Little Tennessee River Crayfish

Cambarus (Puncticambarus) georgiae

Cambarus (Puncticambarus) sp.—Anonymous, 1973e:2*.

The only previous record of this crayfish is based on my determination of specimens from Rabun County, Georgia, and Macon County, North Carolina. Based on information obtained from me, it was noted by Anonymous (1973e) as being rare in North Carolina.

DIAGNOSIS.—Body pigmented, eyes well developed. Rostrum with marginal spines or tubercles. Areola 2.3 to 3.2 times as long as broad and constituting 30.7 to 35.6 percent of total length of carapace (40.7 to 44.8 percent of postorbital carapace length) with 8 to 10 punctations across narrowest part. Cervical and branchiostegal spines well developed; hepatic spines absent; suborbital angle usually strong and acute; postorbital ridges with acute spines or tubercles. Antennal scale approximately 2.5 times as long as wide, broadest at about midlength. Chela with single well-defined row of 8 to 10 tubercles on mesial surface of palm, occasionally with few in second poorly defined row immediately dorsal to mesial row; lateral margin of chela costate; lacking conspicuous impression dorsally and ventrally at base of fixed finger; dactyl less than twice length of mesial margin of palm. Hook on ischium of third pereiopod of first form male overreaching basioischial articulation and usually opposed by tubercle on basis. First pleopod of first form male with central projection bearing subapical notch, recurved at angle of about 106 degrees; mesial process inflated with undulating, distal lobe, and directed caudolaterally at angle slightly greater than 90 degrees. Female with annulus ventralis shallowly embedded in sternum and somewhat asymmetrical; first pleopod present. Carapace and abdomen mottled, latter with linear series of oblique dark splotches dorsolaterally and on pleura.

HOLOTYPIC MALE, FORM I.—Body subovate, compressed (Figure 96a,j). Abdomen narrower than cephalothorax (11.6 and 13.2 mm); maximum width of carapace greater than depth at caudodorsal margin of cervical groove (13.2 and 10.7 mm). Areola 2.3 times as long as broad, with 9 punctations across narrowest part, punctations small and somewhat crowded; length 33.2 percent of total length of carapace (43.2 percent of postorbital carapace length). Rostrum with slightly convergent, weakly thickened margins bearing acute marginal spines; acumen moderately long, curved dorsally, and reaching midlength of ultimate podomere of antennular peduncle; upper surface of rostrum concave with numerous closely set punctations. Subrostral ridge weak and evident in dorsal aspect only along basal portion of rostrum. Postorbital ridge comparatively short, not strongly elevated, grooved dorsolaterally and bearing acute spine cephalically. Suborbital angle and branchiostegal spine strong and acute. Cervical spine moderately well developed and flanked dorsally by large tubercle. Carapace punctate dorsally and with very fine granulations laterally.

Abdomen longer than carapace (29.4 and 25.6 mm); pleura of moderate length, somewhat truncate ventrally and subangular caudoventrally. Cephalic section of telson with 2 spines in each caudolateral corner. Proximal podomere of uropod with distal spine on each lobe; mesial ramus of uropod with weak submedian ridge terminating in short premarginal spine.

Cephalomedian lobe of epistome (Figure 96i) subtriangular, with cephalolateral margins somewhat thickened and undulating; main body with prominent median fovea; epistomal zygoma strongly arched. Ventral surface of proximal podomere of antennule with spine at base of distal third. Antennal peduncle with spine on lateral surface of basis and ventral surface of ischium; flagellum broken in holotype but reaching sixth abdominal tergum in other specimens; antennal scale (Figure 96g) about 2.5 times as long as broad, broadest near midlength, its mesial margin evenly rounded, and distal spine reaching level of apex of acumen. Ventral surface of ischium of third maxilliped studded with clusters of long stiff setae on mesial half and with submarginal lateral row of much smaller ones; distolateral extremity subangular.

Right chela (Figure 96l) about twice as long as broad and mesial margin of palm constituting about one-third total length. Mesial margin of palm with row of 8 tubercles, excluding articular prominences, palm otherwise punctate. Both fingers with moderately prominent submedian longitudinal ridges dorsally and ventrally, flanked by setiferous punctations. Fixed finger costate laterally, with costa extending proximally onto palm, lacking tubercles except for row of 4 large, rounded ones on basal two-fifths of opposable margin and single subacute one on lower level of opposable surface at base of distal two-fifths; narrow band of minute denticles extending distally from row of tubercles to base of corneous tip of finger. Opposable margin of dactyl with row of 6 rounded tubercles along proximal half, followed distally by narrow band of minute denticles; mesial surface of finger with few low tubercles basally, giving way to row of setiferous punctations.

Carpus of cheliped with shallow oblique furrow and scattered punctations dorsally; mesial surface bearing single prominent acute spine; ventral surface provided with 2 marginal spines, 1 on articular prominence and other submedian; and lateral surface punctate. Merus with prominent spine and large tubercle on distal part of dorsal surface, mesial and lateral surfaces punctate; ventral surface with lateral row of 3 prominent spines and mesial one of 8 tubercles, most of which spiniform. Ventromesial margin of ischium with row of 3 tubercles.

Ischium of third pereiopod with simple hook extending proximally over basioischial articulation (Figure 96h), hook opposed by small tubercle on basis. Coxa of fourth pereiopod with obliquely, vertically disposed caudomesial boss; that of fifth pereiopod lacking boss, ventral membrane with few scattered setae.

First pleopods (Figure 96b,d,f) with gap between bases and reaching coxae of third pereiopods, both terminal elements recurved at angle slightly greater than 90 degrees to main shaft of appendage. Mesial process somewhat inflated, although biconcave basally and terminating in caudolaterally directed, undulating lobe reaching level of apex of central projection. Latter with well-defined subapical notch.

ALLOTYPIC FEMALE.—Differing from holotype, other than in secondary sexual characters, as follows: margins of rostrum thicker and more strongly convergent; suborbital angle broadly rounded, virtually obsolete; lacking accessory tubercles immediately dorsal to cervical spine; cephalic section of telson with single spine in each caudolateral corner; mesial margin of palm of chela with row of 6 or 7 tubercles flanked by 1 or 2 squamous ones dorsally; opposable margin of fixed finger of chela with row of 5 tubercles and that of right with 2 on lower level; opposable margin of dactyl with row of 4 tubercles; dorsal surface of merus with only 1 spine, ventral surface with lateral row of 2 or 3 spines and mesial row of 7, mostly very weak, tubercles; basal opposable portions of both fingers with more conspicuously long setae than in holotype. (See “Measurements.”)

Annulus ventralis (Figure 96k) about twice as broad as long; situated rather shallowly in sternum; elevated (ventrally) cephalic area traversed by submedian longitudinal furrow; sinus originating in caudal extremity of furrow, somewhat anterior to midlength of annulus, extending dextrally, forming hairpin curve and returning to median line, there extending caudally in low dextral arc, cutting caudal margin of annulus; prominent tongue directed dextrally and disappearing in fossa beneath dextral wall. Postannular sclerite subspindle shaped and about one-half as wide as annulus. First pleopod reaching cephalic margin of annulus when abdomen flexed.

MORPHOTYPIC MALE, FORM II.—Differing from holotype in following respects: marginal spines on rostrum stronger and more divergent; lacking accessory tubercles immediately dorsal to cervical spine; merus of right cheliped with only 2 spines ventrolaterally, and setae at base of fingers more conspicuous. Hook on ischium of third pereiopod very small but opposed by tubercle on basis; boss on coxa of fourth pereiopod much reduced. (See “Measurements.”) First pleopod (Figure 96c, e) differing from that of holotype chiefly in bulbous nature of terminal elements, both shorter, and central projection much broader with only hint of subapical notch.

COLOR NOTES (Figure 89d).—As in many epigean crayfishes, the color pattern occurs in two phases, one in which a black pattern appears on a greenish or bluish gray background, and the other with very dark brown on a tan or orange tan background. The former phase is described here.

Ground color of carapace and abdomen greenish gray. Rostrum with black margins and white-tipped marginal spines; gastric region with pair of laterally convex markings lying between postorbital ridges, each joined by narrow, dark longitudinal line to dark gray splotch near midlength of cephalic region, and caudal gastric region with pair of black angular bars immediately cephalic to cervical groove. Paired black crescents flanking caudal parts of postorbital ridges, with cephaloventral extensions on hepatic region. Black band following cervical groove, with caudally directed triangular thickening on middorsal line, and interrupted laterally by white cervical spine just before fading and merging with light gray color of lower hepatic area. Short, oblique black bar extending from base of postorbital spine caudoventrally, bar flanked cephaloventrally and caudodorsally by narrow subparallel white bands. Areola dark gray, sometimes with black splotches. Branchiostegites with paired, irregular, broad, black longitudinal stripes dorsolaterally (stripes bearing irregular gray and white splotches), joined by narrow transverse band on caudal margin of carapace. Abdomen with terga of 5 anterior segments bearing small median gray to black spot; that on fifth joining horizontal band across caudal margin of segment, there radiating caudally on tergum of sixth segment in median longitudinal stripe and pair of caudally divergent ones. Bases of pleura with paired L-shaped black markings, apex of angle directed caudoventrally; in addition, paired, short, oblique bars situated more ventrally, and caudoventral marginal ones also present. Telson with basal, dark gray, median patch flanked by paired, black, narrow horizontal bars near cephalic margin and with paired, black longitudinal stripes on lateral margins of cephalic section. Mesial ramus of uropod with dark gray submedian stripe and black stripe on lateral margin. Antennal scale mostly white, with black lateral margin and longitudinal stripe along lateral margin of lamellar area. Cheliped pale gray basally, becoming dark gray on distal part of merus, latter with spines on dorsal surface white; carpus mostly gray with proximolateral black spot and very dark gray splotches mesio- and laterodistally; chela with gray palm dorsally, becoming dark gray toward fingers, both of latter dark gray with preapical reddish band fading to white at tip of fingers.

Measurements (mm)

TYPES.—The holotypic male, form I, allotypic female, and morphotypic male, form II (numbers 118944, 144954, 144955, respectively), are deposited in the National Museum of Natural History, Smithsonian Institution, along with the paratypes comprising 2I, 14II, 17, 1j, 1j, and 1 ovigerous . Specimens from the third locality listed under “Specimens Examined” are excluded from the type series.

TYPE-LOCALITY.—Little Tennessee River at U.S. Highway 441 south of Dillard, Rabun County, Georgia. At this locality the stream is some three to seven meters wide, a few centimeters to one meter deep, and flows swiftly over a sandy clay bottom of alternating riffles and quieter stretches. Stones occur abundantly at the riffles. Filamentous green algae and a moss are the only aquatic plants observed; along the shore Alnus rugosa, Sambucus sp., and Rubus sp. form dense thickets. Much more abundant than Cambarus (P.) georgiae at this locality is Cambarus (C.) bartonii. (See “Ecological Notes.”)

RANGE.—Known only from the upper Little Tennessee River in Rabun County, Georgia, and Macon County, North Carolina (Blue Ridge Province).

SPECIMENS EXAMINED.—I have examined 51 specimens from the following localities. GEORGIA. Rabun County: (1) type-locality, 1 ovig , 23 Apr 1961, D. C. Scott, collector; 1II, 6 Jun 1961, Richards, Miller, Bane; 1I, 27 Apr 1967, T. Unestam, HHH; 2, 12 Apr 1968, G. B. Hobbs, HHH; 1j, 1j, 29 Nov 1970, T. A. English, Jr., E. T. Hall, Jr.; 1I, 9II, 3, 1 May 1971, TAE, ETH, HHH. NORTH CAROLINA. Macon County: (2) Little Tennessee River 7.0 mi N of Georgia St line on US Hwy 441 and 0.2 mi E on unnumbered road, 1I, 5II, 12, 1 May 1971, TAE, ETH, HHH; (3) Sugar Fork River 8 mi NE of Franklin on US Hwy 64, 2II, 3, 5j, 2j, 26 Jun 1957, E. A. Crawford.

VARIATIONS.—Inasmuch as this crayfish is known from only three localities in the upper Little Tennessee Basin, it is not surprising that variations are so few and of such a minor nature. Those associated with the diagnostic features are accounted for in the “Diagnosis,” and others are mentioned in the brief descriptions of the allotype and morphotype. In addition, the spine on the mesial surface of the carpus of the cheliped may be simple or bispinose; the tubercles along the opposable margin of the dactyl vary from four to seven. The basis of the third pereiopod in the male may lack a tubercle opposing the hook on the ischium; and the coxa of the fifth pereiopod may possess a very small caudomesial tuberculiform boss. The mesial process of the first pleopod may exceed slightly in its caudal extension that of the central projection.

SIZE.—The largest specimen available is a first form male from the North Carolina locality, having a carapace length of 28.9 mm (postorbital length 22.7 mm). The smallest first form male is the holotype, having corresponding measurements of 25.6 and 19.7 mm, respectively. The single ovigerous female has corresponding measurements of 24.6 to 19.4 mm.

Cambarus (Puncticambarus) georgiae Hobbs

Cambarus (Puncticambarus) sp.—Anonymous, 1973b:2.

Cambarus (Puncticambarus) georgiae Hobbs, 1981:251, figs. 21g, 87, 89d, 96, 225.

TYPES.—Holotype, allotype, and morphotype, USNM 118944, 144954, 144955 (male I, female, male II); paratypes, USNM.

TYPE LOCALITY.—Little Tennessee River at U.S. Highway 441, south of Dillard, Rabun County, Georgia.

RANGE.—Known only from the Little Tennessee River in Rabun County, Georgia, and Macon County, North Carolina.

HABITAT.—Streams.

Cambarus georgiae, the Little Tennessee crayfish, is a species of crayfish in the family Cambaridae. It is found in Georgia and North Carolina.

The IUCN conservation status of Cambarus georgiae is "LC", least concern, with no immediate threat to the species' survival. This status was last reviewed in 2010.