Metallactus dicaprioi, Sassi, 2019

Sassi, Davide, 2019, Revision of the Metallactus hamifer species-group (Coleoptera: Chrysomelidae: Cryptocephalinae), Zootaxa 4657 (2), pp. 201-245 : 221-223

Metallactus dicaprioi sp. nov.

( Figs 8 ; 25 )

Type. HOLOTYPE: ♂, glued, aedeagus and detached abdomen glued on a separate card // “ Argentina: Estancia Don Roberto, Lavaisse , San Luis. 12. Oct. 1942.” [white label, printed] // “ Pres. by W. Wittmer B. M. 1945-33.” [white label, handwritten] // “ Metallactus dicaprioi sp. nov . HOLOTYPUS D. Sassi des.” [red label, printed] // ( BMNH). PARATYPES: 5♂ 1♀, same data of the holotype // “ Metallactus dicaprioi sp. nov . PARATYPUS D. Sassi des.” [red label, printed] // ( BMNH, DSPC) .

Type locality. Lavaisse (San Luis, Argentina).

Etymology. The species is named after Leonardo Di Caprio, a popular American actor, also known for his constant commitment to the preservation and conservation of biodiversity.

Distribution. Argentina.

Diagnosis. A Metallactus of small size. It mostly resembles the “typical” chromatic form of M. hamifer ( Fig. 9 a-b), which differs in stronger elytral and pronotal punctation, in generally more transverse elytral spots, in light color on forehead limited to lower part of vertex, in the shape of median lobe. Compared to this last species, M. dicaprioi differs in some feeble traits of the endophallus sclerites: the anterior spicules are proportionally smaller and the denticle on sclerite I is more developed. Besides, the ventral profile of the median lobe of the aedeagus is basically straight (slightly convex in M. hamifer ).

M. luniger is somehow similar in dorsal color pattern, the pronotal one in particular, but it is well distinguished by its stockier outline and the perceptibly larger pronotal longitudinal light pattern. In almost all the examined specimens of M. dicaprioi the prosternal process is yellow whereas it is totally black in the related species.

Description of male. Habitus in Fig. 8 a–b (HT). BL = 3.7–4.3 mm, BW = 2.2–2.5 mm, PL = 1.4–1.6 mm, PW = 2.0– 2.3 mm. Interocular distance 10.8–14.0% of BL.

In holotype head black with two sickle-shaped yellow spots, slightly raised, close to the upper part of ocular rims, clypeal surface yellow as well. In some paratypes yellow pattern extended over whole frontoclypeal surface. Labrum yellowish with upper part black. Vertex quite dull, bare, with few, scattered, shallow punctures. Frontoclypeal area with quite coarse punctation and sparse, pale setae, rather long and curly above all close to ocular rims. Mid-cranial suture short, well impressed in particular between sickle-shaped yellow spots. First five antennomeres yellowish, sublucid, the subsequent ones totally darkened, dull, more flattened and more diffusedly setose.

Pronotum black with lateral margin and outer part of anterior and posterior margins covered with a single Cshaped yellow spot; a median linear yellow stripe, slightly broadened on posterior end, extended from anterior to posterior margin just in front to scutellum. Pronotal shape quite long-elliptical with lateral margins thin, barely visible from above, regularly curved with maximum width slightly behind the middle. Posterolateral impressions obliterated. Surface moderately lustrous with scattered, weakly impressed punctation, sparser and shallower on disc.

Scutellum totally black, dull, distinctly raised, finely setose and minutely punctured. Apex sharply truncated in a straight line.

Elytral surface black with four yellow spots lined up along suture. First spot, oblique, beside scutellum; second one, elliptical, at middle; third one, transverse, on apical clivus; fourth one, something smaller, elliptical, at apex. Anterior third of lateral margin yellow as well with yellow patch extended to epipleuron and salient along anterior margin up to humeral callus. Elytral outline parallel-sided and very weakly flattened on disc. Postscutellar area slightly raised. Humeral callus prominent, impunctate. Surface moderately shiny with fine punctures arranged in almost regular rows, punctures rather confused only on anterior inner part of disc. Intervals flat.

Pygidium black with two yellow spots on sides, smooth, covered with dense shallow punctures and rather long, whitish setae.

Inferior parts of thorax black, only hypomera bordered with yellow on outer margin. Prosternal process yellowish in all but one specimen. Hypomera rugosely punctured, almost bare. Mesoepimera and mesoepisterna with scarce shallow punctures and scattered setae. Metaepisterna and metasternum with quite coarse, shallow punctation and sparse setae. Prosternal process coarsely punctured with long setae and slightly raised, blunt triangular apex. Abdominal ventrites black with yellow border very finely and sparsely punctured, with relatively long, sparse setae. Legs totally black.

Median depression on fifth abdominal ventrite very small, shallow, opaque, barely distinguishable, limited to very distal part of ventrite. Notch on posterior margin of fifth abdominal ventrite shallow, but clear-cut, apparent. Median lobe of aedeagus ( Fig. 8 c–e) with tube slightly constricted on sides in ventral view so that median line looks carinate to some extent, with apex short, triangular, blunt, scarcely separated from the rest of aedeagus. In lateral view apex faintly bent ventrally at its very top. Hairy dents faintly limited, barely perceivable, bearing rather long, dense and curly setae. Aedeagal ventral surface not swollen in lateral view, devoid of particular structures. Endophallus ( Fig. 8 g–h) with sclerite I well developed and pigmented, denticle apparent, large, blunt, pointing forwards and not sticking out laterally. Dorsal spicule greatly developed, straight, raised. Sclerite II rather slender, bent at about middle and gradually tapered towards apex. Arch of sclerite III low, slender, gradually blending in a slender, regularly tapered apex, so that barely distinguishable from it. Apex of sclerite III not expanded on its proximal section. Branches of sclerite IV equivalent in length to sclerite III in the folded-up structure with blunt, slightly asymmetrical apex and surface distinctly rugose.

In a single male specimen second elytral yellow spot is missing and legs are lighter with base of femora mostly yellow.

Female. BL = 4.8 mm, BW = 2.8 mm, PL = 1.5 mm, PW = 2.5 mm. Interocular distance 18.8% of BL.

Fifth abdominal ventrite in females with quite large, well pronounced, weakly transverse pit. Vasculum of spermatheca ( Fig. 8k ) slender, scarcely pigmented, with sinuose proximal branch, long distal branch and moderately pointed apex feebly bent downwards. Ampulla not pigmented, vaguely shifted on dorsal side of vasculum. Duct and sperm gland insertions perceptibly distinct. Duct uniform in size, slender, coiled, coils rather thick and quite regularly arranged. Distal portion of duct and insertion on bursa copulatrix damaged so as not detectable in the single available female.

Figures

FIGURE 9. M. hamifer. 9a–e: habitus (a–b “typical” colour pattern, c–e: chromatic variations); 9f: sclerites of endophallus [0.5 mm]; 9g–h: median lobe of aedeagus in ventral (c), dorsal (d) and lateral (e) view [0.6 mm]; 9m: spermatheca [0.9 mm]; 9n: antenna [2.2 mm]. 9a–b: lectotype; 9c–d: Argentina, Entre Rios; 9e: Argentina, Cordoba, Calamuchita, Salsacate. scI–IV: sclerites I–IV of endophallus; ds: dorsal spicule. Square brackets: length of scale segment.

FIGURES 7–8. M. crassicollis (7), M. dicaprioi (8). 7a–b: habitus; 7c–e: median lobe of aedeagus in ventral (c), dorsal (d) and lateral (e) view [0.7 mm]; 7f: antenna [2.1 mm]; 7g: sclerites of endophallus [0.2 mm]. 8a–b: habitus; 8c–e: median lobe of aedeagus in ventral (c), dorsal (d) and lateral (e) view [0.7 mm]; 8f: antenna [2.1 mm]; 8g: sclerites I–II and dorsal spicule of endophallus [0.7 mm]; 8h: sclerites III–IV of endophallus [0.5 mm]; 8k: spermatheca [0.5 mm]. 7a–b: paralectotype; 8a–b: holotype. scI–IV: sclerites I–IV of endophallus; ds: dorsal spicule. Square brackets: length of scale segment.

FIGURES 18–26. Distribution maps for Metallactus hamifer species-group. M. abditus (18); M. agonista (19); M. albivittis (20); M. albopictus (21); M. bivitticollis (22); M. chamorroi (23); M. crassicollis (24); M. dicaprioi (25); M. hamifer (26). Grey squares: localities reported in a generic way.