Cambarus clivosus, Taylor and Soucek
Taylor, Christopher A., Soucek, David J. & Organ, Edward L., 2006, A new crayfish of the genus Cambarus Erichson, 1846 (Decapoda: Cambaridae) from an under-sampled habitat type in central Ten- nessee, USA, Zootaxa 1200, pp. 29-41: 31-41
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|Cambarus clivosus, Taylor and Soucek|
Cambarus clivosus, Taylor and Soucek new species
Figs. 2, 3, Table 1
Diagnosis.—Body and eyes pigmented. Rostrum triangular and moderately excavated, terminating in short, upturned acumen, weakly decurved in lateral view; median carina absent. Rostral margins thickened and bordered mesially with tufts of short setae; margins straight and converging. Areola 33.3–39.2 % (= 37.0, n = 38, SD = 1.5) of total length of carapace (CL = distance from distal tip of acumen to dorsocaudal edge of cephalothorax) and 38.9–44.3 % (= 42.3, n = 40, SD = 1.3) of postorbital carapace length (PCL = distance from anteriolateral edge of cephalothorax immediately behind eye to dorsocaudal edge of cephalothorax)). Areola sparsely punctate, narrowest at midpoint, 6.4–11.8 (= 8.6, n = 35, SD = 1.2) times as long as wide with 2 to 4 (mode = 3, n = 35, SD = 0.2) punctations across narrowest part (Fig. 2A). Postorbital carapace length 84.4– 89.7 % (= 87.6, n = 40, SD = 1.2) of CL. Cervical spines absent. Postorbital ridges low with smoothly rounded terminal ends (Fig. 2A). Suborbital angle approximately 90 degrees or slightly larger. Antennal scale broadest distal to midlength, distal margin either nearly perpendicular to lateral margin or angular to lateral margin (see Variation), thickened lateral margin terminating in short corneous spine (Figs. 2E, 2F). Incisor region of mandible deeply indented with two large cusps. Cephalomedian lobe of epistome bellshaped with small, triangular cephalomedian projection; epistomal zygoma strongly arched. Ischia of third pereiopods of males with large hooks, hooks overreaching basioischial articulation in form I males only. Coxa of fourth pereiopods of males with caudomesial boss. Chela with 1 row of tubercles (see Variation) along mesial margin of palm forming cristiform row, usually 6 or 7 tubercles (range 5–8, mode = 6, n = 40, SD = 0.6) in row; small tufts of setae along opposable margins, and dorsal, lateral, and mesial surfaces of fingers; dorsal surfaces of fingers with well defined longitudinal ridges (Fig. 2H).
First pleopods of form I male symmetrical and continuous at bases (Fig. 2I), extending to midpoint of bases of third pereiopods when abdomen flexed. First pleopod of form I male terminating in two elements: corneous central projection strongly recurved caudodistally at an angle of approximately 110 degrees, bladelike, with subapical notch, and reaching proximally to or just beyond distal base of mesial process (Fig. 2J); mesial process noncorneous, bulbous at base, distal end with multiple caudodistally directed small projections, distal half directed caudolaterally at 15 to 25 degrees, proximal edge usually at 90 degree angle to main axis of pleopod. First pleopod of form II male noncorneous, both elements arched caudodistally at 90 degrees to main axis of pleopod: mesial process of larger individuals directed caudolaterally at 15 to 25 degrees (Fig. 2G). Annulus ventralis immovable, subrhomboidal; cephalic half with wide median trough; caudal half strongly elevated; transverse fossa well defined with tongue extending either dextrally or sinistrally, disappearing under caudolateral wall; sinuate sinus running from center of fossa to caudal edge (Fig. 2D). view of right antennal scale; F, Dorsal view of right antennal scale; G, Lateral view of first pleopod of form II male; H, Dorsal view of right chela; I, Caudal view of first pleopods of form I male; J, Mesial view of first pleopod of form I male. A, C, F, H, I and J of holotype (INHS 10235); D, E of allotype ( INHS 10236View Materials) ; G of morphotype ( INHS 10232View Materials) .
Description of holotypic male, form I.—Body depressed dorsoventrally, at widest points carapace wider than abdomen (14.2 and 12.0 mm, respectively). Greatest width of carapace larger than height at caudodorsal margin of cervical groove (14.2 and 10.5 mm, respectively). Postorbital carapace length 88.3% of total length of carapace. Areola 8.8 times longer (10.5 mm) than wide (1.2 mm) with 3 punctations across narrowest part; length of areola 38.5% of total length of carapace. Rostrum moderately excavated dorsally, floor smooth, lacking carina; margins thickened, straight and converging. Each margin bordered mesially by row of tufts of short setae. Acumen short and terminating in small corneous spine, reaching just posterior to distal margin of third antennal endopod. Postorbital ridges weakly developed, termini smoothly rounded and lacking spine or tubercle. Suborbital angles approximately 90 degrees. Cervical spines or tubercles absent. Branchiostegal areas and lateral surfaces of carapace covered with low tubercles, tubercles in branchiostegal areas larger than those on lateral surfaces.
Abdomen longer than carapace (28.1 and 27.3 mm, respectively). Anteriolateral margins of pleura smoothly rounded, posteriolateral margins of second, fourth, and fifth segments rounded, posteriolateral margin of third segment slightly angular. Cephalic section of telson bearing 3 spines in each caudolateral corner, more mesial pairs movable.
Proximal podomere of uropod with large spine extending over mesial ramus and small spine in caudolateral corner extending over lateral ramus. Caudal margin of cephalic section of lateral ramus with 10 fixed spines and 1 movable spine in caudolateral corner, cephalic and caudal sections of lateral ramus with median ridge. Lateral margin of mesial ramus terminating in spine; mesial ramus with prominent median ridge terminating in premarginal spine. Dorsal surfaces of telson and uropods setiferous.
Antennal scale with distal margin nearly perpendicular to lateral margin, as in Diagnosis in other respects. Right antennal scale 3.5 mm long, 1.4 mm wide. Epistome as in Diagnosis.
Lateral margin of right chela slightly indented near base of fixed finger of propodus; mesial surface of palm with single cristiform row of 8 tubercles; dorsodistal margin of palm region at base of dactyl with two large bulbous tubercles (Fig. 2H). Mesial and lateral surfaces of chela, dorsal and ventral surfaces of fingers, and opposable margins of fingers covered with setiferous punctations. Dorsal surface of finger of propodus with strong submedian longitudinal ridge flanked by setiferous punctations; basal half of opposable margin with 3 tubercles which gradually increase in size, third tubercle from base of finger largest, 1 corneous tubercle just distal to midlength between third tubercle and distal tip of finger. Dorsal surface of dactyl with strong submedian longitudinal ridge flanked by setiferous punctations; basal half of opposable margin with 4 tubercles of equal size, tubercles smaller than largest tubercle on opposable margin of propodus. Finger of propodus and dactyl with subterminal corneous tip.
Right carpus with deep oblique furrow dorsally; mesial margin with 1 large and 2 small spines, large spine distalmost; ventral surface with 1 small centrally located spine. Ventral surface of merus with 1 large corneous spine at distolateral corner and mesial row of 7 spines; row terminating in large corneous spine. Ischium with 1 weak tubercle just proximal to midlength of mesial margin.
Hook on ischium of third pereiopod only; hook long, overreaching basioischial articulation, not opposed by tubercle on basis. First pleopods of form I male symmetrical and continuous at bases (Fig. 2I), extending to midpoint of bases of third pereiopods when abdomen flexed. First pleopod of form I male as described in Diagnosis but with distal half of mesial process directed caudolaterally approximately 15 degrees, proximal edge at 90 degree angle to main axis of the pleopod. ( Fig. 1JView FIGURE 1).
Description of allotypic female.—Differing from holotype as follows: Areola constituting 38.8% of length of carapace and 9.8 times longer than wide. Postorbital carapace length 89.0% of length of carapace. Mesial surface of palm of right chela with single row of 7 tubercles. Caudal margin of cephalic section of lateral ramus of uropod with 9 fixed spines. Distal margin of antennal scale angular to lateral margin (Fig. 2E).
Sternum between third and fourth pereiopods narrowly Vshaped. Annulus as described in Diagnosis but with tongue in sulcus extending sinistrally. First pleopod uniramous, barely reaching caudal margin of annulus when abdomen flexed.
Description of morphotypic male, form II.—Differing from holotype as follows: Areola constituting 36.4% of length of carapace, 9.7 times longer than wide. Postorbital carapace length 87.1% of length of carapace. Mesial surface of palm of right chela with single row of 7 tubercles, 2 proximalmost tubercles fused. Ventral surface of merus with mesial row of 6 spines and 2 spines in distolateral corner. Caudal margin of cephalic section of lateral ramus of uropod with 9 fixed spines.
Hook on ischium of third pereiopod short, not overreaching basioischial articulation. First pleopod as described in Diagnosis.
Size.—The largest specimen examined is a 35.0 mm CL female. Females (n = 16) range in size from 11.9 to 35.0 mm CL. Form I males (n = 10) range from 19.7 to 28.2 mm CL. Form II males (n = 9) range from 13.3 to 28.0 mm CL.
Color.— Base color of dorsal and lateral surfaces of chelae, cephalothorax, abdomen, pereiopods, and tail fan rather uniform and light to dark brown ( Fig. 3View FIGURE 3). Dorsal surface of abdominal segments 1 through 5 usually darker brown than base color, giving the appearance of dark wedge running down center of dorsum. Pleurites of first abdominal segment cream colored. Tubercles on chelae and spines on carpus light orange or cream colored. Rostral margins orange or crimson red ( Fig. 3View FIGURE 3). Faint Ushaped saddle centered at caudal edge of cephalothorax and extending cephalically may be present on individuals with light brown base color. Ventral surfaces of chelae, cephalothorax, and abdomen cream to white.
Type locality.—Seepfed tributary of Dry Creek at Pea Ridge Wildlife Management Area, approximately 11.5 km WSW Smithville, De Kalb County, Tennessee (35.9205°N, 85.9271°W NAD 83). The tributary lies in a densely wooded ravine with walls that sloped at approximately 60 degrees. The holotype was collected from under a piece of flat rock in midchannel while the allotype was collected from a shallow burrow dug into the stream bank. The morphotype was collected from another site. At the type locality, the seepfed creek was approximately 0.5 m wide with gravel and smallsized cobble and shale substrates. Rock outcroppings occurred along both banks. Water depth was 1 to 3 cm and flow was not constant in all stretches.
Disposition of types.—The holotype, allotype, and morphotype are deposited in the Illinois Natural History Survey Crustacean Collection as INHS 10235, INHS 10236, and INHS 10232, respectively, as are the following paratypes: 1 MI and 1F, INHS 10237. Paratypes are deposited at the National Museum of Natural History, Smithsonian Institution, Washington, D. C. as follows: 1 MI, 1 MII, and 1 F, USNM 1083161. The localities and dates of collection for paratypes and morphotype are provided in the following Range and specimens examined section.
Range and specimens examined.— Cambarus clivosus , new species, is currently known to occur in a portion of the Eastern Highland Rim in central Tennessee ( Fig. 4View FIGURE 4). The species seems to be restricted to a narrow (14 km wide) peninsula of elevated Mississipian age limestone fortified with chert and shale formations ( Etnier and Starnes 1993) that extends southsouthwestward from the Highland Rim through the counties of De Kalb and Cannon. Creeks in the peninsula are characterized by chert gravel and sand substrates interspersed with areas of bedrock and drain to the north and east into the Caney Fork River drainage and to the west into the Stones River drainage. Both the Caney Fork and Stones flow north and northwest into the Cumberland River. At 637 m above sea level, Short Mountain is the highest point in the aforementioned peninsula; other hills average 300 to 350 m with slopes of 30 to 60%.
Collections made in several high gradient seepfed creeks in nearby Eastern Highland Rim sites north, south, and east of the above described peninsula failed to record the presence of C. clivosus , new species ( Fig. 4View FIGURE 4). Additionally, a search of the over 4000 lots of Tennessee crayfishes held at the National Museum of Natural History and the Illinois Natural History Survey Crustacean Collection did not produce additional specimens of C. clivosus , new species. While it is highly likely that additional locations for C. clivosus , new species will be found in the elevated peninsula in Cannon and De Kalb counties described above, it is unknown if the species will be found in other regions of central Tennessee or the Eastern Highland Rim. Additional collecting efforts are needed in the Caney Fork River drainage both north and east of the currently known range of C. clivosus , new species to determine if this species is restricted to Cannon and De Kalb counties.
A total of 68 specimens has been examined from five locations in the Caney Fork River drainage (sites 1, 3–6) and one site in the East Fork Stones River drainage (Site 2) in Tennessee. Specific locations are as follows: Cannon Co.: 1) seepfed tributary to Turkey Branch approx. 4.8 km NE Pleasant Ridge, 35.8929°N, 86.0167°W NAD 83, 11 December 2004 (INHS 10234 1 F, 3 juv. F); 2) seepfed tributary to East Fork Stones River approx. 1.6 km SW town of Short Mountain, 35.8473°N, 85.9534°W NAD 83, 28 September 2005 (INHS 10232 morphotype), (USNM 1083161 – paratypes 1 M1, 1 M2, 1 F), (INHS 10233 – 3 MI, 3 MII, 7 F, 1 juv. M, 2 juv. F); 3) seepfed tributary to Connell Creek at end of Tate Road, 4.8 km NE Pleasant Ridge, 35.8941°N, 86.0215°W NAD 83, 6 March 2005 ( INHS 10226 –2View Materials MII, 1 juv. M, 2 juv. F) , 7 April 2005 ( INHS 10224 – 5View Materials MII, 8 F, 2 juv. M, 2 juv. F), 20 August 2005 (INHS 10227 –3 MI, 3 F); 4) seepfed tributary to Wilmouth Creek on N side of Short Mountain, 35.8750°N, 85.9741°W NAD 83, 12 June 2005 ( INHS 10229 – 2View Materials juv. F); DeKalb Co.: 5) seepfed tributary to Dry Creek approx. 4.0 km W Snows Hill, 35.9848°N, 85.9126°W NAD 83, 12 June 2005 (INHS 10230 – 1 MII, 1 F, 1 juv. M); 6) Type locality, tributary of Dry Creek at Pea Ridge Wildlife Management Area, approx. 11.5 km WSW Smithville, 35.9205°N, 85.9271°W NAD 83, 27 September 2005 ( INHS 10235View Materials – holotype), ( INHS 10236View Materials – allotype), ( INHS 10237View Materials – paratypes 1 MI, 1 F)GoogleMaps , ( INHS 10238 – 1View Materials MI, 2 F, 3 juv. M) .
Etymology.— clivosus L. = hilly, steep; in reference to the high gradient, hillside habitat in which the species is found.
Habitat and lifehistory notes.— Cambarus clivosus , new species, occurs in small, highgradient, seepfed creeks with substrates of chert gravel, limestones, and shales ( Fig. 1View FIGURE 1). Creek widths at sites containing the species ranged from 0.25 to 0.6 m and water depths were less than 5.0 cm. At several sites, water alternated between surface and subsurface flow regimes in given reaches. In creeks harboring the species, individuals were encountered under flat pieces of gravel or shale or in burrows. The species was found in two types of burrows, either shallow (> 5 cm) burrows under midchannel shale or gravel or in deep (0.1 – 0.5 m), winding burrows dug into creek banks. The latter burrow type usually migrated horizontally more than vertically amongst subsurface rocks and boulders. Given the small number of collections available, determining definitive lifehistory aspects is difficult. The species has been collected in the months of March, April, June, August, September, and December. Of those collections, form I males were found in August and September. No ovigerous females have been collected or observed. The presence of juveniles with carapace lengths of 5 to 9 mm in September collections suggest that young C. clivosus hatch in summer months. Form I males collected in September were usually found under rocks in midchannel rather than in stream bank burrows while in spring months most males were found in burrows. Fall breeding is not uncommon in burrowing crayfish species and the observations may be a mateseeking behavior by males attempting to locate females sequestered in burrows.
Crayfish associates.—The following species were collected from the same seepfed creeks containing C. clivosus , new species: Cambarus (Erebicambarus) tenebrosus Hay, 1902 and Cambarus (Jugicambarus) friaufi Hobbs, 1953 . At one site, small C. friaufi were found in the same burrows as C. clivosus . In those cases young C. friaufi individuals were found within the first 10 cm of the burrow while the C. clivosus were found in the deeper portions.
Variation.—Several ontogenetic variations are observed in C. clivosus , new species, one of which shows a geographic pattern of distribution. Specimens collected from the East Fork Stones River drainage have a slightly narrower areola, averaging 9.6 times as long as wide compared to areolae of individuals from the Caney Fork drainage which average 8.1 times as long as wide. Other random ontogenetic variations include the degree of excavation of the rostrum, the shape of the antennal scale, and the tubercle pattern on the mesial margin of the palm of the chela. In most individuals the rostrum is moderately excavated while a few specimens had more deeply excavated rostrums. The antennal scale shape is variable in respect to the distal edge. In some individuals that edge is nearly perpendicular to the lateral margin (Fig. 2F) while in others it is angled proximally (Fig. 2E). Finally, the number of palmar tubercles along the mesial margin is variable, ranging from five to eight. In many cases, the proximalmost two tubercles are fused to form a ridge.
Comparisons.— Cambarus clivosus , new species, differs from all other members of the subgenus Jugicambarus in possessing a unique combination of form I male pleopod, carapace, and chelae characters. Other pigmented members of the subgenus that possess a single row of tubercles along the mesial margin of the palm, a wide areola and nonlaterally compressed carapace, and lack long setae on the dorsal and lateral surfaces of the palm and fingers of the chelae include C. asperimanus Faxon 1914 , C. carolinus ( Erichson 1846) , C. conasaugaensis Hobbs and Hobbs 1962 , C. crinipes Bouchard 1973 , C. distans Rhoades 1944 , C. jezerinaci Thoma 2000 , and C. parvoculus Hobbs and Shoup 1947 . Cambarus clivosus differs from C. asperimanus and C. conasaugaensis by possessing a suborbital angle of approximately 90 degrees (Fig. 2C), both of the latter species lack an angle. Cambarus clivosus differs from C. carolinus and C. crinipes by possessing a subapical notch on the central projection of the form I males (Fig. 2J) and differs from C. parvoculus , C. jezerinaci , and C. distans by possessing a triangular rostrum with margins that strongly converge (Fig. 2A). The rostral margins of C. parvoculus , C. jezerinaci , and C. distans are subparallel and terminate at the base of a welldefined acumen (Fig. 2B). The triangular shape of the rostrum in C. clivosus also helps distinguish it from C. crinipes and C. asperimanus . The rostral margins of both of the latter species are subparallel. Cambarus clivosus differs from the newly described C. (J.) tuckasegee Cooper and Schofield in lacking the second row of two to four weak tubercles found along the mesial margin of the palm of the chela.
Relationships.—Following Hobbs’ (1969) use of chelae morphology as the primary character for assessing evolutionary relationships within the genus Cambarus , we assign C. clivosus , new species, to the subgenus Jugicambarus . Members of that subgenus possess subrectangular chelae with a cristiform or serrate row of turbercles along the mesial margins of the palm ( Hobbs 1969; Bouchard 1973), both characters found in C. clivosus . While their rostral shapes differ, Cambarus clivosus shares a central projection with a subapical notch and a suborbital angle with C. parvoculus , C. jezerinaci , and C. distans . However, given that C. parvoculus and C. jezerinaci both possess a strongly recurved central projection and occur in the same type of habitat as C. clivosus , it seems logical to conclude that these three species most likely share a recent common ancestor. Cambarus parvoculus occurs in the Appalachian Uplands of eastern Kentucky and Tennessee and extreme northwestern Geogia ( Taylor and Schuster 2004) while C. jezerinaci is currently known from a restricted portion of the Appalachian Uplands in the Tennessee / Virginia border area ( Thoma 2000). Given the paucity of informative morphological characters and molecular datasets, the monophyly of the subgenus Jugicambarus and interrelationships of its members have never been rigorously analyzed using cladistic techniques. Future analyses using a combined data set of both molecular and morphological characters should help elucidate the relationships within the subgenus and help resolve the phylogenetic position of C. clivosus .
Suggested vernacular name.—Short Mountain Crayfish, in reference to the geographic feature near which the species is found.
We are grateful to M. Retzer for reviewing an earlier version of this manuscript. We are also grateful to D. Withers, R. McCoy, and H. Garland for assisting with sampling locality access and permitting and to R. Lemaitre and K. Reed for graciously providing records from and access to the crustacean collections at the National Museum of Natural History, Smithsonian Institution.
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