Metallactus guarani Sassi 2018, sp. nov.
Creators: name: Sassi, Davide
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Chrysomelidae
Metallactus
Metallactus guarani

description: Metallactus guarani sp. nov.
(Figs 19; 27)
Etymology. The species is named after the indigenous Guaraní people. The word guarani is a latinized noun in the nominative singular, standing in apposition to the generic name (art. 11.9.1.2. I.C.Z.N., 4th edition).
Type material. HOLOTYPE: ♂, glued, aedeagus extracted and glued on the same label bearing the specimen, detached abdomen on the same label, // “Republique Arg ne Territ re des Misions” [white label, printed] // “ Coll on Le Moult Naturaliste Paris ” [white label, printed] // “Collection Wagner” [red label, printed] // “ Coll. Achard Mus. Pragense” [white label, printed] // “ Metallactus guarani sp. nov. HOLOTYPUS D. Sassi des.” [red label, printed] // (NHMP). PARATYPES: 7♂ 13♀♀, same data of the holotype (NHMP, DSPC, MSNM); 2♀♀, // “Republique Arg ne Territ re des Misions” [white label, printed] // (MNHUB). All paratypes provided with additional label: // “ Metallactus guarani sp. nov. PARATYPUS D. Sassi. des.” [red label, printed] //.
Type locality. Misiones (Argentina).
Distribution. Argentina.
Diagnosis. A Metallactus of medium size. It can be assigned to the group with a more transverse pronotal outline, even though this character is particularly difficult to set out in this taxon. The more similar in size and dorsal colour pattern are M. corruptus, M. bellatrix and M. languidus. In comparison with these latter species, M. guarani is well characterized by abdominal ventrites (always completely) and other ventral parts (often completely) yellow. Inferior parts are more or less extensively black in M. corruptus and M. bellatrix and completely black in M. languidus. Besides, the new species distinctly differs from M. corruptus and M. languidus in the shape of aedeagus, which is slightly swollen on apical third. In addition, the aedeagal tube also differs for the presence of two weak oblique bulges (Fig. 19c) near the basal foramen on the ventral surface. The bulges can be observed both in ventral and lateral view. In the lateral view the profile is slightly depressed in the middle, rising perceptibly towards the base and towards the apex. Pronotal punctation is much sparser and shallower on disc than in M. corruptus. M. guarani can be distinguished from M. bellatrix, in addition to the ventral colouration pattern, by the pronotum less transverse with less angulate and narrower lateral margins. Besides, in M. bellatrix the elytral punctation is almost completely irregular on basal half (with clues of striae in M. guarani).
Description of male. Habitus in Fig. 19 a–b (HT). BL = 5.6–5.8 mm, BW = 3.0– 3.1 mm, PL = 1.8 mm, PW = 2.6–2.7 mm. Interocular distance 9.1–10.4% of BL.
Head yellow with vertex and insertion of antennae black. Surface with few scattered punctures, more concentrates on frons. Frons with a short well definite narrow longitudinal groove. First five antennomeres yellowish, subsequent antennomeres totally darkened, dull and more diffusedly setose.
Pronotum yellow with two trefoil stripes on sides not reaching lateral margins. Lobes of each stripe turned backwards. In paler specimens (Fig. 19 a–b) stripes more or less reduced, in some cases split into little rounded spots or totally obliterated. Pronotal shape shortly elliptical with lateral margins thin, almost regularly converging forwards and thus barely visible from above. Posterolateral impressions very poorly marked, in correspondence of which the posterior margins scarcely thickened. Surface moderately shining with scattered, poorly impressed punctation, sparser on disc where it can be completely obliterated in most of the surface.
Scutellum black to almost completely yellow, distinctly raised with truncated apex, finely setose and very minutely and sparsely punctuated.
Elytra yellow with three transverse pairs of black rounded spots. First pair of spots on humeral calli and on side of post-scutellar area, the second just behind the middle and the third one, smaller, on elytral apex. Spots sometimes reduced or partly obliterated. Cylindrical in shape, parallel-sided, very weakly flattened on disc with postscutellar area not raised and humeral calli prominent, impunctate. Surface moderately shiny with shallow punctures partly arranged in irregular rows, vanishing on elytral apex. Intervals flat.
Pygidium yellow, smooth, covered by sparse shallow punctures and whitish setae.
Inferior parts almost completely yellow, only meso and metathorax sometimes partly darkened. Surface coarsely punctured with scattered yellowish setae, denser close to median line. Prosternal process normally shaped, longitudinally grooved with apex blunt and surface covered with coarse punctures and long, dense whitish setae. Legs yellow with tarsi and apex of tibia more or less darkened.
Fifth abdominal ventrite with a median depression barely impressed, smooth, glabrous, impunctate; posterior margin weakly notched. Median lobe of aedeagus (Fig. 19 c–e) slightly enlarged on apical half, with apex barely separate from aedeagal tube. Hairy dents barely distinguishable, bearing few, scattered, short setae. Aedeagal surface with two weak oblique ventral bulges (Fig. 19c) close to basal foramen. In lateral view profile somewhat depressed in the middle, distinctly rising towards base (in correspondence of ventral bulges) and toward apex.
Endophallus (Fig. 19 f–g) with sclerite I evenly pigmented, large, with denticle prominent, blunt. Dorsal spicule well developed in size, pigmented, cylindrical with a rounded tip. Sclerite II well developed, generally abruptly bent at base. Arch of sclerite III shaped like a bird head, being quite straight on basal half, with apex pointed and faintly but perceivably convex along the basal half of upper rim. Branches of sclerite IV slightly shorter than sclerite III in the folded up structure, quite stout, weakly bent to almost straight, evenly thickened, with rounded, slightly symmetrical apex and surface fairly rugose.
Female. BL = 6.0– 6.3 mm, BW = 3.5–3.7 mm, PL = 1.9–2.1 mm, PW = 3.0– 3.2 mm. Interocular distance 13.6–14.2% of BL.
Fifth abdominal ventrite in females with rather deep, rounded pit. Spermatheca (Fig. 19h) with vasculum scarcely pigmented, with short regularly tapered upper branch, apex compact, sometimes slightly curved downwards. Lower branch almost straight to vaguely bent backwards. Ampulla not or weakly pigmented, slightly shifted on dorsal side of vasculum. Duct quite short, uniform in thickness, slender, coiled, but coils obliterated in the last portion. Insertion on bursa copulatrix slightly swollen, curved and pigmented. Rectal apparatus (Fig. 19 km) with dorsal sclerites laterally not projected beyond rectus, slender, shortly tapered towards median line and apodemes large, hyaline, bent upwards and leaning against rectum. Ventral sclerite large, ellipsoidal, deep, slightly tapered on sides, less pigmented in middle, with rounded apodemes barely crenulate on margin and slightly wider than rectum.
description: Published as part of Sassi, Davide, 2018, Revision of the Metallactus kollari species-group with a new diagnosis of the genus (Coleoptera: Chrysomelidae: Cryptocephalinae), pp. 57-110 in Zootaxa 4413 (1) on pages 103-104, DOI: 10.11646/zootaxa.4413.1.2, http://zenodo.org/record/3066636