Metallactus multicolor D. Sassi 2022, n. comb.
Creators: name: Sassi, Davide
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Chrysomelidae
Metallactus
Metallactus multicolor

description: Metallactus multicolor (Jacoby, 1899) n. comb.
(Figs 4; 14)
Scolochrus multicolor Jacoby, 1899: 177.
Griburius multicolor Clavareau, 1913: 90 (catalogue); Blackwelder, 1946: 640 (catalogue).
Types. Jacoby (1899) did not mention the number of specimens under study. During this study two syntypes (both males) were located at MSNG and one (female) at BMNH. A lectotype is here designated as follows: Lectotype (by present designation): ♂, body, aedeagus and detached abdomen glued on the same card, // “ Pto 14 de Mayo G. Boggiani I.1897 ” [white label, printed] // “ Scolochrus multicolor Jac ” [blue label, handwritten] // “multicolor ♂ Jac.” [white label, handwritten] // “Typus” [white label, printed in red] // “Museo Civico di Genova” [green label, printed] // “ Griburius multicolor (Jacoby, 1899) (Scolochrus multicolor) LECTOTYPUS D. Sassi des.” [red label, printed] // “ Metallactus multicolor (Jacoby, 1899) D. Sassi det. 2021” [white label, printed] // (MSNG). Paralectotypes: 1♂, body, aedeagus and and detached abdomen glued on the same card, // “ Pto 14 de Mayo G. Boggiani I.1897 ” [white label, printed] // “Museo Civico di Genova” [green label, printed] // (MSNG); 1♀, glued, // “ Pto 14 de Mayo G. Boggiani I.1897 ” [white label, printed] // “ Scolochrus multicolor Jac ” [blue label, handwritten] // “Museo Civ. Genova” [orange label, printed] // “Jacoby Coll. 1909-28a.” [white label, handwritten] // “Cotype” [rounded white label with yellow border, printed] // (BMNH). Both paralectotypes labeled as follows: // “ Griburius multicolor (Jacoby, 1899) (Scolochrus multicolor) PARALECTOTYPUS D. Sassi des.” [red label, printed] // “ Metallactus multicolor (Jacoby, 1899) D. Sassi det. 2021” [white label, printed].
Type locality. Puerto 14 de Mayo (Chaco Boreal, Paraguay).
Additional material examined. (54 specimens examined). PARAGUAY: Puerto Pinasco 30 W Kilometro A. Wetmore Collector (1, USNMNH); Central Piquete Cue 9.X.1990 & 7.XI.1991 U. Drechsel (2, MSPC); Chaco Boreal 90 Km SE Filadelfia, 27.I.2008 S 23° 14´W59°12´100m lgt. Kradlekovà (1, DSPC); Chaco 130 Km NW Mariscal Esfigarribia 29.I.2008 J. Halada leg. (1, NHMP); Chaco Yalve Sanga V.1984 (1, FSCA); Asuncion Botanical Garden 2.I.1966 Leg. Mahunka (1, HNHMB); Pres. Hayes 42 Km NW Benjamin Aceval 6.II.1983 (1, ERPC); Dep. P.te Ayes Villa Ayes V.1992 (1, DSPC); Pres. Ayes ruta 9 km 344 116m 23.02S 59.15W 5.XII.2010 (2, MSPC). ARGENTINA: La Merced Reimoser (2, NMV); Chaco Resistencia XI.1945 Martinez (1, USNMNH); Chaco Resistencia 23.XII.1965 leg. Mahunka (1, HNHMB); Cordoba Fanti Sierra de Cordoba 11.I.1966 Mahunka (1, HNHMB); Chaco Sáenz Peña K. J. Hayward B. M. 1933-187 (4, BMNH); Chaco de Santiago del Estero Bords du Rio Salado Env. d’Icano E.R.Wagner XII,1909 (1, MNHN); Chaco de Santiago del Estero Bords du Rio Averyas E.R.Wagner XII,1909 (1, MNHN); Chaco de Santiago del Estero Bords du Rio Salado Paso de Don José 26 km N Icano E.R.Wagner XII,1910 (1, MNHN); Chaco de Santiago del Estero Env. D’Icano Mistol Paso E.R.Wagner 1918 (4, MHNH); Santiago del Estero Rio Salado ex coll. Achard (1, NHMP); Santiago del Estero Añatuya I.1944 coll. Monrós (1, USNMNH); Stgo. Estero Quimili III.1992 (2, DSPC); Formosa La Lomitas XI.950 Daguerre (1, USNMNH); Formosa Irigoyen X. 950 Daguerre (1, USNMNH); Formosa 2 km S Clorinda 26.I.1989 C. & L. O’Brien & G. Wibmer (1, BYU); Formosa Gran Guardia XII.1951 Coll. J Föester (1, USNMNH); Tucumán Guasapampa A. A. Ogloblin 1.XII.1942 (1, USNMNH); Salta Güemes II.1945 Martinez coll. Monrós (1, USNMNH); Salta Senillosa 1927 G. L. Harrington (1, USNMNH). BOLIVIA: Santa Cruz Santa Cruz 28.IX.1972 G. E. Bohart (8, BYU); Santa Cruz Lomas de Arena Biol. Park 10.II.1999 L. A. Stange (1, FSCA); Santa Cruz Prov. Chiquitos Santiago 700m IX.1959 (2, SMNS); Santa Cruz 9 mi. N Santa Cruz 28.III.1978 at night C. W. & L. O’Brien (2, ERPC); Santa Cruz 7 km S of Warnes 6.XII.1973 (1, AMNH); Santa Cruz 3 km N Brazilio 1750´malaise 18°06.82´S 63°10.51´W 27.II-8.III.1989 M Elrwin & F. Parker (1, BYU); Santa Cruz IX.1917 Exp. Lizer-Delétang to Bolivian Chaco ex coll. Achard (1, NHMP).
Distribution. Argentina (new), Bolivia (new), Paraguay.
Diagnosis. The species was described as belonging to genus Scolochrus (now Griburius), but the shape of the male genitalia, the morphology of the pronotal process, the ocular distance and the overall outline clearly suggest a transfer to genus Metallactus. The light dorsal pattern, almost always distinguishable in partly reddish (along elytral sides and, at times, pronotal sides) and partly yellow (pronotal midline, elytral apex, and sutural region) often allows to distinguish specimens of M. multicolor from the ones of the other species studied. The shape of the longitudinal elytral black stripe, sharply folded towards lateral margin at its posterior terminal is useful as well in the identification. Based on the colour pattern, the species that most resembles it, is M. taeniatellus, but in the latter the light elytral colour is always uniform yellowish or reddish, and not two-toned as M. multicolor. However, the shape of the aedeagus median lobe gives the conclusive evidence.
Description of male. Habitus in Fig 4 a-b (LT). BL = 3.9–4.1 mm, BW = 2.5 mm, PL = 1.5–1.6 mm, PW = 2.2–2.3 mm. Interocular distance 7.7–9.8 % of BL.
Head yellow, with mid-cranial suture partly darkened. Vertex, ocular canthus, antennal insertion, and clypeal edge blackish. Labrum light brown. Head surface with scattered, weakly impressed setigerous punctures, fairly darkened at bottom. Mid-cranial groove shallow but evident. Ocular lines narrow, strictly adhering to ocular rim, marked by a narrow line of setose punctures. Ocular canthus sparsely punctured with sparse, short, appressed setae. Antennomeres 2-5 yellowish, moderately lengthened, 6-11 totally darkened, dull, flattened and more diffusely setose (Fig. 4h).
Pronotum black with two large yellow stripes extending over lateral margins and outer fourth of anterior margin, another yellow stripe along median line, tapering forwards and expanded along the posterior margin. Pronotal shape elliptical, with regularly convex surface. Lateral margins thin, almost not visible in dorsal view, evenly curved with maximum width just behind half length. Surface subopaque with scattered, small punctation, denser and more impressed on sides, sparser on disc. Posterolateral impressions reduced to very short oblique grooves close to posterior margin.
Scutellum black, moderately raised, trapezoidal with apex weakly rounded. Surface minutely and sparsely punctured, matt, with scarce, very short setae.
Elytron yellow with one black median longitudinal stripe ranging from anterior margin to posterior clivus, with its posterior end quite abruptly bent outwards to join lateral margin. More rarely, such stripe simply gradually expanded to reach lateral margin. Suture and posterior margin narrowly black. Epipleuron totally yellow. Lateral light pattern is often more reddish than median one, so that elytron may overall show a more or less evident three-colour pattern. Elytral outline with sides straight and slightly convergent posteriorly, very weakly flattened on disc. Lateral margins narrow, barely visible from above. Elytral surface dull with close punctation, quite irregularly arranged, in particular on basal half. On lighter area bottom of punctures slightly darker than interval surface. Intervals flat. Postscutellar area not raised. Humeral callus prominent, impunctate. Epipleuron smooth, impunctate, strongly convex, barely bent inward.
Pygidium black with two bilobed yellow patches along sides, smooth, matt, covered by sparse minute punctures and rather long, appressed, pale setae.
Ventral parts of thorax totally black or dark brown. Abdominal ventrites yellow laterally. Ventral surface mostly matt, covered with thick, short, regularly distributed setosity and shallow punctures, partly lengthened transversally. Hypomera and mesoepimera polished, bare, almost impunctate. Prosternal process with sides almost straight anteriorly, then slightly divergent and terminated in rounded apical margin. Surface not grooved, flat and wide, covered with sparse, weakly impressed punctures and thick, long, semi-erect setae. Legs brownish, with tibiae and tarsi paler. Posterior femora black to blackish with yellow patches on femora and tibia.
Median depression on fifth abdominal ventrite deeply impressed, subquadrate, shiny, glabrous, impunctate, with posterior margin not notched. Median lobe of aedeagus (Fig. 4c–e) slightly compressed laterally, with apex strongly expanded, well-differentiated from shaft, terminated by small median denticle. In lateral view apex almost straight, ventral outline convex but clearly depressed in middle. Setose depressions deeply impressed, apparent, separated by narrow, short carina, bearing short, curly setae, sitting above all on short, transverse ridge. Such ridge in lateral view looking like triangular raised lamella. Ventral surface delimited from sides by distinct edges.
Endophallus (Fig. 4f) with sclerite I weakly developed and pigmented, basically reduced to membranous fold with upper edge slightly darkened and carrying sharp denticle. Dorsal spicule not detectable. Sclerite II reduced to strongly pigmented, small, short piece with tiny process upward directed. Arch of sclerite III rather wide. Apex of sclerite III short, straight. Branches of sclerite IV equivalent in length to sclerite III in folded-up structure, slender, strongly arched towards ventral direction, with blunt, almost symmetrical, not denticulate apex and surface smooth.
Female. BL = 4.6–5.0 mm, BW = 2.7–3.0 mm, PL = 1.5–1.7 mm, PW = 2.3–2.6 mm. Interocular distance 13.0–14.0 % of BL.
Females differ in a stouter body, wider interocular distance, shorter antennomeres, more slender tarsi. Additionally, the black colour on the pronotum is partly replaced by reddish patches in variable proportions, giving rise to a tri-coloured pattern generally not similarly evident in males.
The fifth abdominal ventrite in females has a large and deep pit. The bottom of the pit is shiny, impunctate, with very short, sparse setae. The vasculum of the spermatheca (Fig. 4g) is moderately pigmented, especially over the basal section, S-shaped with twisted, proximal lobe not swollen. The distal lobe is slender, long with the apex regularly arched and bent downwards. The ampulla is not pigmented, small, short, sitting just at the basal apex of the vasculum. The duct and sperm gland insertions are perceptibly distinct. The duct is uniform in size, short, quite rigid, not coiled but forming a series of turns beside the vasculum, then almost straight. The insertion on the bursa copulatrix is well pronounced, conical, strongly pigmented. In one specimen from Benjamín Aceval (Paraguay), the distal lobe of the vasculum is almost straight with the apex acute and abruptly bent downward.
description: Published as part of Sassi, Davide, 2022, Revision of the Metallactus taeniatellus species group (Coleoptera: Chrysomelidae: Cryptocephalinae), pp. 251-282 in Zootaxa 5125 (3) on pages 261-264, DOI: 10.11646/zootaxa.5125.3.1, http://zenodo.org/record/6443765