Morphological characters of immature stages of Palaearctic species of Cleopomiarus and Miarus and their systematic value in Mecinini (Coleoptera, Curculionidae, Curculioninae)

Abstract

The relationship between the genera Cleopomiarus and Miarus of Mecinini (Curculionidae, Curculioninae) was tested on the basis of morphological characters from the immature stages. The mature larvae of five Cleopomiarus species (C.distinctus (Boheman, 1845), C.graminis (Gyllenhal, 1813), C.longirostris (Gyllenhal, 1838), C.medius (Desbrochers des Loges, 1893), and C.meridionalis (H. Brisout de Barneville, 1863)), three Miarus species (M.abnormis Solari, 1947, M.ajugae (Herbst, 1795), and M.campanulae (Linnaeus, 1767)), and the pupae of four Cleopomiarus species (C.distinctus, C.graminis, C.longirostris, and C.medius) and two Miarus species (M.abnormis and M.ajugae) are described in detail for the first time. To confirm the taxonomic identification of some larvae, DNA COI barcode was obtained and compared with those of adults. The immature stages of the species herein studied were compared with those known from other genera in tribe Mecinini. It is suggested that Miarus and Cleopomiarus may be monophyletic based on several shared distinctive characters. Larvae of Miarus have a characteristic maxillary mala with six finger-like dms of two sizes (one or two dms very long and the rest of medium length), this feature being apparently unique among weevils. Other genus-specific character states are observed in the pupae, such as the length of setae on the head, rostrum and pronotum, including the number of rs on the rostrum, ds on pronotum, and finally the shape of the urogomphi. A key to the described larvae and pupae were respectively presented. New biological and distributional data on some species are reported.

Immature stages of Palearctic Mecinus species (Coleoptera, Curculionidae, Curculioninae): morphological characters diagnostic at genus and species levels

“…The present detailed descriptions of the immature stages of 12 species of Mecinus constitute a good sample, comprising approximately 20% of the known species of this genus, allowing a comparison with other genera within the tribe Mecinini. Unfortunately, some descriptions previously published on immature stages of species belonging to other genera of Mecinini are somewhat problematic because of missing details about the chaetotaxy and/or the absence of quality drawings (see Skuhrovec et al 2018), making such comparisons still difficult. Only the recent descriptions of six Cleopomiarus and three Miarus species (Skuhrovec et al 2018;Szwaj et al 2018), three Gymnetron species (Jiang and Zhang 2015), and two Rhinusa species (Gosik 2010; Ścibior and Łętowski 2018) were sufficiently complete for such a comparison.…”

“…Unfortunately, some descriptions previously published on immature stages of species belonging to other genera of Mecinini are somewhat problematic because of missing details about the chaetotaxy and/or the absence of quality drawings (see Skuhrovec et al 2018), making such comparisons still difficult. Only the recent descriptions of six Cleopomiarus and three Miarus species (Skuhrovec et al 2018;Szwaj et al 2018), three Gymnetron species (Jiang and Zhang 2015), and two Rhinusa species (Gosik 2010; Ścibior and Łętowski 2018) were sufficiently complete for such a comparison. Skuhrovec et al (2018) emphasised that the taxonomical interpretation of some characters (e.g., thoracic and abdominal dorsal setae) in the papers above is very disputable.…”

“…Only the recent descriptions of six Cleopomiarus and three Miarus species (Skuhrovec et al 2018;Szwaj et al 2018), three Gymnetron species (Jiang and Zhang 2015), and two Rhinusa species (Gosik 2010; Ścibior and Łętowski 2018) were sufficiently complete for such a comparison. Skuhrovec et al (2018) emphasised that the taxonomical interpretation of some characters (e.g., thoracic and abdominal dorsal setae) in the papers above is very disputable. This can cause an incorrect differential diagnosis and preclude the composition of a key to the tribe.…”

“…Our new data might be able to resolve some of these uncertainties. The number of palpomeres of the labial palpi was shown to be one of the most important morphological characters of larvae in this tribe (Skuhrovec et al 2018). Some Gymnetron species have only one palpomere (May 1993;Jiang and Zhang 2015), but the basal state in weevils is the presence of two palpomeres on labial palpi (Marvaldi 1997).…”

“…To date, larvae of only approximately 30 Mecinini species have been described, while descriptions of pupae have been made for 15 Mecinini species (see Skuhrovec et al 2018 for complete references). However, there are only a few detailed descriptions of larvae and pupae that can be used for an adequate taxonomic comparison; these include immatures of three species of Gymnetron (Jiang and Zhang 2015), two species of Rhinusa (Gosik 2010;Ścibior and Łętowski 2018), five species of Cleopomiarus (Skuhrovec et al 2018;Szwaj et al 2018) and three species of Miarus (Skuhrovec et al 2018). In fact, the comparison of approximately ten previously described immatures of mecinines, including two Mecinus species, M. heydenii Wencker, 1866 (Emden 1938) and M. janthinus Germar, 1821 (Scherf 1964), is somewhat problematic due to the absence of important details of the chaetotaxy and/or the absence of quality drawings.…”