Maechidius addarcis Prokofiev, 2022

Prokofiev, Artem M., 2022, New species and records of Maechidius Macleay, 1819 from New Guinea (Coleoptera: Scarabaeidae: Melolonthinae), Zootaxa 5205 (5), pp. 445-462 : 446

Maechidius addarcis Prokofiev , new species

Fig. 1

Type material. Holotype, male ( Fig. 1A ): “ New Guinea / Doron xi.1921 / R. Neill Rothschild / B.M. 1939-I ” ( BMNH) . Paratypes: 3 females, same data as for the holotype ( BMNH) .

Description of the holotype. Total body length 8.5 mm, greatest width 4.2 mm. Dark reddish-brown with legs more reddish; antennae and palpi reddish; setation pale. Body (including dorsal surface of head but not labroclypeus) is almost completely covered with microscopical velvety pubescence. Antennae 9-segmented, club 3-lamellate. Labroclypeus broadly concave anteriorly, its lateral margins strongly bisinuate in both dorsal and lateral views; anterolateral angles small and pointed, triangular, weakly reflexed; canthus angulate. Dorsal surface of labroclypeus coarsely punctured, punctures deep, annular, with dense microscopical velvety pubescence; intervening spaces variable, smooth and glossy. Canthus is tightly covered with dense microscopical pubescence, with few moderately long erect setae. Underside of labroclypeus rather densely setose. Frons flat; punctures similar to those on labroclypeus, but much densely arranged; intervening spaces very narrow; setae erect to semi-erect, short, commensurable with diameter of punctures. Pronotum transverse with anterior margin concave and bisinuate; anterolateral angles acute; sides of pronotum broadly rounded in anterior two-thirds and deeply concave in posterior third; basal margin strongly convex; posterolateral angles almost straight. Lateral margins of pronotum crenulate, with about 20 poorly expressed crenulae, better developed along middle widest part of pronotum; a very short seta (often worn) present between every two crenulae. Pronotal punctures large, annular to hexagonal; intervening spaces very narrow; setation (largely worn) similar to that on head and elytra. Hypomeron separated from prosternum by moderately high emarginate carina bearing long setae; antennal pockets rather deep; punctures large, annular; intervening spaces generally smaller than punctures; setae moderately long in anterior half, becoming short, not surpassing diameter of puncture in posterior half. Scutellar shield apically rounded, with dense and rather coarse annular puncturation; setae probably worn. Elytra weakly widened posteriad, broadly rounded apically, with four weak longitudinal carinae splitting to a series of sparsely sitting granules (two rows between sutural margin and humeral umbo, third row running from humerus toward apical umbo, fourth one extending forward from apical umbo along lateral margin of elytron); sutural joint not elevated. Punctures of elytral disc narrow, incision-shaped; intervening spaces generally smaller than length of punctures; setae adpressed to semi-erect, not or hardly surpassing length of corresponding punctures. Pygidium flat, with shallow annular punctures; intervening spaces very narrow; setae semi-erect, similar to those on elytra. Thorax and abdominal ventrites with small and shallow annular punctures; intervening spaces smaller than diameter of punctures; setae adpressed, generally exceeding diameter of punctures in length on thorax and not surpassing it on abdominal ventrites. Ventral profile of abdomen slightly convex. Protibia ( Fig. 1B ) weakly widened distally, with two longitudinal carinae dorsally and two strong apical teeth directed outward; basal tooth weak. Protibial spur short, straight, somewhat inclined ventrally. Metatibial spurs short and straight, pointed; lower spur thicker and twice longer than upper one. Tarsomeres not elongated, setae not forming brush-like patches along their ventral margin. Tarsal claws with pulvilli. Aedeagus and spiculum gastrale, as on Figs. 1C–F ; parameres symmetrical, with tips rectangular, crossing each other in default position. Spiculum gastrale flat along most of its length, only the base of its shaft strongly reflexed ( Fig. 1F ).

Females. Total body length 8.0– 9.5 mm, greatest width 4.0– 4.5 mm. Secondary sexual differences not expressed except the comparatively shorter antennal lamellae, more pronounced basal tooth of protibia ( Fig. 1G ) and longer spurs on all tibiae. Metatibial spurs only slightly different in length, weakly clavate at tips. Sides of pronotum before posterolateral angles variably excavated. Longitudinal carinae on elytra variably developed, from continuous along almost whole length of elytra to expressed at their base and near umbones only.

Differential diagnosis. This species is keyed to the couplet 15 in Telnov (2020), but can be easily distinguished from both M. subcostatus Heller, 1895 and M. similis Telnov, 2020 by dense coating of microscopical velvety pubescence and in the unique shape of parameres with tips crossing each other in default position. It is superficially somewhat similar to the members of the former genus Paramaechidius or M. pauxillus group as of Telnov (2020) but can be easily differentiated from them by absence of the clavate setae on the dorsum, presence of the tarsal pulvilli in both sexes, the dorsally flat frons and different aedeagus.

Etymology. The species epithet is created from the Latin words ad (to) and arx (tip), due to the conjoining tips of the parameres.

Figures

FIGURE 1. Maechidius addarcis Prokofiev, new species. (A) dorsal view, holotype; (B) protibia, holotype; (C) aedeagus, lateral view, holotype; (D) parameres, dorsal view, holotype; (E) spiculum gastrale, dorsal view, holotype; (F) ditto, lateral view; (G) protibia, female paratype. Scale bars: (A, B, G) 1.0 mm; (C–F) 0.5 mm.