Description of Sidneioides peregrinus sp. nov. (Tunicata: Ascidiacea: Polyclinidae): a possible exotic species in the Atlantic Ocean

Abstract

Three species of Sidneioides Kesteven, 1909 were known until now, all of them from the western Pacific. Sidneioides peregrinus is a new species we found in Paranaguá Bay, southern Brazil. Diagnostic characteristics of the species are: colonies with 1-5 lobes, closely clumped, and attached by the entire basal area or by a common smaller area; seven to ten thin longitudinal fiber muscles (some branched) along the anterior two thirds of the thorax; no transverse muscle fibers; more than 30 tentacles of three orders forming one circle; pharynx with 10 to 12 rows of stigmata with 13 to 15 stigmata in each half row; bilobed anus at the level of the fourth or fifth row of stigmata; posterior abdomen not very elongated, oval, and joined to the abdomen by a narrow neck; numerous (> 30) testicular follicles; ovary with about 15 oocytes at about the ninth or tenth row of stigmata in the thorax; large number of embryos incubated in the atrial cavity in the right side of the thorax; larvae oval with a 0.65 mm long trunk, four club-shaped ectodermal ampullae in each side and three, linear and evenly spaced, adhesive papillae with thin stalks, two clusters of ectodermal vesicles, one postero-ventral (around 15 vesicles) and another antero-dorsal (around eight vesicles) between the ampullae and the oral siphon. This paper describes this new species and reports its occurrence in Brazil, where it is most likely introduced. The hypothesis that it is introduced is based on 1) it was never found in previous surveys, 2) in Brazil, it has a restricted and local distribution, 3) its type locality is near a major international port, and 4) the genus, prior to this description, had never been found in the Atlantic Ocean. Considering the great abundance found on the underside of natural boulders, it is imperative that S. peregrinus population growth be studied to evaluate the possibility of rapid distribution expansion

Invading the natural marine substrates: a case study with invertebrates in South Brazil

“…Three species occurred only in artificial substrata, the ascidian Ascidia tenue (Monniot, 1983), the barnacle Balanus trigonus Darwin, 1854 and the polychaete Polydora cornuta Bosc, 1802. One NIS was exclusively found on natural substrata, the ascidian Sidneioides peregrinus Kremer, Metri & Rocha, 2011 (Table 1). Four NIS are reported here for the first time in natural substrata in the region, the octocoral Carijoa riisei (Duchassaing & Michelotti, 1860), the hydrozoan Garveia franciscana Torrey, 1902, the barnacle Striatobalanus amaryllis Darwin, 1954 and the bivalve Myoforceps aristatus (Dillwyn, 1817) (also known as Lithophaga aristata and Leisolenus aristatus).…”

Detection of introduced sessile species on the near shore continental shelf in southern Brazil

“…The number of introduced species has continued to rise since that study. Some species probably arrived later as they were first found only after the year 2000: the hydrozoan G. franciscana, the octocoral Stragulum bicolor ( VAN OFWEGEN & HADDAD 2011), both found in this study, and the tunicate Sidneioides peregrinus (KREMER et al 2011). A greater understanding of the historical distribution of the organisms also lead to reclassification, increasing the number of introduced species: the barnacles previously considered cryptogenic A. amphitrite and B. trigonus (CANGUSSU et al 2010) are now considered introduced here (CARLTON et al 2011).…”