Pseudostomella dolichopoda Todaro , 2012 and P . cataphracta Ruppert , 1970 ( Gastrotricha : Thaumastodermatidae ) : new records from Brazil and USA and an updated key to the genus

Pseudostomella dolichopoda was originally described from the north coast of São Paulo, Brazil, and P. cataphracta from North Carolina, USA. Herein we report new distributional records of both species: P. dolichopoda is recorded from Espírito Santo, Brazil and P. cataphracta from Florida, USA. An updated identification key for the genus Pseudostomella is also provided.

The genus Pseudostomella was erected by Swedmark (1956) to include species of Gastrotricha with a large preoral apparatus that resembles a mouth, hence the Latin etymology of the genus translates to "false mouth."Pseudostomella belongs to the Thaumastodermatidae, the most speciose family within the order Macro dasyida (Todaro et al. 2011).Presently, Pseudostomella is composed of 17 formally described species of marine macrodasyidans with a world-wide distribution (Todaro et al. 2015) (Figure 1).
The first described species was P. roscovita Swedmark 1956 from Roscoff, France (Swedmark 1956).While numerous species have been described and recorded from across the globe, published distributional records of the genus in both North and South America are generally lacking.In North America, three species of Pseudostomella were found by Ruppert (1970) in North Carolina: Pseudostomella plumosa Ruppert 1970, P. cataphracta Ruppert 1970, and P. roscovita.Subsequently, P. roscovita and P. plumosa have been found along the coastlines of several states and are probably widespread along the Atlantic coast of the USA (Todaro et al. 1995;Hummon 2010).However, P. cataphracta had yet to be recorded from outside its type locality.In South America, reports of the genus were entirely absent until Todaro and Rocha (2004) conducted a survey of marine gastrotrichs along the north coast of São Paulo state and the south coast of Rio de Janeiro state.Todaro and Rocha (2005) found a species of Pseudostomella that remained undescribed until 2012 when it was named P. dolichopoda Todaro, 2012. In 2014, Araújo et al. (2014) described a second species from Brazil, P. squamalongispinosa Araújo, Balsamo & Garraffoni 2014, which was collected on the northeast coast (Bahia state) of Brazil.
Studies of marine gastrotrichs have increased in the past decade with greater attention given to new geographic locations (e.g., Hochberg et al. 2013;Todaro et al. 2014;Kieneke et al. 2015;Garraffoni et al. 2016).In some cases, there is evidence for a more extensive distribution of described species than previously noted (Kieneke et al. 2013), while in others, the range might be questionable due to misidentification or the existence of cryptic species complexes (Todaro et al. 1996;Leasi and Todaro 2009;Kieneke et al. 2012).In this study, we expand the ranges of two species of Pseudostomella in the USA and Brazil based on metric and meristic data, and provide an updated key to the genus to assist in future identifications from new locations.
Sandy sediments containing P. dolichopoda were collected using a corer from the sublittoral (1 m depth) on 6 October 2014 at Praia Grande beach (20°02ʹ25.5ʺS, from Brazil and USA were performed following the protocol reported by Hochberg and Atherton (2010).In both cases samples were placed into buckets and in the laboratory live specimens were sorted using a Leica EZ4 stereomicroscope, mounted on glass slides in seawater/ MgCl 2 solution, observed alive under a PrimoStar Zeiss light microscope and photographed using a Zeiss A1 compound microscope equipped with DIC and a Sony Handycam digital video camera.
The description of the species and the abbreviations used follow the convention of Hummon et al. (1992) and Hochberg and Atherton (2010), where the positions of morphological characters along the body are given in percentage units (U) of total body length as measured from the anterior to posterior end.040°11ʹ00.6ʺW), municipality of Fundão, southern coast of the state of Espírito Santo, Brazil.A photo of a P. dolichopoda specimen is deposited at the Museu de Zoologia, Universidade Estadual de Campinas, Brazil, under accession number 29.Sandy sediments containing P. cataphracta were collected on 14 July 2015 from an offshore site, approximately 7 km east of the Fort Pierce Inlet, Florida, USA.The Smithsonian Marine Station's R/V Sunburst was used to drag a small anchor dredge (29 × 12-cm opening) at approximately 12 m depth (dredge in: 27°28.79ʹN, 080°13.69ʹW; dredge out: 27°29.08ʹN, 080°13.76ʹW) for 15 min.A video of a P. cataphracta specimen is deposited at the Museu de Zoologia, Universidade Estadual de Campinas, Brazil, under accession number 30.Extraction of sediments Pseudostomella dolichopoda Todaro, 2012 (Figure 2) is 375 μm long, with a pharynx of 75 μm length, and with pharyngeal pores at its base.Pharyngeo-intestinal junction (PhIJ) at U30; body slender, elongate, with furcate caudum.Head with 37.5 μm long preoral palps, curving forward; palps possess few sensory hairs and have five and eight papillae on the dorsal and ventral borders, respectively.Thirteen sensory hairs are spaced along the lateral margin of the body.Cuticular armature is composed of pentancres on the entire dorsal and ventrolateral surfaces, except for a T-shaped bare area behind preoral palps.There are two anterior adhesive tubes (TbA) per side arranged in a row, 7 μm long at U8.One dorso-lateral adhesive tube (TbDL) per side inserts on the posterior trunk region.There are 11 ventrolateral adhesive tubes (TbVL) per side, two at the anterior pharyngeal region, seven spaced at the intestinal region, and a further two originate from a common base at end of trunk, with variable length (12-17 μm).Two long pedicles with four adhesive tubes (TbP) per side, three at the tip of each pedicle and the fourth located medially.A continuous field of transverse rows of cilia covers the entire ventral surface from U11 to U36; the field splits in the anterior intestinal region to form paired lateral columns that extend to the anal-genital area at U86.
The single damaged specimen collected in the state of Espírito Santo is slightly larger, 375 μm, than those reported by Todaro (2012), 358 μm.The specimens of the present study are morphologically identical with the original description of P. dolichopoda (Todaro 2012) recorded from São Paulo state.
Pseudostomella cataphracta Ruppert, 1970 (Figures 3-6) is 325 μm long, with a 100 μm long pharynx and a pharyngeo-intestinal junction (PhIJ) at U50. Body slender, elongate and with a furcate caudum.Head with 55 μm long preoral palps, curving forward; palps possess few sensory hairs and are provided with seven papillae (3+1+3) on the dorsal and ventral borders respectively.Sensory hairs are spaced along the lateral margin of the body.Cuticular armature is composed of pentancres on the entire dorsal and ventrolateral surfaces.A triangular area behind the preoral palps is covered by small pentancres (1 μm) (Figure 4).There are three anterior adhesive tubes (TbA) per side forming an arc (6, 8 and 6 μm long) at U15 (Figure 5), three pairs of lateral adhesive tubes (TbL), 24 μm long, at U21/U54/ U75, and 13-14 ventrolateral adhesive tubes (TbVL) per side, 5-15 μm long.Two pedicles are present with five posterior adhesive tubes (TbP) per side (Figure 6): one medial tube (5 μm), three central tubes at the tip of each foot as two short tubes (6 μm) and one elongate tube (18 μm), and a lateral tube (5μm).A continuous field of transverse rows of cilia covers the entire ventral surface of the body.
The single specimen found in Florida is slightly larger than those reported by Ruppert (1970) (300 μm, maximum length found by Ruppert 1970).Morphologically, the specimens of the present study match the original description of P. cataphracta recorded from North Carolina, USA.However, the Florida specimens have longer TbL and median TbP than those described by Ruppert (1970), 15-20 μm long and 12 μm long, TbL and median TbP respectively.
As pointed out by Todaro et al. (2015), species of Pseudostomella appear to have a relatively restricted geographic range, as the majority of them can be found in only one biogeographic region, and sometimes only in the type locality (Figure 1; Table 1).The unique exception among Pseudostomella is P. roscovita, which appears to be a cosmopolitan species since it has been found in the Nearctic, Palearctic and Oriental biogeographic regions (Hummon 2010).
Pseudostomella dolichopoda is widespread along the north coast of São Paulo, as it was found on 10 of 24 beaches sampled by Todaro andRocha (2004, 2005).The coasts of Rio de Janeiro (Todaro and Rocha 2005) and Bahia (Araújo et al. 2014) have also been sampled, but to date, P. dolichopoda has not been found there.The current record of P. dolichopoda in Espírito Santo state is therefore the first time that the species has been found outside São Paulo.This new record extends the range of this species 800 km northwards.
Regarding the biogeography of the two Brazilian species of Pseudostomella (P.dolichopoda and P. squama longispinosa), it is important to note that the Doce river in southeastern Brazil (Espírito Santo state) could be a potential barrier to their dispersal from the north (Bahia) to the south (São Paulo and Rio de Janeiro).The Doce river has an annual average freshwater discharge of 900 m 3 •s -1 (Oliveira et al. 2012) and a sediment discharge 11.22 × 10 6 tons year -1 (Lima et al. 2005), which is likely to disturb the benthic fauna.Until present, P. dolichopoda is only found south of the river outflow and P. squamalongispinosa only to the north.
So far, Pseudostomella cataphracta had a limited range in the USA as it was only found in North Carolina (Ruppert 1970;Hummon 2010) and Georgia (Hummon 2010).This new record from Florida extends the range of this species 200 km southwards.Beyond the USA, this species has also been found in shallow waters in the Mediterranean Sea (Todaro et al. 2006;Hummon 2010), which makes it another candidate for a putative cosmopolitan species of the genus.
Finally, Todaro (2012) provided a taxonomic key for all known species of Pseudostomella plus an unidentified species.However, subsequent publications have added two new taxa (Araujo et al. 2014;Todaro et al. 2015) for which we provide an updated and revised key.Todaro & Tongiorgi, 1993 14b Two TbA;dorsal

CheckFigure 1 .
Figure 1.World map showing the distribution of Pseudostomella species.Black arrow indicates the new report of P. cataphracta and red arrow indicates the new report of P. dolichopoda.