Grouvellinus orbiculatus, Bian, Dongju & Sun, Haibin, 2016

Bian, Dongju & Sun, Haibin, 2016, A key to Grouvellinus Champion, 1923 from mainland China with descriptions of two new species (Coleoptera, Elmidae), ZooKeys 623, pp. 89-104 : 91-92

Taxon classification Animalia Coleoptera Elmidae

Grouvellinus orbiculatus sp. n. Figures 1-2, 23-25

Type material.

Holotype: male, "CHINA: Jiangxi / Ji’ an City, Suichuan/ County, Duiqian Town; 26°20'N 114°17'E, 228 / m, 2009.10.02, leg. / Bian & Tong (loc. 10)" (white label); "HOLOTYPE / Grouvellinus / orbiculatus sp. n." (red label). Paratypes: 3 males, 4 females, the same data as holotype. 4 males, 2 females: "CHINA: Jiangxi / Ji’ an City, Suichuan / County, Caolin Town; 26°16'N 114°22'E, 228 / m, 2009.10.03, leg./ Bian & Tong (loc. 11)" (white label); "PARATYPE / Grouvellinus / orbiculatus sp. n." (red label). 1 male: "CHINA: Jiangxi / Ganzhou City, Shangyou / County, Wuzhifeng Town; 25°57'N 114°05'E, 554 / m, 2009.10.05., leg. / Bian & Tong (loc. 12)"(white label); "PARATYPE / Grouvellinus / orbiculatus sp. n." (red label).

Diagnosis.

This species is characterized by its small size (<2 mm), dense punctures on pronotum, sparse pubescence on the elytra, and the metasternum with two small pits on median suture; the penis end has a rounded expanded apex, and the parameres are distinctly narrowed at basal 1/3 in dorsal view.

Description.

Body length 1.70 mm, body width 0.80 mm. Body shape elongate obovate, subparallel (Figs 1-2). Head black, pronotum and elytra brown, femora and tibiae dark brown. Antennae and tarsi yellowish brown.

Head smooth, covered with long pubescence; surface with small circular punctures sparsely and superficially impressed. Clypeus surface smooth, weakly punctate, lateral sides sparsely covered with long pubescence. Labrum smooth, weakly punctate and densely pubescent laterally.

Pronotum 1.2 times as broad as long, broadest at basal 2/5, surface smooth and shining, covered with adpressed pubescence; small circular punctures densely impressed. Sub-lateral carinae present on basal 2/5, feebly raised and feebly converging anteriorly; an oblique impression on each side extending from the end of carina to anterior angle. Base with two elongated oval impressions in front of anterior angles of scutellum.

Elytra 1.5 times as long as broad, 1.4 times as broad as pronotum; sides subparallel in basal 2/3, and then gradually narrowed to separated rounded apex. Strial punctures larger and deeper in basal half separated by 0.5-1.0 diameter; punctures becoming smaller and widely separated (2-5 times diameters); intervals slightly convex, and each interval with one or two rows of small punctures and pubescence; intervals 2-4 slightly elevated at base; interval 8 carinate.

Process of prothoracic ventrite approximately1/3 as broad as pronotum, distinctly rimmed; basal 2/3 disc smooth and shining, slightly elevated, apex somewhat truncate (Fig. 2). Disc of metasternum broadly impressed, surface smooth and shining, weakly punctate, and two small pits present on median suture; sub-lateral area of metasternum densely pubescent; metasternum with two rows of punctures on each side, one is oblique consisting of very large punctures which begin at anterior margin laterally and end up in front of metacoxae, the other one consisting of moderate-sized punctures is in front of posterior margin. Middle regions of ventrites I–IV smooth and shining, with small punctures sparsely distributed, and sub-lateral regions densely pubescent; middle region of ventrite V at basal 1/3 is similar to ventrites I–IV, elsewhere on ventrite V densely pubescent and sparsely granulate.

Male genitalia (Figs 23-25) long and slender, about 690 µm in length. Penis distinctly surpasses parameres, gradually narrowed from base to distal portion, apex expanded ending up with broadly rounded apex; ventral sac with lateral sides weakly sclerotized, surpassing the parameres. Parameres robust at base, distinctly narrowed at basal 1/3 in dorsal view.

Female similar to male, but disc of metasternum not broadly impressed, slightly elevated.

Distribution.

China: Jiangxi.

Etymology.

The specific name comes from the Latin word " orbiculatus " and refers to the rounded apical portion of penis.

Remarks.

Grouvellinus orbiculatus sp. n. is similar to Grouvellinus sagittatus sp. n. in body size, habitus, interval 8 on elytra with a carina, and two small pits on median suture of metasternum, but can be distinguished from the latter by its denser punctures on pronotum, penis ends with expanded rounded apex, and parameres distinctly narrowed at basal 1/3.