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In this study the taxonomic status of three species of freshwater asellid isopod crustaceans, Lirceus hargeri, Lirceus usdagalun, and Lirceus culveri is evaluated using a large-scale RNA-seq data set. Whether each are distinct species, or whether they may be morphological variants of the same species is of particular importance for L. usdagalun, an endangered species, and L. culveri, a species of concern, since synonymy of the two could result in significantly reduced protections for the two taxa. RNA-seq was conducted on pooled individuals from each of two populations of L. usdagalun and L. hargeri, and one population of L. culveri. A single transcriptome was assembled de novo from the reads from all five populations, blasted against the NCBI non-redundant protein database, and sequence analysis was conducted on ≥ 13,468 highly expressed transcripts with significant blastx hits (E

Large, pulsed sodium chloride (NaCl) additions can increase mortality of aquatic biota, but longer-term effects from low-level additions are less understood. Small ionic increases may alleviate sodium (Na) limitation or osmoregulatory stress, thereby increasing microbial respiration and macroinvertebrate consumption and growth. We manipulated NaCl levels in microcosms containing just sweetgum (Liquidambar styraciflua L.) leaves with associated microbes, or leaves, microbes, and one of two macroinvertebrate detritivores (Tipula abdominalis Say in Experiment I and Lirceus sp. in Experiment II). In Experiment I, microcosms had either ambient or elevated NaCl (3 or 7 mg Na l−1, respectively). Contrary to predictions, microbial respiration did not significantly differ between treatments after 4 weeks. However, after 2 weeks, T. abdominalis marginally decreased leaf consumption in elevated treatments without change in growth. Experiment II had three NaCl treatments: low (ambient), medium, and high (3, 14, and 140 mg Na l−1, respectively). After 6 weeks, microbial respiration averaged 15% lower in medium and 29% lower in high than in low treatments. Throughout, Lirceus sp. ate and grew similarly in low and medium treatments. However, Lirceus sp. growth was 12% slower in high than in low treatments. Lirceus sp. ate 74% more leaves in high than medium treatments, but growth and assimilation did not differ. Therefore, we infer possible osmoregulatory stress. Even low-level NaCl inputs may negatively impact some detritivores, which could alter stream processes.

L. dennisi Clamp, 1987 Museum Depositions. USNM. 40928 Holotype; 40929 Paratype. Habitat. Freshwater. Distribution. BR: Nearctic (May��n-Estrada & Aguilar-Aguilar 2012). Mexico: Michoac��n, P��tzcuaro Lake (19 �� 32��to 19 �� 41��N, 101 �� 32��to 101 �� 43��W). USA: Missouri, Jefferson Co., 4.3 km NNE Hillsboro, creek running parallel to MO 21 at Hayden Rd. (38 �� 16 ' 14.36 "N, 90 �� 33 ' 21.04 "W). North Carolina, Franklin Co., 10.4 km E Youngsville, Crooked Cr. at US 401 (36 ��0' 44.25 "N, 78 �� 21 '40.00"W). Virginia, Grayson Co., 5.1 km S Independence, creek tributary to New R. at US 21-221 bridge (36 �� 34 ' 34.63 "N, 81 �� 9 ' 27.31 "W). Hosts. Mexico: Cambarellus patzcuarensis Villalobos (exposed body surface). USA: Cambarus (Cambarus) bartonii bartonii (Fabricius, 1798), C. chasmodactylus James, Orconectes illinoiensis Brown (exposed body surface). References. Clamp 1987 a; Fernandez-Leborans & Tato-Porto 2000; May��n-Estrada & Aladro-Lubel 2000; Fernandez-Leborans 2009., Published as part of May��n-Estrada, Rosaura & Clamp, John C., 2016, An annotated checklist of species in the family Lagenophryidae (Ciliophora, Oligohymenophorea, Peritrichia), With a brief review of their taxonomy, morphology, and biogeography, pp. 451-492 in Zootaxa 4132 (4) on page 473, DOI: 10.11646/zootaxa.4132.4.1, http://zenodo.org/record/257628, {"references":["Mayen-Estrada, R. & Aguilar-Aguilar, R. (2012) Track analysis and geographic distribution of some Lagenophrys Stein, 1852 (Protozoa: Ciliophora: Peritrichia) species. Journal of Natural History, 46, 249 - 263. http: // dx. doi. org / 10.1080 / 00222933.2011.626531","Clamp, J. C. (1987 a) Five new species of Lagenophrys (Ciliophora, Peritricha, Lagenophryidae) from the United States with observations on their developmental stages. Journal of Protozoology, 34, 382 - 392. http: // dx. doi. org / 10.1111 / j. 1550 - 7408.1987. tb 03197. x","Fernandez-Leborans, G. & Tato-Porto, M. L. (2000) A review of the species of protozoan epibionts of crustaceans. Crustaceana, 73, 643 - 683. Avaliable from: http: // www. jstor. org / stable / 20106331 (Accessed 17 Jun. 2016)","Mayen-Estrada R. & Aladro-Lubel, M. A. (2000) First record of Lagenophrys dennisi (Ciliophora: Peritrichia) on the exoskeleton of crayfish Cambarellus patzcuarensis. Journal of Eukaryotic Microbiology, 47, 57 - 61. http: // dx. doi. org / 10.1111 / j. 1550 - 7408.2000. tb 00011. x","Fernandez-Leborans, G. (2009) A review of recently described epibioses of ciliate Protozoa on Crustacea. Crustaceana, 82, 167 - 189."]}

L. diogenes (Jankowski, 1986) Circolagenophrys diogenes Jankowski 1986: 81 -82. Lagenophrys incompta Clamp 1987: 385 -386. Museum Depositions. USNM. 40930 Holotype; 40931 Paratype. Habitat. Freshwater. Distribution. BR: Nearctic. USA: Pennsylvania (41 �� 11 ' 58.50 "N, 77 �� 11 ' 47.26 "W). Missouri, Jefferson Co. 4.3 km NNE Hillsboro, creek running parallel to MO 21 at Hayden Rd. (38 �� 16 ' 14.36 "N, 90 �� 33 ' 21.04 "W). Hosts. USA: Cambarus diogenes Girard (gills), Orconectes illinoiensis (gills and branchial chamber). References. Jankowski 1986; Clamp 1987 a; Fernandez-Leborans & Tato-Porto 2000; Fernandez-Leborans 2009., Published as part of May��n-Estrada, Rosaura & Clamp, John C., 2016, An annotated checklist of species in the family Lagenophryidae (Ciliophora, Oligohymenophorea, Peritrichia), With a brief review of their taxonomy, morphology, and biogeography, pp. 451-492 in Zootaxa 4132 (4) on page 473, DOI: 10.11646/zootaxa.4132.4.1, http://zenodo.org/record/257628, {"references":["Jankowski, A. W. (1986) New and little known genera of ciliated protozoa (Phylum Ciliophora). In: Krylov, M. V. (Ed.), Systematics of Protozoa and their phylogenetic links with lower Eukaryotes. Trudy Zoologicheskogo Instituta Akademii Nauk SSSR 144, pp. 72 - 88.","Clamp, J. C. (1987 a) Five new species of Lagenophrys (Ciliophora, Peritricha, Lagenophryidae) from the United States with observations on their developmental stages. Journal of Protozoology, 34, 382 - 392. http: // dx. doi. org / 10.1111 / j. 1550 - 7408.1987. tb 03197. x","Fernandez-Leborans, G. & Tato-Porto, M. L. (2000) A review of the species of protozoan epibionts of crustaceans. Crustaceana, 73, 643 - 683. Avaliable from: http: // www. jstor. org / stable / 20106331 (Accessed 17 Jun. 2016)","Fernandez-Leborans, G. (2009) A review of recently described epibioses of ciliate Protozoa on Crustacea. Crustaceana, 82, 167 - 189."]}

Lirceus brachyurus (Harger, 1876) (Fig. 6) Material examined. MARYLAND: Frederick Co., spring at Fountain Rock, 1 mile [1.6km] SW Walkersville, 26 February 1986, 30��; Washington Co.: Big Spring, DJF, 23 July 1988, 9��; Troupe Springs, DJF, 29 May 1988, 23; spring on SR 63, 2 miles [3.2km] north SR 40, AN, 15 October 1978, 25��. Range. These Maryland localities occur between those previously known in Virginia and Pennsylvania (Hubricht & Mackin 1949; Lewis 2009). Many other samples of L. brachyurus (many collected by Leslie Hubricht) are present in the NMNH, spanning an area from western North Carolina through Virginia and West Virginia to Pennsylvania. This species usually occurs in springs., Published as part of Lewis, Julian J., Bowman, Thomas E. & Feller, Daniel J., 2011, A synopsis of the subterranean asellids of Maryland, U. S. A., with description of Caecidotea alleghenyensis, new species (Crustacea: Isopoda: Asellota), pp. 54-64 in Zootaxa 2769 on page 63, DOI: 10.5281/zenodo.207750, {"references":["Harger, O. (1876) Description of Mancasellus brachyurus, a new fresh-water Isopod. American Journal of Science and Arts, 6, 304 - 305.","Hubricht, L. & Mackin, J. G. (1949) The freshwater isopods of the genus Lirceus (Asellota, Asellidae). American Midland Naturalist, 42, 334 - 349.","Lewis, J. J. (2009) Three new species of Caecidotea, with a synopsis of the asellids of Virginia (Crustacea: Isopoda: Asellidae). Virginia Museum of Natural History Special Publication No. 16, 245 - 259."]}

In North America, crustaceans of the Order Isopoda include approximately 150 species inhabiting freshwaters distributed among four suborders. All members of the group share in common the dorsoventrally flattened appearance and seven pairs of legs. The dominant group is the Family Asellidae (Suborder Asellota) which contains eight genera, including Caecidotea with 81 species and Lirceus with 15 species. In the eastern United States, the asellids are ubiquitous in every kind of epigean aquatic habitat and a diverse assemblage of species also occurs in caves and other subterranean habitats. The isopods of the Suborder Flabellifera, including the families Cirolanidae and Sphaeromatidae, have specialized to inhabit caves and hot springs, almost exclusively in the southwestern United States and Mexico. Likewise, anthurid and microcerberid isopods are known collectively from three rare groundwater species. None of the freshwater isopods in North America have any significant economic importance. Due to the high degree of endemism of the fauna, significant conservation challenges are presented as habitats are encroached upon by man. Two species, the Socorro Isopod Thermosphaeroma thermophilum and Lee County Isopod Lirceus usdagalun, are listed in the United States as federal endangered species and the Madison Cave Isopod is listed as a threatened species.

The observation of pigmentation alteration in isopod crustaceans induced by acanthocephalans, known as pigmentation dystrophy, has been documented in North America in species of the aquatic genera Asellus Geoffroy, 1764, Lirceus Rafinesque-Schmaltz, 1820, and Caecidotea Packard, 1871, and in Europe, in Asellus. Recently, three depigmented specimens of Atlantoscia floridana (van Name, 1940), a terrestrial isopod, occurring from >Florida, USA to northern Argentina were found showing pigmentation dystrophy and harboring larval acanthocephalans. Photographic documentation of live and preserved, infected isopods is presented. Morphometric data and photomicrographs of the male, unencysted cystacanth specimen which allowed its placement in the genus Centrorhynchus Lühe, 1911 are presented. This is the first record of the phenomenon of pigmentation dystrophy in terrestrial isopod crustaceans, the first record of A. floridana infected by an acanthocephalan and the first record of a species of Centrorhynchus in a terrestrial isopod.

Nine species of asellid isopods are reported from groundwater habitats in Maryland. Three of these species are habitually found in springs: Lirceus brachyurus, Caecidotea kenki, and C. alleghenyensis, n. sp. The latter, described herein, is a member of the hobbsi group known only from the Allegheny Mountains in Garrett Co. Six species are obligate inhabitants of subterranean waters and are found primarily in Appalachian caves, although some have broad ranges that span noncavernous areas. The obligate subterranean species are Caecidotea pricei, C. franzi, C. holsingeri, C. mausi, C. vandeli and C. nordeni.

During the summer of 1974 an extensive survey of the shallow water (0-2 m) benthic fauna of the exposed Canadian shores of the Great Lakes was made. This report deals with the distribution of Amphipoda and Isopoda on various substrates in each lake. The amphipods were represented by Pontoporeia affinis, Hyalella azteca, Crangonyx gracilis, C. pseudogracilis, Gammarus fasciatus, G. lacustris and G. pseudolimnaeus. The isopod species were Asellus forbesi, A. intermedius, A. racovitzai and Lirceus lineatus. The distribution of each species is discussed and compared with previously published records.

The quantitative significance of bacterial biomass in the nutrition of detritivores remains equivocal. We have used tritiated thymidine to specifically label stable macromolecules in natural assemblages of sediment-associated and detritus-associated bacteria. This material was presented to the isopod (Lirceus sp.) and incorporation of bacterial biomass measured. The isopod incorporated roughly 1 ng bacterial carbon (mg wet wt.)-1 h-1 from leaf discs and about 6 ng mg-1 h-1 from sediment. Calculation of grazing rate from changes in cell counts yields grazing rates from 2.3–17.9 ng C mg-1 h-1. Even the maximum grazing rate, which is an overestimate of C assimilated, represents only 14.7% of C respired by the isopod.

During the unusual molt sequence of the fresh-water isopod,Lirceus brachyrus (Harger), the posterior half of the exoskeleton is shed 24 hours before the anterior half. At the half-molt stage, occurs in the posterior part while the anterior portion is in a pre-molt condition. The percentage difference in calcium in the two halves at half-molt and full-molt is22 (p

We examined patterns of habitat use of an isopod, Lirceus fontinalis, that coexists with predatory fish in second and third order permanent streams in central Kentucky, USA. Isopods were significantly more dense in Cladophora, a filamentous green alga, than on bare substrates of silt, sand, and gravel, and in submerged leaf litter when predatory fish were present. The dense, entangled filaments of the algae precluded most fish from entering Cladophora mats and eating isopods. Nonetheless, fish predation significantly reduced total isopod densities in these habitats. In laboratory manipulations, emergences from and entrances into Cladophora along with overall movements by isopods in open sandy areas were significantly reduced when green sunfish (Lepomis cyanellus) were present. Lirceus responded similarly to only water conditioned with green sunfish, indicating isopods use chemical cues, in part, to detect predatory fish. Isopods predominantly ate decaying leaf tissue (i.e., coarse particulate organic matter [CPOM] > 0.5 mm in diameter), but amounts of CPOM were significantly lower in Cladophora than in sediments of bare substrates. Lirceus did not eat the algae. Over 80% of the organic particulates in algal mats were < 0.5 mm (fine POM). Isopods reared on FPOM grew significantly slower than those on CPOM. Long-term use of algal mats poor in forage by isopods may adversely affect relative fitness since egg production by females is dependent on body size.

The isopods Asellus intermzedius, Lirceus garmani, and L. lineatus were studied to document further the occurrence of altered pigmentation in these hosts infected with species of Acanthocephalus. Specimens of A. intermedius from central Illinois, L. garmani from northwestern Arkansas, and L. lineatus from northwestern Ohio revealed differences in normal integumental pigmentation related to species, sex, reproductive state, and size. Integument of males and females of the three species was found to be more lightly pigmented when specimens harbored male, female, or multiple infections with acanthocephalans. Comparisons of light transmission through wholemounts of respiratory opercula of A. interinedius dem- onstrated that there was no significant difference in pigmentation among infection types. Regression analyses indicated (1) that the normnnal relationship between isopod length and pigmentation had been disrupted by acanthocephalan infections; (2) that a developmental relationship existed between isopod (length) and acanthocephalan (volume); (3) that there was not a direct relationship between acanthocephalan size and altered pigmentation, as might be expected for a gradual "depigmentation" process; and (4) that eye size was unaffected by parasitism. On the basis of these findings, the terminol- ogy, "pigmentation dystrophy," is proposed as more appropriate than the previously used terms, "non- pigmentation," 'depigmentation," and "color dichromatism."

Specimens of the 4 known species of Fessisentis, acquired through new collections in 6 states and laboratory infections, were compared with existing descriptions and collections. It was concluded that the number od longitudinal rows of proboscis hooks and lengths of proboscis receptacles, largest proboscis hooks, and reproductive systems are not useful in distinguishing the species. Egg size is of limited usefulness. Regardless of host or geographical locality, proboscis shape and length, the number of proboscis hooks in each longitudinal row, hook shape and size distribution, number of testes, number of cement glands, and female genital pore position are consistent differences. Cystacanths of Fessisentis fessus occurred in aquatic isopods, Asellus forbesi and Lirceus lineatus, in Jackson County, Illinois, where Siren intermedia is the usual definitive host. Laboratory infections confirmed the life cycle of this species.

Only small (4.0-5.0 mm) Asellus intermedius could be infected routinely with Acanthoceph- alus jacksoni in the laboratory. Acanthocephlus jacksoni required 90 days at 20 to 25 C to complete development. Thirty days after exposure to parasite eggs, infected isopods could be distinguished visually from uninfected, control isopods on the basis of altered pigmentation. Study of the development of normal integumental pigmentation of Lirceus garmani, L. lineatus, and As. intermedius showed that pigmentation becomes rapidly established during growth of isopods from approximately 2 to 5 mm in length. Suscep- tibility of isopods to infection at this critical time during ommochrome pigment production, and the (statistical) relationship of parasite growth to isopod growth during the 90 days of acanthocephalan de- velopment, support the hypothesis that North American species of Acanthocephalus interfere with the metabolic pathway for ommochrome pigmentation of isopod hosts.

The thermal tolerance of the aquatic isopod Lirceus brachyurus (Harger) was investigated. Survival, as measured by the time to 50% mortality (LT50), in- creased with increasing acclimation temperature. A tolerance polygon was constructed which defined the range of temperatures (0-23 C) tolerated by the isopods for 2 weeks. Upper lethal temperatures were lower than recorded for other isopod species. Lower lethal temperatures were related to those of other isopod species and to ice mineralization of creek water. The thermal tolerance of L. brachyurus did correspond to maximum and minimum water temperatures recorded in the study creek. The ecological significance with respect to the biology and habitat of L. brachyurus, and to power plant operation, is discussed.

In the genus Asellus we have, in the first and second pleopoda of the male, characters which can be relied upon to distinguish the species, but in Lirceus these appendages are so similar in different species that they are, with one exception, useless as a means of separation. This is not because the species of Lirceus are less distinct than Asellus, but requires that the animal as a whole be studied rather than a single appendage. To an experienced observer the various species are easily distinguished in the field by those subtile differences in form and color which are almost impossible to describe. Difficulties begin when one brings specimens into the laboratory and attempts to define the differences. The commonest cause of difficulty is depauperate specimens. Under adverse conditions the animals are stunted, the gnathopoda do not develop their processes, and the uropoda remain in juvenile form. When this depauperization is extreme the collection cannot be determined, but must be assumed to belong to the species in the range of which it was found.

The aquatic isopod, Lirceus fontinalis Rafinesque, occur- ring in granite gneiss weather pools on Mount Arabia, DeKalb Co., Ga., was investigated with respect to behavior patterns, interactions between the isopods and various environmental stresses, and determination of the major factors or combinations of factors that control the distribution and abundance of the isopods. Drought and high temperatures are the two major limiting factors controlling the Lirceus population. The capability of individuals to survive drought stress is reduced by acute exposure to, high tempera- tures. Klinokinetic responses to standing water and orthokinetic re- sponses to moisture contribute to the ability of individuals to survive drought stress by bringing about aggregations in or on top of moist sand under rocks. Rheotactic responses to rapidly flowing water account for repopulation of weather pools by bringing about emigrations from an intermittent creek to the pools, as confirmed by the movement of Zn-65-labeled isopods. High temperatures have an inhibiting effect on the rheotactic response. Isopods seldom venture from the dark recesses of rocks piled in weather pools because of a negative photokinetic response. Implications of a 43 factorial experiment on the interactions of gamma radiation, high temperature, and drought stresses are that introduction of ionizing gamma radiation into the habitat fod even brief periods at 16,400 R /hr would severely lower the ability of the population to withstand high temperatures and drought.