Helochares (Hydrobaticus) hainanensis, Dong & Bian, 2021

Dong, Xue & Bian, Dongju, 2021, Three new species and two new records of Helochares (Hydrobaticus) MacLeay 1871 from China (Coleoptera: Hydrophilidae: Acidocerinae), Zootaxa 4950 (1), pp. 166-180 : 168

Helochares (Hydrobaticus) hainanensis sp. n.

( Figs. 1–4 )

Material examined. Holotype (IAECAS): 1 male: “ CHINA: Hainan Province, / Qionghai City, Wanquan Town , | 2007.11.14, 19°11’N, 110°23’E, / 38 m, leg. Bian & Tong”.

Diagnosis. This new species is similar to Helochares (Hydrobaticus) minor in habitus, but can be distinguished by the following characteristics: (1) dorsal punctures on head, pronotum and elytra are slightly smaller and shallower than in H. minor ( Figs. 1, 4 ); (2) elytra with ten rows of impressed serial punctures, not forming striae ( Fig. 1 ); (3) serial punctures are slightly larger than interstrial punctures ( Fig. 1 ); (4) interstriae on elytra wide and flat ( Fig. 1 ); (5) aedeagus with median lobe very slender and spine-like in appearance, as long as parameres ( Fig. 3 ); (6) parameres wider in basal 0.85, then suddenly narrowed, apices narrowly rounded ( Fig. 3 ).

Description. Habitus as in Figs. 1–2 . BL: 4.5 mm, BW: 2.3 mm. Body oval, moderately convex. Head brown, pronotum and elytra yellowish-brown, apices of tarsal claws black, ventral side dark brown to black.

Head ( Fig. 4 ). Labrum brown, anterior margin straight. Clypeus brown, broad, anterior margin strongly emarginate, moderately expanded laterally in front of eyes, with somewhat rounded lateral margin; densely punctate, lateral area with slightly sparse punctures. Eyes slightly bulging, somewhat prominent; several setae anteriad to eyes. Frontoclypeal suture distinct. Systematic punctures small and distinct. Antennae with nine antennomeres, yellowish-brown; club loosely articulated, densely pubescent. Maxillary palpi moderately long and slender, about 1.2 times long as the width of head, yellow, the second palpomere curved inwards. Mentum and submentum with coarse punctures and wrinkles.

Thorax ( Fig. 1–2, 4 ). Pronotum about as twice wider than long; distinctly and densely punctate; anterior and posterior angles broadly rounded. Anterior margin slightly projected anteriad in mid-length, with a row of setae. Lateral margin slightly lighter in color; with a median dark mark closed to anterior margin and some larger punctures. Posterior margin slightly corrugate, with a transverse groove; near the posterior margin with a pair of small pits which overlap with black marks ( Figs. 1, 4 ). Prosternum ( Fig. 2 ) slightly bulging at the middle, not carinate; protruding posteriorly; pubescent and rugulose. Mesoventrite strongly convex at postmedian area. Metaventrite pubescent, with fine punctures, somewhat convex at middle portion. Elytra ( Fig. 1 ) together slightly wider than pronotum, widest behind midpoint; with scutellary stria and ten impressed series of punctures, but not striate; interstrial punctures small and dense, as on head and pronotum; serial punctures slightly larger and deeper than interstrial punctures; interstriae wide and flat; posterior region with slightly sparse punctures. Scutellum triangular, with sparsely fine punctures.

Legs. Femora dark brown, tibiae and tarsi brown, apices of tarsal claws black. Femora densely pubescent with apical fifth glabrous. Tarsi with some dense white scattered setae.

Abdomen. All visible ventrites with dense pubescences and fine punctures; apex of the fifth ventrite strongly emarginate which is wider than deep ( Fig. 2 ).

Aedeagus ( Fig. 3 ). Slender, 1.1 mm long. Basal piece symmetrical, very short, about 0.15-times of the total length, the manubrium indistinct. Median lobe as long as parameres, very slender appearing as a long spine along its distal third; apophyses of median lobe extending beyond basal margin of basal piece. Parameres robust, wider in basal 0.85, then abruptly narrowed, apices narrowly rounded.

Distribution. Known only from the type locality in Hainan Province, China.

Etymology. Named after the type locality, Hainan Province, China.

Habitat ( Fig. 25 ). Slow flowing river, with pebbles, silt, deadwood and sides with short shrubs and fireweed.

Figures

FIGURES 1–4. Helochares (Hydrobaticus) hainanensis sp. n. 1–2. Habitus. 1. Dorsal view. 2. Ventral view. 3. Aedeagus. 4. Head and pronotum.

FIGURES 25–27. Habitat. 25. Wanquan Town, Qionghai City, Hainan Province (Helochares (Hydrobaticus) hainanensis sp. n.); 26. Wuzhifeng Town, Ganzhou City, Jiangxi Province (Helochares (Hydrobaticus) wuzhifengensis sp. n.); 27. Mangkuan Village, Baoshan City, Yunnan Province (Helochares (Hydrobaticus) tengchongensis sp. n.).