Grouvellinus acutus, Bian & Jäch, 2018

Bian, Dongju & Jäch, Manfred A., 2018, Revision of the Chinese species of the genus Grouvellinus Champion, 1923 (Coleoptera: Elmidae). The G. acutus species group, Zootaxa 4387 (1), pp. 174-182 : 175-176

Grouvellinus acutus sp. nov.

( Figs 1–2 , 9–11 )

Type material. Holotype ( IAECAS), male: “ CHINA: FUJIAN, Longyan \ Xiaochi (20 km W Longyan ) \ Meihua Shan , 650m, 30.1.1997 \ leg. Ji & Wang ( CWBS 263 )” . Paratypes: 5 males (IAECAS: 3, NMW: 2): same label data as holotype; 2 males (NMW): same label data as holotype except “leg. H.Schönmann”; 12 males ( IAECAS: 3, NMW: 9): “ CHINA: FUJIAN, Longyan \ Shizhong, Shangfang Shan \ 850m, 31.1.1997 \ leg. Ji & Wang ( CWBS 264 )” ; 1 male ( NMW): “ CHINA: FUJIAN, Yong'an \ 2 km SW Xiyang, 350m \ Ziyungdong Shan , 24.1.1997 \ leg. H.Schönmann ( CWBS 254 )” ; 1 male ( NMW): “ CHINA: FUJIAN, Yong'an \ 4 km SW Xiyang, 400 m \ Ziyungdong Shan , 25.1.1997 \ leg. Ji & Wang ( CWBS 257 )” ; 1 male ( NMW): “ CHINA, SE-Guangxi \ Distr. Yulin \ Liuwan Mts. SW Yulin ǀ 16.11.1993 \ 350–400m \ leg. Schönmann (20) [= CWBS 42 ]” ; 2 males ( IAECAS, NMW): “ CHINA: SE-Guangxi \ Distr. Yulin \ Liuwan Mts. SW Yulin | 17.11.1993 \ Kuishan, 300m \ leg. Schönmann (22) [= CWBS 44 ]”.

Diagnosis. Males of this species can be distinguished from the other species of this group by the combination of the following characters: presence of a distinct pair of admedian metaventral carinae, and conspicuous broad sclerotized, usually hooked appendage at apex of hind tibia; apex of penis abruptly attenuate, acute; in lateral view, parameres broad, constricted at basal 1/5, in dorsal view median margins conspicuously sinuous.

Description. Head black, pronotum brown. Elytra brown or black, base and declivity with yellowish-brown to dark red spot of variable size; spots generally larger and paler in specimens from Guangxi. Ventral surface dark brown, legs brown, antennae yellowish-brown.

BL: 1.65–1.85 mm, BW: 0.90–1.00 mm. Body obovate, subparallel ( Figs1–2 ).

Head densely granulate and sparsely pubescent. Surface of clypeus similar to that of frons. Labrum smooth and shining, sparsely punctate and pubescent.

PL: 0.48–0.53 mm, PW: 0.62–0.70 mm. Pronotum broadest at base, sparsely punctate, distal 2/3 of disc usually smooth and shining, basally and sublaterally usually densely granulate and pubescent; in basal half granules densely arranged along midline, almost resembling a low median carina. Sublateral carinae present on basal 0.4, subparallel. Oblique impression extending from apex of carina to anterior angle. Base with a pair of very small oval impressions in front of anterior angles of scutellum.

EL: 1.17–1.32 mm. Elytral strial punctures moderately large in basal half, separated by 1.5 – 2.0 times their diameters; punctures becoming smaller in distal half, separated by 2–3 times their diameters. Non-carinate intervals slightly convex or almost flat, each with a row of setae.

Surface of prosternal process sparsely granulate, basal half of disc slightly elevated; sides distinctly rimmed, apex broadly rounded. Metaventrite densely granulate and sparsely pubescent, in males narrowly impressed along median suture and each side of impression with a longitudinal carina extending from base to basal 0.7. All ventrites densely granulate and sparsely pubescent. Male hind tibia with conspicuous sclerotized, often hooked apical appendage.

Aedeagus ( Figs 9–11 ): 0.58 mm long. Penis slightly longer than parameres, gradually tapering from base towards apex, then abruptly attenuate subapically, forming an acute tip. Parameres robust, rather densely setose in apical part; in lateral view distinctly constricted at basal 1/5; dorsal margin conspicuously sinuous.

Female: All females, which were collected together with the holotype and the paratypes (see below, under Discussion) lack carinae on the metaventrite, which is less deeply impressed than in the males; hind tibiae without appendage.

Distribution. So far known only from Fujian and Guangxi ( China).

Etymology. The epithet is derived from the Latin adjective “ acutus ” (acute) and refers to the abruptly attenuate, acute apex of the penis.

Figures

FIGURES 1–4. Habitus, 1–2 dorsal and ventral view of Grouvellinus acutus sp. nov., male, holotype; 1a G. acutus sp. nov., hooked apical appendage on male hind tibia; 3–4 dorsal and ventral view of G. denticulatus sp. nov., male, holotype. Scale bar= 0.5 mm.

FIGURES 9–14. Male genitalia of 9–11 Grouvellinus acutus sp. nov., holotype; 12–14 G. denticulatus sp. nov., holotype. 9, 12 ventral view; 10, 13 dorsal view; 11, 14 lateral view. Scale bar = 0.1 mm.