M.M. Montes

Morphological and molecular identification of the fish-borne metacercaria of Ascocotyle (Phagicola) longa Ransom, 1920 in Mugil liza from Argentina

This is the first report of Ascocotyle (Phagicola) longa Ransom, 1920 (Digenea: Heterophyidae) in Argentina confirmed by morphological and molecular studies. The metacercaria was found encysted in myotomal musculature, heart and mesentery of the mullet Mugil liza (Pisces: Mugilidae) from Samborombon bay. We provide a morphological description of the metacercaria which we identified using species-specific primers for A. (Phagicola) longa and nucleotid sequence. This worldwide parasite has been reported as one of the causative agents of heterophyiosis, an emerging fish-borne disease of humans, contracted by the consumption of raw mullet. The discovery of A. (Phagicola) longa in Argentina represents a warning of the potentially great impact of this parasite on public health.

Integrative taxonomy of Peniculus, Metapeniculus, and Trifur (Siphonostomatoida: Pennellidae), copepod parasites of marine fishes from Chile: species delimitation analyses using DNA barcoding and morphological evidence

Pennellidae is a family of copepod parasites of widely distributed marine fishes. The pennellid species are usually morphologically differentiated by cephalothorax, neck, trunk, and abdomen shape. These characters, however, show high polymorphism and therefore using only this type of data, delimitation at species level of this genus is difficult. In this study, we explored the genetic distances calculated from sequences of a DNA barcoding marker (COI mt) (678 base pairs). We also explored the genetic distances of 25 Peniculus specimens associated within nine marine fish species, four Metapeniculus specimens associated within one marine fish species, and four Trifur specimens associated within one marine fish species. All specimens were collected in Antofagasta Bay, Chile and were calculated from sequences of a DNA barcoding marker (COI mt) (678 base pairs). The genetic distance among the Peniculus specimens was 0.95% from the different host species, the Metapeniculus specimens distance was 0.44% and the Trifur specimens was 2.25%. Genetic difference between Peniculus and Metapeniculus was 17.86% and Peniculus differ from T. tortuosus by 18.16%. We analysed the barcoding gene fragment using Bayesian Inference (BI) for phylogenetic reconstruction using three outgroups. Based on the phylogenetic analysis an ultrametric tree was built and a general mixed Yule-coalescent (bGMYC) model was conducted for species delimitation. Morphometrics analyses were made with Bayesian statistics. Mean and credibility limit (95%) for each parameter was calculated. Results show that based on morphology the individuals collected can be assigned to P. cf. fistula von Nordmann, 1832, Metapeniculus antofagastensis Castro-Romero & Baeza-Kuroki, 1985, and Trifur cf. tortuosus Wilson, 1917. High morphological polymorphism was observed for the lineage of Peniculus associated to several host species of marine fishes. Similar results were obtained for Trifur cf. tortuosus parasites on Chilean marine fishes.

Two new species of Syndesmis (Platyhelminthes, Rhabdocoela, Umagillidae) from the sea urchin Pseudechinus magellanicus (Echinodermata, Echinoidea) in the Southwestern Atlantic Ocean

In this paper, we describe two new species of Syndesmis living in Pseudechinus magellanicus in the Southwest Atlantic Ocean. The new species have a long stylet in the male reproductive system, which is different from that of the known species of the genus. Specimens of Syndesmis selknami n. sp. have a ∼220-μm-long stylet (∼1/3 of the body length, 0.69 mm). This ratio is unique because only four species (Syndesmis echinorum, Syndesmis rubida, Syndesmis inconspicua and Syndesmis echiniacuti) have similar stylet lengths but are larger in body sizes (3–5 mm). Specimens of Syndesmis aonikenki n. sp. have a ∼148-μm-long stylet (∼1/10 of the body length, 1.11 mm). Syndesmis pallida has a similar ratio but the uterus is located posteriorly, and the filament glands are very small and located in the posterior region of the body. These are the first flatworms reported parasitizing Pseudechinus magellanicus.

Screening for WSSV in crustacean from marine areas of Buenos Aires, Argentina

In total 374 specimens corresponding to four species of shrimp: Artemesia longinaris, Pleoticus muelleri, Peisos petrunkevitchii, Palaemon macrodactylus, and two species of crabs: Neohelice granulata and Cyrtograpsus angulatus were studied in the search of white spot syndrome virus (WSSV). The crustaceans were collected in the estuary of Bahia Blanca, the port of Mar del Plata and the Samborombon Bay, Argentina, between 2010 and 2014. A polymerase chain reaction (PCR) analysis in all of them has not detected any virus presence. These new results suggest that the discovery of infected shrimp in 2008-09 in the Bahia Blanca estuary may have been a one-time local event, promoted by special conditions of seawater temperature inside the estuary, coincident with the presence of a virus carrier or transporter. To determine if the virus was finally installed in the estuary of Bahia Blanca more screening are needed coming from a larger number of shrimp samples. These studies will be necessary mainly in A. longinaris (Penaeidae) since this family of shrimps is most susceptible to be affected by WSSV.

New data on the acanthocephalan Neoechinorhynchus villoldoi Vizcaíno, 1992 (Neoechinorhynchidae: Acanthocephala), based on specimens found in Austrolebias bellottii (Steindachner, 1881) (Rivulidae: Cyprinodontiformes) from Punta Indio, Argentina

Fil: Montes, Martin Miguel. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - La Plata. Centro de Estudios Parasitologicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitologicos y de Vectores; Argentina

Morphological identification and DNA barcoding of a new species of Parabrachiella (Siphonostomatoida: Lernaeopodidae) with aspects of their intraspecific variation

We present a detailed morphological description and a DNA barcoding of Parabrachiella platensis n. sp. collected from Mugil liza Valenciennes in Samborombon Bay (Buenos Aires, Argentina). This new species was compared with two Parabrachiella species parasitic on mugilids: Parabrachiella exilis (Shiino, 1956) and Parabrachiella mugilis (Kabata, Raibaut et Ben Hassine, 1971). Parabrachiella platensis n. sp. differs from those species in the shape of posterior processes, the anal slit with two pairs of bipartite papillae, the size of cephalothorax, the trunk, the maxilla, the microhabitat on the host, and the lack of caudal rami. On the host, the new species was in the nostrils (a new site for a species of the genus Parabrachiella) and in the fins base. Some minor morphological differences were observed in relation to the locations on the host. The molecular analysis conducted based on mtDNA-COI between specimens of the new species on the fins and nostrils showed a genetic similarity of 99.8%. This percentage supports that the specimens found in nostrils and fins base could represent a single species. New studies on P. platensis n. sp., including infection of the same fish with the two forms, could bring some new information. Anyway according to the genetic information provided and the minimal morphological differences spotted we conclude that the two forms are a single specie. The differences observed are possibly influenced by the place of the host where the two forms of copepods were found, nostrils and fins. The new species was also molecularly compared to other five species of Parabrachiella including P. exilis (parasitizing mugilid from Chile), Parabrachiella anisotremis, Parabrachiella auriculata, Parabrachiella merluccii, and P. hugu (the last two sequences were taken from the GenBank). The genetic distance of 9% among P. platensis n. sp. and P. exilis, which is the close morphological related species, allow to states that these two copepods on mugilids belong to different species and then validating the morphological differences found between them.

Riggia puyensis n. sp. (Isopoda: Cymothoidae) parasitizing Chaetostoma breve and Chaetostoma microps (Siluriformes: Loricariidae) from Ecuador

A new isopod was found parasitizing Chaetostoma breve and Chaetostoma microps from the Puyo and Bobonaza rivers. The parasite found belongs to the Cymothoidae family and could be located within the genus Riggia instead of Artystone by the presence of abdominal plates fused with the telson. The specimens found represent a new species, Riggia puyensis n. sp., and could be distinguished from Riggia cryptocularis by the presence of developed eyes. The main difference of the new specie from Riggia nana and Riggia brasiliensis is the size, bigger compared with the first and smaller compared with the last species. Riggia acuticaudata have the maxilliped with simple setae, the palp without spination, and maxillule with five spines (two terminal and three subterminal) instead in R. puyensis n. sp. the maxilliped have plumose setae, the palp have spination (with one apical spine, two setae on middle article and one in the basal article) and the maxillule have five spines: two terminal, two subterminal and other spine lower to the others. Riggia paranaensis have similar size, same number of segments in the antena, and similar maxilla to R. puyensis n. sp., but the antennule in the new specie have seven segments instead 6 in R. paranaensis, the antennule and antenna present spines not mentioned in R. paranaensis. Besides, the relative position of the mandible in R. puyensis n. sp. is different compared with R. paranaensis, the maxillule have the same number of spines but with different disposition, and the maxilliped have simple setae in R. paranaensis but those are plumose in the new specie.

An ecological and comparative analysis of parasites in juvenile Mugil liza (Pisces, Mugilidae) from two sites in Samborombón bay, Argentina

Mugil liza Valenciennes, 1836 is an economically important food fish and has been recommended for aquaculture in South America. A total of 278 fishes were collected in the spring and summer of 2009 and 2010. These fish were sorted into sample groups according to their size class. We used Bayesian statistics and 95% credible intervals for each parameter tested were calculated. Fish studied harbored a total of 15 different species of parasites. Diversity of parasite species found on Mugil liza was greatest at the S.R.C. collection site, but evidenced a lower species richness than at A.R. site. The 1st size fishes of both sites evidenced greater parasite diversity than either 2nd or 3rd size fish. Differences observed could be explained by the different use of habitat types at the two sites or differential susceptibility to infection by parasites. The dominance of D. fastigatainfluenced observed results of lower community diversity indexes. New works elucidating different parasite life cycles within juvenile and adults ofM. liza in Argentina, promise to be important for determining the risk of the parasitism by zoonotic metacercariae A. (P.) longa and use of this fish as food and an economic resource, and the possible use of mullet parasites in other promising fields as indicators of biodiversity, and/ or water contamination.