Metallactus abstersus D. Sassi 2025
Creators: name: Sassi, Davide
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Chrysomelidae
Metallactus
Metallactus abstersus

description: Metallactus abstersus (Suffrian, 1866)
= Metallactus incultus Suffrian, 1866 syn. nov.
Description of lectotype (the only male available). Habitus in fig. 2a–b (LT). BL = 5.0 mm, BW = 3.0 mm, PL = 1.6 mm, PW = 2.6 mm. Interocular distance 13.0 % of BL.
Head: black with blurred, trefoil-shaped yellow spot between antennal insertions. Labrum yellow. Surface of vertex and upper part of frons smooth, almost impunctate, punctation denser on clypeus and along inner rim of eyes, setosity almost missing on vertex and frons, thick and adpressed on clypeus and along inner eye margins. Mid-cranial suture obliterated. Upper lobes of eyes well separated along median lines. Ocular lines narrow, strictly adhering to ocular rim, marked by rows of small punctures. Ocular canthus deep, rounded, scarcely setose. Antennomeres highly missing, only basal third preserved, first one blackish, the following two yellowish.
Pronotum: yellow with two comma-shaped, black spots on sides of median line. Two additional, smaller black spots situated externally to first ones, also comma-like with concavity directed forward. Pronotal outline scarcely transverse, roughly square, lateral margins narrow, almost straight, surface regularly convex. Posterolateral impression apparent but shallow, so that posterior margin not particularly swollen toward sides. Surface moderately lustrous with scattered, rather strong punctation, denser on sides, almost obliterated on disc.
Scutellum: completely black, moderately raised, truncated at apex. Surface smooth, impunctate with few, short, regularly scattered whitish setae.
Elytra: completely yellow with suture and apical margin narrowly infuscate. Elytral outline cylindrical, parallel-sided. Surface regularly convex with lateral margins narrow, scarcely visible from above. Scutellar area faintly raised. Humeral callus scarcely prominent, not punctured. Punctation shallow and minute, quite irregularly arranged in rows in particular in basal half. Intervals flat.
Pygidium: piceous, smooth, dull, covered by sparse, rather shallow punctures and pale setae.
Underside: ventral surface black, matt, covered with long, thick, adpressed, whitish setae, except shiny, scarcely setose, sparsely punctured posterior part of hypomera. Prosternal process narrow, longitudinally grooved, roughly rounded on apex. Surface of prosternal process covered with long, thick, semi-erect whitish setae. Fifth abdominal ventrite with a deep, heart-shaped, bald, impunctate median depression and deeply notched posterior margin.
Legs: black with anterior margins of anterior femora yellow.
Male genitalia. Median lobe of aedeagus (Fig. 2h–m) subcylindrical with apex blunt, relatively short, flattened, spoon-shaped in ventral and dorsal view, almost straight in lateral view. Setose depressions shifted to very lateral border of ventral surface, in form of narrow, lengthened callosities, with very short, scattered setae. Ventral surface bearing two shallow but clearly visible rounded depressions on its apical section, delimiting a large, squat, pointed median bulge whose distal margin, in lateral view, is slightly convex. Endophallus not examined.
Female. BL = 6.3 mm, BW = 3.9 mm, PL = 1.8 mm, PW = 3.3 mm. Interocular distance 15.9 % of BL.
In females, formerly described as Metallactus incultus, the interocular distance is larger, whereas they are very similar regarding the coloration. Small differences can be observed: in a single specimen (the LT of M. incultus, fig. 2g) the humeral callus is black, and an oblique black spot is also present at the middle of elytral surface. This specimen is also characterized by a closer and more irregular arrangement of the elytral punctation. However, it would be futile to propose a diagnostic pattern based on the few available specimens, which still show evident chromatic variability.
The pit on the fifth abdominal ventrite in females is large and deep. The bottom of the pit is glabrous, matt, impunctate but covered by tiny wrinkles. The vasculum of the spermatheca (Fig. 5d) is moderately pigmented, sickle-shaped with straight, not swollen proximal lobe. The distal lobe is short, mildly swollen at middle, with an acute apex slightly bent downwards. The ampulla is not pigmented, short, sitting just at basal apex of vasculum. The duct and sperm gland insertions are perceptibly distinct. The duct is very long, uniform in size, slender, floppy, strictly coiled, with its insertion on the bursa copulatrix forming a rigid, well pigmented sleeve.
description: Published as part of Sassi, Davide, 2025, Revision of the Metallactus minax Suffrian, 1866 species-group (Coleoptera: Chrysomelidae: Cryptocephalinae), pp. 71-86 in Zootaxa 5583 (1) on pages 78-80, DOI: 10.11646/zootaxa.5583.1.3, http://zenodo.org/record/14798002