Exophthalmus quadrivittatus (Olivier) 1807

Franz, Nico M., 2010, Redescriptions of critical type species in the Eustylini Lacordaire (Coleoptera: Curculionidae: Entiminae), Journal of Natural History 44 (1 - 2), pp. 41-80 : 61-67

Exophthalmus quadrivittatus (Olivier) 1807 , p 325

( Figures 10–13 )

Description

Male. Length 10.63–19.73 mm, width 3.98–7.72 mm; shape oval to elongate, length/ width ratio 2.52–2.67 (n = 10); greatest width at humeri or near central region of elytra. Setae irregularly arranged, varying from sparse to dense patches appressed to recurvate, white to reddish brown; scales irregularly arranged, absent or forming sparse to dense patches (covering integument), oval, appressed to erect, (orange to) pale yellow to pale-white (iridescent); scales with multiple colours variously interspersed, forming distinct patterns on various regions of surface, typically darker (brownish) dorsally on head, pronotum, and elytra, yet lighter (white to reddish brown) laterally, ventrally, and on legs, scales often partially or entirely absent on worn specimens.

Mouthparts. Mandibles with approximately 12 setae adjacent to scar. Maxillae ( Figure 11A ) with cardo arcuate, apically strongly widened; stipes angulate, apical half directed mesally, apically slightly widened, truncate, lateral margin with one to two setae, apical region with longer setae, transversely strigulate; galeo-lacinial complex extending to midpoint of maxillary palpomere II, mesal margin with five lacinial teeth; palpiger centrally with short setae, apically with transverse row of longer setae; maxillary palpomere I slightly longer than II; II similar in length to III. Labium ( Figure 11B ) with prementum cordate, apical margin truncate, mesally triangularly projected; ventrally with sparsely arranged long setae, each side with obscure row of short setae along lateral margins; labial palpomere III extending to apical margin of prementum; I slightly longer than II; II slightly shorter than III.

Rostrum. Length 1.52–3.54 mm, rostrum/pronotum length ratio 0.68–0.80, rostrum length/width ratio 1.19–1.39. Dorsal outline of rostrum rectangular, dorsolateral margins subparallel, slightly widened at antennal insertion, anteriorly carinate, posteriorly convex. Nasal plate small, slightly projected from anterior region of rostrum, posteriorly with a small carina. Epistoma depressed, glabrous. Dorsal surface of rostrum subplane, rugulose, with two obscure, anteriorly diverging carinae, lacking scales, median sulcus extending from antennal insertion to midpoint between eyes, dorsolateral sulci absent; ventrolateral margins emarginate, centrally constricted. Rostrum in lateral view apically strongly expanded; ventrolateral sulci present. Antennal insertion near anterior third. Scrobe arcuate, extending to anterior margin of eye, glabrous.

Antennae with scape extending to posterior margin of eye, ventrad of eye (in idealized position) through region ventrad of eye, covered exclusively with setae. Funicle similar in length to scape; funicular antennomeres progressing from elongate to equilateral, and from clavate to cylindrical; II slightly shorter than I. Club similar in length to funicular antennomeres IV–VII, nearly three times longer than width, dark brown; I and II similar in length, III and IV each slightly shorter.

Eyes separated from anterolateral margin of pronotum by distance similar to horizontal diameter of eye, interocular distance similar to maximum width of eye; with nearly 40 facets along maximum diameter.

Head rugulose above posterodorsal margin of each eye, occiput densely strigulate.

Thorax. Pronotum equilateral to transverse, length/width ratio 0.79–0.89, pronotum/elytra length ratio 0.29–0.32; dorsal surface punctate, rugulose; scales evenly appressed, with two subparallel, slightly irregular stripes consisting of white scales and extending on each side along posterior two-thirds of pronotum, slightly interrupted near midpoint; median sulcus with posterior quarter expanded into triangular, concave region. Anterodorsal margin nearly two-thirds length of posterodorsal margin; dorsolateral margins anteriorly converging, posteriorly either slightly converging or diverging; posterolateral edges projected; posterior margin slightly bisinuate, with one small projection on each side of median sulcus. Pronotum in lateral view subquadrate to conical, with one irregular impression above procoxal cavity and with two to four irregular regions of scales similar to those of pronotum: one in dorsolateral region and one in ventrolateral region; anterolateral margin nearly straight, without postocular lobe, yet with one small region of scales along portion of margin corresponding to ventral half of eye, postocular vibrissae absent. Metascutum with short, fine setae. Scutellum subcircular, glabrous. Mesepimeron with one region of scales extending obliquely from posterior edge.

Prosternum nearly 1.5 times as long as mesosternum. Mesosternum nearly twothirds length of metasternum, anterior half covered with elliptical, plumose-scopiform scales, intercoxal process covered with white scales, posteromesal edge setose. Metasternum with median sulcus extending along posterior third, with white scales between metacoxal cavities; metacoxal cavities separated by distance nearly 3/5 the width of each mesocoxal cavity. Metendosternite as in Figure 11C .

Legs. Prothoracic legs distinctly longer than mesothoracic legs. Procoxa with most proximal scales plumose. Profemur/pronotum length ratio 1.39–1.57; straight, in cross-section elliptical. Protibia/profemur length ratio 1.08–1.14; protibia very slender, in cross-section elliptical; ventral margin with several rows of (very) long, aurate setae; and with row of 10–15 cuticular teeth; protibial apex with mucro shorter than tarsal claw, surpassed by 2–3 groups of reddish brown setae. Protarsus with tarsomere I equilateral to elongate; tarsomere II transverse. Mesofemur and mesotibia shorter than metafemur and metatibia, respectively. Metatibial apex with anterior margin slightly arcuate; surface surrounding tarsal condyle glabrous.

Elytra. Length/width ratio 1.80–1.92; greatest width at humeri or near central region. Anterior margins jointly wider than posterior margin of pronotum, each anterior margin distinctly projected along mesal half, yet indistinct along lateral half, strongly sinuate; lateral margins subparallel along anterior half, gradually arcuately converging along posterior half; posterior margins acutely projected. Elytra with nine complete striae and one incomplete elytral stria; strial width variable; stria X merging with stria IX near anterior third; punctures narrowly separated by distance shorter than width of each puncture; intervals subplane, intervals I–III more widely spaced than intervals IV–X, intervals III/IV and VIII/IX covered with white scales similar to those of pronotum, yet interspersed with similarly dense and narrower, erect, longitudinally plicate, yellow scales (which are responsible for the characteristic yellow stripes), stripes merging at declivity, stripe of interval III/IV partially or entirely interrupted near anterior third.

Wings ( Figure 11D ) with wing/body length ratio 1.14–1.22; length/width ratio 3.30–3.43 (n = 4).

Abdomen. Ventral sterna III and IV superficially connected, V–VII separate; III centrally subplane, laterally slightly convex; suture separating III + IV shallow, slightly arcuate; V and VI jointly similar in length to IV; lateral regions of ventral sterna covered with white scales, III with narrower line of scales on anterior projection, VII with scales limited to anterior half. Pygidium trapezoidal; posterior margin slightly arcuate, mesally deeply and widely emarginate, ventrally plicate.

Terminalia. Sternum VIII ( Figure 12A ) consisting of two pyriform to triangular sclerites; each sclerite mesally with one acute projection, posterior margin with three to five longer setae. Spiculum gastrale ( Figure 12B ) similar in length to median lobe; posteriorly bifurcate (Y-shaped), furcal arms elongate, slightly arcuate, posteriorly slightly diverging; each arm with one small, nodular projection on lateral margin. Tegmen ( Figure 12C ) nearly 3/5 length of median lobe. Aedeagus ( Figure 12D ) with median lobe length/width ratio 5.32–5.66 (n = 4); lateral margins subparallel along most of length, anterior one-sixth slightly expanded (alate); apex narrowly rotundate. Median lobe in lateral view sinuate, anteriorly deflexed, posteriorly slightly reflexed; width slightly narrowed towards apex; apex explanate, slightly reflexed. Internal sac with one centrally positioned, subdivided, tubular sclerite, anterior region consisting of two larger, semi-tubular sclerites, posterior region with one narrower tubular sclerite, anteriorly expanded into recurvate laminate projection terminating in a transverse tumescence, posteriorly slightly angulate. Adeagal apodemes nearly half as long as median lobe.

Female ( Figure 10A–F ). Length 12.73–19.47 mm, width 4.75–7.39 mm; length/width ratio 2.41–2.67 (n = 10); greatest width at humeri or near central region of elytra. Rostrum length 1.94–3.20 mm, rostrum/pronotum length ratio 0.77–0.83, rostrum length/width ratio 1.29–1.35. Pronotum length/width ratio 0.73–0.87; pronotum/ elytra length ratio 0.24–0.30; greatest width near central region or at posterior margin. Metasternum concave in posterior 1/2, median sulcus posteriorly deepened into a distinct fovea. Protibia/profemur length ratio 1.08–1.18. Elytra length/width ratio 1.84–2.04; posterior declivity slightly angulate, outline slightly arcuate. Venter with sterna III and IV centrally subplane, laterally slightly convex; VII triangular, posterior margin narrowly arcuate. Pygidium subtriangular, posterior margin arcuate, ventrally slightly plicate, yet not emarginate.

Terminalia. Tergum VII posteriorly with longer unifid setae. Sternum VIII ( Figure 13A ) with anterior three-fifths stylate; posterior two-fifths triangular, spatulate, medially fused (not bifurcate); each arm with plicae subcontiguous along posterior half, posteriorly longer, densely arranged setae. Coxites and styli as in Figure 13B . Genital chamber nearly half as long as sternum VIII. Spermatheca ( Figure 13C ) V-shaped; ramus short, nearly contiguous with collum (corpus short); collum relatively long and projecting perpendicular to corpus; cornu (apical half) nearly straight, apex narrowly acute, slightly deflected.

Variation

The examined material varies primarily in size and in continuity and extension of the lateral stripes of white scales on the pronotum and the stripes of yellow scales corresponding to strial interval III/IV. Individuals in some populations have orange to reddish scales on the pronotum and elytra.

Specimens examined

“ Dominican Republic, La Altag. [La Altragracia], 9 km SW. Campo Nuevo, August 1, 1979, G.B. Marshall” (two males and two females, CWOB). Other conspecific material seen from the La Romana and San Cristóbal Provinces, Dominican Republic (housed at UPRM) .

Figures

Figure 10. Habitus of Exophthalmus quadrivittatus, female; (A) dorsal view; (B) lateral view; (C) ventral view; (D) head, dorsal view; (E) head, lateral view; (F) metatibia, lateral view.

Figure 11. Mouthparts and thoracic structures of Exophthalmus quadrivittatus. (A) Right maxilla, ventral view; (B) labial prementum, ventral view; (C) metendosternite, posterior view; (D) right wing.

Figure 12. Terminalia of Exophthalmus quadrivittatus, male. (A) Sternum VIII, ventral view; (B) spiculum gastrale, ventral view; (C) tegmen, ventral view; (D) aedeagus, ventral view and lateral view.

Figure 13. Terminalia of Exophthalmus quadrivittatus, female. (A) Sternum VIII, ventral view; (B) posterior region of coxites and styli, ventral view; (C) spermatheca.