Malcho Mondaca and Beéche, 2022

Mondaca, José & Beéche, Marcos, 2022, A new genus for Stromatium chilensis Cerda, 1968 (Coleoptera: Cerambycidae: Cerambycinae: Hesperophanini) from Chile, Insecta Mundi 2022 (930), pp. 1-7 : 2-3

Malcho Mondaca and Beéche , new genus

Type species. Stromatium chilensis Cerda, 1968 , here designated.

Description. Medium size (less than 12 mm in the type species). Body long and narrow, dorsally convex. Head. Transverse, prognathous, punctate, scarsely setose. Clypeus transversely long and narrow, frontoclypeal suture visible. Eyes large, not divided, coarsely facetted, protruding laterally. Mandibles small, angled and rounded externally, without internal mesal tooth, with apex acute. Maxillary palpi moderately long; last palpomere flattened, subtriangular. Labial palpi short, last palpomere flattened, subtriangular. Antennal tubercles elevated, slightly acuminate distally. Antennae 11-segmented, filiform, with small apical spine on inner side of antennomeres III– V; antennomeres VI–XI unarmed, with erect variably long setae on inner margin; antennomere III not sulcate or carinate dorsally; male with last three apical antennomeres surpassing elytral apex; female with antennae reaching or slightly surpassing elytral apex. Scape elongate, reaching anterior margin of pronotum, gradually widened distally; pedicel cupiform, longer than wide; antennomere III longer than scape and pedicel combined, and longer than antennomere IV. Prothorax. Subcylindrical, slightly longer than wide, slightly narrowing anteriorly and posteriorly; sides and dorsal surface with rounded gibbosity, densely punctate and scarcely setose, except smooth anterior region of prosternum; piliferous punctures subcircular, variable in size. Pronotum coarsely punctate, usually glabrous or with a few erect setae; dorsal smooth central area present or absent (variable intraspecifically). Scutellum rounded at apex. Elytra. Subparallel-sided, with humeral angles prominent; dorsal surface smooth, nearly glabrous, without integumentary processes and eburneous maculae; coarsely, deeply punctate on basal third, then gradually finer and sparser toward apex; covering abdomen, not exposing pygidium in both sexes; elytral apices truncate, with a small projection on sutural angle. Legs. Procoxa spheroidal; procoxal cavities open posteriorly; mesocoxal cavities open. Femora slightly pedunculate-clavate, with metafemoral club not abruptly widened, flattened, broadest near middle; metafemur not surpassing apex of abdomen. Tibial apex with two small spurs. Metatarsomere I longer than II–V combined. Abdomen. Ventrites scarcely setose, with some long and erect setae laterally; ventrite I longer than the rest, II–V subequal in length, V truncate apically.

Remarks. Malcho new genus can be included in the key from Martins and Galileo (1999), in the alternative of couplet “5” with the genus Paraliostola Tavakilian and Monné, 1991 . It differs by the smaller body width, and the absence of black elytral spots, in addition to the presence of a small spine on the inner apex of the antennomeres III–V.

Tribal classification. The only known species in the genus Malcho new genus has a small spine on the inner apex of the antennomeres III–V, one of the features that is diagnostic of Elaphidiini ( Fig. 1 ), and a character that also occurs in other Chilean genera of Cerambycidae such as Apyrauna Martins, 2005 (Elaphidiini) , Cotyachryson Martins, 2002 (Achrysonini) , and Xenocompsa Martins, 1965 (Achrysonini) . Therefore, it will be necessary to reevaluate this and other morphological characters that allow establishing with greater certainty a correct tribal assignment.

Based on this morphological incongruity, Malcho new genus must remain provisionally in the tribe Hesperophanini until more detailed morphological and molecular studies are conducted that confirm or discard its true tribal position.

Etymology. The name Malcho is in reference to the “Fundo Malcho ”, the locality where the type series of this taxon was collected. Masculine gender.

Figures

Figure 1. Right antenna of Malcho chilensis showing the spine on the inner side of antennomeres III–V.