Stethobaroides Champion, 1908

Prena, Jens, 2025, Neotropical orchid-weevils of the genus Stethobaroides Champion (Coleoptera, Curculionidae, Baridinae), Zootaxa 5723 (2), pp. 227-244 : 228-231

Stethobaroides Champion, 1908

Type species. Stethobaroides nudiventris Champion , by original designation.

Redescription. The original description of the genus ( Champion 1908, p. 399) is modified as follows, with my additions underlined: Mandibles decussate; rostrum arcuate, moderately long, antennae inserted at or slightly behind middle, club acuminate-ovate; prothorax transverse, subconical, abruptly constricted and tubulate in front, feebly bisinuate at base, median lobe emarginate; scutellum free, oblong, narrow, parallel-sided; elytra rounded-triangular, with obliquely truncated humeri, leaving upper portion of mesothoracic epimera exposed, sharply crenate-striate, separately rounded at apex, interstrial sulci absent; pygidium exposed, transverse, subvertical, sexually dimorphic; prosternum deeply sulcate, sulcus widening to anterior coxae, then narrowed and margined between them, basal process short; anterior coxae separated by about one half, intermediate and posterior coxae by nearly twice, their own width; mesosternum depressed, exposed, connate with metasternum; ventral segments 1 and 2 connate in their median third; femora sublinear, unarmed; tibiae strongly unguiculate; tarsal claws minute, narrowly separated; body subrhomboidal to ovate, moderately arched, glabrous above (one species with microscopic setae).

The following gender-specific traits apply: Male with rostrum stout, antenna inserted at mid-length; sternite 7 with two rows of plectra for stridulation ( Fig. 3 ), sternite 8 with distal 2/3 protruding beyond elytral apices, last ventrite with setose median depression and with apical margin gently sinuous, basal ventrites depressed; penis elongate and of moderate size, endophallic sclerites absent, tegmen with apodeme wide and short ( Figs. 4 , 5 ); female slightly more elongate than male, with rostrum longer, slenderer and antenna more basally; exposed part of pygidium formed by short sloping apical portion of sternite 7, last ventrite without median depression but frequently with divergent sculpture and distal margin ( Fig. 6 ), basal ventrites convex; spermathecal duct as long as bursa, inserted ventrally near base of bursa, sternum 8 distally with even row of notably long setae ( Fig. 7 ).

Diagnosis. The known species are 2.3–4.1 mm long and, as noted by Champion (1908), resemble species of the genus Stethobaris (including the doubtfully distinct Cerpheres , Diorymerellus , Lasiobaris , Ovanius and Montella ). Stethobaroides differs from Stethobaris by the exposed, sexually dimorphic pygidium, separately rounded elytral apices and the absence of interstrial sulci in males ( Prena & O’Brien 2011). The sinuous distal margin of the last ventrite of females ( Fig. 6 ) is also diagnostic. Miniaturization of the male genitalia, common in Stethobaris ( Prena & O’Brien 2011) , does not occur in Stethobaroides . Other differences mentioned by Champion (1908) and Casey (1922), such as the distance between the procoxae, the shape of the scutellum, the anteriorly protruded elytral margin and the length of the antennal club, do not hold for all included species. Numerous other genera have superficially similar species but these have longer claws or a covered pygidium and most lack a subtriangular prosternal depression.

Distribution. The genus is known from México, Central America (not including West Indies), Colombia, Ecuador and the Atlantic lowlands of South America south to southern Brazil. Most records are from low elevations, the highest is from nearly 2000 m at Jericó in Antioquia, Colombia (J. Cardona Duque, personal information).

Life history. Plant associations are available for all Stethobaroides species except the three large ones from the Mexican Pacific regions. Adult weevils occurred particularly on flowering orchids of the subtribes Catasetinae and Stanhopeinae in Cymbidieae, subfamily Epidendroideae ( Hentrich 2003, Morales Báez et al. 2016, Córdova Ballona & Sánchez Soto 2022, Garlet et al. 2025; M. Amador, E. Baron, J. Cardona Duque, H. Hespenheide, K. Nishida, G. Quintos Andrade, Y. Sageth Ruiz, P. Sanz Veiga, H. Stockwell, all unpublished observations). Adult weevils of one species occurred numerously on Vanilla planifolia Andrews in Costa Rica (see under S. permixtus ). Fonseca (1957) reported associations with Cattleya Lindl. and Laelia Lindl., and Rivera Coto & Corrales Moreira (2007) with another ten genera of various epidendroid tribes, mostly Laeliinae. The records of these two latter works need verification because of possible confusion with species of Stethobaris . Larvae of S. nudiventris , S. scutellatus and an unidentified species from El Salvador develop in the flower ( Morales Báez et al. 2016; P. Sanz Veiga and Y. Sageth Ruiz, personal information). The complete life cycle has been explored in detail only for S. scutellatus in the states of São Paulo and Pará, Brazil (P. Sanz Veiga, personal information) and will be documented in a separate paper. Published life history data may not always be accurate because up to three species of Stethobaroides and Stethobaris found together on the same plant had been included in the series examined by me.

Figures

FIGURE 3. Stethobaroides scutellatus, distal sternites, male (left) and female (right).

FIGURE 4. Stethobaroides, male genitalia, dorsal and lateral aspects. A, S. elcoranus; B, S. villus; C, S. badicrus; D, S. nudiventris (from Toxpam); E, S. permixtus (from La Selva); F, S. lauro. Scale bar 0.5 mm.

FIGURE 5. Stethobaroides scutellatus, male genitalia, dorsal and lateral aspects. A, Nova Teutônia, Santa Catarina, Brazil; B, Piracicaba, São Paulo, Brazil; C, Belém, Pará, Brazil; D, Cayenne, French Guiana. Scale bar 0.5 mm.

FIGURE 6. Stethobaroides, female distal ventrites. A, S. elcoranus; B, S. badicrus; C, S. nudiventris; D, S. scutellatus; E, S. permixtus; F, S. lauro.

FIGURE 7. Stethobaroides scutellatus, female genitalia (scale bar 0.5 mm).