Macrocheilus alluaudi Burgeon, 1937

Figs. 1f, 1g, 2e, 3d

Studied material. 1 male: “ Republic of Congo \ Réserve Naturelle des Gorilles de\ Lésio Louna 17– 28.11.2017 \ Batéké Plateau H. Krahnstôver leg.” (Collection P. Sch ̧le, Herrenberg)\\ “ Macrocheilus \ alluaudi \ Burgeon, 1937 ” [h]\ “ A.Serrano det. 2021” [t] [h] .

Remarks. The species was described as a variety of M. labrosus (Dejean, 1831) and later it was elevated to the subspecies level by Basilewsky (1960) due to its well differentiated external morphological characters, such as the absence of a big yellow spot in each elytron (Figs. 1f, 1g) and less dense punctuation on the head and pronotum. Later, it was considered a distinct species without any explanation for the change in taxonomic category (Lorenz 2005; Häckel & Farkač 2013). Taking into account the abovementioned external morphological differences, in addition to the slight different shapes of the labrum and of the median lobe of both forms (cf. Figs. 2e, 3d vs 6e, 7c), we follow the taxonomic treatment given by Lorenz (2005) and Häckel & Farkač (2013). Moreover, the pronotum hind angles in M. alluaudi are rounded while in M. labrosus are dentiform (cf. Figs. 1f, 1g vs Fig. 5i). In addition, the elytral intervals of the former species have a thin polygonal microreticulation not visible in the latter species. The species is known from Democratic Republic of the Congo (Basilewsky 1960) and Republic of the Congo (Lorenz 2021).

Male genitalia (Fig. 3d). Median lobe very slightly different from that of M. labrosus, having a lesser rounded apex and the stripes are membranous in its inner sides; the left paramere is very similar in both species (cf. Figs. 3d and 7c).

Distribution. Congo (Brazzaville), Democratic Republic of the Congo.