Hypotrigonina

Engel, Michael S., Herhold, Hollister W., Davis, Steven R., Wang, Bo & Thomas, Jennifer C., 2021, Stingless bees in Miocene amber of southeastern China (Hymenoptera: Apidae), Journal of Melittology 2021 (105), pp. 1-83 : 55-64

publication ID	https://doi.org/ 10.17161/jom.i105.15734
publication LSID	lsid:zoobank.org:pub:3637F70F-42FC-461E-82B3-A847752A071A
persistent identifier	https://treatment.plazi.org/id/51B937DB-6BB2-464F-93D8-C9344D8C8DE9
taxon LSID	lsid:zoobank.org:act:51B937DB-6BB2-464F-93D8-C9344D8C8DE9
treatment provided by	Felipe
scientific name	Hypotrigonina
status

Treatment

Subtribe Hypotrigonina Engel

The classification of African Meliponini employed herein ( Table 2 and section on Hypotrigonitae , vide supra), differs in various ways from those in the literature (e.g., Eardley, 2004; Michener, 2007). Accordingly, a key is provided to the genera and subgenera as they are conceived here, with the proposal of a new subgenus within Axestotrigona . To make the key as easy to use as possible, images are provided to all of the genera as they are circumscribed here given that they are not as often figured in the literature as are Neotropical stingless bees: Liotrigona s.str. ( Figs. 65 View Figures 65–68 , 69 View Figures 69–71 , 72 View Figures 72–75 , 76, 77 View Figures 76–83 , 84 View Figures 84–87 ), Liotrigona (Cleptotrigona) ( Figs. 67 View Figures 65–68 , 70 View Figures 69–71 , 73 View Figures 72–75 , 80, 81 View Figures 76–83 , 85 View Figures 84–87 ), Hypotrigona ( Figs. 66 View Figures 65–68 , 71 View Figures 69–71 , 74 View Figures 72–75 , 78, 79 View Figures 76–83 , 86 View Figures 84–87 ), Dactylurina ( Figs. 68 View Figures 65–68 , 75 View Figures 72–75 , 82, 83 View Figures 76–83 , 87 View Figures 84–87 ), Plebeina ( Figs. 88–93 View Figures 88–93 ), Meliponula ( Figs. 94 View Figures 94–97 , 98 View Figures 98–101 , 102 View Figures 102–105 , 109 View Figures 106–111 , 113 View Figures 112–115 ), Plebeiella ( Figs. 95 View Figures 94–97 , 99 View Figures 98–101 , 103 View Figures 102–105 , 112 View Figures 112–115 ), Meliplebeia s.str. ( Figs. 96 View Figures 94–97 , 100 View Figures 98–101 , 104 View Figures 102–105 , 106, 107, 110 View Figures 106–111 , 114 View Figures 112–115 ), Meliplebeia (Apotrigona) ( Figs. 97 View Figures 94–97 , 101 View Figures 98–101 , 105 View Figures 102–105 , 108, 111 View Figures 106–111 , 115 View Figures 112–115 ), Axestotrigona ( Figs. 116–121 View Figures 116–121 ).

Key to Genera and Subgenera of African Meliponini View in CoL (worker caste; modified from Michener, 2007)

1. Forewing length less than 3.5 mm; hind wing without closed cells, veins closing radial and cubital cells, if visible at all, clear and unpigmented; forewing with 2Rs, 1rs-m, and 2rs-m almost always completely absent, thus indications of submarginal cells absent ( Figs. 69–71 View Figures 69–71 ); at least distal part of second cubital cell (= subdiscoidal cell) of forewing undefined or defined by completely unpigmented vein traces ( Figs. 69–71 View Figures 69–71 ); vein 2M of forewing terminating without bend at about position of anterior end of 1m-cu (i.e., 3M absent), which, however, is absent or spectral ( Figs. 69–71 View Figures 69–71 ) .................................................................... 2

—. Forewing length about 4 mm or more; hind wing commonly with radial and cubital cells closed by at least weakly brownish nebulous veins (e.g., Fig. 112 View Figures 112–115 ); forewing with 2Rs and 1rs-m usually weakly indicated, first submarginal cell thus usually recognizable ( Figs. 92 View Figures 88–93 , 112–115 View Figures 112–115 , 120 View Figures 116–121 ); second cubital cell of forewing completely indicated, at least by faint veins ( Figs. 92 View Figures 88–93 , 112–115 View Figures 112–115 , 120 View Figures 116–121 ); vein M of forewing extending at least slightly beyond position of anterior end of 1m-cu and angulate at end of that crossvein (i.e., 3M distinct from 2M, with at least tubular to nebulous stub), which is usually at least faintly visible ( Figs. 92 View Figures 88–93 , 112–115 View Figures 112–115 , 120 View Figures 116–121 ) ............................................................................................................... 4

2(1). Distal part of prolateral surface of metatibia flat or concave, margined by long setae, forming corbicula ( Figs. 76, 78, 82 View Figures 76–83 , 90 View Figures 88–93 , 106, 108, 109 View Figures 106–111 , 117 View Figures 116–121 ); penicillum present (e.g., Figs. 110, 111 View Figures 106–111 ); clypeus twice as wide as long or less ( Figs. 72, 74 View Figures 72–75 ) ...... 3

—. Prolateral surface of metatibia convex, without corbicula ( Fig. 80 View Figures 76–83 ); penicillum absent ( Fig. 80 View Figures 76–83 ); clypeus much more than twice as wide as long ( Fig. 73 View Figures 72–75 ) ............ .................................................................................. Liotrigona (Cleptotrigona) Moure View in CoL

3(2). Superior distal angle of metatibia forming distinct angle ( Figs. 76, 77 View Figures 76–83 ); mesoscutum and mesoscutellum smooth and shining ( Fig. 84 View Figures 84–87 ); gonostyli much longer than broad, flat, adjacent or separated by less than one gonostylar diameter, without setae but with gonotrichia ................ Liotrigona (Liotrigona) Moure , s.str.

—. Superior distal angle of metatibia a rounded contour ( Figs. 78, 79 View Figures 76–83 ); mesoscutum and mesoscutellum mate, microalveolate to imbricate ( Fig. 86 View Figures 84–87 ); gonostyli minute, tuberculiform, separated by several gonostylar diameters, with setae but without gonotrichia .................................................................... Hypotrigona Moure View in CoL

4(1). Retrolateral surface of metatibia with depressed upper marginal glabrate area narrow (much less than half as wide as broad area with keirotrichia) or absent ( Figs. 91 View Figures 88–93 , 107 View Figures 106–111 , 118 View Figures 116–121 ), keirotrichia extending to or close to margin; first metasomal segment broader than long ( Fig. 68 View Figures 65–68 ) ......................................................................... 5

—. Retrolateral surface of metatibia with strongly depressed, shining, superior marginal glabrate area nearly as broad apically as longitudinal median keirotrichiate plateau ( Fig. 83 View Figures 76–83 ), and about half as wide as keirotrichiate plateau midway of metatibial length; first metasomal segment longer than broad ( Fig. 68 View Figures 65–68 ) .............................................................................................. Dactylurina Cockerell View in CoL

5(4). Metatibia rather spoon-shaped, superior distal angle rounded but with coarse, amber-colored to blackish bristles (superior parapenicillum) ( Figs. 106, 108, 109 View Figures 106–111 , 117 View Figures 116–121 ); sting stylet distinct, acute ......................................................................... 6

—. Metatibia slender, triangular with distinct superior distal angle supporting long, pale setae (not especially coarse) ( Fig. 90 View Figures 88–93 ); sting stylet a mere rounded convexity ................................................................................................... Plebeina Moure View in CoL

6(5). Propodeal profile with slanting dorsal portion rounding onto vertical portion; corbicula occupying more than distal half of metatibia ( Figs. 106, 108 View Figures 106–111 , 117 View Figures 116–121 ); metasomal terga at least partly shining [apical reflexed process of sternum VI of male longer than body of sternum] ..................................................................... 7

—. Propodeal profile largely vertical; corbicula occupying less than distal half of metatibia ( Fig. 109 View Figures 106–111 ); metasomal terga dull, minutely sculptured [apical reflexed process of sternum VI of male short and rounded] ............. Meliponula Cockerell View in CoL

7(6). Head and mesosoma without yellow markings ( Figs. 116, 119 View Figures 116–121 ); retrolateral surface of metatibia without well-defined, shining, depressed superior margin ( Fig. 118 View Figures 116–121 ), although keirotrichiate area does not reach margin at least distally [Genus Axestotrigona Moure View in CoL , s.l.] .............................................................................. 8

—. Head and mesosoma with yellow markings ( Figs. 95, 97 View Figures 94–97 , 99–101 View Figures 98–101 , 103–105 View Figures 102–105 ); retrolateral surface of metatibia with shining superior margin (e.g., Fig. 107 View Figures 106–111 ), at least slightly depressed .............................................................................................. 9

8(7). Basal area of propodeum finely tessellate to microalveoate, sometimes faintly so and appearing nearly smooth, and laterally setose (sometimes lateral patches of setae sparse and wispy or may be difficult to discern in worn individuals or those with considerable pitch on the body) ( Fig. 121 View Figures 116–121 ); wing membranes hyaline clear to lightly infuscate (parchment-colored) or ferruginous ( Figs. 116, 120 View Figures 116–121 ) .... ............................................................................................ Axestotrigona Moure View in CoL , s.str.

—. Basal area of propodeum glabrous and smooth; wing membranes darkly infumate throughout .................................................... Atrichotrigona Engel , n. subgen.

9(7). Basal area of propodeum pubescent [Genus Meliplebeia Moure View in CoL , s.l.] ................ 10

—. Basal area of propodeum glabrous ................................................ Plebeiella Moure View in CoL

10(9). Mesoscutum tessellate ( Fig. 104 View Figures 102–105 ); mandibular teeth small; scape as long as antennal-ocellar distance ( Fig. 100 View Figures 98–101 ); basal vein (1M) slightly distad 1cu-a ( Fig. 114 View Figures 112–115 ); superior parapenicillum well developed ( Figs. 106, 107, 110 View Figures 106–111 ) ........................ ................................................................................................ Meliplebeia Moure View in CoL , s.str.

—. Mesoscutum punctate ( Fig. 105 View Figures 102–105 ); mandibular teeth strong; scape shorter than antennal-ocellar distance ( Fig. 101 View Figures 98–101 ); basal vein (1M) slightly basad 1cu-a ( Fig. 115 View Figures 112–115 ); superior parapenicillum scarcely definable ( Fig. 111 View Figures 106–111 ) ..... Apotrigona Moure