Creaserinus brevistylus, 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 : 34-42

Creaserinus brevistylus n. sp.

Figs. 3, 5, 6d, j, 7a–e, 9–17, Tables 1–6 , 20, 21

Fallicambarus (Creaserinus) fodiens .— Hobbs & Robison, 1989:672, Fig. 9j [in part].— Hobbs, 1990:575 [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, lacking subapical notch, recurved 115–150° to axis of shaft, with distal part directed caudoproximally with tip never crossing central projection of corresponding gonopod, and base not inclined laterally, length 26.6– 31.5% (x = 28.8, s = 1.3, n = 46) of total gonopod length. Mesial process noncorneous, recurved approximately 105– 125° to axis of shaft, proximal half not strongly inflated. Proximal gap between processes usually present. Uropodal endopod with distolateral spine; distomedian spine premarginal (rarely reaching margin). Telson divided with spine on anterolateral flank of suture. Function 6 positive when b refers to Creaserinus brevistylus n. sp. and a refers to any of other five Texas species (refer to Tables 2–6). Distribution restricted to Sabine River and Neches River drainages north of Hardin County. 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. 13a, b). Abdomen slightly narrower that cephalothorax (12.1 and 14.3 mm, respectively). Greatest width of carapace near one-sixth length of areola from cervical groove, where slightly greater than height (14.3 and 13.6 mm, respectively).Areola obliterated over most of its length and comprising 38.6% of CL and 45.9% of POCL. Rostrum with slender, convex margins converging from base to poorly delimited acumen; apex corneous, distinctly upturned and reaching one-fourth length of ultimate podomere of antennular peduncle; dorsal surface concave with submarginal rows of punctations and few, very weak others widely 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 spine absent. Weak branchiostegal tubercle present. Suborbital angle obtuse and weak. Carapace punctate dorsally and weakly granulate-punctate laterally.

Abdomen equal in length to carapace (29.2 mm); 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.

Cephalic lobe of epistome subsemicircular and emarginate, bearing a few barely evident punctations, margins slightly elevated and smooth ventrally; main body lacking fovea. Ventral surface of proximal podomere of antennule with spine at two-thirds length. Antennal peduncle without spines, flagella missing. Antennal scale (Fig. 14f) nearly reaching tip of acumen and reaching ultimate podomere of antennular peduncle; lamella broadly rounded distomesially, broadest at four-fifths 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, remainder with medium-length setae; mesial half of ventral surface of basis bearing long setae.

Right chela of cheliped (Figs. 14a–d) 2.2 times as long as broad, strongly depressed; width of palm 1.9 times length of mesial margin. Latter bearing main row of 6 (left with 6) tubercles flanked dorsolaterally by group of 5 (left with 6) slightly smaller tubercles and ventrolaterally by row of 2 barely discernable ones (1 large on left). 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 two more situated proximolaterally to it. Long conspicuous setae present on proximal half 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 5 tubercles along proximal two-thirds, 2 nd and 3 rd from base largest, 5 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 and a larger one at its distal extremity, 7 (left with 5) more tubercles distal to excision; single row of minute denticles extending from 2 nd distalmost tubercle to corneous tip of finger. Mesial margin of dactyl with main row of 11 (left with 12) tubercles bordered dorsolaterally by row of 7 (left with 9) tubercles and ventrolaterally by row of 2 much smaller ones (left with 3).

Carpus of cheliped 1.4 times as long as broad and 1.5 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 and smaller spine at ventrolateral condyle. Merus with 4 tubercles near dorsodistal extremity; mesial and lateral surfaces sparsely punctate; ventral surface (Fig. 14g) with mesial row of 13 tubercles (left with 14) and lateral row of 4 (left with 4), distal row absent. Ischium sparsely punctate with ventromesial row of 3 tubercles (left with 4).

FIG. 13. Creaserinus brevistylus n. sp.: (a) lateral and (b) dorsal views of holotype. Specimen exhibits broadstriped phase.

FIG. 14. Creaserinus brevistylus n. sp.: (a) dorsal, (b) ventral, (c) lateral, and (d) mesial views of 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.

Second pereiopod bearing conspicuous long setae on dorsal and ventral margins of chela and carpus, and ventral margin of merus, and mats of modestly developed plumose setae on mesial faces of palm and carpus.

Hook (Fig. 14h) on ischium of 3 rd pereiopod simple, almost 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.

Gonopod (Figs. 15a, c, e) almost reaching coxa of 3 rd pereiopod when abdomen flexed and substantially 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: areola comprising 38.1% of CL and 44.6% of POCL; branchiostegal tubercle absent; abdomen slightly longer than carapace (32.3 and 30.4 mm, respectively); caudolateral angle of cephalic section of telson with 3 spines, more mesial 2 movable; cephalic lobe of epistome with median prominence, main body with fovea; antennal scale reaching tip of acumen and midlength ultimate podomere of antennular peduncle; right chela of cheliped 2.1 times as long as broad; palm mesial margin bearing main row of 7 (left with 5) tubercles, bordered dorsolaterally by group of 5 (left with 5) slightly smaller tubercles, and ventrolaterally by row of 2 smaller tubercles (left with 1); group of 3 smaller tubercles situated proximolaterally to tubercle on ventral margin of propodus opposite dactyl; opposable margin of fixed finger with row of 6 tubercles along proximal two-thirds, 3 rd and 4 th from base largest, 6 th situated more ventrally; opposable margin of dactyl with 3 tubercles in excision; 4 (left with 5) tubercles distal to main tubercle delimiting excision; mesial margin of dactyl with main row of 10 (left with 11) tubercles bordered dorsolaterally by row of 5 (left with 4) tubercles and ventrolaterally by row of 2 (left with 0); merus of cheliped with 6 (left with 9) tubercles near dorsodistal extremity, ventral surface with mesial row of 11 tubercles (left with 12), lateral row of 5 (left with 5), and distal row of 1 (left with 1); ischium of cheliped with ventromesial row of 3 tubercles (left with 2); second pereiopod lacking plumose setae on mesial faces of palm and carpus.

Annulus ventralis (Fig. 14i) 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 dextrally 120°, before terminating under dextral wall. Extending from termination of sinus is narrow, poorly calcified lineation curving sinistrally then dextrally before terminating at cephalomedian extremity. Postannular sclerite subtriangular, half as wide and less than half as long as annulus. First pleopod present.

Morphotypic male, form II. Differing from holotype in following respects: areola comprising 37.9% of CL and 45.1% of POCL; suborbital angle nearly obsolete; caudolateral angle of cephalic section of telson with 3 spines, more mesial 2 movable; cephalic lobe of epistome not emarginate, main body with weak fovea; flagellum of antenna reaching midlength cephalic section of telson; antennal scale almost reaching tip of acumen; right chela of cheliped 2.1 times as long as broad; ventral surface of propodus with row of 4 weak tubercles positioned proximolaterally to single tubercle on margin opposite dactyl; opposable margin of fixed finger with row of 6 tubercles along proximal two-thirds, 3 rd and 4 th from base (2 nd and 3 rd on left) largest, 6 th situated more ventrally; opposable margin of right dactyl with 6 tubercles distal to large tubercle delimiting excision; merus of cheliped with 5 (left with 8) tubercles near dorsodistal extremity, ventral surface with mesial row of 16 tubercles (left with 14), lateral row of 5 (left with 5), and distal row of 1 (left with 1); hook on ischium of 3 rd pereiopod and boss on coxa of 4 th pereiopod both reduced; gonopod (Figs. 15b, d) with central projection noncorneous, both processes more inflated, central projection recurved 90°, mesial process 120°.

Type locality. Farm to Market Road 705, 1.1 km (0.7 mi) south junction with Farm to Market Road 300-3, San Augustine County, Texas (31.19671, -94.13922). Roadside ditch in pine forest. Water 15 cm deep at time of collection. See Fig. 17 .

Disposition of types. The holotype, allotype, and morphotype (nos. 1640949, 1640950, and 1640951, respectively) are deposited in the National Museum of Natural History, Smithsonian Institution.The paratypes remain in DPJ’s collection, which is slated for eventual donation to the North Carolina Museum of Natural Sciences .

Size. Of 46 form I males for which measurements were made, carapace lengths range from 22.9 to 33.7 (x = 27.0) mm.

Range and specimens examined. Creaserinus brevistylus n. sp. has been found at 53 sites in 14 Texas counties (Fig. 10), of which 42 (79.2%) are represented by at least one form I male and 27 (50.9%) are represented in the molecular phylogeny. The species is confined to the Sabine River and Neches River drainages mostly north of the Kisatchie Wold. This species with little doubt also occurs in neighboring Louisiana; however, no records are available to definitively prove this.

Angelina: 31.1112, 94.2883, 3/2/08, 3/27/15. Harrison: 32.3771, 94.3290, I, 4/10/15; 32.3893, 94.4454, I, 4/12/15. Jasper: 30.8529, 94.1700, I, 3/21/14. Nacogdoches: 31.5863, 94.8303, I, 6/16/12; 31.7164, 94.4494, I, 3/29/13; 31.4977, 94.8099, I. Panola: 32.0822, 94.2546, I, 2/16/13; 32.2170, 94.2404; 32.1948, 94.3406, I; 32.1221, 94.2918, 5/2/14; 32.1244, 94.2074, I; 32.2319, 94.0859, I; 32.1209, 94.3466, I; 32.0684, 94.3067, I; 32.0496, 94.3763; 32.0407, 94.5626, I; 32.1935, 94.4603; 32.2334, 94.3808, I; 32.3136, 94.3547, I, 4/10/15; 32.2799, 94.4406, I, 4/12/15. Rains: 32.7820, 95.7969, 6/13/14. Rusk: 32.0342, 94.6216, I, 5/2/14. Sabine: 31.2065, 93.7503, I, 3/23/14, 3/28/15; 31.2960, 93.8438, I, 3/23/14; 31.4298, 93.9418, I; 31.4125, 93.9981, I; 31.2275, 93.8442, I, 3/28/15; 31.2498, 93.9109; 31.2439, 93.9754; 31.3791, 93.8907. San Augustine: 31.2901, 94.2335, I, 3/1/08, 3/29/15; 31.2728, 94.1302, I, 2/14/10, 3/29/15; 31.1967, 94.1392, I; 31.2904, 94.2804, 2/15/13, 3/29/15; 31.3301, 94.2810; 31.2524, 94.3061, I, 3/29/15; 31.3481, 94.0883; 31.3062, 94.0864, I. Shelby: 31.7664, 94.1866, I, 3/15/08; 31.7691, 94.0897, I; 31.9675, 94.0626, I; 31.9558, 94.1959, I; 31.9372, 94.3704, I; 31.8851, 94.0937, 2/15/13; 31.8676, 94.2092, I, 2/16/13. Smith: 32.5957, 95.3930, I, 4/4/14. Tyler: 30.8605, 94.2392, I, 3/21/14. Van Zandt: 32.7194, 95.6371, I, 6/13/14; 32.6852, 95.8278. Wood: 32.6303, 95.3462, I, 4/4/14; 32.6183, 95.4861, I; 32.6741, 95.5700, I.

FIG. 15. Creaserinus brevistylus 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. 16. Creaserinus brevistylus n. sp.: mesial views of gonopods of form I male paratypes. Each photo annotated with name of county where collected.

FIG. 17. Creaserinus brevistylus n. sp. type locality habitat.

Variations. Variations in a number of key morphometrics and meristics may be found in Tables 2–6. Additional variations not found in those tables are provided here. All are based on form I males, unless otherwise noted. The rostral margins vary from straight to slightly convex, and parallel to distinctly converging. In one individual, the rostrum was much more strongly deflected ventrally than the norm. The acumen varies from distinctly delimited to not obviously delimited. The rostrum L/W ratio ranges from 1.1 to 1.7 (x = 1.4, s = 0.1, n = 44), while the ratio of the rostrum L to CL ranges from 16.2 to 20.0% (x = 18.7, s = 1.2, n = 44). The branchiostegal spine varies from small and acute to absent. The suborbital angle varies from small, obtuse, and distinctly evident to obsolete. The anterior lobe of the epistome ranges in shape from subsemicircular to subtriangular to subtrapezoidal. Considerable variation occurs in the number of tubercles on the various podomeres of the cheliped: 8–16 (x = 12.0, s = 1.4, n = 76) in the main row on the dactyl’s mesial margin, 4–10 (x = 7.0, s = 1.2, n = 76) and 0–2 (x = 0.3, s = 0.7, n = 10) in 2 rows dorsolaterally flanking the main row, 0–4 (x = 0.6, s = 1.3, n = 10) in the row ventrolaterally flanking the main row; 6–8 (x = 7.0, s = 0.8, n = 27) in the main row on the palm’s mesial margin, 3–6 (x = 5.1, s = 1.0, n = 27) and 1–4 (x = 2.2, s = 0.9, n = 10) in the rows dorsolaterally and ventrolaterally abutting it; 11–15 (x = 12.9, s = 1.2, n = 34) in the ventromesial row of the merus, and 2–7 (x = 4.7, s = 1.2, n = 37) in the ventrolateral row; and 0–5 (x = 2.2, s = 1.3, n = 36) in the ventromesial row of the ischium. The distomedian spine of the uropodal endopod varies from distinctly premarginal to reaching the margin. Figure 16 illustrates variation in the form I male gonopod. The angle of recurvature of the CP ranges from 115° (Fig. 16a) to 150° (Fig. 16r), while that of the MP ranges from 105° (Fig. 16b) to 125° (Fig. 16r). The processes are usually distinctly separate along their entire lengths (Fig. 16g), but the separation may be absent near midlength (Fig. 16h). The MP varies from acuminate (Fig. 16t) to blunt (Fig. 16a), and the tip varies from slightly procurved (Fig. 16u) to slightly recurved (Fig. 16w). The MP caudal extension beyond the CP ranges from distinct (Fig. 16f) to very slight (Fig. 16s). The gonopod shaft is usually slightly caudally arched (Fig. 16a) but is occasionally unarched (Fig. 16u). The annulus ventralis never occurs as a mirrored image of that of the allotype.

Life history notes. Seasonal collection data of Creaserinus brevistylus n. sp. ( Table 21 ) exhibit patterns consistent with that of the genus Creaserinus as a whole. Refer to its “Life history notes” for discussion. Neither ovigerous females nor females carrying young have been found.

Ecological notes. This crayfish has been found in pine woods, deciduous woods, open pasture, and semi-urban habitats. It is frequently associated with bottomlands of streams and rivers and has been collected from temporary waters of ditches, pools, swales, and shallow marshes. Among its crayfish associates, it prefers less temporary waters than the extremely temporary ones dominated by juveniles of Fallicambarus wallsi Johnson, 2011a , but more temporary waters than all other non- Creaserinus crayfish associates occurring in open waters. Water bodies may contain hydrophytic or nonhydrophytic vegetation or may be devoid of vegetation. Soils include readily burrowable clay and silt, while areas of ironstone which are widespread in the range of this species are generally avoided. Of burrows excavated for this species, several had simple vertical shafts with single entrances, and one was relatively complex with multiple tunnels and entrances.

Etymology. Brevis (L.) = short + stylos (G.) = pillar or column, alluding to the short central projection characteristic of the gonopod of males of this species.

Crayfish associates. Collected with Creaserinus brevistylus n. sp. were the following 11 crayfish taxa: Faxonella beyeri ( Penn, 1950) (n = 27, 50.9%), Procambarus (Ortmannicus) acutus ( Girard, 1852) (n = 24, 45.3%), Procambarus (Girardiella) kensleyi Hobbs, 1990 (n = 13, 24.5%), Procambarus (Girardiella) curdi Reimer, 1975 (n = 5, 9.4%), Cambarellus (Pandicambarus) puer Hobbs, 1945 (n = 4, 7.5%), Lacunicambarus ludovicianus ( Faxon, 1884) (n = 4, 7.5%), Creaserinus limulus n. sp. (n = 4, 7.5%), Cambarellus (Pandicambarus) shufeldtii ( Faxon, 1884) (n = 3, 5.7%), Fallicambarus wallsi (n = 3, 5.7%), Procambarus (Scapulicambarus) clarkii ( Girard, 1852) (n = 2, 3.8%), and Procambarus (Girardiella) simulans ( Faxon, 1884) (n = 2, 3.8%). Notable is the cooccurrence at 4 sites with its congener, Creaserinus limulus n. sp. Additionally it seems very likely that it also occurs with both C. crenastylus n. sp. and C. clausus n. sp. as both have been found in close proximity to this species in the same drainage system (Fig. 10).