Metallactus affinis Jacoby 1907
Creators: name: Sassi, Davide
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Chrysomelidae
Metallactus
Metallactus affinis

description: Metallactus affinis Jacoby, 1907
(Figs 9; 20)
Metallactus affinis Jacoby, 1907: 849; Clavareau, 1913: 92; Blackwelder, 1946: 640.
Type material. As Jacoby (1907) claimed in describing the species that “... the more so as there are two exactly similar specimens before me.”, the two specimens housed in BMNH must be the complete type series of the species. The typification has been made as follows. LECTOTYPE: ♂, glued, detached abdomen on the same label, aedeagus on a separate label, // “Lagos S. Brasil ” [white label, handwritten] // “Jacoby Coll. 1909-28 a.” [white label, handwritten] // “ Metallactus affinis Jac. Type” [blue label, handwritten] // “ Syntype ” [white with blue border, printed] //” Metallactus affinis Jacoby, 1907 LECTOTYPUS D. Sassi des.” [red label, printed] // (BMNH). Paralectotype: 1♀, glued, same data as the lectotype // “ Metallactus affinis Jacoby, 1907 PARALECTOTYPUS D. Sassi des.” [red label, printed] // (BMNH).
Type locality. In my opinion, the name of the type locality is misspelled on the syntypes label, and Jacoby reported it in such way in the description of the species. The correct locality should be considered Lages (Santa Catarina, Brazil).
Further material examined. BRAZIL: Santa Catarina Lages Hochland Fruhstorfer (8, MNHUB); Santa Catarina (2, MNHUB); Santa Catarina Nova Teutônia [Seara] 22.X.1948 F. Plaumann (1, NHMB); Lages Prov. S.ta Catharina J. Michaelis 1887 (2, MNHN); Santa Catarina Theresopolis [ambiguous datum] 1888 Frustorfer (1, USNMNH).
Distribution. Brazil.
Diagnosis. A Metallactus of medium size. Similar to M. albipes as regard the coloration but considerably smaller and perceptibly flattened in dorsal view. In M. affinis tibiae are constantly and completely black and definitely curved (which is not so obvious in other species of the M. albipes group), punctuation of the dorsal parts is coarser and almost completely confused on elytra. M. affinis is also particular in having ocular distance rather short in males. The aedeagus is slender, with a more distinct apex than in M. albipes, because the sides of the aedeagus are slightly arched. In lateral view the aedeagal tube is fairly depressed in the middle of the ventral profile. M. corruptus has similar size and dorsal coloration but differs in having abdominal ventrites partly black (fully yellowish in M. affinis), tibiae almost straight and partly yellowish, weaker dorsal punctation and a more cylindrical look in dorsal view. Because of the presence of additional oblique pronotal impressions in front of usual ones, the species recalls M. languidus, from which it differs in the strongest punctuation, the shape of the aedeagus, especially in lateral view and, again, for the more flattened overall look.
Description of male. Habitus in Fig. 9 a–b (LT). BL = 4.3–4.7 mm, BW = 2.6–2.8 mm, PL = 1.1 mm, PW = 2.3 mm. Interocular distance 7.0–7.2% of BL.
Head black with a x-shaped yellow spot extending on lower part of frons and clypeus. Labrum brownish with lighter lower rim. Surface dull with scattered shallow punctures. Yellow parts slightly raised. Setosity almost absent, being only few scattered whitish setae on clypeus and close to inner ocular rim. Mid-cranial suture apparent, quite short, not extended to vertex. First five antennomeres brownish, the subsequent totally darkened, dull and more diffusedly setose.
Pronotum yellow with a transverse subrectangular or slightly curved black stripe not reaching margins, devoid of constrictions, with a small median posterior lobe just in front of scutellum. Pronotal shape elliptical with lateral margins quite large, regularly arcuate and maximum width slightly behind half of length. Posterolateral impressions apparent, rounded, small but quite deep, rather forwardly placed in respect to posterior margin. Surface dull to moderately lustrous with scattered, rather coarse punctation, sparser on disc.
Scutellum completely black, moderately raised, subsquared with truncated apex. Some scattered rather long whitish setae and very minute and sparse shallow punctures.
Elytra yellow with black pattern consisting of three pairs of roughly rounded spots reaching neither suture nor lateral margin. Spots of posterior pair fairly different in size, being the outer one much smaller. Spots of each pair sometimes fused together to form an irregular transverse band. Surface dull with punctation quite strong and dense, partly arranged in almost regular rows markedly apparent even on apical clivus. Intervals partly raised.
Surface of pygidium yellow, smooth, covered by sparse shallow punctures and pale setae.
Inferior parts with thorax partly yellow with black pattern more or less extended on posterior half of hypomera and on external part of meso and metathorax. Often a triangular black patch on midline of metathorax. Abdomen completely yellow. All ventral surface covered by scattered yellowish setae, quite regularly arranged. Punctuation regularly distributed and shallow, coarser on hypomera and outer part of metathorax. Prosternal process longitudinally sunken, with apex rounded to triangular with a little blunt terminal tooth. Prosternal surface covered with long dense pale setae. Legs yellow with tarsi, fore tibiae and apical half of mid and hind tibiae black.
Fifth abdominal ventrite with median depression rather deeply impressed, lengthened, smooth, bald, impunctate and posterior margin weakly notched. Median lobe of aedeagus (Fig. 9 c–e) cylindrical with apex short, blunt, weakly bent ventrally. Sides of apex slightly concave so that apex fairly distinct from aedeagal tube in ventral view. Aedeagal ventral profile weakly concave in its median part in lateral view.
Endophallus (Fig. 9 f–g) with sclerite I well sclerotized, large, with well developed, long, robust, blunt, straight denticle. Dorsal spicule well developed, cylindrical, pointed, distinctly bent backwards. Sclerite II, abruptly bent near base. Sclerite III rather squat with arch slender, evenly thickened. Branches of sclerite IV slightly longer than sclerite III in the folded up structure, robust, evenly thickened, with rounded apex and surface fairly rugose.
Female. BL = 5.2–5.4 mm, BW = 3.3–3.5 mm, PL = 1.4–1.5 mm, PW = 2.8–2.9 mm. Interocular distance 11.2–11.5% of BL. Females differs from males in lateral margin of pronotum more angulate, with maximum width slightly back to the middle. Elytral lateral margins slightly larger and curved, so that maximum width is not close to humeral calli, but close to the middle.
Fifth abdominal ventrite in females with rather deep, subelliptical pit. Spermatheca (Fig. 9h) with basal branch of vasculum straight, evenly thickened, slightly longer than upper branch. Apex compact, almost straight, shortly pointed. Ampulla stocky, just on tip of basal branch or slightly shifted on dorsal side. Duct uniform in thickness, slender, coiled, but coils fairly loose, obliterated in the last portion. Insertion on bursa copulatrix rather squat, piriform. Rectal apparatus (Fig. 9 k–m) with dorsal sclerites quite stout with apodemes large, hyaline or slightly pigmented on outer rim, bent upwards and leaning against rectum. Ventral sclerite large, deep, with curved posterior margin, slightly tapered on sides, almost evenly pigmented or fairly lighter on median part, with apodemes shortly crenulate on margin, 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 82-83, DOI: 10.11646/zootaxa.4413.1.2, http://zenodo.org/record/3066636