Metallactus rileyi, Sassi, 2018

Sassi, Davide, 2018, Revision of the Metallactus kollari species-group with a new diagnosis of the genus (Coleoptera: Chrysomelidae: Cryptocephalinae), Zootaxa 4413 (1), pp. 57-110 : 91-94

Metallactus rileyi sp. nov.

( Figs 2 ; 13 ; 35 )

Etymology. The species is dedicated to Edward G. Riley, specialist in Chrysomelidae , who supplied me with a huge amount of interesting Neotropical material and was the collector of most of the specimens of this new species.

Type material. The typification has been made as follows. HOLOTYPE: ♂, glued, aedeagus extracted and glued, together with the abdomen, on the same label bearing the specimen, // “Parag: Pres. Hayes 42 Km NW Benjamín Aceval: Jan. 31, 83: E.G. Riley” [white label, printed] // “ Metallactus rileyi sp. nov. HOLOTYPUS D. Sassi des.” [red label, printed] // ( TAMU). PARATYPES: 23♂ 23♀♀, same data of the holotype; 1♀, “ Paraguay Puerto San Pablo I.1937 Lapchinos cy” [white label, printed] // “Museo civico di Genova” [grey label, printed] //; 1♂ 1♀, “ Argentina Entre Rios Liebig XII-87 ” [white label, printed] //; 1♀, “ Argentina Entre Rios X.1993 ” //; 1♀, “ Argentina Entre Rios Liebig XII-90 ” [white label, printed] //; 7♀♀, “ Argentina Entre Rios XII 93 Pena” [white label, printed] //; 1♀, “ Argentina Entre Rios Villaguay 5 Jan. 1983 V. Krischik Liebig XII-87 ” [white label, handwritten] //; 1♂, “ Argentina For., 34 Km NE Formosa 27-I-1989 C.W. & L.W. O'Brien & G.J. Wibmer” [white label, printed] //; 1♀, “ Argentina For. 22 KM W Clorinda I-26-1989 C. & L. O'Brien & G. Wibmer ” [white label, printed] //; 1♀, “ Argentina Formosa Capital XI.950 Daguerre ” [white label, handwritten] //; 1♀, “ Argentina Formosa La Lomitas XI.950 Daguerre ” [white label, handwritten] //; 3♂ 2♀♀, “ Formosa Gran Guardia XII.951 Coll. J Föester ” [white label, handwritten] // F. Monrós Collection 1959 [white label, printed] //; 4♀♀,”R.A. Formosa Gran Guardia XII.951 Coll. J Föester ” [white label, handwritten]// “ F. Monrós collection 1959” [white label, printed]//; 1♂, “T. N. Formosa R. A. XI.1953 Loc. Gran Guardia” [white label, printed] //; 1♂, “Hungarian Soil-Zool.Exp. Argentina Prov. Chaco Resistencia 23.XII.1965 ” [white label, printed] // “Nr. P-B.313 Mahunka ” [white label, printed] //; 1♀, “ Argentina prov. Chaco 2.IX.1949 ” [white label, handwritten] // “ Colonia Benitez leg. M. Aczél ” [white label, handwritten]; 3♂, “ Argentina Santa Fè Rt 9 Rio Carcaraña 9 dec. 1991 ” [white label, printed] // “sweeping Baccharis spartioides P.E. Boldt & G. Logarzo collectors” [white label, printed]; 1♂ 1♀, “ Santa Fe dep. Gorray III.950 Daguerre ” [white label, handwritten] // “ Argentina 1968 Coll. J Daguerre ” [white label, printed]; 1♀, “ Argentina E.R. 22 Km E Basavilbaso Hwy. 39 14-I-1989 C. & L. O'Brien & G. Wibmer ” [white label, printed] //; 1♂, “ Argentina E.R. Hwy. 6 nr. Raices I-14-1989 CW. & L. O'Brien & G. Wibmer ” [white label, printed] //; 4♂ 2♀♀, “ Uruguay Paysandú Puerto Pepe Ají 21-25 January 1970 G.J. Wibmer ” [white label, printed] //; 1♀, “ Uruguay Colonia Ruta 21 Piedra de los Indios 9-XI-1992 G.J. Wibmer ” [white label, printed] //; 1♂ 1♀, “ Uruguay Colonia Piedra de los Indios ca. R.21 Km 184.5 17-XII-1999 G.J & A.J. Wibmer ” [white label, printed] //; 1♂, “ Uruguay Colonia San Pedro Ruta 21 ca. Km 186.5 10-II-2014 G.J. Wibmer ” [white label, printed] //; 1♀, “ Brasil Virm.” [blue label, handwritten] // “ Syntypus Metallactus albipes Suffrian,1866 labelled by MNHUB 2013 ” [Red label, printed]//. All paratype s are labelled: // “ Metallactus rileyi sp. nov. PARATYPUS D. Sassi des.” [red label, printed] // ( TAMU, ERPC, MNHUB, USNMNH, BYU, HNHMB, DSPC, MSNM) .

Type locality. Benjamín Aceval (Departamento de Presidente Hayes, Paraguay) .

Distribution. Argentina, Brazil, Paraguay, Uruguay.

Diagnosis. A Metallactus of medium size. It belongs to a subgroup of species with tronco-conical pronotal outline and legs at least partly yellow. This subgroup comprises also M. patagonicus , M. pollens , M. dodecastictus and M. bezoar . Among these species M. riley is the one with the most evident tendency for elytral black spots to coalesce. In the other species the most frequent pattern is made up by fairly distinct pairs of subrounded spots. The most similar is M. pollens , but the new species is well distinguished by the aedeagal apex ended by a blunt denticle, fairly separated by the tube by means of its concave sides. Other distinctive characters are: smaller size, pronotum somewhat more lengthened, abdominal sternites yellow or slightly darkened in the median region, median depression on male fifth abdominal sternite slightly more impressed. Moreover, the black pronotal pattern seems constant and distinctive: two angulate oblique spots, generally reaching the anterior margin of pronotum, separated by a yellow median band. Besides, a slightly elongated small black spot is placed in front of the scutellum. However, the small black spot can be fused to the basis of the larger lateral ones. In M. pollens the pronotal black pattern is less oblique, not reaching the anterior margin of pronotum. In addition, in male specimens of M. pollens antennomeres are considerably longer. Lastly, the comparison with the latter species also shows interesting differences in the ocular shape. In M. rileyi the interocular distance is shorter, the eyes are fairly more bulging both in males and in females, the upper ocular lobe is larger, the lower one is more protruding laterally and it tends to partially hide the pronotal margin in frontal view.

Description of male. Habitus in Fig. 13 a–b (HT). BL = 5.0– 5.4 mm, BW = 2.9–3.0 mm, PL = 1.7–1.8 mm, PW = 2.5 mm. Interocular distance 8.4–10.6% of BL.

Head yellow with vertex, a longitudinal median line following mid-cranial suture and antennal insertions black. Labrum yellow to brownish. Surface flat, mid-cranial suture generally apparent, deep but sometimes blurred, almost obliterated. Punctures moderately impressed, scattered, denser along the inner ocular rim. Punctures on vertex smaller and shallower. Setosity reduced to few scattered setae on vertex, close to inner eye rims, lower part of clypeus and labrum. Antennae ( Fig. 13m ) normally shaped with antennomeres 1–5 brownish and the remainders black.

Pronotum yellow with two large bilobate black spots obliquely arranged, not reaching lateral margins. A little elliptical brownish spot on median line, just in front of scutellum. Pronotal shape slightly tronco-conical with lateral margins thin, moderately converging forwards, scarcely visible from above and posterolateral impressions faintly impressed. Surface moderately shining with scattered, weakly impressed punctuation, sparser on disc.

Scutellum black, dull, sparsely setose, raised, subsquared, with truncated apex, scarcely and minutely punctured.

Elytra yellow with a black pattern shaped as follows. Two transverse sinuous black stripes, the anterior one covering humeral calli and lateral margins but not reaching suture and leaving anterior margin almost completely free, this anterior band often split in two separate spots. The posterior stripe extended to lateral margin but not expanding to suture, sometimes split in two separate spots as well. A pair of black slightly lengthened spots on apical clivus, the inner one larger. Suture, lateral margin narrowly black. Anterior trait of epipleura yellow with the exception of lower rim which is narrowly black or brownish. Parallel-sided, almost regularly convex on disc, with postscutellar area faintly raised and humeral calli fairly bulging. Surface moderately shiny with small and shallow punctures partly arranged in almost regular rows disappearing on elytral apex. Intervals smooth.

Pygidium yellow, densely setose, sparsely and shallowly punctured, covered by pale, dense setae.

Inferior parts of thorax black with prosternal process, outer part of hypomera and midline of mesosternum yellow. Abdominal surface entirely yellow to largely brownish on midline. Surface of inferior parts covered by quite dense, whitish setae and quite evenly punctured. Surface of prosternal process covered by long curly and whitish setae, longitudinally sulcated, with apex rounded and slightly raised. Legs yellow, tarsi, apex of tibiae and some patches on fore femora black.

Fifth abdominal ventrite with a shallow bare triangular depression and posterior margin distinctly notched. Median lobe of aedeagus ( Fig. 13 c–e) yellow, subcylindrical. Aedeagal apex markedly distinct from aedeagal tube, shortly triangular with sides fairly curved inwards and almost straight in lateral view. Hairy dents apparent, distinctly impressed, sparsely setose. Aedeagal ventral surface not swollen in lateral view, so the profile is rather straight and relatively squat.

Endophallus ( Fig. 13 f–g) with sclerite I weakly sclerotized, not pigmented, large, with denticle straight, thin, blunt. Dorsal spicule hugely developed, sinuose, with a swollen, blunt, sac-like tip. Sclerite II slender, straight. Sclerite III rather oblique, with arch scarcely raised, gradually narrowed on apex. Branches of sclerite IV longer than sclerite III in the folded up structure, smooth, not sculpturate, evenly thickened and slightly sinuate, with an asymmetrical pointed apex perceptibly bent.

Female. BL = 6.1–6.5 mm, BW = 3.4–3.7 mm, PL = 2.0– 2.1 mm, PW = 2.9–3.2 mm. Interocular distance 14.0% of BL.

Fifth abdominal ventrite in females with a rather deep hemispherical pit and distal margin straight, not notched in the middle. Spermatheca ( Fig. 13h ) quite short, rather pigmented on its median trait. Apical branch of vasculum shorter and slenderer than the basal one, with apex bluntly tapered, straight to fairly bent downwards. Basal branch straight, uniform in size. Insertions of gland and duct faintly shifted dorsally. Duct quite short, slender, strictly coiled on its proximal and medial trait. Distal part of duct barely coiled with insertion on bursa copulatrix swollen, darkened, sinuous. Rectal apparatus ( Fig. 13 k–m) with dorsal sclerites laterally not projected beyond rectus, narrow, gradually tapered towards median line, with apodemes quite large, hyaline, bent upwards and leaning against rectum, thus barely visible from above. Ventral sclerite large, somewhat elliptical, moderately tapered on sides, less pigmented in middle, with large rounded apodemes wider than rectum and crenulate on rim.

Available biological data. Biology is unknown, some label data of specimens coming from Santa Fè

( Argentina) point to Baccharis spartioides (Hook. & Arn. ex DC.) J. Remy as host plant.

Figures

FIGURES 1–2. median lobe of aedeagus with everted endophallus. M. albipes (1), M. rileyi (2). a: dorsal view; b: lateral view. scI–IV: sclerites I–IV of endophallus; ds: dorsal spicule. Length of scale segment: 1.6 mm.

FIGURES 13–14. M. rileyi (13), M. bellatrix (14). 13a–b: habitus; 13c–e: median lobe of aedeagus in ventral (c), dorsal (d) and lateral (e) view [1.0 mm]; 13f: sclerites II–III–IV of endophallus [0.6 mm]; 13g: sclerite I and dorsal spicule of endophallus [0.9 mm]; 13h: spermatheca [0.8 mm]; 13k–m: rectal apparatus in dorsal (k) and ventral (m) view [0.9 mm]; 13n: antenna [1.5 mm]. 14a–b: habitus; 14h: spermatheca [0.7 mm]; 14k–m: rectal apparatus in dorsal (k) and ventral (m) view [0.9 mm]. 13a–b: holotype; 14a–b: holotype. Square brackets: length of scale segment.

FIGURES 29–36. Distribution maps for Metallactus kollari species-group. M. languidus (29); M. londonpridei (30); M. longicornis (31); M. patagonicus (32); M. pollens (33); M. regalini (34); M. rileyi (35); M. spilotus (36). Grey squares: localities reported in a generic way.