Orconectes incomptus Hobbs & Barr 1972

Orconectes incomptus

Orconectes pellucidus australis.—Hart and Hobbs, 1961:176 [not Rhoades 1941].

Orconectes pellucidus pellucidus.—Hart and Hart, 1966:9 [not Tellkampf 1844a].

DIAGNOSIS.—Albinistic; eyes reduced and without pigment; rostrum devoid of marginal spines or tubercles delimiting base of acumen, margins converging, its upper surface weakly concave and lacking median carina; postorbital ridges terminating cephalically, with or without small tubercles; hepatic area without spiniform tubercles; three or four small cervical tubercles present; areola 4.1 to 5.2 times longer than broad and constituting 39.6 to 43.0 percent of total length of carapace; chelae conspicuously inflated and setose; mesial surface of palm of chela with several irregular rows of tubercles; well-developed hooks on ischiopodites of third pereiopods only. First pleopod of first-form male with length of greatest cephalocaudal diameter of pleopod less than twice that immediately proximal to base of central projection, and terminating in three elements; short, broad, somewhat flattened mesial process directed caudodistad and partially obscuring central projection in caudal aspect; corneous central projection directed laterad; minute caudal process situated between mesial process and central projection; cephalodistal margin with rounded prominence at base of central projection. Annulus ventralis approximately 1.4 times broader than long and as illustrated in Figure 9k.

Holotypic Male, Form I: Body (Figures 9c, l) subovate, depressed. Abdomen narrower than thorax (8.9 and 9.9 mm in widest parts, respectively). Width of carapace greater than depth in region of caudodorsal margin of cervical groove (9.9 and 7.5 mm). Areola broad (4.6 times longer than wide) with scattered punctations, 4 or 5 across narrowest part. Cephalic section of carapace 1.5 times as long as areola. Length of areola 39.6 percent of length of carapace. Rostrum approximately 1.5 times as long as broad, shallowly excavate, and with acumen, although indistinctly set off at base, 1.5 times longer than width of rostrum at base; cephalic extremity reaching almost to distal end of peduncle of antennule; margins converging, not swollen, only slightly elevated, and devoid of spines or tubercles; upper surface with setiferous punctations; subrostral ridges moderately well defined and evident, in dorsal aspect, from caudal margin of orbit to almost half distance to base of acumen.

Postorbital ridges moderately well developed, grooved dorsolaterally, and terminating cephalically, one bluntly and other in minute corneous tubercle. Suborbital angle lacking. Branchiostegal spine small and acute. Four small cervical tubercles present on each side of carapace immediately caudal to cervical groove. Carapace punctate dorsally and granulate laterally; hepatic area with number of small tubercles but lacking spines. Abdomen shorter than carapace (21.7 and 22.2 mm). Cephalic section of telson with 2 strong spines in each caudolateral corner, mesial ones movable.

Epistome (Figure 9j) broadly rounded cephalically, with prominent cephalomedian extension and with cephalosinistral margin slightly undulate. Surface subplane and without setae. Eyes much reduced, not completely hidden beneath rostrum in dorsal aspect and extending cephalically about halfway between caudodorsal margin of orbit and base of acumen. Antennules of the usual form, with prominent spine on ventral surface distal to midlength of basal segment. Antennae extending caudally beyond telson. Antennal scale (Figure 9i) broadest distal to midlength and almost half as broad as long; outer thickened portion much narrower than lamellar area and terminating distally in prominent spine. Third maxillipeds extending almost to midlength of distal segment of peduncle of antenna. Chela (only left one present, and it regenerated) with palm inflated and finger long and comparatively heavy; mesial margin of palm approximately 1.2 times longer than width of palm; dorsal surface of palm tuberculate mesially, otherwise punctate; both tubercles and punctations with fine setae; ventral surface with tubercles proximomesially, otherwise punctate; most punctations and tubercles bearing conspicuously long setae; spine lacking from surface opposite base of dactyl; tubercles along mesial portion of palm sublinearly arranged, innermost row consisting of about 8 tubercles; lateral margin of palm subserrate, with 8 emarginations. Fingers not gaping; dorsal and ventral surfaces with poorly defined longitudinal ridges flanked by punctations bearing long setae: opposable margin of immovable finger with row of 9 small tubercles along proximal third and with 2 somewhat larger ones distal to and below row; crowded minute denticles present between tubercles and extending distally to base of corneous tip of finger; lateral margin of finger costate, grooved, and bearing setiferous punctations; opposable margin of dactyl with row of approximately 13 small tubercles along proximal half, with crowded minute denticles between tubercles and extending to corneous extremity of finger; setal tufts on both fingers conspicuously long. Carpus longer than broad, with mesial surface bearing one prominent spine and several tubercles, one of which spiniform; tubercles extending onto dorsomesial and ventromesial surfaces, otherwise punctate; ventrodistal margin with prominent spine mesially and another on boss articulating with ventral socket of propodus. Merus tuberculate dorsally and bearing two rows of spiniform tubercles ventrally, outer row consisting of 9 and inner of 15; additional small tubercles flanking both rows. Ischium with several tubercles along opposable margin but not arranged in discreet row.

Ischia of third pereiopods (Figure 9h) with strong, simple hooks; hooks not extending proximal to distal margin of basis. Ischia of fourth pereiopods without hooks. Coxae of fourth pereiopods swollen caudomesially but lacking prominent caudomesially projecting prominences. Coxae of fifth pereiopods with small mesially projecting prominences along cephaloventral base of phallic papilla.

First pleopods (Figures 9a, e, g) symmetrical, reaching coxae of third pereiopods when abdomen is flexed, and shallowly situated in sternal groove. Tip ending in three parts as described in diagnosis.

Allotypic Female: Differs from holotype in following respects: margins of rostrum with distinct interruptions at base of acumen; subrostral ridges visible in dorsal aspect for only a short distance cephalic to caudal margin of orbit; postorbital ridges ending cephalically without spines or tubercles; cervical tubercles extremely small and hepatic tubercles almost obsolete; abdomen distinctly longer than carapace (23.4 and 22.2 mm); epistome with cephalolateral angles and ventral surface bearing setae; antennae extending caudad almost to end of telson; chela with mesial row of 10 tubercles along margin of palm; ventral surface of palm with small tubercle at base of articulation with dactyl; opposable margin of immovable finger with row of 7 tubercles (fourth from base largest) along proximal two-thirds and large one below row at base of distal two-fifths, between sixth and seventh tubercles; opposable margin of dactyl with row of 4 tubercles along proximal two-fifths; ventral surface of merus with two rows of 9 tubercles.

Annulus ventralis (Figure 9k) subovate, with median longitudinal elevation somewhat depressed and terrace-like caudal shelf, so obvious in O. australis australis, not delimited from general curvature; median longitudinal trough broad and shallow; cephalic end of sinus originating slightly dextral to median line, forming arc to median line and continuing caudally, ending on caudal margin of annulus.

Morphotypic Male, Form II: Differs from holotype in following respects: subrostral ridges scarcely visible in dorsal aspect; postorbital ridges very weak and terminating bluntly; cervical tubercles much reduced and hepatic tubercles almost obsolete; epistome more similar to that of allotype, with cephalolateral angle; antennae barely reaching cephalic margin of telson; right chela (Figure 9f) with mesial half of upper surface of palm tuberculate (11 in mesial row), otherwise punctate, lower surface of palm with tubercle at base of dactyl, outer margin of palm not serrate, opposable margin of fixed finger with row of 8 tubercles (fourth from base largest) along proximal two-thirds of finger and with single large tubercle below row near midlength of finger, opposable margin of dactyl with 9 tubercles (fourth from base largest) along proximal four-fifths of finger; ventral surface of merus of cheliped with mesial row of 8 tubercles and lateral one of 12; hooks on ischia of third pereiopods strong but not quite so well developed as in holotype, absent from fourth pereiopods; caudomesial prominences on coxae of fourth pereiopods and prominences on those of fifth obsolete.

First pleopod (Figure 9b, d) lacking trace of caudal process but with short tuberculiform mesial process and broad, prominent central projection; neither element corneous.

TYPE-LOCALITY.—Cherry Cave, lat. 36°28′09″N., long. 85°36′28″W, Jackson County, Tennessee. A description of the cave is presented in Barr, 1961:272–273.

MEASUREMENTS (in millimeters).—Orconectes incomptus:

DISPOSITION OF TYPES.—Holotype, allotype, and morphotype, USNM 130299, 130300, and 130301 (♂I, ♀, ♂II). Of the paratypes, 1 male, form II, and 1 ♂ are in the collection of H. H. Hobbs III; 6 males, form II, and 8 females are in the Smithsonian Institution.

SPECIMENS EXAMINED.—Specimens from Tennessee were examined as follows:

Jackson County: (1) type-locality, 1 ♀ I, T.C.B., VIII/8/59. (2) Carter Cave, lat. 36°16′53″N, long. 85°44′10″W, 1♂II, T.C.B., VI/9/55; 1♂, T.C.B., IX/1959; 5♀II, 6 ♀, J.E.C. and M.R.C., IX/21/68; 2♀II, 2 ♀, H.H.H. III, III/31/70. (3) Haile Cave, lat. 36°20′00″N, long. 85°43′08″W, 1 ♀, T.C.B., V/6/59.

See Barr, 1961, for detailed locations and descriptions of these caves.

VARIATIONS.—The range of variation among the available specimens is negligible, and the differences pointed out in the accounts of the primary types seem adequately to encompass those of any significance.

RELATIONSHIPS.—Although Orconectes incomptus has very close affinities with O. a. australis and O. a. packardi, we have no indication that intergrades exist between it and either of the subspecies of australis. Inasmuch as the differences between incomptus and australis are so similar to those that distinguish O. i. inermis from O. i. testii, we are tempted to treat incomptus as a subspecies of O. australis. Despite this similarity, there exists what we consider to be an important difference in that there is abundant evidence of intergradation between the southern inermis and the northern testii. In view of available data, it seems most improbable that the subterranean passages in Mississippian limestones on the eastern edge of the Cumberland Plateau (the range of australis) communicate with those of Ordovician limestones at the base of the Eastern Highland Rim (the range of incomptus), and if such connections do not exist, then it is highly unlikely that intergrades between the two might be found. The fact that the epizootic Dactylocythere ungulata Hart and Hobbs, the only entocytherid ostracod known to infest O. incomptus, occurs on both australis and incomptus does not necessitate the conclusion that such underground connections are present, for the same ostracod also occurs on Cambarus tenebrosus Hay which ranges from the Nashville Basin eastward to the Tennessee Valley, and it could have been responsible for transporting this ostracod via an epigean environment into the two subterranean systems.

SIZE.—The largest specimen available is a female having a carapace length of 24.5 mm. The only first-form male that we have seen is the holotype, in which the carapace length is 22.2 mm.

Orconectes incomptus is a species of crayfish in the family Cambaridae. It is endemic to Tennessee. It is also known as the Tennessee cave crayfish.

Orconectes incomptus eller «Tennessee cave 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 incomptus er en av de om lag 85 artene i slekten, og lever i elver og innsjøer nesten utelukkende i Tennessee.

Arten anses som sårbar (IUCN).

Orconectes incomptus é uma espécie de crustáceo da família Cambaridae.

É endémica dos Estados Unidos da América.