Trigona ( Nostotrigona ) Engel, 2021

Key of the Trigona ( Nostotrigona) Engel, 2021 species from Brazil (workers)

1. Face with wide distance between the epistomal suture and the lower tangent of the antennal socket of approximately 0.7× scape diameter ( Fig. 6A and D View FIGURE 6 ); post-ocellar carina strongly elevated................................................. 2

– Face with narrow distance between the epistomal suture and the lower tangent of the antennal socket of approximately 0.3× scape diameter ( Fig. 6G, J and M View FIGURE 6 ); post-ocellar carina short and smooth......................................... 3

2(1). Scape with erect setae approximately 0.9× scape diameter ( Fig. 6B View FIGURE 6 ); metasoma elongated, approximately 2× longer than wide............................................................................ Trigona recursa Smith, 1863 View in CoL .

– Scape with erect setae approximately 1.3× scape diameter ( Fig. 6E View FIGURE 6 ); metasoma subtriangular, approximately 1.2× longer than wide........................................................................... Trigona daianeae sp. nov.

3(1). Metabasitarsus distinctly enlarged on the apical half of the posterior margin, forming an acute angle ( Fig. 6I View FIGURE 6 ); mesoscutum with long setae ( 0.26 mm), approximately 1.9× the scape diameter; labrum slightly protuberant medially.................................................................................................... Trigona juvenili sp. nov.

– Metabasitarsus with rather parallel sided, their posterior apical extremity almost rectangular to slightly produced downward ( Fig. 6L and O View FIGURE 6 ); mesoscutum with relatively short setae (between 0.19 mm to 0.22 mm), approximately 1.5× the scape diameter; labrum rounded medially............................................................................... 4

4(3). Metasoma subtriangular, approximately 1.2× longer than wide ( Fig. 7A View FIGURE 7 ); upper frons with erect setae approximately 0.8× scape diameter................................................................ Trigona permodica Almeida, 1992 View in CoL .

– Metasoma elongated, approximately 2× longer than wide ( Fig. 7B View FIGURE 7 ); upper frons with erect setae approximately 1.4× scape diameter.................................................................... Trigona mandaloriana sp. nov.