, 1 male, 2 females (THNHM). Songkhla Province: Khao Nam Chang Natl. Park, SW Nathawee, 13. I. 1995, leg. R. W. Sites & B. Nichols, 1 male, 4 females (UMC); same locality except for, 102 km SE Hat Yai District, Na Thawi District, 6 ° 36 ' N 100 ° 36 ' E, 100 m a. s. l., 15. VI. 2001, leg. R. W. Sites, L- 246, 1 male, 4 females (UMC); Khoa Nam Khang (" Khao Nam Chang "), SW Na Thawi (" SW Nathawee "), 13. I. 1995, leg. R. W. Sites & B. Nichols, 5 spec. (UMC); Ton Nga Chang Natl. Park, stream at Buddhist temple, 30. I. 1995, leg. B. J. Nichols, L- 81, 1 male, 2 females (UMC); same locality except for, 6. VI. 2001, leg. R. W. Sites, L- 127, 9 males, 15 females (UMC); 9. VI. 2001, leg. R. W. Sites, L- 236, 23 males, 31 females (UMC). Sa Kaeo Province: Pang Sida Natl. Park, Khlong Huay Nam Yen, 14 ° 02.399 ' N 102 ° 15.955 ' E, 218 m a. s. l., 16. IV. 2004, leg. R. W. Sites & A. Vitheepradit, L- 630, 3 males, 12 females (UMC); same locality except for, Pang Sida Waterfall, 13 ° 59.634 ' N 102 ° 12.408 ' E, 209 m a. s. l., 15. IV. 2004, leg. R. W. Sites & A. Vitheepradit, L- 627, 3 males, 2 females (UMC). Suphan Buri Province: Bang Pla Ma District, Tumbon Salee, Moo Sarm, 14 ° 18 ' N 100 ° 14 ' E, 11 m a. s. l., 4. VII. 2004, leg. A. Vitheepradit, L- 784, 2 females (UMC). Surat Thani Province: Ban Chong Lom; Khlong Sok, Phanom District, 8 ° 52 ' N 98 ° 40 ' E, 43 m a. s. l., 23. V. 2003, leg. M. L. Ferro & A. Vitheepradit, L- 563, 3 males, 7 females (UMC); Khao Sok Natl. Park, 8 ° 53 ' 45.2 " N 98 ° 38 ' 34.0 " E, 15. I. 2003, leg. H. Forster, 5 spec. (NHMW); same locality except for, 5 – 9. VI. 1999, leg. D. Šanc, Jiří Hájek Collection, 5 spec. (NMPC). Ubon Ratchathani Province: Huay Luang Stream, Na Chaluai Subdistrict, Na Chaluai District, 14 ° 26 ' 55.7 " N 105 ° 12 ' 34.4 " E, 173 m a. s. l., 24. XII. 2017, leg. B. Suksai, 2 males, 1 female (THNHM); Huay Sae Stream, Na Pho Klang Subdistrict, Khong Chiam District, 15 ° 32 ' 05.2 " N 105 ° 31 ' 06.7 " E, 131 m a. s. l., 23. XII. 2017, leg. B. Suksai, 1 male (THNHM); Phu Chong Na Yoi Natl. Park, Huay Kan Din Dum Stream, Na Chaluai Subdistrict, Na Chaluai District, 14 ° 25 ' 40.3 " N 105 ° 16 ' 34.3 " E, 390 m a. s. l., 23. XI. 2012, leg. K. Rattanachan, 1 male (KKU); same locality except for, Huay Laung, 14 ° 26.513 ' N 105 ° 16.449 ' E, 172 m a. s. l., 11. IV. 2004, leg. R. W. Sites & A. Vitheepradit, L- 616, 5 males, 14 females (UMC); same locality except for, UV pan trap, 14 ° 26.125 ' N 105 ° 15.360 ' E, 231 m a. s. l., 11. IV. 2004, leg. R. W. Sites & A. Vitheepradit, L- 615, 1 male (UMC). Yala Province: Betong, " Gunung Cang dun vill. ", 5 ° 47 ' 09.4 " N 101 ° 02 ' 08.9 " E, 25. III – 22. IV. 1993, leg. J. Strnad, 1 spec. (NHMW).	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF87FFCF77CAFAE5FD08FCD9.taxon	diagnosis	Diagnosis. Male (Fig. 1 H): Size: 15.6 – 18.6 mm. Body form broadly oval; dorsally olive-green to bronzybrown; labrum long and triangular; elytral apices with parasutural and epipleural spines, sutural angle present; lateral margin of orbital ridge, pronotum and elytron yellow or white, with dark spot near basal third of length of lateral margin of elytron (Fig. 1 H), apicolaterally half of length of lateral margin of elytra with sawtooth-like spines reaching almost epipleural spine; protrochanter apically with small cluster setae at apex of ventral surface (Figs. 4 E – F); protibia club-shaped, apex with spines; venter and epipleura yellow; aedeagus (Figs. 6 E – F) with median lobe shorter than parameres, parallel-side in basal half, expanded in apical half, apex acuminate in apical 1 / 6 length of median lobe, apex with tip truncate (Fig. 6 E), curved dorsally in lateral view (Fig. 6 F). Female: Similar size to male: 15.4 – 17.4 mm; protrochanter apically without small cluster of setae at apex and without setae on ventral surface; gonocoxae short, lateral margin straight weakly angled toward apex, apex obliquely truncate (Fig. 6 G). Differential diagnosis. Porrorhynchus marginatus is the only Porrorhynchus found in Thailand. It can be easily recognized from the other Thai Gyrinidae by its large body size and long, triangular labrum for which it derives its common name in English, the snouted whirligig beetle. Porrorhynchus marginatus is also unique in having the lateral margin of the orbital ridge yellow or white in color.	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF87FFCF77CAFAE5FD08FCD9.taxon	distribution	Distribution. This species has been recorded as far northwest as Zayü Co. China (Jäch et al. 2012) and south and east through Myanmar, Thailand, Laos, Vietnam, Malaysia, and Indonesia far as Java and Borneo (Ochs 1927, 1930; Gustafson & Miller 2016). Habitat. It has been found in small, forested streams with elevations above 100 m a. s. l. and up to 1,000 m a. s. l. (Ochs 1927; Gustafson & Miller 2016). Ochs (1927) reported that P. marginatus was found in unpolluted localities and always near the water’s edge in the shallower parts of the streams. We found this species only in streams with shaded areas and slow current with substrates including pebble, gravel and sand (Fig. 7 H), at elevations ranging from 11 to 1,800 m a. s. l., but most often at 100 – 900 m a. s. l.	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
03DC697BFF87FFCF77CAFAE5FD08FCD9.taxon	discussion	Discussion. Porrorhynchus marginatus is a common, attractive species of Gyrinidae in Thailand, and as suggested by Ochs (1927), was the most common species encountered in several streams. Our survey revealed that P. marginatus occurs in all major regions of Thailand (Fig. 8 B). This study adds many additional Thai localities to those presented by Gustafson & Miller (2016).	en	Suksai, Benjamart, Gustafson, Grey T., Sites, Robert W., Sangpradub, Narumon (2021): The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071 (1): 97-117, DOI: https://doi.org/10.11646/zootaxa.5071.1.5
