An Acad Bras Cienc (2020) 92(2): e20180499 DOI 10.1590/0001-3765202020180499 Anais da Academia Brasileira de Ciências | Annals of the Brazilian Academy of Sciences Printed ISSN 0001-3765 I Online ISSN 1678-2690 www.scielo.br/aabc | www.fb.com/aabcjournal BIOLOGICAL SCIENCES A new species of Cosmocercoides Running title: NEW SPECIES OF Cosmocercoides IN Leptodactylus latrans (Nematoda; Cosmocercidae) and other helminths in Leptodactylus latrans (Anura; Academy Section: Health Sciences Leptodactylidae) from Argentina e20180499 REGINA DRAGHI, FABIANA B. DRAGO & LÍA I. LUNASCHI Abstract: Cosmocercoides latrans n. sp. (Cosmocercidae) from the small intestine of 92 (2) Leptodactylus latrans (Anura: Leptodactylidae) from Northeastern Province of Buenos 92(2) Aires, Argentina is described. The new species can be distinguished from their congeners by a combination of the characters, among which stands out the number of rosette papillae, the lack of gubernaculum and the presence of lateral alae in both sexes. There are over 20 species in the genus Cosmocercoides, and Cosmocercoides latrans n. sp. represents the third species from the Neotropical realm and the second for Argentina. Additionally, seven previously known taxa are reported; Pseudoacanthocephalus cf. lutzi, Catadiscus uruguayensis, Rauschiella palmipedis, Aplectana hylambatis, Cosmocerca parva, Schrankiana sp. and Rhabdias elegans; providing literature records and information on distribution and host-parasite relationships. Key words: helminths, Leptodactylus latrans, Cosmocercoides latrans n. sp., anura, Argentina. INTRODUCTION Venezuela, the savanna areas of Guyana, Brazil, northeastern Bolivia, eastern Paraguay, Previous reports of endoparasites in Argentina, and Uruguay (Heyer et al. 2010). Being Leptodactylus latrans (Steffen, 1815) have been an opportunistic feeder, its diet is generalist summarized in checklists from South America and determined by the availability of prey in the (Campião et al. 2014, Fernandes & Kohn 2014) environment (Duellman & Trueb 1994). and Argentina (González & Hamann 2015). Among nematodes, is frequent to find These reports, mainly as isolated records of a specimens belonging to Cosmocercidae. taxonomic nature, include several species of Members of this family are parasites of the acanthocephalans, digeneans, cestodes and digestive tract of amphibians and reptiles. It nematodes parasitizing this large frog species. includes the Subfamily Cosmocercinae Railliet, The criolla frog, as it is commonly known, 1916 that contains 9 genera: Cosmocerca inhabits flooded fields and temporary or Diesing, 1861, Aplectana Railliet & Henry, permanent shallow ponds and is also common 1916, Oxysomatium Railliet & Henry, 1916, to fi nd in periurban places and crops. It is widely Cosmocercella Steiner, 1924, Raillietnema distributed in South America, being present Travassos, 1927, Oxyascaris Travassos, 1920, in Trinidad and Tobago, Colombia, southern Cosmocercoides Wilkie, 1930 Paradollfusnema An Acad Bras Cienc (2020) 92(2) REGINA DRAGHI, FABIANA B. DRAGO & LÍA I. LUNASCHI NEW SPECIES OF Cosmocercoides IN Leptodactylus latrans Baker, 1982 and Neocosmocercella Baker & and the range in parentheses. The values of Vaucher, 1983 (Bursey et al. 2011). prevalence, mean intensity and intensity of The genus Cosmocercoides includes infection were calculated following the criteria species that commonly parasitize amphibians given by Bush et al. (1997). and reptiles, but also occasionally occur in land For scanning electron microscopy (SEM), snails and slugs (Chen et al. 2018). The aims helminths were dehydrated in a series of of the present work are (1) to describe a new alcohols (70 °, 80 °, 90 °, 95 ° and 100 °), species of Cosmocercoides and (2) to increase dried by the critical point method (Baltec CP- the knowledge of the diversity of helminths 30), metallized with a gold-palladium bath parasites of the Criolla frog, L. latrans. (Metallizer: JEOL Finecoat ion spputer JFC1100) and then photographed with an Electronic Scanner Microscope Jeol® JSV 6063 LV from the MATERIALS AND METHODS La Plata Museum. Helminths were deposited in Fourty-eight L. latrans (15 females, 23 males, the Helminthological Collection of the Museo de 10 sexually undifferentiated) were captured by La Plata (MLP-He). active search at night using the visual encounter survey technique (REV) (Crump & Scott 1994) RESULTS between 2011 and 2012 in the surroundings of La Plata city, Buenos Aires Province, Argentina Of the 48 frogs examined, 34 (71 %) were infected with authorization of the Dirección de Flora y with at least one parasite. Eight helminth taxa Fauna, M.A.A.BA (Exp n° 225500-11319/10). The (one acanthocephalan, two digeneans and five frogs were transported alive to the laboratory, nematodes) were found. then euthanized with an overdose of 20% benzocaine, and all organs were examined using Cosmocercidae (Raillet, 1916) Travassos, 1925 a Stemi 2000-C Zeiss stereoscope. Cosmocercoides latrans n. sp. (Figs. 1-2) Helminths were fixed in 5% formalin and Type host: Leptodactylus latrans (Steffen, 1815), preserved in 70% ethyl alcohol. Trematodes Criolla Frog (Leptodactylidae). were stained with a 1:6 dilution in 96% Site of infection: small intestine. ethanol of hydrochloric carmine, dehydrated, Type locality: Establecimiento Santa Ana cleared in xilol and mounted in Canada (35°02’23, 2’’S; 57°48’58, 2’’W), Buenos Aires, balsam. Acanthocephalans and nematodes Argentina. were cleared in Aman’s lactophenol and Type material: Holotype MLP-He 7626; Allotype examined as temporary mounts. The systematic MLP-He 7627; Paratypes, MLP-He 7628, 7629. determination of the helminths was carried Voucher specimens: MLP-He 76230. out following specific keys (Yamaguti 1961, Prevalence, mean intensity and intensity of 1963, Petrochenko 1971a, b, Anderson et al. 1974, infection: 4% (2 of 48), 79.5 ± 35.7 (29-130), 159. Gibson et al. 2002, Jones et al. 2005, Bray et al. Etymology: The specific name refers to the 2008) and drawings were made with the aid specific name of the host where the specimens of a drawing tube. Measurements are given in were found. micrometres (μm) unless otherwise stated, as the mean followed by the standard deviation, An Acad Bras Cienc (2020) 92(2) e20180499 2 | 14 REGINA DRAGHI, FABIANA B. DRAGO & LÍA I. LUNASCHI NEW SPECIES OF Cosmocercoides IN Leptodactylus latrans Figure 1. Scanning electron micrographs of Cosmocercoides latrans n. sp. a- Male anterior end. b- Male posterior end, ventrolateral view. c-Detail of the rosette papilla. Abbreviations: *= cephalic papilla; a= amphid; la= lateral alae; sp= somatic papilla; p= postcloacal papillae; rp= rosette papilla. Figure 2. Cosmocercoides latrans n. sp. a- Female, general view. b- Female anterior end, lateral view. c- Male posterior end, lateral view. d- Male, in face view. E- Male, posterior end, ventral view. Abbreviations: ap= adcloacal papilla; b= bulb; dl= dorsal lip; e= esophagus; ep= excretory pore; la= lateral alae; le= larvated egg; nr= nerve ring; p= pharynx; me= morulated egg; pcp= postcloacal caudal papillae; rp= rosette papilla; s= spicule; t=tail; up= unpaired papilla; v= vulva; vl= ventral lip. Scale bars: A= 600 μm; B= 241.5 μm; C =100 μm; D= 40 μm; E= 500 μm. An Acad Bras Cienc (2020) 92(2) e20180499 3 | 14 REGINA DRAGHI, FABIANA B. DRAGO & LÍA I. LUNASCHI NEW SPECIES OF Cosmocercoides IN Leptodactylus latrans Description bulb width 106.5 ± 15.36 (78.54-142.8). Nerve ring General morphology: Small, stout nematodes. 150.13 ± 32.65 (95.2-265.65) and excretory pore Sexual dimorphism evident, males half-length 331.13 ± 45.54 (217.35-406.14) from anterior end. of females. Lateral alae present in both males Vulva 2 ± 0.35 (1.4-2.75 mm from anterior end; 50 and females, extending from the anterior % of body length from anterior end). Tail long esophageal region to the tail. Cuticle transversely and sharp 408.4 ± 61.26 (252.28-483) in length. striated, somatic papillae present. Mouth with Eggs, oval, thin-shelled and in different stages three prominent lips, dorsal lip with two sessile of development; eggs near vulva containing fully papillae, each ventrolateral lip with one ventral developed larvae 84.67 ± 6.66 (73.78-98.5) long sessile papilla and one lateral amphid. Shallow and 48.67 ± 8.14 (33.08-73.78) wide. mouth cavity, short pharynx, cylindrical corpus, Aplectana hylambatis (Baylis, 1927) Travassos, short isthmus and valved bulb present. Excretory 1931 (Fig. 3a, b, c) pore anterior to esophageal bulb. Male (holotype and 14 paratypes, 6 Site of infection: Small and large intestine. specimens studied by SEM): Length 2.17 ± 0.37 Prevalence, mean intensity and intensity of (1.48-2.68 mm); width at midbody 0.26± 0.06 infection: 4.2% (2 of 48), 7.5 ± 4.6 (1-14), 23. (0.19-0.37mm). Esophagus: pharynx 34.71 ± 3.82 Voucher specimens: MLP-He 7631. (28.56-45.22) by 23.23 ± 6 (16.6-43), corpus 284.24 Other reported hosts and geographic range ± 26.6 (250-338), isthmus 43.6 ± 6.9 (35.7-59.5), in South America: Aplectana hylambatis is a bulb length 74.37 ± 6.17 (59.5-83.3), bulb width generalist species that parasitizes a wide range 81.78 ± 9.12 (66.64-102.34). Nerve ring 148.38 ± 17.87 of amphibian hosts. In the Neotropical region, (119-192.78) and excretory pore 290.35 ± 40.72 has been observed in different countries (Peru, (230.86-347.76) from anterior end. Tail 284.93 Paraguay, Uruguay, Brazil) and anuran families, ± 46.23 (178.5-364.14) long, tapering to sharp for example, Bufonidae, Ceratophrydae, Hylidae, point. Spicules robust,