The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini Author Suksai, Benjamart 0000-0002-2472-6100 benjamartbenjamart@gmail.com Author Gustafson, Grey T. Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas 66045, USA. & Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, 86011, USA. Author Sites, Robert W. 0000-0002-3895-813X Enns Entomology Museum, Division of Plant Science, University of Missouri-Columbia, Missouri 65211, USA. SitesR @ missouri. edu; https: // orcid. org / 0000 - 0002 - 3895 - 813 X Author Sangpradub, Narumon Applied Taxonomic Research Center, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand text Zootaxa 2021 2021-11-22 5071 1 97 117 journal article 3307 10.11646/zootaxa.5071.1.5 f5a054cf-41c7-40cd-bac9-63e1ea8d1b8e 1175-5326 5723327 C7DFE939-E932-4570-8496-7A67A51D4D7A Dineutus spinosus ( Fabricius, 1781 ) ( Figs. 1F, 1J , 4C , 5J–M , 7C, 7E , 8A ) 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 ) . Diagnosis. Male ( Fig. 1F ): 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. 5J ); lateral margin of pronotum and elytron orange or yellow ( Fig. 1F ); protrochanter apically with single series of few setae on ventral surface ( Fig. 4C ); profemur without sub-apicoventral tooth; protibia wedge-shaped; venter yellow to brown ( Fig. 1J ), epipleura yellow ( Fig. 1J ); aedeagus ( Figs. 5K–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. 5M ). TABLE 1. Morphological comparison of species of Dineutus and Porrorhynchus in Thailand.
Character D. australis D. sitesi D. spinosus D. unidentatus P . marginatus
Male
Body length (mm) 7.6–8.2 15.0–17.0 6.4–8.0 6.0–6.7 15.6–18.6
Body form oval broadly oval oval narrowly oval broadly oval
Apex of flagellomere VI darkly colored darkly colored lightly colored darkly colored darkly colored
Elytral apices with parasutural spines No No Yes No Yes
Epipleural spines present Yes No Yes Yes Yes
Elytral apices with serration Yes No weak serration Yes weak serration
Lateral marginal of pronotum and elytron darkly colored, black to brown darkly colored, black light colored, orange or yellow dark colored, black light colored, yellow or white
Ventral surface of protrochanter apically with patches of thick setae without setae and patches of thick setae with few setae with few setae with small cluster setae
Profemur with sub-apicoventral tooth No Yes No No No
Shape of protibial wedge-shaped club-shaped wedge-shaped wedge-shaped club-shaped
Venter colored black reddish to brown yellow to brown brown to black yellow
Epipleura colored brownish reddish to black yellow brown yellow
Female
Body length (mm) 8.1–8.2 13.4–15.7 6.9–8.1 6.4–6.9 15.4–17.4
Body form oval broadly oval oval narrowly oval broadly oval
Apex of flagellomere VI darkly colored lightly colored lightly colored darkly colored darkly colored
Elytral apices with parasutural spines No No Yes No Yes
Epipleural spines present No No Yes Yes Yes
Elytral apices with serration Yes No weak serration Yes weak serration
Ventral surface of protrochanter apically with setae without setae and patches of thick setae with setae with setae without setae and small cluster setae
Profemur with sub-apicoventral tooth No No No No No
Shape of protibial wedge shaped club-shaped wedge shaped wedge shaped club-shaped
Venter colored black reddish to brown yellow to brown brown to black yellow
Epipleura colored brownish reddish to black yellow black yellow
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. 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. 7C, E ). ( Brinck 1981 ). Discussion. Dineutus spinosus is currently known from only the northeastern and southern regions of Thailand ( Fig. 8A ) 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. 8A ).