Maechidius astrolabius 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 : 447-448

Maechidius astrolabius Prokofiev , new species

Fig. 2

Type material. Holotype, male ( Fig. 2A ): “N. Guinea / Astrolabe-B. / Rhode ” ( ZMHB).

Description of the holotype. Total body length 7.5 mm, greatest width 4.2 mm. Dark reddish-brown, glossy from above; antennae and palpi rusty-brown, much lighter than body; setation pale. Antennae 9-segmented, club 3-lamellate. Labroclypeus broadly concave anteriorly, its lateral margins strongly sinuous in both dorsal and lateral views; anterolateral angles distinctly protruding, reflexed; canthus angulate. Dorsal surface of labroclypeus densely punctured, punctures deep, annular, approximately 1.5 times less than those on frons; setation apparently worn. Underside of labroclypeus minutely punctured, punctures setigerous. Frons weakly convex. Punctures on frons very large and deep, ovoid, with dense microscopical velvety pubescence; intervening spaces very narrow, convex, smooth and glossy; setae (largely worn) moderate in length, ×0.75–1.5 length of puncture. Pronotum transverse, with anterior margin concave and anterolateral angles strongly protruding, acute. Sides of pronotum smoothly converging anteriad in anterior third, almost parallel-sided in posterior two-thirds; basal margin convex, more strongly before scutellar shield; posterolateral angles obtuse. Lateral margins of pronotum distinctly crenulate, with 16 crenulae becoming slightly larger in middle third of side-length; a short seta present between every two crenulae (often worn). Punctures and setation of pronotum similar to those on head, but punctures on disc slightly larger; intervening spaces very narrow, ridge-like, smooth and glossy, forming an allusion of longitudinal ridges in oblique light. Hypomeron separated from prosternum by moderately high emarginate carina bearing moderately long setae; antennal pockets conspicuous but not deep. Punctures of hypomeron large, annular, setigerous; setae as long as punctures; intervening spaces much smaller than diameter of puncture, shagreened, matt. Scutellar shield deeply and densely punctured, apically pointed; intervening spaces much smaller than diameter of punctures, shagreened, matt. Elytra moderately widened posteriad, broadly rounded apically, with vague traces of two longitudinal carinae between sutural carina and humeral umbones. Punctures of elytral disc long and narrow, incision-shaped, becoming smaller toward side-margins; intervening spaces wrinkled, finely reticulate, glossy, generally larger than length of punctures; setae adpressed, not surpassing length of corresponding punctures. Pygidium flat, with large and dense annular punctures; intervening spaces very narrow, shagreened, matt; setae semi-erect, ×1.0–1.5 diameter of puncture, becoming longer toward apical margin. Thorax and abdominal ventrites shagreened and matt except the smooth and glossy disc of metasternum; punctures annular, larger on disc of metasternum and in middle third of abdominal ventrites, becoming smaller laterally; intervening spaces generally smaller than diameter of punctures; setae not or slightly surpassing diameter of corresponding punctures. Ventral profile of abdomen slightly convex. Protibia ( Fig. 2B ) widened distally, with two longitudinal carinae dorsally and three outer teeth, basal tooth very weak; protibial spur long and pointed, straight along most of its length but slightly curved at base. Metatibial spurs with blunt tips, lower spur only slightly longer than upper one and weakly curved. All tarsomeres short, first two metatarsomeres of same length. Tarsal claws with pulvilli. Aedeagus, as on Figs. 2C–D ; parameres somewhat asymmetrical, with overlapping tips. Spiculum gastrale was damaged (apparently thin and flat).

Female unknown.

Differential diagnosis. This species is keyed to the couplet 4 in Telnov (2020) and resembles M. acutus ( Narakusumo & Balke, 2019) , M. humeralis Heller, 1914 , and M. paralellicollis Moser, 1920 in many respects. However, M. astrolabius , new species can be easily separated from all aforementioned species by the larger-sized ovoid punctures on the head and pronotum covered with the fur-like micropubescence (vs. annular and lacking micropubescence) and by the bigger denticles along the lateral sides of the pronotum (16 vs. 19–25 in the compared species). It is more similar to M. acutus and M. humeralis by the presence of the vague longitudinal carinae on elytral disc and by the transversely wrinkled intervening spaces between the punctures on the elyta (both absent in M. paralellicollis ) but differs from all these species in the shape of aedeagus. The aedeagus of the new species is most similar to that in M. acutus ( Narakusumo & Balke, 2019: figs. 1e–f), differing mainly by its asymmetrical parameres.

Etymology. This species is named from its type locality, Astrolabe Bay.

Figures

FIGURE 2. Holotype of Maechidius astrolabius Prokofiev, new species. (A) dorsal view; (B) protibia; (C) aedeagus, lateral view; (D) parameres, dorsal view. Scale bars: (A, B) 1.0 mm; (C, D) 0.5 mm.