First records of Pseudozeuxidae and Metapseudinae (Metapseudidae) (Crustacea, Tanaidacea) in Southwestern Atlantic, with descriptions of two new species

Based on specimens collected from eulittoral zone in rocky shores of northeast of Rio de Janeiro (Brazil) on 2017, two new tanaidaceans species from two different suborders are described: Apseudomorpha brasiliensis sp. nov. (Apseudomorpha, Metapseudidae) and Pseudozeuxo fischeri sp. nov. (Tanaidomorpha, Pseudozeuxidae). Diagnostic characters of Apseudomorpha brasiliensis are mandible palp article-2 and article-3 with six and nine finely penicillate setae on inner margin, respectively; pereopod-1 carpus and propodus with two and four ventral spines, respectively; pleonites 2 and 5 with pleura having long distal seta; uropod exopod shorter than endopod articles 1–2 combined, endopod four-articled. Pseudozeuxo fischeri is characterized by pereopods 1–3 coxa with long seta about half as long as basis; pereopods 2–3 carpus with ventrodistal seta; propodus with two ventral setae; pereopods 4–6 propodus with two ventral spines and one seta; uropod endopod twoand exopod one-articled. This is the first record of the family Pseudozeuxidae and the metapseudid subfamily Metapseudinae from the Southwestern Atlantic (Brazil). Remarks on their associations with macroalgae and identification keys to world species of Apseudomorpha and Pseudozeuxo are provided.


Introduction
Current knowledge about the crustacean order Tanaidacea Dana, 1849 is still significantly underdeveloped, with the number of World species recognized likely to be an order of magnitude too low, with tanaidaceans potentially matching the orders Amphipoda and Isopoda in diversity mainly in environments as deep waters (Błażewicz-Paszkowycz et al. 2012). The Brazilian Tanaidacea fauna is still poorly known, although recent papers have revised upwards the number of recorded species in the past twenty years (Santos and Hansknecht 2007;Larsen et al. 2009;Santos et al. 2012;Araújo-Silva et al. 2013;Segadilha et al. 2018;Segadilha et al. 2019).
Among coastal environments, rocky shores stand out for the high biodiversity of macroalgae, invertebrates, fish and seabirds, in addition to great ecological and economic importance (Messano et al. 2020). Rocky shore environments often cover large areas, although in Brazil they are almost exclusive to the southeast and south regions (Oigman-Pszczol et al. 2004), with the exception of the small rock formation present near the Cabo de Santo Agostinho, Pernambuco (Coutinho and Zalmon 2009). Thereby, the main part of the Brazilian coast where the rocky shores are among the most important ecosystems comprises Cabo Frio (Rio de Janeiro) to Cabo de Santa Marta (São Paulo) (Coutinho and Zalmon 2009). The order Tanaidacea, among other Peracaridans, has great importance associated with secondary biological substrates in rocky shores due to its high density and diversity of species (Edgar and Moore 1986).
The present study is part of the Project Rocky Shores: ecology, impacts, and conservation in the areas of Região dos Lagos and the north Fluminense, which aims to survey biodiversity, study the abundance and structure of invertebrate macrofauna communities and their correlations with environmental parameters in rocky shores of the northern part of Rio de Janeiro (Macaé, Rio das Ostras and Armação dos Búzios).

Material and methods
The Project Rocky Shores: ecology, impacts, and conservation in the areas of Região dos Lagos and the north Fluminense has been executed by the Institute of Biodiversity and Sustainability NUPEM/Universidade Federal do Rio de Janeiro with financial support of the Brazilian Biodiversity Fund (FUNBIO).
Five replicates were taken in each stratum, along 30 meters of extension on each shore. Sampling was made during low tides (≤ 0.2 m). The area of each sampled unit was delimited by a quadrat of 20x20 cm (0.04 m²) and samples were scraped with spatulas.
Specimens were sorted at the Laboratório Integrado de Biologia de Vertebrados, located in NUPEM/UFRJ. The algae were previously dipped and slightly agitated in buckets with water to remove the largest number of attached organisms, which were passed through a 1 mm mesh sieve. The material retained in the sieve (> 1mm) was separated, preserved in 70% ethanol and subsequently identified. The washed macroalgae and other larger organisms (e.g., sea urchins, bivalves) were carefully observed in stereomicroscope to search for attached organisms, which were also included and identified.
Drawings were made using a microscope Zeiss with a camera lucida and digitalized with WACOM Tablet using the program Adobe Illustrator CC 2017. The appendages were dissected using chemically sharpened tungsten-wire needles. Body length was measured from the tip of the rostrum to the tip of the pleotelson, and pereonite width at the broadest part. The length/width ratio was calculated from the measurements made in the middle length and width of an article. The measurements of cheliped articles and the morphological terminology follow that used by Błażewicz-Paszkowycz (2007). The articulated protrusions on the distal edge of the maxillipedal endites are called 'gustatory cusps' as proposed by Segadilha et al. (2018) (equivalent to 'cusps' sensu Bird and Larsen (2009). The maps illustrating the distribution of the described species were prepared using Quantum GIS v.2.16.3 Software.
The species Parapseudes hirsutus Stebbing, 1910 was reclassified by Sieg (1983) in the genus Apseudomorpha. However, Guţu (2009) indicated that the characteristics of the pereopods 1-3 (including the large number of the sternal spines on carpus and propodus), the great length of the antennule and the large number of the flagella segments, correspond to the genus Pseudoapseudomorpha. Yet, due to the absence of the cheliped description in Stebbing (1910), more specifically if the exopodite is present or not, Guţu (2009)
Pleotelson (Figs 1A, 2A, C) as long as pereonite-6 ( Fig. 2A); dorso-anteriorly with two tubercles, each with two simple setae ( Fig. 2A, C); antero-laterally with tubercle with round tip and bearing simple distal seta (Fig. 2C); prominent triangular apex with two sub-distal setae ( Fig. 2A, C). Antennule ( Fig. 3A) shorter than cephalothorax. Peduncle with four articles. Article-1 2.2 times L:W; inner margin with two simple sub-distal setae and one blunt apophysis; outer margin with one distal pointed angle, with one simple and three penicillate setae proximally, with one long and one short simple and two penicillate setae medially, and with three simple setae distally. Article-2 as long as wide; with seven simple and one penicillate setae distally. Article-3 just longer than wide; with two simple distal setae. Article-4 as long as wide; with two middle penicillate and one simple and one penicillate distal setae. Outer flagellum with three segments. Segment-1 slightly longer than wide, with middle and two distal simple setae and one aesthetasc. Segment-2 about 1.3 times L:W; distally with three simple setae and one aesthetasc. Segment-3 2.5 times L:W, distally with five simple setae, one penicillate, and one aesthetasc. Inner flagellum with one segment, 2.8 times L:W, distally with three simple and two penicillate setae. Antenna ( Fig. 3B) with eight articles. Article-1 inner margin with rounded distal process. Article-2 inner margin with penicillate seta and distal triangular apophysis; outer margin scaly with two penicillate setae; squama present, longer than article-3, with two distal simple setae. Article-3 wider than long; inner sub-distal margin with simple seta and apophysis. Article-4 inner distal margin with two penicillate setae. Article-5 about 1.3 times L:W, longer than article-4, with two simple and six penicillate setae. Article-6 half-length of article-5, with two simple distal setae. Article-7 longer than article-6, inner distal margin with two simple setae; outer distal margin with simple seta. Article-8 shortest, with three simple and two penicillate distal setae.
Maxilliped (Fig. 4B-C). Coxa short and wide. Basis finely setose with microtrichia, wider than long, with two denticles on outer distal margin. Palp article-1 shortest, distal inner margin with long (passing article-3) simple seta, and distal outer margin expanded distally with simple seta; article-2 longest, inner margin finely setulose proximally, with 14 simple setae, outer distal margin with strong spine; article-3 inner margin with eight simple setae; article-4 with six simple inner setae and two subdistal outer setae. Endite (Fig. 4B-C) with inner margin with seven basally-swollen setulate setae, four simple setae and four apically long simple setae; outer margin setulose with small denticles on mid margin.
Cheliped (Fig. 5A). Basis, 1.5 times L:W; ventral margin with distal simple seta. Merus triangular; ventral margin with three simple setae sub-distally. Carpus 2.7 times L:W, just longer than basis, widest distally; ventral margin with one middle and two sub-distal simple setae; dorsal margin with middle and sub-distal simple setae. Propodus 1.9 times L:W; with two simple setae near articulation of dactylus (one long and one small); fixed finger with three ventral simple setae, with five sub-marginal simple setae on outer incisive margin; inner face with sub-distal and mid-ventral simple setae. Dactylus and unguis slightly longer than fixed finger; inner face with simple seta on ventral margin.
Pereopod-1 (Fig. 6A). Coxa with two penicillate and four minute setae. Basis 3.6 times L:W; ventral margin with three penicillate and three simple setae, and one spine, one penicillate and one long seta distally; dorsal margin with seven penicillate setae. Ischium with penicillate and simple ventral seta. Merus 1.7 times L:W, widest distally; ventral margin with two simple setae and one sub-distal serrulate spine; outer margin with two middle setulate setae; distodorsal margin with simple seta and serrulate spine. Carpus as long as wide, widest distally, ventral margin with two simple setae and two serrulate spines; outer margin with middle setulate setae; distodorsal margin with penicillate, two simple setae and serrulate spine. Propodus 2.5 times L:W, ventral margin with four serrulate spines and simple seta; outer margin with middle setulate setae; dorsal margin with two penicillate, simple seta and two (one sub-distal and one distal) serrulate spines, and one sub-distal simple seta; inner face with long penicillate and two pectinate setae distally. Dactylus together with unguis shorter than propodus, dactylus longer than unguis; dactylus with two minute ventral setae and small sub-distal denticle. Unguis curved. Pereopod-2 (Fig. 6B) shorter and more gracile than pereopod-1. Coxa with two simple setae. Basis 3.8 times L:W; ventral margin with four simple setae and one long seta distally; dorsal margin with four simple setae. Ischium wider than long, with simple ventral seta. Merus 1.7 times L:W, widest distally; ventral margin with two simple setae and two sub-distal serrulate spines; outer margin with middle simple seta; distodorsal margin with simple seta. Carpus about as long as wide; ventral margin with four serrulate spines; distodorsal margin with four simple setae and two serrulate spines. Propodus 2.6 times L:W; ventral margin with four serrulate spines and two simple setae; dorsal margin with penicillate and two (one sub-distal and one distal) serrulate spines, and one sub-distal simple seta (longer than dactylus); inner face with two pectinate setae distally. Dactylus together with unguis shorter than propodus, dactylus longer than unguis; dactylus with two (one in the middle and one sub-distal) ventral setae and small sub-distal denticle. Unguis curved.
Pereopod-4 (Fig. 6D). Coxa with simple seta. Basis three times L:W; ventral margin with two simple and one distal setae; dorsal margin with two penicillate and three simple setae. Ischium wider than long, with two ventral setae. Merus 1.5 times L:W; widest distally; ventral margin with sub-distal simple seta and spine; outer margin with middle setulate seta; distodorsal margin with simple seta. Carpus 1.6 times L:W; ventral margin with two simple setae and four spines; distodorsal margin with five simple setae. Propodus 2.3 times L:W; ventral margin with two spines; outer margin with middle setulate seta; dorsal margin with penicillate seta, and sub-distal spine and simple seta; inner face with row of five sub-distal pectinate plus one long simple setae distally. Dactylus together with unguis shorter than propodus, dactylus longer than unguis; dactylus with two (one in the middle and one sub-distal) ventral setae and small sub-distal denticle. Unguis curved.
Pereopod-5 (Fig. 6E) similar to pereopod-4. Pereopod-6 ( Fig. 6F) similar to pereopod-5 but slightly smaller. Basis dorsal margin with two penicillate and two simple setae. Ischium with ventral setae. Merus  ventral margin with sub-distal simple seta; outer margin with middle setulate seta; distodorsal margin with simple seta. Propodus ventral margin with two spines and simple seta; outer margin with middle setulate seta; dorsal margin with penicillate seta, and sub-distal spine and two simple setae; distally with row of five pectinate and two simple setae. Pleopods (Fig. 7A). Five similar, biramous pairs. Basal article 5.8 times L:W, 2.4 times longer than both rami, naked. Exopod slightly longer than endopod, both uniarticulate and with long plumose seta distally. Uropod (Fig. 7B) biramous. Basal article 1.8 times L:W; inner margin with long distal simple seta; outer margin with one mid and two distal simple setae (one long and one small). Exopod of two segments, shorter than endopod segments 1-2 combined. Segment-1 with two simple distal setae. Segment-2 with two simple distal setae. Endopod shorter than pleon and pleotelson combined, with four segments. Segment-1 with two penicillate and one simple distal setae. Segments 2-4 about same length. Segment-2 with two penicillate and three simple setae on distal margin. Segment-3 with two penicillate and two simple distal setae. Terminal segment with one penicillate and four simple setae distally.
Adult male. Length 1.8 mm. Similar to females except in the size of the chelipeds (allotype and paratype: MNRJ 29864, MNRJ 29858, respectively). Cheliped (Fig. 5B) robust. Basis longer than wide, with one distoventral and two proximal simple setae. Merus with middle and two distoventral simple setae. Carpus broad and short; distoventral margin with a prolongation and three proximal setae. Propodus just wider than long; ventral margin with three simple setae; fixed finger short, with ten sub-marginal simple setae on outer incisive margin; dorsal margin with two denticles and grasping edge, claw short. Dactylus curved, ventral margin with mid-blunt apophysis and grasping edge with row of five thin spines.
Etymology. The name is dedicated to Brazil, the country where the species were collected. Type locality. Eulittoral zone of rocky shores at Santana Archipelago, Macaé, Rio de Janeiro, Brazil.
Distribution. This species was found exclusively at eulittoral zone on rocky shores (macroalgae bank) of Santana Archipelago, Macaé, Rio de Janeiro, Brazil, Southwestern Atlantic (Fig. 13).
Ecology. In total, 33 specimens of Apseudomorpha brasiliensis sp. nov. were found in eight of 60 quadrats (13.3%) collected at Santana Archipelago. This species was most abundant in the intermediate stratum (82%), however it was also found in the lower stratum (18%), being absent in the upper stratum. The substrate of the quadrats where the species was found was covered predominantly by articulated calcareous algae (Rhodophy-ta), covering a surface between 50-95% (average of 81% of the area). The intermediate stratum presented mainly Rhodophyta macroalgae, although brown algae Ochrophyta also occurred. The predominant Rhodophyta genera were Corallina, Jania and Arthrocardia, with other taxa such as Gracilaria, Hypnea, Pterocladiella and Plocamium. The lower stratum showed a greater coverage of brown algae, mainly of the genera Sargassum, Padina and Colpomenia.
The new species from Brazil closely resembles A. drummi by having antennule main flagellum with three segments, pereopod-1 carpus and propodus with two and four ventral spines respectively and pleopods with each rami having one long penicillate seta. The former, however, can be distinguished from A. drummi by: (1) antennule article-1 inner margin with one blunt apophysis (three apophyses in A. drummi); (2) mandible palp article-2 and article-3 with six and nine finely penicillate setae on inner margin respectively (five and eight in A. drummi); (3) pereopods 1-2 basis with several setae along ventral margin, except distally (maximum one in A. drummi); (4) uropod exopod shorter than endopod segments 1-2 combined (longer in A. drummi); and (5) uropod endopod with four segments (five in A. drummi). These comparisons and others are developed in a key to the species of Apseudomorpha, shown below.
Pleon (Figs 8A, 9A-B) about 0.08 times of TBL. Pleonites narrower than pereonite-6; all wider than long, similar in shape, but the width gradually narrower from pleonites 1-5; pleonites 1 and 5 with pair of lateral simple setae and pleonite-5 also with two pairs of dorsolateral simple setae.
Pleotelson (Figs 8A, 9A-B) about 0.8 times L:W, pentangular in dorsal view, with pair of lateral simple setae, pair of subdistal and distal penicillate and simple setae.
Antennule (Figs 9A, 10A) shorter than cephalothorax; three-articled. Article-1 3.3 times L:W, outer margin with middle and distal simple and seven penicillate setae; inner margin with two simple setae. Article-2 0.9 times L:W, with penicillate and two simple distal setae. Article-3 2.1 times L:W, with middle and six distal simple setae and subterminal aesthetasc.
Maxilliped (Fig. 10I). Bases fused proximally, each bearing simple seta at insertion of palp. Endites not fused, reaching distal margin of palp article-1, each with long pinnate outer seta and two big gustatory cusps in ventrodistal region. Palp article-1 naked; article-2 with four simple inner setae; article-3 with five simple inner setae; article-4 with six distal simple setae. Epignath not recovered.
Cheliped (Fig. 11A) attached via small sclerite. Basis short, slightly longer than wide. Merus with ventral simple setae. Carpus stout, 1.3 times L:W, with three simple ventral setae and mid-dorsal and dorsodistal simple setae. Propodus about as long as carpus, 1.7 times L:W, with one outer and three inner simple setae near dactylus insertion; fixed finger with two ventral setae, cutting edge with three setae and pointed claw; dactylus with three ventral setae and dorsal seta.
Etymology. Named in honor of Dr. Luciano Fischer (NUPEM/UFRJ) for his competent coordination of the Project Rocky Shores, together with his enthusiasm and passion for the marine world.
Type locality. Eulittoral zone of rocky shores at Areias Negras Beach, Rio das Ostras, Rio de Janeiro, Brazil.
Distribution. This species was found within a macroalgae bank of the eulittoral zone of rocky shores at Areias Negras Beach, Rio das Ostras, Rio de Janeiro, Brazil, Southwestern Atlantic (Fig. 13).

Ecology.
A total of seven specimens were found in only two of 56 quadrats (3.6%) collected at the Areias Negras Beach. The species occurred solely in the lower stratum. In the quadrats where the species was found, the substrate was mainly covered by the brown algae Sargassum (70% of the surface) and articulated calcareous algae Rhodophyta (20-25% of the surface).

Remarks. The genus
Pseudozeuxo is currently monotypic and includes P. belizensis (WoRMS, 2020b). Pseudozeuxo fischeri sp. nov. presents all the diagnostic characters of the genus. It is distinguished from P. belizensis by (1) pereopods 1-3 coxa with long seta about as half as long as basis; (2) pereopods 2-3 carpus with only seta ventrodistally (P. belizensis has seta and spine); (3) pereopods 4-6 propodus with two spines and one seta ventrally; (4) uropod endopod article-2 0.8 times as long as article-1 (P. belizensis with article-2 small, about 0.4 times as long as article-1) and exopod one-articled (P. belizensis is two-articled).   Charbeitanais and Haimormus are recorded from the Pacific Ocean (Hong Kong and Japan, respectively; Bamber and Bird 1997; Kakui and Fujita 2018) and Pseudozeuxo is restricted to the Atlantic Ocean, being now recorded from the Southwestern Atlantic, besides the Caribbean Sea (Belize; Sieg 1982). Pseudozeuxo belizensis is a shallow water species (0.5-3 m depth) occurring at upper stratum of middle intertidal zone on coral reef (Sieg 1982), a generally similar habitat to that of Pseudozeuxo fischeri.

Discussion
The apseudomorphs are predominantly a shallow-water group and the family Metapseudidae occurs mainly in the continental shelf <200 m (Błażewicz-Paszkowycz et al. 2012). Species of Pseudozeuxidae are typical from coastal water (to 18 m) (Sieg 1982;Bamber and Bird 1997;Kakui and Fujita 2018). Currently, there are regions whose shallow-water tanaidacean faunas are still under-researched. A study of the Tanaidacea from Australia, predominantly in shallow waters, has discovered an extremely high diversity, increasing the number of described species in 14 years from 16 in 1996 to 117 by 2010 (Błażewicz-Paszkowycz et al. 2012). In addition, despite rocky shores being well-known in comparison to the deep sea, there are few specific tanaidacean works from this environment (e.g. Greve 1968;Pires 1980;Masunari 1983;Bamber and Bird 1997;Riggio 2008;Bamber 2012;Esquete et al. 2012). Of these authors, only Pires (1980) studied the Brazilian Peracarida fauna from the intertidal zone, at Ubatuba, São Paulo, which recorded three tanaidacean species: Chondrochelia savignyi (Krøyer, 1842), Teleotanais sp. and Zeuxo coralensis.
The diversity of the tanaidaceans in certain ocean regions remains to be discovered, especially in Brazil where this group is still understudied (in rocky intertidal sites, shallow water sediment or deep sea environments). Both new species represent also new records to Southwestern Atlantic for the family Pseudozeuxidae (Pseudozeuxo fischeri sp. nov.) and for the subfamily Metapseudidae (Apseudomorpha brasiliensis sp. nov.). Thus, it is likely that further studies on the Brazilian coast would lead to the discovery of new species besides other new records.
Great advances have been made in the past twenty years to understand the Brazilian Tanaidacean fauna; however progress will continue to be restricted by the lack of tanaidacean taxonomists and researchers, but mainly by the lack of funding for this enterprise. Nevertheless, it is evident from our current knowledge that the Tanaidacea form a very diverse order of the Peracarida and are of considerable ecological significance in certain regions and habitats (Błażewicz-Paszkowycz et al. 2012), and future investments in this field should be considered.