Sistemática de Gyrinus geoffroy, 1762 (Coleoptera: Gyrinidae)

Abstract

Gyrinus Geoffroy, with more than 200 described species, has worldwide distribution and it is classified in four subgenres, three of which occur in the Neotropical region: G. (Gyrinus), G. (Neogyrinus) and G. (Oreogyrinus). Most of the paper on Neotropical Gyrinus species refers to old, poorly detailed descriptions with no illustrations and was published until the mid-20th century. The original descriptions contain variable characters, such as coloring, and most of them do not treat the variations occurring in widely distributed species. The Gyrinus species of the Neotropical region have never been reviewed and this fact has always been addressed by other authors with an indication of the necessity to carry out this review, especially due to the presence of many synonyms and erroneous identifications in the group. Thus, the objectives of this work were: to review the species of subgenus G. (Oreogyrinus) and G. (Neogyrinus), to describe new species, to test the validity of G. (Neogyrinus) and G. (Oreogyrinus) subgenus by means of a cladistic method and to associate adults and immatures using molecular techniques and / or rearing in laboratory conditions and describing associated immatures including larval chaetotaxic analysis and bionomic information about the group. In Chapter I it is presented the revision of G. (Neogyrinus) and G. (Oreogyrinus), with information on distribution and hábitat, and is provided a dichotomous key for males of G. (Neogyrinus) and G. (Oreogyrinus). All species G. (Neogyrinus) and G. (Oreogyrinus) were redescribed, new synonyms were established, the species incertae sedis (G. galapagoensis) was transferred to G. (Oreogyrinus). In Chapter II, the validity of G. (Oreogyrinus) and G. (Neogyrinus) was tested by means of a phylogenetic analysis and the relation of these with the other subgenera was hypothesized. For this purpose, 50 characters related to external and internal morphology were analyzed. Gyrinus (Neogyrinus) was recovered as a monophyletic group unlike G. (Oreogyrinus) which was recovered as an unnatural group, with species allocated in the same clade as G. (Gyrinus), according to the results and discussion is proposed that this subgenus as synonym of G. (Gyrinus). In chapter III, immature and adults of G. (Neogyrinus) rozei Ochs were associated by breeding in laboratory conditions and by means molecular techniques, allowing the morphological description of eggs, the three larval instars and the pupa of this species. Also, a species of Melanosmicra sp. (Hymenoptera: Chalcididae) was recorded as parasitoid of G. (Neogyrinus) rozei pupae. In chapter IV, a new species, Gyrinus (Oreogyrinus) rhyssonotum Colpani, Benetti & Hamada, 2019 has described for the Northern Amazon. Thus, according to the results of this study, the taxonomic changes propose, and the new species described, Gyrinus has now 43 valid neotropical species. The phylogenetic analysis showed that G. (Oreogyrinus) is paraphyletic and is now synonymized with G. (Gyrinus). Also, the immatures G. (Neogyrinus) rozei are described for the first time with the inclusion of bionomic information.