Metallactus londonpridei, 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 : 97-99

Metallactus londonpridei sp. nov.

( Figs 16 ; 30 )

Etymology. Dedicated to the excellent beer which inspired some lovely evening meditations during the visits of the author at BMNH.

Type material. HOLOTYPE: ♂, // “Mineiro Goyaz Brésil ” [white label, printed] // “ Metallactus nigrofasciatus Suffr ” [white label, handwritten] // “ Metallactus londonpridei sp. nov. HOLOTYPUS D. Sassi des.” [red label, printed] // ( BMNH). PARATYPES: 1♀, “Mineiro Goyaz Brésil ” [white label, printed] // “F. Monrós Collection 1959” [white label, printed] // ( USNMNH); 1♀, “Mineiro Goyaz Brésil ” [white label, printed] // “ex coll. J. Achard National Museum Prague, Czech Republic ” [white label, printed] // ( NHMP); 1♀, // “Jatahy Etat de Goyaz Brésil ” [white label, printed] // “ex coll. J. Achard National Museum Prague, Czech Republic ” [white label, printed] // “ Metallactus nigrofasciatus Suffr ” [white label, handwritten] // ( NHMP); 2♂ 8♀♀, “Jatahy Etat de Goyaz Ch. Pujol 1895–96 ” [white label, printed] // ( MHNH, DSPC); 1♂ 2♀♀, “Museum Paris Brèsil coll. E. Gonuelle 1915” [green label, printed] // ( MHNH); 1♂, “Matto Grosso Cuijaba” [white label, printed] // ( MHNH). All paratypes provided with additional label: // “ Metallactus londonpridei sp. nov. PARATYPUS D. Sassi des.” [red label, printed] //.

Type locality. Mineiros (Goiás, Brazil) .

Distribution. Brazil.

Diagnosis. A Metallactus of medium–large size. It belongs to the group of species with tronco-conical pronotal outline. Inside this group it is very similar to M. longicornis in having legs completely black and the body outline slightly tapered backwards in male specimens. In the dorsal color pattern and overall appearance, it is also similar to M. kollari . However, males are easily distinguished by the ones of M. longicornis and M. kollari for the morphology of the aedeagus. In addition, in M. kollari the pronotal black design is more extended, with a squared yellow median spot not enlarged towards posterior pronotal margin, which is basically always black. Only in one specimen of M. kollari from Rio de Janeiro (“Ypanema, leg. Natterer”) the yellow spot reaches the posterior rim of the pronotum, so that the black pattern is split into two and the posterior margin is yellow in its median section. Yet, in this case the two black areas are cut medially by a straight line intercepting perpendicularly the posterior margin. Conversely, in M. londonpridei inner rim of the two black areas is sinuous, and therefore the median yellow spot is clearly enlarged towards the posterior margin. In the studied specimens of M. longicornis the pronotal black design always leaves the posterior margin completely yellow. In addition, the antennae in males are much longer and slender. Females of M. longicornis , however, are more difficult to distinguish from the ones of M. londonpridei , and the only character easy to use that seems to work is the chromatic pattern of the pronotum described above. Nevertheless, some differences are evident also in spermathecal duct, which is longer, with looser coils and a longer non-spiralized and more robust distal section in M. londonpridei . However, it is necessary to evaluate the constancy of these differences in female genitalia on a larger number of specimens. Finally, in the latter species, the interocular distance is slightly shorter both in males and in females.

Description of male. Habitus in Fig. 16 a–b (HT). BL = 5.3–5.6 mm, BW = 3.3–3.4 mm, PL = 1.7–1.8 mm, PW = 2.9–3.0 mm. Interocular distance 14.0–14.6% of BL.

Head yellow with vertex, eye canthus and insertion of antennae black. Labrum yellow with brownish upper margin. Surface of frons and clypeus rather closely and regularly punctuated with punctures rather strongly impressed. Vertex feebly and sparsely punctured. Mid-cranial suture fairly impressed and darkened. Head surface with scattered pale setae on vertex, close to ocular rim, eye canthus and sides of clypeus. Antennae normally shaped, with antennomeres 1–5 brownish, the remainders black.

Pronotum yellow with two large stout-hooked black spots reaching backwards the posterior margin but not the anterior one. A little elliptical black spot on median line, just in front of scutellum. Pronotal shape tronco-conical with lateral margins thin, converging forwards and thus not visible at the same time from above. Posterolateral impressions moderately marked, in correspondence of which the posterior margins appear slightly thickened and salient. Pronotal surface moderately shining with scattered, weakly impressed punctuation, sparser on disc.

Scutellum black, dull, quite densely setose, raised, subsquared, very sparsely and minutely punctured.

Elytra yellow with two transverse black stripes not reaching lateral margin and a black rounded spot on apical clivus. First stripe just behind anterior margin, covering humeral calli and tapered towards midline. In one specimen such stripe not reaching the suture, split in two separate stripes. Second stripe often subrectangular but sometimes with some tendency to taper towards suture. Dorsal outline perceptibly tapered backwards, with lateral margins slightly converging towards apex. Surface moderately shiny with punctures small and shallow, in anterior half fairly denser and more impressed than towards the back and partly arranged in almost regular rows disappearing in elytral apex. Intervals smooth.

Pygidium black, densely setose and quite coarsely punctured.

Inferior parts, with the exception of outer yellow part of hypomera, entirely black and covered by pale, dense setae. Surface of prosternal process covered by long and whitish setae, longitudinally sulcated with apex triangular. Apex of prosternal process in holotype with a blunt, slightly raised brownish denticle on the top, such denticle barely visible in some paratypes. Legs entirely black.

Fifth abdominal ventrite with a rather deep, bare, hemispherical and lustrous depression and posterior margin fairly notched. Median lobe of aedeagus ( Fig. 16 c–e) with elongated, quite blunt apex, barely separated from aedeagal tube, almost straight in lateral view. Hairy dents very shallow, indistinct, rather lengthened, sparsely setose. Aedeagal ventral surface not swollen in lateral view, so the profile is rather straight, perceptibly raised only close to basal foramen.

Endophallus ( Fig. 16 f–g) with sclerite I fairly developed but scarcely pigmented, only denticle darkened. Dorsal spicule reduced to simple brownish patch, connected to sclerite I by a ribbon-like, darkened structure. Sclerite II rather short, distinctly bent at base. Arch of sclerite III slender, raised. Apex of sclerite III straight and pointed, fairly expanded on its proximal half, so that the sclerite resembles the head of a grebe. Branches of sclerite IV starkly shorter than sclerite III in the folded up structure, almost straight, stout, with apex subtruncate and surface fairly rugose.

Female. BL = 6.6–7.1 mm, BW = 4.0– 4.3 mm, PL = 2.1 mm, PW = 3.5–3.7 mm. Interocular distance 17.4– 18.3% of BL. In the examined specimens black pattern more extended on frons and clypeus than in holotype, sometimes yellow can be reduced to a U-shaped spot between eyes. Black transversal elytral pattern often deeper than in males.

Fifth abdominal ventrite in females with a rather impressed hemispherical pit and distal margin slightly notched in the middle. Spermatheca ( Fig. 16h ) quite short, not pigmented with apical and basal branch of vasculum subequal in length. Basal branch feebly swollen at base, with dorsally placed insertions of gland and duct. Duct very long, first part slender, last trait perceptibly more robust, with coils characteristically loose and even looser in distal half, very distal section not coiled. Insertion on bursa copulatrix slightly swollen, almost straight. Rectal apparatus ( Fig. 16 k–m) with dorsal sclerites laterally not projected beyond rectus, narrow, abruptly tapered towards median line, with apodemes quite narrow, hyaline, bent upwards and leaning against rectum, thus barely visible from above. Dorsal chitinous area caudal to dorsal sclerites well developed, deep, with median longitudinal fold well pronounced and partly pigmented. Ventral sclerite large, ellipsoidal, tapered on sides, less pigmented in middle, with rounded apodemes, crenulate and fairly wider than rectum.

Remarks. There are no reasonable doubts that M. londonpridei and M. longicornis actually constitute two distinct taxa, given the clear difference in the morphology of the aedeagus. However, despite the description given above in the differential diagnosis, females of these two species are problematic to be identified for certain. Without the examen of spermathecal duct, the only female diagnostic characters are in fact basically chromatic, and it is difficult to fully evaluate their actual intraspecific variability, given the little material available. On the basis of the adopted criteria, however, M. londonpridei seems to be limited to the State of Goiás, while the putative M. longicornis area would extend from that same territory both to the North West (state of Mato Grosso), and to Southeast (states of São Paulo and Minas Gerais). In essence, M. londonpridei would occupy a small area within a wider M. longicornis territory, and in this sector the two species might be cohabiting.

Figures

FIGURES 15–16. M. longicornis (15), M. londonpridei (16). 15a–b/a1: habitus; 15c–e: median lobe of aedeagus in ventral (c), dorsal (d) and lateral (e) view [1.2 mm]; 15f: sclerites II–III–IV of endophallus [0.6 mm]; 15g: sclerite I and dorsal spicule of endophallus [0.6 mm]; 15h: spermatheca [0.9 mm]; 15k–m: rectal apparatus in dorsal (k) and ventral (m) view [1.4 mm]; 15n: antenna [2.2 mm]. 16a–b: habitus; 16c–e: median lobe of aedeagus in ventral (c), dorsal (d) and lateral (e) view [0.9 mm]; 16f: sclerites II–III–IV of endophallus [0.6 mm]; 16g: sclerite I and dorsal spicule of endophallus [0.8 mm]; 16h: spermatheca [0.9 mm]; 16k–m: rectal apparatus in dorsal (k) and ventral (m) view [1.3 mm]. 15a–b: holotype; 15a1: paratype from Cuyaba, Mato Grosso, Brazil); 16a–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.