Northeastern Naturalist Vol. 26, No. 1 L. Lukas, P.G. Weaver, and B.W. Williams 2019 155 2019 NORTHEASTERN NATURALIST 26(1):155–167 Distributions of Two Groups of Obligate Crayfish Ectosymbionts—Branchiobdellidans and Entocytherid Ostracods—in New England Laura C. Lukas1, Patricia G. Weaver2,*, and Bronwyn W. Williams1 Abstract - North American crayfishes are hosts for 2 major groups of obligate ectosymbionts, namely annelids of the order Branchiobdellida and ostracods of the family Entocytheridae. These symbionts are widely distributed across the continent, coincident with their typical hosts; however, the diversity and distribution of both groups are poorly known in much of the northeastern US. We examined 93 crayfishes collected from 30 sites across New England for the presence of branchiobdellidans and entocytherids. We recovered 4 branchiobdellidan and 3 entocytherid species, with both groups displaying curiously dissimilar distributions. We present here the first published records of the branchiobdellidan Cambarincola vitreus in New England, the first record of the Procambarus acutus (White River Crayfish) from New Hampshire, and begin to fill substantial gaps in the known distribution of 2 major groups of obligate crayfish ectosymbionts. Introduction Crayfishes in North America are frequently associated with 2 groups of obligate ectosymbionts, annelids of the order Branchiobdellida and ostracods of the family Entocytheridae. The obligate nature of the symbiosis of both branchiobdellidans and entocytherids is reproductive, wherein embryonic development usually occurs only if the cocoon is attached to a live host (Young 1966, 1971). Although the highest diversity of both groups occurs in North America, coincident with their typical hosts, crayfishes, neither branchiobdellidans nor entocytherids are restricted to the continent. Branchiobdellida is composed of a family, 4 subfamilies, 22 genera, and more than 150 species distributed across the Holarctic (Gelder and Williams 2016). Entocytheridae, with 5 subfamilies, 35 genera, and 213 species, displays a disparate global distribution, and is found in Europe, Africa, Asia, Australasia, and Central and North America (Williams and Weaver 2018). New England, as a region covered entirely by ice during the maximum extent of the Wisconsinan Glaciation (~26,000 ya; Dyke and Prest 1987, Dyke et al. 2002), supports a surprisingly high diversity of crayfishes. Twelve crayfish species have been reported from the 6 New England states (Aiken 1965, Beauchene 2011, Crocker 1979, Gaurino et al. 2012, Hobbs 1989, Martin 1997, Mathews and Warren 2008, Smith 1982), including Cambarus bartonii (Fabricius) (Common Crayfish), Cambarus robustus Girard (Big Water Crayfish), Faxonius immunis (Hagen) 1North Carolina Museum of Natural Sciences, Research Laboratory, 1671 Gold Star Drive, Raleigh, NC 27699. 2North Carolina Museum of Natural Sciences, 11 West Jones Street, Raleigh, NC 27601. *Corresponding author - trish.weaver@naturalsciences.org. Manuscript Editor: Joshua Ness Northeastern Naturalist 156 L. Lukas, P.G. Weaver, and B.W. Williams 2019 Vol. 26, No. 1 (Calico Crayfish), Faxonius limosus (Rafinesque) (Spiny Cheek Crayfish), Faxonius propinquus (Girard) (Northern Clearwater Crayfish), Faxonius quinebaugensis (Mathews and Warren) (Quinebaug Crayfish), Faxonius neglectus (Faxon) (Ringed Crayfish), Faxonius obscurus (Hagen) (Allegheny Crayfish), Faxonius rusticus (Girard) (Rusty Crayfish), Faxonius virilis (Hagen) (Virile Crayfish), Procambarus acutus (Girard) (White River Crayfish), and Procambarus clarkii (Girard) (Red Swamp Crayfish). Of these, only the former 6 are considered native (e.g., Crocker 1979), whereas the latter 6 are considered non-native to the region (Beauchene 2011, Crocker 1979, Gaurino et al. 2012, Martin 1997). Nearly all of the crayfish species listed above are known hosts for both branchiobdellidans and entocytherids (e.g., Gelder et al. 2002, Hart and Hart 1974); thus, we might expect a relatively high diversity of these symbionts in New England, similar to that of their hosts. Yet, the diversity and distribution of branchiobdellidans and entocytherids in New England is generally not well known. This is particularly true for Entocytheridae; only a single published record exists of an entocytherid in New England (Fig. 1A). Hart and Hart (1974) listed Donnaldsoncythere donnaldsonensis (Klie) occurring on Common Crayfish from Beau Lake on the St. Francis River, Aroostook County, northern Maine. The paucity of records of entocytherids in New England may reflect a true absence of these ectosymbionts, or it may solely be due to a lack of targeted studies in the region. Entocytherids have been reported elsewhere in the northeastern US (Fig. 1A), suggesting that the latter scenario is the most likely. Gall and Jezerinac (1998) recovered Rhadinocythere serrata (Hoff) from Cambarus diogenes Girard (The Devil Crayfish) in western New York. Shelton et al. (2016) recovered D. cayuagensis Hobbs and Walton from eastern New York, and D. donnaldsonensis from Big Water Crayfish and Common Crayfish in eastern New York and from Common Crayfish in northern New Jersey . The diversity and distribution of branchiobdellidans in New England is much better known than that of entocytherids, primarily a result of efforts by Dr. Stuart Figure 1 (following page). (A) Map of the distribution of entocytherid ostracods in New England and adjacent areas of the Northeastern US based on data retrieved from Mestre and Mesquita-Joanes (2018), Gall and Jezerinac (1998), Shelton et al (2016), and results of this study. Dark grey circles denote localities where entocytherids were previously reported. Stars denote sites where we recovered entocytherids during this study. Hollow diamonds denote sites where we collected crayfishes, but with no associated entocytherids. (B) Map of the distribution of branchiobdellidans in New England and adjacent areas of the Northeastern US compiled from data in Gelder and Smith (1987), Gelder et al. (2001), Gelder et al. (2009), Hoffman (1963), unpublished records of specimens housed in the North Carolina Museum of Natural Sciences (NCSM) Non-molluscan Invertebrate Collection, and results of this study. Dark grey circles denote localities where branchiobdellidans were previously reported. Hollow circles denote sites where crayfishes were previously collected, but no branchiobdellidans found. Stars denote sites where we recovered branchiobdellidans during this study. Empty diamonds denote sites where we collected crayfishes, but with no associated branchiobdellidans. (C) Magnified view of the Housatonic River system in Connecticut and Massachusetts, showing localities with both branchiobdellidans and entocytherids (B, E), branchiobdellidans only (B), entocytherids only (E), or no observed symbionts (Ø). Northeastern Naturalist Vol. 26, No. 1 L. Lukas, P.G. Weaver, and B.W. Williams 2019 157 Figure 1. [Caption is on the preceding page.] Northeastern Naturalist 158 L. Lukas, P.G. Weaver, and B.W. Williams 2019 Vol. 26, No. 1 Gelder (professor emeritus, University of Maine at Presque Isle). Branchiobdellidans have been reported from all New England States except Rhode Island (Fig. 1B; Gelder and Smith 1987, Gelder et al. 2001, Hoffman 1963). Six branchiobdellidan species are known to occur in the region, including Cambarincola philadelphicus (Leidy), Cambarincola mesochoreus Hoffman, Cambarincola fallax Hoffman, Bdellodrilus illuminatus (Moore), Xironogiton instabilis (Moore), and Pterodrilus missouriensis Holt. However, perceived gaps in the distribution of these worms remain in several areas of New England, as a result of a lack of sampling, or alternatively, genuine absence. The primary goal of this study is to fill gaps in the known distribution of crayfish symbionts, both entocytherids and branchiobdellidans, in New England, and to establish a baseline for future symbiont st udies. Methods We collected crayfishes in August of 2016 and 2017 from a total of 28 sites in Connecticut, Maine, Massachusetts, and New Hampshire. We added specimens to our study from 2 additional sites, 1 each in Vermont and New Hampshire, sampled by B.W. Williams in 2012. We collected crayfishes by hand or using kick nets for 1 person-hour, and fixed samples on site in 80% ethanol. When we captured more than 1 species at a location, we fixed specimens of each species in separate containers to retain information pertaining to host–symbiont association. In the laboratory, we used a dissecting microscope to inspect the external surface of each crayfish for the presence of symbionts. We carefully lifted the rear of the carapace from the body of each specimen, allowing examination of the gill chambers. We used a pipet to gently remove symbionts from the host and from the detritus at the bottom of the jar; samples were preserved separately in 95% ethanol. We made permanent slide mounts of branchiobdellidans and entocytherids recovered during this study for identification and vouchering. We took all specimens through a stepwise dehydration series in ethanol, cleared using methyl-salicylate, and then mounted them on glass slides in Canada balsam. We examined slidemounted specimens using differential interference contrast (DIC) on a Nikon Ni microscope. We used the keys and descriptions in Hart and Hart (1974), Hoffman (1963), Holt and Opell (1993), and where needed, references therein to make identifications. All specimens examined during this study are housed in the North Carolina Museum of Natural Sciences (NCSM) Non-Molluscan Invertebrate Collection. Results We recovered 5 crayfish species from the 30 sites sampled for this study, including Big Water Crayfish, Spiny Cheek Crayfish, Rusty Crayfish, Virile Crayfish (sensu lato [s. l.]; see discussion), and White River Crayfish (Table 1). We collected Spiny Cheek Crayfish from 11 localities in the Housatonic and Connecticut river basins of western and central Connecticut and central Massachusetts, and the Piscataqua/Presumpscot River Basin in southern New Hampshire and Maine. We found Virile Crayfish (s. l.) at 9 sites in the upper Housatonic and Connecticut river Northeastern Naturalist Vol. 26, No. 1 L. Lukas, P.G. Weaver, and B.W. Williams 2019 159 Table 1. Localities in New England sampled during this study, including crayfish hosts collected and, where present, entocytherid ostracods and branchiobdellidan associates. [Table continued on following page.] Locality Lat. (°N) Long. (°W) Host Entocytherid Branchiobdellidan CT, Litchfield County, Blackberry River 42.01143 73.30734 Faxonius rusticus Thermastrocythere riojai Cambarincola philadelphicus CT, Litchfield County, East Aspetuck River 41.64651 73.38342 Faxonius rusticus None None CT, Litchfield County, Housatonic River 41.95727 73.36994 Faxonius rusticus Thermastrocythere riojai Cambarincola mesochoreus CT, Litchfield County, Nonnewaug River 41.61276 73.17155 Cambarus robustus Donnaldsoncythere None donnaldsonensis CT, Litchfield County, Shepaug River 41.56345 73.32804 Faxonius rusticus Ankylocythere sinuosa Cambarincola mesochoreus CT, Litchfield County, Weekeepeemee River 41.62711 73.22367 Cambarus robustus Donnaldsoncythere None donnaldsonensis CT, Litchfield County, West Aspetuck River 41.61576 73.42116 Cambarus robustus Donnaldsoncythere None donnaldsonensis, Thermastrocythere riojai CT, Litchfield County, West Aspetuck River 41.61576 73.42116 Faxonius rusticus Donnaldsoncythere Cambarincola new donnaldsonensis, species (unpubl.) Thermastrocythere riojai CT, Middlesex County, Coginchaug River 41.52676 72.69585 Faxonius limosus None None CT, Middlesex County, Coginchaug River 41.52676 72.69585 Procambarus acutus None None CT, Middlesex County, Eightmile River 41.48357 72.34138 Faxonius limosus None None CT, Middlesex County, Hammonassett River 41.33090 72.61436 Faxonius limosus None None CT, Middlesex County, Pond Meadow Brook 41.37754 72.59428 Faxonius limosus None None CT, New Haven County, Pomperaug River 41.47094 73.25481 Cambarus robustus None Cambarincola mesochoreus CT, New Haven County, Pomperaug River 41.47094 73.25481 Faxonius limosus None Cambarincola mesochoreus CT, New Haven County, Naugatuck River 41.48590 73.05383 Faxonius rusticus None None Northeastern Naturalist 160 L. Lukas, P.G. Weaver, and B.W. Williams 2019 Vol. 26, No. 1 Table 1, continued. Locality Lat. (°N) Long. (°W) Host Entocytherid Branchiobdellidan MA, Berkshire County, Green River (Egremont) 42.20000 73.43647 Faxonius virilis (s.l.) Unidentified A1 female/ None juvenile MA, Berkshire County, Housatonic River 42.27776 73.35924 Faxonius rusticus Thermastrocythere riojai Cambarincola mesochoreus MA, Berkshire County, Konkapot River 42. 18074 73.24818 Faxonius virilis (s.l.) None Cambarincola vitreus MA, Hampshire County, Batchelor Brook 42.27744 72.56213 Faxonius limosus None None MA, Hampshire County, Batchelor Brook 42.27744 72.56213 Procambarus acutus None None MA, Franklin County, Deerfield River 42.52584 72.63168 Faxonius limosus None None MA, Franklin County, Deerfield River 42.52584 72.63168 Faxonius virilis (s.l.) None None MA, Franklin County, Green River (Greenfield) 42.69815 72.66477 Faxonius virilis (s.l.) None None MA, Franklin County, Hinsdale Brook 42.62952 72.64542 Faxonius virilis (s.l.) None None MA, Middlesex County, River Meadow Brook 42.55400 71.35295 Faxonius virilis (s.l.) None None ME, Cumberland County, Moose Pond 44.06627 70.80580 Faxonius limosus None None ME, Cumberland County, Sebago Lake 43.89901 70.47459 Faxonius virilis (s.l.) None Cambarincola mesochoreus ME, Cumberland County, Sebago Lake 43.89901 70.47459 Faxonius limosus None Cambarincola mesochoreus ME, Oxford County, Cushman Pond 44.22008 70.83612 Faxonius virilis (s.l.) None None ME, Oxford County, East Branch Nezinscot River 44.35579 70.37563 Faxonius virilis (s.l.) None Cambarincola mesochoreus ME, York County, Salmon Falls River 43.55283 70.95353 Faxonius limosus None None ME, York County, Salmon Falls River 43.55283 70.95353 Faxonius virilis (s.l.) None None NH, Belknap County, Poorfarm Brook 43.574788 71.35548 Faxonius virilis (s.l.) None None NH, Rockingham County, Lamprey River 43.04030 71.19975 Faxonius limosus None None NH, Rockingham County, Lamprey River 43.04030 71.19975 Faxonius virilis (s.l.) None None NH, Rockingham County, Towle Brook 42.9632 71.2267 Procambarus acutus None None VT, Orange County, Wells River 44.15208 72.06953 Faxonius virilis (s.l.) None Cambarincola vitreus Northeastern Naturalist Vol. 26, No. 1 L. Lukas, P.G. Weaver, and B.W. Williams 2019 161 basins in Massachusetts and Vermont, the Merrimack River Basin in New Hampshire, the Piscataqua/Presumpscot River Basins in New Hampshire and Maine, and the Androscoggin River Basin in south-central Maine. We collected Rusty Crayfish from 7 localities in the Housatonic River Basin in western Connecticut and Massachusetts. We found Big Water Crayfish at 4 sites in the Housatonic River system, all in Connecticut. We recovered White River Crayfish at 2 sites in the Connecticut River Basin in Connecticut and Massachusetts, and a third in the Merrimack River Basin in southern New Hampshire. We examined a total of 93 crayfishes for the presence of obligate ectosymbionts, and found branchiodellidans at 10 of 30 sampled sites (Fig. 1B). We recovered 4 species of branchiobdellidan from 5 host species. We observed Cambarincola mesochoreus on Rusty Crayfish, Big Water Crayfish, and Spiny Cheek Crayfish in the Housatonic River Basin, Spiny Cheek Crayfish and Virile Crayfish (s. l.) in the Piscataqua/Presumpscot River Basin in Maine, and and Virile Crayfish (s. l.) in the Androscoggin River Basin in south-central Maine. We recovered Cambarincola vitreus Ellis (Fig. 2A) from Virile Crayfish (s. l.) in the upper Housatonic River Basin in Massachusetts and upper Connecticut River Basin in Vermont. We observed Cambarincola philadelphicus (Fig. 2B) on Rusty Crayfish at a single site in the Housatonic River Basin in northwestern Connecticut. We also recovered an as yet undescribed species of Cambarincola from Rusty Crayfish at a site in the Housatonic River Basin in western Connecticut. We observed only 1 species of branchiobdellidan at any given site, regardless of the number of host species present. Of the 30 localities from which we collected crayfish for this study, only 8 sites, all within the Housatonic River Basin, produced entocytherid ostracods. Further, only Big Water Crayfish, Rusty Crayfish, and Virile Crayfish (s. l.) were found to be hosts (Table 1, Fig. 1A). We detected D. donnaldsonensis (Fig. 2C) on Big Water Crayfish at 2 sites in Connecticut, as well as co-occurring on both Big Water Crayfish and Rusty Crayfish in the West Aspetuck River. We recovered Thermastrocythere riojai (Hoff) (Fig. 2D) from Rusty Crayfish at the West Aspetuck River site, as well as 3 additional sites in northwestern Connecticut and western Massachusetts. We observed Ankylocythere sinuosa (Rioja) (Fig. 2E) on Rusty Crayfish from the Shepaug River, CT. We found 2 entocytherids, an A1 female and an A3 juvenile, on Virile Crayfish (s. l.) from the Green River, MA, that were unidentifiable to genus or species. We did not observe entocytherid ostracods on any crayfishes collected from Maine, Vermont, or New Hampshire. Discussion The distributions of entocytherids and branchiobdellidans across our study area differed substantially both from expectation and each other. We observed entocytherids on crayfishes only within the Housatonic River system of western Connecticut and Massachusetts. This finding suggests that entocytherids did not colonize the New England region coincident with their crayfish hosts following retreat of the Laurentide ice sheet. Entocytherids may not have been present, or survived, on crayfishes relegated to refugia during the Wisconsinan Glaciation. Northeastern Naturalist 162 L. Lukas, P.G. Weaver, and B.W. Williams 2019 Vol. 26, No. 1 Alternatively, temperature, salinity, or other environmental conditions may have selectively impeded colonization of these ostracods into New England drainages. Interestingly, opportunistic observations suggest entocytherids are more tolerant of environmental fluctuation than branchiobdellidans (B.W. Williams, unpubl. data). Further, entocytherids are commonly found on crayfishes in estuarine habitats along the Coastal Plain (e.g., Hart and Hart 1974, Hobbs 1978). New England is not the only region in which the range limit of entocytherids differs from that of their crayfish hosts; Thermastrocythere riojai appeared to be absent from much Figure 2. Examples of crayfish symbionts observed during this study including (A) Cambarincola vitreus, (B) C. philadelphicus, (C) Donnaldsoncythere donnaldsonensis, (D) Thermastrocythere riojai, and (E) Ankylocythere sinuosa. (F) False mating of a male D. donnaldsonensis with a male T. riojai. All scale bars are 100 μm. Northeastern Naturalist Vol. 26, No. 1 L. Lukas, P.G. Weaver, and B.W. Williams 2019 163 of the westernmost distribution of Virile Crayfish in the Prairie Provinces of Canada (Williams et al. 2011). Gelder et al. (2001) considered branchiobdellidans to be widespread throughout New England, a pattern that is in sharp contrast to our current understanding of the regional distribution of entocytherid ostracods. Our collections extend the reported distribution of branchiobdellidans north into northern Vermont, and south and east into eastern Connecticut and southeastern Massachusetts. Surprisingly, we failed to recover branchiobdellidans at numerous sites in central New England, most notably throughout the middle and lower Connecticut River drainage, and sites sampled in New Hampshire and southern Maine. Several of these localities are in close proximity to sites from which branchiobdellidans were reported by Gelder et al. (2001). Crayfishes examined by Gelder et al. (2001) were collected in the 1950s, 1970s, and 1980s, and as such, represent a historical snapshot of the diversity and distribution of these taxa and their branchiobdellidan associates. Our observations suggest that branchiobdellidans may have been extirpated from several waterways of New England, although the cause and true extent remain unclear. New England rivers were among the most polluted rivers in the country in the early to mid-20th century (Robinson et al. 2003); by the early 1970s the Connecticut River was so polluted it was referred to as a “landscaped sewer” (USEPA 2000). Branchiobdellidans are less tolerant of environmental perturbation than their crayfish hosts (B.W. Williams, unpubl. data), and may have succumbed to the effects of pollution. Other factors that likely shaped observed patterns of symbiont distribution include the effects of introduced and invasive crayfishes. The high diversity of crayfishes reported from New England is in large part due to species introductions. Indeed, half of the known crayfish species in the region are considered non-native, (e.g., Crocker 1979, Gaurino et al. 2012, Martin 1997). Of the remaining 6 species, all considered native in New England, most are believed to have been translocated intra-regionally (Crocker 1979), and in some cases extralimitally (e.g., Gaurino et al. 2012). Crayfish symbionts often, but not always, accompany their introduced hosts. We recovered T. riojai and A. sinuosa from the invasive crayfish Rusty Crayfish. Both entocytherids are known from the Interior Plains of North America, and were likely introduced into New England in conjunction with their hosts. In a reach of the West Aspetuck River in eastern Connecticut where native Big Water Crayfish co-occurred with invasive Rusty Crayfish, we observed T. riojai and D. donnaldsonensis on both crayfish species, indicating that these symbionts were able to exchange hosts. Close interaction between symbiont species was apparent in our observation of false mating between a sclerotized adult male D. donnaldsonensis and a non-sclerotized adult male T. riojai (Fig. 2F). Although a humorous case of mistaken identity, lack of sclerotization is likely the cue for mating behavior (Weaver and Williams 2016, 2017); the smaller size of the T. riojai adult male may have allowed the adult male of much larger D. donnaldsonensis to mistake it for an A-1 female. Donnaldsoncythere donnaldsonensis, which we recovered from the Housatonic River system, is one of the most widespread entocytherid species in North America, Northeastern Naturalist 164 L. Lukas, P.G. Weaver, and B.W. Williams 2019 Vol. 26, No. 1 ranging from northern Georgia to Indiana and east into New England (Hart and Hart 1974, Shelton et al. 2016). The Housatonic River drainage appears to delimit the northeastern edge of the contiguous range of D. donnaldsonensis. The record of D. donnaldsonensis from Common Crayfish in Beau Lake, northern Maine (Hart and Hart 1974) seems to be an aberrant and isolated occurrence, suggesting that the species may have been translocated from elsewhere on an introduced host. Virile Crayfish and Spiny Cheek Crayfish are believed to have been moved extensively into and around New England as bait or forage for sport fishing and for culinary purposes (Crocker 1979, Faxon 1885), and may have been accompanied by their symbionts, which could then transfer to other resident hosts, for example, Common Crayfish. However, we did not encounter C. bartonii during our survey. Therefore, in lieu of additional targeted sampling efforts, we cannot rule out that D. donnaldsonensis is present on Common Crayfish throughout New England, yet has not spread to additional host species. Indeed, the distribution of D. donnaldsonensis along the Appalachian Mountain chain in large part mirrors that of C. bartonii, suggesting a potential shared biogeographic history. Of the 6 total branchiobdellidan species previously reported from New England (Gelder and Smith 1987, Gelder et al. 2001), we recovered only 2: C. mesochoreus and C. philadelphicus. We did not encounter X. instabilis, C. fallax, or B. illuminatus, and attribute this situation to under-sampling of the high-gradient, mountain habitats and host species (Common Crayfish) with which these bra nchiobdellidans are typically associated. We also did not observe P. missouriensis, which was reported by Gelder et al. (2001) as an unexpected and singular occurrence in southern Maine, almost undoubtedly the result of introduction. We did recover C. vitreus on Virile Crayfish (s. l.) from the Konkapot River in eastern Massachusetts and Wells River, northern Vermont. These are the first published records C. vitreus in New England and may be, in part, a result of Virile Crayfish (s. l.) being introduced into the region. We also recovered an as yet undescribed species of Cambarincola from Rusty Crayfish in the West Aspetuck River, CT. As Rusty Crayfish supported the entocytherids T. riojai and A. sinuosa, both known from the North American Interior Plains (see above), it is likely that this new species also originates from this central region, and has co-invaded with its host. In our survey, we recovered only 5 of the 12 crayfish species previously reported from New England, which may limit our assessment of symbiont diversity region-wide. Of these 5 crayfishes, only Big Water Crayfish and Spiny Cheek Crayfish are thought to be native to the region. Virile Crayfish, Rusty Crayfish, and White River Crayfish were likely introduced by human activities. Notably, we did not collect Common Crayfish, probably due to a lack of focus on appropriate habitat. Quinebaug Crayfish, described in 2008, is separated from its sister taxon, Virile Crayfish, genetically and by a limited suite of morphological characters (i.e., curvature of the 1st pleopod and of the dactyl in form-I males; Mathews and Warren 2008, Mathews et al. 2008). Unfortunately, we were unable to consistently separate the 2 species, as the purported taxonomically informative morphological characters were highly variable, with no clear spatial pattern or concordance with molecular genetic data (B.W. Williams, unpubl. data). This finding indicates the Northeastern Naturalist Vol. 26, No. 1 L. Lukas, P.G. Weaver, and B.W. Williams 2019 165 need for a reevaluation of the characters used to delimit Quinebaug Crayfish, as an ability to distinguish this native species from its introduced congener, Virile Crayfish, is critical for effective conservation measures. We did collect White River Crayfish in southern New Hampshire; this is the first published record of this species from the state, and indicates that the species is spreading in New England, likely via human-mediated translocation. Though we did not recover any symbionts on White River Crayfish from this locality, or elsewhere in this study, Gelder et al. (2001) reported C. mesochoreus on White River Crayfish near the Atlantic coast, in Yarmouth, MA. Our study helps to fill previous distributional gaps of crayfish symbionts in New England, and establishes a baseline for future studies. It will be interesting to pursue changes in symbiont communities over time as native crayfish populations are overtaken by invasive species. This process may reduce the already low diversity of native crayfish symbionts via extirpation, yet, may also increase overall symbiont diversity by adding new species to the system. Acknowledgments We are grateful to Janet Edgerton for bibliographic assistance and Dr. Stuart R. Gelder for aid in confirming branchiobdellidan identifications. Crayfish recovered from Connecticut were collected under Scientific Collecting Permit SC-16017 in 2016 and Wildlife Resources Permit 1718005 in 2018. Literature Cited Aiken, D.E. 1965. Distribution and ecology of three species of crayfish from New Hampshire. American Midland Naturalist 73(1):240–244. Beauchene, M. 2011. Crayfish distribution project. Connecticut Department of Energy and Environmental Protection Bureau of Water Protection and Land Reuse. 17 pp. Available online at http://www.ct.gov/deep/lib/deep/water/water_quality_management/monitoringpubs/ 2011_crayfishdist.pdf. Accessed 17 October 2017. Crocker, D.W. 1979. The crayfishes of New England. Proceedings of the Biological Society of Washington 92(2):225-252. Dyke, A.S., and V.K. Prest. 1987. Late Wisconsinan and Holocene history of the Laurentide ice sheet. 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