Orconectes forceps

Orconectes (Procericambarus) forceps (Faxon)

Cambarus forceps Faxon, 1884:133; 1885a:119, pl. 5: fig. 4, pl. 9: figs. 5, 5′, 5a, 5a′.

Cambarus (Faxonius) forceps.—Ortmann, 1905c: 112.

Cambarus rusticus forceps.—Ortmann, 1931:66.

Cambarus (Faxonius) rusticus forceps.—Ortmann, 1931:72.

Faxonius forceps.—Creaser, 1933a:3 [by implication]; 1962:2 [by implication].

Faxonius (Faxonius) forceps.—Creaser, 1933b:10 [by implication].

Orconectes rusticus forceps.—Hobbs, 1942a:352 [by implication].—Fitzpatrick, 1963:61 [by implication].

Orconectes (Orconectes) rusticus forceps.—Hobbs, 1942b:154 [by implication].

Orconectes forceps.—Fitzpatrick, 1967a: 143.—Hobbs, 1972b:98. figs. 77i, 80d; 1974b:29, fig. 137; 1981:289, figs. 19c, 107b, 108c, 112, 113, 232.

Orconectes (Procericambarus) forceps.—Fitzpatrick, 1987a:58, fig. 9.

TYPES.—Syntypes, USNM 4880 (3 male I, 4 female), MCZ 3582 (male I, female).

TYPE LOCALITY.—Cypress Creek, Lauderdale County, Alabama.

RANGE.—Tennessee River drainage, chiefly above Walden Ridge, from southwestern Virginia to Wayne County, Tennessee.

HABITAT.—Streams.

Orconectes forceps (Faxon)

Cambarus forceps Faxon, 1884:133; 1885a:119–121, 163, 168, 170, 174, 178, pl. V: fig. 4, pl. IX: fig. 5, 5', 5a, 5a'.

Cambarus (Faxonius) forceps.—Ortmann, 1905a:109, 112, 115, 116, 128.

Cambarus (Faxonius) rusticus forceps.—Ortmann, 1931:66, 71–76, 78, 79, 81.

Faxonius forceps.—Creaser, 1933a:3 [by implication].

Faxonius (Faxonius) forceps.—Creaser, 1933b:10 [by implication].

Orconectes rusticus forceps.—Hobbs, 1942a:352 [by implication]; 1968b:K–13*, K–30, fig. 28d.—Anonymous, 1970c:50*, 52*.—Wharton, 1978:220*.

Orconectes (Orconectes) rusticus forceps.—Hobbs, 1942b:154 [by implication].

Orconectes forceps.—Fitzpatrick, 1967:143.—Hobbs, 1972b:98. 148*, figs. 77i, 80d; 1974b:29, fig. 137.—Bouchard. 1976a:563, 574–576, 579, 581.

The list of references cited above is by no means a complete bibliography for the species but does include all of the synonyms, summary articles, records of the occurrence of the species in Georgia (indicated by asterisks), and illustrations.

SUMMARY OF LITERATURE PERTAINING TO GEORGIA.—Although this crayfish was described in 1884, not until 1959 is there evidence that it was collected in Georgia. The only published localities (see below) recorded from the state appeared in 1970 in an anonymous report of a “Biological Investigation of Tennessee Basin Streams of Northwestern Georgia.”

DIAGNOSIS.—Rostrum with margins slightly or strongly concave laterally and bearing marginal spines or tubercles. Postorbital ridges terminating cephalically in spines or tubercles. Cervical spine well developed. Areola 2.8 to 4.4 (average 3.7) times as long as broad and constituting 30.8 to 34.9 (average 32.3) percent of entire length of carapace (40.4 to 43.4, average 41.9, percent of postorbital carapace length). Mesial surface of palm of chela shorter than dactyl and bearing at least 2 rows of tubercles, mesialmost consisting of 7 to 10, dorsal surface conspicuusly punctate; opposable margin of fingers strongly gaping, especially in larger individuals, and bearing row of rounded tubercles along proximal three-fourths and single row (sometimes staggered in males) of minute denticles along distal fourth; prominent tufts of setae often present at mesial base of fixed finger (usually absent in large males). Ventral surface of carpus of cheliped lacking distomedian spine or tubercle. Ischium of third pereiopod of first form male with hook overreaching basioischial articulation but not opposed by tubercle on basis. First pleopod of male reaching coxa of second pereiopod and with mesial process slightly shorter than central projection; former bowed with distal extremities often overlapping; central projections, constituting less than 0.5 length of appendages, subparallel and contiguous along most of length, distal parts not conspicuously deflected laterally; cephalic surface of appendage lacking shoulder at base of central projection. Female with annulus ventralis bearing deep transverse fossa across midlength; first pleopod present.

COLOR NOTES (Figure 108c).—Basic coloration tan to straw with dark brown to black markings. Cephalic section of carapace with rostral margins and postorbital ridges dark brown; trilobed splotch covering much of mandibular adductor and midcaudal gastric area, and irregular horizontal dark line extending from ventral part of trilobed splotch to orbit; remainder of cephalic section with smaller dark markings, especially on rostrum and anterior part of gastric region. Thoracic section of carapace with conspicuous saddle caudally; horns extending anteriorly almost to level of midlength of areola, sometimes also with prominent irregular markings, subparallel to horns of saddle, situated more anteriorly on branchiostegites; areola with dark lines along branchiocardiac grooves converging anteriorly to apex, latter located on median line just posterior to cervical groove. Cephalic part of first abdominal tergum black, succeeding 4 with paired, dark, anteriorly situated dorsolateral splotches decreasing in size and intensity on more posterior terga; caudal parts of third, fourth, and fifth terga with paired, narrow transverse bars; sixth tergum with small dark flecks. First pleuron with large cream spot, second through sixth slightly darker than corresponding terga, sometimes set off from latter basally by undulating dark line. Cephalic section of telson with median dark patch flanked by lateral ones; caudal section with irregular flecks; lateral halves of both rami of uropods and caudal section of mesial ramus darker than remainder. Antennular and antennal peduncles mostly dark brown but distal podomere of latter pale dorsally; flagella reddish brown; antennal scale dark laterally and almost cream dorsolaterally, lamellar area dark laterally, fading mesially. Chelipeds with distal third of merus often almost black dorsally; carpus with conspicuous dark patch mesially and with similarly colored splotches dorsally; palmar area of propodus with dark mesial margin, irregular and anastomosing splotches dorsally, and with black wash at base of fixed finger; both fingers dark but becoming pale pinkish cream along distal third. Remaining pereiopods mottled from ischium distally. Ventral surface of body bluish cream.

In some individuals conspicuous dark markings on carapace greatly reduced in intensity and size.

TYPES.—Syntypes, USNM 4880 (3I, 4), MCZ 3582 (I, ).

TYPE–LOCALITY.—Cypress Creek, Lauderdale County, Alabama.

RANGE.—Tennessee River drainage from southwestern Virginia downstream to Wayne County, Tennessee. In Georgia, it has been found only in the Ridge and Valley Province, where it occurs in the South Chickamauga Creek Basin in Catoosa County.

GEORGIA SPECIMENS EXAMINED.—I have examined 38 specimens from the following localities. Catoosa County: (1) South Chickamauga Creek at Rte S819 in Graysville (Anonymous, 1970c:52), 3II, 2, 2j, 30 Aug 1959, W. R. Taylor, R. H. Kanazawa, collectors; 3II, 2, 4j, 8j, 26 Aug 1969, E. T. Hall, Jr., M. W. Walker; (2) Little Chickamauga Creek just above confluence with South Chickamauga Creek near St Rte 2 at Ringgold (Anonymous, 1970c:50), 1I, 1II, 2, 1j, 3j, 26 Aug 1969, ETH, MWW; (3) South Chickamauga Creek at Rte S280, Ringgold, 5I, 1, 23 Oct 1977, R. W. Bouchard, J. W. Bouchard.

VARIATIONS.—So few specimens are available from Georgia that the variations noted probably do not adequately represent those actually existing. There is remarkable uniformity in most features. As noted in the “Diagnosis,” however, the areola is rather variable in width, and the number of punctations across the narrowest part ranges from five to seven. The number of tubercles in the mesialmost row on the mesial surface of the palm of the chela ranges from seven to 10, that on the opposable margin of the fixed finger seven to nine, and on the corresponding surface of the dactyl nine to 11. The carpus of the cheliped always bears one large tubercle and usually there is a spiniform tubercle situated dorsomesially, which in larger specimens is sometimes reduced to a rudiment; rarely a small tubercle is present proximal to the major one. The dorsodistal surface of the merus is always provided with one spiniform tubercle, and occasionally there are two of them; the mesial and lateral rows of tubercles on the ventral surface that are characteristic of many crayfishes are usually each represented by a single, occasionally two, strong distal spine; the more proximal members of the two series, if present at all, are exceedingly small. Usually a small tubercle is present on the mesial surface of the ischium adjacent to the basioischial suture, but it is sometimes absent. The annulus ventralis varies chiefly in the breadth and depth of the transverse fossa and the relative height of its anterior wall.

SIZE.—The largest specimen available is a female in which the length of the carapace is 25.5 (postorbital carapace length 20.5) mm. The largest and smallest first form males have corresponding lengths of 24.8 (19.4) and 18.9 (14.2) mm, respectively. No ovigerous females or ones carrying young have been collected in Georgia.

Orconectes forceps (Faxon)

Cambarus forceps Faxon, 1884:133; 1885a:119, pl. 5: fig. 4; pl. 9: figs. 5, 5′, 5a, 5a′.

Cambarus (Faxonius) forceps.—Ortmann, 1905c: 112.

Cambarus (Faxonius) rusticus forceps.—Ortmann, 1931:72.

Faxonius forceps.—Creaser, 1933a:3 [by implication]; 1962:2 [by implication].

Faxonius (Faxonius) forceps.—Creaser, 1933b: 10 [by implication].

Orconectes rusticus forceps.—Hobbs, 1942a:352 [by implication].—Fitzpatrick, 1963:61 [by implication].

Orconectes (Orconectes) rusticus forceps.—Hobbs, 1942b: 154 [by implication].

Orconectes forceps.—Fitzpatrick, 1967a: 143.—Hobbs, 1972b: 98, figs. 77i, 80d.

TYPES.—Syntypes, USNM 4880 (3 I, 4 ), MCZ 3582 (I, ).

TYPE-LOCALITY.—Cypress Creek, Lauderdale County, Alabama.

RANGE.—Tennessee River drainage, chiefly above Walden Gorge, from northern Alabama to southwestern Virginia.

HABITAT.—Streams.

Orconectes forceps eller «Surgeon crayfish» er en art av ferskvannskreps innenfor slekten Orconectes (familie Cambaridae, orden Reptantia) som inngår i den store gruppen av såkalte tifotkreps. Dette er ferskvannskreps som på engelsk oftest kalles «crayfish».

Orconectes forceps er en av de om lag 85 artene i slekten, og har en utbredelse med forekomster i elver og innsjøer nesten utelukkende i Alabama, Georgia, Virginia og Tennessee.