Bol. Téc. Cient. Cepnor, v. 17, n. 1, p: 59 - 62, 2017 doi: 10.32519/tjfas.v17i1.2149 Boletim Técnico Cientifico do CEPNOR TROPICAL JOURNAL of Fisheries and Aquatic Sciences https://cepnor.ufra.edu.br/index.php?journal=tjfas&page=index NOTA CIENTÍFICA A new perspective on the distribution of chaetognatha, spadellidae, Paraspadella nana owre, 1963: two new occurrences from the western tropical atlantic ocean Lucas Guedes Pereira Figueirêdo1, Pedro Augusto Mendes de Castro Melo1, Gabriel Bitencourt Farias1, Mauro de Melo Júnior2, Xiomara Garcia Diaz3, Rodrigo Leão de Moura4 & Sigrid Neumann Leitão1 Departamento de Oceanografia, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil Departamento de Biologia, Universidade Federal Rural de Pernambuco, Recife, Pernambuco, Brazil 3 Instituto Socioambiental e dos Recursos Hídricos, Universidade Federal da Amazônia, Belém, Para, Brazil 4 Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil 1 2 E-mail: figueiredo@lgp.net.br Recebido em: 30/12/2017 - Aceito em 30/01/2018 - Distribuido em: 04/07/2018 ABSTRACT: Two new records of Paraspadella nana (Owre, 1963) are reported. The individuals were found in two distinct locations apart more than 1,000 km from each other (the Abrolhos Bank and the Tamandaré bay, Northeastern Brazil). Emergent traps for demersal zooplankton were used for the sample collection. This methodology is proposed as the most efficient to catch Spadellidae species and possibly changing the perspective on the distribution of this group. The finding reported here significantly expends the distributional range of P. nana in the Western Tropical Atlantic Ocean.. Keywords: Emergent trap, demersal zooplankton, benthic chaetognatha Uma nova perspectiva sobre a distribuição de Paraspadella nana Owre, 1963 (Chaetognatha, Spadellidae): duas novas ocorrências no Oceano Atlântico Tropical RESUMO: Dois novos registros de Paraspadella nana (Owre, 1963) são relatados. Os indivíduos foram encontrados em dois locais distintos, distantes mais de 1.000 km entre si (o Banco dos Abrolhos e a Baía de Tamandaré, Nordeste do Brasil). Armadilhas emergentes para zooplâncton demersal foram utilizadas para a coleta de amostras. Esta metodologia é proposta como a mais eficiente para capturar espécies de Spadellidae e possivelmente mudar a perspectiva sobre a distribuição deste grupo. A descoberta relatada aqui gasta significativamente o alcance da distribuição de P. nana no Oceano Atlântico Tropical Ocidental. Palavras-chave: Armadilha emergente, zooplâncton demersal, chaetognatha bentônico Introduction Chaetognaths play an important role in marine food webs, due to their active predatory behavior. In their diet are several pelagic organisms, consisting mainly of copepods, but they may also prey on other crustaceans and even fish larvae thus impacting the zooplankton and ictioplankton communities (Casanova 1999). Studies on chaetognaths in Brazil have concentrated on the abundant pelagic forms (Liang and Vega-Pérez 2001; Liang and Vega-Pérez 2002), which some times are surpassed in number only by copepods (Gusmão 1986). Not only in Brazil, but worldwide the pelagic communities of chaetognaths are better studied, and the distribution of the benthic forms such as the genus Paraspadella is poorly documented (Owre 1963). The family Spadellidae consists of 31 described species, all benthic and grouped in 5 genera. The genus Paraspadella was initially described by Salvini-Plawen (1986) and then combined with the genus Gephyrospadella by Bowman and Bieri (1989), grouping all the species that presented adhesive organs (main taxonomic feature of the genus Paraspadella). Currently, a total of 10 species compose the genus Paraspadella (Paraspadella anops Bowman and Bieri, 1989; P. caecafea (Salvini-Plawen, 1986); P. gotoi Casanova, 1990; P. johnstoni (Mawson, 1944); P. legazpichessi (Alvariño, 1981); P. nana (Owre, 1963); P. pimukatharos (Alvariño, 1987); P. pulchella (Owre, 1963); Paraspadella schizoptera (Conant, 1895); P. sheardi (Mawson, 1944). 59 Bol. Téc. Cient. Cepnor, v. 17, n. 1, p: 59 - 62, 2017 doi: 10.32519/tjfas.v17i1.2149 The species P. nana has very few occurrences reported. Owre made the first report in 1963 at the time he describe this species. A total of 15 specimens were collected from sediment samples associated with algae at Soldier Key, Florida. A new occurrence was reported by Arruda et al. (2010) at the Eastern Brazilian Continental Shelf (EBCS). In this occasion, a total of 3 specimens were collected by horizontal hauls (200 µm mesh net). This study reports two new occurrences of P. nana in Northeastern Brazil and gives a new perspective on its distribution in the Atlantic Ocean. Material and Methods The specimens were collected in two sampling areas apart more than 1,000 km from each other: (1) the Abrolhos Bank (17˚57’ S; 38˚ 42’ W); and (2) the Tamandaré bay (8˚ 45’’ S; 35˚ 05’’ W). The samples were collected using emergence traps according to the methodology proposed by Porter et al. (1977) to catch demersal zooplankton. The trap consists of a conical net (200 µm mesh) placed with the mouth directed to the substrate. This type of trap conducts vertically migrating animals through a conical-shaped region into a catch chamber. The traps were placed across hard substrate (coral reef) and soft substrate (sandy bottom). In Tamandaré Bay, the traps were placed only on reef substrate. A total of 24 samples were collected in the Abrolhos Bank and 30 samples were collected in Tamandaré Bay. After collection, the samples were fixed in 4% formalin/seawater solution. In the laboratory the samples were analyzed under stereoscopic microscope and the chaetognaths were sorted and identified based on descriptions of Owre (1963). Because of the sampling methodology (no stress by turbulence) the specimens of P. nana were in perfect condition (Fig. 1). The specimens are in accordance with the diagnosis proposed by Owre (1963), with the main characteristic features: (1) body relatively slender and rigid with a broader head; (2) there is 5 to 9 hooks and 1 to 3 anterior teeth depending on its maturity; (3) corona ciliata is variable in shape and situated on the anterior trunk; (4) A long collarette is present, being thickest at the neck and extending along the base of the lateral fin to the seminal vesicle; (5) There is one pair of lateral fins that originate anterior to the apertures of the seminal receptacles and terminate just anterior to the seminal vesicles. The caudal fin is broad and originates on the posterior face of the seminal vesicles; (6) A pair of adhesive organs is formed ventrally, from the posterior end of the lateral fins. Results and Discussion In the Abrolhos bank 12 specimens were collected, presenting a mean density of 17,8 ind. m-2. Figure 1. Paraspadella nana (Owre, 1963). Dorsal view of two specimens from Northeastern Brazil. The pairs of adhesive appendices can be seen on both sides at the tail region. Of the total specimens found in the Abrolhos Bank, 8 were collected on the coral reefs and 4 on the sandy bottom. In the Tamandaré bay, an overwhelming amount of 156 specimens were collected, presenting a mean density of 17 ind. m-2. Since the family Spadellidae is typically benthic, the occurrence of individuals of this family is scarce on studies of zooplankton. The methodology of collection in studies of zooplankton is generally based on pelagic hauls that may catch Spadellidae individuals only in case of occasional resuspension of sediments due to local currents (Arruda et al. 2010). Species of this genus have one reported occurrence in usual plankton collections (Arruda et al. 2010). Benthic collections may also fail to report the occurrence of these species, because they usually overlook these animals due to their small size (Alvariño 1981). Among the Spadellidae members, the individuals of Paraspadella genus have even more limited distribution because of their restricted habitat and movements (Alvariño 1981). However, with proper sampling, new perspectives on the distributional range of species of Paraspadella may be obtained. Studies of demersal zooplankton (i.e. fauna that live in close association with the benthic domain during the day and migrate into the overlying water column at night) report more frequent occurrences of Spadellidae individuals. Several authors describe these animals as demersal zooplankters (Alldredge and King 1977; Jacoby and Greenwood 1989; 60 Bol. Téc. Cient. Cepnor, v. 17, n. 1, p: 59 - 62, 2017 doi: 10.32519/tjfas.v17i1.2149 Madhupratap et al. 1991). Alldredge and King (1977) collected individuals of Paraspadella in large numbers from several substrate types using emergent traps at the Great Barrier Reef as well as Jacoby and Greenwood (1989) which reported the occurrence of a species of the genus Spadella in Queensland, Australia. Madhupratap et al. (1991) using emergent traps in the archipelagos off the western coast of India reported the occurrence of Spadella angulata in densities similar to that reported here for P. nana. The distribution of P. nana and other Spadellidae species might not be as restricted as expected. The methodology commonly used for sampling and analysis of samples in studies of zooplankton and benthic communities may not be the most efficient to catch demersal chaetognaths. According to the findings of Kramer et al. (2013), the benthic and the demersal communities may be significant distinct. Kramer’s work compared the benthic fauna and the emergent assemblages of the same substrate and showed that 32% of the taxa captured by the emergent traps were absent from the benthic community. This is probably because these demersal taxa arise from a rich variety of structural features found in the reef matrix that are not properly sampled by benthic and zooplankton collections. Moreover, Paraspadella emerge primarily from coral, rubble and rock in reef areas (Alldredge and King 1977). This communication furnishes the report of the occurrence of the rare P. nana in two distinct areas and in numbers never caught before, with the use of emergent traps. This new report expends the distribution of P. nana, which now has a wider range of occurrence reported for the western tropical Atlantic (Fig. 2). ACKNOWLEDGEMENTS We would like to thank CAPES and CNPq (PROABROLHOS) for their financial support. This paper is a contribution of the Rede Abrolhos (Abrolhos Network – www.abrolhos.org) funded by CNPq/ CAPES/FAPES/FAPERJ (programs SISBIOTA and PELD). We would also like to thank the Federal University of Pernambuco and the post-graduation program of Oceanography (PPGO-UFPE). Figure 2. Geographic distribution of Paraspadella nana (Owre, 1963). Circles – previous records; stars – New records. References Islands. Proc Biol Soc Wash 94: 107-121. 1981. ALLDREDGE, A. L.; KING, J. M. 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