Faxonius wagneri, Fetzner Jr & Taylor, 2018

Fetzner Jr, James W. & Taylor, Christopher A., 2018, Two new species of freshwater crayfish of the genus Faxonius (Decapoda: Cambaridae) from the Ozark Highlands of Arkansas and Missouri, Zootaxa 4399 (4), pp. 491-520 : 507-515

Faxonius wagneri , new species

Figures 6–7 , Table 4

Orconectes eupunctus .— Williams, 1952 [in part].

Orconectes (Crockerinus) eupunctus .— Fitzpatrick, 1987 [in part], Hobbs, 1989 [in part]. Faxonius eupunctus .—Crandall and De Grave, 2017:629 [in part].

Diagnosis. Body and eyes pigmented ( Fig. 6 ). Rostrum deeply excavated, terminating in long acumen; no median carina. Rostral margins thickened; margins straight, subparallel and slightly converging; terminating in spines ( Fig. 7H ). Areola 32.3–38.7% ( = 34.0%, n = 32, SD = 0.01) of total length of carapace, narrowest part at midpoint, 3.8–10.9 ( = 6.6, n = 32, SD = 1.6) times as long as wide, with two to three (mode = 2, n = 32, SD = 0.5) punctations across narrowest part ( Fig. 7H ). One (rarely two (6.3%)) corneous cervical spines on each side of carapace ( Fig. 7A ). Postorbital ridges well developed, terminating in corneous spines ( Fig. 7H ). Suborbital angle obsolete ( Fig. 7A ). Antennal scale broadest distal to midlength, thickened lateral margin terminating in large corneous spine ( Fig. 7G ). Ischia of third pereiopods of males with hooks; hooks overreaching basioischial articulation in Form- I males only. Chela with two or three rows of tubercles (see Variation) along mesial margin of palm, usually six to ten tubercles in mesialmost row and four to ten in dorsomesial row, third row, if present, with few scattered tubercles; dorsal surfaces of fingers lacking well defined longitudinal ridges ( Fig. 7K ). Mandible with serrate-edged incisor region. Cephalomedian lobe of epistome subpentagonal to subtriangular without cephalomedian projection; epistomal zygoma forming weak arch. First pleopods of Form-I male symmetrical, extending to posterior edge of base of first pereiopods when abdomen flexed forward. First pleopod of Form-I male with shoulder on cephalic surface at base of central projection ( Fig. 7B, C, F ); central projection corneous, constituting 37.4–45.5% ( = 41.3%, n = 16, SD = 0.02) of total length of first pleopod, continuous with main shaft of pleopod, tapering to a pointed tip, slightly arched and twisted caudolaterally; mesial process equal to or slightly subequal in length to central projection, non-corneous, tapering to an acute tip, tip arched cephalomesially ( Figs. 7B, C, F ). Central projection of Form-II male non-corneous, constituting 20.6–25.1% ( = 23.3%, n = 6, SD = 0.02) of total length of first pleopod, extending to posterior edge of bases of first pereiopods when abdomen flexed forward; central projection straight, mesial process arched slightly cephalolaterally and subequal in length; both elements tapering to rounded tips ( Figs. 7D, E ). Annulus ventralis immovable, subrhomboidal; cephalic half with deep and wide median trough and two caudally directed protuberances overhanging centrally located cavernous fossa; sinuate sinus running from near center of fossa to caudal edge on a raised centrally located rounded hump ( Fig. 7I ).

Description of holotypic male, form I. Specimen slightly soft, a recently molted individual. Body slightly depressed dorsoventrally, carapace wider than abdomen (15.9 and 13.0 mm, respectively). Greatest width of carapace larger than height at caudodorsal margin of cervical groove (15.9 and 13.8 mm, respectively). Postorbital carapace length 82.4% of total length of carapace. Areola 7.4 times longer (11.2 mm) than wide (1.5 mm) with two punctations across narrowest part; length of areola 37.0% of total length of carapace. Rostrum deeply excavated dorsally, floor smooth, lacking carina; margins thickened, straight and slightly converging, terminating in corneous marginal spines. Acumen long and terminating in corneous spine, reaching posterior margin of third antennal peduncle. Postorbital ridges well developed, terminating in corneous spines. Suborbital angles obsolete. One corneous cervical spine on both sides. Antennal scale as in Diagnosis ( Fig. 7G ). Right antennal scale 5.9 mm long, 2.4 mm wide. Epistome as in Diagnosis.

Abdomen longer than carapace (31.6 and 30.3 mm, respectively). Cephalic section of telson bearing two spines in each caudolateral corner, more mesial pair movable. Proximal podomere of uropod with spine extending over mesial ramus and spine in caudolateral corner extending over lateral ramus. Caudal margin of cephalic section of lateral ramus with 20 (left) and 23 (right) fixed spines and one larger movable spine in caudolateral corner, lateral ramus with median ridge lacking terminal spine. Lateral margin of left mesial ramus terminating in spine, spine missing on right; mesial ramus with prominent median ridge terminating in premarginal spine. Dorsal surfaces of telson and uropods setiferous.

Mesial surface of palm of right chela with two rows of tubercles, those more distal less well defined, ten tubercles in mesialmost row, six tubercles in second dorsomesial row, with several additional tubercles interspersed in between these two rows. Mesial and lateral surfaces of chela, and opposable margins of fingers, covered with numerous punctations; dorsal surface with scattered punctations, ventral side with scattered puncations mostly on lateral half. Dorsal surface of finger of propodus with weak submedian longitudinal ridge, more pronounced near tip of finger; basal half of opposable margin with seven tubercles, first two roughly the same size, third tubercle from base of finger largest, remaining tubercles slightly smaller with sixth the smallest. One additional large tubercle offset mesially onto inner margin of finger half-way between seventh tubercle and tip. Dorsal surface of dactyl with weak submedian longitudinal ridge flanked by setiferous punctations; basal half of opposable margin with eight tubercles, first three of roughly the same size, fourth tubercle from base of finger largest, fifth through seventh roughly the same size, eighth smallest of all and slightly offset. Dactyl with subterminal corneous tip, corneous tip on propodus broken off.

Right carpus with moderately deep oblique furrow dorsally; dorsal surface with one spiniform tubercle at distomesial corner; mesial margin with one large corneous procurved spine at midlength, and small bump posteriorly; ventral surface with one large corneous spine just lateral to midlength of distal margin, one spiniform tubercle just mesial to midlength of distal margin ( Fig. 7K ). Dorsal surface of merus with two centrally located large corneous spines ( Fig. 7J ); ventral surface with one large corneous spine at distolateral corner and mesial row of five spines, row terminating in large corneous spine. Ischium lacking corneous spine just proximal to midlength of mesial margin, one large tubercle on distal end of mesial margin.

Hook on ischium of third pereiopod only; hook simple, overreaching basioischial articulation, opposed by low tubercle on basis. First pleopod of Form-I male with shoulder on cephalic surface at base of central projection; central projection corneous, constituting 42.9% of total length of first pleopod, parallel to main shaft of pleopod, tapering to pointed tip, tip directed caudolaterally; mesial process subequal in length to central projection, noncorneous, tapering to acute tip, tip arched cephalomesially ( Figs. 7B, C, F ).

Description of allotypic female. Except for secondary sexual characteristics, differing from holotypic male in the following respects. Areola constituting 32.6% of length of carapace and eight times longer than wide, with three punctations across narrowest part. Postorbital carapace length 77.0% of length of carapace. Abdomen wider than carapace (12.7 and 10.3 mm, respectively). Mesial surface of palm of right chela with two full rows of tubercles, nine tubercles in dorsomesial row. Two tubercles in third row adjacent to distal-most tubercles in second row. A few other scatterd tubercles, one between the two main rows and a few on inner surface of palm margin. Finger of propodus with basal half of opposable margin with ten tubercles, first three roughly the same size, fourth tubercle from base of finger largest, remaining tubercles decreasing in size toward tip of finger. Tenth tubercle larger and offset distally and mesially from others. Basal half of opposable margin of dactyl with ten tubercles, first four of roughly the same size, with fourth slightly larger, remaining six slightly decreasing in size toward tip of dactyl with last two small and hard to distinguish. Caudal margin of cephalic section of lateral ramus of uropod with 19 fixed spines.

Sternum between third and fourth pereiopods narrowly V-shaped. Postannular sclerite 78% as wide as annulus ventralis (described in Diagnosis)( Fig. 7I ). First pleopod uniramous, barely reaching caudal margin of annulus when abdomen flexed.

Description of morphotypic male, form II. Differing from holotype as follows. Areola constituting 33.8% of length of carapace, 6.8 times longer than wide, and with 3 punctations across its narrowest part. Postorbital carapace length 78.1% of length of carapace. Left chela regenerated. Mesial surface of palm of right chela with two irregular rows of tubercles, nine tubercles in dorsomesial row. Numerous interspersed scattered tubercles. Extra two tubercles in partial third row located near distal end. Ventral surface of right merus with two large corneous spines at distolateral corner, with mesial row of six spines. Hook on ischium of third pereiopod not overreaching basioischial articulation. First pleopod as described in Diagnosis.

Size. The largest specimen examined was a 33.1 mm CL Form-I male. Females (n = 10) ranged in size from 18.6 to 30.9 mm CL ( = 23.6 mm). Form-I males (n = 16) ranged from 19.2 to 33.1 mm CL ( = 28.1 mm). Form-II males (n = 6) ranged from 18.9 to 31.2 mm CL ( = 24.2 mm).

Color. Base color of dorsal and lateral surfaces of cephalothorax brown to dark brown ( Fig. 6 ), rarely appearing more reddish to purplish. Black saddle crossing the juncture of posterior edge of carapace and anterior edge of abdomen, roughly equally divided onto both surfaces. Lateral sides of first abdominal pleuron with orangish, cream or yellowish patch that interupts saddle, making patches stand out. Dorsal surface of abdomen with broken or irregular triangular-shaped posteriorly tapering blackish stripe, fading out just before reaching tail fan. Posterior margin of each abdominal segment sometimes highlighted in red, especially in recently molted individuals. Lateral surfaces of abdomen and tailfan olivaceous green, with distal margins of latter sometimes appearing light yellow to cream. Walking legs olivaceous green, fading to cream near junction with body, with hints of light yellow or light red at articulation joints. Chelae and carpus overall olivaceous green, with dactyl and propodus appearing a darker green than palm region. Tips of both fingers light orange to light red, then quickly transitioning to olivaceous green. Spines and tubercles on chela carpus same color as base color. Distal half of merus olivaceous green, the remainder cream colored. Ventral surfaces of cephalothorax and abdomen cream to white with hints of light yellow on basal segement of walking legs. Ventral surface of chelae are mostly cream colored, especially on lateral half, but mesial one third can be light olivaceous green. Fingers olivaceous green or combination of cream and olivaceous green. In Form-II males, the first and second pleopods have hints of light pink or light red, with the tips of the first pleopod typically having a much darker shade than rest of the appendage.

Type locality. Eleven Point River at confluence with Diles Creek , 5.1 km NW Dalton, Randolph County, Arkansas (36.453906, -91.180904, WGS 84, 104 m).

Disposition of types. The holotypic male (Form-I), allotypic female, and morphotypic male (Form-II), are housed in the crustacean collection of the Carnegie Museum of Natural History (accession numbers 38752, 38753, 38754, respectively). Paratypes consisting of seven lots are housed at CMNH (38760, 38761, 38762, 38763, 38764 and 38775) and INHS (10504).

Range and specimens examined. Currently known to be endemic to the mainstem of the Eleven Point River from Oregon County, Missouri to Randolph County, Arkansas. The collection lots from CMNH and INHS below are referenced using their museum accession numbers.

ARKANSAS: Randolph County: (1). Eleven Point River downstream of Dalton boat ramp, 0.2 km E Dalton, 36.421044, -91.139249 (WGS84), 15-Apr-2017, coll: JW Fetzner Jr., BK Wagner and D Filipek , CMNH-38754 , 1 MII (Morphotype). (2). Eleven Point River above Dalton , 2.1 km N Dalton , 36.43988, -91.14478 (WGS84), 04- Aug-2011, coll: BK Wagner , CMNH-38761 , 1 MI, 1 F. (3). Eleven Point River at Vern's Hole ( Jones Creek confluence), 3.9 km SE Dalton, 36.3935, -91.1147 (WGS84), 30-Aug-2005, coll: BK Wagner, K Irwin and B Posey, INHS-10540, 3 MI. (4). Eleven Point River downstream of Diles Creek confluence, 4.4 km NW Dalton, 36.45033, -91.17533 (WGS84), 01-Aug-2005, coll: BK Wagner and K Irwin, INHS-10591 , 2 F. (5). Eleven Point River upstream of Diles Creek confluence, 4.7 km NNW Dalton, 36.4599, -91.1629 (WGS84), 16-Aug-2005, coll: BK Wagner and K Irwin, INHS-10509, 5 MI. (6). Eleven Point River at Woody's Run , 5.1 km NW Dalton, 36.45509, -91.18096 (WGS84), 03-Aug-2011, coll: BK Wagner, CMNH-38760 , 2 MI, 2 MII, 3 F ; CMNH-3 8752, 1 MI (Holotype); CMNH-38753 , 1 F (Allotype). (7). Eleven Point River just above confluence with Diles Creek, 5.1 km NW Dalton , 36.453906, -91.180904 (WGS84), 24-Jul-2012, coll: M Nolen , CMNH-38762 , 2 MI, 1 MII, 2 F. (8). Eleven Point River at Woody's Run, 5.2 km NW Dalton , 36.456, -91.1802 (WGS84), 17-Aug-2005, coll: BK Wagner and K Irwin, INHS-10504, 3 MI , 1 F. (9). Eleven Point River below Dalton, 2.3 km SSE Dalton , 36.40308, -91.12985 (WGS84), 04-Aug-2011, coll: BK Wagner, CMNH-38775 , 4 MI, 2 MII , 3 F. MISSOURI : Oregon County: (10). Eleven Point River at the U.S. Forest Service Riverton East River Access, 0.2 km NE Riverton, 36.649041, -91.2000 (WGS84), 16-Apr-2017, coll: JW Fetzner Jr. , CMNH-38764 , 1 MII. Additional Collections (examined but not measured): ARKANSAS: Randolph County: (11). Eleven Point River downstream of Dalton boat ramp, 0.2 km E Dalton, 36.421044, -91.139249 (WGS84), 15-Apr-2017, coll: JW Fetzner Jr., BK Wagner and D Filipek , CMNH-38763 , 2 MI. MISSOURI : Oregon County: (12). Eleven Point River at the U.S. Forest Service Riverton East River Access, 0.2 km NW Riverton, 36.64937, -91.20001 (WGS84), 17-Sep-1984, coll: WL Pfleiger, INHS-13206, 1 F, 1 F juv. (13). Eleven Point River , 9.8 km NE Myrtle, 36.56004, -91.179781 (WGS84), 02-Aug-2017, coll: CJ Rice, INHS-15712, 1 MII , 3F. (14). Eleven Point River, 18.3 km NNE Myrtle, 36.6620, -91.1936 (WGS84), 25-Jul-2017, coll: CJ Rice, INHS-15714, 1 MI. (15). Eleven Point River , 14.2 km ENE Alton, 36.7536, -91.2595 (WGS84), 17-Jul-2017, coll: CJ Rice, INHS-15716 , 2F. Additional historical records depicted on the map ( Fig. 10 ) are from the AGFC crayfish distribution database (B.K. Wagner, personal communication).

Habitat and life history notes. Faxonius wagneri has only been found in the mainstem of the Eleven Point River, typically associated with gravel or coble substrates. The species was most commonly encountered in areas of the river with lower water flow (side channels, along banks, etc.). The species seems to be more common in the Arkansas portion of its range, being known from only ten specimens from four sites in Missouri.

Occurrence data are currently limited to the available museum collections. These collections were only made during three months out of the year, April, July and August, so the presence of various forms for other months is unknown. These data indicate that Form-I and Form-II males are both present in the population during all three months. No ovigerous females or females carying young were available in the collections. No other life history data are available for this species.

Etymology. This species is named in honor of Brian K. Wagner of the Arkansas Game and Fish Commission. Brian initially collected specimens of this species and noted that they looked different from the typical F. eupunctus , which are found in the same streatch of the Eleven Point River. Brian has worked extensively with the crayfish fauna of Arkansas, and it is our pleasure to name this species after him.

Crayfish associates. Other crayfish found in association with Faxonius wagneri include F. eupunctus ( Williams, 1952) , F. ozarkae ( Williams, 1952) , F. punctimanus Creaser, 1933 and Cambarus hubbsi Creaser, 1931 .

Variation. In addition to the range of ratios and counts given in the Diagnosis section, other morphological variations seen in F. wagneri include the following. On the chela palm margin, there were either two or three rows of tuberlces (third only a partial row), and occasional scatered tubercles that may be interspersed between the rows or as a small cluster of tubercles distolateral to the lateral-most tubercle row. The number of spines on the ventral side of the carpus was variable, ranging from one to five (mode = 4). Some aspects of the dorsal color pattern of the carapace in this species can be variable, as described in the Color section.

Comparisons. Faxonius wagneri new species, differs from all other members of the genus by possessing a unique combination of male Form-I first pleopod, carapace, and rostrum characters. The Form-I male pleopod of F. wagneri , new species, is most similar in length and general shape to other members of the former subgenus Procericambarus ( Fitzpatrick 1987), which occur across the central and eastern United States. This subgenus, and all others in the former genus Orconectes , were not recognized in the latest world classification of freshwater crayfish (Crandall & De Grave, 2017). All members of the former Procericambarus subgenus generally possess long, straight first pleopod elements which may or may not curve at their distal tips and a central projection accounting for at least 33% of the total first pleopod length. Faxonius wagneri differs from all sixteen of the former Procericambarus members that occur west of the Mississippi River in possessing a Form-I first pleopod mesial process that is equal in width at its base to the central projection, a central projection which is 37–45% of total pleopod length, cervical spines, and relatively wide rostrum which lacks a median carina.

Relationships. See the Phylogenetics text in the Results section for a discussion of the relationships of this species to other taxa. See also Fig. 2 .

Common name. The suggested common or vernacular name for this species is the Eleven Point River Crayfish, in reference to the river where the species is found.

Conservation status. Given F. wagneri’ s currently known limited distribution in an approximate 85 km stretch of a single river (Eleven Point R.) and the known introduction of the non-native Ringed Crayfish ( F. neglectus ) in one tributary of the Eleven Point River upstream of F. wagneri’s range ( Imhoff et al. 2012), we recommend a status of Endangered following the criteria of the American Fisheries Society ( Taylor et al. 2007). These same factors warrant a classification of Endangered following the criteria of the International Union for the Conservation of Nature (IUCN).

Figures

FIGURE 2. Bayesian phylogeny depicting relationships among the new species and several other members of the genus from the Ozark Highlands.Numbers at the nodes indicate bayesianposterior probabilities.Clades A and B as discussed in text.

FIGURE 6. Dorsal view of Faxonius wagneri, new species, morphotype, male form-II (CMNH 38752) from near Dalton, Arkansas.

FIGURE7. Faxonius wagneri, new species; all from holotype male Form-I (CMNH 38752), except D and Efrom morphotype male Form-II (CMNH 38754), and I from allotype female (CMNH 38753). A) lateral aspect of carapace; B–C) mesial and lateral aspect of Form-I male first pleopod, respectively; D–E) mesial and lateral views of Form-II male first pleopod, respectively; F) mesial view of entire first pleopod of male Form-I gonopod; G) dorsal aspect of antennal scale; H) dorsal veiw of carapace; I) ventral aspect of the female annulus ventralis; J) dorsal aspect of merus of first pereiopod (=cheliped) showing location of spines; K) dorsal aspect of distal podomeres of the right cheliped. Plate by Guenter A. Schuster.

FIGURE 10. Map showing the location of museum specimens lots that were examined and measured morphologically as part of thisstudy.Faxonius roberti lotsexamined are shown as red opencircles and thetypelocality is depictedas an open redcircle with a cross. Recent historical locality records (specimens not measured) for F. roberti are indicated with black circles with squares. Faxonius wagneri lots are shown as purple closed circles and the type locality is indicated with a purple closed circle with a cross.Black circles with diamondsindicate other known localities for F.wagneri that were not measured as a part of this study. Black arrows indicate the location of the type localities for both species. Orange lines indicate county boundaries. Black lines indicated HUC8watershed boundaries.Blue lines indicate major rivers.Map was generated using GoogleMyMaps.