Orconectes (Hespericambarus) cyanodigitus
Creators: name: Johnson, Daniel P.
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Cambaridae
Orconectes
Orconectes cyanodigitus

description: Orconectes (Hespericambarus) cyanodigitus
Red River Painted Crayfish new species
Figs 2–6, 8, Table 1
Diagnosis. Body pigmented, eyes well developed. Rostrum with marginal spine and lacking median carina. Carapace with strong cervical spine. Areola obliterated along much of its length. Suborbital angle obtuse, branchiostegal spine strong. Antennal scale about 3.0 times as long as broad and widest near midlength. Ischium of third pereiopod with simple strong hook not overreaching basioischial articulation. Gonopod (first pleopod) of form I male reaching cephalic margin of coxa of third pereiopod when abdomen flexed, symmetrical; terminal elements two (mesial process and central projection); central projection corneous, blunt-tipped, recurved with apex directed at about 45 degrees to main shaft, caudal extent less than half caudal extent of mesial process; mesial process noncorneous, distinctly longer than central projection and recurved with tip directed about 120 degrees from axis of shaft. Female with annulus ventralis subrhomboid, wider than long, fused to sternum, cephalic fourth poorly calcified, sinus extending from near caudal margin to near cephalic margin and sinuous with no distinct fossa.
Holotypic male, form I. Cephalothorax (Fig. 2, 3 a, b)3 subcylindrical, slightly depressed. Second abdominal segment narrower than cephalothorax (12.0 and 14.3 mm, respectively). Areola obliterated over much of its length. Cephalic portion of carapace 1.9 times as long as areola, latter 34.1% of total carapace length and 46.0% of postorbital carapace length. Carapace laterally granulate and dorsally punctate with the
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mediodorsal cephalic region weakly so. Rostrum bearing well developed lateral spine; tapering from base; concave and lacking median carina; median area unadorned, lateral area with punctations; margin slightly thickened; corneous tip of acumen upturned and reaching distal end of ultimate podomere of antennular peduncle. Postorbital ridge well developed and bearing anterior spine. Suborbital angle obtuse. Branchiostegal and cervical spines well developed.
Abdomen slightly longer than carapace (32.1 and 30.2 mm, respectively); terga sparsely punctate; pleura moderately punctate. Cephalic section of telson (Fig. 3 i) with two spines in each caudolateral corner. Ventral surface of proximal podomere of antennular peduncle with spines at 75% distance from base. Antennal peduncle with well developed spines on basis and ischium. Antennal scale (Fig 3 j) 3.1 times as long as broad, widest near midlength; greatest width of lamellar area 1.4 times width of lateral thickened area.
Third maxilliped extending to position of spine on basal podomere of antennular peduncle; ventral surface of all podomeres bearing plumose setae, but not so much as to completely obscure surface.
Right chela (Figs. 3 c–f) subovate, depressed and somewhat gaping; palm 1.4 times as broad as mesial margin length, latter 25% of chela length. Dorsum of palm moderately punctate laterally and punctate with a few tubercles mesially; venter of palm weakly punctate except near lateral margin where more densely punctate. Mesial margin of palm bearing row of 9 tubercles bordered dorsolaterally by a second row of 10 tubercles. Fixed finger costate and densely covered with punctations dorsally, ventrally densely punctate; opposable margin with row of 11 tubercles (left chela with 13), 6th from the base largest, basal third bearing plumose setae (matted in photo); lateral margin with well defined row of punctations. Dactyl densely punctate dorsally and ventrally; low groove on dorsal surface bordering opposable margin; opposable margin with 11 tubercles (left chela with 13), proximal 5 similar in size (3rd and 4th slightly smaller) and distinctly larger than others, remainder decreasing in size distally; on left chela 1st, 2nd and 6th tubercles similar is size and larger than others; mesial margin with central row of well defined tubercles bordered dorsally by another row of smaller tubercles and ventrally by poorly defined row of tubercles. Both dactyl and fixed finger bearing row of minute denticles (broken by tubercles) on distal half.
Carpus of cheliped slightly longer than broad with longitudinal furrow flanked laterally by punctations and mesially by tubercles; mesial margin with 3 spiniform tubercles, one at midlength pronounced; ventral surface with two prominent spiniform tubercles on distal margin, otherwise relatively unadorned
Merus dorsally with two spiniform tubercles on distal fourth, otherwise very weakly punctate except for distal fourth where moderately punctate; mesial and lateral surfaces weakly punctate, with lateral spiniform tubercle on distal margin; ventral surface (Fig. 3 g) with two marginal rows of spiniform tubercles, lateral row with 6 and mesial row with 12, tubercles decreasing in size proximally in both rows; between rows surface is punctate. Ischium bearing sufflamen and with single small spiniform tubercle on ventral surface at 60% of length.
Hook on ischium of 3rd pereiopod (Fig. 3 h) simple, not overreaching basioischial articulation and opposed by very weak prominence.
Gonopod (Figs. 4 a–c) as described in "Diagnosis".
Uropod (Fig. 3 i) with both lobes of basal podomere bearing single acute spines; mesial ramus with well developed median carina terminating in distinctly premarginal spine and strong distolateral spine.
Allotypic female. Differing from holotype, other than in secondary sexual characteristics, in following respects: width of abdomen only slightly less than cephalothorax (15.0 and 15.8 mm, respectively); ventral surface of proximal podomere of antennular peduncle bears two spines, one similar to that of male, the other smaller and at midlength; palm 1.3 times as broad as mesial margin length, latter 29% of chela length; mesial margin of palm bearing row of 10 tubercles; fixed finger's opposable margin with row of 12 tubercles (left chela with 11), 5th from the base largest, plumose setae on basal third more pronounced; dactyl's opposable margin with 12 tubercles (left chela with 14); merus dorsally with three spiniform tubercles on distal fourth. Annulus ventralis (Fig. 5 a) as in diagnosis. First pleopod present.
Morphotypic male, form II.—Differing from holotype, other than in secondary sexual characteristics, in following respects: areola length 34.1% of total carapace length; tip of rostrum reaching midlength of ultimate podomere of antennular peduncle; antennal scale 2.8 times as long as broad; mesial margin of palm of right chela with row of 11 tubercles bordered dorsolaterally by a second row of 7 tubercles; opposable margin of fixed finger with row of 14 tubercles (left chela with 11), 7th from the base largest; opposable margin of dactyl with 14 tubercles (left chela with 13), proximal 6 similar in size and distinctly larger than others; ventral surface of merus with lateral row of 5 tubercles and mesial row of 13; hook on ischium of 3rd pereiopod present but slightly less pronounced. Gonopod (Figs. 4 d, e) with both processes noncorneous and much shorter and thicker than holotype; central projection directed about 45 degrees to axis of shaft; mesial process directed about 60 degrees.
Color notes. Holotype (Fig 2): Predominant coloration olive. Cephalic part of carapace slightly more bluish and obscurely mottled with dark and light patches; caudal fourth darker than remainder; sides with diffuse broad light longitudinal stripe. Rostral margin caudal to marginal spine pale yellow. Margin of acumen white. Postorbital ridge with narrow pale yellow line. Orbit rimmed with reddish orange. Thoracic part of carapace obscurely freckled with dark spots dorsally. Side with dark kidney-shaped blotch caudal to and parallel to cervical groove (ventral half darker); and dark diffuse longitudinal lateral stripe, bordered below by diffuse light stripe, which in turn bordered by diffuse dark stripe on ventral margin. Caudal margins of terga tinged with red then bordered cephalically by blue-black, then diffuse dull light blue. Pleura bluish with dorso-ventrally oriented pale yellow stripe on ventral half. Red spots located at cephalic edge of junction of terga and pleura. Terga and uropod progressively more bluish distally with red-orange margins. Flagella of antenna and antennule tan. Palm, carpus and distal half of merus of cheliped dorsally olive with black spots of two sizes, and ventrally cream with few spots. Fingers basally greenish blue on dorsum (bluish cream ventrally) becoming intense blue distally and with distal 10% red-orange. Prominent tubercles on merus, carpus, palm and margins of fingers mostly cream. Distinctive spots of red occur at all pereiopod articulations. Venter of cephalothorax and abdomen mostly cream.
Type locality. Pat Mayse Lake, Lamar County, Texas (33.84353° N, 95.54163° W). Water moderately clear; many rocks along shore, some natural, others artificially placed; sparse aquatic vegetation; water substrate sandy near shore, some clay on shore; water depth where crayfish found 5 to 15 cm.
Disposition of types. The holotype, allotype and morphotype (ɗI, Ψ, ɗII) are deposited in the National Museum of Natural History (Smithsonian Institution), nos. 1145301, 1145302 and 1145303, respectively. Paratypes are deposited in the Illinois Natural History Survey Crustacean Collection.
Size. The largest specimen examined is a form I male with a carapace length of 42.2 (postorbital carapace length 31.4) mm. The largest female has a carapace length of 40.0 (30.8) mm. The smallest first form male has a carapace length of 20.8 (15.5) mm. Ovigerous females or ones carrying young have not been collected.
Range and specimens examined. A total of 103 specimens (41 ɗI, 9 ɗII, 53 Ψ) of this crayfish has been collected by the author at seven localities in the Red River watershed along the border of Texas with Oklahoma and Arkansas (Fig. 6). Lamar County, Texas: (1) Type locality, 21 ɗI, 7 ɗII, 27 Ψ, 28 Sep 2008, 5 ɗI, 3 Ψ, 27 Sep 2008; (2) Stream near Junction of Red River and Route 271 (33.87468° N 95.50218° W), 2 ɗI, 1 ɗII, 6 Ψ, 27 Sep 2008, 3 ɗI, 5 Ψ, 28 Sep 2008; 1 Ψ, 30 Sep 2007; (3) Pat Mayse Lake spillway (33.85548° N 95.55370° W), 5 ɗI, 1 ɗII, 9 Ψ 30 Sep 2007; (4) Pine Creek @ Route 906, (33.85581° N 95.34131° W), 3 ɗI, 1 Ψ, 30 Sep 2007. Red River County, Texas: (5) Red River @ Route 37 (33.86025° N 95.03128° W), 1 ɗI, 13 Oct 2007. Bowie County, Texas: (6) Red River @ Route 259, (33.68553° N 94.69420° W), 1 Ψ, 13 Oct 2007. Little River County, Arkansas: (7) Red River @ Hwy 59 (33.55113° N 94.04125° W), 1 ɗI, 13 Oct 2007.
Variations. The form I male gonopod shows remarkably little variation (Figs. 4 a–c, f–r). The ratio of length central projection to total appendage length varies from 19.5% to 24.2% (mean 21.9% ± 1.4). The same ratio for mesial process varies from 21.0% to 27.2% (mean 23.3% ± 1.6). The gonopods of smaller form I males are comparatively more robust. In one male from locality 5 (Fig. 4 r), the central projection extends caudally almost to the mid caudal extent of the mesial process; in all specimens from the type locality the caudal extent of central projection is very uniform. The annulus ventralis (Fig. 5) length/width ratio varies from 62.2% to 72.2% (mean 66.7%); dextral and sinistral sides are flipped about half the time. Color pattern varies significantly (Fig. 8), with some individuals distinctly and heavily freckled; ground color varies from light to dark with the hue varying from greenish to reddish to tan.
Relationships. This crayfish is apparently most closely related to O. deanae (Reimer and Jester, 1975) and O. difficilis (Faxon, 1898). The central projection of O. difficilis is similar to the new taxon, but slightly less recurved; the mesial process is however much shorter and is distinctly shorter than the central projection. In O. deanae, the mesial process is very similar to that of the new taxon, but the central projection is longer and nearly always more recurved with its tip directed about 90 degrees to the shaft axis, and extends caudally well beyond the mid caudal extent of its mesial process, and the tip is more acute. The annulus ventralis of the new taxon, O. difficilis and O. deanae are similar. The color pattern of O. deanae is on average less freckled and lighter, based on a large series of specimens from the Brazos River system. I have been unable to find photographs of O. difficilis from the Canadian River for comparison. Apparently more distantly related is O. maletae (Walls, 1972); its central projection is relatively longer and more acute; its mesial process is less separated from the central projection and is recurved only to about 90 degrees from the axis of the main shaft; the annulus ventralis has a crosswise crease; the areola is obliterated only for a small length; and the color pattern is very different.
Etymology. Cyano (Gr.) = blue + digitus (L.) = finger; alluding to the blue on the chela's fingers. Associates. This crayfish has been found nearly without associates. At all locations only two Procambarus acutus acutus have been collected with this crayfish.
description: Published as part of Johnson, Daniel P., 2010, Four new crayfishes (Decapoda: Cambaridae) of the genus Orconectes from Texas, pp. 1-45 in Zootaxa 2626 on pages 3-11, DOI: 10.5281/zenodo.276049