Epicaerus panamensis Girón & de Medeiros, 2022

Atencio, Randy, Barba, Anovel, Collantes, Rubén, Pittí, Javier, Muñoz, Jorge, De Medeiros, Bruno A. S. & Girón, Jennifer, 2022, A new species of Epicaerus Pascoe, 1881 (Coleoptera: Curculionidae: Entiminae: Geonemini) associated with potato cultivars in Tierras Altas de Chiriquí, Panama, Zootaxa 5115 (1), pp. 103-121 : 106-114

Epicaerus panamensis Girón & de Medeiros n. sp.

Type material. Holotype (male): PANAMA: Chiriquí Province, Tierras Altas de Chiriquí District , Cerro Punta , 8.854, -82.573, 1952 m a.s.l., 30.XI–1.XII.2020, J. Pitti & R. Collantes ( MIUP).

Paratypes. (71 specimens). PANAMA: Same data as holotype (18 ♂, 3 dissected; 20 ♀, 3 dissected [including STRI_ENT_132115, STRI_ENT_132116, STRI_ENT_132119, STRI_ENT_132120]). Same data except 19.IV.2021, J. Pitti (14 ♂, 17♀, [including STRI_ENT_132117, STRI_ENT_132118, STRI_ENT_132121, STRI_ ENT_132122]).). Same data except Las Nubes, 8.8719, -82.5917, 1882 m a.s.l., 21-X-2020. Leg. Jorge Muñoz. Chiriquí, 3 km W Cerro Punta, 8°51’N, 82°36’W, 1720 m, 2 Aug 79 ( ASUCOB0019951 , ASUCOB0019955) .

Additional specimens. (20 specimens) PANAMA: Chiriquí Province, 3 km W Cerro Punta , 1750 m., 28.VII.1996, H. P. Stockwell (1♂, 1 ♀ MIUP; 6♂, 6 ♀ STRI); same, except 8º51’N, 82º36’W, 1720 m., 21.VII.1982 (1 ♀ STRI); same but 26.V.1977 (3 ♀ STRI); same, except 10.V.1976 (2♂ STRI). These additional specimens were previously identified as Epicaerus inaequalis in collections and are not included in the type series since they correspond to older collecting events .

Differential diagnosis. Epicaerus panamensis can be recognized by the following character combination: oval to teardrop-shaped eyes in lateral view ( Fig. 3B, E ); rostrum anteriorly broadened, with epistomal area depressed, and with dorsolateral sulci ( Fig. 4 ); antennal scrobes visible dorsally only at apical region of rostrum; antennal scape covered by non-overlapping, seta-like scales ( Fig. 4 ); pronotum medially broadly depressed, with two deep and broad foveae, each positioned at basal and apical thirds along midline ( Fig. 3A, D ); humeri strongly reduced, with anterolateral corner of each elytron (humeral angle) slightly produced anterior and laterally ( Fig 3D ); joint anterior margins of elytra straight to nearly concave ( Fig. 3A, D ); scutellar shield absent, scutellar area of the elytra depressed, covered by pale scales ( Fig. 3A, D ); elytra moderately and uniformly convex in lateral view, in dorsal view with lateral margins uniformly convex; scale coverage relatively uniform in density, composed of small scales ranging in coloration from pink to yellow to brown and black, not forming evident patterns.

There are several species of Epicaerus of similar size and overall appearance, with anteriorly broadened and medially depressed rostrum, medially depressed and coarsely punctate pronotum, strongly reduced humeri that are slightly produced anterior and laterally, and sharing the presence of a patch of pale scales on the scutellar area of the elytra ( Fig. 3A, D ). Epicaerus panamensis n. sp. can be differentiated from similar species by the alignment and moderate depth of the elytral punctation, the elytra moderately and uniformly convex in lateral view, and the relatively uniform pinkish tone of the scales.

Epicaerus panamensis also resembles species of the South American genus Exorides Pascoe, 1881 ( Pascoe 1881, p. 43; Marshall 1922; Wibmer & O’Brien 1986) by virtue of several characters that are typical of some members of the tribe Eustylini Lacordaire, 1863 ( Lacordaire 1863, p. 205): teardrop-shaped eyes in lateral view ( Fig. 3B, E ); rostrum anteriorly broadened; pronotum medially depressed ( Fig. 3A, D ); elytra with humeri strongly reduced to absent. The absence of scutellar shield in Epicaerus panamensis easily distinguishes it from similar members of Exorides .

Description. Body length 12–14 mm (females), 10–13 mm (males), width 5–6 mm (females), 4–5 mm (males); shape oval, length/width ratio 2.3–2.8; greatest width near mid-length of elytra both in males ( Fig. 3A ) and females ( Fig. 3D ). Integument dark brown to black; coverage composed of non-overlapping scales, denser along sides and depressed areas of pronotum and elytra ( Fig. 3 ); scales oval, small, appressed, iridescent with pink and blue tones, or light to dark brown ( Fig. 3 ).

Head. Frons with somewhat uneven surface, slightly transversely impressed behind eyes, bearing deep, large median fovea and a pair of slight depressions, covered by oval to setiform setae, between midlength and base of rostrum and midway to medial longitudinal line ( Fig. 4A , white arrow); surface of head sparsely covered by scales; curved, thick, pale brown setae scattered only along dorsal surface of head. Eyes in lateral view ( Fig. 3B, E ) oval, slightly tear-drop shaped, 1.3 × longer than wide, with acute margin pointing antero-ventrally; eyes somewhat dorso-lateral, separated from anterolateral margin of prothorax by distance slightly shorter than greatest width of eye; surface surrounding anterior margin of eye moderately impressed; surface surrounding dorsal margin of eye forming well-defined ocular sclerite; in dorsal view ( Fig. 4B ), eyes moderately convex, with inner margins oblique, anteriorly converging, interocular distance at closest point, 4.0 to 4.5 × maximum width of eye.

Rostrum. Only very slightly longer than wide ( Fig. 4B ), anteriorly widened apicad of antennal insertion; shape in cross-section subrectangular. In dorsal view ( Fig. 4B ), outline of rostrum somewhat trapezoid, 1.3 × wider near apex than at base; dorsolateral margins slightly sinuate; dorsal surface undulate; apical margin deeply emarginate ( Fig. 4A ). Nasal plate ( Fig. 4A ; see Vaurie 1963, Girón & Howden 2019) moderate in size, with depressed and smooth surface, positioned obliquely to surface of epistoma, with posterior margin rather sharply creased. Epistoma ( Fig. 4A ) distinctly depressed, with small, oval scales scantily scattered across surface; posterior margin of epistoma elevated. Epistomal setae ( Fig. 4A ) golden in color, moderate in thickness, length, and density, apicomedially pointing. Area of epistoma between posterior margin of nasal plate and epistomal setae flat, glabrous and nearly parallel to dorsal surface of rostrum. Dorsal surface of rostrum with one deep, anteriorly broadly widened median sulcus ( Fig. 4 ) forming large, elongate triangular depression, extending between posterior margin of epistoma and base of rostrum, continuing more shallowly towards median frontal fovea; with two short dorsolateral sulci ( Fig. 4A ) positioned along nearly midlength of rostrum; lateroventral margins ( Fig. 4A ) anteriorly diverging. Ventral margin of antennal scrobe, nearly fully visible in dorsal view of rostrum. Rostrum in lateral view ( Fig. 3B, E ) slightly and gradually expanded apically, with dorsal outline slightly convex along median third; occipital suture deep extending from anteroventral margin of eye to ventral posterior third of rostrum to meet anterior tentorial pit, continuing anteriorly to near apex of rostrum; gular sutures basally fused together medially, separating at base of rostrum, not extending to posterior tentorial pits. Antennal insertion near anterior third of rostrum. Scrobe lateral ( Fig. 3B, E ), arcuate, deep, and broad, gradually expanding towards midlength of rostrum, with margins continuing nearly parallel towards ventral region of rostrum, with dorsal margin well-defined throughout, ending near ventral third of anterior margin of eye; ventral margin of scrobe ending at basal third of rostrum; scrobe covered with setae and elongated scales along posterodorsal areas.

Mandibles shiny and lacking scales; each mandible with setae on outer and ventral surfaces; mandibular scar only slightly raised from surface ( Fig. 4A ). Maxillae not visible along sides of prementum; prementum trapezoid, only slightly expanded towards apex 1.1–1.2 × longer than greatest width near apex, with ventral surface reticulate and undulate, bearing long fine setae on apical corners.

Antennae with 12 antennomeres ( Fig. 4 ). Scape clavate, widened along apical third, extending to posterior margin of eye, passing over ventral fifth of eye (in resting position), covered with elongate scales, with sparse, thick, semi-erect setae. Funicle about 1.3 × longer than scape, with seven antennomeres; funicular antennomeres clavate, all similar in shape and size, except funicular antennomere 2 slightly longer. Club with four distinct visible antennomeres (terminal annulation fully differentiated, see Fig. 4A ), nearly as long as funicular antennomeres 5–7 combined, nearly 2 × longer than wide, densely covered by fine setae; club antennomeres gradually decreasing in length towards apex.

Thorax. Pronotum somewhat trapezoid ( Fig. 3A, D ), 1.5 × wider at base than at apex, slightly longer than basal width; pronotum nearly 0.4–0.5 × length of elytra, with greatest width at base; lateral outline nearly parallel along basal two thirds, converging along apical third; posterior margin straight in females, slightly medially emarginate in males. Dorsal surface of pronotum undulate-foveate, medially longitudinally and broadly depressed, with two deep and broad foveae each positioned at basal and apical thirds along midline; lateral surfaces irregularly foveate; scales appressed, ranging from evenly distributed to covering only depressed areas; median area of pronotum often posteriorly depressed. Prothorax in lateral view ( Fig. 3B, E ) somewhat trapezoid (shorter ventrally); anterior margin oblique, only slightly curved, without postocular lobe, fringed with plumose setae projecting anteriorly; postocular vibrissae absent. Scutellar shield not visible externally. Prosternum ( Fig. 3C, F ) slightly longer than mesoventrite, mesoventrite similar in length to metaventrite; prosternum with transverse posterior sulcus and anteriorly with shallow lateral sulci; procoxal cavities contiguous, 3 × closer to anterior than to posterior margin of prosternum; anterior margin of prosternum fringed mostly by plumose setae. Mesoventrite ( Fig. 3C, F ) with intercoxal process slightly elevated, covered by oval scales; mesocoxal cavities separated by distance nearly 0.2–0.3 × greatest width of each mesocoxal cavity. Metaventrite ( Fig. 3C, F ) with median sulcus very short, shallow, Y-shaped, positioned near posterior margin; metacoxal cavities separated by distance nearly 0.7 × width of each mesocoxal cavity.

Legs. Prothoracic legs slightly longer than mesothoracic legs, slightly shorter than metathoracic legs; densely covered by scales with color similar to elytra and with evenly spaced whitish to pale brown, recurvate setae along femora, denser along tibiae, especially along antero-ventral margin. Profemur about as long as prothorax, gradually enlarging to slightly apicad of midlength, with ventral margin basally straight, distally strongly bisinuate; unarmed. Protibia about as long as profemur, slender, distally slightly expanded, with ventral margin slightly arcuate, especially along distal fourth; ventral margin without cuticular teeth, with row of translucent to pale brown spiniform setae; protibial apex with anterior margin slightly arcuate, densely fringed by fine setae; mucro shorter than to similar in length to tarsal claw, surpassed by tuft of fine, long setae. Protarsomeres 1 and 3 similar in length, protarsomere 2 0.6 × length of protarsomere 1; protarsomere 5 slightly longer than 3. Mesofemur slightly longer than mesotibia, similar to prothoracic legs; mesotarsomeres about same proportions as protarsomeres. Metafemur gradually enlarging towards second third, slightly longer than metatibia. Metatibia straight, expanded at apical region; metatibial apex with anterior margin obliquely truncate, posteriorly ascending by one third of apical width; setal comb with setae similar in length along apex, longer along ascending region; articular surface (surrounding tarsal condyle) glabrous; both inner flange and outer bevel fringed by row of spines (“corbel enclosed”); outer bevel very narrow and lacking scales. Tarsal claws paired, separate, simple.

Elytra. ( Fig. 3A, B, D, E ) 1.4–1.5 × longer than greatest width; greatest width near midlength in both males and females; joint anterior margins only slightly wider than posterior margin of pronotum; humeri strongly reduced, anterolateral corner of each elytron slightly produced anterior and laterally ( Fig 3D ); surface of each elytron broadly and rather shallowly depressed around basimedial margin, densely covered by scales, with distinct patch of pale yellowish to pale pink scales; outline of each elytron in dorsal view straight and slightly diverging along anterior half, then evenly curved and gradually converging along posterior third. Elytra in lateral view ( Fig. 3B, E ) with dorsal outline nearly straight along anterior half, then evenly and strongly convex; summit of elytral declivity ( Cortés-Hernández & Morrone 2020, fig. 3D) evenly curved in males, slightly angulate in females. Posterior margin of each elytron only slightly rounded, forming slightly obtuse angle ( Fig. 4B ). Elytra with longitudinally aligned punctures forming ten complete striae; striae 9 and 10 coming closer along metacoxal insertion, but fully separated along entire length; interstriae convex along most of their length, but not forming costae ( Fig. 4B ); interstriae 10 slightly convex at level of metaventrite; setae slightly shorter than width of intervals, recurvate, evenly distributed along interstriae, and sometimes between punctures in striae, slightly denser along lateral margins and elytral apex; scales covering entire integument, oval, overlapping, varying from whitish to brown or iridescent pink; distribution of scale colors variable across specimens.

Hind wings absent.

Abdomen. Abdominal ventrites ( Fig. 3C, F ) moderately covered with scales; ventrite 1 slightly longer than thoracic metaventrite, with posterior margin sinuate; abdominal ventrite 2 slightly shorter than 1, nearly as long as 5; surface of intercoxal process of ventrite 1 moderately depressed; surface of ventrites 1 and 2 laterally bulging, medially nearly flat in males ( Fig. 3E ), convex in females ( Fig. 3C ); ventrite 5 1.7 × wider than long, with broadly rounded apex in males ( Fig. 3F ), 1.5 × wider than long, with slightly emarginate apex in females ( Fig. 3C ).

Male terminalia. Tergite 8 about 1.2 × as wide as 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 uniformly and evenly curved. Sternite 8 ( Fig. 5A ) composed of two lateral hemisternites somewhat weakly sclerotized, joined medially by membrane, somewhat sigmoidal in shape, laterally narrow, with few, long, apical setae. Sternum 9 (spiculum gastrale; Fig. 5A ) including apodeme, about as long as median lobe, posteriorly bifurcate, furcal arms opposed; each furcal arm with sigmoidal outer margin, broadened and coarsely punctate medially, with somewhat triangular distal region more strongly sclerotized, rounded at apex. Tegmen ( Fig. 5B ; gonocoxites I, Boudinot 2018) with apodeme 0.6 × length of median lobe; tegminal plate with two elongate projections ( Fig. 5B, B 1 ), each nearly 0.3 × length of apodeme, finely and densely denticulate along distal half. Aedeagus with median lobe ( Fig. 5C ; penial sclerite, Boudinot 2018) strongly melanized, 6 × longer than widest point (at base) in dorsal view, with medial longitudinal region lightly sclerotized and somewhat creased; surface of aedeagus irregular, softly undulate; basi-ventral margin broadly emarginate; lateral margins nearly straight, gradually converging towards apex; apical region of median lobe gradually and evenly narrowing distally, ending in narrowly rounded tip, with yellowish setae along margins ( Fig. 5C–E ); distance from apical margin of ostium (gonopore) to apex of median lobe slightly longer than greatest length of ostium ( Fig. 5D ); median lobe in lateral view ( Fig. 5E ) broadly curved by about 120° near basal third, approximately 6.3 × longer than greatest width (at base of ostium), gradually widening from base to base of ostium, then dorsal margin tapering towards apex; apex slightly bent downwards. Endophallus only visible at ostium, with a pair of apically rounded medial endophallites ( Fig. 5D ; Génier 2019). Aedeagal apodemes (gonocoxites II, Boudinot 2018) 0.8 × length of median lobe, gradually narrowing towards median lobe, broadly curved along apical half, fused to median lobe.

Female terminalia. Tergite 8 greatest length 1.2 × longer than greatest width, with anterior margin mesally broadly and deeply emarginate; surface coarsely and sparsely punctate near apex, each puncture bearing one seta; with short row of long and thick setae on either side near apex; setae shorter along apical margin. Sternite 8 ( Fig. 6A, B ) with apodeme nearly 1.6 × longer than lamina; lamina triangular, apically narrowly rounded, 2 × longer than wide, apical third with row of setae near margins, gradually denser towards apex; basi-medial region of lamina with paired sclerotized longitudinal bars; lateral areas of lamina bent upwards ( Fig. 6A, B ). Coxites strongly compressed laterally, nearly 1.3 × longer than lamina of sternum 8; distal coxites ( Fig 6C , dcx) separated from proximal coxites ( Fig 6C , pcx) by less sclerotized area; apical margin of coxites in lateral view sinuate, with dorsal section ( Fig. 6C, E ds) larger and wider than ventral section ( Fig. 6C, E vs); ventral section of distal coxites with scarce and thick setae; styli ( Fig. 6C, E , sty) short, tubular, 2.7 × longer than wide, apically with stout setae; styli inserted on dorsal lobe of coxites. Genital chamber with a large and strongly sclerotized, bident-shaped distal sclerite, with tips pointing posteriorly ( Fig. 6C , dscl) and a pair of small, oval, lateral proximal sclerotizations ( Fig. 6C , pscl) basad of coxites. Membranes of bursa copulatrix finely papillate ( Fig. 6C , bc). Spermatheca ( Fig. 6C , spe; 6D) hook-shaped; ramus ( Fig. 6D , ra) and collum ( Fig. 6D , cl) similar in length, both apically truncate; ramus slightly wider than collum; corpus ( Fig. 6D , crp) slightly longer and nearly 2.8 × wider than cornu ( Fig. 6D , cn); cornu forming a curved, nearly straight angle with outline of corpus, apically rather broad and irregular.

Variation. The color and density of the scales vary between specimens. In some specimens, particularly on the elytra, dark brown scales very similar in color to the integument may be dominant, while in others pink or yellowish scales are more common. Moreover, in some specimens, loosely defined transversal bands of yellowish to brown scales may be observed along the posterior third of the elytra and, less commonly, along the anterior third. While a patch of pale scales is always present around the scutellar area of the elytra, the color of these scales varies from white to yellowish or pink. The medial depression on the pronotum may be not as distinct in some specimens, but the two deep foveae along the longitudinal midline are always present.

Distribution. Specimens of Epicaerus panamensis n. sp. have been collected at the localities of Tierras Altas and Las Nubes, and near Cerro Punta, Chiriquí Province, Panama, between 1720 and 1952 m in elevation.

Etymology. The species is named after Panama, the country where the species has been found.

Natural history. The specimens have been found on the foliage of potato (Solanum tuberosum L., Solanaceae), sweet potato (Ipomoea batatas (L.) Lam., Convolvulaceae), golden berry (Physalis peruviana L., Solanaceae), forage peanut (Arachis pintoi Krapov. & W.C.Greg., Fabaceae), and barley (Hordeum vulgare L., Poaceae). Studies on reproduction habits, location of eggs, larvae and pupae are necessary in the future to understand the population dynamics of the species, especially given its potential economic importance.

Figures

FIGURE 1. Weevil specimens and damage in the field at Tierras Altas de Chiriquí, Panamá: A. Individuals on vegetation. B. Mating couple on vegetation. C. Damage on potato leaves. Photos by Javier Pitti.

FIGURE 3. Habitus of Epicaerus panamensis: A–C female, D–F male. A, D dorsal view, B, E lateral view; C, F ventral view. Scale bars: 2 mm.

FIGURE 4. Head and posterior view of Epicaerus panamensis: A head, dorsal view, white arrow pointing lateral depression on rostrum; B posterior view.

FIGURE 5. Male genitalia of Epicaerus panamensis: A spiculum gastrale, B tegmen, B1 detail of projections of tegminal plate, C aedeagus, dorsal view, D apical region of aedeagus, E aedeagus, lateral view; as: apical setae; ep: endophallite.

FIGURE 6. Female genitalia of Epicaerus panamensis: A–B abdominal sternite 8 (apo: apodeme; lam: lamina), A ventral view, B lateral view, C ovipositor (sty: stylus; ds: dorsal section of distal coxites; dcx: distal coxites; small triangle marks separation between proximal and distal coxites; pcx: proximal coxites; vs: ventral section of distal coxites; dscl: distal sclerite; pscl: proximal sclerites; bc: bursa copulatrix; spe: spermatheca) D spermatheca (ra: ramus; cl: collum; crp: corpus; cn: cornu), E detail of apex of coxites including stylus (sty: stylus; ds: dorsal section of distal coxites; vs: ventral section of distal coxites).