Neoserica rufoplagiatoides Ahrens & Pham, 2021

Ahrens, Dirk & Pham, Phu Van, 2021, Additions to the Neoserica calva group from continental South East Asia (Coleoptera: Scarabaeidae: Melolonthinae: Sericini), Zootaxa 5032 (3), pp. 357-378 : 374-376

Neoserica rufoplagiatoides Ahrens & Pham , new species

Fig. 5E–I

Type material. Holotype: ♂ [ Laos] “ Luang Prabang Ban Saloueun 9.III.1920 R.V. de Salvaza / Brit. Mus. 1921-89./ 709 Sericini Asia spec.” ( BMNH) . Paratypes: 5 ♂♂, 11 ♀♀ [ Laos] “ Luang Prabang Ban Saloueun 9.III.1920 R.V. de Salvaza / Brit. Mus. 1921-89./ 709 Sericini Asia spec.” ( BMNH, ZFMK) .

Description of the holotype. Body length: 5.0 mm, length of elytra: 3.0 mm, width: 2.9 mm. Body oval, orange brown, head, meso- and metasternum dark brown, pronotum and elytra yellowish brown, the first with two dark spot beside anterior margin, the latter with dark sutural interval and posterior lateral intervals including humerus, scutellum dark as well, legs and antennal club yellowish brown, dorsal surface dull and except frons nearly glabrous, labroclypeus and anterior two thirds of frons shiny.

Labroclypeus subtrapezoidal, wider than long, widest at base; lateral margins convex and convergent towards moderately rounded anterior angles; anterior margin weakly emarginate medially; margins weakly reflexed but medially slightly elevated; surface flat and shiny, finely and densely punctate, with a few single setae anteriorly. Frontoclypeal suture distinctly incised and bent medially. Smooth area anterior to eye small, weakly convex, as wide as long. Ocular canthus short and wide (equal to 1/2.5 of ocular diameter), finely and densely punctate, with a single terminal seta. Frons on anterior quarter shiny, finely and irregularly, densely punctate, with a few long single setae beside eyes, otherwise glabrous; on posterior three quarters dull (with toment), finely and sparsely punctate, glabrous. Eyes very small, ratio diameter/interocular width: 0.4. Antenna with ten antennomeres, club with four antennomeres and straight, 1.2 times as long as remaining antennomeres combined. Mentum elevated and slightly flattened anteriorly. Labrum transverse, short, not produced medially, with weak median sinuation.

Pronotum subtrapezoidal, widest at base; lateral margins in basal half almost straight and subparallel, in anterior half evenly convex, strongly convergent anteriorly; anterior angles strongly produced and sharp; posterior angles blunt; anterior margin weakly convex, with a fine complete marginal line; surface densely and finely punctate, with minute setae in punctures; lateral and anterior sparsely setose; basal margin without marginal line; hypomeron distinctly carinate basally. Scutellum long, with fine, dense punctures, glabrous.

Elytra short, widest at middle; striae weakly impressed, finely and moderately densely punctate; intervals weakly convex, with sparse, fine punctures concentrated along striae, impunctate medially, with minute setae in punctures; penultimate lateral interval with a few single short setae. Epipleural edge fine, ending at moderately curved external apical angle of elytra; epipleura densely setose; apical border chitinous, without microtrichomes (visible at 100x magnification).

Ventral surface dull, finely and densely punctate. Metasternum except long setae on disc nearly glabrous, sparsely covered with minute setae in punctures. Metacoxa glabrous, with a few single setae laterally. Abdominal sternites finely and densely punctuate, glabrous except minute setae in punctures, with a transverse row of coarse punctures each bearing a robust long seta. Mesosternum between mesocoxae as wide as mesofemur. Ratio of length of metepisternum/metacoxa: 1/1.4. Pygidium weakly convex and dull, sparsely punctate, without smooth midline, with a few long setae beside apical margin.

Legs moderately slender. Femora with two longitudinal rows of setae, finely and sparsely punctate. Metafemur dull and sparsely finely punctate; anterior margin acute, behind anterior margin without serrated line; posterior margin in apical half serrated ventrally and moderately widened at apex; posterior margin finely serrated dorsally, glabrous. Metatibia moderately slender and short, widest at apex, ratio of width/length: 1/2.7; dorsal margin moderately carinate, with two groups of spines; basal group at one third, apical group at two thirds of metatibial length; in basal half with a few short robust setae in single robust punctures with serrated margin; external face longitudinally convex, finely and sparsely punctate; ventral margin finely serrated, with three robust, equidistant setae; medial face impunctate, glabrous, apex bluntly truncate interiorly near tarsal articulation. Tarsomeres ventrally with sparse, short setae, not carinate laterally, impunctate dorsally; metatarsomere 1 distinctly longer than dorsal metatibial spur and little shorter than following two tarsomeres combined. Protibia moderately long, bidentate, bluntly widened laterally before basal tooth; anterior claws symmetrical, basal tooth of inner claw sharply truncate at apex.

Aedeagus: Fig. 5E–H . Habitus: Fig. 5I .

Variation. Body length: 4.4–5.0 mm, length of elytra: 3.0– 3.3 mm, width: 2.8–3.0 mm. In some specimens (mostly females, but also some males) the dark spot on pronotum are not present. Female: eyes as large as in male; antennal club composed of three antennomeres, as long as remaining antennomeres combined.

Diagnosis. Neoserica rufoplagiatoides Ahrens & Pham , new species differs from all other species of the Neo- serica calva group by its distinct bicoloured dorsal pattern and the lacking microtrichomes on apical margin of elytra, as well, of course by the shape of aedeagus (see Fig. 5E–H ).

Etymology. The name of the new species is derived from the composed Latin name rufoplagiata (species name) and the Greek suffix - oides (similiar), with reference to the external similarity to Maladera rufoplagiata (Fairmaire, 1893) .

Figures

FIGURE 5. A–D: Neoserica sharkeyi Ahrens & Pham, new species (holotype); E–I: N. rufoplagiatoides Ahrens & Pham, new species (holotype). A, E: Aedeagus, left side lateral view; C, H: Aedeagus, right side lateral view; B, G: Parameres, dorsal view; F: Aedeagus, dorsal view; D, I: Habitus (not to scale). Scale: 0.5 mm.