Systematics of Eustylini - Reclassification of the Exophthalmus genus complex (Curculionidae). Poster presented at the 2015 Entomological Society of America Annual Meeting, Minneapolis, Nov 17, 2015

1. 18-0 18-1
16—Rostrum, dorsal surface
(0) plane or medially sulcate, not carinate
(1) medially carinate
17—Rostrum, dorso-lateral angle
(0) smoothly curved, any angulation weak
(1) conspicuously angulate
18—Rostrum, medio-longitudinal sulcus
(0) absent
(1) present
21—Rostrum, dorsolateral fovea
(0) absent
(1) present
28—Rostrum, occipital suture
(0) short, not reaching eye
(1) reaching middle of eye ventrally
16-0 16-1
17-117-0
21-0 21-1
45—Pronotum, surface
(0) smooth or finely rugose
(1) irregularly excavate
29—Rostrum, ventral surface
(0) medially flat, not impressed
(1) medially with triangular impression
79—Elytral vestiture, curled serrate setae
(0) absent
(1) present
79-1
80—Elytral vestiture, series of stripes
(0) absent
(1) present
80-1
60—Metatibial apex, vestiture
(0) ventrally lacking linear, suberect setae
(1) ventrally with sparse, suberect setae
116—Aedeagus, endophallus, sclerites
(0) separate or contiguous, lacking bridge
(1) connected through arched bridge
116-1
119—Aedeagus, endophallus, posterior sclerite
(0) width constant, basally not enlarged
(1) basally enlarged, arched 119-1
48—Pronotum, postocular vibrissae
(0) absent
(1) present
48-1
67—Elytra, apex
(0) not projected, may be acute
(1) distinctly projected
60-1
110—Aedeagus, endophallus, tubular sclerite
(0) absent
(1) present
111—Aedeagus, endophallus, tubular sclerite
(0) not divided into two regions
(1) divided into anterior/posterior region
111-1
24—Rostrum, hypostomal-labial suture
(0) reduced, short, or foveate
(1) long, linear, reaching prementum
29-129-0
24-0 24-1
Figure 5. Core morphological characters (orange color in Fig. 2).
45-145-0
41—Pronotum, disc
(0) convex
(1) flattened
41-141-0
110-1
28-128-0
144—Vestiture, circular glossy metallic scales
(0) absent; if metallic, not circular or glossy
(1) present; often arranged as fasciae or stripes
144-1144-1
67-0 67-1
The New World tribe Eustylini Lacordaire, 1863, pertains to the broad-nosed weevils
(Entiminae) and currently comprises 23 genera. Members of Eustylini include
agriculturally important species, e.g., Diaprepes abbreviatus (Linnaeus, 1758), an
introduced citrus pest in the continental U.S. Franz (2012) published the first phylogeny
of Eustylini based on morphological characters. Eustylini were recovered as polyphyletic
and re-circumscribed to include several genera previously placed in other tribes. As a
result, all but two of the sampled eustyline genera formed a monophyletic clade. The
Exophthalmus genus complex is positioned within that clade and contains eight
sampled genera, the largest (with 95 species) being Exophthalmus Schoenherr, 1823.
The 2012 analysis uncovered systematic problems that motivate the current study.
Exophthalmus remains polyphyletic, with its species separated into at least three
clades. Thus Exophthalmus needs to be redelimited and its current members reassigned
to phylogenetically appropriate generic membership. The clade of continentals species
also contains Rhinospathe Chevrolat, 1878, and Chauliopleurus Champion, 1911,
warranting generic synonymy. Tropirhinus Schoenherr, 1823, Tetrabothynus Labram &
Imhoff, 1852, Compsoricus Franz, 2012, and part of Exophthalmus exhibit ambiguous
boundaries. These groups need to be either re-circumscribed or synonymized.
Systematics of the Exophthalmus genus complex – current status
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5
1. Test and delimit generic boundaries within the Exophthalmus genus complex based on both
morphological and molecular phylogenetic inferences.
2. Revise generic classification within the Exophthalmus genus complex.
3. Redefine the limit of Exophthalmus and reclassify its current constituent species.
Research objectives
Morphological phylogeny. Character matrix (144 characters, examples in Figs 4 & 5) was extracted
and modified from Franz (2012). Thirty-eight species of eight genera in the Exophthalmus genus
complex were sampled, along with 52 species of other eustylines or from other tribes. Phylogenetic
trees were inferred with NONA and character optimizations with WinClada under parsimony.
Molecular phylogeny. Seventy ingroup terminals were included, representing > 65 species and
seven genera. The outgroup contained 105 terminals. Six gene fragments (COI, COII, Ef1-α, Arginine
kinase, 12S, 28S) were sequenced, aligned, and concatenated to generate a 4787 bp data set.
Phylogenetic reconstructions were performed using parsimony in TNT.
Materials & methods
(1) Pachnaeus Schoenherr, 1826
Synapomorphies: Hypostomal-labial suture
long, reaching prementum (24-1, Figs. 2 &
5); postocular vibrissae present (48-1);
anterior endophallic sclerite membranous,
posteriorly tubular (113-1).
Distribution: Cuba & Jamaica.
(2) Tropirhinus Schoenherr, 1823
Taxonomic amendments: Tetrabothynus
Labram & Imhoff, 1852, and Compsoricus
Franz, 2012, placed as junior synonyms.
Exophthalmus species in clade 2 transferred
to Tropirhinus.
Synapomorphies: Pronotal disc flattened or
impressed (41-1); elytral apex projected (67-
1); circular metallic scales forming fasciae
(144-1).
Distribution: Cuba, Hispaniola & Puerto Rico.
(3) Rhinospathe Chevrolat, 1878
Taxonomic amendments: Chauliopleurus
Champion, 1911, placed as junior synonym.
Continental Exophthalmus spp. transferred to
Rhinospathe.
Diagnosis: Rostrum with dorsolateral fovea
(21-1); rostrum ventrally with a short, deep,
triangular impression (29-1).
Distribution: Southern Mexico, Central
America & northern South America.
(4) Diaprepes Schoenherr, 1823
Synapomorphies: Rostrum dorsolaterally
carinate (17-1); occipital suture extends to
middle part of eye (28-1); pronotum
irregularly excavate (45-1).
Distribution: Lesser Antilles & Puerto Rico.
(5) Exophthalmus Schoenherr, 1823
Taxonomic amendments: Exophthalmus re-
circumscribed to refer to a clade containing
its type species E. quadrivittatus (Olivier,
1807). More than 50 species transferred to
other genera.
Synapomorphies: Rostrum dorsally plane,
lacking carina or groove (15-1, 16-0);
Pronotum and elytra with curled, serrate
scales (79-1), arranged into stripes or patches
(80-1).
Distribution: Cuba, Jamaica & Hispaniola.
Figure 1 (left). Proposed new generic classification within the Exophthalmus genus complex, and habitus images of
select species. Five genera are recognized (Figs. 2 & 3). Three are placed in synonymy. Exophthalmus is redefined.
Habitus image (current, unchanged names): (1-3) Pachnaeus spp., Cuba (4) Pachnaeus marmoratus (5) Pachnaeus sp., Jamaica (6) Compsoricus maricao (7)
Exophthalmus humeridens (8) E. regalis (9) E. roseipes (10) E. quindecimpunctatus (11) Tetrabothynus spectabilis (12) Tropirhinus elegans (13) Tropirhinus
nr. lepidus (14) Tropirhinus Cuba GZ48 (15) T. lepidus (16) E. agrestis (17) E. impositus (18) E. jekelianus (19) E. lunaris (20) Exophthalmus Mexico (21)
Exophthalmus nr. annulonotatus (22) E. opulentus (23) Exophthalmus PA[Panama].GZ65 (24) Exophthalmus CR[Costa Rica].GZ147 (25) Exophthalmus
CR.GZ163 (26) E. triangulifer (27) E. verecundus (28) Exophthalmus nr. vermiculatus (29) E. sulcicrus (30) Rhinospathe v-album (31) Diaprepes abbreviatus
(32) D. boxi (33) D. doublierii (34) D. maugei (35) D. rohrii (36) E. cinerascens (37) E. hieroglyphicus (38) E. pictus (39) E. similis (40) E. scalaris (41) E.
quadrivittatus (42) Exophthalmus DR[Dominican Republic] sp. nov. (43) Exophthalmus DR6 (44) Exophthalmus nr. sulphuratus (45) E. vittatus.
Both morphological and molecular phylogenies recover the monophyly of the Exophthalmus genus
complex and the polyphyly of Exophthalmus. They are broadly congruent in five clades, although
the relationships among the clades differ between the two analyses. Five genera can be delimited
within these clades (Fig. 1). Two (Clades 1 & 4 in Figs. 2 & 3) correspond to Pachnaeus and
Diaprepes. Clade 2 contains Tetrabothynus, Tropirhinus, Compsoricus, and Exophthalmus spp.
Tropirhinus is considered the valid name for this clade, hence the other two genera are
synonymized. A large continental clade (3) is obtained, now referred to as Rhinospathe. The genus
Exophthalmus is narrowed to include only West Indian species with a "stripy look" (Figs. 1 & 5).
Future work will focus on increasing species sampling, expanding the character range, combining
morphological and molecular data in phylogeny reconstructions, and describing new species.
Results, taxonomic proposals & conclusions
Figure 2 (above). Morphological phylogeny of the Exophthalmus
genus complex, with character optimizations.
Figure 3 (above). Molecular phylogeny
reconstructed using parsimony.
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Franz N.M. 2012. Phylogenetic reassessment of the Exophthalmus genus complex
(Curculionidae: Entiminae: Eustylini, Geonemini). Zoological Journal of the
Linnean Society 164: 510–557.
This work is supported by the National Science Foundation (DEB-1155984) and the
United States Department of Agriculture (USDA) (Agreement No. 58-1275-1-335).
Dr. Charles W. O'Brien assisted with species identifications. Lin Pan, Will Sides,
Julian Jones, and Joseph Hunter captured habitus or head images.
Reference & acknowledgements
Figure 4 (left).
Morphological diversity of
the rostrum (dorsal view).
Orange numbers denote "core
characters" (see Fig. 5).
Numbers
shown above
branches are
jackknifing
resampling
values.
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