Laccobius (s. str.) shengshanensis, Peng & Ji & Bian, 2019

Peng, Yunfei, Ji, Lanzhu & Bian, Dongju, 2019, Description of Laccobius (s. str.) shengshanensis sp. n. from China (Coleoptera: Hydrophilidae), Zootaxa 4691 (2), pp. 197-200 : 197-200

Laccobius (s. str.) shengshanensis sp. n.

Type locality. China, Heilongjiang Province, Heihe County, Shengshan National Nature Reserve , 126°46'08"E, 49°36'44"N, 385m.

Type material. Holotype, ♂ (IAECAS), labeled: " China, Heilongjiang Province, Heihe County, Shengshan National Nature Reserve , 126°46'08"E, 49°36'44"N, 385m, 2017.09.06, Leg. Peng", " Holotype, Laccobius shengshanensis sp. n. " [red printed label] . Paratypes (5 exs.): 1♂ 1♀ (IAECAS), labeled: " China, Heilongjiang Province, Mohe, Xing’an, 25 th Station , 123°35'54"E, 53°19'05"N, 349 m, 2017.09.03, Leg. Peng" ; 1♂ 2♀ (IAECAS), labelled:" Heilongjiang Province, Great Khingan, Tahe , 124°10'09"E, 53°13'22"N, 353m, 2017.09.03, Leg. Peng". All paratypes are labeled with a respective red printed paratype label .

Description. Total length 2.2–2.5 mm (holotype 2.4 mm); maximum width 1.2–1.4 mm (holotype 1.3 mm). Total length / total width ratio = 1.8. Body oval, moderately convex, with broadest width in anterior third of elytra, evenly narrowed posteriad ( Fig. 1 ).

Head. Labrum blackish brown, slightly convex at anterior margin, closely adhering to clypeus; surface densely punctured, anteriorly with stiff white setae. Clypeus and frons shiny black, preocular pale spots completely absent, surface with irregular, sparsely arranged fine punctures, punctures slightly impressed but larger than labral punctures, each puncture with decumbent white seta; microsculpture absent. Clypeus nearly 2.5× as wide as long, deeply emarginated anteriorly; frontoclypeal suture scarcely apparent. Eyes oval, moderately large, occupying 1/3 side margin of head. Inter-ocular distance ca. 3.1x diameters of eye. Ventral surface black, except the brown maxillae. Mentum slightly rugulose with fine punctures. Postmentum smooth, gula granulate. Maxillary palpi yellowish; palpomere 3 inflated, palpomere 4 darker at apex, asymmetrical, straight medially and convex laterally. Labial palpi yellowish. With 8 antennomeres, antennomeres 1–5 yellowish, antennal club (antennomeres 6–8) dark brown; antennomere 1 longer than antennomeres 2–4 combined; antennomere 5 asymmetrical, oval in ventral view, crescent-shaped and emarginate in dorsal view; antennal club loose, bearing densely arranged setae.

Thorax. Pronotum transverse, slightly impressed sublaterally, 0.44× as long as wide; black with yellowish lateral margins; yellow area about 0.5× as wide as posterior margin of eye along base, sometimes yellow edge vaguely defined from black disc; surface densely punctured, without micro-sculpture; punctures coarse and dense. Scutellum shield equilaterally triangular, black, with few punctures. Prosternum black, tectiform, with longitudinal keel. Mesoventrite with longitudinal, anteriorly arrow-shaped keel.

Elytra. Black on disc, yellowish along lateral margins, lateral pale stripe slightly widening anteriorly, very narrow at middle, then widening posteriorly, ca. 1.2× as long as wide, Elytral punctation consisting of fine setiferous punctures (some bearing a white seta) arranged in ca. twenty longitudinal rows, all punctures alike, with almost equally broad intervals. Parasutural furrow absent. Microsculpture absent. Epipleura ending at level of metafemora. Metaventrite with decumbent pubescence, which are absent from a small medio-posterior area.

Legs. Coxae and trochanters dark brown, femora dark brown except apical part, tibiae and tarsi yellowish brown. Femora with thin punctures, profemora pubescent at base 1/3. Tibiae with ranges of spines more developed on outer margin, and the spines on mesotibiae more developed; metatibiae slightly curved, distinctly longer than pretibiae and mesotibae. Tarsal natatory setae nearly absent. Tarsi with five tarsomeres; protarsomere 5 long, nearly 3× as long as other protarsomeres; mesotarsomere 1 is very short, mesotarsomeres 2 and 5 longer than other mesotarsomeres; metatarsomeres similar to mesotarsomeres. Claws shortly arcuate. Male with basal 2 protarsomeres dilated.

Abdomen. Venerates wrinkled, sparsely punctured and pubescent; pubescence denser on ventrites 1–5 than on ventrite 6.

Aedeagus. Total length 0.65 mm. Parameres nearly 1.8x as long as phallobase. Phallobase 1.2x as long as wide. Median lobe (without apophyses) nearly as long as parameres, slim at basal 2/3, then gradually broad, apices truncate, with one small angle at each side. Parameres gradually narrowing from base to basal 2/3, outer edge almost parallel, then slightly constricted, distal 1/3 extended outwards, inner-edge of apices with an indentation ( Fig. 1 e–f).

Biology. All known specimens were collected in an aquatic situation, living underwater in the sand at the edge of a pool ( Fig. 2 ).

Differential diagnosis. This new species is very similar to L. cinereus Motschulsky, 1860 in habitus from Kyrgyzstan, Russia and Mongolia and Liaoning province in China, but it can be distinguished by the apex of median lobe truncate, distal third of parameres oriented externally, and apices of parameres with an indention at inner edge, while in L. cinereus , the apex of median lobe round, the parameres are nearly parallel to median lobe, and apices of parameres expanded.

Etymology. This species name refers to Shengshan National Nature Reserve in which this new species was found.

Distribution. So far known only from the type locality in Heilongjiang Province, China.

Remarks: the key to the species of the subgenus Laccobius (s. str.) ( Gentili, 1995) could be modified as following:

7 Pronotum and basal part of elytra strongly shagreened, elytra pointed at tips...................................... 7a

7’ Pronotum more weakly shagreened, elytra not shagreened; broadened, oval; elytra usually rounded apically............. 8

7a Pronotum and basal part of elytra narrower and parallel-sided, the apex of median lobe round, the parameres are nearly parallel to median lobe, and apices of parameres expanded........................................ L. cinereus Motschulsky

7b Pronotum and basal part of elytra not narrower and parallel-sided, the apex of median lobe truncate, distal third of parameres oriented externally, and apices of parameres with an indention at inner edge.................... L. shengshanensis sp. n.

Figures

FIGURE 1. Laccobius (s. str.) shengshanensis sp. n. a–c: general habitus (a: dorsal view; b: lateral view; c: ventral view). d: meso- and metaventrites, e and f: aedeagus (e: dorsal view; f: lateral view).

FIGURE 2: Type locality of Laccobius (s. str.) shengshanensis sp. n. Heilongjiang Province, Heihe County, Shengshan National Nature Reserve.