Mylassa mirabilis, Sassi, 2025

Sassi, Davide, 2025, Taxonomic revision of the South American genus Mylassa Stål, 1867 (Coleoptera: Chrysomelidae: Cryptocephalinae) with the description of eight new species, Zootaxa 5683 (3), pp. 301-359 : 339-347

Mylassa mirabilis sp. nov.

urn:lsid:zoobank.org:act:

( Fig. 11 ; Figs. 14e ; 18d–f ; 22a–c ; 25f ; 27c )

Types. HOLOTYPE: CHILE: Ñuble: ( MSNG), ♂, body and detached abdomen glued on same card, aedeagal median lobe glued on different card, // “ CHILE CW., reg. VIII Chilan [sic!], El Carmen Los Castaños 21.11.2003 Leg. M. Snížek ” [white label, printed] // “ Museo Genova ex coll. M. Snizek acquisto 2010” [white label, printed] // “ Mylassa mirabilis sp. nov . HOLOTYPUS D. Sassi des.” [red label, printed] //. PARATYPES (8): CHILE: Ñuble: ( MSNG), 2♂ 3♀, same data of the holotype. Maule: ( MSNG), 2♀, // “ CHILE CE., reg. VII Talca, San Clemente Carralones [sic!] 25.XI.2003 Leg. M. Snížek ” [white label, printed] // “ Museo Genova ex coll. M. Snizek acquisto 2010” [white label, printed] //. ( DSPC), 1♀, // “ CHILE I.98 Alto Vilches Talca Prov. ” [white label, printed] //. All paratypes also labelled: // “ Mylassa mirabilis sp. nov . PARATYPUS D. Sassi des.” [red label, printed] //.

Type locality. El Carmen, Chillán ( Región de Ñuble , Chile) .

Etymology. The species name mirabilis derives from the Latin mirabilis (‘remarkable’ or ‘unusual’), referring to its somewhat peculiar yet distinctive appearance.

Distribution. Chile ( Maule, Ñuble).

Biological notes. No data available.

Diagnosis. For the elytral yellow pattern, Mylassa mirabilis may resemble M. postmediana : in both species, the light elytral median spot is distinctly transverse. However, in M. postmediana , this spot is more sharply defined against the background, slightly raised, and of a more pronounced yellow hue. In M. mirabilis , this spot has a more uncertain, winding pattern and is less clearly delimited against the background, with a redder colour tone. Furthermore, in M. postmediana , pronotum is more convex, and punctation is much finer. Additionally, in the latter species, setae are denser, finer, and more appressed. In M. mirabilis , setae are instead much longer and mostly erect or semi-erect. Besides, M. mirabilis differs from M. crassicollis in pronotal shape, which is less bulging and more tapered anteriorly. Aditionally, the pronotal surface is decidedly matt (shiny in M. crassicollis ). Moreover, elytral punctures are more impressed, and setae on elytral surface look longer and semi erect (appressed in M. crassicollis ).

Description of male. Habitus in Fig. 11a–b (HT). BL = 3.0– 3.3 mm, BW = 1.9 mm, PL = 1.3–1.5 mm, PW = 1.7–1.8 mm. Interocular distance 15.2–16.7 % of BL.

Head totally black. Vertex and frontoclypeal surface covered with well-impressed, fine punctation, closer on vertex and upper part of frons, more scattered on rest of surface, and long, rather thick, whitish setae; mid-cranial and frontoclypeal sutures not clearly detectable. Eyes large, only shallowly notched on inner margin with upper lobes well separated from each other. Ocular lines scarcely impressed, perceptible only along upper ocular edge. Antennae reaching elytral half when bent backwards, antennomeres robust, brown, basal antennomeres usually lighter; antennomeres 3–5 subcylindrical; 6–10 slightly flattened; 4–11 scarcely differing in length.

Pronotum totally black, convex, slightly transverse. Lateral margins narrow, not visible from above, faintly angulate behind midline, then almost straight, fairly converging towards anterior margin so that overall outline vaguely pentagonal, with maximum width just before basal margin. Posterolateral impressions long, obliquely departing from posterior margin towards sides, well impressed so that central part of disc looking fairly bulging. Pronotal surface matt, covered with close, regularly distributed, coarse but shallowly impressed punctation and long, erect, partly whitish, partly blackish setae. Posterior lobe large, slightly convex with apex truncated in straight line.

Scutellum black, bare, triangular, not raised, densely and finely punctured and setose.

Elytron black with large, wavy transversal reddish band at about middle. Such band, broader towards side, starting from suture and reaching lateral margin, where merging with slender reddish patch running along lateral edge from humeral callus to posterior clivus. Usually, second transversal reddish band along basal margin, ranging from inner border of humeral callus to suture, then extending along suture to merge with median band. Sometimes this basal band reduced or missing. Further crescent-like reddish spot on apex. Elytral outline cylindrical, regularly convex, with sides parallel, i.e. not convergent toward apex. Lateral margins narrow, not visible from above. Scutellar area not raised. Humeral callus scarcely prominent, not punctured. Elytron covered with long, erect, whitish setae, thicker behind middle and on reddish pattern; surface slightly rugulose, with punctures arranged in well-impressed, almost regular rows. Epipleura narrow, with weakly concave, slightly wrinkled surface covered with dense whitish pilosity.

Pygidium black, matt, covered by fine punctures and dense, long, appressed setae.

Ventral surface black, matt, finely and densely punctured, with dense, long, appressed setae, except almost bare and shiny posterior part of hypomera and mesoepimera. Prosternal process wide, short and transverse; sides concave, with rather small, raised denticle at middle; surface minutely punctured, with dense, long, appressed setae; posterior margin rounded.

Legs completely black. Anterior and median legs with no sexual modifications.

Fifth abdominal ventrite devoid of median depression along posterior margins. Posterior margin of fifth abdominal ventrite straight.

Median lobe of aedeagus ( Figs. 18d–f ) short, squat, dorso-ventrally flattened. Ventral surface strongly concave with no clues of median carina. Shaft terminated with blunt, short triangular apex. Setose depressions slender, shallow, scarcely delimited, extended along sides up to middle of shaft. Setigerous lamellae shaped like rectangular trapezoid, i.e., squared at one end and tapering towards aedeagal apex, bearing single line of setae along distal edge.

Female. Habitus in Fig. 11f–g . BL = 3.3–3.7 mm, BW = 2.1–2.2 mm, PL = 1.5–1.6 mm, PW = 1.8–1.9 mm. Interocular distance 18.2–18.9 % of BL.

Females differ in slightly stouter outline and larger interocular distance. Additionally, antennae are shorter and thinner, and first tarsomeres of anterior legs slightly slenderer.

Fifth abdominal ventrite with shallow pit with a flat, shiny, and shallowly punctured base.

Vasculum of spermatheca ( Fig. 25f ) hook-shaped with slender lobes. Distal lobe is longer than proximal one, mildly curved with sharp apex. Ampulla long, very slender, almost threadlike, slightly broadened at apex. Duct insertion fully separate from sperm gland insertion; the latter is sitting on apex of ampulla. Duct fine, long, not coiled, loosely meandering; insertion on bursa copulatrix short, fairly thickened without forming long rigid sleeve.

Figures

FIGURE 11. Mylassa mirabilis. a–c: male, habitus in dorsal (a), lateral (b) and frontal (c) view (HT, El Carmen, Chillán, Ñuble, Chile); d: frontal view (female, PT, Alto Vilches Talca Prov., Maule, Chile); e–g: colour variations (e: male, PT, El Carmen, Chillán, Ñuble, Chile; f: female, PT, El Carmen, Chillán, Ñuble, Chile; g: female, PT, Alto Vilches Talca Prov., Maule, Chile). Images not to scale.

FIGURE 14. Pronotum. a: Mylassa daccordii (PT, Cord. Lonquimay Sierra Nevada, Araucanía, Chile); b: M. postmediana (PT, Algarrobo, Valparaíso, Chile); c: M. longicornis (PT, Parque Nacional La Campana, Valparaíso, Chile); d: M. ferruginea (HT, “Paraguay”); e: M. mirabilis (PT, El Carmen, Ñuble, Chile). Images not to scale.

FIGURE 18. Median lobe of the aedeagus in ventral (left), dorsoapical(center) and lateral (right) views.a–c:Mylassa longicornis (HT, Parque Nacional La Campana, Valparaíso, Chile); d–f: M. mirabilis (HT, El Carmen, Ñuble, Chile).All images in the figure courtesy of Michele Zilioli (MSNM).

FIGURE 22. Median lobe of the aedeagus with everted endophallus. Mylassa mirabilis (PT, El Carmen, Ñuble, Chile), in ventral (a), dorsal (b) and lateral (c) views [scale bar = 0.5 mm]. All images in the figure courtesy of Maurizio Bollino (Lecce).

FIGURE 25. Spermatheca. a: Mylassa fuliginosa [scale bar = 0.4 mm]; b: M. flavolimbata [scale bar = 0.4 mm]; c: M. daccordii [scale bar = 0.4 mm]; d: Mylassa longicornis [scale bar = 0.3 mm]; e: M. ferruginea [scale bar = 0.6 mm]; f: M. mirabilis [scale bar = 0.5 mm].

FIGURE 27. Distribution maps. a: Mylassa monrosi; b: M. fuliginosa (circle), M. longicornis (stars), M. ferruginea (large star); c: M. mirabilis (circles), M. postmediana (star); d: M. flavolimbata (circles), M. daccordii (stars). Large star in Fig. 27b (M. ferruginea): available data indicate the presence in Paraguay, but without precise locality information.