Abstract
Simple SummaryThe detailed descriptions of immature stages of Lachnaeus crinitus Schoenherr, 1826, Rhinocyllus alpinus Gültekin, Diotti and Caldara, 2019 and R. conicus (Frölich, 1792), belonging to the Lixini (Curculionidae: Lixinae), are very important for an increased understanding of the relationship between the species and of the taxonomic and phylogenetic value of the tribes and genera in the Lixinae. The complex of these new data has allowed us to support that (1) Lachnaeus and Rhinocyllus are two valid genera that are different from Larinus, (2) Rhinocyllini is not a tribe different from Lixini, and (3) the separation of Rhinocyllus into two subgenera is rational. In the tribe Lixini, these new data may have an important role, because Rhinocyllus conicus and several other species of the genera Lixus and Larinus have a practical or at least potential use as biological control agents against invasive and noxious weeds.Mature larvae and pupae of Lachnaeus crinitus Schoenherr, 1826 and Rhinocyllus alpinus Gültekin, Diotti and Caldara, 2019 and pupae of R. conicus (Frölich, 1792), belonging to the Lixini (Curculionidae: Lixinae), are morphologically described for the first time. They possess all the characters considered distinctive in the immature stages of this tribe and are distinguishable from all the related genera by a combination of some characters (e.g., presence of endocarina, shape of premental sclerite; the number of pds on the abdominal segments; size and presence of urogomphi). It is emphasized that the controversial tribe Rhinocyllini is not supported by the characters of the larvae and pupae of Rhinocyllus and that the two subgenera of this genus, Rhinocyllus s. str. and Rhinolarinus, are separable from each other not only by characters of the adult but also distinctive characters of the larvae and pupae. These results confirm that the morphology of the immature stages, which is usually overlooked, can be very important for the purpose of identifying new characters that are useful for clarifying taxonomical and phylogenetic complex situations based only on the study of the imagoes.
Highlights
The cosmopolitan subfamily Lixinae of Curculionidae includes approximately 90 genera and 1500 species [1,2], with the largest number of taxa present in the Palaearctic and Afrotropical regions
2–3 pairs of les (except Lixus strangulatus Faust, 1883; (6) antennae one-segmented, each located at the end of frontal suture; sensorium conical, more or less elongated; (7) clypeus trapeziform, mostly with 2 pairs of moderately long cls; (8) epipharynx usually with 5 pairs of als, 3 pairs of ams, and 2 pairs of mes; (9) labral rods well developed, elongated, slightly converging; (10) maxilla with more than 7 dms; (11) praelabium heartshaped or cup-shaped, with a pair of long plbs; (12) ligular setae well developed, 2–3 pairs; (13) meso- and metanotum each transversely divided into two lobes; (14) each pedal area well isolated, with more than 5 long pds; (15) each of Abd
X reduced to four anal lobes of unequal size, dorsal one by far the largest, ventral one very small”. These different traits of mature larvae of Lixini have been confirmed in several descriptions concerning the genus Larinus [3,22,32,33,34,35,36,37,38] and the genus Lixus [20,21,24,31,33,34,39,40,41] but there were more exceptions [21,22] than those presented in Gosik and Wanat [31]
Summary
The cosmopolitan subfamily Lixinae of Curculionidae includes approximately 90 genera and 1500 species [1,2], with the largest number of taxa present in the Palaearctic and Afrotropical regions. Whereas all the authors are concordant in accepting two tribes, Lixini and Cleonini, a third tribe, Rhinocyllini, is controversial This tribe was proposed by Lacordaire [6] for the genera Rhinocyllus and Microlarinus Hochhuth, 1847 and briefly described with the following sentence: “Rostrum at the most as long as the head, angulate and dorsally flat; scrobes anteriorly complete”. His opinion was followed by Capiomont [7], Petri [8] and Csiki [1], who included the genus Bangasternus Des
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