Procambarus geminus Hobbs 1975

Procambarus (Ortmannicus) geminus Hobbs

Procambarus (Ortmannicus) geminus Hobbs, 1975:1, fig. 1.

Procambarus geminus.—Bouchard and Robison, 1981:26.

TYPES.—Holotype, allotype, and morphotype, USNM 145756, 145757, 145758 (male I, female, male II); paratypes, BMNH, USNM, H.W. Robison.

TYPE LOCALITY.—“Roadside pool (perhaps a streambed, but no flow was detected), 1.7 miles [2.7 km] south of Taylor, Columbia County, Arkansas, on State Route 132” (Hobbs, 1975:4–5).

RANGE.—Red River Basin in Columbia, Lafayette, and Miller counties, Arkansas, and Webster and Sabine parishes, Louisiana.

HABITAT.—Lentic and sluggish lotic situations.

Procambarus (Ortmannicus) geminus

DIAGNOSIS.—Pigmented, eyes well developed. Rostrum with marginal spines, median carina absent. Carapace with small cervical spine. Areola 6.1 to 12.0 times longer than broad and constituting 30.3 to 33.7 percent of total length of carapace (39.7 to 43.6 percent of postorbital carapace length). Suborbital angle varying from small and acute to obsolete. Postorbital ridge with cephalic spine. Hepatic area without spines. Antennal scale approximately three times longer than wide, broadest proximal to midlength. Ischia of third and fourth pereiopods of first form male with simple hooks, that on third overreaching basioischial articulation and neither opposed by tubercle on basis; coxa of fourth pereiopod with prominent, inflated, vertically disposed caudomesial boss, that of fifth pereiopod with prominent thin, narrow boss caudomesially. First pleopod of first form male reaching coxa of third pereiopod, strongly asymmetrical, although lacking angular shoulder, with prominent rounded bulge on cephalic surface immediately proximal to level of mesial process, and provided with tuft of subapical setae arising from caudal knob; distal portion provided with long, acute mesial process, directed at right angle to main shaft of appendage, and extending much farther caudally than other terminal elements; cephalic process corneous, acute, strongly recurved, hooding central projection, and with apex directed caudally, parallel to central projection and mesial process; central projection corneous, its two components clearly visible laterally, subtriangular and extending caudally slightly beyond tip of cephalic process; caudal clement consisting of slender, corneous caudal process—directed caudodistally subparallel to caudal margin of central projection and reaching almost as far caudally—and caudal knob, studded with subapical setae, situated on caudolateral surface of appendage at base of centrocaudal process (caudal element of central projection). Annulus ventralis about 1.6 times broader than long, symmetrical, with median elevation (ventrally) cut by prominent tilted S-shaped sinus originating in cephalomedian trough and ending sinistral to median line on sinistral prominence much cephalic to caudal margin of annulus. Sternum cephalic to annulus tuberculate and partially overhanging annulus. Postannular plate subspindle shaped, unadorned, slightly more than one-third as long and one-half as wide as annulus. First pleopod present in female.

HOLOTYPIC MALE, FORM I.—Cephalothorax (Figure 1 a,i) subovate, compressed. Abdomen narrower than thorax (16.8 and 21.6 mm). Greatest width subequal to height of carapace at caudodorsal margin of cervical groove. Areola 8.6 times longer than wide with 3 punctations across narrowest part. Cephalic section of carapace about 2.2 times as long as areola, length of latter 31.6 percent of entire length of carapace (42.2 percent of post-orbital carapace length). Surface of carapace rather densely punctate dorsally, heavily granulate on lateral portions of branchiostegites and over attachment of mandibular muscle; most of hepatic region polished or sparsely punctate. Rostrum broad basally. with strongly convergent margins subparallel for short distance at base, bearing small marginal spines at level of midlength of penultimate podomere of antennular peduncle, acumen reaching midlength of ultimate podomere; margins not thickened and little elevated; upper surface subplane and studded with small, shallow, setiferous punctations. Subrostral ridge very weak and evident in dorsal aspect only in caudalmost orbital region. Postorbital ridge moderately well developed, grooved dorsolateraly and terminating cephalically in small spine. Suborbital angle very small but subacute. Branchiostegal spine small and acute. Cervical spine acute but comparatively small.

Abdomen and carapace subequal in length. Pleura of third through fifth abdominal segments slightly convex ventrally and each with caudoventral angle. Cephalic section of telson with 2 spines in each caudolateral corner. Cephalic lobe of epistome (Figure 1h) subcircular, heavily fringed, and with tiny subangular prominences cephalolaterally; fovea distinct and comparatively deep. Ventral surface of proximal podomere of antennular peduncle with strong mesial spine approximately at midlength. Antenna with small spines on basis and ischium; flagellum extending caudally beyond telson by about one-half length of abdomen. Antennal scale (Figure 1l) approximately 2.6 times longer than broad, widest proximal to midlength; greatest width of lamellar portion about twice width of thickened lateral part.

Third maxilliped extending cephalically to level of distal end of proximal podomere of antennular peduncle; ischium with distolateral extremity angular but not produced, its lateral half bearing conspicuous tufts of plumose setae.

Right chela (Figure 1m) subovate in cross section, not strongly depressed. Mesial surface of palm with row of 8 tubercles flanked by additional tubercular rows above and below, those on mesial third distinctly elevated above surface of palm, those occurring more laterally becoming progressively more squamous. Both fingers with low but distinct longitudinal ridges flanked by setiferous punctations and few tubercles basally; ridges on ventral surface of fixed finger more prominent. Opposable margin of fixed finger with row of 11 tubercles (third from base largest) along proximal three-fifths, and large acute tubercle on lower level slightly distal to midlength; band of minute denticles present along almost entire length of finger, very broad on distal three-fifths. Opposable margin of dactyl with 2 rows of tubercles: dorsal row of 11 (proximal 3 subequal in size and larger than others) along basal half, and ventral row of 9 (proximalmost largest) extending along second one-fifth of finger from base; band of minute denticles very broad, except along proximal fifth, extending along almost entire length of finger; few small tubercles among denticles between dorsal and ventral rows.

Carpus of cheliped longer than broad with very shallow oblique furrow dorsally, tuberculate mesially and dorsomesially; mesial surface with only 1 tubercle conspicuously larger than others and spiniform tubercle present on dorsomesial distalangle; ventrodistal surface with usual 2 tubercles, more mesial one reduced in size; remainder of podomere with setiferous punctations.

Merus tuberculate dorsally, distomesially, and ventrally; 2 dorsal preapical tubercles larger than others on dorsal surface; ventral surface with irregular mesial row of 16 (15 on left cheliped) tubercles and lateral one of 15, also additional tubercles flanking rows. Ischium with row of 5 (4 on left cheliped) tubercles ventromesially.

Hooks on ischia of third and fourth pereiopods (Figure 1k) simple, that on third overreaching basioischial articulation, neither opposed by tubercle on corresponding basis. Coxa of fourth pereiopod with strong, inflated, vertically disposed caudomesial boss. Coxa of fifth with flattened (in longitudinal axis of body) narrow boss caudomesially.

Sternum between second, third, and fourth pereiopods rather deep with prominent mat of plumose setae extending mesially from ventrolateral margins.

First pleopods (Figure 1c,e,g,j) as described in “Diagnosis.” In addition, proximomesial lobe of both members of pair conspicuously large and inflated. Uropod with both lobes of basal podomere bearing comparatively short, acute spines; distomedian spine on mesial ramus lying distinctly proximal to distal margin of ramus.

ALLOTYPIC FEMALE.—Disregarding secondary sexual characters, differing from holotype in following respects: suborbital angle virtually obsolete, broadly rounded; cephalodextral margin of cephalic lobe of epistome without prominence; antenna reaching slightly beyond midlength of telson; mesial margin of palm of chela with row of 7 tubercles; opposable margin of fixed finger of chela with row of 6 and 7 tubercles (second from base largest) on right and left members, respectively, and minute denticles largely limited to single row; opposable margin of dactyl distinctly excavate basally, bearing single row of 8 (right chela) or 9 (left) tubercles (second from base largest), and minute denticles almost restricted to single row; only 1 subdistal tubercle on dorsal surface of merus. ventrolateral margin with row of 8, and ventromesial margin with row of 16 and 14 on right and left chelipeds, respectively, and corresponding ischia with 4 and 3; sternum between second, third, and fourth pereiopods somewhat shallower than in male and, as usual, lacking mat of plumose setae; caudal portion of plate tuberculate and with paired tuberculate prominences slightly overhanging annulus. (See “Measurements.”)

Annulus ventralis (Figure 1b) as described in “Diagnosis.” First pleopod reaching cephalic margin of annulus.

MORPHOTYPIC MALE, FORM II.—Differing from holotype in following respects: suborbital angle reduced as in allotype; cephalolateral margins of cephalic lobe of epistome without prominences; antenna reaching caudal margin of telson; third through fifth pleura more nearly truncate ventrally; fixed finger of chela with row of 12 and 13 tubercles on right and left members, respectively; corresponding margins of dactyl with dorsal rows of 21 and 19, and ventral rows of 5 and 8, respectively; only 1 spiniform subdistal tubercle on dorsal surface of merus of cheliped, ventral surface with mesial row of 15 (right) and 13 (left) and lateral row of 8 tubercles; hooks on ischia of third and fourth pereiopods much reduced, neither overreaching basioischial articulation; bosses on coxae of fourth and fifth pereiopods only slightly less conspicuous. (See “Measurements.”)

First pleopod (Figure 1d,f) with all terminal elements described for holotype present but all except mesial process much reduced in size and none corneous; all disposed as in holotype.

COLOR