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Cirrodrilus japonicus (Pierantoni, 1912) has not been identified since it was originally described from specimens removed from preserved Japanese crayfish that had been deposited in the Natural History Museum in Hamburg, Germany. A morphological comparison of the published description and recently discovered syntypes of C. japonicus from the Hamburg Museum with syntypes and newly collected material of Cirrodrilus ezoensis (Yamaguchi, 1934), supported the view that preservation artifacts in C. japonicus caused Prof. Yamaguchi to believe his well-preserved specimens were member of a separate species. Therefore, C. ezoensis becomes a junior synonym of C. japonicus.

Crayfishes and other invertebrates were collected during 2010 to 2016 from 519 sites located in the river basins of the Adour, Charente, Dordogne, Garonne, Loire, Seine, Rhône and Sélune in France. North American species included Pacifastacus leniusculus at 255 sites, Faxonius limosus at 206 sites, Procambarus clarkii at 56 sites, and the endemic Austropotamobius pallipes at two sites. However, branchiobdellidans were only recorded from 100 sites with 23 of these being sampled more than once, resulting in a total of 127 collections. The widely distributed western North American, P. leniusculus carried four of its endemic branchiobdellidan species: Cambarincola gracilis, C. okadai, Triannulata magna and Xironogiton victoriensis. X. victoriensis was found at the majority of sites, with C. okadai, C. gracilis, and T. magna at fewer locations. Although F. limosus was the second most numerous crayfish species collected, it did not carry any of its endemic North American branchiobdellidan species. However, it was found cohabiting with P. leniusculus at four sites but carried X. victoriensis at only one of these. European A. pallipes only occurred at two sites with individuals harboring X. victoriensis, although no cohabiting exotic crayfish were found. Crayfish were also absent from three sites where free-living X. victoriensis were recovered from substrate samples. Procambarus clarkii appeared at sites scattered across the country, while specimens with C. mesochoreus were restricted to the Adour drainage. This study has shown the widespread distribution of exotic branchiobdellidans in the wild and the virtual extinction of endemic species in France. In addition, we have provided the first European record of T. magna, and the first record of C. mesochoreus in France; the latter being only the second recording in Europe. With this comprehensive survey of their crayfish hosts in France, monitoring future exotic range expansions and endemic contraction or extinction can be traced. These data will be available to authorities for future planning in maintaining healthy freshwater bodies by reducing the damaging effects caused by exotic crayfishes.

The branchiobdellidan slide collection of Professor Hideji Yamaguchi was rediscovered in 1995; however, all of the written records associated with it appear to have been lost. The slide collection has been examined, cataloged and deposited in the Invertebrate Collection of the Hokkaido University Museum, Sapporo, Japan (ICHAM). The collection was found to contain whole mounted specimens of all 17 species described by Prof. Yamaguchi, together with specimens of three other Oriental species described after his death. In addition, mounted specimens of some of these species were designated syntypes. Many sectioned and stained specimens were also cataloged, but those were not identified to species at this time.

A new species of ectosymbiotic branchiobdellidan, Cirrodrilus iwakiensis sp. nov., is described from Cambaroides japonicus (de Haan, 1849), the endemic freshwater Japanese crayfish, collected in Aomori Prefecture, northern Honshu Island, Japan. The anatomical features used to identify C. iwakiensis are compared with those of its closest congener, C. nipponicus (Yamaguchi, 1932), as well as C. aomorensis (Yamaguchi, 1934) and C. tsugarensis Gelder and Ohtaka, 2000 distributed in the same region.

Despite the importance of aquatic symbionts in community organization, often little is known about the relative role of host and environmental characteristics on symbiont abundance. We investigated the importance of environmental and host physical characteristics on the abundance of the branchiobdellidan, Branchiobdella kozarovi , on a population of narrow-clawed crayfish, Astacus leptodactylus , in the Islamic Republic of Iran. Crayfish from four sites in the Aras Dam Reservoir were sampled on 12 occasions during 2009. Abundance of B. kozarovi was modeled against water temperature, crayfish length, mass, and sex after controlling for temporal and spatial effects. The most parsimonious model indicates that B. kozarovi abundance was primarily related to water temperature but also increased linearly with host body length. We found that omitting water temperature dramatically decreased model performance while omitting host physical characteristics decreased model performance marginally. We recommend that ecologists consider both environmental and host physical characteristics when monitoring aquatic symbionts such as branchiobdellidans, as both types of factors will provide insight into community dynamics and guide future management strategies.

Distribution of two ecologically similar but usually spatially separate ectosymbionts, branchiobdellidans (Annelida) and scutariellids (Platyhelminthes), on atyid shrimp (Neocaridina spp.) is reported from 18 localities in five Provinces of southeastern China. Prevalence was determined for the branchiobdellidan, Holtodrilus truncatus, found at seven locations, the scutariellid, Scutariella japonica, present at every site, and where cohabitation occurred. Both ectosymbionts showed a microhabitat predilection for the host's branchial chambers and instances of cohabitation occurred at all seven locations where H. truncatus were collected, although not on every shrimp. On-site observations of live hosts supporting both ectosymbionts showed that neither H. truncatus nor S. japonica reacted aggressively or defensively towards the other when in close proximity. Instances of imported Chinese Neocaridina spp. into central Honshu Island, Japan, almost certainly came from areas in southeast China identified in this study. These imported populations are predicted to spread northwards into the area where endemic Japanese branchiobdellidans occur.

Branchiobdellidans, or crayfish worms, are species-rich in the Appalachian area of the southeastern United States. Even so, the Great Smoky Mountains National Park (GSMNP) in the southern Appalachians has only one record of a branchiobdellidan species. As part of the All Taxa Biodiversity Inventory, we undertook a general survey of the branchiobdellidans in the GSMNP. Crayfish were collected from a total of 15 sites distributed across 11 watersheds in the GSMNP We identified a total of 10 species of branchiobdellidans: 1 species of Bdellodrilus, 1 species of Oedipodrilus, 2 species of Pterodrilus, 1 species of Xironodrilus, and 5 species of Cambarincola. The composition and number of species per site ranged from 0 to 6, and individual branchiobdellidan species occurrence ranged from 1 to 11 sites. Our results suggest that multiple factors affect distribution and occurrence on certain hosts. Study of specimens of Cambarincola holostomus Hoffman, 1963 enabled us to add new morphological characters ...

A re-description of Cambarincola bobbi Holt, 1988 is provided based on observations made during recent collections in the Cumberland River Watershed in Tennessee. The branchiobdellidan Pterodrilus robinae, a new species, is described, along with a refinement for identification of five additional Pterodrilus species. Diversity, sympatry, and range extensions of branchiobdellidans from three areas of the Cumberland River Watershed are reported.

Orconectes virilis (northern crayfish) were collected from 67 sites in Alberta, Saskatchewan, Manitoba, and far-western Ontario, Canada, and yielded 2 species of branchiobdellidans, Cambarincola vitreus and Cambarincola chirocephalus. This is the first report of branchiobdellidans in the Prairie Provinces. Cambarincola vitreus was distributed across the study area, but C. chirocephalus appeared to be restricted to southeastern Saskatchewan, southern Manitoba, and the site in western Ontario. Neither branchiobdellidan species was observed on crayfish in the Beaver River or the South Saskatchewan River and associated tributaries upstream (west) of Saskatoon, Saskatchewan, despite multiple sampling at these locations.

Preserved specimens of the crayfish Cambarus bartonii, Orconectes limosus, and Orconectes virilis from 27 locations in New Brunswick, and O. limosus from Freshwater Lake, Cape Breton Highlands National Park, Cape Breton Island, NS, Canada, were examined for branchiobdellidans. Three species of branchiobdellidans—Bdellodrilus illuminatus, Cambarincola fallax, and Xironogiton instabilis—were identified on C. bartonii. Only branchiobdellidan cocoons were recorded on O. limosus, and only X. instabilis was recovered from O. virilis in New Brunswick. The introduction of O. limosus and O. virilis into New Brunswick does not appear to have simultaneously introduced non-native branchiobdellidans. No branchiobdellidans were found on introduced O. limosus from Freshwater Lake, NS. This work provides the first records of branchiobdellidans occurring in the Maritime Provinces of Canada, and establishes the eastern limit for these ectosymbionts in North America. In addition, one specimen of C. bartonii was fou...

Symbionts are well known to have benefi cial and/or pathogenic effects on crayfi sh health, and as such assert direct impacts on freshwater ecosystems and commercial astaciculture. Several reviews (e.g., Vogt 1999, Evans and Edgerton 2002, Edgerton et al. 2002, Longshaw 2011, citations therein) provide valuable resources of information on crayfi sh symbionts ranging from viruses to arthropods. Although a useful starting point for interested researchers, these reviews may no longer accurately refl ect many recent shifts in our understanding of branchiobdellidan taxonomy, biology and hostsymbiont interactions. Branchiobdellidans, or crayfi sh worms (Fig. 23.1), comprise an order in which all known species are obligate ectosymbionts of freshwater crustaceans, primarily astacoidean crayfi shes. No free-living members are known (although see Holt 1973a, Timm 1991). Consequently, our understanding of branchiobdellidan ecology and evolution is inextricably intertwined with that of their crayfi sh hosts. Recent studies on branchiobdellidans have illuminated several errors and inaccuracies in earlier works. Consequently, our aim for this chapter is to provide an overview of current knowledge of branchiobdellidans, with a particular focus on aspects that are of interest to astacologists. For additional detail we direct readers to Gelder and Williams (2015).

Branchiobdellidans are leech-like, obligate ectosymbionts primarily associated with astacoidean crayfish. The branchiobdellidan-host symbiosis is common among freshwater habitats in North and Central America, the Euro-Mediterranean, and East Asia. Branchiobdellidan taxonomic diversity varies across the distribution of the order, with more than two-thirds of the 22 total genera and approximately 140 total species found in North and Central America. No free-living members of Branchiobdellida are known, although individuals have been observed independent of a host in the benthic zone. The ectosymbiont association is obligate as embryonic development – within a cocoon – will only occur on a live host. Branchiobdellidans are opportunistic omnivores with diet varying with habitat, season, etc. Species display high morphological convergence, perhaps as a function of a shared symbiotic nature, with ecological adaptability varying widely across the taxon.

This is the first article of branchiobdellidans on blue crabs, Callinectes sapidus, in Chesapeake Bay, MD, USA. The ectosymbionts consisted of sympatric populations of Cambarincola mesochoreus and Cambarincola pamelae living on the ventral body surface and in the gill chambers of blue crabs. The occurrence of branchiobdellidans in the upper bay region was documented at ten sites during August and late September 2003. Branchiobdellidans were found on blue crabs following a rainy summer when salinity levels fell below 3 ppt. The blue crabs move into the freshwater estuaries during the summer, where they enter the habitats of crayfishes; however, the mechanism of transfer from one crustacean host to another is not known.

This is the first report of two North American branchiobdellidans, Sathodrilus attenuatus Holt, 1981, and Xironogiton victoriensis Gelder and Hall, 1990, on the signal crayfish, Pacifastacus leniusculus (Dana, 1852) introduced into Japan from the Columbia River system, northwestern North America. Signal crayfish from 12 localities in eastern and northern Hokkaido, Japan, were examined and each supported S. attenuatus. In addition, an individual of this species was found on preserved material from Ishikawa Prefecture, central Honshu. All of these branchiobdellidans reported in Hokkaido most probably came from the original population of signal crayfish introduced into Lake Mashu, Hokkaido, Japan, in 1930. It is suggested that the use of non-pathogenic branchiobdellidans, when present, provides an easy method for tracing the spread of crayfishes around Japan and could also be applied in other countries and continents. Specimens of X. victoriensis were only found on crayfish in a stream at Akashina in Nagano Prefecture, central Honshu, Japan. Although the signal crayfish appears to be displacing the endemic Japanese crayfish, C. japonicus, no native branchiobdellidans were found on any of the introduced signal crayfish examined.

To investigate the phylogenetic relationships of leeches, branchiobdellidans, and acanthobdellidans, whole nuclear 18S rDNA and over 650 bp of mitochondrial cytochrome c oxidase subunit I were acquired from 101 annelids, including 36 leeches, 18 branchiobdellidans, Acanthobdella peledina, as well as 28 oligochaetes and combined with homologous data for 17 polychaete outgroup taxa. Parsimony analysis of the combined aligned dataset supported monophyly of leeches, branchiobdellidans, and acanthobdellidans in 100% of jackknife replicates. Monophyly of the oligochaete order Lumbriculida with Acanthobdellida, Branchiobdellida, and Hirudinea was supported in 84% of jackknife replicates. These results provide support for the hypotheses that leeches and branchiobdellidans are sister groups, that acanthobdellidans are sister to them, and that together with the family Lumbriculidae they all constitute a clade within Oligochaeta. Results support synonymy of the classes Clitellata and the more commonly used Oligochaeta. Leeches branchiobdellidans, and acanthobdellidans should be regarded as orders equal to their closest relatives, the order Lumbriculida.

Using 18S rDNA, mitochondrial cytochrome c oxidase subunit I and morphological characters, the Branchiobdellidae (Annelida, Clitellata) were shown to form a monophyletic group distinct from the leeches using two distant ‘oligochaetes’ as outgroups. The study used 20 branchiobdellid species from 14 genera in four subfamilies with these representing each of the taxon’s three distributional regions in the Holarctic realm. No monophyletic groups were found using the gene sequence data that related to either geographical regions or currently recognized subfamilies. However, two monophyletic groups were strongly supported; the two European species of Branchiobdella and the combination of Sathodrilus attenuatus and Xironogiton victoriensis. The latter pair is taxonomically diverse, but sympatric on Signal crayfish, Pacifastacus leniusculus, in California, USA.

Branchiobdellidans, or crayfish worms, are ectosymbiotic clitellate annelids associated primarily with freshwater crayfishes. The main objectives of our study were to infer a molecular phylogeny for the North American Branchiobdellida, examine its congruence with morphology-based hypotheses of relationships at the subfamily and genus level, and use our dataset to assess consistency of GenBank-archived branchiobdellidan sequences. We used nucleotide sequence data from two mtDNA genes (COI and 16S rDNA) and three nuclear genes (28S rDNA, 18S rDNA, and ITS1) to estimate phylogenetic relationships among 47 described and one undescribed species of Branchiobdellida. We recovered a monophyletic branchiobdellidan clade with generally short branch lengths, suggesting that a large portion of the taxon has likely undergone a recent and rapid radiation in North America. Results from our phylogenetic analyses indicate that current taxonomic groupings are largely unsupported by the molecular data. All four subfamilies are either paraphyletic or polyphyletic, and only three of seven sampled non-monotypic genera were monophyletic. We found a high rate (49%) of inconsistency in GenBank-archived sequences, over 70% of which can be attributed to field- or laboratory-based error.

Publisher Summary This chapter focuses on freshwater annelids of North America. Freshwater annelids (oligochaetes, branchiobdellidans, leeches, and acanthobdellids) can be found in both standing and flowing water and are often an important component of the aquatic food web. There are currently over 200 oligochaete species reported from North America that inhabit freshwater and estuarine bodies, including those in the lesser known groundwater and organic mud habitats. Most oligochaetes feed by ingesting sediment, but several North American genera prey on other worms or on a variety of small invertebrates. Branchiobdellidans or crayfish worms are leech-like ectosymbionts living primarily on astacoidean crayfish. 15 genera and 107 species of Branchiobdellidan are reported from North America. Leeches (Hirudinida), an important component of the benthos of most freshwater lakes, ponds, and quieter flowing sections of streams and rivers, can also be found. There are 76 leech species currently known from North America, most of which prey on chironomids, oligochaetes, amphipods, and molluscs. The chapter describes the ecology, life history, anatomy, morphology, ecology, evolution, and physiology of oligochaetes, branchiobdellidans, leeches, and acanthobdellids found in North America.

Xironogiton victoriensis n.sp. is described from the crayfish Pacifastacus leniusculus leniusculus on Vancouver Island, British Columbia, Canada. Collections of P. l. leniusculus from Goldstream River, and Colquitz Creek, Victoria, and Burdette Creek, Burnaby, Vancouver, in southwestern British Columbia yielded Cambarincola fallax, C. gracilis, C. montanus, and Xironogiton kittitasi. Specimens of each species of Xironogiton have been examined and a taxonomic key for the genus has been constructed. The information was also used in a Wagner analysis of Xironogiton which showed the genus to be a monophyly.

Analyses using PAUP (phylogenetic analysis using parsimony) were conducted on a matrix of 24 taxa and 26 characters. The taxa included generalised descriptions of a haplotaxid and a lumbriculid oligochaete as outgroups with a hypothetical branchiobdellidan ancestor and 21 genera as ingroups. The branchiobdellidan taxon is a monophyly, and using anatomical characters only, is composed of three suprageneric assemblages. The taxonomic rank of the taxon and assemblages cannot be determined until they have been compared with cladistic analyses on other closely related clitellate groups. In the meantime the currently accepted ordinal rank of Branchiobdellida and the major branchiobdellidan families should continue to be used, with the latter reflecting the assemblages of the genera in our analyses: Branchiobdellidae (including Holtodrilus n.gen., Sinodrilus n.gen., and Xironodrilus), Bdellodrilidae (including Caridinophila and Hidejiodrilus n.gen.), and Cambarincolidae. An analysis with two zoogeographical characters in the matrix caused the genera to be divided into their respective North American and Eurasian groups; however, the North American Triannulata appeared constantly in the latter group. The genera in the Branchiobdellidae, as defined by us, are found in both geographical regions, and predictably the assemblage was split in two.

The zoogeographical distribution of branchiobdellidans (Annelida) and temnocephalidans (Platyhelminthes), ectosymbiotic on freshwater crustaceans, is reviewed and revised. In the areas where the Holarctic branchiobdellidans and Gondwanian temnocephalidans overlap, distributions of species and their respective hosts are reviewed in detail. Specimens of the branchiobdellid, Branchiobdella astaci, and the scutariellid temnocephalidan, Bubalocerus pretneri, were allowed to meet in vitro on the dorsal carapace of a crayfish, Austropotamobius pallipes. This usually resulted in the scutariellid being ingested by a branchiobdellid. Specimens of B. astaci were placed in contact with the host of B. pretneri, Troglocaris sp., a cave-dwelling shrimp and the branchiobdellid immediately moved away from the shrimp.

A brief review of the taxonomic history and integrity of selected North American branchiobdellidans is given to clarify their current status. The zoogeographical distribution of branchiobdellidans on the North American continent is presented based on published reports and information in the Catalog of the National Museum of Natural History, Smithsonian Institution, Washington, DC. These data are tabulated by species with locations referenced to zoogeographical subregions, political units of provinces, states, or countries, and source citations. Distributional anomalies of certain taxa are discussed.

Revision of the literature concerning Agriodrilus (Oligochaeta, Lumbriculidae) and Acanthobdella (Acanthobdellida), both supposedly intermediate links in the traditional single line of evolution between lumbriculids, branchiobdellidans, and leeches, supports the alternative hypothesis of an independent origin of most if not all of these groups. Discovery of Phagodrilus, a lumbriculid that is clearly convergent with Agriodrilus in terms of the pharynx, lends further support to this concept. No decision as to the rankings of the various taxa can be made until new material of Acanthobdella is examined and all variable characters are used to determine synapomorphic character states and monophyletic groupings within this complex.

Three jars from the Hamburg Museum contained specimens of Branchiobdella minuta,presumably from the original Pierantoni (1912) material, and Cirrodrilus cirratus and C. uchidai from Yamaguchi’s (1932a) collection. The head of a syntype of B. minuta was described and B. cheni becomes its junior subjective synonym. One specimen each of C. cirratus and C. uchidai was sectioned and described, particularly the male genitalia. The diet of all three branchiobdellids consists of microorganisms. In Cirrodrilus sp. basic protein granules were demonstrated in the gland cells of the intestine and its chloragogen cells. The peristomial and lateral epidermal gland cell secretions were characterized histoehemically.

There is very little information on the genus Branchiobdella and the species relationships with their freshwater crayfish hosts in Croatia. Therefore, a base-line study was needed so that future changes in available habitat brought about by urban development and the probable introduction of non-native species can be accurately assessed. This investigation used preserved freshwater crayfish collected from across Croatia between 1995 and 2005 as its source of the ectosymbionts. Crayfish species included Astacus astacus, A. leptodactylus, Austropotamobius pallipes, A. torrentium, and the allochtonous North American species, Orconectes limosus. Only native European species of branchiobdellids were found: Branchiobdella astaci, B. parasita, B. pentodonta, B. hexodonta, B. italica, and B. balcanica, and this is the first report on the occurrence of these species, apart from B. italica, in Croatia. The distribution of these branchiobdellidans is compared with climatic and river drainage systems, and literature reports of populations in other countries in the region.

This is the first report of branchiobdellids (Annelida: Clitellata) from Maine. Twenty-seven aquatic sites were surveyed in Aroostook County, Maine and two species of crayfish were collected. Cambarus bartonii bartonii occurred in all but two sites and supported three species of branchiobdellids, Bdellodrilus illuminatus, Cambarincola fallax, and Xironogiton instabilis; in most cases, specimens of all three species occurred on the same host. Bdellodrilus illuminatus was restricted to the branchial chambers, X. instabilis to the chelipeds, and C. fallax to the oral and ventral surfaces of the body. Specimens of Orconectes virilis were collected from two sites and only supported B. illuminatus. The reported distribution of branchiobdellid worms on the North American continent extends north from Costa Rica into southern Canada (Holt, 1973). Early reports of geographical occurrence were reviewed in a monograph by Goodnight (1940). Subsequently, our knowledge of branchiobdellid taxonomy and distribution has been greatly extended (for reviews see Holt, 1965, 1968, 1975). However, information on ecology and interactions of host/branchiobdellid associations are less well understood (Bishop, 1968; Hobbs et al., 1967; McManus, 1960; Young, 1966). In the northeastern United States, only the state of New York and adjacent surrounding areas have received attention (reviewed by Hoffman, 1963). This investigation was undertaken to ascertain the species distribution of branchiobdellids in Aroostook County, Maine as a preliminary step to future studies of their ecology and physiology. MATERIALS AND METHODS Each collection site (Table I) was sampled by "kick-searching" the bottom once during the period from mid-June to mid-September 1985 for up to 30 min; a maximum of six crayfish was taken from each site. The crayfish were placed in 10% formalin for subsequent identification (Crocker, 1979; Pennak, 1978) and examination for the presence, and then identification, of branchiobdellid worms (Hoffman, 1963; Holt, 1974; Pennak, 1978). Identification was enhanced by staining specimens with alum carmine, dehydration in graded ethanol solutions, clearing in xylene, and mounting in Canada balsam (Humason, 1979). The number of individuals representing each branchiobdellid species was noted; such notations included specimens from the host and in the 1 We thank Prof. Denton W. Crocker, for identification of crayfish species, and Prof. Perry C. Holt and Dr. A. M. Gorman for reading the manuscript. This investigation was supported by National Science Foundation Grant PCM 83-16396 and a Faculty Research Grant-in-aid from the University of Maine at Presque Isle to S.R.G. TRANS. AM. MICROSC. SOC., 106(1): 85-88. 1987. ? Copyright, 1987, by the American Microscopical Society, Inc. This content downloaded from 157.55.39.58 on Thu, 23 Jun 2016 05:34:39 UTC All use subject to http://about.jstor.org/terms TRANS. AM. MICROSC. SOC. bottom debris from the collecting jars. One crayfish from each collection site was retained as a taxonomic reference specimen. Additional crayfish specimens were collected and maintained in the laboratory; movements and distributions of their branchiobdellid symbionts were observed.