Anesthesia with Tricaine Methanesulfonate (MS222) and Propofol and Its Use for Computed Tomography of Red Swamp Crayfish (Procambarus clarkii).

Crayfish (Decapoda: Astacoidea and Parastacoidea) are among the few animals that have stem cells in hemolymph, with the capacity to continuously produce differentiated neuronal structures throughout life. As the use of crayfish and other invertebrates increases in biomedical research, we must develop laboratory standards and guidelines for performing clinical procedures. This manuscript presents introductory protocols for anesthesia in crayfish during diagnostic imaging. Five anesthetic protocols were evaluated: immersion in buffered tricaine methanesulfonate (MS222; 50 mg/L); immersion in buffered MS222 (150 mg/L); immersion in propofol (65 mg/L); injection of propofol (50 mg/kg); and injection of propofol (100 mg/kg) into the ventral surface of an abdominal somite. MS222 immersion (50 and 150 mg/L) had no observable effect on crayfish. After an extended period of time, immersion in propofol (65 mg/L) created a sedative effect suitable for short-term handling. Propofol injection (50 mg/kg) into the ventral surface of an abdominal somite created an effective plane of anesthesia without adverse effects during or after recovery. Propofol injection at 100 mg/kg had adverse effects and is not recommended for use in crayfish. CT imaging was performed successfully as proof of concept for handling anesthetized crayfish. These findings provide initial data for the anesthetization of crayfish used in research settings.

Integrative Taxonomy of Dermacentor variabilis (Ixodida: Ixodidae) with Description of a New Species, Dermacentor similis n. sp.

Dermacentor variabilis is the most widely distributed three-host tick in North America, and transmits a variety of pathogens. Within the United States, this species has a discontinuous distribution, widespread east of the Rocky Mountains and with a few populations west of the Rockies. Phylogenetic evidence based on individual markers or relatively small data sets has suggested that populations at both sides of this geographic barrier may correspond to two different species. In this study, we further explore this hypothesis using an integrative taxonomy framework. Both molecular (mitochondrial and nuclear markers) and morphological analyses of specimens collected from central-eastern and western states were performed to explore species delimitation in this taxon. Results from these analyses were consistent, and provide strong evidence that D. variabilis actually corresponds to two species. Herein, the western populations are described as a new species, Dermacentor similis n. sp. The usefulness of integrative taxonomy in the context of species delimitation is also discussed.

Two new species of burrowing crayfish in the genus Lacunicambarus (Decapoda: Cambaridae) from Alabama and Mississippi.

While sampling for the Rusty Gravedigger, Lacunicambarus miltus, Taylor et al. (2011) found one or more potentially undescribed burrowing crayfish species in the genus Lacunicambarus inhabiting the area between the Pascagoula River and Mobile Bay in southern Alabama and Mississippi. Molecular analyses by Glon et al. (2018) confirmed that samples from this area were genetically distinct from other Lacunicambarus crayfishes. These findings prompted a dedicated sampling trip in January 2020. We used morphological and molecular analyses to investigate the specimens we collected and, based on our results, we describe two new crayfish species: the Lonesome Gravedigger, L. mobilensis sp. nov. and the Banded Mudbug, L. freudensteini sp. nov. Lacunicambarus mobilensis sp. nov. is sister to the Rusty Gravedigger, L. miltus, while L. freudensteini sp. nov. is sister to the Painted Devil Crayfish, L. ludovicianus. Both new species are currently known from a small number of sites in southern Alabama and Mississippi and may require conservation attention. In addition, we provide an updated key to Lacunicambarus crayfishes that includes these new species.

Lacunicambarus dalyae: a new species of burrowing crayfish (Decapoda: Cambaridae) from the southeastern United States.

The Jewel Mudbug, Lacunicambarus dalyae sp. nov., is a large, colorful primary burrowing crayfish found in Alabama, Florida, Georgia, Mississippi and Tennessee. This species is most similar in appearance to the Paintedhand Mudbug, L. polychromatus, a species found across the Midwestern United States. The ranges of the two species overlap minimally, and they can be distinguished from each other based on several characters, the most notable of which is the much longer central projection of the gonopod in Form I and II males of L. dalyae sp. nov. relative to L. polychromatus. Like its congeners, L. dalyae sp. nov. is commonly found in burrows in the banks and floodplains of streams and is resilient to a moderate amount of anthropogenic habitat degradation, being occasionally collected from burrows in roadside ditches and urban lawns.

Lacunicambarus chimera: a new species of burrowing crayfish (Decapoda: Cambaridae) from Illinois, Indiana, Kentucky, and Tennessee.

Lacunicambarus diogenes (Girard 1852) was, until recently, considered to be one of the most widely distributed North American crayfish species, occurring in 31 U.S. States and one Canadian province east of the North American Rocky Mountains. Glon et al. (2018) investigated this claim and found that L. diogenes sensu lato was actually a species complex. The authors redescribed L. diogenes and restricted its range to the Atlantic Coastal Plain and Piedmont ecoregions of eastern North America. In doing so, they also revealed the existence of several probable undescribed species of Lacunicambarus that were previously considered to be L. diogenes. Here, we use morphological and molecular techniques to distinguish and describe one of these species: Lacunicambarus chimera sp. nov., a large primary burrowing crayfish found in parts of the Lower Mississippi, Ohio, Tennessee and Upper Mississippi River Basins. Lacunicambarus chimera is morphologically similar to L. diogenes, from which it can be distinguished by the greater number of spines on the ventrolateral margin of its merus, its wider antennal scale terminating in a short spine, and the presence of a single longitudinal stripe on the dorsal side of its abdomen. We also provide an updated key to Lacunicambarus.

Connecting laboratory behavior to field function through stable isotope analysis.

Inherent difficulties of tracking and observing organisms in the field often leave researchers with no choice but to conduct behavioral experiments under laboratory settings. However, results of laboratory experiments do not always translate accurately to natural conditions. A fundamental challenge in ecology is therefore to scale up from small area and short-duration laboratory experiments to large areas and long durations over which ecological processes generally operate. In this study, we propose that stable isotope analysis may be a tool that can link laboratory behavioral observations to past field interactions or function of individual organisms. We conducted laboratory behavioral assays to measure dominance of invasive rusty crayfish, Orconectes rusticus, and used stable isotope analysis to hindcast trophic positions of these crayfish under preceding natural conditions. We hypothesized that more dominant crayfish in our assays would have higher trophic positions if dominance were related to competitive ability or willingness to pursue high-risk, high-reward prey. We did not find a relationship between crayfish dominance and trophic position, and therefore infer that laboratory dominance of crayfish may not necessarily relate to their ecology in the field. However, this is to our knowledge the first attempt to directly relate laboratory behavior to field performance via stable isotope analysis. We encourage future studies to continue to explore a possible link between laboratory and field behavior via stable isotope analysis, and propose several avenues to do so.