Grouvellinus sagittatus, 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 : 92-94

Taxon classification Animalia Coleoptera Elmidae

Grouvellinus sagittatus sp. n. Figures 3-4, 26-28

Type materials.

Holotype, male: "China: Jiangxi / Ganzhou, Longnan / County, Jiulianshan; 24°37'N 114°32'E, 560 / m 2009.10.10, Leg. Bian / & Tong (16)"(white label); "HOLOTYPE / Grouvellinus / sagittatus sp. n."(red label). Paratypes: 2 males, 2 females: "CHINA: Jiangxi, / Ganzhou City, Longnan / County, Jiulianshan; Downstream of loc. 16; / 2009.10.10; leg. Bian & / Tong (loc. 17)" (white label); "PARATYPE / Grouvellinus / sagittatus sp. n." (red label).

Diagnosis.

This species is characterized by its small size (<2 mm), dorsum sparsely pubescent, and metasternum with two small pits on the median suture; penis ends with an arrow, and parameres gradually narrowed from base towards apex.

Description.

Body length 1.75 mm, body width 0.80 mm. Body shape elongate obovate, subparallel (Figs 3-4). Dorsal surface brown to dark brown, with strong bronze luster; elytra paler than pronotum. Ventral surface brown to dark brown, femora and tibiae brown, antennae, mouth parts, and tarsi yellowish-brown.

Head smooth and shining, covered with long pubescence; small circular punctures sparsely impressed. Clypeus surface smooth, sparsely punctate and pubescent; labrum smooth, surface of disc weakly punctate and pubescent, and densely pubescent laterally.

Pronotum 1.2 times as broad as long; broadest at basal 2/5. Surface smooth and shining, accompanied with long adpressed pubescence; small circular punctures sparsely and superficially impressed. Basal sub-lateral carinae present on basal 2/5, but only slightly raised, feebly converging anteriorly; an oblique impression on each side extending from apical end of carina to anterior angle; base with two elongate oval impressions in front of anterior angles of scutellum.

Elytra 1.6 times as long as broad, 1.4 times as broad as pronotum; sides subparallel in basal 2/3, and then tapering to separated rounded apex. Strial punctures larger and deeper on disc, but becoming finer and shallower on apical declivity; intervals convex, smooth and shining, 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, subquadrate, strongly rimmed, with transverse, smooth elevation at base; surface almost without punctures and pubescent on disc (Fig. 4). Disc of metasternum flat, smooth and shining, sparsely punctate, with two small pits on median suture, one is longitudinal which on the middle of metasternum, and the other one is transverse which is in front of the posterior margin; sub-lateral region densely pubescent, with two rows of coarse punctures on each side, one is oblique with very large punctures which begin at anterior margin laterally and end up in front of the 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 few small punctures; sub-lateral regions densely pubescent; distal 2/3 of ventrite V granulate.

Male genitalia (Figs 26-28): long and slender, 605 µm in length; penis extends beyond parameres, distinctly narrowed from base toward apex, arrowed at the tip; ventral sac developed, longer than parameres. Parameres gradually narrowed from base to apex in dorsal view.

Females similar to males, but disc of metasternum not flat, distinctly elevated.

Distribution.

China: Jiangxi.

Etymology.

The specific name comes from the Latin word " sagittatus " meaning “arrow-shaped” and refers to the inflated apical portion of penis.

Remarks.

Grouvellinus sagittatus sp. n. is similar to Grouvellinus orbiculatus sp. n. in body size, habitus, interval 8 with a carina, and two small pits on median suture, but can be distinguished from the latter by sparser punctures on pronotum, penis ends with an arrow, and parameres gradually narrowed from base to apex in dorsal view.