Urocleidoides spp. (Monogenea: Dactylogyridae) from the gills of Parodon nasus (Characiformes: Parodontidae) from a Brazilian stream with descriptions of two new species

Urocleidoides spp. are reported from the gills of 20 specimens of Parodon nasus (standard length 8.5–12 cm), from the Indiana stream, Tietê River, Upper Paraná River basin, municipality of Botucatu, São Paulo State, Brazil. Urocleoidoides tenuis and two new species were found. Urocleidoides indianensis n. sp. differs from its congeners mainly by the morphology of the vaginal sclerite that is robust, sickle-shaped, and forked at the distal end; and by the bulbous-shaped accessory piece of the male copulatory complex. Urocleidoides parodoni n. sp. resembles U. tenuis by presenting male copulatory organ with approximately 7 ½ counterclockwise rings, but differs by the morphology of the accessory piece (lobate with a small hook-like projection versus pincer-shaped), vaginal sclerite (thumb-like subterminal projection vs. presence of a distal hook), vaginal tube (conspicuously sclerotized vs. slightly sclerotized), shape of the ventral bar (bowed vs. wide V-shaped), ventral and dorsal anchors (robust base and short shaft vs. considerably less robust base and long shaft), and hooks (slender shank with a weakly sclerotized subunit at base vs. dilated shank). Sequences of the partial 28S rDNA gene of the dactylogyrids found in this study are provided. Phylogenetic analyses showed Urocledoides spp. from Parodontidae clustering together with strong support values. This study increases the number of valid Urocleidoides species to 39, and the number of species described from parodontid hosts to four.

Three new species of Urocleidoides (Monogenoidea: Dactylogyridae) parasitizing characiforms (Actinopterygii: Characiformes) in Tocantins River, states of Tocantins and Maranhão, and new record for U. triangulus in Guandu River, state of Rio de Janeiro, Brazil

Three new species of Urocleidoides Mizelle & Price, 1964 are described from the gills of characiform fishes in the Tocantins River and its tributaries. Urocleidoides boulengerellae sp. nov. is described from Boulengerella cuvieri (Spix & Agassiz, 1829) and differs from all its congeners by the dorsal bar with a long posteromedial projection; male copulatory organ with 2–3 counterclockwise rings and a base with a flange; an accessory piece comprising a robust Y-shaped unit and a sheath-like unit; and a highly sclerotized vaginal canal. Urocleidoides paratriangulus sp. nov., described from Psectrogaster amazonica Eigenmann & Eigenmann, 1889, Cyphocharax gouldingi Vari, 1992, Caenotropus labyrinthicus (Kner, 1858) and Mylesinus paucisquamatus Jégu & Santos, 1988, is most similar to Urocleidoides triangulus (Suriano, 1981) Rossin & Timi, 2016 based on the shape of the anchors and bars but differs from U. triangulus in the morphology of the projection of the dorsal bar, the number of rings of male copulatory organ, and by the smaller size of members of hook pairs 1 and 5 compared with those of the remaining pairs. Urocleidoides tocantinensis sp. nov. is easily distinguished from all other species of the genus by the morphology of the vagina, which present a vaginal vestibule with a membranous cap. Urocleidoides triangulus is reported from its type host in the Guandu River, state of Rio de Janeiro. The present study increases the number of Urocleidoides species to 37 recognized species that fit all the generic characters.

Two new species of monogenoidean parasites (Platyhelminthes: Neodermata) of ornamental fish of Loricariidae (Siluriformes) from the Xingu River, Brazilian Amazon

Two new monogenoidean species of Unilatus Mizelle & Kritsky, 1967 found in the gills of loricariids in the Lower Xingu-Iriri rivers are described: Unilatus humboldtii sp. nov. from Baryancistrus niveatus (Castelnau, 1855), Panaque armbrusteri Lujan, Hidalgo & Stewart, 2010, Pseudacanthicus sp. (type-host), and Scobinancistrus aureatus Burgess, 1994; and Unilatus luciarappae sp. nov. from P. armbrusteri. Unilatus humboldtii sp. nov. is distinguished from other congeneric species due to its anterior anchor with well-developed superficial root with depressed or truncated distal portion, and inconspicuous or reduced deep root; anterior bar with posteromedial projection; hooks of pair 1 with dilated shaft comprising 2/3 of the hook length; spiraled male copulatory organ with approximately 16–18 counterclockwise loops. Unilatus luciarappae sp. nov. is characterized by having anterior anchor with well-developed superficial root and reduced deep root, slightly curved shaft, elongated, slightly curved, and tapered point; spiraled MCO with approximately 18–19 counterclockwise loops, with median distal bulbous portion and remaining portion tapered and elongated, comprising 1/4 of the body length; and accessory piece comprising approximately 2/3 of the MCO length. More than fifty years after the description of the type species of Unilatus from an artificial environment (U.S. aquaria), this study represents the first formal record and description of Unilatus species from hosts collected in natural habitats in the Xingu River. Considering the impact of the Belo Monte dam on the formerly pristine conditions of the study region and the importance of loricariids for the ornamental fish trade, we recommend monitoring monogenoidean diversity, parasite-host interaction, as well as the dispersion patterns and pathogenicity of these parasites.

Nematodes from the Tasmanian devil (Sarcophilus harrisii (Boitard)), with the description of Sarcophiloxyuris longus n. gen. and n. sp. (Oxyuridae)

The Tasmanian devil (Sarcophilus harrisii (Boitard)) is an endangered carnivorous marsupial, limited to the islands of Tasmania in southern Australia. The parasites of the Tasmanian devil are understudied. This study aimed to increase the knowledge of the nematode fauna of Tasmanian devils. Ten Tasmanian devils were examined for parasites from northern and southern Tasmania. Nematodes that were collected were morphologically characterized as two separate species. Molecular sequencing was undertaken to verify the identity of these species. A new genus and species of oxyurid nematode was collected from a single Tasmanian devil from the northern part of Tasmania. The nematode is differentiated from oxyurids described from other Australian amphibians, reptiles and marsupials by the characters of the male posterior end – that is, in having three pairs of caudal papillae, two pairs peri-cloacal, one large pair post-cloacal, a long tapering tail, a stout spicule and a gubernaculum and accessory piece, as well as its much larger overall size. Molecular sequencing was unsuccessful. The remaining nematodes collected from the Tasmanian devil in this study were all identified as Baylisascaris tasmaniensis Sprent, 1970, through morphology and molecular sequencing. This paper presents the first description of a new genus and species of oxyurid nematode from the Tasmanian devil, Sarcophiloxyuris longus n. gen., n. sp. The need to undertake more sampling of the parasites of endangered hosts, such as the Tasmanian devil, to assist with a better understanding of their conservation management, is discussed.

Description of a new species, Actus hagiangensis (Mononchida, Mylonchulidae) from Ha Giang province, Vietnam

Actus hagiangensis sp. nov. is described and illustrated from Vietnam. Females of the new species are characterized by medium body size (L = 1.1–1.4 mm), barrel shaped buccal cavity of medium size (26–31 x 13–15 µm) with dorsal tooth apex located 75–81% of buccal cavity length from base and two longitudinal subventral rows, each with four rasp-like denticles; reproductive system didelphic-amphidelphic, vagina short with distinct par refringens vaginae, sclerotized pieces globular in optical section; tail elongate-conoid, slightly ventrally arcuate, with three caudal glands and prominent spinneret. Male with spicules 46 µm in length, and slender, slightly curved gubernaculum, 12 µm long, without accessory piece. This is the first report of a male specimen of the genus Actus. The new species is close to A. salvadoricus but differs by the larger buccal cavity, more anterior position of the dorsal tooth apex and more rounded vaginal sclerotized pieces.

Dactylogyridae (Monogenoidea, Polyonchoinea) from the gills of Auchenipterus nuchalis (Siluriformes, Auchenipteridae) from the Tocantins River, Brazil

Two species of Cosmetocleithrum Kritsky, Thatcher & Boeger, 1986 (both new) and two species of Demidospermus Suriano, 1983 (one new) are reported from the gills of the catfish Auchenipterus nuchalis, popularly known as “mapará”, from the Tocantins River and tributaries, North Region of Brazil. Cosmetocleithrum berecae n. sp. differs from all other species presently known in the genus by the morphology of the anchors presenting an elongate shaft and short recurved point, a coiled male copulatory organ (MCO) with three rings, and an elongate slender accessory piece with a bifurcated distal end. Cosmetocleithrum nunani n. sp. differs from its congeners by the combination of the following features: (1) Ventral and dorsal anchors with moderately long curved shaft and short point; (2) Hooks with poorly developed thumb; (3) Hook pairs 5 and 6 similar to each other, but morphologically distinct from remaining hook pairs; and (4) MCO coiled, with approximately 1.5 rings. Demidospermus tocantinensis n. sp. is easily distinguished from other species of the genus by presenting an inverted-G-shaped MCO with a median knee-like expansion. Demidospermus osteomystax Tavernari, Takemoto, Lacerda & Pavanelli, 2010 is redescribed based on paratypes and specimens from the gills of A. nuchalis from the Tocantins River, a new host and locality records for this species. The monotypic Paracosmetocleithrum Acosta, Scholz, Blasco-Costa, Alves & Silva, 2017, the only other Neotropical genus reported in siluriforms besides Cosmetocleithrum with species presenting two ribbon-like projections on the posterior margin of the dorsal bar, is considered a junior subjective synonym of Cosmetocleithrum.

New species of Urocleidoides (Monogenoidea: Dactylogyridae) from the gills of two species of Anostomidae from the Brazilian Amazon

Three species (2 new) of Urocleidoides are described and/or reported from the gills of Schizodon fasciatus and Laemolyta proxima (Anostomidae) from the Jari River in the eastern Brazilian Amazon. Urocleidoides jariensis n. sp. presents a sclerotized, tubular, spiral male copulatory organ (MCO) with one counterclockwise coil, a circular sclerotized tandem brim associated with the base of the MCO; a heavily sclerotized, funnel-shaped vaginal vestibule; and a broadly V-shaped ventral bar with anteromedial constriction and enlarged ends. Urocleidoides ramentacuminatus n. sp. has a sclerotized, tubular, spiral MCO with one counterclockwise coil; an accessory piece with a hook-shaped distal portion; and a dorsal anchor with a short, straight shaft; anchor point with ornamentation as sclerotized shredded filaments. Urocleidoides paradoxus is reported for the first time parasitizing S. fasciatus.

Monogenoids (Polyonchoinea, Dactylogyridae) from Hydrolycus armatus (Characiformes, Cynodontidae) with the description of a new species of Rhinoxenus and the proposal of a new genus from the Xingu River, Pará, Brazil

One new species of Rhinoxenus Kritsky, Boeger & Thatcher, 1988 from the nasal cavities and four new species of Mymarothecioides n. gen. from the gills are described in Hydrolycus armatus (Jardine & Schomburgk). They were collected in the Xingu River, Pará, Brazil. Rhinoxenus cachorra n. sp. is characterized by having a ventral anchor with inconspicuous roots, and point with fish-hook-like termination; copulatory complex comprising a spiraled male copulatory organ (MCO) with two counterclockwise coils, and an accessory piece with an expanded, bifurcated distal portion. Mymarothecioides n. gen. is proposed and characterized for species without eyes, with or without accessory chromatic granules; copulatory complex comprising articulated MCO, accessory piece; MCO a broad arcuate tube; an accessory piece with a hooked termination in the distal portion; a dextro or midventral non-sclerotized vagina; an anteromedial projection on the ventral bar. Mymarothecium whittingtoni Kritsky, Boeger & Jégu, 1996 is transferred to Mymarothecioides n. gen. as Mymarothecioides whittingtoni (Kritsky, Boeger & Jégu, 1996) n. comb.

Dactylogyrids (Platyhelminthes: Monogenoidea) Infecting the Gill Lamellae of Flatheads (Scorpaeniformes: Platycephalidae), with Proposal of Platycephalotrema n. gen. and Descriptions of New Species from Australia and Japan

Platycephalotrema n. gen. (Dactylogyridae) is proposed for four new species and 5 previously described species parasitizing the gills of flatheads (Scorpaeniformes: Platycephalidae) as follows: Platycephalotrema ogawai n. sp. (type species) from Platycephalus sp. 1 (type host) and Platycephalus sp. 2, both of Nakabo & Kai (2013) (locally known as “Yoshino-gochi” and “Ma-gochi,” respectively) (Japan); Platycephalotrema austrinum n. sp. from Platycephalus endrachtensis Quoy & Gaimard (type host) and Platycephalus sp. (Australia); Platycephalotrema bassensis (Hughes, 1928) n. comb. from Platycephalus bassensis Cuvier (Australia); Platycephalotrema koppa n. sp. from Platycephalus fuscus Cuvier (Australia); Platycephalotrema macassarensis (Yamaguti, 1963) n. comb. from Platycephalus indicus (Linnaeus) (China, Macassar); Platycephalotrema mastix n. sp. from P. fuscus and P. endrachtensis (Australia); Platycephalotrema platycephali (Yin & Sproston, 1948) n. comb. from P. indicus (China) and P. fuscus (Australia); Platycephalotrema sinensis (Yamaguti, 1963) n. comb. from Cociella punctata (Cuvier) (China); Platycephalotrema thysanophrydis (Yamaguti, 1937) n. comb. from Inegocia japonica (Cuvier), Inegocia ochiaii Imamura, and Cociella crocodilus (Cuvier) (Japan, China). Other species requiring further study but potentially members of Platycephalotrema include Ancyrocephalus vesiculosus Murray, 1931, Haliotrema indicum Tripathi, 1957, Haliotrema swatowensis Yao, Wang, Xia, & Chen, 1998, and Haliotrema pteroisi Paperna, 1972. The primary features differentiating Platycephalotrema include species having: (1) tandem gonads (testis postgermarial); (2) two prostatic reservoirs, each emptying independently into the base of the male copulatory organ; (3) a dextral vaginal pore and large vaginal vestibule; (4) dorsal and ventral pairs of morphologically similar anchors; (5) a ventral bar with spatulate ends; (6) a dorsal bar with bifurcated ends, and (7) absence of an accessory piece. The new species are described, and P. thysanophrydis is redescribed based on newly collected and museum specimens.

New species of Synodontella (Monogenea, Ancyrocephalidae) gill parasites of two Synodontis spp. (Pisces, Mochokidae) from the Boumba River (Congo Basin, East Cameroon)

Three new species of Synodontella Dossou & Euzet, 1993 are described from two species of Synodontis (Mochokidae) collected from the middle course of the Boumba River (East Cameroon): Synodontella angustupenis n. sp. from Synodontis nummifer, Synodontella longipenis n. sp. and Synodontella simplex n. sp. from Synodontis decorus. These new species are different from the other Synodontella species already described due to their horseshoe-shaped dorsal transverse bars. Synodontella angustupenis differs from S. longipenis and S. simplex by the morphology of its penis, a thin tube, and its accessory piece, bifid at its extremity. Synodontella longipenis differs from the other two species by the morphology and the size of its male copulatory organ, which is very long. Synodontella simplex differs from S. angustupenis and S. longipenis by the shape of its penis, which is simple, and of its accessory piece, with a developed heel. The difference between the dorsal transverse bars of Synodontella species from the Sanaga River in Cameroon (and other localities in Africa), slightly curved, and those from the Boumba River, horseshoe-shaped, makes it possible to separate Synodontella species into two different subgroups. This difference can be explained by a long isolation period of the hosts, living in different river basins, followed by the divergence of the parasite populations (vicariant speciation).