Morphological and molecular confirmation of Myxobolus cerebralis myxospores infecting wild­caught and cultured trout in North Carolina (SE USA).

We used microscopy and molecular biology to provide the first documentation of infections of Myxobolus cerebralis (Myxozoa: Myxobolidae), the etiological agent of whirling disease, in trout (Salmonidae) from North Carolina (USA) river basins. A total of 1085 rainbow trout Oncorhynchus mykiss, 696 brown trout Salmo trutta, and 319 brook trout Salvelinus fontinalis from 43 localities across 9 river basins were screened. Myxospores were observed microscopically in pepsin-trypsin digested heads of rainbow and brown trout from the Watauga River Basin. Those infections were confirmed using the prescribed nested polymerase chain reaction (PCR; 18S rDNA), which also detected infections in rainbow, brown, and brook trout from the French Broad River Basin and the Yadkin Pee-Dee River Basin. Myxospores were 9.0-10.0 µm (mean ± SD = 9.6 ± 0.4; N = 119) long, 8.0-10.0 µm (8.8 ± 0.6; 104) wide, and 6.0-7.5 µm (6.9 ± 0.5; 15) thick and had polar capsules 4.0-6.0 µm (5.0 ± 0.5; 104) long, 2.5-3.5 µm (3.1 ± 0.3; 104) wide, and with 5 or 6 polar filament coils. Myxospores from these hosts and rivers were morphologically indistinguishable and molecularly identical, indicating conspecificity, and the resulting 18S rDNA and ITS-1 sequences derived from these myxospores were 99.5-100% and 99.3-99.8% similar, respectively, to published GenBank sequences ascribed to M. cerebralis. This report comprises the first taxonomic circumscription and molecular confirmation of M. cerebralis in the southeastern USA south of Virginia.

Is Marine Dispersion of the Lethargic Crab Disease Possible? Assessing the Tolerance of Exophiala cancerae to a Broad Combination of Salinities, Temperatures, and Exposure Times.

Since 1997, an emergent fungal disease named lethargic crab disease (LCD) has decimated stocks of the edible mangrove land crab Ucides cordatus (Linnaeus, 1763) (Brachyura: Ocypodidae) along the Brazilian coast, threatening the mangrove ecosystem and causing socioeconomic impacts. Evidence from a variety of sources suggests that the black yeast Exophiala cancerae (Herpotrichiellaceae, Chaetothyriales) has been responsible for such epizootic events. Based on the spatiotemporal patterns of the LCD outbreaks, the well-established surface ocean currents, and the range of ecological traits of Exophiala spp., a marine dispersal hypothesis may be proposed. Using in vitro experiments, we tested the survival and growth of E. cancerae CBS 120420 in a broad combination of salinities, temperatures, and exposure times. While variation in salinity did not significantly affect the growth of colony-forming units (CFUs) (P > 0.05), long exposure times visibly influenced an increase in CFUs growth (P < 0.05). However, higher temperature (30 °C) caused a reduction of about 1.2-fold in CFUs growth (P < 0.05). This result suggests that sea surface temperatures either above or below the optimum growth range of E. cancerae could play a key role in the apparent north-south limits in the geographical distribution of LCD outbreaks. In light of our results, we conclude that a fundamental step toward the understanding of LCD epidemiological dynamics should comprise a systematic screening of E. cancerae in estuarine and coastal waters.

Two new species of Elopicola (Digenea: Aporocotylidae) from Hawaiian ladyfish, Elops hawaiensis (Eastern Sea) and Atlantic tarpon, Megalops atlanticus (Gulf of Mexico) with a comment on monophyly of elopomorph blood flukes.

Elopicola bristowi sp. n. infects the blood vascular system of Hawaiian ladyfish, Elops hawaiensis, in the Eastern Sea. It differs from the only nominal congener Elopicola nolancribbi by the combination of having rows of ventrolateral tegumental spines, a proportionally long oesophagus, anterior caeca, vasa efferentia coalescing ventral to the posterodextral margin of the testis, a post-testicular metraterm, a dextral common genital pore lateral to the oötype, and genitalia that are enantiomorphic relative to those of E. nolancribbi. Elopicola franksi sp. n. infects the heart and blood vascular system of Atlantic tarpon, Megalops atlanticus, in the Gulf of Mexico. It differs from its congeners by the combination of lacking ventrolateral tegumental spines and having an elongate body (6× longer than wide), a proportionally long oesophagus, a compact testis at level of the distal ends of the posterior caeca, and a post-testicular common genital pore at level of the oötype. Phylogenetic analyses based on the small subunit ribosomal DNA (18S), large subunit ribosomal DNA (28S), and internal transcribed spacer 2 (ITS2) genes revealed considerable genetic differences between these taxa. The 18S+28S tree showed a monophyletic Elopicola sister to all aporocotylids infecting fishes of Euteleosteomorpha. The ITS2 tree showed Paracardicoloides yamagutii as the sister taxon to Elopicola spp.

A new species of Spirorchis MacCallum, 1918 (Digenea: Schistosomatoidea) and Spirorchis cf. scripta from chicken turtle, Deirochelys reticularia (Emydidae), with an emendation and molecular phylogeny of Spirorchis.

Chicken turtles, Deirochelys reticularia (Latreille in Sonnini et Latreille) (Testudines: Emydidae) from Alabama, USA were infected by Spirorchis collinsi Roberts et Bullard sp. n. and Spirorchis cf. scripta. The new species is most easily differentiated from its congeners by the combination of having caeca that extend far beyond the genitalia, intercaecal genitalia positioned in the middle portion of the body, a testicular column that nearly abuts the caecal bifurcation, a cirrus sac positioned between the testes and ovary, a massive Mehlis' gland, an elongate, longitudinal metraterm that extends anteriad beyond the level of the ovary, a pre-ovarian genital pore, and a prominent, intercaecal Manter's organ. The specimens of S. cf. scripta differed from the holotype and published descriptions of Spirorchis scripta Stunkard, 1923 by several subtle morphological features, perhaps comprising intraspecific variation, but collectively warranted a detailed description herein. Based on examinations of the aforementioned specimens plus the holotype, paratypes and vouchers of morphologically-similar congeners, Spirorchis MacCallum, 1918 is emended to include the presence of oral sucker spines, a pharynx, lateral oesophageal diverticula ('plicate organ') and a median oesophageal diverticulum ('oeseophageal pouch'). Phylogenetic analysis of the nuclear large subunit rDNA (28S) recovered S. collinsi sister to Spirorchis picta Stunkard, 1923, > 99% similarity between S. cf. scripta and S. scripta, and a monophyletic Spirorchis MacCallum, 1918. No blood fluke infection has been reported previously from these drainages, Alabama, or this turtle species. This is the first new species of Spirorchis to be described from North America in 26 years.

Blood flukes of Asiatic softshell turtles: revision of Coeuritrema Mehra, 1933 (Digenea: Schistosomatoidea) and a new species infecting Chinese softshell turtles, Pelodiscus sinensis (Trionychidae), from Vietnam.

Coeuritrema Mehra, 1933, previously regarded as a junior subjective synonym of Hapalorhynchus Stunkard, 1922, herein is revised to include Coeuritrema lyssimus Mehra, 1933 (type species), Coeuritrema rugatus (Brooks et Sullivan, 1981) comb. n., and Coeuritrema platti Roberts et Bullard sp. n. These genera are morphologically similar by having a ventral sucker, non-fused caeca, two testes, a pre-testicular cirrus sac, an intertesticular ovary, and a common genital pore that opens dorsally and in the sinistral half of the body. Phylogenetic analysis of the D1-D3 domains of the nuclear large subunit ribosomal DNA (28S) suggested that Coeuritrema and Hapalorhynchus share a recent common ancestor. Coeuritrema is morphologically most easily differentiated from Hapalorhynchus by having ventrolateral tegumental papillae and a definitive metraterm that is approximately 3-7× longer than the uterus. Coeuritrema comprises species that reportedly infect Asiatic softshell turtles (Testudines: Trionychidae) only, whereas Hapalorhynchus (as currently defined) comprises blood flukes that reportedly infect those hosts plus North American musk turtles (Sternotherus Bell in Gray) and mud turtles (Kinosternon Spix), both Kinosternidae, North American snapping turtles (Chelydridae), Asiatic hard-shelled turtles (Geoemydidae) and African pleurodirans (Pelomedusidae). Coeuritrema platti sp. n. infects the blood of Chinese softshell turtles, Pelodiscus sinensis (Wiegmann), cultured in the Da Rang River Basin (Phu Yen Province, Vietnam). It differs from C. lyssimus by having a narrow hindbody (< 1.6× forebody width), ventrolateral tegumental papillae restricted to the hindbody, a short cirrus sac (< 10% of corresponding body length), a transverse ovary buttressing the caeca, a short, wholly pre-ovarian metraterm (~ 10% of corresponding body length), and a submarginal genital pore. It differs from C. rugatus by having small ventrolateral tegumental papillae, testes without deep lobes, and a Laurer's canal pore that opens posterior to the vitelline reservoir and dorsal to the oviducal seminal receptacle. The new species is only the second turtle blood fluke reported from Vietnam.

New Genus of Blood Fluke (Digenea: Schistosomatoidea) from Malaysian Freshwater Turtles (Geoemydidae) and its Phylogenetic Position Within Schistosomatoidea.

: Baracktrema obamai n. gen., n. sp. infects the lung of geoemydid turtles (black marsh turtle, Siebenrockiella crassicollis [type host] and southeast Asian box turtle, Cuora amboinensis ) in the Malaysian states of Perak, Perlis, and Selangor. Baracktrema and Unicaecum Stunkard, 1925 are the only accepted turtle blood fluke genera having the combination of a single cecum, single testis, oviducal seminal receptacle, and uterine pouch. Baracktrema differs from Unicaecum by having a thread-like body approximately 30-50× longer than wide and post-cecal terminal genitalia. Unicaecum has a body approximately 8-12× longer than wide and terminal genitalia that are anterior to the distal end of the cecum. The new genus further differs from all other accepted turtle blood fluke genera by having a cecum that is highly convoluted for its entire length, a spindle-shaped ovary between the cirrus sac and testis, a uterine pouch that loops around the primary vitelline collecting duct, a Laurer's canal, and a dorsal common genital pore. Phylogenetic analysis of the D1-D3 domains of the nuclear large subunit ribosomal DNA (28S) revealed, with high nodal support and as predicted by morphology, that Baracktrema and Unicaecum share a recent common ancestor and form a clade sister to the freshwater turtle blood flukes of Spirorchis, paraphyletic Spirhapalum, and Vasotrema and that, collectively, these flukes were sister to all other tetrapod blood flukes (Hapalorhynchus + Griphobilharzia plus the marine turtle blood flukes and schistosomes). Pending a forthcoming emended morphological diagnosis of the family, the clade including Spirorchis spp., paraphyletic Spirhapalum, Vasotrema, Baracktrema, and Unicaecum is a likely placeholder for "Spirorchiidae Stunkard, 1921 " (type genus Spirorchis MacCallum, 1918 ; type species Spirorchis innominatus Ward, 1921 ). The present study comprises the 17th blood fluke known to infect geoemydid turtles and the first proposal of a new genus of turtle blood fluke in 21 yr.

Two New Genera of Fish Blood Flukes (Digenea: Aporocotylidae) from Catfishes in the Peruvian Amazon.

Cladocaecum tomasscholzi n. gen., n. sp. infects the heart (lumen of ventricle) of driftwood catfish, Ageneiosus inermis Linnaeus, 1766 (Siluriformes: Auchenipteridae) from the Nanay River (Amazon River Basin, near Iquitos, Peru). It differs from all other aporocotylid genera by having a highly branched intestine comprising a central cecum that terminates immediately anterior to the ovary and that has numerous laterally directed diverticula. Kritsky platyrhynchi ( Guidelli, Isaac, and Pavanelli, 2002 ) n. gen., n. comb. (= Plehniella p.) is redescribed based on paratypes plus new specimens collected from the body cavity of the type host (porthole shovelnose catfish, Hemisorubim platyrhynchos Valenciennes, 1840) (Pimelodidae) from the nearby Itaya River. Kritsky differs from Sanguinicola Plehn, 1905 , Plehniella Szidat, 1951 , Nomasanguinicola Truong and Bullard, 2013 , and Cladocaecum by the combination of having a spinous anterior sucker, an intestine comprising 6 asymmetrical ceca, a lanceolate body, a straight vas deferens, an ovary with finger-like lateral projections, a small and spheroid oötype, numerous, minute, spheroid uterine eggs, and separate genital pores. An updated list of hosts, tissues infected, and geographic localities for the catfish blood flukes (9 spp.; 5 genera) is provided. This is the first report of a fish blood fluke infecting a member of Auchenipteridae and first proposal of a new genus of blood fluke (Schistosomatoidea) from South America in 64 yr. It brings the total number of Amazonian fish blood flukes to a mere 4 species.

New species of Proterometra (Digenea: Azygiidae) and its life cycle in the Chickasawhay River, Mississippi, USA, with supplemental observations of Proterometra autraini.

We describe Proterometra ariasae n. sp. based upon cercariae shed from a freshwater snail, Pleurocera sp., and adults infecting the buccal cavity of longear sunfish, Lepomis megalotis, captured from the Chickasawhay River, Mississippi, USA. We also provide supplemental observations of cercarial and adult paratypes of Proterometra autraini from the Au Train River, Michigan, USA. Sequence data for the ribosomal internal transcribed spacer 2 (ITS2) from adults and cercariae of the new species were identical. Adults of the new species differ from congeners by having (i) a markedly large body, (ii) a proportionally large oral sucker, (iii) ovoid testes, (iv) a strongly muscular and laterally expanded pars prostatica, (v) a uterus that is extensively convoluted between the ovary and ventral sucker (vi) and a vitellarium as long as the caeca and extending posteriad beyond the anterior margin of the testes. Cercariae of the new species differ from those of its congeners by having (i) a tail stem that is shorter than 10mm and that lacks a medial constriction, (ii) obcordate furcae that are wider than long, (iii) mamillae distributed throughout the anterior tail stem only, and (v) a proportionally small distome that has relatively few uterine eggs and remains withdrawn in the anterior tail stem region in actively swimming cercariae. This is the first report of Proterometra from Mississippi, the second description to employ morphology and sequence data to elucidate a life cycle for Proterometra, and the third species of Proterometra from an intermediate host not assigned to Elimia.

Blood flukes (Digenea: Aporocotylidae) infecting body cavity of South American catfishes (Siluriformes: Pimelodidae): two new species from rivers in Bolivia, Guyana and Peru with a re-assessment of Plehniella Szidat, 1951.

Plehniella Szidat, 1951 is emended based on new collections from South American long-whiskered catfishes. It is clearly differentiated from Sanguinicola Plehn, 1905 by lacking lateral tegumental body spines and by having 6 asymmetrical caeca. Plehniella sabajperezi sp. n. infects body cavity of Pimelodus albofasciatus (Mees) from the Demerara and Rupununi Rivers (Guyana) and Pimelodus blochii (Valenciennes) from Lake Tumi Chucua (Bolivia) and Napo River (Peru). It differs from Plehniella coelomicola Szidat, 1951 (type species) by having a thin-walled vas deferens that greatly exceeds the length of cirrus-sac and that joins the cirrus-sac at level of ovovitelline duct and ootype, an internal seminal vesicle that is absent or diminutive, and a cirrus-sac that is spheroid, nearly marginal, and envelops the laterally-directed distal portion of the male genitalia. Plehniella armbrusteri sp. n. infects body cavity of P. blochii from Lake Tumi Chucua (Bolivia). It differs from P. coelomicola and P. sabajperezi by having a relatively ovoid body, a massive intestine comprising caeca that are deeply-lobed to diverticulate and terminate in the posterior half of the body, a testis that flanks the distal tips of the posteriorly-directed caeca, and a proximal portion of the vas deferens that loops ventral to the testis. Small adults (Plehniella sp.) collected from body cavity of Pimelodus grosskopfii (Steindachner) from Cienega de Jobo and Canal del Dique (Colombia) differ from congeners by having a posteriorly-constricted body region, an anterior sucker with concentric rows of minute spines, an elongate anterior oesophageal swelling, short and wide caeca, and a male genital pore that opens proportionally more anteriad. This study nearly doubles the number of aporocotylids documented from South America Rivers and comprises the first record of a fish blood fluke from P. blochii, P. albofasciatus and P. grosskopfii as well as from Bolivia, Colombia, Guyana or Peru.

Skin lesions on yellowfin tuna Thunnus albacares from Gulf of Mexico outer continental shelf: Morphological, molecular, and histological diagnosis of infection by a capsalid monogenoid.

We characterize lesion-associated capsaline infections on yellowfin tuna, Thunnus albacares, in the Gulf of Mexico by comparing our specimens with published descriptions and museum specimens ascribed to Capsala biparasiticum and its synonyms: vouchers of C. biparasiticum from parasitic copepods; the holotype of Capsala neothunni; and vouchers of Capsala abidjani. Those from parasitic copepods differed by having a small, rounded body, large anterior attachment organs, closely spaced dorsomarginal body sclerites, small testes, and a short and wide testicular field. No morphometric feature in the holotype of C. neothunni ranged outside of that reported for the newly-collected specimens, indicating conspecificity of our specimens. The specimens of C. abidjani differed by having a large anterior attachment organ, few and dendritic testes, and a short, wide testicular field. Large subunit ribosomal DNA (28S) sequences grouped our specimens and Capsala sp. as sister taxa and indicated a phylogenetic affinity of Nasicola klawei. The haptoral attachment site comprised a crater-like depression surrounded by a blackish-colored halo of extensively rugose skin, with abundant pockmarked-like, irregularly-shaped oblong or semi-circular epidermal pits surrounding these attachment sites. Histology confirmed extensive folding of epidermis and underlying stratum laxum, likely epidermal hyperplasia, foci of weak cell-to-cell adhesions among apical malpighian cells as well as that between stratum germinativum and stratum laxum, myriad goblet cells in epidermis, rodlet cells in apical layer of epidermis, and lymphocytic infiltrates and melanin in dermis. The present study comprises (i) the first published report of this parasite from yellowfin tuna captured in the Gulf of Mexico-NW Atlantic Ocean Basin, (ii) confirmation of its infection on the skin (rather than on a parasitic copepod), (iii) the first molecular data for this capsaline, and (iv) the first observations of histopathological changes associated with a capsalid infection on a wild-caught epipelagic fish.

Proterometra epholkos sp. n. (Digenea: Azygiidae) from Terrapin Creek, Alabama, USA: molecular characterization of life cycle, redescription of Proterometra albacauda, and updated lists of host and geographic locality records for Proterometra spp. in North America.

Proterometra epholkos sp. n. asexually reproduces in the stream dwelling prosobranch, Elimia cf. modesta (Cerithioidea: Pleuroceridae) and infects the buccal cavity epithelium of spotted bass, Micropterus punctulatus (Perciformes: Centrarchidae) in the Coosa River (Terrapin Creek; N33°51'36.56″, W85°31'28.15″; Cleburne County, Alabama, USA). We characterize cercariae and adults of the new species using morphology and molecular sequence data and redescribe its morphologically similar congener Proterometra albacauda based on the holotype and paratype (USNPC Nos. 61229-30). The new species can be distinguished most easily from P. albacauda by the combination of having cercariae with long mamillae (>100µm) that encircle the tail stem anteriorly, that are restricted to 1 lateral column per body margin at midbody, and that are absent from the medial surface of the tail stem as well as by having adults with a partly extracecal uterus, a transverse metraterm occupying the space between the oral sucker and prostatic sac, and a vitellarium that is longer than the ceca and extends anteriad to the level of or beyond the posterior margin of the oral sucker. Sequence data from the ribosomal internal transcribed spacer 2 (ITS2; 251bp) did not reject the notion that the cercariae and adults we collected simultaneously from those infected, sympatric, individual snails and fish in Terrapin Creek were conspecific. Also provided herein for species of Proterometra are (i) taxonomic keys for cercariae and adults based on morphological and behavioral characteristics sourced from the published literature, (ii) updated lists of host records (prosobranchs and fishes) and geographic locality records for Proterometra spp., and (iii) synopses and assessments of the morphological features previously used to differentiate them. Proterometra macrostoma (type species), Proterometra melanophora, and Proterometra hodgesiana are species inquirendae; requiring new collections from type localities and hosts concomitant with neotype designations. P. macrostoma seems a repository for conspicuous, furcocystocercous cercariae shed from freshwater prosobranchs in eastern North American rivers and streams. The specific epithet "pinguis" associated with specimens purportedly infecting Esox lucius and deposited by JF Mueller is a nomen nudum. Proterometra guangzhouensis, Proterometra sillagae, Proterometra brachyuran, and Proterometra lamellorchis are incertae sedis. Significant barriers to characterizing biodiversity and distributions (host range and geographic distribution) of Proterometra spp. comprise a paucity of data on adult morphology, dubious species-level identification or a lack of information regarding prosobranch hosts, lack of molecular data for putative comparisons among fluke 'strains' and species as well as between cercariae and adults, lack of consistency in terminology, and indeterminate homology for key morphological features. Uncertainty about the providence and identity of, or absence of, accessioned museum materials of P. macrostoma, Proterometra catenaria, and P. hodgesiana together represent another fundamental problem. The present study comprises the first description of a new species of Proterometra in nearly 20years, first report of a species of the genus from the Coosa River (Mobile-Tensaw River Basin) and from these host species, and first use of molecular sequence data to elucidate a life cycle for a species of Proterometra.

Diversity and ancestry of flatworms infecting blood of nontetrapod craniates "fishes".

We herein review all published molecular studies (life history, taxonomy, and phylogeny) and summarize all GenBank sequences and primer sets for the "fish blood flukes". Further, by analysing new and all available sequence data for the partial D1-D2 domains of 28S from 83 blood fluke taxa, we explore the evolutionary expansion of flatworm parasitism in the blood of craniates. Based on this analysis, the blood flukes infecting marine bony fishes (Euteleostei) are monophyletic. The clade comprising the chondrichthyan blood fluke plus the marine euteleost blood flukes is the sister group to tetrapod blood flukes (spirorchiids and schistosomes). The innominate blood fluke cercariae from freshwater gastropods were monophyletic and sister to the clade comprising spirorchiids and schistosomes, but low nodal support indicated that they may represent a distinct blood fluke lineage with phylogenetic affinities also to fish blood flukes. Blood flukes that utilize gastropod intermediate hosts were monophyletic (unidentified gastropod cercariae+tetrapod blood flukes) and those utilizing bivalves and polychaetes were monophyletic (marine fish blood flukes). Low or no taxon sampling among blood flukes of basal fish lineages and primary division freshwater fish lineages are significant data gaps needing closure. We also note that no record of an infection exists in a hagfish (Myxiniformes), lamprey (Petromyzontiformes), or nontetrapod sarcopterygiian, i.e., coelacanth (Coelacanthimorpha) or lungfish (Dipnoi). The present phylogenetic analysis reiterated support for monophyly of Schistosomatidae and paraphyly of spirorchiids, with the blood flukes of freshwater turtles basal to those of marine turtles and schistosomes.

Blood flukes (Digenea: Aporocotylidae) of epipelagic lamniforms: redescription of Hyperandrotrema cetorhini from basking shark (Cetorhinus maximus) and description of a new congener from shortfin mako shark (Isurus oxyrinchus) off Alabama.

We emend the original generic diagnosis for Hyperandrotrema Maillard and Ktari, 1978 , and redescribe its type species Hyperandrotrema cetorhini Maillard and Ktari, 1978 (Digenea: Aporocotylidae Odhner, 1912), based on the holotype and 2 paratypes collected from the heart of basking shark (Cetorhinus maximus). We also describe Hyperandrotrema walterboegeri Orélis-Ribeiro and Bullard n. sp. based on light and scanning electron microscopy of 6 adult specimens collected from the heart of a shortfin mako shark (Isurus oxyrinchus Rafinesque, 1810) captured from Viosca Knoll (29°11.70'N, 88°33.32'W; 123 km southwest of Dauphin Island, Alabama), northern Gulf of Mexico. Hyperandrotrema spp. infect lamniforms and differ from all other nominal aporocotylids at least by having a ventrolateral field of robust C-shaped spines (rather than transverse rows of minute, shaft-like spines), an inverse U-shaped intestine with extremely elongate ceca terminating near the level of the excretory bladder, and a common genital pore that comprises the dorsal opening of a common genital atrium. Adults of the new species exceeded 12 mm in total length, making them the largest of the nominal fish blood flukes. The new species further differs from H. cetorhini by the combination of having an adult body that is 7-8 times longer than wide, large midbody tegumental spines measuring 25-38 µm long × 10-12 µm wide, a long vas deferens 4-5% of the body length, a testis 9-11 times longer than wide, and a large ootype 105-150 µm long × 85-105 µm wide. This is the first report of Hyperandrotrema from the Gulf of Mexico and the second aporocotylid species reported from an epipelagic elasmobranch. Our results demonstrate that ecologically related (epipelagic, marine) and phylogenetically related (Lamniformes) definitive hosts are infected by morphologically similar (congeneric) fish blood flukes.

Fulfilling Koch's postulates confirms the mycotic origin of Lethargic Crab Disease.

In the northeast region of the Brazilian coast, a disease has been causing massive mortalities of populations of the mangrove land crab, Ucides cordatus (L.) since 1997. The clinical signs of this disease, which include lethargy and ataxia, led to the disease being termed Lethargic Crab Disease (LCD). Evidence from a variety of sources indicates that there is an association between LCD and a new species of black yeast, Exophiala cancerae de Hoog, Vicente, Najafzadeh, Badali, Seyedmousavi & Boeger. This study tests this putative correlation through in vivo experiments. Disease-free specimens of U. cordatus were experimentally infected with Exophiala cancerae (strain CBS 120420) isolate. During the 30-day experimental period, only a single death was observed within the control crabs. However, at the end of this period, crabs that were inoculated once or three-times with mycelial elements and hyphae of E. cancerae had a 60% and 50% mortality rates, respectively (n = 6 and n = 5). These results support that the fungal agent is pathogenic and is the causative agent of LCD. Species-specific molecular markers confirm the presence of E. cancerae (strain CBS 120420) in recovered colonies and tissue samples from the infected animals. The experimentally infected crabs manifested signs (lethargy, ataxia and tetany) that were consistent to LCD-affected animals in the environment. These results fulfil Koch's postulates and the hypothesis that the tested strain of Exophiala cancerae is a causative agent of LCD is accepted.