Thyreomelikertes kongi, Engel & Xie, 2024

Thyreomelikertes kongi , new species

Figures 26–31 View FIGURE 26 View FIGURE 27 View FIGURE 28 View FIGURE 29 View FIGURE 30 View FIGURE 31

DIAGNOSIS: This species, which is known from three individuals (figs. 26, 27, 31A), can be distinguished by the distinctly more elongate fringe, fundal, and corbicular setae on the metatibia (figs. 27, 29, 30, 31A, B), the setae much longer than the maximum metatibal width. Likewise, the setae of the mesotibia are much longer than the maximum mesotibial width (up to about 1.5× mesotibial width) and none of the setae are capitate. The species is overall smaller than that of the type species (refer to metrics) and the apical margin of the metabasitarsus is concave (fig. 30A) (rather than straight). The facial setae, particularly on the clypeus, are seemingly denser than in T. electrosinicus (fig. 31B).

DESCRIPTION: As described for Thyreomelikertes electrosinicus (above), with the following exceptions: WORKER. Total body length (as preserved) 3.51 mm; forewing length (as preserved) 3.78 mm. Head slightly wider than long (fig. 31B), length (summit of vertex to clypeal apical margin) 1.16 mm (paratype 1.21 mm), width (maximum width across compound eyes) 1.66 mm (paratypes 1.32–1.46 mm). Scape elongate, length 0.47 mm (artificially stretched) (paratypes 0.23–0.38 mm, both damaged), longer than torulocellar distance; flagellomere I longer than flagellomere II, shorter than combined lengths of flagellomeres II and III, flagellomere II shorter than flagellomere III. Mesoscutum medial length 0.57 mm; intertegular distance 0.67 mm (paratype 0.55 mm); mesoscutellum medial length 0.36 mm. Metatibia slender, length 1.50 mm (paratypes 1.11–1.61 mm), maximum width 0.45 mm (paratypes 0.22–0.37 mm); metabasitarsus longer than wide, length 0.50 mm (paratype 0.34 mm), maximum width 0.37 mm (paratype 0.22 mm), apical margin concave. Forewing (fig. 28) with basal vein (1M) slightly proximad 1cu-a, pterostigma maximum width at midlength; marginal cell apex well separated from anterior wing margin, with nebulous appendiculate vein; 3Rs much shorter than both r-rs and 4Rs; 1rs-m arched; 2m-cu proximal 2rs-m by about 2–3× vein width.

Mesotibia with dense, erect setae and bristles (fig. 29A), on dorsal surface, such setae and bristles progressively longer from base to apex, setae with some minute branches, retrolateral surface with bristles sparse and setae longer, longer than mesotibial width, such setae with abundant minute branches, no capitate setae; metatibia with dense elongate (distinctly longer than metatibial width), minutely branched setae forming retromarginal fringe (figs. 29B, 30, 31A), similar but shorter setae along proventral margin, retromarginal fringe sparsely intermixed with long, erect bristles and such bristles sparse along anterior edge of proventral surface and inferiorly on prolateral surface, proventral surface largely asetose, prolateral surface with sparsely scattered long, erect, simple setae and bristles, such setae similar on profundal and corbicular surfaces.

QUEEN AND MALE. Unknown.

HOLOTYPE: Female worker, CNU-HYM- LF-2023-003 (figs. 26, 27), in a single piece of amber with two further bees as syninclusions, Fushun coalfield, Liaoning Province, northeastern China, Guchengzi Formation , Ypresian (Eocene); deposited in the fossil insect collection of the Key Laboratory of Insect Evolution and Environmental Changes , College of Life Sciences, Capital Normal University, Beijing, China.

The holotype is preserved in a relatively clear piece of amber and has two syninclusions of the same species as well as a tiny chalcidoid wasp near the wing apex. The holotype is located at one end of the piece, while the two other bees are clustered together and overlapping each other. The holotype is well preserved and can be observed in all orientations except ventral. The wings are obliquely folded over the body and the legs tucked up alongside the body.

PARATYPES: Female workers, CNU-HYM- LF-2023-004 and CNU-HYM-LF-2023-005, in the same piece of amber with the holotype (fig. 26), Fushun coalfield, Liaoning Province, northeastern China, Guchengzi Formation, Ypresian (Eocene) ; deposited in the fossil insect collection of the Key Laboratory of Insect Evolution and Environmental Changes, College of Life Sciences, Capital Normal University, Beijing, China .

The paratypes are distinctly less well preserved relative to the holotype and, given that they are partially entwined as well as damaged through compression or missing sclerites, it was not possible to see each structure as well as in the holotype. It was also not possible to get all of the same measurements from the paratypes as was possible from the holotype. From observable characters, the paratypes agree perfectly with the holotype and so we are confident in their conspecificity with the holotype.

ETYMOLOGY: The specific epithet honors Chuijin Kong, who graciously donated the specimens for this study.