Enochrus (Methydrus) limbourgi, Jia, Fenglong & Lin, Renchao, 2015

Jia, Fenglong & Lin, Renchao, 2015, Additions to the review of Chinese Enochrus, with description of a new species (Coleoptera, Hydrophilidae, Enochrinae), ZooKeys 480, pp. 49-57 : 50-52

Taxon classification Animalia Coleoptera Hydrophilidae

Enochrus (Methydrus) limbourgi sp. n. Figs 3-4, 12-15, 20

Type material.

Holotype: male (SYSU): China, Jiangxi Province, Jing’an county, Zaodu town, Nanshan village, 29.01°N, 115.16°E, 315m, 19.vii.2014, light trap, Ren-Chao Lin leg.

Diagnosis.

Size 7.3 mm. Head without preocular spots (Fig. 3). Second maxillary palpomere pronouncedly and extensively darkened except extremity, apical palpomere yellowish brown, not dark apically (Fig. 12). Prosternum with a low carina medially (Fig. 14). Head, pronotum and elytron with fine and very dense punctures (Fig. 13). Scutellum with a few coarse and strong punctures. Claws of anterior and middle legs in male distinctly strongly and angularly curved, bearing a smaller basal tooth. Fifth abdominal ventrite with apical emargination fringed with stiff yellowish setae (Fig. 15). Aedeagus with parameres curved outwards apically. Median lobe oval broadened basally, abruptly narrowed ca. half, apical half much narrower than parameres, sharp apically (Fig. 20)

The new species is most similar to Enochrus (Methydrus) eubenangeei Watts, 1998 which is endemic species to Australia in its large size, black color, punctures on dorsal surface, mesoclaws thickened basally and bent in male, median lobe of aedeagus oval, broadened basally, parameres obliquely truncate apically. In contrast to Enochrus eubenangeei Watts, Enochrus limbourgi is characterized by: pronotum and elytron with distinct pale yellow-brown margin; prosternum with a low distinct median carina; elytra with five series of punctures; claws of male middle tarsi bent, broadly thickened basally; aedeagus with parameres broad, obliquely truncate apically and weakly curved outwards subapically (parameres similar to Enochrus (Methydrus) aliciae Watts, 1998 in form).

The size of this species is the largest in the known species of Enochrus (Methydrus) from the Oriental and southern Palearctic Regions. The median lobe of aedeagus is clearly different from other known Asian species. It is very easy to distinguish this species from other species in Asia by size, punctures and aedeagus. Compared with Chinese species, it is closed to Enochrus japonicus Sharp by size and colour. It can easily be distinguished from the latter by pronotum and elytra with denser ground punctures, serial punctures on elytra less strong and less coarse, mesosternal process strongly depressed laterally, median lobe of aedeagus oval broadened basally, parameres sharp apically.

Description.

Form and Colour. Body length 7.3 mm, body width 4.0 mm. Body oval, moderately convex. Dorsum of head, pronotum and elytron black, with lateral margins of pronotum and elytron distinctly yellow-brown. Antennae yellow-brown with club black. Maxillary palps with second maxillary palpomere pronouncedly and extensively darkened except extremity (Fig. 12); third palpomere slightly darkened medially, apical palpomere yellowish brown, not dark apically (Fig. 12). Labial palps yellow, not darkened apically. Venter, including legs, black, tarsomeres yellow-brown.

Head. Antennae with scape ca. as long as antennomeres 2-3 combined. Maxillary palps subequal to the width of head anterior to eyes; apical palpomere about three-quarters of penultimate in length (Fig. 12). Anterior margin of clypeus straight medially. Labrum with a median row of setiferous systematic punctures, distinctly coarser than the surrounding ground punctation. Frons and clypeus with ground punctation dense and coarse, distance between ground punctures 1.0 –1.2× the width of one puncture; setiferous systematic punctures well pronounced, ca. 3 × as large as ground punctures. Mentum subquadrate, with anterior margin slightly depressed medially, not emarginate anteriorly (Fig. 4), ground punctures moderately coarse.

Thorax. Ground punctation on pronotum and elytron similar to that on head, distance between ground punctures 1.0 –1.2× the width of one puncture. Elytron with five rows of serial punctures (including lateral series) clearly larger than surrounding ground punctation; without short series of punctures in front of sutural stria, the third series with a few punctures that are distant between punctures. Sutural stria present in posterior half of elytra. Prosternum not tectiform, with a low distinct median carina (Fig. 14) and a transverse groove behind anterior margin. Mesoventrite with a median process which is strongly impressed laterally and with a backwardly pointing projection, rising to level of mesocoxae, apex of the projection with a few long setae. Metaventrite with a very indistinct elongate oval glabrous area posteromedially, longer than wide; glabrous area slightly more than half the total length of the metaventrite. Mesofemora densely pubescent except in apical fifth (Fig. 15). Metafemora with pubescence as in mesofemora (Fig. 15). Posterior tarsomeres with a fringe of long swimming-hairs dorsally. Anterior claws in male strongly and angularly curved, bearing smaller basal tooth; claws of male middle tarsi of similar shape as those of anterior tarsi, but slightly weakly angularly curved; posterior claws only slightly curved, without basal tooth.

Abdomen. Ventrites uniformly and densely pubescent. Fifth (apical) abdominal ventrite with apical emargination fringed with stiff yellowish setae (Fig. 15).

Aedeagus. Phallobase about 1.2 × as long as parameres. Parameres broad, longer than median lobe, abruptly truncate and bent outwards apically. Median lobe oval broadened basally, abruptly narrowed ca. half, apical half much narrower than parameres, sharp apically (Fig. 20).

Etymology.

The specific name is after Dr. Pol Limbourg, an entomologist in Intitute Royal des Sciences Naturelles, Brussels, Belgium, who helped us a lot when senior author studied types of Enochrus in d’Orchymont’s collection in Brussels.

Distribution.

China (Jiangxi), known only from the type locality.

Habitat.

The holotype was collected by light trap.