Creaserinus crenastylus, Johnson & Stern & Crandall, 2021

Johnson, Daniel P., Stern, David B. & Crandall, Keith A., 2021, The genus Creaserinus Hobbs, 1973 (Decapoda: Cambaridae) in Texas, Zootaxa 5017 (1), pp. 1-84 : 52-58

Creaserinus crenastylus n. sp.

Figs. 3, 5, 6a, g, 7b, f, j, 8a, b, 9–12, 25–29, Tables 1 , 3, 7, 11–13, 25, 26

Cambarus hedgpethi Hobbs, 1948:224–230 [in part; DeSoto Parish, LA record].

Fallicambarus hedgpethi .— Hobbs, 1969:111 [in part; by implication].

Fallicambarus (Creaserinus) fodiens .— Hobbs & Robison, 1989:672, Fig. 9q [in part].

Creaserinus fodiens .— Crandall & De Grave, 2017:627 [in part].

Diagnosis. Adults with rostrum devoid of marginal spines. Areola obliterated along part of its length. Antennal scale more than twice as long as broad. Cheliped with sufflamen. Lateral margin of chela costate, dorsal surface lacking tubercles on lateral half, ventrolateral surface lacking arched row of prominent setiferous punctations; opposable margin of dactyl with distinct excision in basal half; mesial margin bearing at least 2 rows of tubercles, those of main row extending from base at least two-thirds length of finger. Length of carpus distinctly less than width of palm of chela. Ventral surface of merus with mesial and lateral rows of tubercles. Mesial surface of chela of 2 nd pereiopod bearing prominent tufts of plumose setae. Hooks on ischia of 3 rd pereiopod only. Boss on coxa of 4 th pereiopod, rounded, slightly compressed and scarcely protruding ventrally. Gonopod of form I male lacking proximomesial spur and terminating in two distinct parts (mesial process and central projection). Central projection corneous, bladelike, bearing subapical notch, recurved approximately 135° to axis of shaft, with distal part directed caudoproximally with tip never crossing central projection of corresponding gonopod, and base not inclined laterally, length 31.5– 35.5% (x = 33.4, s = 1.2, n = 13) of total gonopod length. Mesial process noncorneous, recurved 110–135° to axis of shaft. Uropodal endopod with distolateral spine; distomedian spine premarginal. Telson divided with spine on anterolateral flank of suture. Function 6 positive when b refers to C. crenastylus n. sp. and a refers to any of other five Texas species (refer to Tables 3, 7, and 11–13). Distribution in Texas confined to Sabine River drainage in Sabine and San Augustine counties. Sex ratio of juvenile population (<16 mm CL) not strongly skewed female.

Holotypic male, form I. Eyes pigmented and with faceted cornea, but small. Body subcylindrical, very weakly depressed (Figs. 25a, b). Abdomen slightly narrower that cephalothorax (10.1 and 12.0 mm, respectively). Greatest width of carapace near one-sixth length of areola from cervical groove, where subequal to height (12.0 and 11.3 mm, respectively). Areola obliterated over most of its length and comprising 35.9% of CL and 42.5% of POCL. Rostrum with slender, straight margins converging from base to modestly delimited acumen; apex corneous, distinctly upturned and reaching ultimate podomere of antennular peduncle; dorsal surface concave with submarginal rows of punctations and others scattered in between. Subrostral ridge weak but visible in dorsal aspect to base of acumen. Postorbital ridge slender, well defined and relatively abruptly terminating anteriorly just posterior to margin of orbit. Cervical and branchiostegal spines absent. Suborbital angle obtuse and weak. Carapace punctate dorsally and weakly granulate-punctate laterally.

Abdomen subequal in length to carapace (25.6 and 25.3 mm, respectively); pleura small with subrounded margins; pleuron of 2 nd segment clearly overlapping that of 1 st. Telson divided and deeply incised laterally; caudolateral angle of cephalic section with pair of spines, more mesial one movable.

FIG. 25. Creaserinus crenastylus n. sp.: (a) lateral and (b) dorsal views of holotype. Specimen exhibits broadstriped phase.

Cephalic lobe of epistome subpentagonal, bearing a few punctations, margins slightly elevated and smooth ventrally; main body with weak fovea. Ventral surface of proximal podomere of antennule with spine at threefifths length. Antennal peduncle without spines, flagella with missing extremity reaches caudal margin of carapace. Antennal scale (Fig. 26f) reaching tip of acumen and ultimate podomere of antennular peduncle; lamella broadly rounded distomesially, broadest at three-fourths length and broader than thickened lateral part. Mandible with cephalic noncorneous, subtuberculiform molar process and caudal corneous, irregular molar process. Ventral surface of ischium of 3 rd maxilliped with long setae mesially and medium-length setae laterally; mesial half of ventral surface of basis bearing long setae.

FIG. 26. Creaserinus crenastylus n. sp.: (a) dorsal, (b) ventral, (c) lateral, and (d) mesial views of left chela (flipped in photo editor to appear as right chela); (e) tail; (f) antennal scale; (g) ventral view of merus, (h) proximal podomeres of pereiopods showing hook; and (i) annulus ventralis. a–h from holotype, i from allotype.

Left chela of cheliped (right missing tip of dactyl; Figs. 26a–d) 2.5 times as long as broad, strongly depressed; width of palm 1.7 times length of mesial margin. Latter bearing main row of 8 (right with 7) tubercles, bordered dorsolaterally by two rows of 6 (right with 6) and 1 slightly smaller tubercles, and ventrolaterally by row of 2 (right with 0). Dorsal surface of palm and fingers bearing setiferous punctations, those of dactyl and fixed finger much more distinct. Lateral margin of propodus costate along distal two-thirds, but broadly rounded proximally. Ventral surface punctate, with punctations more prominent on fingers, single tubercle on margin opposite base of dactyl with 6 more small ones situated proximolaterally to it. Long conspicuous setae present on proximal two-thirds of opposable margin of fixed finger. Dorsal and ventral surfaces of both fingers with well-defined ridges flanked by punctations. Opposable margin of fixed finger with row of 6 (right with 5) tubercles along proximal two-thirds, 2 nd and 3 rd from base largest, 5 th and 6 th situated more ventrally; single row of minute denticles extending from 3 rd tubercle to corneous tip of finger. Opposable margin of dactyl with prominent excision in proximal third; 2 tubercles borne within excision, a larger one at its distal extremity, and 4 (right with 3) more distal to excision; single row of minute denticles extending from large tubercle flanking excision to corneous tip of finger. Mesial margin of dactyl with main row of 14 tubercles flanked dorsolaterally by row of 8 (neither countable on right due to injury).

Carpus of cheliped 1.4 times as long as broad and 1.3 times as long as palm mesial margin; dorsal surface with longitudinal median trough, flanked with punctations; mesial surface tuberculate with large spine on distal margin; lateral and ventral surfaces punctate; ventral surface with large distomedian spine; ventromesial area tuberculate. Merus with 1 tubercle near dorsodistal extremity; mesial and lateral surfaces sparsely punctate; ventral surface (Fig. 26g) with mesial row of 13 tubercles (right with 13) and lateral row of 3 (right with 5), distal row absent. Ischium sparsely punctate with 1 tubercle ventromesially (right with 1).

FIG. 27. Creaserinus crenastylus n. sp.: (a) mesial, (c) ventral, and (e) lateral views of gonopod of holotype; and (b) mesial and (d) lateral views of gonopod of morphotype.

FIG. 28. Creaserinus crenastylus n. sp.: mesial views of gonopods of form I male paratypes. Each photo annotated with name of county where collected.

Second pereiopod bearing conspicuous long setae on dorsal and ventral margins of chela and carpus, and proximal half of ventral margin and dorsodistal extremity of merus, and dense mats of plumose setae on mesial faces of palm and carpus.

Hook (Fig. 26h) on ischium of 3 rd pereiopod simple, not reaching level of basioischial articulation, and not opposed by tubercle on corresponding basis. Coxa of 4 th pereiopod as in “Diagnosis.” Coxa of 5 th pereiopod lacking boss.

FIG. 29. Creaserinus crenastylus n. sp. type locality habitat.

Gonopod (Figs. 27a, c, e) almost reaching coxa of 3 rd pereiopod when abdomen flexed and obscured by setae extending from surrounding sternum; shaft of appendage straight, otherwise as in “Diagnosis.” Proximal podomere of uropod with both lobes bearing single small spines; endopod with distolateral spine and distinctly premarginal distomedian spine.

Allotypic female. Differing from holotype in nonsecondary sexual characters as follows: abdomen subequal in width to cephalothorax (12.6 and 12.4 mm, respectively); greatest width of carapace near one-half length of areola from cervical groove; areola comprising 37.6% of CL and 44.7% of POCL; weak branchiostegal tubercle present; abdomen slightly longer than carapace (27.4 and 25.8 mm, respectively); antennal scale reaching three-fourths length of acumen and midlength penultimate podomere of antennular peduncle; right chela of cheliped 2.1 times as long as broad; mesial margin of palm with 2 nd row of 3 small tubercles (left with 3) dorsolateral to main row, and irregular row of 6 (left with 6) tubercles ventrolaterally flanking it; opposable margin of fixed finger with row of 4 (left with 4) tubercles, 4 th situated more ventrally; mesial margin of dactyl with main row of 12 (left with 12) tubercles bordered dorsolaterally by two rows of 8 (left with 9) and 2 (left with 3) and ventrolaterally by row of 3 (left with 0); merus of cheliped with 7 (left with 6) tubercles near dorsodistal extremity, ventral surface with mesial row of 15 tubercles (left with 13) and lateral row of 5 (left with 5).

Annulus ventralis (Fig. 26i) 1.6 times as broad as long, cephalically fused to sternum. Caudal and lateral margins elevated (ventrally) and surrounding shallow, cephalic, caudodextrally-directed trough. Short sinus originating at caudomedian extremity, curving sinistrally 45°, then dextrally 180°, before terminating under dextral wall. Postannular sclerite subtriangular, one-third as wide and one-third as long as annulus. First pleopod present.

Morphotypic male, form II. Differing from holotype in following respects: areola comprising 38.1% of CL and 45.1% of POCL; branchiostegal spine rudimentary; abdomen slightly longer than carapace (26.5 and 24.9 mm, respectively); flagellum of antenna reaching 3 rd abdominal segment; width of palm of chela 1.5 times length of mesial margin; latter bearing main row of 7 (left with 8) tubercles bordered dorsolaterally by two rows of 5 (left with 6) and 4 (left with 3) successively smaller tubercles and ventrolaterally by row of 4 smaller tubercles (left with 4); ventral surface of propodus with group of 4 (left with 4) small tubercles situated proximolaterally to tubercle on margin opposite dactyl; opposable margin of fixed finger with row of 4 (left with 4) tubercles, 4 th situated more ventrally; mesial margin of dactyl with main row of 12 (left with 12) tubercles bordered dorsolaterally by two rows of 9 (left with 8) and 2 (left with 0) tubercles and ventrolaterally by row of 2 tubercles (left with 0); merus of cheliped with 5 tubercles (left with 4) near dorsodistal extremity, ventral surface with mesial row of 14 tubercles (14 on left) and lateral row of 5 (left with 7), distal row absent (left with 1 rudimentary tubercle); hook on ischium of 3 rd pereiopod and boss on coxa of 4 th pereiopod both reduced; gonopod (Figs. 27b, d) with central projection noncorneous, both processes more inflated, both recurved 120°.

Type locality. Farm to Market Road 3121, 0.6 km (0.4 mi) south junction with Texas Highway 21, Sabine County, Texas (31.43058, -93.78026). Roadside pool adjacent to very small stream in pine-hardwood forest (mostly pine). Water depth 8–25 cm at time of collection. Pool obviously dry much of time. See Fig. 29 .

Disposition of types. The holotype, allotype, and morphotype (nos. 1640955, 1640956, and 1640957, respectively) are deposited in the National Museum of Natural History , Smithsonian Institution. All paratypes remain in DPJ’s collection .

Size. Of 13 form I males for which measurements were made, carapace lengths range from 20.8 to 28.0 (x = 24.4) mm.

Range and specimens examined. Creaserinus crenastylus n. sp. has been found at five sites in two counties in Texas (Fig. 10), all of which are represented by at least one form I male. One site is represented by three samples in the phylogenetic analysis. In Texas, this species is confined to the Sabine River drainage in Sabine and Shelby counties. Based on Fig. 9q of Hobbs & Robison (1989:675), it is also found in DeSoto Parish, Louisiana .

Sabine: 31.4306, 93.7803, I, 2/29/08, 3/23/14, 3/28/15, DJ365, DJ608, DJ611; 31.5328, 93.8576, I, 2/29/08, 3/28/15; 31.5592, 93.8993, I, 3/28/15; 31.5826, 93.9446, I. Shelby: 31.7716, 93.9067, I, 3/15/08.

Variations. Variations in a number of key morphometrics and meristics may be found in Tables 3, 7, and 11–13. Additional variations not found in those tables are provided here. All are based on form I males, unless otherwise noted. The AL/CL ratio range is 35.7–39.8% (x = 37.8, s = 1.5, n = 13) and the AL/ POCL ratio range is 42.2–45.9% (x = 44.4, s = 1.4, n = 13). The rostral margins vary from straight to slightly convex, with a poorly- to well-delimited acumen. The rostrum L/W ratio ranges from 1.2 to 1.5 (x = 1.4, s = 0.1, n = 13). The ratio of the rostrum L to CL ranges from 18.1 to 20.8% (x = 19.1, s = 1.0, n = 13). The branchiostegal spine varies from small to absent. The suborbital angle is usually small and obtuse, but occasionally obsolete. The shape of the anterior lobe of the epistome ranges from subtriangular to subsemicircular to subelliptical to subtrapezoidal. The caudolateral angle of cephalic section of telson typically bears 2 spines with the mesial one movable, but one individual bore 4 spines on one side and 3 on the other with all but the lateralmost spine on each side movable. Notable variations in the numbers of tubercles on the cheliped include the following: 10–14 (x = 12.8, s = 1.1, n = 16) in the main row on the mesial margin of the dactyl, 7–10 (x = 8.3, s = 0.9, n = 16) and 0–3 (x = 1.1, s = 1.2, n = 9) in the 2 rows dorsolaterally bordering it, and 0–4 (x = 1.0, s = 1.3, n = 9) in the row ventrolaterally bordering it; 6–10 (x = 7.6, s = 0.9, n = 17) in the main row of the palm’s mesial margin, 5–8 (x = 6.6, s = 0.8, n = 17) and 0–6 (x = 2.8, s = 2.3, n = 9) in 2 rows dorsolaterally flanking it, and 2–5 (x = 3.2, s = 1.0, n = 9) in the row ventrolaterally bordering it; 12–16 (x = 13.9, s = 1.0, n = 15) in the ventromesial row of the merus, and 3–7 (x = 4.9, s = 1.3, n = 15) in the ventrolateral row; and 0–4 (x = 2.1, s = 1.2, n = 15) in the ventromesial row of the ischium. Figure 28 illustrates variation in the form I male gonopod. The MP caudal offset ranges from distinctly greater than (Fig. 28j) to slightly less than (Fig. 28f) that of the CP. The tips of the processes are usually distinctly separate, but occasionally overlapping (Fig. 28c). The subapical notch is slightly better developed in some specimens (Figs. 28a, f) than in others (Figs. 28j, l). The annulus ventralis never occurs as a mirrored image of that of the allotype.

Life history notes. Seasonal collection data of Creaserinus crenastylus n. sp. ( Table 26 ) is very limited but exhibit patterns not obviously inconsistent with that of the genus Creaserinus as a whole. Refer to its “Life history notes” for discussion.

Ecological notes. This crayfish has been found in pine-hardwood forest and woodland/grassland mosaic, in small roadside ephemeral streams, marshes, pools, and ditches. All waters are temporary. No burrows of this species have been excavated.

Etymology. Crena (L.) = notch + stylos (G.) = pillar or column, alluding to the notch-bearing central projection characteristic of the gonopod of form I males of this species.

Crayfish associates. Collected with Creaserinus crenastylus n. sp. were the following three crayfish taxa: Faxonella beyeri (n = 2, 40.0%), Procambarus (Ortmannicus) acutus (n = 2, 40.0%), and Procambarus (Girardiella) kensleyi (n = 1, 20.0%).