Baryorygma Engel, 2022

Engel, Michael S., 2022, Notes on South American stingless bees of the genus Scaptotrigona (Hymenoptera: Apidae), Part III: A revised infrageneric classification and new species, Journal of Melittology 2022 (111), pp. 1-29 : 24-25

Baryorygma Engel , new subgenus

ZooBank: urn:lsid:zoobank.org:act:EEF2D9F6-C4E4-4F6C-8DB7-C66F0A9808B1

TYPE SPECIES: Scaptotrigona fimbriata Engel, new species .

DIAGNOSIS: This subgenus superficially resembles Eoscaptotrigona but can be easily distinguished by the presence of vitreous yellow to yellow markings on the lower face ( Figs. 37, 38 , 40 ) (chestnut brown to black in Eoscaptotrigona ), and the more widely spaced punctures of the upper frons, with the punctures separated by 1–2× a puncture width (separated by much less than a puncture width or even contiguous in Eoscaptotrigona ). In addition the subgenus has a largely dark brown to black integument (aside from the aforementioned facial markings); the bristles of the vertex, mesoscutum, and mesoscutellum distinctly longer than the median ocellar diameter; the scape lacks minute, erect to suberect bristles along its length; terga without a dense covering of elongate, erect, simple, yellow setae (present only in Dasytrigona ); terga III–V are not covered in yellow tomentum, but may have whitish tomentum to varying degrees laterally on terga IV–V or on the disc of tergum VI; and the discs of metasomal terga III–V have abundant, erect to subdecumbent bristles. The facial markings are similar to those observed in some species of Gymnotrigona and Scaptotrigona s.str., likely reflecting a relationship closer to these subgenera than the otherwise putatively plesiomorphic Eoscaptotrigona .

ETYMOLOGY: The new subgeneric name is a combination of the Ancient Greek adjective βᾰρῠ́ς (barús, meaning, “heavy”), and the noun ὄρῠγμᾰ (órugma, meaning, “trench”), as an allusion to these including some of the larger and more robust species of Scaptotrigona and the excavated trench of the mesoscutellum (from which the genus takes its name: σΚᾰ́πτω / skáptō, meaning, “to dig out”). The gender of the name is neuter.

Key to Species of Baryorygma

1. Metasomal sternal setae light fuscous to white ...................................................... 2

—. Metasomal sternal setae dark fuscous to black [ Guyana] ... S. emersoni (Schwarz)

2(1). Apical margins of metasomal terga II–V without fimbriae ............................... 3

—. Apical margins of metasomal terga II–V with fimbriae composed of fine, plumose, white to slightly yellowish setae ( Fig. 41 ) [ Bolivia] ...... S. fimbriata , n. sp.

3(2). Metasomal tergum I with bristles laterally; larger species, head widths 2.81– 2.94 mm [South American] ....................................................................................... 4

—. Metasomal tergum I without bristles laterally; smaller species, head widths 2.62–2.75 mm [ Costa Rica, Panama] ........................ S. subobscuripennis (Schwarz)

4(3). Clypeus and supraclypeal area chestnut brown to dark brown, and lower paraocular area with circular area of vitreous yellow to yellow brown bordering clypeus and lower outer margin of antennal torulus but widely separated from inner orbit ( Fig. 37 ); metasomal terga I and II with short bristles laterally [ Bolivia, Brazil, Peru] ........................................ S. bipunctata (Lepeletier)

—. Clypeus and supraclypeal area yellow to yellow brown, sometimes with longitudinal streaks of brown, and lower paraocular area yellow from inner orbit to clypeus, although brown below near clypeal apex and above at upper tangent of antennal toruli ( Fig. 38 ); metasomal terga I and II with long bristles laterally [ Bolivia, Brazil, Peru] ............................................................ S. tricolorata Camargo

Figures

Figures 37–38. Facial views of workers of Scaptotrigona Moure. 37. Scaptotrigona (Baryorygma) bipunctata (Lepeletier). 38. S. (B.) tricolorata Camargo.

Figures 39–41. Worker of Scaptotrigona (Baryorygma) fimbriata, new species. 39. Lateral habitus. 40. Facial view. 41. Dorsal view of metasoma.