Metallactus chamorroi, Sassi, 2019

Sassi, Davide, 2019, Revision of the Metallactus hamifer species-group (Coleoptera: Chrysomelidae: Cryptocephalinae), Zootaxa 4657 (2), pp. 201-245 : 217-219

Metallactus chamorroi sp. nov.

( Figs 6 ; 23 )

Types. HOLOTYPE: ♂, glued, aedeagus on the same card, detached abdomen and sclerites of endophallus on a sepa- rate card // “ Caraça (Minas Geraez) Brésil E. Gounelle 1.2.1885 ” [white label, printed] // “ Muséum Paris 1915 E. Gounelle ” [green label, printed] // “ Metallactus chamorroi sp. nov . HOLOTYPUS D. Sassi des.” [red label, printed] // ( MNHN). PARATYPES: 1♀, same data of holotype ( DSPC); 1♀ // “Brésil Caraça P. Germain 2° Semestre 1884” [green label, printed] // ( MNHN); 1♀ // [rounded green label, unwritten] // “ Brasil ” [white label, handwritten] // ( ZSM); 1♀ // “ Paraguay Dep. Conception” [white label, printed] // “5 Km N of Tacuati III.1989 ” [white label, printed] // “87” [white label, printed] // “IDe_119” [white label, printed] // ( DSPC). All paratypes provided with additional label: // “ Metallactus chamorroi sp. nov . PARATYPUS D. Sassi des.” [red label, printed].

Etymology. The species is dedicated to M. Lourdes Chamorro-Lacayo, specialist in Chrysomelidae who, by means of some inspiring papers, paved the way for the revision of the lengthily neglected Neotropical Pachybrachina .

Type locality. Serra do Caraça ( Brazil, Minas Gerais).

Distribution. Brazil, Paraguay.

Diagnosis. A Metallactus of medium size. It belongs to the subgroup characterized by longitudinal elytral design of alternately lighter and darker stripes. The dark dorsal pattern is generally brownish or reddish, never decidedly black as in M. viator , M. bivitticollis , M. pollinctor and M. hamifer . M. praetorius is the most similar in color pattern, but it differs in broader interocular distance, in the shallower punctation of head and, above all, in the aedeagal shape. M. agonista differs in pronotal color pattern more diffusedly reddish with some black spots and, again, in the aedeagal shape. M. tarsalis is quite similar, but in the studied specimens the elytral dark pattern is missing, the pronotal punctation is weaker and almost obliterated along the middle part of disc. Besides, the aedeagal shape is quite different as well. M. sekerkai is also similar, but elytral pattern consists of a single large reddish longitudinal stripe instead of two. Besides, aedeagal median lobe and endophallus are very different in the latter species.

Description of male. Habitus in Fig. 6 a–b (HT). BL = 5.2 mm, BW = 2.9 mm, PL = 1.7 mm, PW = 2.6 mm. Interocular distance 11.5% of BL.

Head reddish brown with yellow border along inner and upper rim of eyes. Lower part of clypeus yellow as well. Antennal insertion and mid-cranial suture blackish. Labrum off-white. Vertex scarcely shiny, bare. Frontoclypeal area with sparse pale setae. Head surface covered with sparse, quite coarse punctures. Ocular lines well impressed and roughly punctured, perceptible up to antennal insertions. Mid-cranial suture quite long, marked by well distinguishable impression extended to lower part of frons. Surface surrounding mid-cranial suture slightly swollen. First five antennomeres reddish, sublucid, the subsequent ones totally darkened, dull, more flattened and more diffusedly setose.

Pronotum yellow with two large longitudinal stripes, extending from anterior margin to posterior one, progressively widened backwards. Those stripes are black with posterior section red along outer side. Pronotal shape elliptical, rather transverse. Lateral margins thin, almost not visible from above, regularly curved with maximum width just behind half length. Posterolateral impressions obliterated so that posterior margin not swollen behind it. Surface regularly convex, moderately shiny with rather coarse, close punctation clearly visible also across central part of disc.

Scutellum ochraceous, rather shiny, distinctly raised, minutely punctured. Apex truncated in a straight line.

Elytron surface yellow with two longitudinal reddish brown to blackish stripes extending from anterior margin to apical clivus. Inner stripe in continuity with the pronotal one, slightly tapered posteriorly. Outer stripe slender, running over humerous, scarcely tapered towards apex. Suture narrowly black. Outline sightly convergent towards apex and very weakly flattened on disc. Postscutellar area not raised. Humeral callus scarcely prominent, impunctate. Surface moderately shiny with well impressed, rather close punctures irregularly distributed across anterior inner part of disc, laterally arranged in irregular rows. Intervals flat.

Pygidium yellow, smooth, rather shiny, covered with sparse well impressed punctures and whitish setae.

Inferior parts of thorax blackish. Outer part of hypomera, apex of prosternal process, mesoepimera, mesoepisterna, outer part of metasternum and metaepisterna yellowish. Hypomera, mesoepimera and mesoepisterna almost bare with scarce shallow punctures. Metaepisterna and metasternum with quite coarse punctation and sparse setae. Prosternal process coarsely punctured with long setae and slightly raised short triangular apex. Abdominal ventrites mostly yellow with infuscate or dark patches on inner sections of surface, sparsely punctured, with long straight setae. Legs yellow with tarsi infuscate.

Median depression on fifth abdominal ventrite shallow and large, bare, with shiny bottom. Posterior margin of fifth abdominal ventrite weakly notched. Median lobe of aedeagus ( Fig. 6 c–e) with sides slightly divergent towards apex in ventral view, so that apical section wider than base to some degree. Apex delimited by a blunt denticle, in lateral view faintly bent ventrally. Hairy dents rather lengthened, bearing rather short, sparse setae, internally delimited by two narrow, shallow impressions. Aedeagal ventral surface barely swollen in lateral view. Endophallus ( Fig. 6g ) with sclerite I strongly developed and pigmented, denticle apparent, robust, pointing upwards and not sticking out laterally. Dorsal spicule missing. Sclerite II well developed, squat, gradually bent at base, slightly tapered towards apex. Arch of sclerite III slender, low. Apex of sclerite III straight and pointed, gradually tapered, not expanded on its proximal part. Branches of sclerite IV longer than sclerite III in the folded-up structure, sinuate, with blunt apex very finely microdenticulate on its upper rim, and surface distinctly rugose.

Female. BL = 6.0– 6.2 mm, BW = 3.4–3.6 mm, PL = 1.9–2.0 mm, PW = 3.1–3.3 mm. Interocular distance 15.0–17.7% of BL.

Fifth abdominal ventrite in females with quite large and rather deep pit, bare, opaque, with sparse, minute punctures on bottom. Vasculum of spermatheca ( Fig. 6h ) quite slender, scarcely pigmented with straight, long proximal branch slightly swollen at base, almost equally long distal branch slightly swollen at middle and then abruptly tapered in a bent, sharpened apex. Ampulla distinctly pigmented, slightly shifted on dorsal side of vasculum. Duct insertion and sperm gland insertion distinct. Duct uniform in size, coiled, coils rather thick and quite regularly arranged. Distal not coiled portion of duct rather short, winding. Insertion on bursa copulatrix slender, not swollen nor pigmented.

Remarks. In the only male available the dorsal spicules of endophallus are missing and that seems not to be an artifact. However, further material would be welcome to clarify the issue. The female from Paraguay looks somewhat different from the remaining ones as regard the chromatic pattern: dark pronotal stripes are totally reddish and more obliquely arranged, besides, elytral stripes are completely black. Conversely, other characters, in particular the punctation of the head, conform quite well with the pattern of the present species. For those reasons, this specimen has been attributed to M. chamorroi with some misgivings.

Figures

FIGURES 5–6. M. bivitticollis (5), M. chamorroi (6). 5a–b: habitus; 5c–e: median lobe of aedeagus in ventral (c), dorsal (d) and lateral (e) view [0.8 mm]; 5f: antenna (apical antennomeres missing) [1.8 mm]; 5g: spermatheca [0.5 mm]. 6a–b: habitus; 6c–e: median lobe of aedeagus in ventral (c), dorsal (d) and lateral (e) view [0.8 mm]; 6f: antenna (apical antennomeres missing) [2.0 mm]; 6g: sclerites of endophallus [0.6 mm]; 6h: spermatheca [0.7 mm]. 5a–b: lectotype; 6a–b: holotype. hd: hairy dent; scI–IV: sclerites I–IV of endophallus. 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.