Stultutragus, Clarke Abstract, 2010

Clarke Abstract, Robin O. S., 2010, Bolivian Rhinotragini Iii: New Genera And Species (Coleoptera, Cerambycidae), Papéis Avulsos de Zoologia 50 (16), pp. 239-267 : 255-257

Stultutragus gen. nov.

Type species: Stultutragus mataybaphilus sp. nov. (here designated).

Diagnosis: Relatively small (usually less than 10 mm) and robust; rostrum long; inferior lobes almost contiguous in males, wider apart in females; prothorax subcylindrical, not much longer than wide, with rounded sides; pronotum strongly convex, usually with irregular surface (sulcus to either side of midline, large callus laterally, and basal constriction strong with deep fovea laterally); prosternal process almost flat; procoxal cavity closed; elytra broad and moderately long (ca. three times longer than width at humeri), flat (without humero-apical costa), sides arcuate, apex truncate to slightly oblique, and apical angles distinctly dentate; mesosternal declivity deep and abrupt; metasternum tumid, metepisternum large and triangular; abdomen cylindrical in males, broadly fusiform in females, in male urosternite V usually deeply depressed at middle and “winged” at sides, abdominal process planar with abdomen, or nearly so; legs robust and short, pro- and mesofemora robust and spiculate ventrally; middle leg hardly longer than front leg, hind leg 1.4 longer than front leg, apex of metafemora not reaching apex of elytra; metatarsomere I slightly shorter or longer, than II + III; general puncturation dense and alveolate; colouration opaque, usually strongly contrasting black and yellow.

Description: rostrum long. Eyes large and convex in males, inferior lobes slightly longer than wide (longer in females), distal margins lying on frons or close to sides of genae, proximal margins weakly oblique (strongly in females), almost contiguous in males (widely separated in females). Antennae moderately short, not reaching apex of elytra; filiform at base; antennomeres VI or VII-X serrate, distinctly broader than basal segments. Prothorax: subcylindrical, slightly longer than wide, sides rounded; front constriction feeble; basal constriction stronger. Pronotum convex; middle half to either side of midline, as far as sides of prosternum, raised into one irregularly shaped callus; area of midline, especially towards base, depressed and broad, with modest sulcus to either side of centre; side of basal constriction with single deep fovea; pronotal surface densely alveolate-punctate, lacking sexual punctures. Prosternal process almost flat; base short and narrow; apex long and triangular, or trapezoidal. Procoxal cavities closed. Mesothorax: mesosternal declivity deep and abrupt; coxal cavity open to mesepimeron. Scutellum rectangular. Elytra flat, moderately long, about three times width of humeri, shorter than abdomen, reaching middle of urosternite IV to base of V; each elytron moderately strongly narrowed to middle (sides arcuate), apices broad, distinctly toothed laterally (smaller tooth at suture); almost uniformly alveolate-punctate. Metathorax: metasternum tumid, metepisterna large and broad at base. Abdomen: cylindrical and narrow in males, broadly fusiform in females. Male urosternite V characteristic when viewed laterally: sides foliate (expanded ventrally, and prolonged into “wings”); and when viewed ventrally: these “wings” (now, looking like spines) demarcating a deep, horseshoe-shaped depression occupying half of ventral surface; abdominal process planar with, or moderately inclined to, abdomen, intimately inserted between metacoxae, moderately narrow, an equilateral triangle in shape, apex acuminate (broader and less acuminate in females). Legs: moderately robust, slightly longer from front to back (front legs rather long, hind legs not elongate), ratio 1.0:1.1:1.4; peduncles rather short; pro- and mesofemoral claves large, abrupt (but not tumid) and ventrally spiculate; metafemoral clave narrower and fusiform, not reaching apex of elytra. Protibia straight, narrow in males, gradually widening to apex, side of apex obliquely excised. Metatibia slightly flattened, only widened at extreme apex (lacking specialised pubescence or brushes). Metatarsomere I relatively short, not, or only slightly longer than II + III.

Colour: characteristic yellow and black pattern on elytra, with humeri and apical two-thirds black, normally divided into two fascia by transverse yellow band towards apex (the presence of the latter intraspecifically variable).

Discussion: Bates (1873) established the subgenus Eclipta for those species of Ommata with: legs slender; mesofemora abruptly (but not very broadly) clavate; sides of elytra subparallel, apex truncate. He divided the subgenus into two groups: A (those with abbreviated elytra) and AA (those with elytra nearly reaching apex of abdomen); but could not name them for lack of an appropriate taxon, thereby creating a situation which can only be resolved by a fundamental revision of the genus Ommata and its subgenera.

The two Bolivian species of Stultutragus fall into group AA (because their elytra nearly cover the abdomen), but present a combination of characters sufficiently different from other species of Eclipta to justify the establishment of the new genus Stultutragus , as follows: rostrum elongate and almost planar with frons (most of Bates’ group AA species rostrum is short and declivous across clypeo-frontal area); eyes very large, encroaching on antennal insertion (most of Bates’ group AA species have large eyes, but do not encroach on antennal insertions); antennae filiform basally, thickened and serrate to form long, loose club apically (many of Bates’ group AA species have similar antennae, but many are more filiform); pronotum with two large calli separated by median depression, which, itself, is delimited by a narrow sulcus to each side (not unknown among Bates’ group AA species, but should be considered atypical); sides of pronotum rounded at middle, distinctly constricted at apex and base (pronota of most of Bates’ group AA species would be described as cylindrical), side of basal constriction deeply foveate (it has not been possible to analyse this character amongst all the species of Eclipta , but those that have been examined suggest the presence of large, deep fovea should be considered atypical); elytra long, three times longer than width of humeri (among Bates’ group AA species the elytra of many species would be more than 3.5 longer than width of humeri), but not quite covering abdomen (typical of most species of Ommata , but not all), wide at apex (in most of Bates’ Gp. 2 species the elytra narrow towards apex), almost uniformly densely punctate (many of Bates’ group AA species share this character, but many do not); urosternite V with deep depression and strongly “winged” laterally (some Ommata share these characters, but few to such an extent); legs only moderately longer from front to back, the ratio 1.0:1.1:1.4 (a close ratio only approached by species of Ommata (Eclipta) belonging to, what Zajciw (1965) called, the tenuis -group). Colour combination and distribution characteristic (but see Cantharoxylymna Linsley, 1934 below). Punctures generally alveolate (probably most of Bates’ group AA species share this character, and those that do not may be considered atypical).

Lucas (1857) described Oregostoma fenestratum from Brazil (“intérieur”); the species was transferred to Ommata (Eclipta) by Bates (1873); but examination of Lucas’ original description and illustration indicate that this species may be added to Stultutragus . This new combination is established here: Ommata (Eclipta) fenestrata (Lucas, 1857) = Stultutragus fenestratus (Lucas, 1857) comb. nov.

Bates (1873) described Ommata (Eclipta) poecila and Ommata (Eclipta) xantho from Brazil (Paraná and Santa Catarina) under his group AA species; both sexes of these species have been examined by the author and found to fully comply with the diagnostic for Stultutragus . This new combination is established here: Ommata (Eclipta) poecila Bates, 1873 = Stultutragus poecilus ( Bates, 1873) comb. nov.; Ommata (Eclipta) xantho Bates, 1873 = Stultutragus xantho comb. nov.

Fisher (1947) described two varieties of this species, nigricornis and maculicollis. The latter, described by him as differing from the typical form of O. poecila as follows: antennae black, becoming brownish black towards apices, mandibles and anterior margin of head [clypeus] black, apical two-thirds of elytra black; metasternum, except anterior margin, black; abdomen uniformly yellow, except last visible sternite, which is black, and the middle and posterior tibiae entirely black; since all these differences are subject to intraspecific variation and/or typical of females, it may be necessary to eliminate this variety from the nomenclature. The former, O. poecila nigricornis , might be a valid variety (subspecies), but a photograph of Fisher’s specimen (available on the internet) suggests it may belong to a different species, and only examination of this specimen will clarify its status.

Stultutragus might seem to be closely related to, and certainly in colour is similar to, Cantharoxylymna . However, Linsley (1934) gives a brief description of the genus (based on a single female) which includes a number of diagnostic characters distinct from those of Stultutragus , as follows: antennae filiform; elytra subparallel, reaching apex of abdomen; metafemora reaching beyond apex of elytra; metatarsomere I equal in length to remaining segments together. [These characters also fit the subgenus Ommata (Agaone) Pascoe, 1859 , but, curiously, Linsley does not refer to this taxon.]

Fisher (1947) described a second species of Canthoroxlymna, C. linsleyi , which does not conform to Linsley’s description of the genus (apical antennomeres expanded and triangular, elytra only reach base of urosternite IV, metafemora not reaching apex of elytra, metatarsomere I shorter than remaining segments together), but does conform to that of Stultutragus ; the implied transfer to this genus is persuasive, and is established here: Canthorxylymna linsleyi Fisher, 1947 = Stultutragus linsleyi ( Fisher, 1947) comb. nov.

Zajciw (1965) described O. (Eclipta) bifasciata from Brazil (Espírito Santo); but examination of both sexes of this species indicate its transfer to Stultutragus : Ommata (Eclipta) bifasciata Zajciw, 1965 = Stultutragus bifasciatus ( Zajciw, 1965) comb. nov.

Peñaherrera-Leiva & Tavakilian (2003) described O. (Eclipta) cerdai from French Guiana, which is not only similar in body shape, colour, and puncturation to Stultutragus , but also shares the following structural characters: very large eyes; form of antennae; shape of prothorax and surface features of pronotum (including fossate basal depression); elytral proportions, length, and characteristics of apices (broadly truncate and spined); urosternite V deeply depressed and “winged”; and relative length of legs and proportions of metatarsomeres (and the presence of spicules on mesofemora). Again, the implied transfer to Stultutragus is persuasive, and is established here: Ommata (Eclipta) cerdai Peñaherrera-Leiva & Tavakilian, 2003 = Stultutragus cerdai ( Peñaherrera-Leiva & Tavakilian, 2003) comb. nov.

Scrutiny of photographs available on the internet suggest that O. (Eclipta) romani Aurivillius, 1919 , although lacking the contrasting colour combination, also might be placed in Stultutragus when specimens become available for examination.

For now, the genus Stultutragus contains the following eight species:

Stultutragus bifasciatus ( Zajciw, 1965) comb. nov. Brazil

Stultutragus cerdai ( Peñaherrera-Leiva & Tavakilian, 2003) comb. nov. French Guiana

Stultutragus crotonaphilus sp. nov. Bolivia, Argentina

Stultutragus fenestratus (Lucas, 1857) comb. nov. Brazil

Stultutragus linsleyi ( Fisher, 1947) comb. nov. Costa Rica

Stultutragus mataybaphilus sp. nov. Bolivia

Stultutragus poecilus ( Bates, 1873) comb. nov. Brazil

Stultutragus xantho ( Bates, 1873) comb. nov. Brazil

Etymology: from Latin stultus meaning clownish, with reference to their bright yellow and black colours.