Chicanatonus Bezark and Santo-Silva, 2023

Bezark, Larry G. & Santos-Silva, Antonio, 2023, New species, synonymies and transfers in Neotropical Lamiinae (Coleoptera: Cerambycidae), Insecta Mundi 2023 (993), pp. 1-26 : 11

Chicanatonus Bezark and Santo-Silva , new genus

Type species. Chicanatonus hovorei new species, here designated.

Etymology. Chicanatonus , anagram of “ Acanthocinus ,” the type genus of Acanthocinini . Masculine gender.

Description. Female. Body moderately elongate, convex, less than 10 mm in the type species. Frons quadrate. Eyes moderately coarsely faceted; upper eye lobes narrow, distance between them about equal to width of one upper lobe; lower eye lobes longer than genae. Antennae 11-segmented, distinctly longer than body; scape gradually, distinctly widened from base to apex, without apical cicatrix or projections, almost reaching posterior margin of prothorax, with sparse erect setae ventrally; pedicel cylindrical, slightly wider than long, with sparse erect setae ventrally; antennomeres III–XI filiform, without tufts of setae, with sparse, thick, erect setae ventrally, thick setae absent on distal segments, without projections apically. Prothorax wider than long; sides slightly rounded, gradually divergent from anterolateral angles to lateral tubercles, then subparallel-sided toward posterolateral angles; lateral tubercles located about beginning of posterior third, as continuation of margin, with apex moderately acute and slightly directed backward. Pronotum without tubercles; with a row of coarse punctures posteriorly, punctures following toward sides of prothorax. Prosternal process distinctly narrowed centrally, with its narrowest area about one-fourth procoxal width. Sides of mesoventral process convergent from base to posterior quarter, then distinctly widened; apex almost as wide as mesocoxa. Elytra without tubercles; outer sides slightly convergent from humerus to apex, more distinctly from middle; apex truncate, slightly oblique, with outer and sutural angles rounded; humeral angles distinct, not projected; centrobasal crest absent; humeral and dorsal carinae absent; with long, erect setae. Femora pedunculate-clavate, metafemoral club more gradually widened and proportionally more slender than meso- and metafemoral club, without long and abundant erect setae; profemora without modifications; metafemora not reaching elytral apex. Metatarsomere I about as long as II–III together. Last abdominal tergite and abdominal ventrite 5 distinctly longer than ventrites 2–4 together; apex of last tergite and ventrite 5 widely emarginate centrally.

Remarks. The key by Monné et al. (2020c) leads the new genus to Alcidion Sturm, 1843 (alternative of couplet “33”). Alcidion is a problematic genus including species with different body shape, with variable apex of abdomen in females (from slightly to moderately elongate), different prothoracic shape, and elytra with or without dorsal carina. However, Chicanatonus new genus differs from Alcidion by the elytra without dorsal carina (present in many species of Alcidion , including in A. humeralis (Perty, 1832) the type species), but especially by the last abdominal tergite and ventrite 5 distinctly longer than ventrites 2–4 together (distinctly shorter in Alcidion ). Following the key by Monné et al. (2020b), Chicanatonus new genus can be included in the alternative of couplet “34” with Oxathres Bates, 1864 , another genus including species with different body and prothoracic shape. However, the apex of the last tergite in females is acute in females of Oxathres (truncate and centrally emarginate in females of Chicanatonus new genus). Using the key by Dillon (1956), the new genus can be included in the alternative of couplet “14,” with Graphisurus Kirby, 1837 ( Fig. 28, 33–34 ). These two genera can be separated by the apex of the last tergite in female truncate and emarginate ( Fig. 25 ) in the new genus (acute ( Fig. 33 ) in Graphisurus ), lateral tubercles of prothorax acute and slightly directed backward (blunt and not directed backward in Graphisurus ), and metatarsomere I ( Fig. 26 ) about as long as II–III together (distinctly longer ( Fig. 28 ) than II–III together in Graphisurus ). The key by Linsley and Chemsak (1995) leads the new genus to Urographis Horn, 1880 (= Graphisurus ), if the apex of the lateral tubercles of the prothorax is considered as obtuse, and to Valenus Casey, 1891 and Dectes LeConte, 1852 , with tubercles considered acute (which they are). Chicanatonus new genus differs from Valenus by the distance between upper eye lobes equal to about width of one upper lobe (more than twice width of one upper lobe in Valenus ), last tergite and ventrite 5 very elongate, distinctly surpassing elytral apex (short, not or at most slightly surpassing elytral apex in Valenus ), and mesoventral process distinctly wider than central area of prosternal process (slightly wider in Valenus ). The new genus differs from Dectes by the stouter body (cylindrical in Dectes ), prothorax distinctly transverse (at most slightly transverse in Dectes ), prosternal process not laminiform (laminiform in Dectes ), and maximum width of the mesosternal process almost as wide as mesocoxal cavity (distinctly narrower in Dectes ). Chicanatonus new genus also resembles females of Antecrurisa Gilmour, 1960 ( Fig. 27, 29–32 ). Although males of Antecrurisa differ from those of Graphisurus only by the shape of the ventral surface of the profemora ( Fig. 29 ), abruptly narrowed and depressed on posterior 2/3, the females have the profemora without modification and thus, cannot be separated from those of Graphisurus , especially from G. triangulifer (Haldeman, 1847) . Therefore, Chicanatonus new genus differs from Antecrurisa (females) by the metatarsomere I about as long as II–III together (distinctly longer ( Fig. 27 ) than II–III together in Graphisurus ), and by the apex of the last abdominal tergite truncate and emarginate (acute ( Fig. 31 ) in Antecrurisa ).

Figures

Figures 26–34. Acanthocinini. 26–28) Metatarsus. 26) Chicanatonus hovorei, new genus, new species, holotype female. 27) Antecrurisa apicalis (Bates, 1864), female from Mexico (Quintana Roo). 28) Graphisurus vexillaris (Bates, 1872), male from Costa Rica. 29–32) Antecrurisa apicalis. 29) Male from Guatemala (Suchitepequez), frontal view. 30) Female from Mexico (Quintana Roo), profemur and protibia. 31) Female from Mexico (Quintana Roo), last tergite. 32) Female from Mexico (Quintana Roo), ventrite 5. 33–34) Graphisurus vexillaris (Bates, 1872), female from Costa Rica. 33) Last tergite. 34) Ventrite 5.

Figures 20–25. Chicanatonus hovorei, new genus, new species, holotype female. 20) Dorsal habitus. 21) Ventral habitus. 22) Lateral habitus. 23) Head, frontal view. 24) Ventrite 5. 25) Last tergite.