New species of Temnocephala (Platyhelminthes, Temnocephalida) ectosymbiont on vulnerable species of aeglids (Crustacea, Anomura) from the Neotropical Region

Abstract

SEIXAS, S.A., DAMETTO, N., PÉRICO, E. New species of Temnocephala (Platyhelminthes, Temnocephalida) ectosymbiont on vulnerable species of aeglids (Crustacea, Anomura) from the Neotropical Region. Biota Neotropica. 18(4): e201704725. http://dx.doi.org/10.1590/1676-0611- BN-2017-0475 Abstract: A new species of the genus Temnocephala Blanchard, 1849 from southern Brazil was found on two species of anomuran crustaceans, Aegla spinipalma Bond-Buckup & Buckup, 1994 and Aegla grisella Bond-Buckup & Buckup, 1994, the latter classified as a vulnerable species by the "Lista de Referência da Fauna Ameaçada de Extinção no Rio Grande do Sul. Decreto no 41.672, de 11 junho de 2002". The crustaceans were collected from a tributary creek of the Forqueta river, Perau de Janeiro, Arvorezinha and a tributary creek of the Fão river, Pouso Novo, Rio Grande do Sul, Brazil; both localities belong to the Sub-Basin of Forqueta River. The new species differs from seven other temnocephalans epibionts on Aegla Leach, 1820, by having the following characters: 1. a long and slightly curved cirrus, 2. two vaginal sphincters, one proximal, big and asymmetric, and one distal, smaller and symmetric, and; 3. longer than wide, elongated epidermal 'excretory' syncytial plates (EPs), with a almost horizontally central excretory pore, displaced to the anterior portion of the plate. The new species' EP is the largest in total length among epibionts temnocephalans in crustaceans already registered. Regarding the similarities with the male reproductive system of Temnocephala axenos Monticelli, 1898, the new species has important differences in the female reproductive system. It has a larger proximal vaginal sphincter, located in the middle of the vagina, while the smaller distal one is at the extreme end of the organ. Besides that, the vaginal portion between the proximal and distal sphincters is conspicuous, with a strong muscular wall. This is the first record of a species of Temnocephala in the Taquari Valley, as well in the 'Perau de Janeiro', which is an area with a rich endemic fauna. Keywords: crustacean, ectosymbiont, South America, symbiosis, Taxonomy. Nova espécie de Temnocephala (Platyhelminthes, Temnocephalida) ectosimbionte sobre espécies vulneráveis de eglídeos (Crustacea, Anomura) da Região NeotropicalResumo: Uma nova espécie do gênero Temnocephala Blanchard, 1849 da região sul do Brasil foi encontrada sobre duas espécies de crustáceos anomuros, Aegla spinipalma Bond-Buckup & Buckup, 1994 e Aegla grisella Bond-Buckup & Buckup, 1994, a última classificada como uma espécie vulnerável pela Lista de Referência da Fauna Ameaçada de Extinção no Rio Grande do Sul. Decreto no 41.672, de 11 junho de 2002. Os crustáceos foram coletados em um arroio tributário do Rio Forqueta, Perau de Janeiro, Arvorezinha e em um arroio tributário do Rio Fão, Pouso Novo, Rio Grande do Sul, Brazil; ambas localidades pertencem a Sub-Bacia do Rio Forqueta. A nova espécie se diferencia dos outros sete temnocefalídeos epibiontes sobre Aegla Leach, 1820 pelos caract...

OnTemnocephala axenosMonticelli, 1898 (Platyhelminthes, Temnocephalida): taxonomic status and designation of a neotype

“…Temnocephala grisella has the largest EP in total length among the epibionts of aeglids, but the total body length/EPs length ratio is similar between both species (6.7:1 in T. grisella and 7:1 in T. axenos). However, the shape described as 'elongate, wider in the area surrounding the excretory pore' by Seixas et al (2018) differs from the elliptical-rectangular shape with marked and less bulged front and rear edges presented in T. axenos. The EPs of T. grisella are also thinner than the EPs of T. axenos, as we can see when comparing the total body width/ EPs width ratio (14:1 in T. grisella and 11:1 in T. axenos).…”

“…However, the shape described as ‘elongate, wider in the area surrounding the excretory pore’ by Seixas et al . (2018) differs from the elliptical–rectangular shape with marked and less bulged front and rear edges presented in T. axenos . The EPs of T. grisella are also thinner than the EPs of T. axenos , as we can see when comparing the total body width/EPs width ratio (14:1 in T. grisella and 11:1 in T. axenos ).…”

“…Temnocephala grisella, T. gargantua and T. cyanoglandula present a long and slightly curved cirri. Although similar to T. axenos in shape, the cirrus is much longer in the three species (202 μm on average in T. grisella, 225 μm on average in T. gargantua and 256 μm on average in T. cyanoglandula) (Amato et al, 2003;Seixas et al, 2015aSeixas et al, , 2018; Ponce de León & Volonterio, 2018).…”

“…They occur on freshwater hosts, particularly crustaceans, but also molluscs, insects and turtles. Nine valid species of the genus Temnocephala Blanchard, 1849 were recorded on species of Aegla Leach, 1820 (Crustacea, Anomura, Aeglidae): Temnocephala chilensis (Moquin-Tandon, 1846), Temnocephala axenos Monticelli, 1898, Temnocephala mexicana Vayssière, 1898, Temnocephala talicei Dioni, 1967, Temnocephala cyanoglandula Amato, Amato & Daudt, 2003, Temnocephala mertoni Volonterio, 2007, Temnocephala dionii Ponce de León, Berón Vera & Volonterio, 2015, Temnocephala grisella Seixas, Dametto & Périco, 2018 and Temnocephala gargantua Ponce de León & Volonterio, 2018 (Ponce de León & Volonterio, 2018; Seixas et al ., 2018).…”

A new flatworm species of Temnocephala (Rhabdocoela, Temnocephalidae) ectosymbiont on the freshwater crab Valdivia serrata (Decapoda, Trichodactylidae) from Amazonas, Colombia

“…The genus Temnocephala Blanchard, 1849 includes 37 species of symbiotic freshwater rhabdocoels from the Neotropics, which are associated with a large variety of hosts including chelonians (3), mollusks (6), insects (7) and crustaceans (21) (Garcés et al 2013, Martínez-Aquino et al 2014, Arias-Pineda et al 2015, Seixas et al 2015a, Ponce de León and Volonterio 2018, Seixas et al 2018. At present, only two species have been described from Colombia, T. colombiensis Garcés, Puerta, Tabares, Lenis & Velásquez, 2013, ectosymbiont of the gastropod Pomacea sp., and T. icononcensis Arias-Pineda, Damborenea & Castro, 2015, hosted by the pseudothelphusid crabs Hypolobocera bouvieri (Rathbun 1898), Phallangothelphusa dispar (Zimmer 1912) and Strengeriana cajaensis Campos & Rodríguez, 1993.…”