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Temnocephala trapeziformis sp. nov., ectosymbiont on Trichodactylus fluviatilis Latreille, 1828 is described from the State of Rio Grande do Sul, southern Brazil. Sixty-eight crabs were examined, of which 61 (89.7 %) were positive for this species of the genus Temnocephala Blanchard, 1849. Eggs, as well as adult and young specimens, were found on the pleural areas of the carapace, in the orbital cavities, and, usually, on the fourth pair of pereiopods. The temnocephalans were always devoid of body pigmentation, although they kept the red eye pigment, undiluted in specimens fixed by hot (90ºC) phosphate buffered 10% formalin. The most distinctive characters of the new species are: 1) the shape and size of the cirrus and the characteristics of its introvert section; 2) the trapezoidal shape of the dorsolateral post-tentacular 'excretory' epidermal syncytial plates, with the nephridiopore in the lower inner corner of the plate; and 3) the number, size, and distribution of the rhabdite producing glands, as observed in very young specimens.

ABSTRACT. Temnocephala minutocirrus sp.sp. sp. sp. sp. nov nov nov nov nov. . . . ., an ectosymbiont on Cryphocricos granulosus De Carlo, 1967, is described from the State of Rio Grande do Sul, southern Brazil. One hundred and nine naucorids were examined, of which 36 (33%) were positive for this species of Temnocephala Blanchard, 1849. In one sample of 94 creeping water bugs, 49 (52%) were 4 th instar nymphs, 6% of which were infested; 45 (48%) were adults, either brachypterous (40 with 18 males and 22 females) or macropterous (5 with 1 male and 4 females), 67% of which were infested (29% males and 38% females). Temnocephalan eggs were found both ventrally and dorsally: fixed on coxae, trochanters, and along the sternum between fore middle, and hind pairs of legs; basal of the abdominal area; and on the scutellum, clavus, and hemelytra. Juvenile and adult temnocephalans were always devoid of body pigmentation, and were found living on the ventral body surface, preferably over the sternum, between the middle and hind pairs of legs. The most distinctive features of this new species are: 1) unusually short cirrus, slightly curved, with introvert corresponding to 37% of its total length; 2) dorsolateral 'excretory' syncytial epidermal plates, elliptic, with excretory pore relatively equatorial, closer to inner limit of each plate; 3) two pairs of large disc gland cells (paranephrocytes?) located centrally, just ahead of testes; 4) testes relatively large, but unequal in size, anterior pair smaller, always in the same zone, those of the same side, partially superposed; and (5) vagina with weak muscular wall and without muscular sphincters.

Temnocephala iheringi Haswell, 1893 was recorded in Marisa planogyra Pilsbry, 1933 and Pomacea maculata Perry, 1810. Also, Temnocephala amatoi sp. nov. was described from Pomacea scalaris (d’Orbigny, 1835). The mollusks were collected from temporary ponds at Ypiranga Farm, Poconé, Mato Grosso, Brazil. The new species differs from six other species of Temnocephala Blanchard, 1849 epibionts on molluks by having the following combination of characters: 1. a short and curved cirrus; 2. a narrow introvert with approximately 22 longitudinal rows of spines with 13 spines each; 3. internal spines with a narrow base, longer on the base of the introvert and smaller in the distal portion; 4. a single and asymmetrical vaginal sphincter and; 5. elliptical, longer than wide epidermal ‘excretory’ syncytial plates (EPs) with a excretory pore displaced to the anterior portion of the plate. Temnocephala lamothei Damborenea & Brusa, 2008 has a curved cirrus, similar in size to the new species’ cirrus. However, the introvert is not swollen with an oblique proximal margin, marked with a thickened oblique ring and two rows of 45–50 thin spines, differentiating the species from T. amatoi sp. nov.. When comparing the specimens of T. iheringi from Poconé with the redescription of the species from Southern Brazil previously published by the authors, we found significant intraspecific variation in the size of the adhesive disk, pharynx length, shaft and introvert length, spines of the introvert length, as well as differences in the number of paranephrocytes. The size of the EPs and, when comparing with published data from Uruguayan and Argentinean specimens, the body size also showed important differences. We hypothesize that the host species may be the cause of the intraspecific variations found. Overall, the record of two new hosts for T. iheringi, the intraspecific variation found in this species and its geographical distribution being expanded 418 km further to the north, together with the description of a new species, add acknowledgment to the Rhabdocoela fauna in the Brazilian Pantanal.

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...

Temnocephala lutzi Monticelli, 1913, ectosymbiont on brachyuran freshwater crabs of the genus Trichodactylus Latreille, 1828 is recorded for the first time in the State of Rio Grande do Sul, southern Brazil. Two hundred and seventy-nine crabs of two species were examined: 211 Trichodactylus panoplus (von Martens, 1869) and 68 Trichodactylus fluviatilis Latreille, 1828 of which 51 (24.17%) and 28 (41.17%) were positive for T. lutzi, respectively. Crabs of both species carried eggs fixed, exclusively, on the floor of the branchial chambers and/or on the lower side of the gills. Adult as well as young specimens were found inside and outside the branchial chambers. The temnocephalans were always devoid of body pigmentation, although they kept the red eye pigment undiluted in specimens fixed by formalin. The cirrus of T. lutzi showed the typical shape for the species, while the dorsolateral, post tentacular 'excretory' syncytial plates, demonstrated by two special techniques (silver nitrate staining and SEM), appeared with an elliptical shape and a central nephridiopore.

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The presence of adult specimens and eggs of Temnocephala pignalberiae Dioni, 1967 in Dilocarcinus pagei Stimpson, 1861, at Poconé, Brazilian ‘Pantanal’, State of Mato Grosso, together with abundant material also collected from D. pagei at Bebedouro, State of São Paulo, are reported. These two records allowed the extension of the known geographical distribution of T. pignalberiae from Argentina to Central Brazil, and the comparison of the temnocephalan infrapopulations from two allopatric crab populations, living approximately 1,300 km apart from each other. The entire sample from Poconé and part of the sample from Bebedouro were fixed according to our protocols. Juvenile and adult temnocephalans were whitish to light pink and presented the typical red-eye pigmentation. The worms were living in the branchial chambers, where they deposited their eggs, over the tissue covering the inner upper part of the carapace. These eggs were thin-shelled and the most delicate, so far recorded, for any temnocephalan species our group has studied. The most distinctive features of the temnocephalan specimens from the two localities representing different watersheds were the: 1. cirrus with unarmed introvert; 2. prostatic bulb thick-walled; 3. body ellipsoid, with small and more separate tentacles; 4. syncytial plates elongated and with similar shape; and 5. excretory pores in the same position inside the each syncytial plate. Differing minimally by the: 1. contrasting shaft bases – specimens from Poconé, with rims of the shaft base directed inward, while specimens from Bebedouro, with straight and more open shaft base rims, similar to the shaft bases drawn based on specimens found in Argentina; and 2. ratio between cirrus length and prostatic bulb length, resulting in longer prostatic bulbs in the specimens from Bebedouro. Statistical analysis of measurements taken from flattened adult specimens from the infrapopulations of the two localities showed only minimal differences in the length and width of some organs. This is expected to occur when the same species is collected from populations of the same host species living far from each other and representing separate watersheds.