Dineutus sitesi Gustafson, Hájek & Miller, 2016

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), pp. 97-117 : 104-106

Dineutus sitesi Gustafson, Hájek & Miller, 2016

( Figs. 1E, 1I , 4B , 5F–I , 7D , 8A )

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) .

Diagnosis. Male ( Fig. 1E ): 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. 5F ), elytral apex rounded ( Fig. 1E ); lateral margin of pronotum and elytron darkly colored, black; protrochanter apically without setae on ventral surface ( Fig. 4B ); profemur with sub-apicoventral tooth; protibia club-shaped; venter reddish to brown ( Fig. 1I ); epipleura reddish to black ( Fig. 1I ); aedeagus ( Figs. 5G–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. 5I ).

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.

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. 7D ) (Gustafson et al. 2016).

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. 8A ). 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.

Figures

FIGURE 1. Habitus of Gyrinini and Dineutini species: (A) Gyrinus sericeolimbatus, dorsal view, female; (B) G. smaragdinus, dorsal view, male; (C–D) Dineutus australis, dorsal view: (C) male; (D) female; (E) D. sitesi, dorsal view, male; (F) D. spinosus, dorsal view, male; (G) D. unidentatus, dorsal view, male; (H) Porrorhynchus marginatus, dorsal view, male; (I) D. sitesi, ventral view, male; (J) D. spinosus, ventral view, male. Scale bars = 3 mm.

FIGURE 4. SEM photographs of protochanters in species of Dineutus and Porrorhynchus (males): (A) D. australis, patch of thick setae (arrow), scale bar = 100 μm; (B) D. sitesi, protrochanter without setae (arrow), scale bar = 1 mm; (C) D. spinosus, setae (arrow), scale bar = 100 μm; (D) D. unidentatus, setae (arrow), scale bar = 100 μm; (E–F) P. marginatus, cluster setae (square and arrow): (E) scale bar = 500 μm; (F) scale bar = 100 μm.

FIGURE 5. Elytral apex, aedeagus and gonocoxae of species of Dineutus: (A–E) D. australis: (A–B) elytral apex, scale bar = 2 mm: (A) male; (B) female; (C–D) aedeagus, scale bar = 0.5 mm: (C) dorsal view; (D) lateral view; (E) gonocoxae, ventral view, scale bar = 0.5 mm; (F–I) D. sitesi: (F) male elytral apex, scale bar = 2 mm; (G–H) aedeagus, scale bar = 1 mm: (G) dorsal view; (H) lateral view; (I) gonocoxae, ventral view, scale bar = 1 mm; (J–M) D. spinosus: (J) male elytral apex, scale bar = 2 mm, (K–L) aedeagus, scale bar = 0.5 mm: (K) dorsal view; (L) lateral view; (M) gonocoxae, ventral view, scale bar = 0.5 mm.

FIGURE 7. Habitats of species of Gyrinini and Dineutini: (A–B) G. smaragdinus: (A) stream at Siriphum Waterfall, Doi Inthanon Natl. Park, Chiang Mai Province; (B) pond at Ban Buak Thoei, Chiang Mai Province; (C) D. australis, D. spinosus and D. unidentatus, pond at Sakaerat Environmental Research Station, Nakhon Ratchasima Province; (D) D. sitesi, Tum Din Stream, Thung Salaeng Luang Natl. Park, Phitsanulok Province; (E) D. spinosus, Huay Sae Stream, Ubon Ratchathani Province; (F–G) D. unidentatus, ponds at Ban Kho, Khon Kaen Province; (H) P. marginatus, Lam Takong Stream, Nakhon Ratchasima Province.

FIGURE 8. (A–B) Distributions of species of Dineutini and Gyrinini in Thailand.