Fallicambarus (Creaserinus) caesius Hobbs 1975

Fallicambarus (Creaserinus) caesius

DIAGNOSIS.—Ventral surface of propodus of chela with longitudinal row of stiff setae near lateral margin; merus of cheliped with conspicuous ventrolateral row of setae largely or completely replacing ventrolateral row of tubercles; mesial ramus of uropod without distolateral spine; first pleopod of first form male with distal half of shaft inclined caudally, and central projection not extending so far caudally as mesial process; abdomen of male conspicuously narrower than cephalothorax; boss on coxa of fourth pereiopod of male directed caudomesially; annulus ventralis with width and length subequal and not obscuring sclerite immediately caudal to annulus.

HOLOTYPIC MALE, FORM I.—Cephalothorax subovate, compressed (Figure 7a,l). Abdomen much narrower than thorax (9.5 and 14.2 mm); greatest width of carapace greater than depth at caudodorsal margin of cervical groove (14.2 and 13.5 mm). Areola obliterated along much of its length; length 39.7 percent of entire length of carapace (44.5 percent of postorbital carapace length). Rostrum with convergent, slightly thickened margins rather suddenly contracted to form broad, short, indistinctly delimited acumen; upturned tip leaching midlength of penultimate podomere of antennular peduncle; dorsal surface of rostrum concave cephalically but subplane caudally with prominent subtransversely arranged punctations as well as submarginal row. Subrostral ridges strong and evident in dorsal aspect along basal third of rostrum. Postorbital ridges prominent and grooved laterally. Suborbital angle and branchiostegal and cervical spines absent. Carapace punctate dorsally, branchiostegites granulate laterally and with sublinear group of granulations ventral to cephalic portion of cervical groove; short, oblique, accessory groove joining depressed area on branchiostegite to cervical groove (Figure 7a); other grooves and depressions as illustrated.

Abdomen much shorter than carapace (25.3 and 30.5 mm); pleura (Figure 7m) very short and broadly rounded; cephalic lobe of pleuron of second segment not overlapping reduced pleuron of first. Telson not clearly divided into cephalic and caudal sections (Figure 7h): dextral margin with single short fixed spine distal to midlength, corresponding position on sinistral margin not produced; entire dorsal surface of telson and uropods with short stiff setae. Proximal podomere of uropod (Figure 7h) without spines. Both rami rounded (right uropod partially regenerated) distally, lateral ramus with one very small fixed lateral spine and longer articulated one mesial to it; mesial ramus lacking lateral spine and median distal spine premarginal; submedian longitudinal ribs prominent on both rami.

Cephalomedian lobe of epistome (Figure 7d) subpentagonal, with margins elevated and arched groove at base; main body with prominent cephalomedian fovea and paired prominent pits on cephalic side of arched epistomal zygoma, lateral extremities with small tubercles. Ventral surface of proximal podomere of antennule without spine. Antennal peduncle lacking spines, flagellum almost reaching caudodorsal margin of carapace. Antennal scale (Figure 7k) about 2.2 times longer than broad, broadest slightly distal to midlength, evenly rounded mesially, lateral margin arched and bearing row of punctations; distolateral spine heavy, short, and reaching midlength of penultimate podomere of antennular peduncle. Ventral surface of ischium of third maxilliped (Figure 7j) with submedian row of stiff setae, lateral submarginal one consisting of shorter setae, and scattered clusters situated between submedian row and teeth on mesial margin.

Right chela (Figure 7q) about 1.8 times longer than broad, strongly depressed; mesial margin of palm with row of 6 tubercles subtended dorsally by row of 5 smaller ones, and ventrally by 4 much smaller ones (left chela with 6, 5, and 3 respectively); dorsal surface of palm with scattered punctations, most prominent ones at base of fixed finger; ventral surface with arched sublateral row of punctations (Figure 7p) bearing tufts of long stiff setae, other setae scattered over surface; distal ridge, opposite base of dactyl, with subacute tubercle and much smaller tubercle proximal to it. Opposable margin of fixed finger with row of 4 tubercles, second from base largest, along proximal two-thirds of finger; single row of minute denticles distally and conspicuous tuft of setae proximally; lateral surface strongly costate with row of setiferous punctations; dorsal and ventral surfaces with prominent submedian ridge flanked by punctations, dorsal surface also with shorter submedian ridge flanking tubercles on opposable margin. Opposable margin of dactyl with row of 3 tubercles (4 on left), second from base largest and marking distal extremity of conspicuous incision, row of minute denticles present distally; mesial margin tuberculate along proximal third and with row of setiferous punctations extending distally; dorsal and ventral surfaces with submedian ridge flanked by setiferous punctations, and dorsal surface with shorter ridge flanking row of tubercles on opposable margin.

Carpus (podomere tilted mesially in Figure 7q) of cheliped with prominent submedian longitudinal furrow dorsally, latter flanked mesially by scattered tubercles and punctations and laterally by punctations; mesial surface with prominent spikelike tubercle distally and number of smaller ones both proximal and ventral to it; ventral surface smooth except for 2 tubercles on distal margin, one forming articular knob, other mesial to it; lateral surface punctate with single small tubercle on distal margin immediately dorsal to ventrolateral articular knob. Merus with dorsodistal surface bearing small tubercles and punctations; ventral surface with ventromesial row of 11 tubercles, and row of setiferous punctations replacing usual ventrolateral row; otherwise podomere smooth or weakly punctate. Basioischial podomere with single tubercle slightly distal to fracture suture; sufflamen well developed.

Chela of second pereiopod with row of long setae on both margins of palm, and on dorsal and ventral margins of carpus; distal half of ventral surface of merus with similar row of setae.

Ischium of third pereiopod with simple curved hook not reaching basioischial articulation (Figure 7g) and not opposed by tubercle on basis. Coxa of fourth pereiopod with rather weak caudomesially directed boss. Coxa of fifth pereiopod lacking caudomesial boss but with setiferous ventral membrane.

First pleopod (Figure 7b,f,o) reaching coxa of third pereiopod, situated deep within sternum, and obscured, particularly distally, by setae extending caudally and mesially from ventral margin of sternum; proximomesial spur lacking; distal half of shaft inclined caudally; terminal elements consisting of corneous, broad, subterminally notched central projection; mesial process subacute, twisted, appearing subspatulate in caudal aspect, and extending beyond tip of central projection; cephalic process absent.

ALLOTYPIC FEMALE.—Excluding secondary sexual characters, differing from holotype in following respects: abdomen only slightly narrower and distinctly longer than thorax; cephalic lobe of pleuron of second abdominal segment overlapping pleuron of first (Figure 7n); cephalic section of telson with 2 spines in each caudolateral corner, mesial pair articulated; antennae reaching slightly caudal to midlength of areola; right chela with mesial margin of palm bearing row of 6 tubercles subtended by 2 ventrally and row of 3 or 4 dorsally (left chela with 3, 5, and 3, respectively); ventral surface of palm of right chela with 3 small tubercles proximal to marginal tubercle at base of dactyl; opposable margin of dactyl of chela with row of 5 tubercles (6 on left chela), third from base largest; carpus of chela with several members of cluster of tubercles on mesial surface larger and more acute than those in holotype; 12 tubercles in ventromesial row on merus of left cheliped.

Annulus ventralis (Figure 7i) subequal in length and width, deeply embedded in sternum and firmly fused to it cephalically; caudal portion slightly hinged to cephalic weakly sclerotized area, latter bearing broad median depression; caudal heavily sclerotized portion forming U-shaped, ventrally elevated prominence; sinus originating in caudodextral region of cephalic depression and forming tilted S-shaped furrow across elevated prominence, ending slightly sinistral to median line; tongue short and directed caudodextrally with fossa along its caudodextral margin. Sclerite immediately caudal to annulus strongly arched ventrally, broader than long and almost one-third as long as annulus; surface without punctations or tubercles. First pleopod reaching almost to midlength of annulus when abdomen flexed.

MORPHOTYPIC MALE, FORM II.—Differing from holotype in following respects: cephalic lobe of pleuron of second abdominal segment overlapping pleuron of first; telson more distinctly divided into cephalic and caudal sections, caudodextral angle of cephalic section with single fixed spine, caudosinistral with 2 spines as in allotype; mesial margin of palm of right chela with row of 6 tubercles subtended ventrally by 1 and dorsally by row of 4 (left chela with 6, 1, and 3, respectively); opposable margin of dactyl of chela with row of 5 tubercles; carpus of left cheliped without prominent tubercle on mesial surface; merus with single tubercle situated lateral to ventrolateral row of setae at about midlength of podomere; hook on ischium of third pereiopod and boss on coxa of fourth less prominent than in holotype. First pleopod (Figure 7c,e) with distal half not so clearly inclined caudally; central projection noncorneous, not so strongly compressed, and with only vestige of subapical notch; mesial process much more inflated than in holotype and contiguous to, or overlapping, central projection along entire length of latter.

COLOR

Fallicambarus (Creaserinus) caesius Hobbs

Fallicambarus (Creaserinus) caesius Hobbs, 1975:24, fig. 7.

Fallicambarus caesius.—Hobbs, 1975:28.

TYPES.—Holotype, allotype, and morphotype, USNM 144921, 144922, 144923 (male I, female, male II); paratypes, USNM.

TYPE LOCALITY.—Roadside ditch at Hot Spring-Saline county line, Arkansas, on State Route 67.

RANGE.—Basins of Ouachita River and Dorcheat Bayou in southern Arkansas.

HABITAT.—Burrows.