Biodiversity Data Journal :
Single Taxon Treatment
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Corresponding author: Jennifer C. Girón (entiminae@gmail.com)
Academic editor: Li Ren
Received: 15 Jun 2020 | Accepted: 03 Jul 2020 | Published: 09 Jul 2020
This is an open access article distributed under the terms of the CC0 Public Domain Dedication.
Citation:
Girón JC, Chamorro ML (2020) Variability and distribution of the golden-headed weevil Compsus auricephalus (Say) (Curculionidae: Entiminae: Eustylini). Biodiversity Data Journal 8: e55474. https://doi.org/10.3897/BDJ.8.e55474
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The golden-headed weevil Compsus auricephalus 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.
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 Compsus auricephalus 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.
Broad-nosed weevils, native species, morphotypes, morphological variation, host plants, distribution
Broad-nosed weevils of the subfamily Entiminae Schönherr, 1823 (
There are 55 tribes recognised within Entiminae (
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 (
The taxonomic confusion of the Eustylini became painfully evident with recent domestic and port interceptions in the U.S.A. of an unknown, colourful and eye-catching Colombian eustyline species loosely associated with imported cut flowers (L. Chamorro, pers. obs.). This eustyline species was tentatively identified in the taxonomically confused and diverse Compsus genus complex, but further identification required comparisons with type material deposited in European institutions.
A single species in the Compsus genus complex occurs in the U.S.A., the golden-headed weevil, Compsus auricephalus (Say, 1824) (
Habitus and variation of Compsus auricephalus: (A) Mexico, Veracruz (CWOC0047) dorsal, lateral, (B) Mississippi, Washington County (CWOC0045) dorsal, lateral, (C) Texas, Brooks County (CWOC0002) dorsal, lateral, (D) Mississippi, Washington County (CWOC0814) dorsal, lateral. Scale bars: 1 mm.
Even though C. auricephalus can be regarded as a highly variable species, being the only species of the genus present in the U.S.A. and recognising its variation is probably good enough to differentiate it from other U.S.A. entimines. The problem is that the genus currently has over a hundred species across its distributional range, with some of them looking quite similar to either or both of the colour morphs of C. auricephalus. This situation may lead to misidentifications, especially of Central American specimens, causing 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 re-description 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.
Over 700 specimens were directly examined (Suppl. material
Data for ASUCOB (part), CMNC, NHMUK and USNM were compiled into a DarwinCore file (Suppl. material
These datasets were also recovered through GBIF (
Computarización de la colección científica del proyecto de control biológico de malezas de CSIRO-Australia (Segura Ponce de León 2020
Elaboración de la base de datos de los ejemplares de la colección general de insectos adultos de la Dirección General de Sanidad Vegetal (
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 (
For the following collections, specimen data were obtained directly from collection’s curators and compiled into our DarwinCore file (Suppl. material
In total, 1606 specimen records are included in this study. Part of the coordinates presented in Suppl. material
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.
Habitus photographs were taken with a Visionary Digital Passport II imaging system (Visionary Digital, Los Angeles, CA), using a Canon MP-E 65mm lens f/1:2.8 1–5X macro lens mounted on a Canon 5D Mark III camera body and the Macropod Pro 3D system using Canon MP-E 65mm lens f/2.8 1-5x macro lens on a Canon 6D camera body on Focus stacking rails controlled by StackShot and Canon MT-24EX Macro Twin Lite flash units (Macroscopic Solutions, Connecticut, USA). Images of internal structures were produced by stacking images taken through a Canon EOS 5D Mark II camera attached to an AmScope SM-1TSZZ-144S stereomicroscope or a Nikon Optiphot microscope at 100× magnification. The serial images were processed using Helicon Focus 5.3 software (
The species re-description follows
Taxonomy
Family Curculionidae Latreille, 1802 (
Subfamily Entiminae Schönherr, 1823 (
Tribe Eustylini Lacordaire, 1863 (
Genus Compsus Schönherr, 1823: 1140 (
Type species: Curculio elegans Olivier, 1807: 328 (
Compsus auricephalus (Say, 1824)
Curculio auricephalus Say, 1824: 310 (
Platyomus auricephalus (Boheman 1833: 645) (new combination in
Platyomus auriceps Schönherr, 1840: 183 (
Say's original description for C. auricephalus (
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
Morphological features of Compsus auricephalus: (A–D) Texas, Garza Co. (TTU-Z_050014); scale bar: 1 mm: (A) dorsal habitus, (B) lateral habitus (s10: stria 10; s9: stria 9; i7: interstria 7; i9: interstria 9), (C) ventral habitus of female, (D) posterior view (i3: interstria 3; i5: interstria 5; i7: interstria 7; as: articular surface; ob: outer bevel; if: inner fringe), (E) Texas, Cameron Co. (TTU-Z_219291) ventral habitus of male; (F) Mississippi, Warren Co. (TTU-Z_219296), anterolateral habitus.
Head. Frons nearly flat, only very slightly transversally impressed at level of posterior margin of eyes; frons with deep, large median fovea (Fig.
Morphological features of the head of Compsus auricephalus: (A–B) Texas, Garza Co. (TTU-Z_050014): (A) dorsal view (mf: median fovea; dlm: dorsolateral margin; vlm: ventrolateral margin), (B) lateral view (os: occipital suture); (C–D) Mississippi, Warren Co. (TTU-Z_219296): (C) head, anterior view (mf: median fovea; ms: median sulcus; ds: dorsolateral sulcus; ep: epistoma; eps: epistomal setae; np: nasal plate; apm: apical margin), (D) head, ventral view (prm: prementum; os: occipital suture; atp: anterior tentorial pit; ptp: posterior tentorial pits; gs: gular suture), (E) Mississippi, Washington County (CWOC0045), dorsal view with deciduous processes (dp); (F) Texas, Brooks County (CWOC0002) dorsal, scale bar 1 mm; (G) Texas, Mason Co. (TTU-Z_219308), dorsal view with deciduous processes (dp).
Rostrum. Only very slightly wider than long (Fig.
Mouthparts. Mandibles with multiple setae along dorsal, outer and ventral areas surrounding scar (Fig.
Morphological features of Compsus auricephalus (Louisiana, Acadia Parish): (A–C) mouthparts: (A) right maxilla, ventral view (cd: cardo; st: stipes; pg: palpiger; mpm1: maxillary palpomere 1; mpm2: maxillary palpomere 2; mpm3: maxillary palpomere 3; gat: galeal teeth; ga: galea; lat: lacinial tooth; la: lacinia), (B–C) prementum, (B) dorsal view, (C) lateral view (lpm1: labial palpomere 1; lpm2: labial palpomere 2; lpm3: labial palpomere 3; lg: ligula), (D) metendosternite, posterior view (sk: stalk; fa: furcal arm; cr: crux; ds: distal sheath; at: anterior tendons; lf: longitudinal flange; hm: hemiductus), (E) hindwing (Sc: subcosta; R: radial; Rr: radial recurrent; rm: crossvein between radial system and Mr; Mr: medial recurrent; w: radial window; prs: proximal radial sclerite; rsd: distal radial sclerite; rsc: radial sclerotisation; msc: medial sclerotisation; Cu: cubital; Cu1: branch of Cu; af: apical fold; Cu2: branch of Cu; 2A: anal vein 2; 3A: anal vein 3; ac: anal cell; 4A: anal vein 4; R3: radial 3; pst: postradial stripe; ppp: posterior part of postradial stripe; h: apical hook of medial stripe; mst: medial stripe).
Antennae. With 12 antennomeres (Fig.
Thorax. Pronotum somewhat trapezoid (Fig.
Legs. (Fig.
Elytra. (Fig.
Hind wings. (Fig.
Abdomen. Abdominal ventrites (Fig.
Male terminalia. Tergite 7 1.3-times wider than long, with apical corners broadly rounded and broadly emarginate at apex; posteromedial and marginal regions darkened, with relatively thick setae; basi-medial and basi-lateral areas with fine, appressed spines. Tergite 8 subquadrate, only slightly wider than long, with apical corners broadly rounded and truncate to slightly emarginate at apex, with relatively long and thick setae throughout, except along basal fourth; apical margin in posterior view broadly triangularly emarginate. Sternite 8 (Fig.
Male genitalia of C. auricephalus: (A) abdominal sternite 8 (spr: spiculum relictum), (B) spiculum gastrale, (B1) detail of furcal arms, (C) tegmen, (C1) detail of projections of tegminal plate, (D) aedeagus, dorsal view (see dashed line D in figure 5E), (E) aedeagus, lateral view with dashed lines D and F indicating plane for figures D and F, respectively, (F) apical region of aedeagus, dorsal view (see dashed line F in figure 5E; me: mesal endophallite, vm: ventral membranes), (G) detail of basal endophallite complex, dorsal view (la: distal irregular lamina, lb: distal lateral bars), bme: basimesal endophallite, ble: basilateral endophallites).
Female terminalia. Tergite 7 1.5-times longer than wide, roughly obovate, with anterior and posterior margins broadly and uniformly round, posterior margin more narrowly so; surface sparsely covered by setae, relatively thicker along apical margin; basi-lateral areas with fine, appressed spines. Tergite 8 greatest length 1.2-times longer than greatest width, with anterior margin mesally deeply emarginate; surface gradually more coarsely punctate towards apex, each puncture bearing one seta, setae shorter along apical margin. Sternite 8 (Fig.
Female genitalia of C. auricephalus: (A–B) abdominal sternite 8 (apo: apodeme; lam: lamina), (A) ventral view, (B) lateral view, (C–D) ovipositor, (C) coxites, lateral view (sty: stylus; vs: ventral section of distal coxites; ds: dorsal section of distal coxites; dcx: distal coxites; ind: indentation; pcx: proximal coxites; gc: genital chamber; scl: sclerites) (D) dorsal view (scl: sclerites; bc: bursa copulatrix; spe: spermatheca), (E) spermatheca (ra: ramus; cl: collum; crp: corpus; cn: cornu), (F) detail of stylus.
Beyond variation in colouration (two colour morphs: green with green with pink/coppery head and legs or completely white to pale brown; see Figs
Based on this character combination (external and male genitalia), we conclude that Compsus auricephalus proper extends as far south as Zacapa, Guatemala (CMNEN00019741) and specimens of the
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
The distributional information for C. auricephalus was summarised by
Compsus auricephalus: Guatemala, Mexico, U.S.A.: Alabama (new record), Arizona (new record), Arkansas, Colorado, Florida (new record; one specimen with incomplete data: just "FLA." on label, USNM, needs confirmation), Georgia (one specimen with incomplete data: just "GA" on label, USNM, needs confirmation), Illinois (
Compsus aff. auricephalus: Costa Rica, Honduras (new record), Nicaragua, Panama.
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
As for Compsus aff. auricephalus, it is known to occur from Yoro, Honduras, south to the Canal Zone in Panama (Fig.
Compsus auricephalus has been collected in palmetto thickets and woods (
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 (
Host plants associated with Compsus auricephalus. Acronyms in the References column correspond to collections presented in Materials and Methods. Localities with an asterisk (*) correspond to Compsus aff. auricephalus, as defined by
Plant family |
Plant species |
Locality |
References |
Amaranthaceae | Beta vulgaris[Beet] | Texas | USNM |
Asteraceae |
Ambrosia |
Texas |
|
Ambrosia trifida [Giant ragweed] |
Texas | USNM | |
Baccharis neglecta[False willow] | Texas | USNM | |
Helianthus[Sunflower] | Mexico (Nuevo León) | USNM | |
Parthenium hysterophorus [Santa Maria feverfew] |
Mexico (Coahuila, Nuevo León) |
USNM |
|
Xanthium [Cocklebur] |
Mississippi |
MEM |
|
Boraginaceae |
Ehretia anacua (formerly Ehretia elliptica) [Knockaway] |
Texas |
|
Cactaceae | Opuntia leptocaulis | Texas | USNM |
Opuntia lindheimeri | Texas | USNM | |
Cannabaceae | Celtis laevigata[Sugarberry] | Texas | USNM |
Cornaceae |
Cornus sericea [Red-osier dogwood] |
Texas | USNM |
Euphorbiaceae |
Ricinus communis [Castor bean] |
Texas | USNM |
Fabaceae |
Acacia |
Texas |
|
Acacia farnesiana [Sweet acacia] |
Texas | USNM | |
Baptisia nuttalliana [Nuttall's wild indigo] |
Louisiana |
MEM |
|
Texas |
|
||
Lespedeza [Bush clovers] |
Tennessee |
USNM |
|
Leucaena pulverulenta[Mexican Leadtree] | Texas | USNM | |
Medicago sativa[Alfalfa] | Oklahoma | USNM | |
Phaseolus vulgaris [Bean foliage] |
Texas | USNM | |
Prosopis sp. | Texas | USNM | |
Prosopis juliflora | Mexico (San Luis Potosí) | USNM | |
Prosopis glandulosa [Honey Mesquite] |
Texas |
|
|
Vigna unguiculata [Black-eyed pea] |
Texas | USNM | |
Fagaceae |
Quercus [Oak] |
Oklahoma | USNM |
Gelsemiaceae |
Gelsemium sempervirens [Carolina Jessamine] |
Mississippi |
MEM |
Juglandaceae |
Carya illinoinensis [Pecan] |
Louisiana | USNM |
Mississippi |
MEM |
||
Texas | USNM | ||
Mexico (Coahuila) |
|
||
Lamiaceae |
Monarda citriodora [Lemon beebalm] |
Texas | USNM |
Lauraceae | Persea americana[Avocado foliage] | Panama* | USNM |
Malvaceae |
Gossypium [Cotton] |
Arkansas |
|
Louisiana |
USNM |
||
Mississippi |
|
||
Oklahoma |
|
||
Tennessee |
|
||
Texas | |||
Hibiscus |
Mississippi |
MEM |
|
Piperaceae | Piper sp. | Texas | USNM |
Poaceae |
Sorghum bicolor [Sorghum] |
Mexico (Nuevo León) | USNM |
Triticum [Wheat] |
Oklahoma | USNM | |
Zea [Corn] |
Mississippi | USNM | |
Nicaragua |
|
||
Polygonaceae |
Rumex crispus [Curly dock] |
Texas | USNM |
Rosaceae |
Crataegus[Hawthorn] | Louisiana | USNM |
Fragaria × ananassa [Strawberry] |
Tennessee | USNM | |
Malus domestica [Apple] |
Illinois |
|
|
Mississippi |
MEM |
||
Prunus persica [Peach] |
Louisiana | USNM | |
Illinois |
|
||
Mississippi |
MEM |
||
Pyrus [Pear] |
Mississippi |
MEM |
|
Rutaceae |
Citrus |
Texas |
|
Mexico (Nuevo León, Tamaulipas) | USNM | ||
Salicaceae |
Populus [Cottonwood] |
Tennessee | USNM |
Populus deltoides[Eastern cottonwood] | Texas | USNM | |
Santalaceae |
Phoradendron [Mistletoe] |
|
|
Phoradendron flavescens [Mistletoe] |
Texas |
|
|
Solanaceae |
Nicotiana repanda [Fiddleleaf tobacco] |
Texas | USNM |
Solanum [Potatoes] |
Mississippi |
MEM |
|
Texas | USNM (on foliage of Irish potatoes) | ||
Verbenaceae |
Lantana camara [Wild sage] |
Texas |
|
According to
According to
As for natural enemies, Tetrastichus compsivorus Crawford, 1914 (Hymenoptera: Chacidoidea,
Molecular data from the mitochondrial gene Cytochrome Oxidase subunit I (COI) was obtained for the specimen identified as USNMENT01070595 (see Suppl. material
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 (
Habitus of species in the Compsus genus complex apparently similar to C. auricephalus: (A) Oxyderces viridipes NHRS-JLKB000022891 (syntype, NHRS), (B) Compsus adonis BMNH(E)1722340 (holotype, NHMUK, (C) Compsus bellus (holotype, MNHN), (D) Oxyderces exaratus (syntype, MNHN), (E) Compsus violaceus (syntype, MNHN), (F) Compsus sulcicollis (holotype, MNHN), (G) Compsus lacteus (MNHN, white form), (H) Compsus lacteus (MNHN, green form), (I) Compsus albus (syntype MNHN), (J) Oxyderces cretaceus ZMUC00037512 (holotype, ZMUK), (K) Oxyderces mansuetus NHRS-JLKB000023017 (paratype, NHRS), (L) Compsus exanguis NHRS-JLKB000022886 (syntype, NHRS), (M) Compsus virginalis (syntype, MNHN) and (N) Oxyderces cinereus (syntype, MNHN). Scale bars: 1 mm.
Compsus albus Hustache, 1938 (
In Compsus bellus Hustache, 1938 (
Compsus divisus Hustache, 1938 (
Compsus exanguis (Boheman, 1833) (
Compsus lacteus (Fabricius, 1781) (
Compsus sulcicollis Hustache, 1938 (
Compsus violaceus Hustache, 1938 (
Compsus virginalis Faust, 1892 (
Exophthalmus carneipes Champion, 1911 (
Oxyderces cinereus (Hustache, 1938) (
Oxyderces cretaceus (Fabricius, 1792) (
Oxyderces exaratus (Hustache, 1938) (
Oxyderces mansuetus Hustache, 1938 (
Oxyderces viridipes Boheman, 1840 (
We thank the curators and collection managers who made specimens and data available to us for study: Charles O’Brien, Emmy Engaser, Sangmi Lee, Nico Franz (ASUCOB); Robert Anderson (CMNC); Nicole Gunter (CLEV); Tommy McElrath (INHS); Victoria Bayless, Nathan Lord (LSAM); Terence Schiefer (MEM); Hélène Perrin and Antoine Mantilleri (MNHN); Maxwell Barclay (NHMUK); Johannes Bergsten (NHRS); Luciana Musetti and Norman Johnson (OSUC); Karen Wright (TAMUIC); Floyd Shockley (USNM); Michael Kuhlmann (ZMUK); Alexey Solodovnikov (ZMUC): we are grateful for their patience and flexibility. This project was delayed due to the unprecedented Coronavirus pandemic of 2020. María Guadalupe del Río allowed us to use her photo of the holotype of Platyomus auriceps Schönherr, 1840. We thank Matthew Buffington, Systematic 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.
This file contains data of specimens from CLEV, CMNC, INHS, LSAM, MEM, NHMUK and USNM, which are currently not available online. It was created using the IPT template available at https://github.com/gbif/ipt/wiki/occurrenceData. Coordinates were approximated via Google Maps based on locality information.