**1. Introduction**

Gastrotricha are meiofauna representatives (encompassing animals ranging in size from about 0.042 to 0.500 mm) living in freshwater and marine ecosystems around the world [1,2]. The *phylum* is divided into two orders—Chaetonotida Remane, 1925 [3] and Macrodasyida Remane, 1925 [3]. The latter group is composed in its majority of hermaphroditic and marine species, which live interstitially in sandy bottoms [2,4]. The order Macrodasyida includes 10 families, 36 genera and approximately 380 described species [2,5,6]. They have a strap-shaped body, a pharynx with pharyngeal pores, and, usually, numerous adhesive tubes in the anterior, lateral and posterior regions.

The family Turbanellidae Remane, 1927 [7] includes six genera: the monospecific *Prostobuccantia* Evans & Hummon, 1991 [8] and Pseudoturbanella d'Hondt, 1968 [9]; *Dinodasys* Remane, 1927 [7] (two species); *Desmodasys* Clausen, 1965 [10] (three species); *Paraturbanella* Remane, 1927 [7] (23 species); and *Turbanella* Schultze, 1853 [11] (32 species).

Although knowledge of phylogenetic relationships within Turbanellidae is still limited, *Turbanella* and *Paraturbanella* species have several common characteristics, but the presence of extraordinary adhesive tubes easily distinguishes the genus *Paraturbanella* from *Turbanella* [2,6,12–16].

The type species of the genus *Paraturbanella* was collected in the Gulf of Naples (Italy) and described as *Paraturbanella dohrni*, based on the presence of an extraordinary pair of accessory adhesive tubes (known also as "*dohrni*", or "*Seitenfüsschen*" in German). Remane could distinguish these animals from the *Turbanella* species [7].

Nowadays, twenty-three species are currently known: *P. africana* Todaro, Dal Zotto, Bownes & Perissinotto, 2017 [17]; *P. aggregotubulata* Evans, 1992 [18]; *P. armoricana* (Swedmark, 1954) [19]; *P. boadeni* Rao & Ganapati, 1968 [20]; *P. brevicaudata* Rao, 1991 [21]; *P. cuanensis* Maguire, 1976 [22]; *P. dohrni* Remane, 1927 [7]; *P. dolichodema* Hummon, 2010 [23]; *P. eireanna* Maguire, 1976 [22]; *P. intermedia* Wieser, 1957 [24]; *P. levantia* Hummon, 2011 [25]; *P. manxensis* Hummon, 2008 [26]; *P. mesoptera* Rao, 1970 [27]; *P. pacifica* Schmidt, 1974 [28]; *P. pallida* Luporini, Magagnini & Tongiorgi, 1971 [29]; *P. palpibara* Rao & Ganapati, 1968 [20]; *P. pediballetor* Hummon, 2008 [26]; *P. sanjuanensis* Hummon, 2010 [23]; *P. scanica* Clausen, 1996 [30]; *P. solitaria* Todaro, 1995 [31]; *P. stradbroki* Hochberg, 2002 [32]; *P. teissieri* Swedmark, 1954 [19]; and *P. xaymacana* Dal Zotto, Leasi & Todaro, 2018 [33].

Herein, we describe a new species of *Paraturbanella* from Brazil, previously reported as *Paraturbanella* sp. 2 [34,35].

## **2. Material and Methods**

#### *2.1. Sampling and Sample Processing*

Information about the description of the new species is mainly taken from specimens found in samples collected by hand from the shallow intertidal area of Praia do Cachadaço, Trindade–Paraty (23◦21 15.8" S, 44◦43 41.5" W), Rio de Janeiro State, Brazil, in October 2017. The sandy sediment was filtered (0.40 μm mesh), and extraction of animals from the sediment was carried out by anaesthetization with MgCl2. The supernatant was poured into a Petri dish, and with a micro-pipette it was possible to separate the gastrotrichs into embryo dishes. Specimens were observed alive with a stereomicroscope ZEISS Stemi 2000. Additional information comes from specimens collected and documented by one of us (M. Antonio Todaro) in 2002 and 2003 [34,35]; the sampling sites and distribution of *Paraturbanella* species along the Brazilian coast were plotted on the map, elaborated using ArcGis [36] (Figure 1), and made available at https://www.arcgis.com/home/webmap/viewer.html?webmap= fafb1d0942b4483a99ddf828fc24039a.

#### *2.2. Microscopical Study—Di*ff*erential Interference Contrast (DIC)*

The gastrotrichs of interest were picked out with a micropipette, mounted on glass slides, and studied using Zeiss Axio Imager M2 plus Differential Interference Contrast optics, with Zen Lite Zeiss software (Zen Blue) and an Axiocam 105 color camera. The observation was taken using a slow-moving living specimen and the measures followed convention [37], according to the position of morphological characteristics along the body. The software used to measure the structures of specimens was Image J.

#### *2.3. Scanning Electron Microscopy (SEM)*

The specimens were fixed in glutaraldehyde 2.5%, rinsed with cacodylate buffer 0.1 M, dehydrated in a graded ethanol series, and critically point dried with CO2. Stubs were coated with gold and analyzed using a scanning electron microscope JSM 5800 LV, with 10 kV voltage.

#### *2.4. Granulometric Analysis*

The particle size analyses were made following the sediment screening method using different opening meshes [38]. A fraction of the sample was separated and oven dried at 60 ◦C for 24 h. The dried material was sieved in different Granutest sieves with progressively smaller openings, and the fraction retained in each sieve was weighed and noted. Through these values, sediment fractions were weighed and granulometric characters (median, standard deviation, skewness and kurtosis) were calculated using GRANPLOTS with line segments [39].

**Figure 1.** Map of Brazil showing the distribution of *Paraturbanella* species. Red: *Paraturbanella tricaudata* species nova (sp. nov.). Green: *Paraturbanella* sp. 1 [34,35]. Orange: *Paraturbanella* sp. 3 [34].
