Carinumerus undetermined

Carinumerus spp. (Fig. 14B, E) Five additional specimens of Carinumerus Caterino, 2021 are reported (deposited in TZC). These specimens are closely related to each other and to C. intricatus and C. yingae. However, they display a range of subtle variation in the form of pronotal carination, namely in the sharpness and height of the ridges. We propose these either represent a morphologically variable species or a complex of closely related species. The morphological variation may also be caused by deformations. In one of these specimens some body parts (e.g. head and mouthparts, legs) are exposed and clearly visible, illuminating additional generic characters: Head: Vertex finely punctuate; frons flat roughly punctuate, without frontal stria; supraoccipital area elevated, keel-like. Clypeus almost smooth. Labrum relatively long (length: width ratio 2: 3), with a pair of long prominent setae. Mandibles with several marginal setae. Eye very large, triangular. Prosternum incised for antennal passage, antennal cavity located in anterior prosternal angle. Pygidium with a median longitudinal carina, basally diverging in two curved carinae extending laterally. Profemur with two rows of large punctures ventrally. Protibia with a tarsal groove. Additionally, in specimens 1–4 openings can be seen in posterior pronotal angles (Fig. 14B, E). These could be interpreted as potential mycangia (equivalent in some recent Histeridae; Kovarik and Caterino 2016). In spec. 1 an elongate bubble rises from the depression (Fig. 14E), which can possibly be interpreted as exudate coming from the gland (Zhou et al. 2019) or trapped air.