Chelostoma meronense, Müller & Pisanty & Dorchin, 2025

Chelostoma meronense species group

The three representatives of the Chelostoma meronense species group are characterised in both sexes by the very long mouthparts with the second segment of the labial palpus being distinctly longer than the compound eye and the proboscis surpassing the coxa of the fore leg when folded ( Fig. 19 View FIGURES 19–29 , 30–31 View FIGURES 30–39 , 40–41 View FIGURES 40–48 ). They share this character with the four representatives of the C. grande species group. The females can be separated from the latter group by i) the body length, which is less than 8 mm, ii) the labrum, which is at most 2× as long as apically wide ( Fig. 21 View FIGURES 19–29 ), and iii) the terga 2–3, which are basally not or only weakly constricted ( Fig. 30 View FIGURES 30–39 , 40 View FIGURES 40–48 ). The males differ by i) the apical margin of sternum 1, which is medially distinctly emarginate, ii) the median projection of sternum 2, whose apex is directed anteriorly and projecting over the sternal base ( Fig. 27 View FIGURES 19–29 , 38 View FIGURES 30–39 , 46 View FIGURES 40–48 ), and iii) the sternum 3, which bears a row of stiff yellowish bristles along its apical margin ( Fig. 29 View FIGURES 19–29 , 39 View FIGURES 30–39 , 48 View FIGURES 40–48 ). Due to the most probable pollen specialisation of C. meronense on Lamiaceae (see below) and the long proboscis in combination with the narrow and elongated head suggesting long-tubed flowers as hosts, the other two species of this group are likely also Lamiaceae oligoleges.