Systematic assessment of nymphs of Diesingiinae (Pentastomida: Sebekidae) parasitizing Palloceros harpagos (Cyprinodontiformes: Poeciliidae) from Parque Nacional Iguazú, Argentina: filling gaps in an incomplete phylogenetic framework.

During a search for parasites in fishes from Iguazu River, Argentina, a nymph of pentastomid was found encysted on mesenteries of Phalloceros harpagos. The 28S rDNA and COI mt-DNA were used to compare with the sequences deposited in the GenBank. Pentastomid nymphs belong to the subfamily Diesingiinae (Sebekidae) for having chloride cell pores distributed in a single row per annulus; also, the hooks and rows of spines of our material differ to other genera. Present specimens are most likely Diesingia sp., having 63-74 annuli, a U shaped oral cadre with fibers closing anteriorly and a peg like extension of the oral cadre. The 28S rDNA analysis places our samples into a sister group of Alofia sp., but the COI mt-DNA situate them on the base of the clade. In conclusion, our pentastomid positively belongs to Diesingia sp., however, indisputable assignation requires a reliable description of the nymph, or the availability of sequences linking nymphs and adults, which even could provide evidence of a new hitherto undescribed genus. Aditionally, the systematic position of Sebekia oxycephala previously described by P. harpagos is discussed on the basis of our results, allowing us to suggest a re-assignation of such specimens to the genus Diesingia.

Phylogenetic position of the South American freshwater Rhipidocotyle santaensis (Digenea:Bucephalidae) based on partial 28S rDNA.

The family Bucephalidae is comprised of nine subfamilies, the most important being Bucephalinae with eight genera. Among these, the genus Rhipidocotyle has been found in marine and freshwater environments all over the world. Previous studies of Rhipidocotyle santanaensis have dealt with its morphology or host's ecology. Here, we provide a phylogenetic analysis based on two 28S rDNA sequences from R. santanaensis parasitizing the freshwater fish Acestrorhynchus pantaneiro from the Ibera Lagoon (Corrientes Province, Argentina). The 28S rDNA tree showed that it clustered together with Rhipidocotyle species from Middle and North America, suggesting a common history. Bucephalinae appears to have undergone four evolutionary processes: first, the diversification within the same host family; second, more than one successful infection of the same host family in different geographic regions; third, "jumping" between host families; and, finally, successful invasion of the freshwater environment (occurring in at least four different events in the subfamily). We hypothesize that R. santanaensis entered the freshwater environment by a "jumping" event from some unknown marine host family when a seawater ingression took place in South America during the Late Quaternary. This is the first sequenced Bucephalinae species from South America. Further sequencing will help shed light on the evolutionary relationships between South American members of this group from marine and, especially, freshwater environments.

Maxiclavella and Praeclavella (Siphonostomatoida: Lernaeopodidae) new genera confirmed by molecular and morphological evidence.

The new genus Maxiclavella is proposed to accommodate Clavella simplex Castro Romero and Baeza Kuroki, 1985, which differs from Clavella species, including long and narrow cephalothorax, small bulla, and simple armature of the antenna and antennule. Praeclavella nasalis, new genus and species, was found parasitizing the olfactory sacs of Isacia conceptionis. Praeclavella nasalis could be differentiated from other Clavella species by a biramous antenna with an exopod shorter than the endopod, the base of the cephalothorax with a large lobular and suborbicular projection on each side, a suborbicular bulla, mandibles without secondary teeth, and a suboval male body type. Males of both genera fit well in the Clavella-clade male type, although they differ from each other in many aspects, mainly in the position of the buccal area, which is oriented ventrally in Maxiclavella and distally in Praeclavella nasalis, and in a genital process, which is present in the latter and absent in the former. Genetic distances of mtDNA COI and 28S rDNA supported the validity of the two new genera parasitizing the same host, I. conceptionis. Also Clavella-branch (Clavellinae Wilson), a key based genera on female specimens is presented.

Molecular phylogenetic relationship between Philometroides tahieli (Nematoda, Philometridae) and other philometrids from South America.

In South America, the family Philometridae is represented by several genera and species. In particular, Philometra and Philometroides are the most speciose genera. In Argentina, only Philometroides tahieli has been reported so far. The main objective of this study was to analyze the phylogenetic relationship between Ps. tahieli and other South American philometrids using molecular data. The molecular analysis was performed using a female specimen of Ps. tahieli found on the opercular muscle of a juvenile Micropogonias furnieri from brackish waters in Argentina. Phylogenetic relationships were studied based on partial sequences of the 18S rDNA and 28S rDNA genes. In the 18S rDNA tree, Ps. tahieli was mainly grouped with other Philometroides from freshwater hosts from China, sharing the site of infection (head tissues or muscles). In the 28S rDNA tree, obtained with fewer sequences, Ps. tahieli is related species from subcutaneous tissues of head. This study contributes with information on philometrids and confirms the presence of different lineages among South American species, with Ps. tahieli representing a new one. Further studies on South American species using more molecular markers and new morphological characters will improve our knowledge of philometrid biodiversity and phylogeny.

Molecular evidence supports the validity of three Parabrachiella species infecting mugilids.

The parasitic copepod genus Parabrachiella is composed of 70 species, 14 of which are found in South America. The finding of new specimens of Parabrachiella mugilis from Turkey allowed us to compare the nucleotide sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene of this species with those of the South American Parabrachiella exilis and Parabrachiella platensis; all these species are parasites of mugilids. In addition, specimens of Parabrachiella fasciata, Parabrachiella oralis and Parabrachiella dispar from Chile, and Parabrachiella chevreuxi from Argentina were included in the comparison. Our results confirmed that the three Parabrachiella species parasitizing mugilids, which had been identified by morphology, are valid entities. However, P. exilis was recently synonymized with P. mugilis. The latter species showed a great genetic distance from P. exilis (16%) and was closer to Parabrachiella fasciata (13%) and to species with long posterior processes. Parabrachiella exilis and P. platensis (parasite on Mugil cephalus and Mugil liza, respectively) had a low genetic distance (9%) and Parabrachiella kabatai (parasite of Isacia conceptionis) had a low genetic distance (12-13%) from P. fasciata, P. platensis and P. exilis. In addition, the three parasitic copepods from South America have short and round posterior processes compared to other species, which have long posterior processes. Most species with long posterior processes are clustered together in a Pacific Ocean clade (P. hugu from the North Pacific Ocean), with the exception of P. chevreuxi, which has been found in the South Atlantic Ocean. This study adds seven new sequences, making a total of nine sequenced South American species of Parabrachiella.

Flight muscles in falcons (Falconiformes, Falconinae): A quantitative approach.

The family Falconidae has contrasting behaviors on its flight within the subfamilies. Falcons are primarily aerial predators requiring accuracy, high speed, and controlled movements during flight. Caracaras are generalists that seek food while walking and their flight is characterized as slow and erratic. We aimed to explore the muscle mass of the primary wing muscles in several species of Falconinae and to identify possible differences related to the role that these muscles perform during flight. We studied 34 wing muscles in 11 specimens of five species of falcons. The percentage of each muscle with respect to body mass was calculated as well as the total wing muscle mass. The search for differences between muscles of falcons and caracaras was analyzed using Bayesian statistical inference. Published data from Polyborinae were used for comparison. Five muscles were significantly different between both subfamilies mm. latissimus dorsi pars caudalis, biceps brachii, extensor carpi radialis, flexor digitorum superficialis, and extensor digitorum communis. The first two muscles were larger in Polyborinae, which could be useful to achieve more strength and stabilization. In falcons the last three muscles listed were larger, which might be associated with their fast and acrobatic flight. Variations in certain muscles generate, in turn, differences in function, which is reflected in their type of flight and its use. These findings reinforce the modular character of the locomotor system of birds whereby the regions involved in locomotion can have morphological peculiarities according to their lifestyle.

New insights on Pomphorhynchus sphaericus Gil de Pertierra, Spatz et Doma, 1996 (Acanthocephala: Pomphorhynchidae).

The finding of Pomphorhynchus sphaericus in new localities from La Plata River allowed the reevaluation of the species using a taxonomic integrative approach. The newly found specimens in Pimelodus maculatus from Samborombon Bay differ from P. sphaericus by the roots of hooks 1-6 which not form a wide sheet split into 2 apophysis, the slender, separated and equatorial testicles, the position of the cement glands, the shape of the proboscis, the shape and length of lemnisci, and the eggs size. Despite the notorious observed morphological differences, the COI mtDNA analysis confirmed that Pomphorhynchus individuals are the same conspecific, and showed that there is a high phenotypical plasticity in this species. Pomphorhynchus sphaericus is the first South American species analyzed to a DNA level (COI mtDNA, ITS, and 18S rDNA genes). The molecular analysis relates P. sphaericus to P. bulbocolli and P. purhepechus.

Molecular data reveal hidden diversity of the genus Clinostomum (Digenea, Clinostomidae) in Argentina, with the description of a new species from Ardea cocoi (Ardeidae).

The genus Clinostomum has been recently a subject of a large number of molecular phylogenetic studies that have uncovered a larger species diversity than we thought. In Argentina, only two nominal species have been reported, namely C. detruncatum and C. marginatum. Three putative species represented by metacercariae were recently molecularly diagnosed, and there are at least two additional metacercarial morphotypes diagnosed on morphological grounds. Here, we molecularly characterized specimens of Clinostomum sampled from freshwater fishes and fish-eating birds from Argentina through mtDNA cytochrome c oxidase subunit I (COI). Unexpectedly, the phylogenetic analysis uncovered three new additional genetic lineages, two of them corresponding to metacercarial stages and another matching COI sequences of C. heluans Braun, 1899, being considered conspecific, whereas the others still require formal description. Additionally, we add a new host species for a lineage molecularly diagnosed in a previous study. The adult specimens recovered from A. cocoi in Buenos Aires Province represented a new species clearly distinguished from the two species previously reported in Argentina. Clinostomum detruncatum is distinguished from the new species by possessing a characteristic tenoidean uterus, and testes located more posteriorly. Clinostomum marginatum is morphologically similar but differs from the new species in having rounded ovary, posterior testis lobated, and lateral cirrus-sac and displacing the anterior testis, and vitelline follicles not extending beyond the caeca end. Our study raises the number of Clinostomum species in Argentina up to 10. We describe the new species herein.