Mylassa longicornis, 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 : 337-338

Mylassa longicornis sp. nov.

urn:lsid:zoobank.org:act:A4F4A450-BF1E-4694-906E-7C922FBDC083

( Figs. 10d–f ; 14c ; 18a–c ; 25d ; 27b )

Types. HOLOTYPE: CHILE: Valparaíso: ( NMPC), ♂, body and detached abdomen glued on same card, median lobe glued on different card, // “ CHILE: V. Paraiso Region PN La Campana, Sector Granizo Sendero El Andista, above 2 do Aquada 32°58.2[ʹ] S 71° 7.5 [ʹ] W; 900 m; 22.xi.2013; Fikáček, Kment & Vondráček CH06” [white label, printed] // “evergreen forest and deciduous forest on slopes, sweeping + beating of trees ( Escallonia , Retamilla [sic] ephedra , Nothofagus macrocarpa , Kageneckia , etc.” [white label, printed] // “ Mylassa longicornis sp. nov. HOLOTYPUS D. Sassi des.” [red label, printed] //. PARATYPES (30): CHILE: Valparaíso: 3 ♂, ( NMPC & DSPC), same data of the holotype. Araucanía: ( BMNH), 1♂, // “Chile: El Radal. L.E.Pena, 28.30. xi.1957. B.M. 1964-582. 1100m.” white label, partly handwritten] //. Maule: ( MSNG), 1♀, // “ CHILE CE., reg. VII Curico E of Potrero Grande 10.12.2003 Leg. M. Snížek ” [white label, printed] // “ Museo Genova ex coll. M. Snizek acquisto 2010” [white label, printed] //. Santiago: ( IAPC), 1♀, // “ CHILE, LaViluma, SE Melipilla 15/ 17.XII.1987 ” [white label, printed] //; ( IAPC), 16♂ 8♀, // “ CHILE, Rancagua Q.la Goyana s.e. Aculeo 1800m xi.1981 ” [white label, printed]. All Paratypes also labelled: // “ Mylassa longicornis sp. nov. PARATYPUS D. Sassi des.” [red label, printed] //.

Type locality. Parque Nacional La Campana (Región de Valparaíso, Chile) .

Etymology. The species name derives from the Latin longus (‘long’) and cornu (‘horn’ or ‘antenna’), referring to the particularly long antennae of the male.

Distribution. Chile (Araucanía, Maule, Santiago, Valparaíso). The Región Metropolitana de Santiago is reported in an observation on iNaturalist.

Biological notes. According to label data, a few specimens examined in this study were collected by beating various tree or shrub species. Noteworthy among these are Retanilla ephedra (Vent.) Brongn. ( Rhamnaceae ) and Nothofagus antarctica (Forst) Oerst. ( Nothofagaceae ), as also reported for other species of genus Mylassa .

Diagnosis. It differs from M. flavolimbata in the different shape of the elytral median yellow spots, which is slightly transverse (longitudinally arranged in M. flavolimbata ). Besides, in M. longicornis the ventral surface of the aedeagal median lobe is more convex, the setigerous lamellae are larger and triangular (elliptical in M. flavolimbata ) and bear longer setae. In the single female studied, the light elytral spots are slightly larger, and the pattern closely resembles that of many females of M. rubronotata . However, in the latter, the colour tends to be ochreous, while it is distinctly yellow in M. longicornis . Furthermore, and more significantly, in females of M. rubronotata , the punctation on both the pronotum and elytra is finer, and the antennae are decidedly shorter, and folded backward, barely reaching the midpoint of the elytra. In M. longicornis , when folded backward, the antennae reach the elytral apex.

Description of male. Habitus in Figs. 10d–f (PT). BL = 2.7–2.8 mm, BW = 1.7 mm, PL = 1.1–1.2 mm, PW = 1.6 mm. Interocular distance 17.9–18.5 % of BL.

Head totally black. Vertex and frontoclypeal surface covered with well-impressed, regularly distributed punctation and scattered short 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 long, reaching elytral clivus when bent backwards, antennomeres black, sometimes with lighter patches, especially on basal segments, minutely setose, slender, 5–10 slightly flattened, 4–11 scarcely differing in length.

Pronotum totally black, convex, slightly transverse. Lateral margins narrow, not visible from above, almost straight, weakly converging towards anterior margin so that overall outline almost square, with maximum width at about 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 almost bare, covered with close, regularly distributed, coarse but shallowly impressed punctation. Posterior lobe slender, slightly convex with apex truncated in straight line.

Scutellum black, bare, triangular, sometimes apex separated by transversal furrow, not raised, bare, finely punctured.

Elytron black with large, elliptical, transversally arranged yellow spot just before middle, almost reaching humeral callus, extended from second rows of punctures to lateral margin; further yellow spot at apex. Elytral outline cylindrical, regularly convex, with sides parallel, i.e. not convergent toward apex. Lateral margins narrow, partly visible from above. Scutellar area not raised. Humeral callus scarcely prominent, not punctured. Elytral surface almost bare, slightly rugulose, with punctures arranged in well-impressed, almost regular rows. Epipleura narrow, with weakly concave, slightly wrinkled surface.

Pygidium black, covered by fine punctures and scattered, 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, transversally depressed at centre; sides with sharp, thorn-shaped denticle behind middle; posterior margin raised at middle in sharp, laterally flattened process; surface minutely punctured, with sparse, long setae.

Legs completely black. Anterior tibiae mildly curved inward and fairly expanded towards apex. Median tibiae slightly expanded as well at distal end. Both anterior and median devoid of apical or subapical tooth-like process.

Fifth abdominal ventrite strongly concave in lateral view, devoid of median depression along posterior margins. Posterior margin of fifth abdominal ventrite straight.

Median lobe of aedeagus ( Figs. 18a–c ) short, squat. Ventral surface concave with smooth surface. Shaft terminated with blunt triangular apical edge. Setose depressions slender, shallow, scarcely delimited, with few sort setae and sparse very fine punctures. Setose lamellae small, roughly triangular, bearing short setae lined in two rows.

Female. Habitus in Figs. 10g –h (HT). BL = 3.1 mm, BW = 1.9 mm, PL = 1.3 mm, PW = 1.8 mm. Interocular distance 22.6 % of BL.

Females differ in larger size, stouter outline, slightly larger ocular distance, anterior tibiae not modified and shorter antennae.

Fifth abdominal ventrite in females with shallow rounded pit with a flat, bald, scarcely punctured base.

Vasculum of spermatheca ( Fig. 25d ) slender, hook-shaped, with proximal and distal lobes not swollen, the latter slightly shorter, mildly tapered into pointed apex. Ampulla lengthened, cylindrical. Duct insertion and sperm gland insertion fully separate, the latter sitting at proximal end of ampulla. Duct fine, short, not coiled, with single turn near vasculum. Proximal section embedded in thickened, rigid sleeve.

Remarks. A picture of a living specimen of this species is available on iNaturalist (https://www.inaturalist.org/ observations/49140499) reported from Alhué, (Región Metropolitana de Santiago, Chile) at an elevation of about 2000 m a.s.l.

Figures

FIGURE 10. Mylassa postmediana. a–c: male, habitus in dorsal (a), lateral (b) and frontal (c) view (PT, Algarrobo, Valparaíso, Chile). Mylassa longicornis. d–f: male, habitus in dorsal (d), lateral (e) and frontal (f) view (PT, Parque Nacional La Campana, Valparaíso, Chile); g–h: female, habitus in dorsal (g) and frontal (h) view (PT, Curico E of Potrero Grande, 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 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.