Maechidius macrosoma Prokofiev 2022, new species
Creators: name: Prokofiev, Artem M.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Melolonthidae
Maechidius
Maechidius macrosoma

description: Maechidius macrosoma Prokofiev, new species
Fig. 7
Type material. Holotype, male (Fig. 7A): “D. N. Guinea 201 / Etappenberg 850 m 2.-8.xi.12 / Kais. Augustafl. Exp. / Bürgers S.G.” (ZMHB).
Description of the holotype. Total body length 10.5 mm, greatest width 5.7 mm. Dark reddish-brown, forebody darker, glossy; elytra alutaceus; 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 short but conspicuous, pointed, laterally directed, separated from lateral sides of labroclypeus by distinct incision, reflexed; canthus broadly rounded. Dorsal surface of labroclypeus punctured and setose similarly to frons, but punctures smaller and setae shorter. Underside of labroclypeus rather densely setose. Frons slightly impressed inward of eye, deeply and densely punctured; punctures large, annular, setigerous; intervening spaces much narrower than diameter of punctures. Setae erect, moderately long, ×1.5–2.0 diameter of puncture; a few longer and stiffer setae along inner margin of eye. Pronotum transverse, with anterior margin concave and bisinuate; anterolateral angles strongly protruding, acute, surface of pronotum at their base weakly impressed. Pronotum widest at middle, with sides weakly convex and smoothly converging anteriad and shallowly but distinctly concave posteriad; basal margin smoothly and regularly convex; posterolateral angles straight. Lateral margins of pronotum sharply denticulate, with 20 blunt denticles; a moderately short seta (of same length as setae on disc) present between every two crenulae. Punctures and setation of pronotum similar to those on head, but puncturation denser and intervening spaces very narrow, ridge-like, and setae adpressed. Most punctures on forebody with dense microscopical velvety pubescence. Hypomeron separated from prosternum by moderately high straight carina bearing moderately long setae; antennal pockets weak. Punctures of hypomeron much shallower and smaller than on disc of pronotum, but setae of same length, adpressed; intervening spaces variable, microreticulate and matt anteriorly and laterally, becoming smooth and glossy near forecoxae. Scutellar shield apically rounded, with moderately deep annular punctures bearing long (×2–3 diameters of corresponding puncture) adpressed setae; intervening spaces somewhat variable, distinctly microreticulate, matt. Elytra weakly widened posteriad, subtruncate apically, lacking longitudinal carinae. Punctures of elytral disc narrow, incision-shaped; intervening spaces commensurable with length of punctures, somewhat wrinkled and distinctly microreticulate, silky; setae semi-erect, ×1.5–2 length of corresponding punctures. Pygidium with weak impressions along midline and at basilateral corners; punctures large, annular, moderately shallow; intervening spaces distinctly smaller than diameter of punctures, microreticulate, matt; setae semi-erect, ×2.0–2.5 diameter of corresponding puncture, becoming slightly longer toward apex. Thorax with moderately large annular punctures becoming denser laterally, disc of metasternum impunctate along midline; intervening spaces on mesosternum distinctly microreticulate and matt, on metasternum very finely microreticulate to smooth, shining; setae adpressed, ×2.0–2.5 diameter of corresponding puncture. Abdominal ventrites densely but slightly irregularly punctured, punctures similar to those on metasternum, setae longer; intervening spaces distinctly microreticulate, silky. Ventral profile of abdomen weakly concave. Protibia (Fig. 7B) widened distally, with two longitudinal carinae dorsally and two short triangular apical teeth diverging at nearly right angle; basal tooth untraceable; protibial spur absent. Metatibial spurs pointed, straight; lower spur slightly longer and broader than upper one.Tarsomeres not elongated; three basal metatarsomeres bearing a band of brush-like setae along their ventrolateral margins (Fig. 7C). Tarsal claws with pulvilli. Aedeagus and spiculum gastrale, as on Figs. 7D–G; parameres symmetrical, each bearing a short anteriorly directed process at base; spiculum gastrale strongly bent.
Female unknown.
Differential diagnosis. The new species is keyed to M. hirtipes Arrow, 1941 or M. subcostatus Heller, 1895 in Telnov (2020) (the key is ambiguous for separation of these species), but aedeagus of both compared species is very different (Telnov 2020: figs. 620–622, 724–725); furthermore, the new species lacks the longitudinal carinae on elytral disc (Figs. 7A, 8). In the new species, the long brush-like setae are present on the first three metatarsomeres, while in the compared species those are confined to the first metatarsomere only. The aedeagus of the new species is most similar to that in M. brocki Telnov, 2020 and M. penicilliger, new species, but both the compared species differ in the absence of the anteriorly directed ventral process at the base of parameres, and both are very different externally, particularly in the shape of the male labroclypeus, in the pronotal sides more excavate at their bases, in the presence of the longitudinal elytral carinae and the male’s protibial spur, and in the longer setation of the body. Maechidius macrosoma, new species can be further distinguished from M. brocki in the bidentate male protibia with more divaricate apical teeth and in the presence of brush-like setae along the ventral margin of first three basal metatarsomeres, and from M. penicilliger, new species in the distinctly microreticulate (vs. glossy) elytra and in the absence of small protuberances with thickened setae on the two anteriormost abdominal ventrites. The body size of the holotype is larger than in any compared species, but a single specimen known does not allow to exclude the possible variations.
Etymology. The species name (meaning large-bodied in Greek) reflects the larger size of the holotype and only known specimen in comparison with similar species.
description: Published as part of Prokofiev, Artem M., 2022, New species and records of Maechidius Macleay, 1819 from New Guinea (Coleoptera: Scarabaeidae: Melolonthinae), pp. 445-462 in Zootaxa 5205 (5) on pages 454-456, DOI: 10.11646/zootaxa.5205.5.3, http://zenodo.org/record/7318489