Research Article |
Corresponding author: Robert S. Anderson ( randerson@mus-nature.ca ) Academic editor: Miguel Alonso-Zarazaga
© 2018 Robert S. Anderson, Michael S. Caterino.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Anderson RS, Caterino MS (2018) A revision of the genus Eurhoptus LeConte, 1876 (Curculionidae, Cryptorhynchinae) of America north of Mexico. ZooKeys 787: 37-80. https://doi.org/10.3897/zookeys.787.26948
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The genus Eurhoptus LeConte, 1876 is revised for America north of Mexico. Eight species are recognized including E. pyriformis LeConte, 1876, E. sordidus (LeConte, 1876), E. curtus (Hamilton, 1893), resurrected name, and five new species as follows: E. rileyi new species (type locality, Texas, Hidalgo County, Bentsen Rio Grande State Park), E. imbricatus new species (type locality, Texas, Bandera County, Lost Maples State Natural Area), E. cariniventris new species (type locality, Texas, Bandera County, Lost Maples State Natural Area), E. occidentalis new species (type locality, Texas, Brewster County, Big Bend National Park), and E. aenigmaticus new species (type locality, Alabama, Winston County, Bankhead National Forest). Descriptions or redescriptions, and images of taxonomically important structures are presented for all species. A key to the eight species is included.
Biodiversity, new species, phylogeny, species discovery, taxonomy, weevils
The genus Eurhoptus was established by LeConte in 1876 for the species E. pyriformis LeConte, 1876. The genus was differentiated from the closely related Acalles Schoenherr, 1825 by the pear-shaped body and a stouter antennal club.
At least three new species have been known to occur in the U.S. for some time (
The natural history of Eurhoptus is essentially unknown. The adults are frequently sifted from various types of leaf litter, where they may feed on fungus-infested plant debris, as some related taxa are thought to do (
Standard taxonomic procedures for the examination of pinned specimens have been used. Maps were prepared with Simplemappr (http://www.simplemappr.net). Species identifications of outlying individuals were confirmed. GenBank numbers, label data, and voucher numbers for all sequences analyzed here are provided in Suppl. material
BMNH The Natural History Museum, London, England
CWOB Charles W. O’Brien Insect Collection, Green Valley, Arizona, U.S.A.
EGRC Edward G. Riley Insect Collection, College Station, Texas, U.S.A.
KSC Kyle Schnepp Collection, Gainesville, Florida, U.S.A.
MEM Mississippi State Entomology Museum, Mississippi, Mississippi, U.S.A.
In part to test the distinctiveness of the species we have recognized among Nearctic Eurhoptus, we undertook a molecular phylogenetic analysis including multiple representatives where possible, of as many species as possible. Our main questions regarded the distinctiveness of a few morphological variants related to both E. pyriformis and E. sordidus. Our data set largely relies on data generated for a population level analysis of E. pyriformis in the southern Appalachians (
We dissected each specimen and used the GeneJet Genomic DNA Purification Kit (ThermoFisher Scientific, Waltham, MA) to extract DNA from the dissected head and prothorax. Following tissue digestion, we removed the remaining exoskeleton and mounted the body parts as vouchers. Most vouchers are deposited in the Clemson University Arthropod Collection. We sequenced portions of four genes for this analysis. We sequenced 826 bp of the mitochondrial cytochrome oxidase I (COI) gene, which is represented in 78 individuals. The portion sequenced is from the 5’ half of the gene, mainly using the primers C1-J-2183 (‘Jerry’) and TL2-N-3014 (‘Pat’; both from
Sequences of COI were length invariant, and alignment was trivial. Sequences of all other markers included length variation. These were aligned using MAFFT online (
There is a high degree of molecular diversity and divergence among species and populations of Nearctic Eurhoptus. Uncorrected pairwise divergences in COI exceeded 10% between all of the species we recognize below (for which we had data). Some still contain intraspecific divergences approaching this. However, the higher divergences in these cases are spanned by intervening populations, and are united by morphology, and we do not yet see clear grounds for further separation.
Both parsimony and Bayesian analyses (see Figure
One of a number of equally parsimonious trees (numerous rearrangments within species were equally parsimonious). Numbers on branches represent Bayesian posterior probabilities >75% for major clades. Terminal units are named by DNA extraction code/voucher number, followed by state of collection (two letter abbreviation) and COI haplotype, as reported in
Morphological and molecular data agree in distinguishing multiple species within what has been referred to as E. sordidus. Eurhoptus sordidus itself is restricted to eastern Texas, western Arkansas, and eastern Oklahoma. Sequenced individuals from Arkansas and Texas are strongly supported as monophyletic, and minimally divergent among themselves. A largely more eastern lineage is strongly supported as the sister to E. sordidus, and for this we resurrect
With regard to species not represented by molecular data, we would predict that E. cariniventris would be resolved as the sister to E. pyriformis. Eurhoptus occidentalis from west Texas appears morphologically close to E. sordidus, and would likely fall out somewhere in that clade. Eurhoptus imbricatus and E. rileyi would appear further from these other Nearctic species, and may represent one or more independent lineages with closer relationships to groups known from Mexico and southward. Much broader representation from this largely undescribed Neotropical fauna will be necessary before anything can be said about their relationships.
Eurhoptus
LeConte, 1876: 245;
Europtus
;
Eurrhoptus
Eurhoptus pyriformis LeConte, 1876: 245 (by monotypy). Gender masculine.
(U.S.A. species only). Small, convex, rounded, dull black or dark-brown. Body length (exclusive of head and rostrum) 1.8–3.2 mm, cuticle either largely bare, variously covered with short, fine to coarse, recurved seta-like scales, lacking other scales or variously clothed with dense approximate to imbricate flat scales in addition to recurved seta-like scales. Rostrum short, stout, flattened dorsally, about as long as pronotum or slightly less, scaly towards base, glabrous, finely punctured towards apex in female, more coarsely so in male; medially carinate or not. Eyes small, flat, oval, largely covered by slight post-ocular lobes when rostrum in repose. Head with frons scaly, not impressed. Antennae red-brown, funicle of 7 desmomeres, club small, oval. Pronotum about as wide as long, lateral margins rounded or straight; if straight, then margins tapered more or less evenly from base to apex with greatest width at base; if rounded, then apical portion constricted, tubulate with greatest width before base. Basal margin nearly straight, disc variously punctured, medially carinate, sulcate or evenly punctured; post-ocular lobes slight. Elytra robust, strongly rounded dorsally and laterally, striae distinct, of small to very large punctures; all elytral intervals evenly elevated, slightly rounded, each with single row of recurved seta-like scales. Scutellar shield not visible. Mesoventral cup distinct, metaventrite short, medially impressed behind cup or carinate. Abdomen with ventrite 1 variously modified with large median or paired rather deep pits, pit either glabrous, shining or filled with erect scales; areas around pit often with dense, fine golden setae encircling depression; ventrite 5 broadly triangular, about as long as ventrites 2–4 combined. Legs with femora not toothed, narrow to stout (greatly so in some species where width accentuated by dense, erect scales along dorsal and lateral margins); tibiae narrow to stout (greatly so in some species where width accentuated by dense, erect scales along dorsal and lateral margins); tarsi fine, narrow, article 3 widest, bilobed; tarsal claws minute. Male with aedeagus short, one-half or less length of aedeagal apodemes, in lateral view very slightly curved ventrally to almost straight, in dorsal view with lateral margins subparallel, slightly to abruptly convergent towards apex at about apical one-third to one-fifth. Internal sac with apical sclerite complex of modified cruciform arrangement. Female with bursa copulatrix and vagina lacking any internal sclerotization, spermatheca L-shaped; distal gonocoxite elongate-triangular, with distinct long, slender apical stylus, sternite 8 with apical lamellae short, basally widely divergent, basal apodeme rather robust, elongate, expanded slightly at apex, tergite 8 tapered towards truncate or acuminate finely irregularly serrate apex.
For many years two species have been recorded as occurring in the eastern U.S.A., E. pyriformis and E. sordidus; however, specimens from central Texas of E. sordidus differed in the structure of ventrite 1 with two separate impressions and not a single larger impression thus suggesting a third species was present. This species and two additional undescribed species were noted by
Almost all records of specimens of Eurhoptus are from sifting leaf litter in various forested habitats. Otherwise, nothing is known of life history and immature stages.
Eurhoptus
pyriformis
LeConte, 1876: 245;
Eurhoptus
pyriformis
(part);
This species was described from a single specimen labelled “Ill[inois]”. It has a red square label with “Type 5316” and a handwritten label “Eurhoptus pyriformis Lec.”. It is not dissected but appears to be a male based on the more coarsely punctate rostral apex. The type was not examined although high resolution images posted on the
Body length (exclusive of head and rostrum) 2.1–2.9 mm, cuticle largely bare, variously covered with short, fine recurved seta-like scales, most specimens lacking other scales but some with head and base of rostrum scaly and with a few broad, flat pale imbricate scales variously arranged in irregular oblique band across elytra in apical one-half on intervals 2–7 and at bases of intervals 3–4 and 7. Pronotum with lateral margins straight, margins tapered more or less evenly from base to apex with greatest width at base, not medially carinate but may be medially impunctate in some specimens. Elytra strongly rounded dorsally and laterally, striae distinct, of large punctures, especially in posthumeral region; all elytral intervals evenly elevated, slightly rounded, each with single row of fine recurved seta-like scales. Metaventrite medially deeply impressed behind mesoventral cup. Abdomen with ventrite 1 with large median deep glabrous shining pit, area around pit with dense, fine golden inwardly directed scales encircling depression. Legs with femora and tibiae at most fringed with a few erect scales especially along outer margin of tibiae, hind tibiae subequal in width throughout most of length. Aedeagus about as long as one-half length of aedeagal apodemes, in lateral view slightly ventrally curved, in dorsal view with margins subparallel but abruptly strongly tapered towards apex at about apical one-quarter to one-fifth, apex produced medially as narrow extension, broadly rounded at tip, extension slightly narrower or more acuminate in some (scaly) specimens. Internal sac with large distinct cruciform apical sclerite complex, anterior bars longer than posterior bars, bars well defined, subparallel.
(Figure
Some specimens examined have a few broad, flat pale imbricate scales variously arranged in an irregular oblique band across the elytra in the apical one-half on intervals 2–7 and at bases of intervals 3–4 and 7 (Figures
(293). ALABAMA: Escambia Co.: Brewton, Jct. Hwy 41 & Escambia R. Trib (31.07, -87.06), C.W. O’Brien & P.W. Kovarik, 31 Dec 1997, leaf litter from beech-magnolia forest (1,
Acalles
sordidus
LeConte, 1876: 243;
Eurhoptus
sordidus
(part);
This species was described from a single specimen labelled “Tex”. It has a rectangular label “776” and a red square label with “Type 5268” and a handwritten label “A. sordidus Lec.”. It is not dissected but appears to be a male based on the more coarsely punctate rostral apex. The type was not examined although high resolution images posted on the
Body length (exclusive of head and rostrum) 2.1–2.7 mm, cuticle largely bare, variously covered with short, fine recurved seta-like scales only, although often encrusted and coated with a fine film. Pronotum with lateral margins rounded, margins strongly constricted at about apical one-third such that apical one-third is distinctly tubulate, greatest width at about basal one-third, medially carinate or not. Elytra strongly rounded dorsally and laterally, striae distinct, punctures moderate in size and depth; all elytral intervals evenly elevated, slightly rounded, each with single row of fine recurved seta-like scales. Metaventrite medially impressed behind mesoventral cup. Abdomen with ventrite 1 with pair of obliquely arranged transversely elongate pits which are shallowly continuous medially (but because of encrustation appearing as separate in most specimens), area around pits with dense inwardly directed scales. Legs with femora and tibiae at most fringed with a few erect scales especially along outer margin of tibiae, hind tibiae subequal in width throughout most of length. Aedeagus about as long as one-half length of aedeagal apodemes, in lateral view slightly ventrally curved, in dorsal view with margins subparallel but gradually tapered towards apex at about apical one-third where more strongly tapered, apex not produced medially as narrow extension, broadly rounded at tip. Internal sac with large distinct cruciform apical sclerite complex, with well-defined transverse bar, anterior and posterior bars not well defined.
(Figure
(208). ARKANSAS: Montgomery Co.: 2.42 km. E. Crystal Recreation Area, slopes at FS 177K (34.5, -93.6), C.E. Carlton & H.W. Robison, 19 Jun 1992, (1,
Acalles
curtus
Hamilton, 1893: 308;
Eurhoptus
curtus
;
Eurhoptus
sordidus
;
Eurhoptus
sordidus
(part);
This species was described from Pennsylvania from a series of 4 specimens (
Body length (exclusive of head and rostrum) 1.8–2.8 mm, cuticle largely bare, variously covered with short, fine recurved seta-like scales only, although often encrusted and coated with a fine film. Pronotum with lateral margins rounded, margins constricted at about apical one-third such that apical one-third is tubulate, greatest width at about basal one-third, medially carinate or not. Elytra strongly rounded dorsally and laterally, striae distinct, punctures moderate in size and depth; all elytral intervals evenly elevated, slightly rounded, each with single row of fine recurved seta-like scales. Metaventrite medially impressed behind mesoventral cup. Abdomen with ventrite 1 with pair of obliquely arranged transversely elongate pits which are continuous medially, area around pits with inwardly directed scales. Legs with femora and tibiae at most fringed with a few erect scales especially along outer margin of tibiae, hind tibiae subequal in width throughout most of length. Aedeagus about as long as one-half length of aedeagal apodemes or slightly shorter, in lateral view slightly ventrally curved, in dorsal view with margins very gradually tapered towards apex at about apical one-quarter to one-fifth where abruptly constricted, apex produced medially as broad lobe-like extension, broadly rounded at tip. Internal sac with large distinct cruciform apical sclerite complex, with well-defined posterior bars, anterior and transverse bars not well defined.
(Figure
(219). ALABAMA: Monroe Co.: 1.6 km. S. Claiborne Dam (31.5917, -87.5392), C.E. Carlton, May 31 1995, beech/magnolia riparian berlese (1,
Body length (exclusive of head and rostrum) 2.3–3.0 mm, cuticle almost fully covered with broad, flat scales and scattered short, fine recurved (pronotum) to appressed (elytra) seta-like scales. Pronotum with lateral margins rounded, margins constricted at about apical one-third such that apical one-third is tubulate, greatest width at about basal one-third, not medially carinate; pale scales almost entirely covering pronotum to limited to midline and pair of lateral lines (giving some specimens a trivittate appearance). Elytra strongly rounded dorsally and laterally, striae distinct, of small punctures; all elytral intervals flat, each with single row of fine almost appressed seta-like scales; broad flat scales largely dark brown, approximate, scales pale and imbricate in an irregular oblique band across elytra in apical one-half, at bases of interval 3, at humeri and at elytral apex. Metaventrite medially impressed behind mesoventral cup. Abdomen with ventrite 1 with large median deep shining pit, base of pit with numerous erect, broad pale scales, scales somewhat condensed along midline in anterior portion of pit (giving a divided appearance); area around pit with dense, fine golden inwardly directed scales encircling depression. Legs with femora and tibiae fringed with dense erect scales along outer and inner margins, hind tibiae distinctly wider at about basal one-third. Aedeagus about as long as slightly less than one-half length of aedeagal apodemes, in lateral view slightly ventrally curved, in dorsal view with margins subparallel but gradually rounded towards apex at about apical one-quarter, apex produced medially as slight extension, broadly rounded at tip. Internal sac with apical sclerite complex with well-defined pair of hook-like sclerites.
We name this species “imbricatus” (L., an adjective or participle in the nominative singular, tiled, having adjacent edges overlapping) after the overlapping or imbricate scales of the oblique band on the elytra.
There is some variation in the extent of the distribution of pale scales on the pronotum.
Holotype male (
Body length (exclusive of head and rostrum) 3.2 mm, cuticle almost fully covered with broad, flat scales and scattered short, broad recurved, seta-like scales. Pronotum with lateral margins rounded, margins strongly constricted at about apical one-third such that apical one-third is distinctly tubulate, greatest width at about basal one-third, medially sulcate, median line glabrous, impunctate. Elytra strongly rounded dorsally and laterally, striae distinct, of small punctures; all elytral intervals evenly elevated, slightly rounded, each with single row of broad recurved seta-like scales. Metaventrite medially slightly impressed behind mesoventral cup. Abdomen with ventrite 1 with large median deep glabrous shining pit, area around pit with dense, fine golden inwardly directed scales encircling depression and entering pit along anteriorly along midline such that pit appears somewhat divided. Legs with femora and tibiae fringed with dense erect scales along outer and inner margins, hind tibiae distinctly wider at about midlength. Single specimen likely female, not dissected.
(Figure
We name this species after Edward G. Riley (retired), former collections manager at the Texas A & M University Insect Collection, College Station, Texas. An invariable word in genitive.
Holotype female (
Body length (exclusive of head and rostrum) 1.8–2.7 mm, cuticle largely bare, variously covered with dense, short, fine recurved seta-like scales only. Pronotum with lateral margins rounded, margins constricted at about apical one-third such that apical one-third is tubulate, greatest width at about basal one-third, not medially carinate. Elytra strongly rounded dorsally and laterally, striae distinct, punctures moderate in size and depth; all elytral intervals evenly elevated, slightly rounded, each with single row of dense, fine recurved seta-like scales. Metaventrite medially slightly impressed behind mesoventral cup. Abdomen with ventrite 1 with pair of obliquely arranged transversely elongate pits which are separate medially, and with second pair of small rounded pits along posterior margin of ventrite; ventrite 5 with small pair of central, rounded impressions. Legs with femora and tibiae at most fringed with a few erect scales especially along outer margin of tibiae, hind tibiae subequal in width throughout most of length. Aedeagus about as long as one-half length of aedeagal apodemes, in lateral view slightly ventrally curved, in dorsal view with margins gradually convergent from base to apex, apex not produced, broadly rounded. Internal sac with large distinct apical sclerite complex, with median pyriform sclerite, bordered laterally by pair of apically convergent longitudinal bars these each bordered posteriorly by well-defined transverse pyriform sclerite, longitudinal bars not well-defined.
(Map 2). This species is distributed in west Texas in the Guadalupe and Chisos Mountains. Despite extensive sampling, no specimens are known from New Mexico or Arizona.
We name this species “occidentalis” (L., an adjective or participle in the nominative singular, westerly, connected or coming from the west) after its western Texas distribution.
Holotype male (
Eurhoptus
sordidus
(part);
Body length (exclusive of head and rostrum) 2.2–2.5 mm, cuticle largely bare, variously covered with short, fine recurved seta-like scales only, although often encrusted and coated with a fine film. Pronotum with lateral margins rounded, margins constricted at about apical one-third such that apical one-third is tubulate, greatest width at about basal one-third, medially carinate (most) or not (few). Elytra strongly rounded dorsally and laterally, striae distinct, punctures large in size, deep; all elytral intervals evenly elevated, slightly rounded, each with single row of fine recurved seta-like scales. Metaventrite medially deeply impressed behind mesoventral cup. Abdomen with ventrite 1 with pair of rounded pits which are continuous medially, area around pits with inwardly directed scales. Legs with femora and tibiae at most fringed with a few erect scales especially along outer margin of tibiae, hind tibiae subequal in width throughout most of length. Aedeagus slightly longer than one-half length of aedeagal apodemes, in lateral view very slightly ventrally curved, in dorsal view with margins gradually tapered towards very blunt, truncate apex, apex not produced medially. Internal sac with large distinct apical sclerite complex, with median pyriform sclerite, bordered laterally by pair of inwardly arcuate longitudinal bars these each bordered posteriorly by an elongate oblique sclerite.
(Figure
We name this species ‘aenigmaticus’ (L., an adjective or participle in the nominative singular, enigma, puzzle or riddle) after encountering difficulty in separating it from closely related species of the genus.
Holotype male (
Excluded from type series: ARKANSAS: Marion Co.: 7 mi E County line on Hwy 14 (36.36, -92.8), R. Chenowith, 27 Sep 1977, mixed hardwood litter (1,
Eurhoptus
pyriformis
(part);
Body length (exclusive of head and rostrum) 1.8–2.4 mm, cuticle largely bare, variously covered with short, fine recurved seta-like scales, most specimens lacking other scales but some with head and base of rostrum scaly and with a few broad, flat pale scales variously arranged on elytra in apical one-half and at bases of intervals 2–4. Pronotum with lateral margins straight, margins tapered more or less evenly from base to apex with greatest width at base, medially carinate or not. Elytra strongly rounded dorsally and laterally, almost globular, striae distinct, of very large punctures, especially in posthumeral region; all elytral intervals evenly elevated, slightly rounded, each with single row of fine recurved seta-like scales. Metaventrite medially distinctly carinate behind mesoventral cup. Abdomen with ventrite 1 with large median deep glabrous shining pit, area around pit with dense, fine golden inwardly directed scales encircling depression. Legs with femora and tibiae fringed with erect scales along outer margin of tibiae, hind tibiae subequal in width throughout most of length to slightly wider at basal one-third. Aedeagus about as long as one third length of aedeagal apodemes, in lateral view almost straight, in dorsal view with margins subparallel but strongly tapered towards apex at about midlength, apex produced medially as fine acuminate point. Internal sac with distinct apical sclerite complex of pair of longitudinal parallel bars.
(Figure
We name this species “cariniventris” (L., an adjective or participle in the nominative singular, carina, keeled, and ventris, belly) after the distinctly carinate metaventrite posterior to the mesoventral cup.
This species appears to have two disjunct portions of its range; central Texas and Florida panhandle and adjacent Alabama into eastern Georgia. We know of no specimens from the intervening areas. Specimens from Florida/Alabama have larger, deeper elytral punctures (especially in the posthumeral area) but have similar male genitalia and do not differ in other structural characters. At present, we consider these eastern specimens to be conspecific with the Texas specimens but have excluded them from the type series.
Holotype male (
Excluded from type series: ALABAMA: Dale Co.: Fort Rucker Military Reserve (31.29, -85.72), R. Turnbow, 31 Mar 1993, leaf litter (1,
1 | Body surface almost fully densely covered with broad flat scales, elytra with an irregular oblique band of lighter scales across elytra in apical one-half (Figures |
2 |
– | Body surface lacking broad flat scales, or with a few broad, flat scales arranged in an irregular oblique band across elytra in apical one-half and at bases of intervals 3–5. Legs with tibiae at most fringed with a few erect scales especially along outer margin, hind tibiae subequal in width throughout most of length (except some E. cariniventris which have tibiae fringed along outer margin with dense scales, hind tibia slightly wider at basal one-third) | 3 |
2 | Pronotum with broad, glabrous median line extended from apical one-quarter to base (Figure |
E. rileyi |
– | Pronotum lacking median line or with narrow median glabrous carina of various length (Figure |
E. imbricatus |
3 | Pronotum with lateral margins more or less uniformly convergent from base to apex (e.g. Figure |
4 |
– | Pronotum with lateral margins rounded from apex to base (e.g. Figure |
5 |
4 | Metaventral midline raised and carinate (Figure |
E. cariniventris |
– | Metaventral midline impressed, not raised. Elytra with scales of intervals slightly broader but narrow. Most specimens with elytral punctures slightly larger in area behind humeri but not large and pit-like (Figure |
E. pyriformis |
5 | Abdomen with ventrite 1 with four distinct impressions (2 anteriorly, 2 posteriorly; Figure |
E. occidentalis |
– | Abdomen with ventrite 1 with two distinct impressions (not, or variously confluent medially) | 6 |
6 | Impressions of abdominal ventrite 1 separate (Figure |
E. sordidus |
– | Impressions of abdominal ventrite 1 variously confluent. Pronotum with anterior constriction weak, lateral margins slightly sinuate | 7 |
7 | Aedeagus as in Figures |
E. aenigmaticus |
– | Aedeagus as in Figures |
E. curtus |
We would like to thank the many curators who loaned us specimens: Nico Franz and Sangmi Lee (
Table S1. Full data and GenBank accession numbers for all individuals and genes sequenced