Contents lists available at ScienceDirect Forest Ecology and Management journal homepage: www.elsevier.com/locate/foreco Meiofaunal diversity in the Atlantic Forest soil: A quest for nematodes in a native reserve using eukaryotic metabarcoding analysis Carla Aristonara Müller a , Leandro de Mattos Pereira a,d , Carina Lopes b , Juvenil Cares b , Luiz Gustavo dos Anjos Borges c , Adriana Giongo c , Carlos Graeff-Teixeira a , Alessandra Loureiro Morassutti a,c, ⁎ a Laboratório de Biologia Parasitária, Escola de Ciências, Laboratório de Parasitologia Molecular, Instituto de Pesquisas Biomédicas, Pontifícia Universidade do Rio Grande do Sul (PUCRS), Av. Ipiranga 6681, 90690-900 Porto Alegre, RS, Brazil b Departamento de Fitopatologia, Instituto de Ciências Biológicas, Universidade de Brasília. Campus Universitário Darcy Ribeiro, Asa Norte, 70910-900 Brasília, DF, Brazil c Laboratório de Geobiologia, Instituto do Petróleo e Recursos Naturais, Pontifícia Universidade do Rio Grande do Sul (PUCRS), Av. Ipiranga 6681, 90690-900 Porto Alegre, RS, Brazil d Faculdade de Teologia e Ciências (FATEC), Rua José Sanches Peres 3040, 5501-210 Votuporanga, SP, Brazil ARTICLE INFO Keywords: Nematode Morphology identification Functional feeding groups SAR Opisthokonta ABSTRACT The assessment of environmental communities may lead to the identification of the novel or not-yet-classified organisms. Few studies have focused on the meiofauna of poorly known habitats such as native soils in sub- tropical forests. We surveyed eukaryotic communities inhabiting soil in an unexplored area of a native Atlantic Forest in southern Brazil using high-throughput sequencing. We analyzed a total of 281,400 sequences using V4 and V9 hypervariable regions of 18S rRNA gene. Opisthokonta was the most abundant supergroup, with Fungi and Metazoa representing an average of 40.6% and 15.8% of the sequences, respectively. Among the metazoan, Nematoda was the second most abundant phylum (4.8%). Isolation and morphological assessment 1745 spe- cimens of nematodes, classified by functional feeding groups as plant parasites (35%), bacterial feeders (30%), omnivores (7%) and predators (5%). Specimens belonged to the class Chromadorea (89.6%) and Enoplea (10.4%).Approximately 65% of them could be morphologically classified only to order level. Results identified a considerable number of newly or still uncharacterized nematodes in soil biota in Atlantic Forest soils. Furthermore, this is the first study in this subtropical area to show that both high throughput sequencing and morphology can give complementary indications of the diversity of nematodes in soil samples. 1. Introduction The Atlantic Forest is a complex biome in South America, known as one of the world’s biological hotspots (Myers et al., 2000). It covers approximately 17% of the Brazilian territory, from northeastern to southeastern (Joly et al., 2014). Studies of eukaryotic microorganisms in Atlantic Forest of southeast Brazil have focused on ciliates (Simão et al., 2017), algae (Sophia et al., 2016); mites and Collembola (Rieff et al., 2016) and parasitic nematodes of animals (Püttker et al., 2008; Ruiz-Torres et al., 2017) and plants (Antes et al., 2012). However, studies of free-living nematodes in this environment are scarce, except for a study that explored nematode trophic structure in phytotelmata of two bromeliad species in the Atlantic Forest of Rio de Janeiro state (Robaina et al., 2015). The total number of worldwide species described of soil nematodes is around 25,000 (Powers, 2004). Nematodes role in on the soil food web, covering several trophic levels, including bacterial and fungal feeders, parasites, predators and omnivores specie (Yeates et al., 1993). The occurrence of free-living nematodes is dependent on changes in each ecological niche, trophic groups, and particular soil character- istics. Nematodes considered as biomarkers of soil quality (Yang et al., 2017, Moura and Franzener, 2017) and have the potential to provide insights related to the structure and functioning of the biogeochemical process in soil, which directly affects the rate of decomposition and nutrients availability (Ritz and Trudgill, 1999). Traditionally, nema- todes species identification have been based on microscopy and mor- phology (Porazinska et al., 2014). However, the analysis of amplified and sequenced small subunit (SSU) rRNA genes has become a standard reference sequence for identification and classification of organisms. Metabarcoding provides short sequences that have been applied to the https://doi.org/10.1016/j.foreco.2019.117591 Received 28 June 2019; Received in revised form 30 August 2019; Accepted 2 September 2019 ⁎ Corresponding author at: Pontifícia Universidade do Rio Grande do Sul, Avenida Ipiranga 6681, prédio 12 CEP, 90690-900 Porto Alegre, RS, Brazil. E-mail address: alessandra.morassutti@pq.cnpq.br (A. Loureiro Morassutti). Forest Ecology and Management 453 (2019) 117591 0378-1127/ © 2019 Elsevier B.V. All rights reserved. T