Metallactus regalini, 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 : 99-100

Metallactus regalini sp. nov.

( Figs 17 ; 34 )

Etymology. The species is dedicated to my friend and colleague Renato Regalin, valuable specialist in Chrysomelidae Clytrini , who passed away after a stouthearted struggle with cancer in the early part of 2016.

Type material. HOLOTYPE: ♂, // “ Brasil Parana Mallo do Hamer R. Longo leg.” [white label, handwritten] // “ F. Monrós Collection 1959” [white label, printed] // “ Metallactus regalini sp. nov . HOLOTYPUS D. Sassi des.” [red label, printed] // ( USNMNH). The holotype is the only specimen known so far .

Type locality. Mallo do Hamer (Parana, Brazil) .

Distribution. Brazil.

Diagnosis. A Metallactus of small size. It is quite similar to M. bezoar in size and dorsal colour pattern, but it differs in having legs completely black and head yellow colour pattern formed by a small triangular spot on lower part of vertex (in M. bezoar femora and basal half of tibiae are yellow and head yellow pattern is a x-shaped spot extended on lower part of frons and clypeus). Besides, pronotal outline in M. regalini is more transverse and elliptical (slightly tronco-conical in M. bezoar ). Aedeagal shape is also different comparing the two species. M. londonpridei is also similar in elytral and ventral patterns, but it differs in larger size, different pronotal coloration and different aedeagal shape. Pronotal outline is also different in M. londonpridei , being slightly subconical and not elliptical, with almost straight lateral margins.

Description of male. Habitus in Fig. 17 a–b (HT). BL = 4.5 mm, BW = 2.7 mm, PL = 1.6 mm, PW = 2.4 mm. Interocular distance 14.4% of BL.

Head black, with a triangular yellow spot on lower part of vertex. Labrum blackish. Head surface with sparse pale setae. Mid-cranial suture short, blurred. Vertex almost impunctate. Frons and clypeus rather coarsely punctate in particular close to ocular rims and across midline. Antennae almost completely black, only first and second antennomeres partly brownish.

Pronotum yellow with a large, rectangular black plague not reaching margins. Pronotal shape sub-elliptical with lateral margins thin, regularly curved, barely visible from above. Posterolateral impressions faint, almost indistinct. Surface lustrous with scattered, fairly impressed punctation, slightly sparser and shallower on disc.

Scutellum completely black, distinctly raised, sub-squared with truncated apex, almost bald and impunctate with tiny and sparse micropuncturation.

Elytra yellow with black pattern consisting of two large transverse bands and a pair of small rounded spots on apex. First transversal band including basal margin and not reaching lateral ones. Second transversal band, just behind half of elytra, extending from suture up to last interval but not reaching the lateral margins. Surface rather lustrous with punctation moderately impressed, denser on anterior half of disc, partly arranged in almost regular striae, fairly reduced and shallower on apical clivus. Intervals flat.

Pygidium yellow with a transverse black stripe on proximal margin and an elliptical black one on apex, with surface smooth, covered by sparse shallow punctures and whitish setae. Two little rounded pits close to each lateral margin of pygidium, roughly at half of length.

Inferior parts of thorax completely black, only hypomera partly yellow on outer half. Abdominal ventrites black on midline, extensively yellow on sides, regularly and shallowly punctate and setose. Prothorax (prosternal process and hypomera) coarsely punctate; meso and metathorax coarsely punctate on sides, covered by whitish setae above all on midline. Prosternal process normally shaped, longitudinally grooved, apex blunt, surface covered with very long dense whitish setae. Legs black.

Fifth abdominal ventrite with a median, brownish, fairly impressed depression, smooth, glabrous, impunctate and posterior margin rather deeply notched. Median lobe of aedeagus ( Fig. 17 c–e) with sides slightly concave in ventral view, with apex wide, elongated, blunt, almost straight in lateral view. Hairy dents shallow, very poorly delimited, bearing quite long, straight and fairly close setae. Ventral profile weakly swollen in lateral view.

Endophallus ( Fig. 17 f–g) with sclerite I strongly developed and pigmented, denticle apparent, bent upwards and perceptibly sticking out laterally. Dorsal spicule strongly reduced, thorn-like. Sclerite II well developed, distinctly bent at base and gradually tapered towards apex. Arch of sclerite III slender, raised. Apex of sclerite III straight and pointed, fairly expanded on its proximal half, so that the sclerite looks like the head of a grebe. Branches of sclerite IV definitely shorter than sclerite III in the folded up structure, distinctly arched, with blunt, almost symmetrical apex and surface fairly rugose.

Female unknown.

Figures

FIGURES 17–18. M. regalini (17), M. bezoar (18). 17a–b: habitus; 17c–e: median lobe of aedeagus in ventral (c), dorsal (d) and lateral (e) view [0.8 mm]; 17f: sclerites II–III–IV of endophallus [0.5 mm]; 17g: sclerite I and dorsal spicule of endophallus [0.4 mm]. 18a–b: habitus; 18c–e: median lobe of aedeagus in ventral (c), dorsal (d) and lateral (e) view [0.8 mm]; 18f: sclerites II–III–IV of endophallus [0.6 mm]; 18g: sclerite I and dorsal spicule of endophallus [0.5 mm]. 17a–b: holotype; 18a–b: holotype. hd: hairy dent: scI–IV: sclerites I–IV of endophallus; ds: dorsal spicule. 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.