It is a mess! How many species are in Rivudiva trichobasis Lugo-Ortiz &amp; McCafferty, 1998 (Ephemeroptera: Baetidae)?

Paulo Vilela Cruz,Neusa Hamada,Cláudia R.T De Lima,Rafael Boldrini

doi:10.5852/ejt.2022.789.1639

Abstract

The original description of Rivudiva trichobasis Lugo-Ortiz & McCafferty, 1998 is short, with few illustrations. The lack of information resulted in a broad specific diagnosis, with emphasis on the spine-like setae on the antenna. Our hypothesis is that the lack of information resulted in many species being hidden behind R. trichobasis name. We evaluated the species R. coveloae (Traver, 1971) and R. venezuelensis (Traver, 1943) considering the new evidence. After analyzing the paratype of R. trichobasis and records of the species in Brazil, the hidden-species hypothesis was corroborated. Five new species were identified among the published records of R. trichobasis of which four are described here: R. amazona sp. nov. (Roraima State), R. oxum sp. nov. (Rondônia State), R. uiara sp. nov. (Amazonas State), R. naia sp. nov. (Roraima State). The fifth species, Rivudiva sp. X from Maranhão State, could not be described due to the poor conservation of the specimen and is therefore left in open nomenclature. Records from Espírito Santo State (Brazil) and from Paraguay are treated as putative and must be evaluated considering the new evidence. Rivudiva venezuelensis and Rivudiva coveloae are diagnosed and illustrated based on type material. After analyzing these two species, we hypothesize that only R. coveloae likely belongs to the genus Rivudiva. However, information on the nymphal stage is needed to corroborate this hypothesis.

Highlights

The genus Rivudiva Lugo-Ortiz & McCafferty, 1998, recently established, already has a rich history
The authors described the male imago of the genus for the first time (R. minantenna) and, mainly based on a pointed projection on the posterior margin of the subgenital plate, transferred two species only known by their adults to the genus Rivudiva: R. coveloae (Traver, 1971) and R. venezuelensis (Traver, 1943)
The specimens analyzed in the present study are deposited in the Instituto de Biodiversidad Neotropical (IBN) – R. trichobasis LugoOrtiz & McCafferty, 1998; Instituto Nacional de Pesquisas da Amazônia (INPA) – R. amazona sp. nov., R. oxum sp. nov. and R. uiara sp. nov.; Universidade Federal de Roraima (UFRR) and Universidade Federal de Viçosa (UFV) – R. naia sp. nov. and R. sp

Summary

Introduction

The genus Rivudiva Lugo-Ortiz & McCafferty, 1998, recently established (compared to other genera in the family), already has a rich history. Two years later, Orth et al (2000) reported the genus from French Guyana without specific identification and Salles et al (2004) reported R. minantenna from Rio de Janeiro State, Brazil, considerably extending its known distributional range. The genus was treated as rare until Salles & Nascimento (2009), during a mayfly survey in the Southeastern Region of Brazil, found a good series of nymphs of R. minantenna and reared a few of them in the field. The authors described the male imago of the genus for the first time (R. minantenna) and, mainly based on a pointed projection on the posterior margin of the subgenital plate, transferred two species only known by their adults to the genus Rivudiva: R. coveloae (Traver, 1971) and R. venezuelensis (Traver, 1943)

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Conclusion