Metallactus praetorius, Sassi, 2019

Sassi, Davide, 2019, Revision of the Metallactus hamifer species-group (Coleoptera: Chrysomelidae: Cryptocephalinae), Zootaxa 4657 (2), pp. 201-245 : 234-236

Metallactus praetorius sp. nov.

( Figs 14 ; 31 )

Types. HOLOTYPE: ♂, glued, aedeagus on the same card bearing the specimen, detached abdomen and sclerites of endophallus on a separate card // “ Paraguay ” [white label, printed] // “Staatssamlung München 1975 Erwerb Coll. Machatschke ” [white label, printed] // “ Metallactus praetorius sp. nov . HOLOTYPUS D. Sassi des.” [red label, printed] // ( ZSM). PARATYPES: 1♀, abdomen heavily damaged // “fliegl [uncertain spelling, white label, handwritten] // “ Paraguay Leg. C. Fiebrig ” [white label, printed] // ( MNHUB); 1♀ // “ Jatahy Etat de Goyaz Ch. Pujol 1895-96 ” [white label, printed] // ( MNHN). Both paratypes provided with additional label: // “ Metallactus praetorius sp. nov . PARATYPUS D. Sassi des.” [red label, printed].

Etymology. Latin adjective meaning “belonging to the commander”.

Type locality. “ Paraguay ”

Distribution. Brazil, Paraguay.

Diagnosis. A Metallactus of medium size. It belongs to a subgroup characterized by a couple of longitudinal dark stripes both on pronotum and (except for M. tarsalis ) on each elytron. M. chamorroi , M. tarsalis , M. viator , M. bivitticollis , M. pollinctor , M. agonista and a color variation of M. hamifer also belong to the same subgroup. Together with M. agonista , M. chamorroi and M. tarsalis , M. praetorius is distinguishable in the dark pattern which is decidedly partly red and not totally black as in the remaining species cited above. However, this distinction, purely based on a single chromatic character and useful, at present, for diagnostic purpose, could turn out to be inconsistent if more material was available in the future. M. agonista has a unique pronotum mostly reddish or rusty, with six or four black spots lined up along longitudinal median yellow line. M. chamorroi can be distinguished from M. praetorius by the following traits: higher pronotal /elytral ratio (namely, pronotum is relatively shorter and slightly larger), more lengthened antennae and male rear tarsi, pronotal punctation stronger and also visible in middle of disc, elytral punctation generally closer, interocular distance clearly narrower, ocular line well marked by an irregular rows of punctures clearly perceptible up to canthus, head surface shinier, with more pronounced reddish pattern and stronger and more sparsely arranged punctation. Besides, in the studied specimens of M. chamorroi the elytral dark stripes are partly reddish (totally black in M. praetorius ). M. tarsalis is actually the closest species, despite the apparent clear difference in elytral color pattern of the available specimens. The most convincing difference in male is given by the interocular distance, much greater in M. praetorius . Besides, in the latter species the frontal punctuation is much more irregularly arranged.

Description of male. Habitus in Fig. 14 a–b (HT). BL = 5.0 mm, BW = 2.8 mm, PL = 1.8 mm, PW = 2.6 mm. Interocular distance 18.0% of BL.

Head light brown with lighter border along internal rim of eyes. Labrum yellow. Vertex quite dull, bare, with few punctures scattered on yellow spot. Frontoclypeal area matt, bald with dense shallowly impressed fine punctures. Ocular lines visible only along the upper rim of eyes, on frons basically obliterated. Mid-cranial suture shaped as quite large, barely delimited hollow impression, so that surrounding surface is somewhat swollen. Antennae reddish with yellow patches on first five antennomeres, slightly darkened toward apical ones.

Pronotum yellow with two large longitudinal stripes extending from anterior margin to posterior one. Those stripes are black with posterior section red towards outside. Pronotal shape tronco-conical, rather lengthened. 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 salient behind them. Surface regularly convex, moderately shiny with fine, shallow, scattered punctures on sides and along posterior margins, almost absent on central part of disc.

Scutellum reddish, moderately shiny, bald, distinctly raised, apex truncated in a straight line. Surface almost regularly covered with fine micropunctures.

Elytron surface yellow with two longitudinal black stripes extending from anterior margin to apical clivus. Inner stripe in continuity with the pronotal one, fairly tapered posteriorly. Outer stripe slender, running over humerous, tapered towards apex. Suture narrowly black. Elytral outline parallel-sided, rather short, very weakly flattened on disc. Postscutellar area not raised. Humeral callus scarcely prominent, impunctate. Surface moderately shiny with fine, shallow punctures irregularly distributed in anterior inner part of disc, laterally arranged in irregular rows. Intervals flat.

Pygidium yellow with whitish apex, with two shallow impressions on sides, rather lustrous, covered with sparse shallow punctures and whitish setae.

Inferior parts of thorax light brown, prosternum, mesosternum, metaepisterna and anterior part of metasternum perceptibly darker. Hypomera shallowly punctured, bare. Mesoepimera and mesoepisterna almost bare with scarce shallow punctures. Metaepisterna and metasternum with irregular punctation and wrinkles, bearing sparse setae. Prosternal process coarsely punctured with long setae and raised short triangular apex. Abdominal ventrites completely yellow, shallowly and sparsely punctured, with long, sparse setae. Legs light brownish, with tarsi slightly darker.

Median depression on fifth abdominal ventrite well impressed, bald and shiny. Posterior margin of fifth abdominal ventrite weakly notched. Median lobe of aedeagus ( Fig. 14 c–e) rather small, cylindrical with apex scarcely separated from the rest of aedeagus, blunt. In lateral view apex faintly bent ventrally. Hairy dents almost obliterated, barely visible, bearing scattered, rather long setae. Aedeagal ventral surface not swollen in lateral view, devoid of particular structures. Endophallus ( Fig. 14f ) with sclerite I very small, almost reduced to only sharp, slender denticle. Dorsal spicule strongly reduced to simple membranous, ribbon-like, fairly pigmented lamina. Sclerite II distinctly bent at base and moderately tapered towards apex. Arch of sclerite III short, scarcely raised. Apex of sclerite III barely separable from arch, arched and pointed, regularly tapered, not expanded on its proximal half, with long, straight, sharpened tip. Branches of sclerite IV longer than sclerite III in the folded-up structure, almost straight, with blunt, almost symmetrical, microdenticulate apex and surface fairly rugose.

Female. BL = 5.8 mm, BW = 3.3 mm, PL = 1.8–2.1 mm, PW = 2.7–2.9 mm. Interocular distance 15.5–17.2% of BL.

In the two examined specimens pronotal longitudinal stripes completely reddish.

Fifth abdominal ventrite in females with quite deep, slightly transverse pit. Bottom of pit subluster with few tiny punctures. Vasculum of spermatheca ( Fig. 14g ) robust, scarcely pigmented with straight proximal branch not swollen at base, short, swollen distal branch and botton-like apex. Ampulla not pigmented, sticking out from basal rim of proximal branch, therefore not shifted on dorsal side of vasculum. Duct insertion and sperm gland insertion barely distinct. Duct uniform in size, slender, coiled with coils thick, rather regularly arranged. Distal not coiled portion of duct rather short, straight. Insertion on bursa copulatrix small, bent, neither swollen nor pigmented.

Figures

FIGURES 14–15. M. praetorius (14), M. sekerkai (15). 14a–b: habitus; 14c–e: median lobe of aedeagus in ventral (c), dorsal (d) and lateral (e) view [0.6 mm]; 14f: sclerites of endophallus [0.4 mm]; 14g: spermatheca [0.5 mm]; 14h: antenna [1.6 mm]. 15a–b: habitus; 15c–e: median lobe of aedeagus in ventral (c), dorsal (d) and lateral (e) view [0.9 mm]; 15f: sclerites of endophallus [0.5 mm]; 15g: spermatheca [0.9 mm]; 15h: antenna [1.9 mm]. 14a–b: holotype; 15a–b: holotype. scI–IV: sclerites I–IV of endophallus; ds: dorsal spicule. Square brackets: length of scale segment.

FIGURES 27–34. Distribution maps for Metallactus hamifer species-group. M. luniger (27); M. madefactus (28); M. octoguttatus (29); M. pollinctor (30); M. praetorius (31); M. sekerkai (32); M. tarsalis (33); M. viator (34). Grey squares: localities reported in a generic way.