Stethobaroides scutellatus Casey, 1922

Prena, Jens, 2025, Neotropical orchid-weevils of the genus Stethobaroides Champion (Coleoptera, Curculionidae, Baridinae), Zootaxa 5723 (2), pp. 227-244 : 238-240

Stethobaroides scutellatus Casey

( Figs. 3 , 5 , 6D , 7 , 11A )

Stethobaroides scutellatus Casey, 1922: 413 . Holotype male (USNM, type 45667).

Diorymerellus vigintiestriatus Fonseca, 1957: 243 . Five of 13 syntypes at CEAH, lectotype not designated. New synonymy. Stethobaris vigintiestriata : Wibmer & O’Brien (1986: 329).

Diagnosis. Stethobaroides scutellatus belongs to a complex of short ovate species found in South America and along both sides of the Central American mountain ranges ( Fig. 11 ). Presently it is the only named representative of the genus in South America and can be distinguished from morphologically similar species from Central America and the abutting lowlands west of the Andes by sexual characteristics and allopatry. Diagnostic is the fifth ventrite of the female, with widely spaced punctation and gently bisinuate distal margin ( Fig. 6D ). Stethobaroides lauro and specimens from the Pacific lowlands west of the Andes have a similar penis ( Figs. 4F , 5 ) but their females have the fifth ventrite distally more strongly curved ( Fig. 6F ) than female S. scutellatus ( Fig. 6D ). The Mexican S. elcoranus is larger (3.4–3.8 vs. 2.7–3.3 mm), slightly more elongate and ventrally finely setose ( Fig. 8 ).

Life history. Garlet et al. (2025) found S. scutellatus in the flowers of thirteen species and hybrids of Catasetum Rich. ex Kunth but, apparently, on no other orchid genus. The development in Catasetum is currently under investigation at the Department of Entomology and Acarology, ESALQ, University of São Paulo (P. Sanz Veiga, personal information). Fonseca (1957) reported that eggs were laid in the ovary and stem of Cattleya and Laelia species and that the larvae damaged the flowers. I have seen no S. scutellatus specimens collected from these orchid genera. Other contemporary sources, like Monte (1942) and Ferreira Lima (1943), mentioned exactly the same orchid genera as hosts for orchid weevils with a covered pygidium.

Distribution. The species occurs from French Guiana down to the South Region of Brazil (Região Sul do Brasil) but apparently not on the Pacific side of the Andes.

Material examined. BRAZIL. Pará, Belém ( JPPC 8 ) ; Santa Catarina, Nova Teutônia ( JPPC 6 ) ; São Paulo, Piracicaba ( JPPC 9 ) , São Paulo, digital images of syntypes of D. vigintiestriatus ( CEAH 5 ) ; “ Amazones ”, holotype of S. scutellatus ( USNM 1 ) ; Brazil without locality ( NHRS 5 , SNSD 2 ) . FRENCH GUIANA. Cayenne ( NHRS 1 , SNSD 2 , ZNS 1 ) .

Additional records. BRAZIL. Goiás, Goiânia, greenhouse ( P. Sanz Veiga, personal information) ; Mato Grosso, Alta Floresta ( Garlet et al. 2025); Pará, Ananindeua ( P. Sanz Veiga, personal information) .

Notes. Thomas Casey purchased his specimen, a male with origin “Amazones”, from the French insect trader Jules Desbrochers des Loges ( Casey 1922). Several European collectors owned this species and Johannes Faust, one of the most knowledgeable contemporary weevil experts, had applied to it the manuscript name Centrinus anthracinus . SNSD houses four of Faust’s specimens, three originally coming from the Austrian beetle collector Franz Pipitz and one from the French collector Edmond Fleutiaux. Two of Faust’s specimens are from Cayenne in French Guiana (Fleutiaux 1, Pipitz 1) and two from “Brasilia” (Pipitz 2). Even though it is conceivable that all these historical specimens were distributed by Desbrochers, their heterogeneous label data provide no clue about the exact provenance of Casey’s type specimen.

Priscila Sanz Veiga (UNESP Botucatu, Brazil) examined five syntypes of Diorymerellus vigintiestriatus at CEAH. Based on her observations and images, I consider D. vigintiestriatus as a junior subjective synonym of S. scutellatus ( new synonymy). An unidentified female specimen from the Nicoya Peninsula in Costa Rica, found by Corrales Moreira & Rivera Coto (2003) in an orchid nursery together with a male near S. lauro (see notes there), is exceedingly similar to S. scutellatus . With the available resources, I am unable to ascertain if this pair represents a single species and whether the female is from the region or introduced with traded plants.

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).

FIGURE 8. Stethobaroides elcoranus from Finca El Cora, Nayarit, México. A–C, male, L=3.8 mm; D, female, L=3.4 mm.

FIGURE 11. Stethobaroides, dorsal and lateral aspects of males. A, S. scutellatus from Piracicaba, São Paulo, Brazil; L=2.6 mm. B, S. permixtus from La Selva Reserve, Heredia, Costa Rica; L=2.7 mm; C, S. lauro from Agirre, Puntarenas, Costa Rica; L=2.6 mm.