Amiserica basisymmetrica Ahrens, Fabrizi & Liu, 2021

Ahrens, Dirk, Liu, Wangang, Pham, Phu Van & Fabrizi, Silvia, 2021, An overview on the genus Amiserica Nomura, 1974 (Coleoptera: Scarabaeidae: Melolonthinae: Sericini), Zootaxa 5050 (1), pp. 1-63 : 23-25

Amiserica basisymmetrica Ahrens, Fabrizi & Liu , new species

Figures 6A–D , 13

Type material examined. Holotype: ♂ “N. Vietnam, 30.iii.1995, Sapa (Chapa), 1600 m, Schintlmeister & Siniaev leg. / Coll. P. Pacholátko Invt. No. / Sericini Asia spec. 440” ( CP) . Paratypes: 3 ♂♂ “ Vietnam, Yen Bai Prov., Mu Cang Chai Distr. Che Tao commune, Muc Cang Chai Species & Habitats Cons. Area 21.7641°N, 104.0430°E, / around Cong Troi ( Gate to Heaven ) Pass , 2040 m, upper montane evergreen forest, at light, 24–30.IX.2016 (#14) Otto Merkl & Phu Pham Van” ( HNHM) .

Description of the holotype. Length: 7.6 mm, length of elytra: 5.1 mm, width: 4.4 mm. Body oval, dark brown, surface dull, labroclypeus shiny, antenna yellowish brown, dorsal surface almost glabrous.

Labroclypeus narrowly subtrapezoidal, widest at base, lateral margins convex and convergent to moderately rounded anterior angles, lateral border and ocular canthus producing a distinct obtuse angle; anterior margin weakly emarginate medially, margins weakly reflexed; surface flat and shiny, finely and coarsely, densely punctate, with numerous long erect setae; frontoclypeal suture indistinctly impressed and angled medially; smooth area anterior to eye 1.5 times as wide as long. Ocular canthus moderately long and narrow, finely and sparsely punctate, with a short terminal seta, equal to 1/3 of ocular diameter. Frons dull, shiny in anterior half, finely and moderately densely punctate, with sparse long setae beside eyes and behind frontoclypeal suture. Eyes small, ratio of diameter/interocular width: 0.56. Antenna with ten antennomeres, club with four antennomeres, slightly reflexed externally, twice as long as remaining antennomeres combined. Mentum elevated and flattened anteriorly.

Pronotum widest at base, lateral margins in basal half straight and weakly convergent anteriorly, in anterior part strongly curved and convergent to moderately produced and moderately sharp anterior angles, posterior angles nearly rectangular; anterior margin distinctly convex, with the marginal line widely interrupted at middle; basal margin without marginal line; surface with dense and coarse punctures each bearing a minute seta, otherwise glabrous; anterior and lateral borders sparsely setose; hypomeron carinate, basal margin of hypomeron not produced ventrally. Scutellum triangular, apex sharp, with coarse and moderately dense punctures, punctures with minute setae only.

Elytra oblong, widest at posterior third, striae distinctly impressed, with fine and dense punctures; intervals moderately convex, with fine, evenly and moderately dense punctures, punctures with minute setae only, on penultimate lateral interval with a few long erect fine setae; epipleural edge moderately strong, ending at strongly rounded external apical angle of elytra, epipleura densely setose, apical border chitinous, without a rim of microtrichomes.

Ventral surface dull, with coarse and dense punctures, glabrous except minute setae in punctures. Metacoxa only laterally with a few robust longer setae. Abdominal sternites finely and densely punctate and minutely setose, each sternite with a distinct transverse row of coarse punctures each bearing a short, robust seta. Mesosternum between mesocoxae as wide as mesofemur. Ratio of length of metepisternum/metacoxa: 1/1.53. Pygidium weakly convex and dull, with coarse, dense punctures and a few fine, long setae on posterior half.

Legs moderately slender; femora finely densely and coarsely punctate and glabrous, except for minute setae of punctures, with two longitudinal rows of setae; anterior margin of metafemur acute, with an adjacent continuously serrated line, ventral posterior margin weakly widened in apical half but not serrate, dorsal posterior margin completely smooth as well. Metatibia slender and moderately long, widest at apex, ratio width/length: 1/3.85, sharply carinate dorsally, the basal group of spines shortly behind the middle, the apical one at 4/5 of metatibial length, basally with a few single spines in punctures; beside dorsal margin with a continuously serrated line until the distal group of spines being convergent with dorsal margin at apex, between serrated line and dorsal finely sparsely punctate; lateral face longitudinally convex, with moderately dense and coarse punctures bearing each a minute seta; ventral margin serrated, with three fine and long, equidistant robust setae; medial face impunctate; apex interiorly near tarsal articulation shallowly concavely sinuate. Tarsomeres dorsally impunctate, ventrally with short, sparse setae. Metatarsomeres ventrally with a strongly serrated ridge, laterally not carinate; first metatarsomere little shorter than following two tarsomeres combined and a quarter of its length longer then dorsal tibial spur. Protibia moderately long, bidentate, protarsal claws symmetrical, basal tooth of inner claw simply but sharply truncate at apex.

Aedeagus: Fig. 6A–C . Habitus: Fig. 6D . Female unknown.

Variation. Length: 6.4–7.6 mm, length of elytra: 4.8–5.1 mm, width: 3.8–4.4 mm.

Diagnosis. Amiserica basisymmetrica Ahrens, Fabrizi & Liu , new species differs from A. antennalis and all other species by the distinctly shorter antennal club and the smaller eyes as well as by the symmetric phallobase.

Etymology. The name of the new species is derived from the combined Latin words, basis (base) and symmetricus (symmetric), with reference to the symmetric phallobase.

Figures

FIGURE 6. A–D: Amiserica basisymmetrica Ahrens, Fabrizi & Liu, new species (holotype); E–H: A. strnadi Ahrens, Fabrizi & Liu, new species (holotype). A, E: Aedeagus, left side lateral view; C, G: Aedeagus, right side lateral view; B, F: Parameres, dorsal view; D, H: Habitus (not to scale). Scale: 0.5 mm.

FIGURE 13. Distribution of the species of the Amiserica rufidula group, part 1.