Austrolimnius cleidecostae, a new species of riffle beetle (Coleoptera: Elmidae) from Brazil with habitat notes and updated key of the Brazilian species of the genus

ARTICLE Austrolimnius cleidecostae, a new species of riffle beetle (Coleoptera: Elmidae) from Brazil with habitat notes and updated key of the Brazilian species of the genus Thiago Tadeu Silva Polizei¹⁴; Lucas de Souza Machado Costa²³⁵ & Pitágoras da Conceição Bispo²⁶ ¹ Universidade de São Paulo (USP), Museu de Zoologia (MZUSP). São Paulo, SP, Brasil. ² Universidade Estadual Paulista (UNESP), Faculdade de Ciências e Letras, Departamento de Ciências Biológicas, Laboratório de Biologia Aquática. Assis, SP, Brasil. ³ Universidade de São Paulo (USP), Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), Departamento de Biologia, Programa de Pós-Graduação em Entomologia. Ribeirão Preto, SP, Brasil. ⁴ ORCID: http://orcid.org/0000-0003-3746-8865. E‑mail: ⁵ ORCID: http://orcid.org/0000-0002-7104-4508. E‑mail: ⁶ ORCID: http://orcid.org/0000-0002-7356-8882. E‑mail: Abstract. Austrolimnius cleidecostae sp. nov. is one of the smallest species of Elmidae from the Neotropical region. The new species is described and illustrated based on male and female specimens. This species represents the first record in Elmidae of mandibles with an articulated, sclerotized process on inner subapical edge. The specimens were collected from streams in the Atlantic rainforest of São Paulo and Santa Catarina, and habitat notes are given. An updated key for the Austrolimnius Carter & Zeck, 1929 of Brazil is provided. Austrolimnis browni Hinton, 1971 and A. musgravei Hinton, 1939 are recorded for the first time from Brazil. Key-Words. Aquatic beetles; Streams; Neotropical; South America; Taxonomy. INTRODUCTION The cosmopolitan family Elmidae (riffle beetle) is one of the world’s most diverse families of aquatic beetles, with approximately 1,500 species in 153 genera. Austrolimnius Carter & Zeck, 1929 is the second richest genus of the family, with 104 species and two subspecies, occurring in the Australasian and Neotropical regions (Jäch et al., 2016a). About ⅔’s of all described species of this genus occur in Australia and Papua New Guinea. Twenty-one species are in the Neotropical region, seven of which are recorded from Brazil (Jäch et al., 2016a). Austrolimnius species are easily differentiated from those of any other elmid genus by the presence of one or two rows of granules on each epipleuron (Hinton, 1965). Another diagnostic character is the small size, with specimens rarely larger than 2 mm length. In this paper, the male and female of a new species of Austrolimnius from Brazilian rainforest (São Paulo and Santa Catarina states) are described and illustrated. In addition, we present habitat notes, distributional data, new records and an updated key for the Austrolimnius species from Brazil. MATERIAL AND METHODS The specimens were collected in a joint expedition to preserved streams from Atlantic rainforest in São Paulo state (July 2012, 2013) and Santa Catarina state (September and October 2016). The material studied was preserved in alcohol 80% and 96%. Specimens deposited in museums were also studied. The species of Austrolimnius were identified using the taxonomic key of Miranda et al. (2012), the original descriptions, and comparison to photographs of holotypes deposited in the Natural History Museum (BMNH, London, United Kingdom) and the Muséum national d’Histoire naturelle (MNHN, Paris, France). The general morphological terminology follows Kodada et al. (2016). For dissection, mouthparts, abdominal sternites and male genitalia were detached from the specimens and cleared in heated 10% KOH for five minutes (Brown, 1972). Pap. Avulsos Zool., 2020; v.60.special-issue: e202060(s.i.).12 http://doi.org/10.11606/1807-0205/2020.60.special-issue.12 http://www.revistas.usp.br/paz http://www.scielo.br/paz Edited by: Sônia A. Casari / Gabriel Biffi Received: 23/10/2019 Accepted: 05/12/2019 Published: 04/03/2020 ISSN On-Line: 1807-0205 ISSN Printed: 0031-1049 ISNI: 0000-0004-0384-1825 http://zoobank.org/66BC0713-E6E6-49A5-9411-691F8347A169 Pap. Avulsos Zool., 2020; v.60.special-issue: e202060(s.i.).12 2/10 These structures were observed, drawn and then stored on slides using glycerine jelly. The morphological study was done using a Leica WILD M10 stereoscopic microscope. Photographs of the mandibles were taken using a Zeiss Axioskop microscope attached to a camera. Photographs of the adults were taken using a Canon EOS Rebel T3i DSLR camera + Canon MP‑E 65 mm f/2.8 1‑5× macro lens, controlled by Zerene Stacker software. Measurements in millimetres were taken using an Hensoldt/Wetzlar – Mess 10 ocular micrometrics in a Leica M10 stereomicroscope. Photographs were taken from dry specimens. Trace illustrations were made using a ZEISS Axioskop microscope equipped with a camera lucida. Photographs and drawings were edited using Adobe Photoshop CC® and Adobe Illustrator CC®. Type specimen’s labels are quoted verbatim. A change of lines is indicated by “/” and different labels are indicated by “//”. The specimens from São Paulo were collected in alcohol 80% then pinned. The specimens from Santa Catarina were collected and preserved in 96% alcohol and retained in a DNA-grade collection at MZSP. The holotype and paratypes of A. cleidecostae sp. nov. are deposited in the following collections (curator in parentheses). MZSP: USNM: BMNH: Museu de Zoologia da Universidade de São Paulo – São Paulo, Brazil (Sônia Casari). Natural History Museum of Smithsonian Institution, Washington, DC, USA (Terry Erwin). Natural History Museum, London, United Kingdom (Maxwell Barclay). RESULTS Austrolimnius cleidecostae sp. nov. (Figs. 1‑24) Type Material: Holotype male (MZSP): “♂ // Holo- / type // BRASIL. São Paulo. São Miguel / Arcanjo. Parque Estadual Carlos / Botelho. 795 m asl. 16.VII.2013 / 24°08′30,0″S 47°59′41,8″W / Polizei, T.T.S. & Costa, L.S.M. leg. // MZSP 31185 // (MZSP)”. Paratypes (20 specimens): same locality data as holotype (1♂, 1♀, MZSP 31186‑31187; 1♂, 1♀, USNM; 1♂, 1♀, BMNH). “BRASIL. São Paulo. Cunha / Parque Estadual Serra do Mar / 988 m asl. 23°16′28,4″S 45°02′01,6″W / 25.VII.2012 Polizei & Costa leg.” (1♂, 2♀, MZSP 31188‑31190; 1♀, BMNH). “BRASIL. Santa Catarina. Rancho / Queimado. Riacho das Antas. / 791 m asl. 27°41′35,0″S 49°00′38,0″W / 01.X.2016. Polizei, T.T.S. leg.” (4♂, 3♀, MZSP 31194‑31196, 31252‑31255), [in alcohol 96%]. “BRASIL. Santa Catarina. São / Bonifácio. Riacho Dona Bebê. / 470 m asl. 27°54′32,0″S 48°54′47,8″W / 29.IX.2016. Polizei, T.T.S. leg.” (2♂, 1♀, MZSP 31191‑31193) [in alcohol 96%]. Diagnosis: Body subparallel; cuticle alutaceous; general colour dark-brown, with light-yellow antennae, mouthparts, legs and abdominal ventrite V. Mandibles with an articulated sclerotized process on inner subapical edge. Polizei, T.T.S., et al.: Austrolimnius cleidecostae a new species of Elmidae Pronotum with surface alutaceous and without setae, inconspicuously micropunctated, and with longitudinal median impression on basal ⅔ of disc. Epipleura covered by tomen (...truncated)