Mylassa daccordii, 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 : 332-334

Mylassa daccordii sp. nov.

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( Fig. 9 ; Figs. 14a ; 17d–f ; 25c ; 27d )

Types. HOLOTYPE: CHILE: Araucanía: ( MSNM), ♂, body, aedeagus and detached abdomen glued on same card // “CHILE I-2000 Malleco Prov. Lonquimay” [white label, printed] // “ Mylassa daccordii sp. nov . HOLOTYPUS D.

Sassi des.” [red label, printed] //. PARATYPES (55): CHILE: Araucanía: (MSNM & DSPC & MDPC), 30m 22♀, same data of the holotypes (for some specimens the date is reported as “I-00”), //; ( DSPC) , 1♀, // “CILE [sic] Las Raices Cautin XII-94” [white label, printed] //; ( DSPC), 1♀, // “CHILE I-1962 Cord. Lonquimay Sierra Nevada” [white label, printed] //; 1♂, ( USNMNH) // “ Las Cabinas [?] 10.XII.54, 1480m Chile leg. Pena ” [white label, partly printed] // “ F. Monrós Collection 1959” [white label, printed] // “ Pachybrachis segethi (Philippi) det. I.S. Askevold 1993” [white label, partly printed] //. All paratypes also labelled: // “ Mylassa daccordii sp. nov. PARATYPUS D. Sassi des.” [red label, printed] // .

Type locality. Lonquimay ( Provincia de Malleco , Región de la Araucanía, Chile) .

Etymology. The species is named in honor of Mauro Daccordi, an esteemed chrysomelid specialist, in recognition of his significant contributions to the study of Chrysomelidae .

Distribution. Chile ( Araucanía).

Biological notes. No data available.

Diagnosis. Together with Mylassa flavolimbata , M. longicornis , and M. postmediana , this species belongs to the subgroup of small-sized species with elytra black and two (lateral-median and apical) yellow spots. Among them, Mylassa daccordii is characterized by relatively short and flattened antennomeres in males. Additionally, pronotal punctation is stronger and less closely arranged, and elytral yellow spots are distinctly smaller.

Description of male. Habitus in Figs. 9e (HT), 9f (LT). BL = 2.5–2.7 mm, BW = 1.6–1.9 mm, PL = 0.9–1.0 mm, PW = 1.3–1.4 mm. Interocular distance 14.8–20.0 % of BL.

Head totally black. Vertex and frontoclypeal surface bare, covered with well-impressed, regularly distributed punctation, mid-cranial and frontoclypeal sutures not clearly detectable. Eyes large, bulging, only shallowly notched on inner margin with upper lobes well separated from each other. Ocular lines scarcely impressed, barely visible. Antennae short, reaching elytral half when bent backwards, antennomeres robust, black, sometimes with lighter patches, especially on basal segments, minutely setose; antennomeres 4–11 cylindrical, scarcely different from each other in length and shape.

Pronotum totally black, regularly convex, bulging. Lateral margins narrow, not visible from above, almost straight, regularly converging towards anterior margin so that maximum width about at basal margin. Posterolateral impressions short and weakly impressed, close to posterior margin. Pronotal surface bare, covered with close, regularly distributed shallow but coarse punctation. Posterior lobe slender, slightly convex with apex truncated in straight line.

Scutellum black, triangular, pointed, not raised, bare, very minutely and sparsely punctured.

Elytron black with elliptical, transverse yellow spot just before middle, between fifth and ninth rows of punctures; further yellow spot at 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 prominent, not punctured. Elytral surface bare, with punctures arranged in well-impressed, almost regular rows. Epipleura narrow, with plane or weakly concave, slightly rugose surface.

Pygidium black, matt, covered by very fine punctures and short, appressed setae.

Ventral surface black, matt, finely and densely punctured, with short, appressed setae, except scarcely setose, shiny posterior part of hypomera. Prosternal process wide, short and transverse; sides with sharp denticle at middle; surface minutely punctured, with scarce, short setae; posterior margin rounded, almost smooth, devoid of punctures and setae.

Legs completely black, 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. 17d–f ) short, squat. Ventral surface mildly concave, smooth, with no clues of median carina. Shaft terminated with blunt, very short, slightly arched apex. Setose depressions slender, shallow, scarcely delimited, extended along sides up to middle of shaft. Setigerous lamellae small, triangular, bearing few short setae.

Female. Habitus in Figs. 9a–b . BL = 3.0– 3.1 mm, BW = 1.9–2.0 mm, PL = 1.1–1.2 mm, PW = 1.7 mm. Interocular distance 19.4–20.0 % of BL.

Females differ in larger size, the stouter outline, and shorter antennae which scarcely overrun midline when bent backwards.

Fifth abdominal ventrite in females with shallow rounded pit with a flat, bald, not punctured base.

Vasculum of spermatheca ( Fig. 25c ) slender, hook-shaped, with proximal and distal lobes not swollen, the latter one slightly shorter, mildly tapered into pointed, downturned apex. Ampulla lengthened, cylindrical, pigmented. Duct insertion and sperm gland insertion fully separate, the latter sitting at proximal end of ampulla. Duct fine, short, not coiled but forming a loose tangle close to basis of vasculum. Proximal section is embedded in a thickened, rigid sleeve.

Remarks. One specimen in USNMNH bears a handwritten label by I.S. Askevold, which would identify it as belonging to Pachybrachis segethi Philippi, 1859 . Unfortunately, the type material of the species described by Philippi (1859), despite repeated attempts, is currently untraceable. However, based on scant original description, P. segethi should be quite different from the species described here.

Figures

FIGURE 9. Mylassa daccordii. a–c: female, habitus in dorsal (a), lateral (b) and frontal (c) view (PT, Cord. Lonquimay Sierra Nevada, Araucanía, Chile); d: frontal view, male (HT, Lonquimay, Araucanía, Chile); e–f: colour variations (e: male, HT, Lonquimay, Araucanía, Chile; f: male, PT, Las Cabinas, 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 17. Median lobe of the aedeagus in ventral (left), dorsoapical (center) and lateral (right) views. a–c: Mylassa flavolimbata (PT, Embalse Bullileo, Ñuble, Chile); d–f: M. daccordii (PT, Lonquimay, Araucanía Chile); g–i: M. postmediana (HT, Algarrobo, Valparaíso, Chile). All images in the figure courtesy of Michele Zilioli (MSNM).

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.