RESUMO
Abstract Mytilopsis leucophaeata is an estuarine bivalve native from the Gulf of Mexico and Southeast USA, and it was introduced in Europe, Asia, Caribbean, South America and Northeast USA, showing massive colonization skills. In Brazil, the single invasion records of M. leucophaeata occur in the city of Rio de Janeiro, i.e., in the Rodrigo de Freitas Lagoon and in the Marapendi Lagoon. We conducted a new series of fieldworks in estuaries from the Rio de Janeiro state in order to evaluate the propagation of this invasive bivalve, aiming sites with proper salinities for the establishment of M. leucophaeata. A new record is given for the Maricá-Guarapina lagoon system, where M. leucophaeata mainly colonizes hard substrata (such as piers and rocks), reaching a mean density up to 43,375 specimens/m2; however, aggregates of M. leucophaeata were also observed in the soft substratum. Based on mitochondrial sequences, the taxonomic identification of the invasive bivalve was confirmed. The associated fauna to the agglomerates of M. leucophaeata in the lagoon system comprises amphipods, barnacles, tanaidaceans, isopods, crabs, polychaetes and snails. The expansion of M. leucophaeata requires a continuous investigation due to the great circulation of boats in the littoral of the Rio de Janeiro state and the increased chance of new introductions.
Resumo Mytilopsis leucophaeata é um bivalve estuarino originário do Golfo do México e Sudeste dos EUA, tendo sido introduzido na Europa, Ásia, Caribe, América do Sul e Nordeste dos EUA, e apresentando massiva capacidade de colonização. No Brasil, os únicos registros de invasão de M. leucophaeata ocorrem no município do Rio de Janeiro, i.e., na Lagoa Rodrigo de Freitas e na Lagoa de Marapendi. Este estudo propõe um novo levantamento de campo em estuários fluminenses para avaliar a propagação desse bivalve invasor, visando locais com salinidade propícia para o estabelecimento de M. leucophaeata. Um novo registro é feito para o complexo lagunar Maricá-Guarapina, onde M. leucophaeata coloniza principalmente substratos duros (como píers e rochas), chegando a uma densidade média de 43.375 indíviduos/m2; porém, agregados de M. leucophaeata também foram observados em substrato inconsolidado. Com base em sequências mitocondriais, a identificação taxonômica do bivalve invasor foi confirmada. A fauna associada aos aglomerados de M. leucophaeata no complexo lagunar compreende anfípodes, cracas, tanaidáceos, isópodes, caranguejos, poliquetas e gastrópodes. A expansão de M. leucophaeata demanda uma investigação contínua devido ao alto fluxo de embarcações no litoral fluminense e elevada probabilidade de novas introduções.
RESUMO
The triphorid genera Inella and Strobiligera are historically considered to represent one or two distinct groups, with recent studies claiming that Strobiligera comprises species with paucispiral or multispiral protoconchs, whereas only species with paucispiral protoconch occur in Inella. The present study aims to update the taxonomy of Inella and Strobiligera (with paucispiral protoconchs) from Brazil. Three main groups are recognized: Inella s.s. and Strobiligera show a simultaneous emergence of the three spiral cords of the teleoconch, the former possessing a discrete nucleus and the latter bearing a distinct globose protoconch; the "pseudo Inella" group has a late emergence of the median spiral cord of teleoconch. Four species were previously recorded from Brazil: I. unicornium, I. longissima, S. pompona and S. compsa, of which the three latter records are disregarded for being based on shells with broken apices and consequent uncertainty of identification. Twenty species in fact occur in Brazil: Inella s.s. is represented by I. apexbilirata and one possible new species; "pseudo Inella" includes "Inella" differens, "Inella" faberi, "Inella" galo sp. nov., "Inella" euconfio sp. nov., "Inella" leucocephala sp. nov., "Inella" faceta sp. nov., "Inella" maculata sp. nov., "Inella" vanilla sp. nov., and three possible new species; Strobiligera is represented by S. unicornium comb. nov., S. gaesona, S. dinea, Strobiligera campista sp. nov., Strobiligera santista sp. nov., and two possible new species. The "pseudo Inella" group is probably derived from unrelated lineages that converged to a simple type of paucispiral protoconch, requiring the examination of radular morphology to properly reallocate those species. The supposed restricted geographical range of triphorids with lecithotrophic development requires future investigations of the five species from the northwestern Atlantic/Caribbean that are herein recorded to Brazil. Key words: Triphoroidea, marine molluscs, lecithotrophic development, western Atlantic Introduction Triphoridae is a speciose family of marine snails that feed on sponges, with 642 Recent valid species (WoRMS 2018) and hundreds of undescribed species (Albano et al. 2011). The genus Inella Bayle, 1879 is one of the most challenging taxa in Triphoridae, especially because of its uncertain taxonomic limits and high number of described species (Marshall 1983). Inella and Strobiligera Dall, 1924 are historically considered to represent one or two distinct groups, with recent studies claiming that Strobiligera comprises species with paucispiral or multispiral protoconchs, whereas only species with paucispiral protoconchs occur in Inella (Fernandes Pimenta 2014). A brief taxonomic overview of this issue will be addressed in the next lines.Hinds (1843) proposed the name Ino (preoccupied by the crustacean genus Ino Schrank, 1803; Inella Bayle is a replacement name) for cylindrical, elongated and acuminated triphorid shells. Jousseaume (1884) added that the shell of Inella is composed of at least 15 whorls, sculptured by spiral tubercles, with the last whorl presenting a depressed base and two apertures (i.e., the true aperture and the anterior canal). Laseron (1958) recognized that the Inella concept of Hinds (1843) mixed different shell types; however, Laseron broadened the definitions of Inella, as he also stated, warning that the use of protoconchs could need further generic revision. Kosuge (1966) defined Inella as having axial sculpture and three spiral cords on the teleoconch, a blunt and dome-shaped protoconch with a few spiral ridges, and suggested that Inella belongs to the most advanced group of triphorids. Marshall (1983) proposed the distinction between the "Triphora group" and the "Inella group" (composed of Inella Bayle and related genera) in Triphorinae, perhaps worthy of subfamily distinction, although this division is still informal (Marquet 1996). Marshall (1983: 19) also applied the term Inella s.l., recognizing that it contains "a number of natural groups that are worthy of genus-group status, most of which are as yet unnamed". Simone (2006) interpreted Inella as triphorids with a very elongated shell, a relatively straight spire profile and a projected aperture. Rolán Fernández-Garcés (2008) followed the concept of the catch-all taxon Inella s.l., uniting several species with very different shell forms under a more or less classical protoconch of Inella (i.e., without axial sculpture). Fernandes Pimenta (2014) recognized that lecithotrophic species of Strobiligera have a very inflated protoconch (following Dall 1924), which is distinct from the reduced nucleus observed in Inella s.l., thus substantially reducing the number of species from the Atlantic Ocean previously allocated to the latter. Marshall (1983) did not indicate any junior synonym for Inella, but Rolán Fernández-Garcés (2008) placed the type species of Strobiligera within Inella, which was later rejected by Fernandes Pimenta (2014). Marquet (1996: 141) mentioned that "Marshall (1983) placed Norephora in synonymy with Inella"; this is not true, as Marshall (1983: 81) only indicated that "Norephora is probably closely related to Inella Bayle" when compared with Talophora Gründel, 1975. In fact, Fernandes Pimenta (2014) suggested that Norephora is probably a synonym of Subulophora Laseron, 1958, pending further investigation. Wenz (1938 apud Kosuge 1966) suggested that Tristoma Menke, 1830 and Biforina Bucquoy, Dautzenberg Dollfus, 1884 were synonyms of Inella, but Marshall (1983) stated that the first is a synonym of Triphora Blainville, 1828 and the second is a synonym of Monophorus Grillo, 1877.Although many species remain to be described in these genera, Inella and Strobiligera are represented altogether by 64 Recent species worldwide (Bouchet Rosenberg 2013; Bouchet Gofas 2014). Both genera are particularly common in mid-low depths of the continental shelf and in the continental slope, especially Strobiligera (Fernandes Pimenta 2017a). Species with paucispiral protoconchs in both groups are absent from the eastern Atlantic (e.g., Bouchet 1985; Rolán 2005), although well-represented in the western Atlantic, with 27 Recent species (Simone 2006; Rolán Fernández-Garcés 2008), mainly in the Caribbean and adjacent regions. Only four of these species were reported from Brazil: Inella unicornium Simone, 2006 is the only endemic species of this genus in Brazil; Strobiligera compsa (Dall, 1927) and Strobiligera pompona (Dall, 1927) were respectively considered misidentifications of Absalão (1989) and Rios (1975, 1985, 1994, 2009) by Fernandes Pimenta (2014); and Inella longissima (Dall, 1881), reported by Rios (1985, 2009) from southern Brazil, replacing his prior identification of Inella triserialis Dall, 1881 (Rios 1975).The main objective of the present work is to update the taxonomy of Inella and Strobiligera species with paucispiral protoconchs, given that Strobiligera species from Brazil with multispiral protoconchs were already reviewed by Fernandes Pimenta (2014), filling a large gap in taxonomic knowledge.