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The ability to detect predators at a distance through chemical cues is often essential for prey, but spatial variation in predator presence and species may promote variability in the reactions of prey subpopulations. We collected isopods (Caecidotea communis) from three ponds: two with fish (sunfish in one, shiners in the other), and one without. We exposed individuals from these three subpopulations to kairomones and diet cues released by sunfish (Lepomis spp.) or golden shiners (Notemigonus crysoleucas). We used time-lapse photography to calculate the rate of movement and proportion of time isopods spent moving, both soon after cue introduction and twenty-five minutes later. Thus, we tested for reactions to cues, for rapid cue degradation or short-term habituation, and for effects of natal pond. The isopods from all subpopulations did not alter their rate of movement nor their percent of time moving when exposed to dechlorinated tap water or cues from sunfish. The isopods from the pond containing shiners significantly increased their proportion of time moving, and showed a not significant tendency to move more rapidly, when exposed to cues from shiners as opposed to dechlorinated tap water. Our results are the first to demonstrate that isopods may lack a behavioral response to chemicals indicating likely imminent danger from the same species of fish as occur in their natal pond.

Caecidotea burkensis, a new species of subterranean asellid isopod, is described and illustrated from material collected from Lawson Cave, in Burke’s Garden, Tazewell County, Virginia. The type-locality in Burke’s Garden is located within the highest mountain basin in the southern Appalachians. Burke’s Garden is a unique, geologically isolated area encompassing one of the headwater streams of the New River basin. Phylogenetically, the isopod is a member of the forbesi Group, a clade comprised primarily of epigean species. The complex mountain valleys and coves of southwestern Virginia are an area of intense speciation among asellids that have produced a bizarre array of cavernicolous species belonging to groups of otherwise epigean isopods. In addition to a few subterranean species of the Caecidotea cannula and stygia Groups, the Lirceus hargeri Group possesses over a dozen species endemic to caves and springs in the region, mostly only now in the process of being discovered and described. With so much species richness, syntopy of two, or even three, asellid species is commonplace in caves and springs in southwestern Virginia.

Caecidotea chicoensis sp. nov. (Figs 10–13) Material examined: Holotype, male (CNCR 35516), length 9.5 mm, National Park Mineral del Chico, spring behind the visitor center, 20°11’01”N, 98°42’57”W, elev. 2985 m, Municipality Mineral del Chico, Hidalgo, Mexico, 12 December 2018, coll. L. García-Vázquez and M. C. Jordán-Hernández. Paratypes, male (CNCR 35517) length 9.5 mm; same data of collection and collectors as holotype; dissected parts pereiopod I, pereiopod IV, pleopod II; dissected structures for right pleopod drawings I, III, IV and V in the specimen tube. Females present in the same container. Diagnosis. Male body 3 times its width. Head rectangular, width 2.7 length, anterior margin concave; eyes small, oblique oval, length 1.5 width, postmandibular lobes produced. Pleotelson lateral margins parallel, caudomedial lobe subacute produced. Pleopod II protopod ventral surface with cuticular scales on dorsal edge; exopod with ornamentation on ventral surface; endopod medial surface with elongated transverse striations. Uropods irregular, lanceolate. Description. Male (CNCR 35516) 9.5 mm (Fig. 10A); head rectangular, width 2.7 times length, anterior margin concave. Eyes present, oval, dark pigmented, length 0.4 width. Postmandibular lobes produced. Subrectangular pereionites lateral margins straight with setae, as well as on dorsal surface. Pereionite 1 length 1.0 pereionite 2 length; pereionite 1 0.9 pereionite 3 length; pereionites 6–7 with subrectangular margins, posterior narrowing. Antennula flagellum with 11 articles, reaching distal antenna podomere middle, when projecting forward; last four segments with aestetascs in formula 0–1–1–1. Antenna flagellum with 67 articles; proximal article longer than wide, following articles decreasing in length. Pereiopod I (Figs 10B, 11A–B) propodus slender triangular, dactylus outer edge with simple setae as long as palm, irregular inner edge; inner and outer palmar margin with row simple setae; proximal process with 3 robust setae; mesial process acute, exceeding dactylus width. Pereiopods II–III (Fig. 10C – D) similar length. Pereiopod IV (Figs 10E, 11C), propodus with spine in dactylus; dactylus robust; dactylus length 0.5 propodus length, lower margin with five strong spines. Pereiopod V (Fig. 10F), basis similar length to propodus. Pereiopod VI (Fig. 10G) as long as pereiopod VII, basis length similar to carpus length. Pereiopod VII (Fig. 10H) 1.2 body length. Pleopod I (Fig. 12A) as long as pleopod II; protopod subrectangular, proximal margin rounded, length 1.6 width, inner margin with 3 retinacula, distal segment subrectangular, outer margin concave, length 2.6 times width, margins with 10 simple setae. Pleopod II (Fig. 13A–F), protopod subrectangular, distal edge with cuticular scales; exopod base triangular with distal spines; exopod oval, with small cuticular scales, distal margin with 20–25 long plumose setae; slender endopod, as length 4.6 width, 1.1 exopod length 0.8 times protopod length, mesial surface curved, with irregular reticulations, internal and external process prominent; endopod apex with 3 processes: cannula subcylindrical, apex truncated with transverse striations on mesial surface, caudal process present; mesial process subtriangular, striated surface; caudal process robust, subconical, rounded apex, armed with 2–6 cuticular scales directed proximally. Pleopod III (Fig. 12B), exopod oval with distal margin setose, length 1.4 endopod length, width 1.6 endopod width, transverse suture in proximal half, 20 plumose setae on distal margin, external margin with 40 simple setae; endopod short oval, 0.7 exopod length. Pleopod IV (Fig. 12C), exopod length 1.6 width, external margin with 10 proximal setae; endopod length 0.9 exopod length. Pleopod V (Fig. 12D), exopod oval, length 1.9 width, transverse suture not evident; endopod length 0.9, width 0.9 exopod length. Pleotelson (Fig. 12E), as wide as long, lateral margins parallel, rounded with several simple setae, caudomedial lobe produced subacute. Uropods (Fig. 12E), subsquare, length 0.9 pleotelson width, armed with robust setae; endopod irregular, lanceolate, length 1.1 pleotelson length, exopod as long as protopod. Habitat. The specimens of Caecidotea chicoensis sp. nov. were located in a small spring, approximately 1 meter in diameter, located behind the visitor center of Mineral del Chico National Park. The water that emerges from the spring runs through a small channel approximately 50 cm wide; algae growths and anuran larvae were also found. Distribution. Only known from the type locality. Etymology. This species is named after the Mineral del Chico National Park. Remarks. Caecidotea chicoensis sp. nov. can be distinguished from other Mexican species of Caecidotea by the presence of elongated striations on the medial surface of pleopod II endopod., Published as part of García-Vázquez, Leonardo, Pedraza-Lara, Carlos & Rodríguez-Almaraz, Gabino, 2021, Six new epigean species of Caecidotea (Isopoda: Asellidae) distributed along the Trans-Mexican Volcanic Belt in Central Mexico, pp. 45-77 in Zootaxa 4965 (1) on pages 56-61, DOI: 10.11646/zootaxa.4965.1.2, http://zenodo.org/record/4723078

Caecidotea mintzita sp. nov. (Figs 14–17) Material examined: Holotype, male (CNCR 35510), length 7.6 mm, Channel that flows next to the Mintzita spring, 19°38’53.74”N, 101°16’15.53”W, elev. 1892 m, Municipality La Mintzita, Michoacan, Mexico, 20 March 2018, coll. L. García-Vázquez and C. Pedraza-Lara. Paratypes, male (CNCR 35511), length 7.0 mm; same data of collection and collectors as holotype; dissected parts pereiopod I, pereiopod IV, pleopod II; dissected structures for right pleopod drawings I, III, IV and V in the specimen tube. Females present in the same container. Diagnosis. Male body length 3.7 times width; postmandibular lobes not produced; antennula flagellum exceeds last antennal segment, with pectinate setae in each article; antenna flagellum reaches anterior edge pereionite 6; antenna flagellum with 73 articles. Uropods 1.2 times pleotelson length. Description. Male (CNCR 35511) 7.6 mm (Fig. 14A); head width 1.6 length, anterior margin concave. Eyes present, oval, dark pigmented, length 0.5 times longer than wide. Postmandibular lobes not produced. Subrectangular pereionites ornamented with lateral setae. Pereionite 1 length 1.0 pereionite 2 length; pereionite 1 1.1 pereionite 3 length; pereionites 6–7 with subrectangular margins, widening posterior. Antennula flagellum with 11 articles, reaching distal edge antenna podomere; last four segments with aestetascs in formula 1–1–1–1. Antenna flagellum with 73 articles with pectinate setae in each article; proximal article longer than wide; last 15 elongated. Pereiopod I (Figs 14B, 15A–B) dactylus as long as palm, with simple setae; inner and outer palmar margin with row simple setae; proximal process with 3 robust setae; mesial process acute exceeding dactylus, distal process subacute; 0.5 mesial process length. Pereiopods II–III (Fig. 14C–D) similar length. Pereiopod IV (Figs 14E, 15C) propodus with spine in dactylus, robust 0.6 times dactylus width, dactylus length 0.6 propodus length, dactylus with row 3 strong spines. Pereiopod V (Fig. 14F) basis length 1.2 propodus length. Pereiopod VI (Fig. 14G) similar length to pereiopod VII, basis length 1.2 propodus length. Pereiopod VII (Fig. 14H) 0.6 body length. Pleopod I (Fig. 16A) length 1.1 pleopod II length; protopod subrectangular, proximal margin rounded, length 1.5 width, inner margin with 4 retinacula, subrectangular distal segment, outer margin curved, length 2.0 width, margins with 21 simple setae. Pleopod II (Fig. 17A–F), protopod subrectangular, proximal edge rounded, distal border with cuticular scales; exopod base with 2 spines in right upper corner; exopod oval with cuticular scales, distal margin with 20–22 plumose setae; slender endopod, mesial curved, length 3.9 width, exopod length 0.7 protopod length, internal and external process prominent, endopod apex with 3 processes: cannula conical, similar to a rolled blade; mesial process evident; caudal process robust, subconical, with rounded apex, armed on subapical dorsal surface with 4–18 cuticular scales. Pleopod III (Fig. 16B), exopod oval with distal margin setose, length 1.1 endopod length, width 1.6 endopod width, transverse suture in proximal half, distal margin with 12 plumose setae, external margin with 34 simple setae; endopod short oval, 0.8 exopod length. Pleopod IV (Fig. 16C), length 1.6 width, outer margin exopod with 6 proximal setae, endopod length 0.9 exopod length. Pleopod V (Fig. 17D), exopod oval, as long as 1.9 width; transverse suture not evident; outer margin with 5 proximal setae, endopod as long 0.9 as wide exopod. Pleotelson (Fig. 17E), subsquare, width1.0 length, lateral margins curved, with several simple setae, caudomedial lobe subacute produced. Uropods (Fig. 17E), 1.2 pleotelson length, armed with robust marginal setae; endopod length 1.3 exopod length; exopod as long as protopod. Habitat. The specimens of Caecidotea mintzita sp. nov. were collected in a channel that flows next to La Mintzita spring, 60 cm wide and 40 cm deep, just below of submerged rocks and at the roots of the riparian vegetation. Distribution. Only known from the type locality. Etymology. This species is named after the Mintzita spring. Remarks. Caecidotea mintzita sp. nov. is similar morphologically to the species C. xochimilca Rocha-Ramírez & Peñaloza-Daniel, 2011. The former species can be differentiated by the endopod apex cuticular scales conformation, which is 4–18 while in C. xochimilca 3–10 cuticular scales. The endopod length is 1.1 protopod length in C. xochimilca while in Caecidotea mintzita sp. nov. the endopod length 1.3 exopod length., Published as part of García-Vázquez, Leonardo, Pedraza-Lara, Carlos & Rodríguez-Almaraz, Gabino, 2021, Six new epigean species of Caecidotea (Isopoda: Asellidae) distributed along the Trans-Mexican Volcanic Belt in Central Mexico, pp. 45-77 in Zootaxa 4965 (1) on pages 61-64, DOI: 10.11646/zootaxa.4965.1.2, http://zenodo.org/record/4723078

Caecidotea alvarezi sp. nov. (Figs 2–5) Material examined: Holotype, male (CNCR 35519), length 5.0 mm, shore of the Chapala Lagoon, Jamay, 20°17’07.00”N, 102°42’36.97”W, elev. 1524 m, Municipality of Jamay, Jalisco, Mexico, 19 March 2018, coll. L. García-Vázquez and C. Pedraza-Lara. Paratypes, male (CNCR 35520), length 4.7 mm; same data of collection and collectors as holotype; dissected parts pereiopod I, pereiopod IV, pleopod II; dissected structures for right pleopod drawings I, III, IV and V in the specimen tube. Females present in the same container. Diagnosis. Male body 2.8 times longer than wide. Head trapezoidal, width 0.6 length, anterior margin straight; eyes 3 times longer than wide, postmandibular lobes not produced. Pleotelson lateral margins parallel, caudomedial lobe produced, broad, rounded. Pleopod II exopod with cuticular scales directed distally, as long as those in medial margin cannula; endopod with flagella, mesial process almost high as cannula. Uropods long as pleotelson length. Description. Male (CNCR 35519) 5.0 mm (Fig. 2); head width 2.8 length, anterior margin straight. Eyes present, oval, dark pigmented, length 0.6 width. Postmandibular lobes not produced. Subrectangular pereionites lateral margins ornamented with setae, pereionites 1–2 rounded, pereionites 3–5 straight, pereonites 6–7 rounded, posterior angle produced. Pereionite 1 length 1.1 pereionite 2 length; pereonite 1 0.9 pereionite 3 length; pereionites 6–7 wider, widening in posterior angle. Antennula flagellum with 10 articles, longer than distal antenna podomere middle; last four segments with aestethascs in formula 1–1–1–0. Antenna flagellum with 50 articles; proximal article wider than long; following articles decreasing in length. Pereiopod I (Figs 2B, 3A–B) propodus slender, dactylus longer than palm with five simple setae on outer surface, irregular inner edge; palmar margin with row simple setae; proximal process with robust spine length 0.3 mesial process length; mesial process acute, exceeding dactylus width. Pereiopods II–III (Fig. 2C–D) similar length. Pereiopod IV (Figs 2E, 3C–D), propodus with spine in dactylus; dactylus length 0.5 propodus length with 3 spines on lower margin. Pereiopod V (Fig. 2F) basis 1.3 propodus length. Pereiopod VI (Fig. 2G) similar length to pereiopod VII length, basis length 1.4 propodus length. Pereiopod VII (Fig. 2H) 0.5 body length. Pleopod I (Fig. 4A) length 1.1 pleopod II length; protopod trapezoidal, proximal margin straight, length 1.5 width, inner margin with 5 retinacula, distal segment subrectangular, outer margin concave, length 2.3 width, margins with 20 simple setae. Pleopod II (Fig. 5A–F), protopod subrectangular, proximal edge rounded; exopod oval, in dorsal view with two vertical rows cuticular scales adjacent to inner margin, distal margin with 20 short plumose setae; slender endopod, as long as 3.8 width, similar to exopod 0.7 protopod length, curved mesial surface with flagella, internal and external process prominent, with suture close to base; endopod apex with 3 processes: cannula short, shaped as ribbed blade, not closed, tip truncated rounded, almost reaching apex caudal process, ventral groove present, extending proximally from base to cannula more than 3.0 its length; mesial process evident, with transverse grooves on surface; caudal process robust, conical, rounded apex, armed on subapical dorsal surface with 7–17 cuticular scales directed proximally. Pleopod III (Fig. 4B), exopod oval with distal margin setose, length 1.1 endopod length, width 1.6 endopod width, transverse suture in proximal half, 15 plumose setae on distal margin, external margin with 6 simple setae; endopod short oval, 0.9 exopod length. Pleopod IV (Fig. 4C), exopod as long as 1.7 width, with pronounced notch, on outer margin, close to pleopod joint; endopod 0.9 exopod length. Pleopod V (Fig. 4D), exopod oval, as long as 1.8 width; transverse suture not obvious; endopod length 0.9 exopod length, width 0.7 exopod width. Pleotelson (Fig. 4E), subsquare, width 1.1 length, lateral margins parallel, with simple setae, caudomedial lobe broad rounded. Uropods (Fig. 4F), length equal to pleotelson length, armed with robust setae; length 0.5 endopod length; endopod linear, length 0.8 protopod length, exopod length 1.1 protopod length. Habitat. This species was collected on the shoreline of the Chapala lagoon within the roots of the water lily Eichornia crassipes, along with other crustaceans (e.g., crayfish of the genus Cambarellus and amphipods of the genus Hyalella). Distribution. Only known from the type locality. Etymology. This species is named in honor to Dr. Fernando Alvarez, curator of the National Crustacean Collection, in recognition to his career in the study of Mexican crustaceans. Remarks. C. alvarezi sp. nov. is similar to the species C. williamsi Escobar-Briones & Alcocer, 2002 from Laguna de Alchichica, Puebla. The two species, however, can be distinguished by the number of retinacula in pleopod I (3 in C. williamsi and 5 in C. alvarezi sp. nov.) and the shape of pereiopod I. C. williamsi has only mesial process, while C. alvarezi sp. nov. has both mesial and proximal processes., Published as part of García-Vázquez, Leonardo, Pedraza-Lara, Carlos & Rodríguez-Almaraz, Gabino, 2021, Six new epigean species of Caecidotea (Isopoda: Asellidae) distributed along the Trans-Mexican Volcanic Belt in Central Mexico, pp. 45-77 in Zootaxa 4965 (1) on pages 48-50, DOI: 10.11646/zootaxa.4965.1.2, http://zenodo.org/record/4723078

Caecidotea zacapuensis sp. nov. (Figs 22–25) Material examined: Holotype, male (CNCR 35522), length 7.5 mm, Laguna de Zacapu, 19°49’37.00”N, 101°47’23.00”W, elev. 1993 m, Municipality Zacapu, Michoacan, Mexico, 20 March 2018, coll. L. García-Vázquez and C. Pedraza-Lara. Paratypes, male (CNCR 35523), length 7.6 mm; same data of collection and collectors as holotype; dissected parts left pereiopod I, left pereiopod IV, pleopod II; dissected structures for right pleopod drawings I, III, IV and V in the specimen tube. 20 Males and 15 females (CNCR 35524). Diagnosis. Male body length 3.4 width. Head trapezoidal, width 2.4 length, anterior margin concave; eyes length 3.8 width. Pleopod III with 36 plumose marginal setae. Exopod pleopod IV with proximal incomplete transverse suture. Uropods length 0.7 pleotelson length. Description. Male (CNCR 35522) 7.5 mm (Fig. 22A); head trapezoidal, width 2.4 length, anterior margin concave; eyes present, oval, dark pigmented, length 3.8 width. Postmandibular lobes not produced. Subrectangular pereionites lateral margins with simple setae, pereionites 1–5 straight, pereionites 6–7 rounded. Pereionite 1 length 1.2 pereionite 2 length; pereionite 1 1.1 pereionite 3 length; pereionites 6–7 with lateral margins rounded, widening posterior. Antennula flagellum with 10 articles, longer than distal antenna podomere middle; last four segments with aestetascs in formula 1–0–1–1. Antenna flagellum with 65 articles; proximal article width 1.2 length; following articles decreasing in length. Pereiopod I (Figs 22B, 23A – B) dactylus outer edge with 10 simple setae; dactylus longer than palm; palmar margin with row simple setae; proximal process with 3 robust spines; mesial process acute, as wide as dactylus; distal process small acute triangular. Pereiopods II–III (Fig. 22C–D) similar length. Pereiopod IV (Figs 22E, 23C) propodus with spine in dactylus, dactylus length 0.6 propodus length, dactylus with 4 slender spines on lower margin. Pereiopod V (Fig. 22F) basis length 1.2 propodus length. Pereiopod VI (Fig. 22G) similar length to pereiopod VII, basis length 1.3 propodus length. Pereiopod VII (Fig. 22H) length 0.6 body length. Pleopod I (Fig. 24A) length 2.2 pleopod III length; basal segment oval, proximal margin straight, length 1.4 width, inner margin with 6 retinacula, distal segment oval, external margin medially straight, length 1.9 width, margins with 20 simple setae. Pleopod II (Fig. 25A–F), protopod subrectangular, proximal edge rounded, internal margin with 2 simple spines; exopod oval with small cuticular scales on inner and outer margin, exopod margin with 22 plumose setae; endopod slender, curved mesial surface, length 3.2 width, length 0.9 exopod length, length 0.7 protopod length, internal and external processes prominent; endopod apex with 3 processes: cannula short subcylindrical surpassing caudal process, like a semi-rolled sheet; mesial process evident; caudal process robust, subconical, with rounded apex, armed on subapical dorsal surface with 2–17 cuticular scales. Pleopod III (Fig. 24B), exopod oval, length 1.5 width, width 1.6 endopod length, transverse suture in proximal half, 36 plumose setae in distal and proximal margins; endopod subrectangular, length 0.9 exopod length. Pleopod IV (Fig. 24C), exopod length 1.6 width, external proximal margin with incomplete transverse suture, close to pleopod joint; endopod length 0.8 exopod length. Pleopod V (Fig. 24D), exopod oval, length 1.8 width, transverse suture not evident; endopod length 0.9 exopod length, width 0.8 exopod width. Pleotelson (Fig. 24E), subsquare, length 1.0 width, lateral margins parallel, with simple marginal setae, caudomedial lobe produced subacute. Uropods (Fig. 24E), length 0.7 pleotelson length, armed with robust marginal setae, apical endopod setae, exopod length 1.2 endopod length; protopod length 1.1 exopod length. Habitat. This species was located on the shore of the Zacapu lake, between the roots of the aquatic vegetation, in the water lily Eichornia crassipes. Distribution. Known only from the type locality. Etymology. This species is named after the municipality Zacapu, where it inhabits. Remarks. The pleopod IV of Caecidotea zacapuensis sp. nov. is similar to the one of Caecidotea buzwilsoni sp. nov. from Yuriria Lagoon. Both can be differentiated using the transverse suture in pleopod IV: incomplete in Caecidotea zacapuensis sp. nov., and complete in Caecidotea buzwilsoni sp. nov., Published as part of García-Vázquez, Leonardo, Pedraza-Lara, Carlos & Rodríguez-Almaraz, Gabino, 2021, Six new epigean species of Caecidotea (Isopoda: Asellidae) distributed along the Trans-Mexican Volcanic Belt in Central Mexico, pp. 45-77 in Zootaxa 4965 (1) on pages 70-75, DOI: 10.11646/zootaxa.4965.1.2, http://zenodo.org/record/4723078

Caecidotea villalobosi sp. nov. (Figs 18–21) Material examined: Holotype, male (CNCR 35506), length 11 mm; Lago de Catemaco, Coyame, 18°26’12”N, 95°01’27”W, elev. 359 m, Municipality Catemaco, Veracruz, Mexico, 2 November 2017, coll. L. García-Vázquez and C. Pedraza-Lara. Paratypes, male (CNCR 35507), length 10.0 mm; same data of collection and collectors as holotype; dissected parts pereiopod I, pereiopod IV, pleopod II; dissected structures for right pleopod drawings I, III, IV and V in the specimen tube. 2 males and 3 females (CNCR 35508, CNCR 35509), Laguna Mahahual, 18°39’36”N, 95°18’30W, Municipality San Andrés Tuxtla, Veracruz, Mexico, coll. J. L. Villalobos, E. Moreno and I. Toledano. Diagnosis. Male body 3.2 times longer than wide. Head width 1.4 length, anterior margin concave, lateral margins straight; eyes width 2.1 length, postmandibular lobes not produced; Pereiopod I with dactylus inner edge serrated; dactylus pereiopod IV serrated. Description. Male (CNCR 35506) 11 mm (Fig. 18A); head trapezoidal, head width 1.4 length, anterior margin concave. Eyes present, oval, dark pigmented, width 2.1 length. Postmandibular lobes not produced. Subrectangular pereionites, lateral margins with setae. Pereionite 1 length 0.9 pereionite 2 length; pereionite 1 1.1 pereionite 3 length; pereionites 6–7 with oval margins; posterior widening. Antennula flagellum with 9 articles, longer than distal antenna podomere middle; last four segments with aestetascs with formula 1–0–1–0. Antenna flagellum with 57 articles with pectinate setae; proximal article longer than wide; following articles decreasing in length. Pereiopod I (Figs 18B, 19A–B) dactylus with robust seta on dactylus, inner edge serrated; proximal process with 3 robust setae; acute mesial process not exceeding dactylus width, bicuspid distal process. Pereiopods II– III (Figs 18C–D) similar length. Pereiopod IV (Figs 18E, 19C–D), propodus with robust finger-like projection in dactylus, dactylus length 0.9 propodus length, dactylus serrated. Pereiopod V (Fig. 18F) length basis 1.4 propodus length, dactylus curved hooked. Pereiopod VI (Fig. 18G) smaller than pereiopod VII, basis length 1.3 propodus length, dactylus with spine on lower margin. Pereiopod VII (Fig. 18H) length 0.4 body length. Pleopod I (Fig. 20A) length 1.1 pleopod II length; basal segment oval, proximal margin straight, length 1.3 width, internal margin with 3 retinacula, distal segment oval, outer margin curved in apical portion, length 1.8 width, margins with 12 simple setae. Pleopod II (Fig. 21A–F), protopod subsquare, inner proximal edge straight, with simple short distal seta, dorsal distal edge with cuticular scales; exopod base with spine on right distal border, exopod oval, with rows cuticular scales, distal margin with 15–19 long plumose setae; slender endopod, as long as 3.5 width, exopod length 0.7 protopod length; inner surface curved; internal and external processes prominent, apex with 3 terminal processes: caudal process rounded, cannula short subcylindrical, with a circular apex; mesial process present; endopod subapical portion armed with 14–16 cuticular scales. Pleopod III (Fig. 20B), exopod oval with distal margin setose, length 1.2 endopod length, width 1.9 endopod width, transverse suture in proximal half, 21 marginal plumose setae, external margin with 8 simple setae; endopod oval, 1.2 exopod length. Pleopod IV (Fig. 20C), exopod length 1.5 width, external margin with 4 proximal setae, endopod length 1.1 exopod length. Pleopod V (Fig. 20D), exopod oval, exopod length 1.9 width; external margin with 4 simple setae; transverse suture not evident; endopod notched on outer proximal edge, endopod width 1.2 exopod width. Pleotelson (Fig. 20E), subsquare, width 1.1 length, lateral margins parallel, with simple setae, caudomedial lobe produced subacute. Uropods (Fig. 20F), length 0.7 pleotelson length, armed with robust setae; endopod and exopod lanceolate, endopod length 1.0 exopod length, exopod length 1.1 protopod length. Habitat. The Caecidotea villalobosi sp. nov. specimens were collected on the shore of Catemaco Lake, below rocks submerged in water, as well as on the roots of the water lily Eichornia crassipes. It is important to mention that this species is not abundant in the region. Distribution. Known from the type locality and Laguna Mahahual, San Andrés Tuxtla, Veracruz. Etymology. This species is named after Dr. José Luis Villalobos Hiriart for being an exemplary mentor for the first author and for being an exceptional carcinologist, as well as his contributions to the knowledge of Mexican crustaceans. Remarks. Argano (1977) reported C. communis (Say, 1818) in the Catemaco lake in similar conditions where we collected Caecidotea villalobosi sp. nov., between the roots of a water lily and under submerged rocks on the shore of the lake. Argano mentioned that C. communis has a wide distribution in Mexico and also takes up Bowman’s (1975) hypothesis about an artificial introduction to Mexico due to human action. However, morphological comparisons with the species C. communis sensu Williams (1970), allow it to be clearly distinguished by the following characters: rounded head, anterior margin concave; pleotelson in C. communis is subcircular, as long as wide; caudomedial lobe obtuse produced; pleopod I wider and subrectangular, with 24 simple setae in distal margin, while Caecidotea villalobosi sp. nov. has 12 simple setae. The number of retinacula is 5 in C. communis while Caecidotea villalobosi sp. nov. has 3 retinacula; Regarding the apical elements of the pleopod II endopod, the cannula of C. communis is thin, simple, and elongated, surpassing the distal edge of the caudal process, which lacks cuticular scales. The cannula of Caecidotea villalobosi sp. nov. is short, subcylindrical, does not reach the distal edge of the caudal process and has cuticular scales., Published as part of García-Vázquez, Leonardo, Pedraza-Lara, Carlos & Rodríguez-Almaraz, Gabino, 2021, Six new epigean species of Caecidotea (Isopoda: Asellidae) distributed along the Trans-Mexican Volcanic Belt in Central Mexico, pp. 45-77 in Zootaxa 4965 (1) on pages 67-70, DOI: 10.11646/zootaxa.4965.1.2, http://zenodo.org/record/4723078, {"references":["Argano, R. (1977) Asellota del Messico meridionale e Guatemala (Crustacea, Isopoda). Accademia Nazionale dei Lincei, 171, 101 - 124.","Say, T. (1818) An account of the Crustacea of the United States, part 7. Journal of the Academy of Natural Sciences of Philadelphia, 1, 374 - 401.","Bowman, T. E. (1975) Three new troglobitic asellids from Western North America (Crustacea: Isopoda: Asellidae). International Journal of Speleology, 7, 339 - 356. https: // doi. org / 10.5038 / 1827 - 806 X. 7.4. 3","Williams, W. D. (1970) A revision of North American epigean species of Asellus (Crustacea: Isopoda). Smithsonian Contributions to Zoology, 49, 1 - 79. https: // doi. org / 10.5479 / si. 00810282.49"]}

Caecidotea buzwilsoni sp. nov. (Figs 6–9) Material examined: Holotype male (CNCR 35528), length 8.0 mm, Laguna de Yuriria, 20°13’11”N, 101°11’05”W, elev. 2275 m, Municipality Yuriria, Guanajuato, Mexico, 22 October 2019, coll. L. García-Vázquez and C. Pedraza-Lara. Paratypes, male (CNCR 35529), length 7.6 mm, same data of collection and collectors, as holotype; dissected parts pereiopod I, pereiopod IV, pleopod II; dissected structures for right pleopod drawings I, III, IV and V in the specimen tube. 15 Males and 10 females (CNCR 35530). Diagnosis. Male body length 3.2 width. Head trapezoidal, width 1.9 length, anterior margin straight; eyes large oval, length 2.0 width. Pleopod IV exopod suture transverse complete. Uropod endopod elongated, oval, length 2.2 width; exopod lanceolate, slender, length 2.7 width. Description. Male (CNCR 35528) 8.0 mm (Fig. 6A); head width 1.9 length, anterior margin concave. Eyes present, oval, dark pigmented, length 2.0 width. Postmandibular lobes not produced. Subrectangular pereionites, ornamented with marginal setae. Pereionite 1 length 1.2 pereionite 2 length; pereionites 6–7 wider, with diagonal margins, widening in posterior angle. Antennula flagellum with 11 articles, longer than distal antenna podomere middle; last four segments with aestetascs in formula 1–1–1–1. Antenna flagellum with 67 articles; proximal article wider than long; following articles increasing in length. Pereiopod I (Figs 6B, 7A), triangular propodus, dactylus curved, propodus palm longer than dactylus; palm with inner and outer edges, ornamented with simple setae; proximal process with 3 robust setae; mesial process acute, not exceeding dactylus width; distal process Subacute length 0.3 mesial process length. Pereiopods II–III (Figs 6C–D), with similar length. Pereiopod IV (Figs 6E, 7B–C), propodus with spine in dactylus; dactylus length 0.6 propodus length, with four spines on lower margin. Pereiopod V (Fig. 6F), basis length 1.3 propodus length. Pereiopod VI (Fig. 6G), similar length to pereiopod VII, basis length 1.2 propodus length. Pereiopod VII (Fig. 6H), length 0.7 body length. Pleopod I (Fig. 8A) length 2.3 pleopod III length; protopod oval, proximal margin straight; protopod 1.7 width, inner margin with 5 retinacula, distal segment subrectangular, outer margin medially straight, length 2.0 width, margins with 23 simple setae. Pleopod II (Fig. 9A–F), protopod subsquare, proximal edge rounded; in dorsal view, exopod base with one distal spine on inner edge, exopod oval with small cuticular scales directed distally on inner dorsal margin, exopod distal margin with 21 plumose setae; slender endopod, with pubescent surface, mesial portion curved, length 3.5 width, similar length to exopod 0.6 protopod length, internal and external process prominent, external with suture close to base, endopod apex with 3 processes: cannula conical, short, with truncated apex lower than caudal process, extending proximally from cannula more than 3.0 its length; mesial process evident; caudal process robust, conical, rounded apex, armed on subapical dorsal surface with 1–17 cuticular scales directed proximally; cuticular scales with pubescence, similar to short villi. Pleopod III (Fig. 8B), exopod oval with distal margin setose, length 1.2 endopod length, width 1.8 endopod width, transverse suture in proximal half, 18 distal plumose setae, external margin 13 simple setae; endopod short oval, length 0.8 exopod length. Pleopod IV (Fig. 8C), exopod oval, as long as 1.9 width, external proximal margin with transverse suture, close to pleopod joint; endopod 0.9 exopod length. Pleopod V (Fig. 8D), exopod oval, length 1.8 width, transverse suture not evident; endopod length 0.9 length, width 0.9 exopod width. Pleotelson (Fig. 8E), subsquare, width 1.2 length, lateral margins parallel, with simple setae, caudomedial lobe broad rounded. Uropods (Fig. 8E), length 0.8 pleotelson length, armed with robust setae; endopod oval, as long as protopod; exopod length 0.9 protopod length. Habitat. This species was collected between roots of the water lily Eichornia crassipes, which floated in a channel of approximately 2 meters wide by one meter deep. Distribution. Known only from the type locality. Etymology. This species is named in honor to Dr. George D. F. Wilson (Buz), Saugatuck Natural History Laboratory, in recognition to his career with the isopods and for being a mentor and for his friendship with the first author. Remarks. Caecidotea buzwilsoni sp. nov. represents the first record of Caecidotea for the Mexican state of Guanajuato. Its morphology is similar to Caecidotea zacapuensis sp. nov. both species can be differentiated by the transverse suture of pleopod IV, which in Caecidotea zacapuensis sp. nov. is incomplete while in Caecidotea buzwilsoni sp. nov. is complete., Published as part of García-Vázquez, Leonardo, Pedraza-Lara, Carlos & Rodríguez-Almaraz, Gabino, 2021, Six new epigean species of Caecidotea (Isopoda: Asellidae) distributed along the Trans-Mexican Volcanic Belt in Central Mexico, pp. 45-77 in Zootaxa 4965 (1) on pages 53-56, DOI: 10.11646/zootaxa.4965.1.2, http://zenodo.org/record/4723078

The acanthocephalan parasite Acanthocephalus dirus infects the freshwater isopod Caecidotea intermedius as an intermediate host before completing its life cycle in a fish. Transmission to the definitive host occurs after the parasite has reached the cystacanth stage and development into this stage is associated with changes in several behavioral and physiological traits of the host. Despite the numerous examples of trait modification in this system, little is known about the multidimensional nature of this modification. Here, we examined the relationships between cystacanth infection, and expression of multiple traits (body color, refuge use, activity, and body size) of both male and female C. intermedius. The pattern of multidimensional modification was determined for males and females and then measures of behavioral plasticity, individual consistency, and trait correlations were obtained for the modified traits. The results revealed that the overall pattern of host modification differed between males and females. Infected males and females showed similar decreases in body color but differed in changes to the other traits. Infected females were larger and less active than uninfected females, whereas infected males spent less time in refuge than uninfected males. A comparison between two situations revealed that refuge use exhibited high levels of plasticity and activity exhibited high levels of consistency and that these patterns differed based on both host sex and infection status. Analysis of the relationships among modified traits showed that traits appeared to be modified independently of each other and that correlations between traits that existed in one situation were absent in another. We suggest that the pattern of multidimensional modification is sex-specific and that the traits are modified independently. We also show that the patterns of multidimensional modification were not associated with variation in either parasite intensity of parasite size indicting that competitive interactions among parasites did not appear to act as a constraint on host modification.

Decomposition of senesced primary production starts processing chains in aquatic systems. Shredding macroinvertebrates convert coarse particulate organic matter (CPOM) to fine particulate organic matter (FPOM) that supports 2 other feeding groups, collecting and filtering macroinvertebrates. This linkage is often invoked by aquatic ecologists, but the effect of detritivore assemblage composition on production of FPOM is relatively understudied. I manipulated detritivore assemblage composition (Limnephilus sp., Caecidotea sp., and Hyalella azteca) in aquatic mesocosms stocked with green speckled alder leaves (Alnus incana rugosa). I measured production rate, size distribution, and stoichiometry of FPOM produced through time. Detritivore species richness had a positive effect on FPOM production resulting from inclusion of the functionally dominant shredder, Limnephilus sp., in mixed-species treatments (e.g., sampling effect). Mixed-species treatments had significantly faster particle production than...

Mexistenasellus floridensis sp. n. is described from Hole in Wall Cave, Jackson County, Florida. The discovery of this unique isopod nearly doubles the range of the Family Stenasellidae in North America, which was previously known from Oaxaca, Mexico to southern Texas, USA. This is the first stenasellid reported swimming in the water column of a cave, a curious finding for an isopod that belongs to a group that is generally more adapted to inhabiting interstitial spaces. Mexistenasellus floridensis occurs syntopically with the subterranean asellid Caecidotea putea. Both species have been observed swimming in the water column, although neither has apparent anatomical adaptations for swimming as compared to the natatory pereopods of Remasellus parvus, an asellid that occurs in caves in Alachua, Madison and Wakulla counties, Florida.

A number of shallow groundwater habitats that occur in the Coastal Plain and Piedmont of the mid-Atlantic region are documented and described. These isolated tiny aquifers are underlain by clay (hypotelminorheic habitats) and exit at seepage springs, springs, tiled fields and tile drains, and shallow wells. These shallow groundwater habitats harbor species with reduced eyes and pigment that are limited to these habitats. The distribution of 23 such species—four planarians (Sphalloplana and Phagocata), one snail (Fontigens), 13 amphipods (Stygobromus), and five isopods (Caecidotea)—is documented, based on over 450 records. More species (16) were found in hypotelminorheic habitats than in other shallow groundwater habitats. Also, more species were found exclusively in either the Piedmont or Coastal Plain, but seven species were found along the boundary (Fall Line) between these physiographic provinces. Compared to surface waters in nearby habitats, hypotelminorheic water had higher conductivity, higher dissolved oxygen, and slightly lower pH.

Caecidotea xochimilca n. sp. is described from specimens found in the roots of the water hyacinth in Lake Xochimilco, Mexico City. There are two other epigean Mexican species: Caecidotea xochimilca n. sp. differs from C. williamsi Escobar-Briones & Alcocer, 2002 by the shape of the palmar processes on male pereopod 1, and the aesthetasc formula and number of flagellar articles in antenna 2. Caecidotea puebla Cole & Minkley, 1968 differs from the new species by the body proportions, the number of flagellar articles in antenna 1 and antenna 2, the flagellum of antenna 1 reaching to the distal border of the peduncle of antenna 2 when reflected, a lateral sinuosity in the exopod of pleopod 2 of the female, the number of setae in pleopods 4 and 5, and uropodal characters. A key for the Mexican species of the genus is given. Caecidotea xochimilca n. sp. es descrita de especimenes encontrados en la raiz de lirio acuatico del Lago de Xochimilco, Ciudad de Mexico. Hay otras dos especies Mexicanas epigeas. Caecidotea xochimilca n. sp. difiere de C. williamsi Escobar-Briones & Alcocer, 2002 por tener diferente la forma del proceso palmar del pereopodo 1 del macho, la formula de aestetascos y el numero de artejos flagelares en la antena 2. Caecidotea puebla Cole & Minkley, 1968 difiere de la especie nueva por la proporcion del cuerpo, el numero de artejos flagelares en la antena 1 y antena 2, el flagelo de la antena 1 cuando esta extendido alcanza el borde distal del pedunculo de la antena 2, la sinuosidad lateral en el exopodo del pleopodo 2 de la hembra, numero de setas en los pleopodos 4 y 5 y las caracteristicas del uropodo. Se proporciona una clave para especies mexicanas del genero.

Five species of subterranean asellid are known from Maryland: Caecidotea pricei, C. franzi, C. holsingeri, C. mausi and C. vandeli. Caecidotea nordeni, n. sp. is a subterranean species described from Washington Co., Maryland and assigned to the hobbsi Group. A new locality for C. franzi in Kentucky is presented. This species was previously known from two caves in Maryland and Pennsylvania. The newly discovered population represents a range extension of over 400 km. The male pleopod 2 morphology of specimens from a Maryland population of the subterranean asellid C. holsingeri is compared with populations from three caves in West Virginia. The range of C. holsingeri extends from eastern West Virginia and adjacent Virginia to Garrett Co., Maryland.

Mexistenasellus floridensis sp. n. is described from Hole in Wall Cave, Jackson County, Florida. The discovery of this unique isopod nearly doubles the range of the Family Stenasellidae in North America, which was previously known from Oaxaca, Mexico to southern Texas, USA. This is the first stenasellid reported swimming in the water column of a cave, a curious finding for an isopod that belongs to a group that is generally more adapted to inhabiting interstitial spaces. Mexistenasellus floridensis occurs syntopically with the subterranean asellid Caecidotea putea. Both species have been observed swimming in the water column, although neither has apparent anatomical adaptations for swimming as compared to the natatory pereopods of Remasellus parvus, an asellid that occurs in caves in Alachua, Madison and Wakulla counties, Florida.

The acanthocephalan parasite Acanthocephalus dirus develops from the egg to the cystacanth stage inside the freshwater isopod Caecidotea intermedius. We have shown previously that cystacanth-infected male C. intermedius are less likely to initiate mating attempts with females than uninfected males in competitive situations. Here, we used a field-based experiment to examine whether cystacanth-infected males were also less likely to initiate mating attempts with females in noncompetitive situations. We found that infected males were less responsive to females than uninfected males, and we propose that the cystacanth-related change in male mating behavior is mediated by a change in the mating response of males to females rather than male-male competition. We then examined whether cystacanth-related changes in reproductive function, i.e., sperm content and fertilization ability, could explain this variation in male mating behavior. We found that cystacanth-infected males contained both developing and mature sperm and fertilized as many eggs as uninfected males. Thus, we propose that changes in reproductive function are unlikely to explain cystacanth-related variation in male mating behavior in C. intermedius.

Caecidotea williamsi Escobar-Briones & Alcocer (2002) is the first asellid described from a saline aquatic habitat in America, Alchichica crater-lake, Puebla, Central Mexico. No previous reports exist for asellid isopods from inland saline waters in America in spite of the extensive research undertaken so far on the continent. Differing from other asellids, C. williamsi inhabits saline waters (i.e. 8.5 g l−1) dominated by sodium, magnesium, chloride, and bicarbonate ions and markedly alkaline (pH 9.0 ± 0.1). Water temperature ranges from 14.5°C throughout the water column in winter and in the deep waters for the rest of the year, up to 20°C in the surface waters in summer. C. williamsi occurs in a depth range of surface to 30 m (lake’s maximum depth is 64 m), below which an anoxic layer is found during 9 months of the year. Generally it lives cryptically in tufa crevices and at shallower depths many inhabit empty trichopteran cases embedded within the tufa crevices. Some specimens are heavily covered by epizooic ciliates on the thoracic and abdominal segments of the exoskeleton and the pleopods. Data are presented on the diet, possible predators, saprobity and trophism, and regional distribution of C. williamsi. The continued survival of this unique isopod is threatened by anthropogenic desiccation of its habitat.

The Flatwoods Salamander (Ambystoma cingulatum) was listed as a federally threatened species because loss and alteration of adult and larval habitats caused population declines. Current management plans for this species must include maintenance of appropriate larval habitat. However, much of the natural history of this species is poorly known. Our objective was to evaluate the diet of A. cingulatum larvae. We examined stomach contents of 122 larvae collected from Florida and South Carolina. We identified and measured invertebrate prey and estimated biomass using length-mass relationships. Crustaceans, mostly isopods (Caecidotea), amphipods (Crangonyx), cyclopoid copepods, and cladocerans (primarily Simocephalus and other daphnids) were the most abundant prey. Isopods and amphipods also dominated stomach content biomass because of their relatively large size. Stomachs of small A. cingulatum larvae had significantly higher numbers and proportions of cladocerans and smaller numbers and proportions of isopods compared to larger larvae (P < 0.05). Smaller larvae also had significantly lower amounts and proportions of isopod biomass in their guts compared to large larvae (P < 0.05). We found Hedruris siredonis, a parasitic nematode, in ∼11% of stomachs examined; this is a new host record for this parasite. Our results indicate that larvae feed primarily on freshwater crustaceans, particularly isopods, copepods, cladocerans, and amphipods. Management activities that adversely impact freshwater crustacean communities in breeding habitats, such as pesticide use or introductions of predatory fish, could adversely impact remaining populations of this salamander.

The amphipod Crangonyx floridanus and the isopods Caecidotea racovitzai and Asellus hilgendorfii were discovered in the Sacramento/San Joaquin Delta, California, U.S.A. We applied Chapman and Carlton's (1994) criteria for determining introduced species to test whether these species are non-indigenous to the delta. The majority of the attributes scored positive, indicating that these species are non-indigenous. These populations appear to be firmly established, as they occurred at a variety of freshwater wetland habitats throughout a one-year study. The species are briefly described, and distinguished from similar native and non-indigenous species known to exist in the surrounding area.

A new species of Caecidotea, an aquatic isopod crustacean is described from Alchichica crater-lake in the state of Puebla, Oriental Basin, central Mexico. This is the first report of an epigean asellid isopod, with cryptic behavior inhabiting inland saline waters in America. Comparisons made with other co-occurring asellid species in the region show that the species Caecidotea pasquinii differs from the new species in lacking eyes, having different features on the male endopod of pleopod 2, a shorter pereiopod 6, and having elongated uropods. The epigean species Caecidotea communis differs from the new species in having pleopod 4 of the A type pattern of Lewis & Bowman (1981) and 5–8 retinacula on pleopod 1 sympod.

Caecidotea mausi Lewis & Bowman, 2009 (in Lewis 2009) (Figs 1, 5 i) Range. This obligate subterranean species is known from two caves about 80 km apart in Washington Co., Maryland and adjacent Warren Co., Virginia (Lewis, 2009)., 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 62, DOI: 10.5281/zenodo.207750, {"references":["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."]}

Caecidotea vandeli (Bresson, 1955) (Figs 1, 5 g, 6) Material examined. MARYLAND: Frederick Co., Gum Spring, Brunswick Town Park, DJF, 16 April 1994, 33, 2 ��; Montgomery Co.: Edwards Ferry Spring # 11, 0.65km NE from mouth of Goose Creek, C& O NHP, DJF, 26 March 1996, 131��; northeast spring, Three Spring Hollow, C& O Canal, DJF, 1 April 1994, 13; same, southwest spring, 33, 3 ��; Washington Co.: Roundtop Hollow Mine # 2, DJF, 1 May 1992, 13; same locality, DJF, R. Bartgis, 11 June 1993, 23; spring # 1, Seneca Creek State Park, DJF, C. Lee, 16 March 1994, 53, 6 ��. Range. This species has been reported from seven counties in Virginia (Holsinger & Culver 1988; Lewis 2009). Similar to C. pricei, this species has dispersed from the Appalachians into the Piedmont. The relatively wide range of this species is probably related to its ability to disperse through non-cave groundwaters., 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":["Bresson, J. (1955) Un asellide nouveau de l'Amerique du Nord. Archives de Zoologie Experimentale et Generale, Notes et Revue, 94, 37 - 43.","Holsinger, J. R. & Culver, D. C. (1988) The invertebrate cave fauna of Virginia and a part of eastern Tennessee. Brimleyana, 14, 1 - 162.","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."]}

Caecidotea kenki (Bowman, 1967) (Figs 5 c, 6) Material examined. MARYLAND: Allegany Co., Cresatown, small stream behind high school, AN, 5 January 1980, 20��; Cumberland Blue Spring, DJF, 10 March 1989, 13��; Pinto Mine, deep pool of water in mine shaft, DJF, D. Grove, 29 July 1987 13; Potomac Blue Hole Spring, DJF, 9 June 1988, 53; Red Hill spring, DJF 26 May 1988, 232��; small spring, Dan���s Mountain, DJF, ET, no date, 237 ��; small spring feeding Murley Branch, DJF, 13 February 1988, 4��; two springs near Pinto Mine, DJF, 1 April 1988, 5��; Garrett Co.: spring near Junction of Westernport & Russell roads, AN, 16 August 1981, 52��; Bear Creek springs, DJF, 14 July 1989, 133��; Little Bear Creek springs, DJF, 12 July 1989, 9��; small spring fed pool in sandstone shelter, DJF, 5 March 1988, 131��; spring on north side of Salt Block Run, DJF, 15 February 1988, 19��; spring, unnamed tributary of Lower Savage River, DJF, 17 June 1991, 23, 2 ��; The Glades Spring, DJF, 22 May 1992, 6��; Vansicles Rock Spring, DJF 27 May 1992, 131��; Wolf Swamp spring, DJF., 10 June 1991, 10��; Montgomery Co.: spring at end of Susan Lane feeding Ruck Creek J. Hill, J. Royte, 13 April 1990, 82��; spring in Glen Echo Heights Quarry, DJF, 9 March 1996, 13; Washington Co.: Big Spring, DJF, 23 July 1988, 7��; Canal Culvert Spring, DJF, 14 April 1993, 3��; Cedar Grove Spring # 1, DJF, 14 April 1993, 4��; Flatworm Spring, DJF 19 April 1993, 5��; Indian Spring, DJF, 19 March 1989, 15��; Karst Window Spring, DJF 20 April 1993, 3��; Keedysville Spring, DJF, 23 July 1988, 20��; Lime Mill Spring, DJF, 29 April 1992, 23, 2 ��; Roundtop Hollow Spring, DJF, R. Bartgis, 11 June 1993, DJF, R. Bartgis, 1 ��; Roundtop Siding springs, DJF, no date, 4 ��. Range. This species is an inhabitant of springs and has been recorded from northern Virginia, the District of Columbia, Maryland and Pennsylvania (Bowman 1967). It is sympatric with C. alleghenyensis in western Maryland, but no cases of co-occurrence have yet been recorded. As noted by Lewis (2009), some populations (e.g., Glen Echo Springs) are stygomorphic., 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 pages 61-62, DOI: 10.5281/zenodo.207750, {"references":["Bowman, T. E. (1967) Asellus kenki, a new isopod crustacean from springs in the eastern United States. Proceedings of the Biological Society of Washington, 80, 131 - 140.","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."]}

Caecidotea nordeni Lewis & Bowman, 2010 (Figs 1, 5 d) Range. This species is known only from the type-locality, a spring stream near Ernstville, in Washington Co., Maryland. The eyeless, unpigmented appearance of this isopod indicates that it is a subterranean species, presumably discharged into the spring stream in which it was collected. Numerous attempts to find it again have been unsuccessful., 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 62, DOI: 10.5281/zenodo.207750, {"references":["Lewis, J. J. (2010) The subterranean asellids of Maryland: Description of Caecidotea nordeni, new species, and new records of C. holsingeri and C. franzi ((Crustacea: Malacostraca: Asellidae). Journal of Cave and Karst Studies, 72, 100 - 104."]}

Caecidotea alleghenyensis Lewis & Bowman, new species (Figs 1���4, 5 a���b, 6) Material examined. MARYLAND: Garrett Co., Holotype: 8.8 mm 3, Swallow Falls State Park, spring # 1, Daniel J. Feller (DJF), 20 May 1992 (USNM 1138994). Paratypes: 113, 3 ��, same data as holotype (USNM 1138995). Other material: Spring 35 meters south of Swallow Falls Road, opposite entrance to Maple Glade Road, A. W. Norden (AWN), B. Norden, 17 September 1978, 35�� (USNM 1138996); springs feeding Deep Creek along west side of Oakland-Sang Road, E. Thompson (ET), 4 April 1986, 13, 4 �� (USNM 1138997); spring flowing into tributary of Herrington Run, DJF, ET, 15 May 1987, 113, 3 �� (USNM 1138998); same locality, DJF, 16 May 1987, 233�� (USNM 1138999); spring between Herrington Manor Road & Zenas Mellott Road, outlet 0.2 mile [0.3km] SE of Junction, Swallow Falls State Forest, DJF, 17 May 1987, 23 (USNM 1139000); springs between Herrington Manor Road & Zenas Mellott Road, outlets 0.3, 0.5 and 0.7 mile [0.5, 0.8 and 1.1km] SE of Junction (3 vials), Swallow Falls State Forest, DJF, 20 May 1987, 33 (USNM 1139001); 334 �� (USNM 1139002); 233 �� (USNM 1139003); spring flowing into tributary of Chisolm Run 1.1 [1.8km] miles east of Hutton (2 vials), DJF, ET, 17 June 1987, 537�� (USNM 1139004); 734 �� (USNM 1139005); spring below John Friend Cave, DJF, 3 March 1988, 33, 5 �� (USNM 1139006); spring flowing into Sang Run, DJF, 5 March 1988, 13, 1 ��; Herrington Run Spring Complex, DJF, 11 May 1988, 13 (USNM 1139007); spring along Deep Creek, ca. 0.3 miles [0.5km] W Oakland-Sang Run Road, DJF, 4 October 1989, 534�� (USNM 1139008); spring at confluence of Muddy Creek and Youghiogeny River, AN, 29 August 1993, 43, 4 �� (USNM 1139009); Swallow Falls spring, AWN, 29 August 1993, 36�� (USNM 1139010). Diagnosis. Member of the hobbsi Group of Caecidotea (Lewis 1982, 2009), with male gnathopod propodus armed with well developed processes. Pleopod 1 exopod with plumose setae along distal margin. Pleopod 2 endopod tip with cannula extending parallel to the axis of the endopod, obscured by broadly rounded mesial process and smaller lateral process. Uropods shorter than pleotelson. Description of male. Longest to 9 mm, approximately 3.6X as long as wide. Body appears unpigmented to naked eye, dorsum of head and pereonites with light diffuse pigmentation under low magnification, most pronounced on head, then decreasing progressively from pereonites 1���4. Eyes small, but distinct and pigmented. Margins of head, pereonites and pleotelson densely setose. Head approximately 1.8X as wide as long, pleotelson moderately produced. Pleotelson slightly longer than wide. Antenna 1 extending to middle of last article of antenna 2 peduncle, flagellum to 10 articles, distal 3 each with 1 esthete. Antenna 2, penultimate article of peduncle about 2 / 3 length of distal article, flagellum to 50 articles, reaching to pereonite 7 when bent. Mouthparts per diagnosis of genus (Lewis 2009). Pereopod 1, propodus 1.4X as long as wide, palmar margin proximally with low, stout setae, mature adult with large blade-shaped median process extending well beyond outer margin of recumbent dactyl, distal bicuspid process lower in height relative to median process. Pleopod 1, protopod approximately 0.6X length of exopod, with 3 retinacula. Exopod approximately 2 X as long as wide, lateral margin weakly concave, 3 very elongate plumose setae along distal margin. Pleopod 2, exopod distal article with approximately 20 + elongate plumose setae along margins. Endopod with rounded basal apophysis of varying prominence, tip with 4 processes in anterior view: (1) cannula low, conical, obscured; (2) mesial process broadly rounded, (3) lateral process similar to mesial process, lower and smaller; (4) caudal process broadly rounded forming apex of endopod. Pleopod 3 exopod, proximolateral margin with non-plumose setae, distolateral and apical margin with plumose setae increasing in size toward apical margin. Pleopod 4 exopod with transverse false suture, proximolateral margin with numerous non-plumose setae of moderate length. Pleopod 5 exopod, proximolateral margin with 3 non-plumose elongate setae. Uropods 0.75 length of pleotelson, protopod spatulate, about equidistant in length with endopod, exopod 0.75X length of endopod. Etymology. The name refers to the Allegheny Mountains. The suggested vernacular name is the Allegheny spring isopod. Range. Known only from the Allegheny Mountains of western Maryland. Ecological notes. This species is known only from springs, where it was found associated with leaf litter and decaying wood. Ovigerous females were present in collections from May and June, and ranged in size from 3.8 to 6.2 mm in length., 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 pages 55-61, DOI: 10.5281/zenodo.207750, {"references":["Lewis, J. J. (1982) A diagnosis of the hobbsi Group, with descriptions of Caecidotea teresae, n. sp., and C. macropropoda Chase and Blair (Crustacea: Isopoda: Asellidae). Proceedings of the Biological Society of Washington, 95 (2), 338 - 346.","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."]}

Caecidotea franzi (Holsinger & Steeves, 1971) (Figs 1, 5 f, 6) Material examined. MARYLAND: Allegany Co., Fort Hill Spring, AWN, 27 June 1985, 33, 2 ��; same locality, DJF, 23 June 1990, 63, 3 ��; Pinto Mine, deep pool of water in mine shaft, DJF, D. Grove, 29 July 1987, 1312��. WEST VIRGINIA: Mineral Co., Kites Cave, DJF, 11 June 1992, 23, 6 ��. Range. This species occurs in western Maryland and adjacent West Virginia, with disjunct populations in Centre Co., Pennsylvania and Harlan Co., Kentucky (Lewis 2010)., 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 61, DOI: 10.5281/zenodo.207750, {"references":["Holsinger, J. R. & Steeves, H. R. (1971) A new species of subterranean isopod crustacean (Asellidae) from the central Appalachians, with remarks on the distribution of other Isopods in the region. Proceedings of the Biological Society of Washington, 84,189 - 200.","Lewis, J. J. (2010) The subterranean asellids of Maryland: Description of Caecidotea nordeni, new species, and new records of C. holsingeri and C. franzi ((Crustacea: Malacostraca: Asellidae). Journal of Cave and Karst Studies, 72, 100 - 104."]}

Caecidotea pricei Levi, 1949 (Figs 1, 5 e, 6) Material examined. MARYLAND: Cecil Co., Folks Pond Spring, DJF, 14 April 2010, 434��; Montgomery Co., Chilton Woods Spring # 8, DJF, 15 April 1994, 133��; Chilton Woods Spring # 9, DJF, 15 April 1994, 336��; Chilton Woods Spring # 10, DJF, 15 April 1994, 332��; Washington Co., Antietam Quarry Spring, DJF, 13 April 1993; 4 ��; Artz Cave, DJF, 17 June 1992, 13; Canal Culvert Spring, DJF, 14 April 1993, 3��; Cedar Bluff Spring, DJF, 29 April 1992, 6��; Dargan Seep # 2, DJF, 13 April 1992, 8��; Dargan Spring, DJF, 13 April 1993, 10��; Dellinger Culvert Spring, DJF, R. Bartgis, 28 April 1993, 4��; Flatworm Spring, DJF 19 April 1993, 6��; Hagerstown City Park Pond Springs, DJF, 11 Oct 1989, 3��; Howell Cave, DJF, 23 June 1989, 2��; Karst Window Spring, DJF 20 April 1993, 8��; Kemps Spring # 1, DJF 28 March 1989, 4��; Kemps Spring # 2, DJF, 28 March 1989, 235��; Kemps Spring # 3, DJF, 28 March 1989, 10 ��; Lime Mill Spring, DJF, 29 April 1992, 3��; Neck Bluff Spring # 1, DJF, R. Bartgis, 28 April 1993, 2��; Neck Bluff Spring # 2, DJF, R. Bartgis, 28 April 1993, 8��; Neck Spring near Falling Waters Road, DJF, 22 March 1989, 233��; Quarry Spring, DJF, 5 February 1992; 5 ��; Sump Spring, DJF, R. Bartgis, 28 April 1993, 9��; Two Locks Spring # 2, DJF, 28 April 1992, 131��; Watercress Pool Spring, DJF, 29 April 1992, 23; Williamsport Spring, DJF, 28 March 1989, 123. Range. As indicated by the records above, this is the predominant stygobiotic Caecidotea in the Ridge and Valley region of Maryland. It occurs in Virginia and adjacent West Virginia, through Maryland into Pennsylvania. In the latter two states C. pricei has crossed the Blue Ridge into the Piedmont (Steeves 1969; Lewis 2009)., 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 pages 62-63, DOI: 10.5281/zenodo.207750, {"references":["Levi, H. (1949) Two new species of cave isopods from Pennsylvania. Notulae of the Academy of Natural Sciences of Philadelphia, 220, 1 - 6.","Steeves, H. R. (1969) The origin and affinities of the troglobitic asellids of the southern Appalachians. Pages 51 - 65, in P. C. H olt (editor), The distribution history of the biota of the southern Appalachians. Part 1. Invertebrates. Virginia Polytechnic Institute and State University, Research Division Monograph 1.","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."]}

Caecidotea holsingeri (Steeves, 1963) (Figs 1, 5 h, 6) Material examined. MARYLAND: Garrett Co., John Friend Cave, DJF, D. Hubbard, 29 August 1992, 33. Range. Summarized by Lewis (2009, 2010) and Fong et al. (2009) this species occurs primarily in caves from southwestern Virginia through eastern West Virginia, to Garrett Co., Maryland., 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 61, DOI: 10.5281/zenodo.207750, {"references":["Steeves, H. R. (1963) Two new species of troglobitic asellids from West Virginia. American Midland Naturalist, 70 (2), 462 - 465.","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.","Lewis, J. J. (2010) The subterranean asellids of Maryland: Description of Caecidotea nordeni, new species, and new records of C. holsingeri and C. franzi ((Crustacea: Malacostraca: Asellidae). Journal of Cave and Karst Studies, 72, 100 - 104.","Fong, D. W., Culver, D. C., Hobbs, H. H. & Pipan, T. (2009) The invertebrate cave fauna of West Virginia, Second edition. West Virginia Speleological Society Bulletin, 16, 163 pp."]}

The mechanisms of leaf decay, leaf-associated macroinvertebrate community structure, leaf-associated microbial activity and physicochemical stream characteristics were investigated on a mid-Michigan headwater stream in summer. An undisturbed wooded site was compared with two agriculturally perturbed sites. Discharge, total suspended particulates, and nutrients were all higher and more variable throughout the season within the agricultural reaches. Leaf decay rates were higher at the agricultural sites and results suggest discharge abrasion was the major leaf processing mechanism at these sites while microbial decay and macroinvertebrate shredding appear to be the primary mediators of leaf weight loss at the wooded site. Total macroinvertebrate densities on leaf packs at the agricultural sites were 1.9 times the densities at the wooded site. It is suggested that experimentally introduced leaf packs acted as a lure for net-spinning invertebrates limited by stable substratum at the agricultural sites. Species shifts were observed from wooded reaches where Pychnopsyche spp., Gammarus, Ephemeroptera, Bezzia, and Nigronia serricornis were important, to downstream agricultural reaches which were dominated by Cheumatopsyche, Chironomidae, Elmidae, Hydracarina, Hemerodromia, and Caecidotea.

The isopod Caecidotea intermedius serves as the intermediate host for the acanthocephalan Acanthocephalus dirus. C. intermedius is preyed upon by the northern creek chub, Semotilus atromaculatus, which also serves as the definitive host for A. dirus. The effects of the parasite on the antipredator behavior of C. intermedius were examined. We tested the hypothesis that behavioral changes induced in C. intermedius by the parasite are by-products of increased energy demands induced by the parasite (i.e., increased hunger). Infected and uninfected C. intermedius were placed in a divided aquarium with 0, 1, or 2 creek chubs. Leaf discs provided both a food source and a refuge from the predator. In the presence of the creek chubs, uninfected C. intermedius avoided the predator, and were found more frequently in refugia as the number of creek chubs increased. However, infected C. intermedius were associated with the side of the aquarium containing the predator, and spent significantly more time out in the open away from the refuge regardless of the number of creek chubs. These data show that the antipredator behavior exhibited by C. intermedius is altered by A. dirus, and that such alterations are unlikely to be simply products of increased energy demands. Parasite-induced behavioral changes appear to increase C. intermedius' vulnerability to predation, thereby increasing the likelihood of A. dirus completing its life cycle. We find little evidence for greater foraging need as the mechanism indicating changes in antipredator behavior.

"El presente trabajo reconoce la composición, estructura y distribución espacial del ensamble de crustáceos bentónicos de Alchichica, un lago salino tropical ubicado en el extremo oriental del altiplano mexicano. El lago presenta una riqueza taxonómica de crustáceos bentónicos compuesta por 1 anfípodo (Hyalella azteca), 1 isópodo (Caecidotea williamsi) y 2 ostrácodos (Limnocythere inopinata y Candona sp.). Comparada con otros lagos tropicales, la riqueza de especies es reducida. A pesar de lo anterior, es importante mencionar el grado elevado de endemismo representado por C. williamsi, recientemente descrita para el lago Alchichica; adicionalmente, es factible que tanto Candona como H. azteca sean especies nuevas y endémicas del lago. Los crustáceos bentónicos se distribuyen desde la zona litoral hasta la zona más profunda del lago (62 m) con abundancias y riqueza taxonómica variables. Los ostrácodos fueron los crustáceos que con mayor frecuencia se recolectaron en el lago, en la zona litoral, en el talud, y en la zona profunda de la que son habitantesexclusivos. Los anfípodos constituyeron el segundo grupo en abundancia de la zona litoral y talud y estuvieron ausentes en la zona profunda. Los isópodos sólo se encuentran asociados a los depósitos de tufa, hábitat característico del lago que se extiende a lo largo del talud, por lo que con las técnicas de muestreo tradicional empleadas en el presente estudio no fueron capturados. En este ensamble de crustáceos predominan las especies de desarrollo directo y con posiciones tróficas que incluyen componentes herbívoros (H. azteca), omnívoros (C. williamsi) y bacterívoros (L. inopinata y Candona sp.)."

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.

Density of troglobitic crustaceans and levels of potential food sources were compared in reference pools and pools polluted by septic system effluent in Banners Corner Cave, Virginia. Data from four physicochemical variables indicated slight to high pollution in five pools compared with two unpolluted pools. Polluted pools had high levels of conductivity, nutrients and fecal coliforms. Highly polluted pools also had decreased dissolved oxygen levels. Isopods (Caecidotea recurvata) were absent from highly polluted pools. Highest isopod density (up to 74.6/M2) occurred in slightly and moderately polluted pools. Amphipods (Stygobromus mackini) were absent from all polluted pools. Fungal biomass was negligible in all pools. Bacterial biomass accounted for a greater proportion of sediment total organic matter (TOM) in polluted pools, but there was little overall increase in TOM in polluted pools. Results of a laboratory growth experiment suggest that isopods can use bacteria from septic effluent as a food. However, presence of coarse particulate matter, not organic enrichment by septic system effluent, was the most likely cause of high isopod density in some pools. Septic system effluent may provide additional food to the aquatic community in Banners Corner Cave, but generally was damaging to the system.

The interspecific interactions of three pairs of cave isopods and amphipods, previously thought to be competitors, were examined by analyzing washouts and losses from laboratory streams and from manipulation experiments in streams of Organ Cave, West Virginia. None of the pairs were in fact competitors. The isopod Caecidotea holsingeri was an amensalist of the amphipod Stygobromus spinatus in the laboratory, but the two did not interact in the field. The amphipod Gammarus minus was a predator on C. holsingeri both in laboratory streams and in the field, and C. holsingeri was a competitor of G. minus, at least in laboratory streams. Stygobromus emarginatus was an amensalist of G. minus in laboratory streams and in the field; but in the field G. minus was a commensalist of S. emarginatus. This combination of commensalism and amensalism produces the dynamics of a predator-prey system. Interactions in both laboratory streams and cave streams were asymmetric and often had characteristics of several kinds of interspecific interactions. Negative interactions dominated in laboratory streams while positive interactions were more common in the field experiments. Negative interactions had an effect on microdistribution only at the level of individual stones in a riffle. Positive interactions may contribute to the positive association of some species at larger scales.

Fifty-five percent of 201 Caecidotea intermedius (Crustacea: Isopoda) collected in McLean County, Illinois were infected with larvae of Acanthocephalus dirus. Through measurements of isopod total length and first pereiopod propodus and dactylus lengths, I found that mean total length of infected female isopods was significantly greater (Student's t-test, a = 0.05) than that of uninfected females. Mean total length of infected male isopods was significantly less (Student's t-test, a = 0.05) than that of uninfected isopods. Corresponding differences were noted for first pereiopod propodus and dactylus lengths. Regression analyses demonstrated significant (F-test, a = 0.001) linear relationships between first pereiopod propodus or dactylus lengths and isopod total lengths for uninfected, male worm-infected, and female worm-infected isopods of both sexes. The maintenance of such relationships during infection was indicated by the lack of statistically significant (a = 0.05) differences between regression or correlation coefficients. Acanthocephalan volume (mm3) did not differ significantly (Student's t-test, a = 0.05) for either sex of worm from male or female isopods. A statistically significant linear relationship was demonstrated (regression analysis) between female acanthocephalan volume and male isopod total length. Infection affected reproductive behavior of C. intermedius; infected isopods were never observed in amplexus and ovaries of infected females did not develop. Kuris (1974) and Baudoin (1975) reviewed the topic of parasitic castration for various invertebrates. There also are reports of parasite-induced host gigantism (see Cheng, 1971 for a review; Pearre, 1976). That the topics of parasitic castration and gigantism are complementary aspects of some host-parasite relationships has been suggested by Baudoin (1975) and supported by Pearre (1976, for a consideration of chaetognaths infected with larval trematodes). In an investigation (Oetinger & Nickol, 1981, 1982a,b) of altered pigmentation of Caecidotea intermedius Forbes, 1876 (Isopoda: Asellidae) infected with Acanthocephalus dirus (Van Cleave, 1931) (Acanthocephala: Echinorhynchidae), various additional features of the relationship were noted and are presented in this report in an attempt to evaluate some of the assumptions of parasitic castration/gigantism described by Baudoin (1975). MATERIALS AND METHODS Caecidotea intermedius were collected by dip net from overhanging vegetation along the banks of Sugar Creek, McLean County, Illinois. In the labo1 Publication costs, in part, are being met by a grant from the Spencer-Tolles Fund of the American Microscopical Society. 2 Present address: Department of Biology, Kentucky Wesleyan College, Owensboro, Kentucky 42302-1039, U.S.A. TRANS. AM. MICROSC. SOC., 106(3): 240-248. 1987. ? Copyright, 1987, by the American Microscopical Society, Inc. This content downloaded from 157.55.39.45 on Thu, 01 Sep 2016 04:47:07 UTC All use subject to http://about.jstor.org/terms VOL. 106, NO. 3, JULY 1987 ratory, isopods were placed in plastic boxes with aged tapwater and a source of aeration. Elodea, various filamentous algae, and decaying leaves were added for food. Water was changed daily and cultures were maintained at room temperature (20-25?C). All 201 isopods collected were examined within two weeks. Examination involved: (1) determination of isopod sex; (2) measurement of isopod total length (to the nearest 0.5 mm from the anterior margin of the cephalothorax to the posterior margin of the abdomen); and (3) dissection by separating body segments-first the cephalothorax and free thoracic segment 1 (T1), T2 and 3, T4 and 5, T6 and 7, and finally, the abdomen. Isopod body parts and acanthocephalans were processed as described previously (see Oetinger & Nickol, 1981). Outline drawings of propodus with dactylus, and acanthocephalans were made with a Rayoscope? microprojector to an enlargement of x 40. Propodus and dactylus lengths of left and right pereiopods were determined as indicated in Fig. 1. Acanthocephalan length was determined with a piece of waxed string placed along the mid-longitudinal axis of the drawing and subsequently measured with a metric rule. Width was measured at the point of greatest width directly on the drawing. Volumes of acanthocephalans were approximated with the formula of a prolate spheroid (V = 4/37rab2, where 2a = worm length and 2b = worm width-after Chen, 1934). Data for uninfected male isopods were reduced from the actual 70 such specimens to 25 using a random number table. Data for the female isopods and infected male isopods represent most of the isopods for each category occurring in the collection. Isopods lacking both first pereiopods were omitted from the data analyses (one male isopod with a male parasite and three male isopods with female worm infections). Analyses of data were carried out utilizing the conversational monitoring system "statistical package" of an IBM 360 computer. Weighted Student's t-tests were used when there were significant differences in variance.

On December 27, 1935, a large new Caecidotea was found in a 6mall stream in a cave five miles south of Kansas, Oklahoma. The stream pursues a very narrow and rocky course, and, at this time of year, being nowhere niore than two feet wide or eight inches deep, until it emerges upon a bed of guano some fifty feet from the mouth of the cave. It was in this shallow, muddy area that the greatest aggregation of Caecidotea was found, doubtless due to the fact that more organic matter which would serve as food was here available. In this pool were also found great numbers of a new species of white turbellarian, (which is being described by Dr. Libbie Hyman), and numerous larvae of Eurycea lucifuga and Eurycea melanopleura. In several instances, many of the turbellarians were seen aggregated in one spot, and, in each instance, a dead Caecidotea was found upon which the former seemed to be feeding. In the small rocky stream the Isopods and flat-worms were found in diminished numbers, but the Eurycea larvae tended to give way to Typhlotriton as the muddy pool was left behind. A number of the specimens of the Isopods and salamander larvae were taken and kept alive for well over a month. The Caecidotea seem to be able to stand considerable temperature changes with no ill effects as the specimens were several times inadvertently left in a hot room until the temperature of the water had risen to a point far above that to which they were accustomed. One of the salamander larva kept with the Isopods was one day observed eating a Caecidotea, but whether it was taken alive remained a question. It has been noticed that many of the Isopods taken have one or. both of the terminal appendages missing. Observation seems to indicate that this is due not only to attacks by salamander larvae but to the isopods fighting among themselves. The first walking leg is modified as a formidable offensive weapon and the captive specimens have at several times been seen attacking one another.

TWO species of crayfish are common in the caves of southern Indiana, often coexisting in the same cave (Eberly, 1954, 1955). Orconectes pellucidus (a somewhat variable species with several subspecies already designated by various workers) is the famous blind white cave crayfish found originally in Mammoth Cave. The other species is a form of Cambarus bartoni which,has up to the present been identified as C. bartoni laevis. Both of these species are ecological equivalents, and when they occur in the same cave come into direct competition with each other. The main environmental factor involved in this competition is food which is naturally scarce in caves. The chief food seems to be slow-moving isopods of the genus Caecidotea. However, C. bartoni, being much larger and more powerful, can and occasionally does kill and eat the other crayfish and is even cannibalistic at times. In this intense but slow-moving drama of the survival of the fittest, only one species seems destined to survive. Food is too scarce to permit both species to maintain very large populations side by side. The outcome will depend on the degree of specialization or adaptation to the cave environment. The usual cave adaptations are well known. The characters most relevant to this discussion are the following