Variability and distribution of the golden-headed weevil Compsusauricephalus (Say) (Curculionidae: Entiminae: Eustylini)

Abstract Background The golden-headed weevil Compsusauricephalus is a native and fairly widespread species across the southern U.S.A. extending through Central America south to Panama. There are two recognised morphotypes of the species: the typical green form, with pink to cupreous head and part of the legs and the uniformly white to pale brown form. There are other Central and South American species of Compsus and related genera of similar appearance that make it challenging to provide accurate identifications of introduced species at ports of entry. New information Here, we re-describe the species, provide images of the habitus, miscellaneous morphological structures and male and female genitalia. We discuss the morphological variation of Compsusauricephalus across its distributional range, by revising and updating its distributional range, based on data from entomological collections in the U.S.A. and Canada. The revised distribution of C.auricephalus extends as far south as Zacapa in Guatemala. Records south from there correspond to a different species, with affinities to C.auricephalus that we discuss and illustrate. We also discuss morphological affinities and differences with other similar species. Furthermore, we summarise information regarding the biology, host plants and natural enemies of C.auricephalus.

There are 55 tribes recognised within Entiminae (Alonso-Zarazaga and Lyal 1999), most of them distributed in particular biogeographic regions of the world (Marvaldi et al. 2014). The tribe Eustylini Lacordaire, 1863 (Lacordaire 1863) is restricted, for the most part, to the Neotropical region, grouping 23 genera and 334 described species . Eustylines are amongst the most commonly found broad-nosed weevils in Northern South America (e.g. Girón and Cardona-Duque 2018) and include many relatively large (~7 to 25 mm) and strikingly coloured species. Some eustylines are known as serious agricultural pests, such as the infamous "diaprepres root weevil", Diaprepes abbreviatus (Linnaeus, 1758) (Linnaeus 1758), which attacks the roots and foliage of citrus, sugar cane, coffee and other cultivated plants throughout the Caribbean region and Florida (Hall 1995, Simpson et al. 1996, Weissling et al. 1998, Wolcott 1922. Only in Puerto Rico, D. abbreviatus feeds on the foliage of over 40 plant species (Martorell 1945). "It is estimated that Diaprepes abbreviatus causes about 70 million dollars in damage annually in Florida. Estimates show the weevil infests more than 100,000 acres of citrus" (Weissling et al. 1998).
Species identification of Eustylini is quite challenging, partly because of their diversity and the lack of revisionary (and comprehensive) taxonomic studies for the group, but also because of the high degree of overlapping characters amongst eustyline genera. Furthermore, the limits of Eustylini, as a tribe, are still not clearly defined, as some genera in the tribe Geonemini Gistel, 1848 (Gistel 1848) exhibit quite similar morphologies and problems at ports of entry given the current inability of determining if intercepted specimens belong to a native or exotic species.
This study aims to clarify the status of Compsus auricephalus by (1) presenting a full redescription of the species with images representing its morphological characteristics and range of variation, (2) comparing C. auricephalus to externally similar species, (3) updating distributional records including a map and (4) presenting a summary of biological information including a list of host plants and natural enemies for the species, with a discussion on the status of C. auricephalus as a crop pest. The mouthparts, hind wings and male and female genitalia are described here for the first time.

Specimen data
Over 700 specimens were directly examined (Suppl. material 1 in addition to specimens listed under Materials below). Type material of miscellaneous species in the Compsus genus complex were examined in order to differentiate C. auricephalus from similarlylooking species. Examined specimens are deposited at the following institutions:  (Song and Johnson 2018).
Variability and distribution of the golden-headed weevil Compsus auricephalus ...
• UMNH Utah Museum of Natural History, University of Utah, Salt Lake City, Utah (Natural History Museum of Utah (UMNH) 2020).
• Elaboración de la base de datos de los ejemplares de la colección general de insectos adultos de la Dirección General de Sanidad Vegetal (Vega Ortiz, H E and Comisión nacional para el conocimiento y uso de la biodiversidad C 2020).
The dataset was recovered from GBIF on 5 June 2020, contains 728 occurrence records and can be downloaded from https://doi.org/10.15468/dl.rat633. 'Human observations' from iNaturalist (iNaturalist.org 2020; as opposed to 'preserved specimens', see Darwin Core terminology http://rs.tdwg.org/dwc/terms.htm) and Bugguide (VanDyk et al. 2020), as recovered from GBIF, were verified and included in our dataset, representing 124 (17%) of the GBIF records. Only two records, both based on human observations, (Oak Mountain State Park, Shelby County, Alabama [https://bugguide.net/node/view/1694325] and Fondes Amandes Rd, Port of Spain, Trinidad and Tobago [https://www.inaturalist.org/observations/ 32103921]) were excluded given that the identity of the specimens cannot be confirmed from the pictures provided.
For the following collections, specimen data were obtained directly from collection's curators and compiled into our DarwinCore file (Suppl. material 1): • In total, 1606 specimen records are included in this study. Part of the coordinates presented in Suppl. material 1 (also available at https://doi.org/10.15468/chpymx) were obtained by approximating the locality data via Google Maps (https://www.google.com/ maps). The distribution map was created using SimpleMappr (Shorthouse 2010). Collection codes, listed here, correspond to those listed in Evenhuis 2020. Information on host plants was obtained both from literature records and label data.

Morphological methods
Specimens were examined using an AmScope SM-1TSZZ-144S stereomicroscope (magnification: 3.5X-180X) and a Zeiss Discovery v8. Genitalia dissections were prepared by removing the entire abdomen from the specimen and opening it along one side; then the abdomen was submerged in a solution of 10% potassium hydroxide (KOH) and heated to 50°C overnight. Afterwards, the macerated abdomen was submerged in glacial acetic acid for 10 minutes and then rinsed with distilled water. Dissections were ultimately performed by placing the cleared abdomen on a microscope slide with a drop of glycerine. auricephalus (Schönherr 1833). The species was listed as Platyomus auriceps by Schönherr in 1840, recorded from Mexico as well (Schönherr 1840). LeConte and Horn (1876) offered a brief, but detailed description of the species, indicating its colour variation ranging from pale green with cupreous head and legs to white or pale brown, rather abundantly occurring from Georgia to Mexico and to the north in Colorado. Champion (1911) highlighted the great variation in size and colouration in C. auricephalus, attributing the colour variation to discolouration and comparing this to the situation of C. isabellinus (Boheman, 1833in Schönherr 1833 Description Body length 8-12 mm, width 3-4 mm; shape oval, length/width ratio 2.4-2.6; greatest width near mid-length of elytra in males, near posterior third in females. Integument dark brown to black; coverage composed of densely and evenly arranged, overlapping scales (Figs 1, 3A-C), mostly to completely covering integument, subcircular to distally angulate, appressed; scales uniformly pearly white to light brown (Fig. 1C, Fig. 3A-C) or iridescent light green along body with iridescent pink along dorsal surface of head and along anterior and ventral surfaces of legs (Fig. 1A, B, Fig. 3F); seta-like narrow scales sparsely and evenly arranged, relatively short and thick, recurvate, pale white to translucent.
Head. Frons nearly flat, only very slightly transversally impressed at level of posterior margin of eyes; frons with deep, large median fovea (Fig. 4A, C, mf); surface of head densely covered by overlapping scales; scales apically angulate along base of head, progressing to oval anteriorly (Fig. 4B); curved, thick setae only along dorsal surface of head. Eyes in lateral view (Fig. 4B) tear-drop shaped, 1.5-times longer than wide, with acute margin pointing antero-ventrally; eyes mostly lateral, separated from anterolateral margin of prothorax by distance slightly shorter than greatest width of eye; in dorsal view (Fig. 4A, E-G), eyes moderately convex, with inner margins slightly oblique, interocular distance 4.6-times maximum width of eye.
Thorax. Pronotum somewhat trapezoid (Fig. 3A), 1.3-times wider at base than at apex, 1.2-times wider at base than long; pronotum nearly 0.3-times length of elytra, with greatest width at base; dorsolateral margins anteriorly converging, posteriorly subparallel; posterior margin only very slightly bisinuate, with lateral areas depressed, and covered by densely arranged plumose setae. Dorsal surface of pronotum medially flattened to depressed, with dorsolateral, longitudinal, broad elevations, irregularly foveate to punctate; lateral surfaces flattened, irregularly foveate to punctate; scales appressed, evenly and densely distributed for the most part; with scattered recurvate setae, anteriorly or medially directed; median area of pronotum often posteriorly depressed. Prothorax in lateral view (Fig. 3B) subquadrate to trapezoid; anterior margin straight and slightly oblique, without postocular lobe, fringed with angulate scales and sometimes with plumose setae projecting anteriorly; postocular vibrissae absent; dorsolateral surface broadly and longitudinally elevated posteriad coxal insertion; posterolateral surface depressed. Metascutum partially covered with plumose scales, especially along posterior margin. Scutellar shield subquadrate to elongate with round corners, covered by scales. Prosternum (Fig. 3C) slightly longer than mesosternite, similar in length to metasternite; prosternum with transverse anterior and posterior sulci; procoxal cavities contiguous, 0.7-times closer to anterior than to posterior margin of prosternum; anterior margin of prosternum fringed by regular setae, plumose setae and scales. Mesosternite (Fig. 3C) with intercoxal process slightly elevated, with recurvate setae; mesocoxal cavities separated by distance nearly 0.3-times greatest width of each mesocoxal cavity. Metasternite (Fig. 3C) with median sulcus short, shallow, Y-shaped, positioned near posterior margin; metacoxal cavities separated by distance nearly 0.8-times width of each mesocoxal cavity. Metendosternite (Fig. 5D) with stalk (sk) 1.5-times longer than each furcal arm (fa); stalk somewhat triangular (wider at junction with sternum, gradually narrowing towards crux (cr)); distal sheaths (ds) well developed, as wide as widest point of crux; anterior tendons (at) inserted at dorsal margin of distal sheaths, at mesal one-third between longitudinal flange (lf) and furcal arms; furcal arms somewhat triangular, diverging, with apex slightly explanate; hemiducti (hm) well developed, ventrolaterally pointing; posterior mesal sheath extending between dorsal margin of distal sheath and mid-length of stalk.
Elytra. (Fig. 3A, B) 1.6-1.8-times longer than greatest width; greatest width near midlength in males, near posterior third in females; anterior margins jointly similar in width to posterior margin of pronotum, recessed along median third (projected along striae 1-4, corresponding to emargination of posterior margin of pronotum); humeri oblique, slightly produced; joint elytral width at humeri nearly 1.5-times wider than joint anterior elytral margin, slightly narrower than maximum width of elytra; lateral margins straight and slightly diverging along anterior half to two-thirds, then evenly curved and gradually converging along posterior third; posterior margins each rounded, forming right angle (Fig. 3D). Elytra in lateral view ( Fig. 3B) with dorsal outline subplane to slightly convex along anterior half; posterior declivity gradual, evenly convex. Elytra with longitudinallyaligned punctures forming nine complete striae and one incomplete stria (striae 9 and 10 ( Fig. 3B, s9, s10) fused near metacoxal insertion); striae narrower than interstriae; punctures separated by distance nearly twice longer than width of each puncture; each puncture with one scale or mostly covered by scales; interstriae 3, 5, 7 (Fig. 3D, i3, i5, i7) and 9 (Fig. 3B, i9) convex along most or part of their length; interstriae 1, 2, 4, 6 and 8 flat to only slightly convex, 10 strongly convex at level of metaventrite; setae similar in length to width of interstriae, recurvate, evenly distributed along interstriae, slightly denser along apical areas; scales covering entire integument, oval, overlapping, uniformly coloured.
Hind wings. (Fig. 5D) Fully developed, elongate, nearly 1.4-times longer than elytra, nearly 3.4-times longer than wide; costal margin slightly sinuate along basal half, evenly and broadly curved thereafter; apex narrowly rounded, posterior margin broadly rounded along proximal third; anal lobe not demarcated by emargination of posterior margin of wing. Alar venation well developed: subcosta (Sc), radial (R) and radial recurrent (Rr) well defined, proximal radial sclerite (prs) well developed, darkened, distal radial sclerite (drs) reduced; radial window (w) strongly reduced; radial 3 (R3) very weakly defined (as translucent line), almost reaching alar margin; post radial stripe (pst) darkened, well-defined, almost reaching alar margin; posterior part of postradial stripe (ppp) extending along apical region of wing, nearly one third length of pst, almost reaching alar margin; apical hook of medial stripe (h) conspicuous, nearly one third length of ppp, almost reaching alar margin; medial recurrent (Mr), cubital (Cu) and branch 1 of Cu (Cu1) well defined; crossvein between radial system (rm) very weakly defined; radial sclerotisation (rsc) and medial sclerotisation (msc) weakly defined; medial stripe (mst) weakly defined, slightly shorter than pst; apical fold (af) distinct, nearly reaching alar margin; branch 2 of Cu (Cu2) reduced, smaller than h, not reaching alar margin; anal vein 2 (2A) well defined, vanishing near margin; anal vein 3 (3A) short, reaching mid-length towards margin of wing, fusing with 2A to form anal cell (ac); anal vein 4 (4A) lightly sclerotised, surounded by lightly sclerotised area around base; anal area with margin broadly rounded; posterior margin of hind wing fringed by short and fine setae separated from each other by distance similar to length of one seta, fringe extending to apical fold .
Variation: Beyond variation in colouration (two colour morphs: green with green with pink/coppery head and legs or completely white to pale brown; see Figs 1, 3) and size (8-15 mm), the morphology of C. auricephalus is fairly homogeneous across the distributional range of the species in the U.S. The morphology of both the male (Fig. 6) and female (Fig. 7) genitalia is also highly conserved within the species with no noticeable differences between colour morphs, which confirms their conspecificity.
Champion (1911) highlighted that specimens from southern populations (e.g. Southern Mexico (Acapulco), Guatemala, Costa Rica, Nicaragua and Panama) were uniformly white, had a more elongate body, more produced and acuminate elytral apices and strongly costate alternating interstriae. We studied specimens with these features (Fig.  8A-B) from Costa Rica, Guatemala, Honduras, Nicaragua and Panama, including specimens studied by Champion himself; we also dissected three specimens from Panama ( Fig. 8C-E). In general, the specimens, considered by Champion as a variety of C. auricephalus, are externally similar to the northern white form and have overall similar male genitalia, but differ clearly by the following characters: brighter white colouration (Fig. 8A, B; as opposed to pearly white to pale brown), cylindrical pronotum ( Fig. 8A; as opposed to trapezoid in C. auricephalus, see Fig. 3A), conspicuously strongly costate interstriae (in comparison with moderately elevated in C. auricephalus), angulate elytral declivity ( Fig. 8B; as opposed to broadly rounded in C. auricephalus, see Fig. 3B) and acuminate elytral apices ( Fig. 8B; as opposed to rounded in C. auricephalus, see Fig. 3B). Furthermore, there are evident differences in the shape of the median lobe: median lobe pre-apically widened ( Fig. 8C; as opposed to parallel-sided throughout as in C. auricephalus, Fig. 6D); in lateral view, median lobe weakly and rather evenly curved ( Fig. 8D; as opposed to broadly and strongly curved basad of mid length, in C. auricephalus, Fig. 6E), greatest width uniform along median three-fifths ( Fig. 8D; as opposed to greatest width uniform along second third, in C. auricephalus, Fig. 6E); in dorsal view, gonopore pear-shaped ( Fig. 8C; as opposed to oval, as in C. auricephalus, Fig. 6D); basal endophallite complex with different configuration (compare Fig. 8E to Fig. 6G).  Until more studies can be performed on a broader representation, both across the geographic range and number of specimens of Champion's variety, along with a revision of a larger sample of Compsus species, we refer to this variety as Compsus aff. auricephalus as defined by Champion (1911) and refrain from naming it as new, given that, even though we have made comparisons with some similarly-looking species, we have not seen all the white species of Compsus, nor have we been able to dissect the ones we have examined externally.

Distribution
The distributional information for C. auricephalus was summarised by O'Brien and Wibmer (1982). The distributional data gathered here are mapped in Fig. 9. The updated distribution is as follows: Comments on current distribution of Compsus auricephalus. According to our specimen examination, C. auricephalus occurs north of Zacapa, Guatemala, as far west in the U.S. as Cedar City, Utah and Phoenix, Arizona, as far north as Ohio and as far east to Georgia and Florida. Most of the records are concentrated around Brownsville, Texas and along the Mississippi River. Across the U.S.A., the distribution of C. auricephalus seems to be associated with commodities such as cotton plantations (see https://en.wikipedia.org/wiki/Cotton_production_in_the_United_States). There seems to be no geographic pattern of green/white colour morphs.
Records for Florida, Georgia and Ohio (eastern outliers) are represented by single specimens with minimal information: "FLA.", "Ga." and "Ohio", respectively. We report these records here, but highlight that they need confirmation, as these might be cases of interceptions at ports of entry (e.g. Florida), incomplete information (e.g. there is an "Ohio" locality in Hamilton Co., Texas, which is in the area where the species has been recorded) or just mislabelling. Western outliers (Arizona, Colorado, New Mexico and Utah) are represented by either records from literature (see O'Brien and Wibmer 1982) or single specimens in collections. Given that there are unique records for each of these occurrences and, even though they have more detailed collecting information (see GBIF dataset at https://doi.org/10.15468/dl.rat633 and Suppl. material 1), they may be adventitious (e.g. transported with plants from elsewhere) and not part of actual established populations of the species in those regions. Data from local collections, as well as more sampling from those areas, would be required to confirm the presence of C. auricephalus in those States.
As for Compsus aff. auricephalus, it is known to occur from Yoro, Honduras, south to the Canal Zone in Panama (Fig. 9).

Ecology
Compsus auricephalus has been collected in palmetto thickets and woods (Blatchley and Leng 1916) and, according to label data, on vegetation along roads, on prairies and using a variety of methods (beating, blacklights, flight intercept traps, malaise traps, pitfall traps, sweeping, manual capture). The species has been found at elevations from sea level up to 1200 m, with most specimens collected below 100 m.

Associated plants:
Host plant records were recovered from literature, as well as from label data from specimens in collections. Host specificity in broad-nosed weevils is difficult to assess, given that the presence of adults on a particular plant does not necessarily mean that feeding occurred (Kissinger 1964

Biology
According to Blatchley and Leng (1916), citing Pierce (1916), Compsus auricephalus "lays its eggs in a mass of gummy substance on leaves and folds a portion on the leaf over them so that they are perfectly concealed. [...] The eggs hatch in seven or eight days and the larvae enter the ground to feed on the roots of plants." This behaviour matches Howden's oviposition category 9: eggs and adhesive placed in fabricated or discovered niches, usually without use of rostrum, which is typical of most "Adelognatha" (Howden 1995

Taxon discussion
Due to its variation in size and colouration (two main colour morphs: predominantly green with pink/coppery head and part of the legs or completely white to pale brown), Compsus auricephalus can be confused with a number of eustyline species from Central and South America, not only with other Compsus species, but with species of other genera in the Compsus genus complex in South America and even species in the Exophthalmus genus complex in Central America. Colouration patterns alone partly overlap with at least a dozen different species; in these instances, particularities of the colouration pattern (e.g. colouration of legs and/or elytra) along with characters of the elytral sculpture allow for differentiation. Here, we illustrate and discuss some characters useful for distinguishing C. auricephalus from look-alike species.
Compsus adonis Marshall, 1922(Marshall 1922) is a brightly-coloured species with the head, anterior margin of the pronotum, apical region of elytra and outer surfaces of the tibia covered with pink scales, with the elytra, remainder of prothorax and elytra and femora mostly green; the apices of the femora and the tarsi are covered by blue scales and the elytra have irregular areas covered by white scales blending in with the general green coverage (Fig. 10B). This very particular colouration pattern is quite different from the colourations exhibited by C. auricephalus. In addition, the less regularly distributed elytral punctation, along with the irregularly-elevated surface of the elytra and projected elytral apices in C. adonis further allows its recognition. Compsus adonis is endemic to Colombia (Wibmer and O'Brien 1986). Hustache, 1938(Hustache 1938) shares many of the characteristics present in specimens of the white form of C. auricephalus, as well as with C. aff. auricephalus, as defined by Champion (1911): body covered by uniformly-white scales, costate interstriae 3, 5 and 7, acuminate elytral apices with regularly-aligned elytral punctures. The holotype of this species has a shiny lustre throughout (Fig. 10I).

Compsus albus
Compsus albus can be differentiated by the lack of a medial sulcus along the rostrum, which is present in C. auricephalus (compare Fig. 10I vs. Figs 2, 3A, C). Compsus candidus is similar to C. albus, both species being endemic to Colombia (Wibmer and O'Brien 1986).
In Compsus bellus Hustache, 1938(Hustache 1938, the head and distal parts of the legs are covered by coppery/pink scales just as in the green form of C. auricephalus. Compsus bellus can be recognised by its combined green and white thorax and elytra, where the elytra have a broad white medial longitudinal stripe ( Fig. 10C; as opposed to either uniformly-green or uniformly-white thorax and elytra in C. auricephalus, see Figs 1, 3) and by the strongly-projected elytral apices ( Fig. 10C; apex of elytra not projected in C. auricephalus, see Fig. 3A). In addition, there are no conspicuously-elevated interstria along the elytra in C. bellus. Even though C. bellus is currently considered a junior synonym of C. adonis, by comparing both holotypes, beyond the evident differences in colouration (compare Fig. 108B vs. Fig. 10C), the elytral punctation and the length of the apical elytral projections suggest that these are, in fact, different species, although, until more detailed studies, including dissections of male and female genitalia can be performed, we refrain from making any taxonomic changes at this time. Compsus bellus is endemic to Colombia (Wibmer and O'Brien 1986).
Compsus divisus Hustache, 1938(Hustache 1938 has the head and entire legs (except the tarsi) covered by pink scales, with bluish-green scales covering thorax and elytra; it also has part of the odd-numbered elytral interstriae elevated. The round eyes in lateral view of the head, along with the presence of an elevated, glabrous and smooth longitudinal ridge along the head and rostrum would allow the recognition of C. divisus; this longitudinal ridge suggests that this species may actually be better placed in the genus Exophthalmus (Franz 2012, Zhang andFranz 2015). Compsus divisus is endemic to Colombia (Wibmer and O'Brien 1986).
Compsus exanguis (Boheman, 1833) (Schönherr 1833) is generally similar to the white form of C. auricephalus, except for the conspicuous thick setae uniformly distributed all over the surface of the body and the presence of green scales at midpoint of the anterior margin of the pronotum, scattered through the antennae, at the apex of the tibiae and along the tarsi (Fig. 10L). Compsus divisus is endemic to Peru (Wibmer and O'Brien 1986).
Compsus lacteus (Fabricius, 1781) (Fabricius 1781) has variable colour morphs within the same colour range as C. auricephalus (i.e. green and white colour forms); however, the head is never pink and the legs and antennae are always distally blue (Fig. 10G, H). Compsus lacteus has strongly-projected eyes, projected elytral apices and conspicuous setae along the surface of the prothorax and elytra, which differentiates it from C. auricephalus. Compsus lacteus is distributed in Brazil, French Guiana, Guadeloupe and Jamaica (O'Brien and Wibmer 1982, Wibmer andO'Brien 1986).
Compsus sulcicollis Hustache, 1938(Hustache 1938 has the head covered by coppery/pink scales, with the legs covered by light green and blue scales; the thorax and elytra are uniformly covered by light green scales; the surface of elytral interstriae 3 is elevated only along the elytral declivity in C. sulcicollis and the apices of the elytra are strongly projected (Fig. 10F); these features allow its differentiation from C. auricephalus. Compsus sulcicollis is endemic to Venezuela (Wibmer and O'Brien 1986). Hustache, 1938(Hustache 1938 follows the general pink head/ green body pattern of the green form of C. auricephalus; however, the rostrum of C.

Compsus violaceus
violaceus is covered by pink scales, while the frons and mid-anterior section of the pronotum are covered by purple scales; the remainder of the pronotum and anterior half of the elytra are covered by pale green scales, the posterior half of the elytra are covered mostly by white scales and the legs are covered completely by iridescent green scales (Fig. 10E). In addition, the overall body shape of C. violaceus is pyriform (Fig. 10E), as opposed to subrectangular as in C. auricephalus (Fig. 3A). Compsus violaceus is endemic to Colombia (Wibmer and O'Brien 1986). Faust, 1892(Faust 1892 is generally similar to the white form of C. auricephalus and more so to C. aff. auricephalus, as defined by Champion (1911), as it is uniformly covered by white scales, has cylindrical prothorax and acuminate elytral apices. It can be distinguished by its somewhat irregular elytral punctation and irregularly-elevated elytral surface ( Fig. 10M; as opposed to having costate oddnumbered elytral interstriae). Compsus virginalis is endemic to Venezuela (Wibmer and O'Brien 1986 Oxyderces cinereus (Hustache, 1938) (Hustache 1938) is generally similar to the white form of C. auricephalus, especially because of its elevated odd-numbered elytral interstriae. It differs by the pyriform shape of the body and the greyish colouration of the scales covering the head and the mid and lateral lines of the pronotum, along with the presence of a pair of relatively-large dark spots about mid-length on the elytra (Fig.  10N). Oxyderces cinereus is endemic to Ecuador (Wibmer and O'Brien 1986).

Compsus virginalis
Oxyderces cretaceus (Fabricius, 1792) (Fabricius 1792) is similar to the white form of Compsus auricephalus and nearly identical to C. aff. auricephalus, as defined by Champion (1911). The sculpture of the pronotum with three basal foveae, the tubercles of interstriae 3 at elytral declivity and the apical projections of the elytra clearly distinguish O. cretaceus (Fig. 10J). Oxyderces cretaceus has been recorded from Guadeloupe and Martinique (O'Brien and Wibmer 1982). Records of "Compsus auricephalus" in iNaturalist from Trinidad and Tobago (https://www.inaturalist.org/ observations/32103921) may actually correspond to O. cretaceus, but the available specimen photographs do not allow its confirmation.
Oxyderces exaratus (Hustache, 1938) (Hustache 1938) is similar to the green form of Compsus auricephalus, in the presence of pink scales covering the head and green scales covering most of the body. They differ mostly by the presence of blue scales covering the antennae and tarsi and by the rounded projections of the elytral apices which are covered by pink scales (Fig. 10D). In addition, the surface of the elytra is irregularly elevated in O. exaratus, in contrast with the elevated odd-numbered elytral interstriae typical of C. auricephalus (see Fig. 3A). Oxyderces exaratus is endemic to Colombia (Wibmer and O'Brien 1986).
Oxyderces mansuetus Hustache, 1938(Hustache 1938) is similar to the white form of Compsus auricephalus, differing by the deep punctation of both pronotum and elytra, resulting in irregularly-elevated elytral surface, especially along the posterior half of elytra in O. mansuetus (Fig. 10K). In addition, O. mansuetus has strongly projected eyes and acuminate elytral apices (Fig. 10K) and is endemic to Argentina (Wibmer and O'Brien 1986).
Oxyderces viridipes Boheman, 1840 (Schönherr 1840) is a species with a very similar colouration pattern to the green form of Compsus auricephalus, especially because of the pink colouration of the head. The fully green legs and white longitudinal band along the elytral interstriae 1 and 2, along with the sculpture of the elytra lacking elevated interstriae (Fig. 10A), clearly distinguish O. viridipes, which is endemic to Colombia (Wibmer and O'Brien 1986), quite common in Medellín and surrounding areas (see http s://www.inaturalist.org/observations?taxon_id=869547). Oxyderces viridipes has been found domestically in Pennsylvania and California (https://www.inaturalist.org/ observations/6246529) and intercepted at south-eastern ports of entry in the U.S.A.
Entomology Laboratory, USDA, for taking the necessary images of specimens required to complete this project and Elisabeth Roberts (USDA, SEL) for data entry. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA. The USDA is an equal opportunity provider and employer.