Guenter A. Schuster

A Reassessment of the Conservation Status of Crayfishes of the United States and Canada after 10+ Years of Increased Awareness

Abstract The American Fisheries Society Endangered Species Committee herein provides a list of all crayfishes (families Astacidae and Cambaridae) in the United States and Canada that includes common names; state and provincial distributions; a comprehensive review of the conservation status of all taxa; and references on biology, conservation, and distribution. The list includes 363 native crayfishes, of which 2 (⟨ 1%) taxa are listed as Endangered, Possibly Extinct, 66 (18.2%) are Endangered, 52 (14.3%) are Threatened, 54 (14–9%) are Vulnerable, and 189 (52.1%) are Currently Stable. Limited natural range continues to be the primary factor responsible for the noted imperilment of crayfishes; other threats include the introduction of nonindigenous crayfishes and habitat alteration. While progress has been made in recognizing the plight of crayfishes, much work is still needed.

An annotated checklist and preliminary designation of drainage distributions of the crayfishes of Alabama

Abstract As a first step toward elucidating the current status of Alabamas crayfish fauna, museums known to have significant crayfish collections were queried for their holdings from that state. A total of 4649 records of Alabama crayfishes were obtained from seven museums. Three-hundred thirty of the records did not have suitable information for geo-referencing. The largest holdings were in the National Museum of Natural History (2544 records). Specimen identifications were verified, and all records were geo-referenced. Geographic distribution strongly favored upland drainages in the northern and central portions of the state. The Tennessee River drainage was the most collected drainage (1018 records, 23.6% of records). A total of 85 species of crayfishes are reported for the state of Alabama; only Orconectes virilis (Virile Crayfish) is deemed to be non-native. Even with the extensive collection of crayfish records in museums, there is a need for crayfish inventory work in Alabama. A total of 3107 records (76.3%) were collected prior to 1987, and 1379 (33.8%) were collected prior to 1970. In addition, there is a paucity of records from the coastal drainages of SE Alabama. There is also an under-representation of burrowing crayfishes, especially those classified as either primary or secondary burrowers. Only 212 (4.9%) of all records are of burrowing species. Lastly, a limited amount of fieldwork in Alabama has documented the presence of a species previously unreported for the state.

Monotypic no more, a description of a new crayfish of the genus Barbicambarus Hobbs, 1969 (Decapoda: Cambaridae) from the Tennessee River drainage using morphology and molecules

Abstract Recent fieldwork in the Shoal Creek drainage of the Tennessee River drainage in Tennessee has uncovered the presence of a new species of crayfish in the formerly monotypic genus Barbicambarus. The new species differs from the type species in possessing a median carina, less dense setae on the antennae, a less angular central projection, a spine at the dorsodistal margin of the merus of the cheliped, and a high level of divergence in the COI gene region. Collecting efforts have so far found the new taxon at only two locations and it is thought to be rare.

SYSTEMATICS AND BIOGEOGRAPHY OF ORCONECTES, SUBGENUS TRISELLESCENS, IN THE SOUTHEASTERN UNITED STATES, A TEST OF MORPHOLOGY-BASED CLASSIFICATION

Diagnosable taxonomic units are fundamental to conservation biology and management of resources and the need for sound science in both fields is more pressing for aquatic ecosystems. Within freshwater crayfishes, the North American genus Orconectes is one of the most diverse in the World. Accurate assessments of species level relationships and species boundaries within the genus have historically been hampered by a low number of variable morphological characters and inadequate sampling from across the ranges of many taxa. We examine a diverse group of southeastern United States stream dwelling Orconectes in the subgenus Trisellescens using 16S, COI mtDNA, and morphology to resolve uncertainties in species boundaries. Our results suggest that strong divergences exist between taxa found above and below the Fall Line in parts of the southeastern United States and the taxonomy for taxa found in that region should remain unchanged. However, using both molecular and morphological datasets we are unable to determine species limits for some taxa found on and below the Fall Line. Analysis of DNA data suggests that historical and ongoing genetic events such as gene introgression may contribute to these uncertainties. For taxa found on and below the Fall Line, we suggest tentative, taxonomic assignments. Finally, we argue for increased sampling of independent molecular datasets and increased sample sizes for all cambarid crayfish biogeographic studies.

Distribution and Conservation Status of the Rusty Gravedigger, Cambarus miltus, a Poorly Known Gulf Coastal Crayfish

Abstract Cambarus (Lacunicambarus) miltus (Rusty Gravedigger Crayfish) is a primary burrowing crayfish known from a limited portion of the Gulf Coastal region of the United States. The lack of form I males in collections has in the past prevented species-level identifications and hampered conservation reviews. We conducted an intensive status survey for C. miltus during 2007 and 2008. Our results suggest that the species is much more widespread than previously known and that conservation attention is unwarranted. Preferred habitat for the species is ephemerally flooded and thinly wooded floodplains of small streams and swamps.

Cambarus ( Depressicambarus ) clairitae , a new species of crayfish (Decapoda: Cambaridae) from Alabama with a review of the halli Group in the subgenus Depressicambarus

Cambarus (Depressicambarus) clairitae, new species, is an epigean crayfish from two drainages of the Locust Fork system in Blount and Jefferson counties, Alabama. It belongs to the halli Group in the subgenus Depressicambarus. The new species is morphologically most similar to Cambarus (Depressicambarus) englishi. They differ in a several morphological characters. Cambarus englishi has a more strongly recurved central projection, a wider areola, and a more distinct and set off rostral acumen than the new species. It also has light gray to white antennae while the antennae of the new species are brown. In addition to the description of the new species, the halli Group in Alabama is discussed.

Conservation Assessment and Habitat Notes for Three Rare Alabama Crayfishes: Cambarus cracens, Cambarus scotti, and Cambarus unestami

Abstract Over seventy percent of the worlds freshwater crayfish species are found within the United States, and much of this diversity is concentrated in the southeastern United States. Yet many of these species remain understudied. Of particular interest is the conservation status of these understudied taxa. We conducted fieldwork in 2011 across northeastern Alabama and northwestern Georgia to review the occurrence, habitat, and in some cases, local population densities of three crayfish species (Cambarus scotti, C. unestami, and C. cracens) to determine current distributions in relation to historical surveys. All three species occur in flowing small to medium-sized streams with firm substrates of gravel, cobble, and bedrock. Two species (C. scotti and C. unestami) have stable populations, occurring at 79% and 90%) of sites surveyed, respectively. In contrast, surveys for the third crayfish species (C. cracens) indicated a need for conservation action, with this species occurring at a single site.

A new dwarf crayfish (Decapoda: Cambaridae) from floodplain swamps in central Alabama

Cambarellus (Pandicambarus) rotatus, new species, is a dwarf crayfish from floodplain swamps in the Tombigbee and Black Warrior river drainages of Greene, Hale, and Marengo counties, Alabama. The new species is morphologically most similar to Cambarellus (Pandicambarus) lesliei. They differ in a several morphological characters. Cambarellus rotatus, new species, has gonopods that are rotated mesially so that the terminal elements oppose each other, and they have a short C-shaped sperm groove. These are unique features among known species of Cambarellus.

A new species of crayfish in the genus Orconectes (Decapoda: Cambaridae) from the Tennessee River Drainage with comments on and key to members of the O. juvenilis Species Complex

The crayfish subgenus Procericambarus (genus Orconectes) found in the Eastern Highlands of the United States represents a rich assemblage of stream-dwelling macroinvertebrates. While the taxonomic status and distribution of its members were clarified in a previous study, newly diagnosed characters and newly collected specimens warranted a revision to previous hypotheses of Procericambarus membership in the southeastern United States. Using morphological characters, we describe herein a new species of crayfish occurring in the Tennessee River drainage of northern Alabama and southwestern Tennessee. We also provide a revised key for the identification of members of O. juvenilis Species Complex.

The Sipsey River, Alabama: A Crayfish Diversity “Hotspot”?

Abstract The southeastern United States contains ca. 250 species of crayfish. Of these, 85 are historically known from Alabama. Previous studies have shown that the Sipsey River drainage in western Alabama is a diversity “hotspot” for freshwater mussels (42 spp.) and fishes (102 spp.). This is attributed to diverse geologic features, an intact floodplain, lack of impoundments, and lack of urban centers. Intensive sampling of the Sipsey River drainage over a 2-year period resulted in a collection of 294 crayfish representing 12 species. Three of these species, Cambarus ludovicianus, Orconectes chickasawae, and Procambarus vioscai paynei are of conservation concern. Our results indicate that the Sipsey River harbors a greater richness of crayfish species per area than other drainages surveyed to date in Alabama.