Cambarus (Jugicambarus) adustus Thoma, Jr, Stocker & Loughman, 2016, new species

Cambarus (Jugicambarus) adustus, new species

Figures 2–4, Table 1

Cambarus aff. dubius: Loughman, Thoma, Fetzner and Stocker, 2015:534 [in part].

Diagnosis. Pigmented; eyes not reduced. Rostrum with margins slightly convergent, moderately thickened, without marginal spines or tubercles, lacking median carina, slightly excavated, and angled near end at slightly less than 90° to a well-defined acumen. Carapace vaulted, subovate in cross-sectional view, without cervical spines. Branchiostegal tubercles moderately developed. Suborbital angle obtuse to acute. Postorbital ridges developed, never ending in distinct spines or tubercles. Areola open, length 6.9 to 17.9 times width (x = 12.6, n = 27), constituting, in adults, 28.1 to 42.5% (x = 40.6%, n = 27) of entire carapace length, with room for 2 or 3 rows of punctuations in narrowest part. Antennal scale 1.4 to 2.8 times as long as wide (x = 2.41, n = 27), usually broadest at mid-point. Mesial palm of chelae with two rows of tubercles. First row consisting of 5–8, second row of 2–7 well developed tubercles; first row cristiform. No tufts of elongate setae at base of opposable propodus. Opposable margin of propodus with four enlarged tubercles on basal half consisting, from base, of two smaller tubercles, an enlarged tubercle, a space, and a sharply pointed forth tubercle; denticles extending on average 69.0% (n = 27) of distal length. Opposable margin of dactyl from base with one enlarged tubercle, followed by two smaller tubercles, and then one enlarged tubercle, all on basal half; denticles extending on average 51.8% of distal length. Palm length to dactyl length ratio averaging 1.8. Strong dorsomedian longitudinal ridges on dactyl and propodus. Moderate to weak dorsolateral impression at base of propodus. Carpus with one large tubercle on mesial margin, just distal of midpoint, usually with two smaller tubercles proximal to base; row of three to four small tubercles dorsal to carpal tubercle. First pleopods of form I male adjoining at bases, shafts with convexity near mid length of cephalic surface; terminal elements consisting of a tapering, distally pointed central projection with a subapical notch, and equal in length to mesial process. Mesial process conically shaped at base and tapering to distal point(s). Both processes recurved at 90°. Mesial processes deflected slightly lateral. Caudal knob present. Hooks on ischium of third pereiopods only, not opposed by tubercle on coxa. Female with asymmetrical annulus ventralis formed by two hardened caudal parts, one curved in a C shape the other a straight, rounded segment forming a flange that projects under the C-shaped portion creating a fossa. Cephalic half of annulus ventralis not sclerotized. Postannular sclerite a symmetrical bar shape, greatest height in center.

Holotypic male, Form I. (Fig. 2 A, B, C, D, E, H, J, K & Fig. 3). Eyes pigmented, diameter 37.2% of width of rostrum at eyes. Body vaulted, subovate (Fig. 2 J), width equal to depth (Fig. 2 A). Abdomen narrower than cephalothorax; maximum width of carapace slightly greater than depth at caudodorsal margin of cervical groove. Areola narrow (1.1 mm) with two punctuations across narrowest part, length comprising 41.4% of total carapace length. Rostrum slightly curved downward distally with slightly convergent, thickened margins and a slightly less than 90° angle delimiting acumen, anterior tip upturned, not reaching to base of ultimate podomere of antennular peduncle; dorsal surface of rostrum slightly excavate with few punctuations, mostly on basal half. Subrostral ridge moderately developed. Postorbital ridge well developed, grooved dorsolaterally, and ending cephalically without tubercle, spine or corneous portion. Suborbital angle obtuse; branchiostegal spine small. Cervical spine absent. Hepatic and branchiostegal regions with small tubercles. Lateral carapace with granular tubercles, dorsally punctate. Abdomen slightly shorter than carapace, pleura short, rounded caudoventrally. Cephalic section of telson with two spines in caudolateral corners. Proximal podomere of uropod with weak distal spine on mesial lobe; mesial ramus of uropod with median rib ending distally as weak distomedian spine not overreaching margin of ramus.

Cephalomedian lobe of epistome (Fig. 2 D) pentagonal in shape with level margins, small setae; main body with shallow fovea; epistomal zygoma moderately arched. Ventral surface of antennal peduncle’s proximal podomere without spine at base of distal third. Antennal peduncle without spines; antennal scale (Fig. 2 H) 2.4 times as long as wide, broadest at midpoint, distal mesial border rounded, proximal border straight; distal spine moderate, not reaching distal extremity of antennular peduncle. Ischium of third maxilliped with abundant flexible setae; mesial margin with 20 teeth, numbers 1, 4, 6, 8 and 11 from distal end larger than adjacent teeth.

Length of right chela (Fig. 2 K) 76% that of carapace; width 49% of chela length; palm length 36% of chela length; dactyl length 1.7 times palm length. Dorsal surface of palm covered with punctations, mesial margin with two rows of tubercles, first row seven, second row five; ventral surface mostly smooth, one low tubercle on articular rim opposite base of dactyl; lateral surface of chela slightly costate. Both fingers of chela with welldefined submedian dorsal ridges; opposable margin of fixed finger with row of four tubercles (third from base enlarged), gap between third and fourth tubercle, denticles extending distally from third tubercle over 71% of opposable margin of propodus. Opposable margin of dactyl with row of four tubercles along proximal half, first and fourth enlarged; single row of minute denticles extending distally from tubercle two over 61.9% of dactyl length; mesial surface of dactyl with three basal tubercles.

Carpus of cheliped with distinct dorsal furrow; mesial surface with one large spiniform tubercle subtended by one small tubercle proximally, third small tubercle at proximal edge of carpus; ventral surface with small tubercle on distal articular rim, and small fifth tubercle positioned between largest mesial tubercle and articular rim tubercle. Merus with two premarginal, slightly spiniform, tubercles dorsally, ventromesial row of ten spiniform tubercles slightly increasing in size distally, ventrolateral row of nine. Ventral ridge of ischium without tubercles. Ischium of third pereiopods (Fig. 2 E) with strong hook extending proximally over basioischial articulation, not opposed by tubercles on basis. Coxa of fourth pereiopods (Fig. 2 E) with vertically disposed caudomesial boss; that of fifth pereiopod lacking boss, its ventral membrane setiferous.

First pleopods adjoining at base, just reaching coxae of third pereiopods when abdomen flexed; central projection (Fig. 2 B, C) long, tapering with subapical notch, angled at 90°, shorter than mesial process; mesial process conical at base and tapered apically, directed caudolaterally, bent greater than 90°, terminating in single point, slightly defined caudal knob. Distal margin of proximal segment of lateral ramus of right uropod having fourteen small spines displayed distally, one larger, movable penultimate spine at lateral edge, median spine of mesial uropod ramus small, not overhanging distal margin.

Allotypic female. Other than secondary sexual characters, differing from holotype in following respects: right chela 69% carapace length; dactyl of pereiopod I 1.75 times length of palm; palm of chela with two rows of seven tubercles in first row and five in second; eye diameter 36% of rostrum width at eyes; denticles extending distally over 64% of inner margin of propodus, denticles extending distally over 58.4% of dactyl length. Annulus ventralis (Fig. 2 I) sclerotized on caudal margin, moderately embedded in V-shaped sternum, asymmetrical in shape, formed by two hardened caudal parts, right curved in a weak C shape, left a straighter, rounded segment with a flange projecting under C-shaped portion and forming a fossa. Cephalic half of annulus ventralis not sclerotized. Postannular sclerite a symmetrical oval shape with a distal indentation, greatest height in center.

Morphotypic male, Form II. Differing from holotype in following respects: palm of chela with two rows of tubercles (first row = 7, second = 4); areola length 42.3% of carapace length; areola 11.7 times as long as wide; antennal scale 2.64 times as long as wide; right chelae 60% of carapace length; palm length 35% of chela length; eye diameter 48.7% of rostral width at eyes; merus with row of five ventrolateral spines; central projection of first pleopod (Fig. 2 F, G) non corneous and blunt, equal in length to mesial process. Hook on ischium of third pereiopod smaller, not overhanging basioischial articulation. Distal margin of proximal segment of lateral ramus of right uropod having 16 spines displayed distally.

Type locality. Holotype, morphotype, and allotype collected from roadside ditch serving as a tributary to Big Branch of Salt Lick Creek adjacent KY Rt. 898 just N of Hatcher Branch, 4.67 km SW of Charters, 3.60 km NE of Glen Springs, (38.53930, -83.46565, WGS84), Lewis County, Kentucky. The holotype and allotype were both collected on 16 October 2014; morphotype was collected on 12 June 2013.

Disposition of types. The holotype, allotype, and morphotype are in the collection of the National Museum of Natural History (USNM 1407169, 1407170, and 1407171 respectively), Suitland, Maryland along with paratypes (USNM 1409733). Additional paratypes are housed in the Cleveland Museum of Natural History (CMNH 1179) and Carnegie Museum of Natural History (CM Acc. 38597).

Range and specimens examined. This species has only been found in Lewis County, Kentucky in the Quicks Run, Salt Lick Creek and the eastern edge of Cabin Creek basins. Adjacent areas in Kentucky and Ohio have been searched but no other populations have been found. Taylor and Schuster (2004) did not report C. dubius from Lewis County, KY. Their closest record was a single site reported from Rowan County, KY in the Licking River basin.

KENTUCKY: Lewis County: 1) CMNH 1179 —ditch adjacent KY Rt. 989, tributary to Big Branch of Salt Lick Creek of Ohio River, 0.95 km W of Glen Springs, 18.52 km SW of Vanceburg, (38.50859, -83.49575, WGS84), Roger F. Thoma (RFT) and Jim Grow (JG), 2 MI, 1 MII, 12 F, 3 M juv, 3 F juv, 31 August 2013; 2) USNM 1407169, 1407170, 1407171 [Holotype, Allotype, Morphotype], CM Acc. 38597 [Paratypes]—roadside ditch tributary to Big Branch of Salt Lick Creek adjacent KY Rt. 898, 4.67 km SW of Charters, 3.60 km NE of Glen Springs, (38.53930, -83.46565, WGS84), RFT and G. Whitney Stocker (GWS), 1 MI, 1 MII, 1 F, 1 M juv, 1 F juv, 12 June 2013; 3) CMNH 1180 —roadside ditch in Manley Hollow of Fry Branch of East Fork Cabin Creek adjacent Manley Hollow Road, 16.27 km W of Vanceburg, 12.09 km SE of Manchester, (38.61050, -83.50592, WGS84), RFT & GWS, 1 MI, 1 F, 12 June 2013; 4) CMNH 1182 —ditch adjacent Quicks Run Road, 3.67 km W of Queens, 6.97 km NE of Tollesboro, (38.625357, -83.479688, WGS84), RFT, 1 MI, 1 F, 1 M juv, 2 F juv, 12 May 2011; 5) CMNH 1183 —roadside ditch tributary to Quicks Creek adjacent Quicks Creek Road at Muses Church and cemetery, 6.99 km SSE of Concord, 13.76 km SE of Manchester, (38.62527, -83.47250, WGS84), RFT & GWS, 2 MI, 3 MII, 12 June 2013; 6) CMNH 1181 —ditch adjacent Quicks Run Road and graveyard/church, 3.06 km W of Queens, 7.25 km NE of Tollesboro, (38.625246, -83.472327, WGS84), RFT, 2 MII, 2 M juv, 1 F juv, 1 body part, 12 May 2011; 7) USNM 1409733 — Salt Lick Creek adjacent Salt Lick Road at #3073 Salt Lick Road, 3.6 km NE of Glen Springs, 14.7 km SW of Vanceburg, (38.539320, -83.465670, WGS84), RFT, JG, Max Luehrs (ML), Mitch Farley (MF) 7 MI, 1 MII, 4 F, 16-Oct-15; 8) CMNH 1184 —roadside ditch adjacent Big Branch of Salt Lick Creek and KY Rt 989, 1.12 km WSW of Glen Springs, 18.59 km SW of Vanceburg, (38.508790, -83.496560, WGS84), RFT, JG, ML, MF, 16 October 2015. No material collected by Jezerinac and Stocked was available for examination.

Conservation status. Cambarus (J.) adustus , new species, is narrowly distributed, with a current extent of occurrence of 19.5 km 2 in Lewis County, Kentucky. It is best classified as Endangered following Taylor et al. (2007), Endangered (B2ab(iii), ver. 3-1) using IUCN criteria (IUCN 2001), G1 using NatureServe. It should be listed as S1 by the state of Kentucky, and Endangered by the USFWS.

Color notes. All specimens observed have been a concolorous brown (Fig. 4). Tubercles on the opposable margins of the chelae fingers are cream-yellow. The tips of chelae fingers can be orange.

Variation. No geographic variation has been identified in the highly limited range of this species. Within population variation consist primarily of ontogenetic changes and sexual dimorphism.

Size. The three largest individuals were female, with the largest female having a carapace length of 45.9 mm. Mature form I males average TCL was 37.0 mm (34.60–39.8 mm), form II males average TCL was 32.3 mm (27.2–35.4 mm), and females TCL averaged 37.0 mm (30.0– 45.2 mm) carapace length.

Life history. Collections have been made in May, June, August, September, and October. First form males, second form males, and females have been observed in all months sampled. No ovigerous females or young-ofyear have been observed.

Crayfish associates. Cambarus thomai and Cambarus ortmanni are found burrowing in adjacent areas. In streams of the area there is a member of the Orconectes subgenus Procericambarus present. It is not clear if these populations represent an undescribed species or are just a geographic variant of Orconectes raymondi Thoma and Stocker 2009.

Relationships. Cambarus adustus is assigned to the subgenus Jugicambarus based on the presence of a cristiform row of tubercles on the mesial margin of the chelae. It appears to be most closely related to C. dubius, C. pauleyi, and other members of the C. aff. dubius complex. It is hypothesized that the species had become established in the preglacial Portsmouth River prior to the onset of the Quaternary. Cambarus adustus displays a caudal knob similar to, but smaller than, Cambarus bouchardi Hobbs 1970. This character state is not thought to reflect a close relationship between the two species.

Comparisons. Within the genus Cambarus, C. (J.) adustus new species, falls within the group of species with a vaulted carapace. Almost all members of this morphological group display dramatic color patterns involving bright reds and blues in life. In contrast, Cambarus adustus is all brown. When specimens are keyed using morphological characters, the couplets lead to C. dubius (Thoma 2016). Both species have a truncated rostrum, narrow areola, cristiform palmer tubercles, slightly vertically rotated chelae, and a vaulted carapace. It is easily distinguished from C. dubius in several ways. The slight caudal knob on the MI gonopod is not present in C. dubius or any closely related taxa/forms (see Loughman et al. 2015), a lack of red and blue coloration in C. adustus is a distinguishing characteristic in live animals, and the lateral carapace of C. adustus is more strongly granular with many small tubercles, while C. dubius tuberculation is much reduced.

A superficial similarity exist between C. adustus and C. ortmanni. Both are primary burrowers and both are brown. Cambarus ortmanni lacks a cristiform row of tubercles on the chelae palm, has only one row of palmer tubercles, has a very narrow areola with only one row of punctations, and a much reduced suborbital angle being almost obsolete, as opposed to a more obtuse suborbital angle in C. adustus. Two other brown colored primary burrowers (Cambarus nodosus Bouchard and Hobbs 1976 and Cambarus causeyi Riemer 1966) are found in the subgenus Jugicambarus. Cambarus causeyi differs in the abundant setae found on the chelae. Cambarus nodosus differs in its dramatically enlarged central projection and mesial process of the MI gonopod and a lack of small tubercles on the lateral surface of the posterior thorax.

Within the subgenus Jugicambarus, the group of stream dwelling species related to C. distans (Cambarus bouchardi, Cambarus crinipes Bouchard 1973, Cambarus obeyensis Hobbs and Shoup 1947, Cambarus tuckasegee Cooper and Schofield 2002, Cambarus unestami Hobbs and Hall 1969, Cambarus parvoculus Hobbs and Shoup 1947, and Cambarus jezerinaci Thoma 2000) all differ in the shape of their carapace, which is dorsoventrally compressed, as opposed to laterally compressed (vaulted).

Etymology. The species epithet (adustus = L. brown) is chosen to recognize the overall coloration of this species. The suggested vernacular name is Dusky Mudbug.