Parastacus caeruleodactylus Ribeiro & Araujo

Ribeiro, Felipe Bezerra, Buckup, Ludwig, Gomes, Kelly Martinez & Araujo, Paula Beatriz, 2016, Two new species of South American freshwater crayfish genus Parastacus Huxley, 1879 (Crustacea: Decapoda: Parastacidae), Zootaxa 4158 (3), pp. 301-324 : 311-317

Parastacus caeruleodactylus Ribeiro & Araujo sp. nov.

( Figs. 2 , 6–9 )

Zoobank: urn:lsid:zoobank.org:act:1BD9ED38-24DA-4C6B-9981-5497EC81BF3A

Holotype. Ƌ, Brazil, Rio Grande do Sul, Morrinhos do Sul (29°17’13.7”S; 49°54’53.42”W), 12/XII/2013, col. F.B. Ribeiro & K.M. Gomes ( MZUSP 34287 )

Paratypes. 1: Brazil, Rio Grande do Sul—one ♀, same data as holotype ( UFRGS 5931 ) ; 2: one ♀, same data as holotype ( UFRGS 5932 ) ; 3: one Ƌ, Dom Pedro de Alcântara, RPPN Mata do Professor Baptista (29°23’06”S; 49°50’20”W), 16/IV/2014, col. D.C. Kenne & K.M. Gomes ( UFRGS 5934 ) ; 3: one Ƌ, Dom Pedro de Alcântara, RPPN Mata do Professor Baptista (29°23’06”S; 49°50’20”W), 16/IV/2014, col. D.C. Kenne & K.M. Gomes ( UFRGS 5935 ) ; 5–6: one Ƌ Dom Pedro de Alcântara, and one juvenile, RPPN Mata do Professor Baptista (29°23’06”S; 49°50’20”W), 16/IV/2014, col. D.C. Kenne & K.M. Gomes ( UFRGS 5936 ) ; 7: one ♀, Dom Pedro de Alcântara, RPPN Mata do Professor Baptista (29°23’06”S; 49°50’20”W), 16/IV/2014, col. D.C. Kenne & K.M. Gomes ( UFRGS 5950 ) ; 8: one Ƌ, Morro Azul , 12/X/1998, col. L. Buckup & G. Bond-Buckup ( UFRGS 2706 ) ; 9: one Ƌ, Torres , Colônia de São Pedro, 13/X/1985 ( MCP 1067 ) .

Comparative material analyzed. Brazil, Rio Grande do Sul: Parastacus defossus —one Ƌ, Porto Alegre, Lami , Costa do Cerro, 19/VII/2005, col. L.C.E. Daut & J.F. Amato ( UFRGS 4199 ) ; one Ƌ, Porto Alegre, Lami , Costa do Cerro, 19/VII/2005, col. L.C.E. Daut & J.F. Amato ( UFRGS 4200 ) ; one Ƌ, Porto Alegre, Morro do Coco (30°15’40.82” S; 51°2’8.27”W), 15/X/2013, col. K.M. Gomes & C.T. Wood ( UFRGS 5867 ) ; one Ƌ and one ♀, Porto Alegre, Lami , 08/VI/2002, col. L. Buckup & G. Bond-Buckup ( UFRGS 3360 ) ; five ♀, Porto Alegre, Lami (30°11’41’’S; 50°06’00’’W), 2005, col. C. Noro ( UFRGS 4021 ) ; Chile: Parastacus nicoleti —one Ƌ, Mehuim (next to Valdivia), VIII/1997, col. niños del Pueblo ( UFRGS 2405 ) ; Parastacus pugnax —one Ƌ and one ♀, La Florida, Concepción , 19/I/1977 ( UFRGS 2407 ) .

Diagnosis. Rostrum triangular and short. Rostral apex inverted V-shaped, ending in inconspicuous blunt spine. Postorbital carinae obsolete. Cervical groove U-shaped. Areola very narrow and barely discernible. Cheliped propodus globose with large gap between dactylus and fixed finger. Fingers of chelipeds blue. Dorsal margin of dactylus and dorsal and ventral margins of propodus and carpus of second pair of pereiopods with tufts of long simple setae. Mandible caudal molar process unicuspidate with one big cephalodistal cusp. Abdomen shorter and narrower than cephalothorax. Telson subrectangular with small sharp lateral spines. Mid-dorsal carina of exopod of uropods unarmed.

Description. Rostrum: Triangular, wider than long (RL 97.3% of RW), short (11.33% of CL), reaching distal end of second antennular article ( Fig. 6 A, B, C). Dorsum straight, apex inverted V-shaped, ending in inconspicuous straight blunt spine. Dense plumose setae on lateral margins ( Fig. 6 C). Rostral sides convergent and rostral basis divergent. Carinae long, prominent and narrow, extending back to carapace, surpassing rostral basis ( Fig. 6 B, C). Cephalon: Carapace lacking spines or tubercles. CeL 62.7% of CL. Eyes small (CMW 60% of OW), suborbital angle 90° and unarmed ( Fig. 6 C). Front narrow (FW 34.4% of CW). Postorbital carinae longer than rostral carinae (RCL 54.3% of POCL) and weakly prominent (obsolete). Lateral cephalic edge with conspicuous setation ( Fig. 6 C).

Thorax: carapace laterally expanded, deep and wide (CD 54.7% of CL; CW 44.7% of CL; CW 81.7% of CD). Cervical groove U-shaped. Branchiocardiac groove barely visible. Areola narrow and barely discernible, 3.3x as long as wide (26.5% of CL). ( Fig. 6 A).

Abdomen: lacking spines or tubercles, short and narrow (AL 30.7% of CL; AW 68.6% of CW), smooth and with conspicuous setation on pleural margins ( Fig. 6 A, D). Pleural somites with rounded distal margins. S1 pleura with small distal lobe not overlapped by S2 pleura. S2 pleura with deep groove parallel to margin, moderately elongated ( Fig. 6 E, F). AW 48.1% of AL.

Tailfan: telson well calcified in the proximal portion, weakly calcified in the distal margin, subrectangular, longer than wide (TelW 77% of TelL) with small sharp spines on lateral margins; rounded distal margin with abundant long and short simple setae. Dorsal surface with tufts of short setae and a rudimentary dorsomedian longitudinal sulcus ( Fig. 6 G). Uropod protopod bilobed with rounded and unarmed distal margins, proximal lobe largest. Exopod lateral margin unarmed, mid-dorsal carina weakly prominent, ending in small spine. Transverse suture (diaeresis) straight with 6 dorsolateral spines (outer) and 11 dorsolateral spines (inner) on right exopod and with 6 (outer) and 9 (inner) spines on left exopod. Endopod mid-dorsal carina weakly prominent and unarmed, outer lateral margin with small spine at level of exopod transverse sulture ( Fig. 6 G).

Epistome: anterolateral section with conical projection. Posterolateral section with cluster of squamose setiferous tubercles and lateral grooves converging to basis of anteromedian lobe, and reduced median circular concavity. Anteromedian lobe irregularly pentagonal, 1.3x longer than wide, apex rounded and slightly concave, reaching median part of antepenultimate article of antennal peduncle; dorsal surface straight, and basis deeply grooved ( Fig. 7 A).

Thoracic sternites: SLP4 smallest and very close to each other, median keel present and not inflated; SLP5 smaller than SLP6,7,8 and very close to each other, median keel present and not inflated; SLP6 smaller than SLP7,8 and separated from each other, median keel present and inflated; SLP7 largest and separated from each other with dorsal surface slightly concave, median keel present and inflated, bullar lobes absent; SLP8 smaller than SLP7, median keel absent ( Fig. 7 B), vertical arms of paired sternopleural bridges widely separated, bullar lobes very close to each other ( Fig. 7 C).

Antennule: inner ventral border of basal article with blunt spine ( Fig. 7 A).

Antenna: when extended back reaching posterior edge of carapace. Antennal scale widest at distal to midlength and reaching basis of third antennal article, ASW 44.4% of ASL ( Fig. 6 A, D), lateral margin straight, spine strong and distal margin emarginate. Coxa with weakly prominent carina above nephropore, with strong blunt mesial spine. Basis unarmed ( Fig. 6 A).

Mandible: cephalic molar process molariform, caudal molar process unicuspidate with one big cephalodistal cusp and. Incisor lobe with nine teeth. The third tooth from the anterior is the largest ( Fig. 7 E).

Third maxilliped: ischium bearing few setiferous puctuations with few long simple setae on outer margin and on ventrolateral surface and dorsal surface with one row of setiferous punctuations ( Fig. 7 F, G). Merum ventral surface partially covered by long smooth simple setae ( Fig. 7 F). Crista dentata of right and left ischium each bearing 25 teeth. Merus entire ventral surface sparsely covered with simple setae. Exopod longer than ischium, flagellum reaching proximal margin of merus ( Fig. 7 F, G).

First pair of pereiopods (chelipeds): short, subequal and globose (RPrT 26.8% of RPrL; LPrT 26.1% LPrL) ( Fig. 6 A). Ischium ventral surface with 11 tubercles. Merus: right merus (RML) 53.8% of propodus length (RPrL), left merus (LML) 52.7% of propodus length (LPrL); ventral surface with two laterolongitudinal series of tubercles: right merus, inner and outer series bearing 13 tubercles and mesial with several small and medium-sized tubercles, irregularly arranged; left merus, inner series bearing 13 tubercles, external 12, and mesial with same pattern as right merus; dorsal and ventromedial spines absent. Carpus medial dorsal surface straight, not divided by a groove ( Fig. 6 A, 7I). Inner dorsolateral margin with row of tubercles, increasing in size distally. Inner surface bearing some small squamose tubercles. Carpal spine absent ( Fig. 7 I) Propodus width (RPrW and LPrW) 53.1% of length in right cheliped and 48.5% in left cheliped. Dorsal line of palm with two rows of verrucose tubercles, with tufts of short simple and pappose setae on base of tubercles. Ventral surface bearing two rows of squamose tubercles, reaching beginning of fixed finger ( Fig. 7 H). Dactylus: right dactylus (RDL) 66.1% of propodus length (RPrL), left dactylus (LDL) 62.3% of propodus length (LPrL); dorsal surface without tubercles, but with rows of bristle tufts ( Fig. 4 I). Cutting edge of fingers visible. Fixed finger with eight teeth, third and fourth teeth largest. Dactylus with eight teeth, first and third teeth largest. Wide gap between dactylus and fixed finger ( Fig. 7 H).

Second pair of pereiopods: ventral and dorsal margins of dactylus and dorsal and ventral margins of propodus and carpus with tufts of long simple setae ( Fig. 7 J).

Gonopores: presence of both genital apertures on coxae of third and fifth pairs of pereiopods. Female gonopores semi-ellipsoidal (maximum diameter 1.2 mm) with a well-calcified membrane. Male gonopores rounded, opening onto apical end of small, fixed, calcified and truncated phallic papilla, close to inner border of ventral surface of coxae of fifth pair of pereiopods. Male cuticle partition present ( Fig. 7 B).

Branchial count: 20 + epr + r. Branchial arrangement follows the same described by Huxley (1879) and Hobbs (1991) with the epipodite of the first maxiliped with rudimentary podobranchia filaments.

Etymology. A combination of the Latin epithets caeruleus, which alludes to the blue color + dactylus, which alludes to fingers. We recommend the common name “the blue-fingered burrowing crayfish” for this new species.

Measurements. Holotype male, CL 35.4 mm and TL 68 mm. In the type series, CL ranging from 8.18 to 39.95 mm (27.71 ± 10.6 mm). Female paratypes larger than males. FW/CW: 0.37 ± 0.05 (min: 0.31; max: 0.46). RL/RW: 0.83 ± 0.16 (min: 0.49; max: 0.97). CMW/OW: 0.40 ± 0.18 (min: 0.23; max: 0.82). Postorbital carina longer than rostral carina in all specimens analyzed. CW/AW: 1.39 ± 0.26 (min: 0.7; max: 1.72). AuW/RW: 1.05 ± 0.29 (min: 0.68; max: 1.76).

Color of living specimens. Rostrum orange-brown. Cephalothorax anterior and lateral regions orange-brown in adults and brown with shades of greenish brown in juveniles. First pair of pereiopods orange-brown with cerulean-blue to dark-blue fingers. Pereiopods 2–5 light orange to orange. Dorsal pleon orange-brown. Tailfan orange-brown with shades of orange to light orange on dorsal surface of telson ( Fig. 8 D, 9).

Remarks. Female paratypes differ from the holotype in the larger body size and larger pleurae of the abdominal somites. Parastacus caeruleodactylus sp. nov. is morphologically closely related to strong burrowing species of the genus Parastacus , as P. defossus , P. nicoleti and P. pugnax in having chelipeds with a globose propodus and a narrow abdomen in relation to CW. However, it differs from all other Parastacus species in the large gap between the dactylus and the fixed finger of the first pair of pereiopods; the blue coloration of these fingers and in having the dense setation of the dactylus, propodus and carpus of the second pair of pereiopods.

All paratypes presents both masculine and feminine gonopores in the same individual. Male paratypes also present female gonopores semi-ellipsoidal (average maximum diameter 0.97 ± 0.47 mm) covered by a calcified membrane. Female paratypes presents female gonopores ellipsoidal (average maximum diameter 1.04 ± 0.07 mm) covered by a thin and less calcified membrane. Male gonopores are very similar in males and females.

Habitat and ecology. Parastacus caeruleodactylus sp. nov. was collected in flat wetlands near the foothills of the Serra Geral and in the coastal region forests in northeastern Rio Grande do Sul. This physiographic region belongs to the Atlantic Forest Biome and it is characterized by swamp forests ( Fig. 8 A) with permanently or temporarily flooded soils with large amounts of organic matter ( Dorneles & Waechter 2004; Rambo 2005). Burrows of P. caeruleodactylus had chimneys averaging 10 cm in height and width; some individuals were captured in burrows 1 m deep, with only one opening. We found ovigerous females bearing different numbers of eggs, with a maximum of 40 eggs in the initial stage of development attached to the pleopods (see Fig. 9 F). Ecologically, P. caeruleodactylus sp. nov. resembles the strong burrowers species of the genus Parastacus , e.g. P. defossus , P. nicoleti and P. pugnax ; and some other parastacid species in South America, as in the genus Virilastacus and in Australian genera Engaeus Erichson, 1846 , Engaewa Riek, 1967 and Tenuibranchiurus Riek, 1951 , and even in the cambarid genus Fallicambarus Hobbs, 1969 . Ecological features shared by these species include deep burrow system with complex chimneys and particular morphological adaptations to the burrowing lifestyle, as reduced abdomen and reduced eyes; globose cheliped propodus with dactylus moving subvertically or obliquely; branchial chamber extended (narrow areola); and the abundance of setae along the carapace, abdomen and appendages ( Horwitz & Richardson 1986).

Distribution. Parastacus caeruleodactylus sp. nov. appears to have a limited distribution, since it has been found only in swamp forests in northeastern Rio Grande do Sul, in the municipalities of Morrinhos do Sul, Morro Azul, and Dom Pedro de Alcântara. Colônia de São Pedro is an older name for the Dom Pedro de Alcântara municipality ( Fig. 2 ). The main drainages where the species occurs are the Tramandaí and Mampituba hydrographic basins, Coastal Hydrographic Region ( Justus 1990).

Conservation status. The EOO was estimated at 1,152 km ² based on the Otto Bacias shape level 5, indicating that this species can be categorized as Endangered (EOO less than 5,000 km ², according to the IUCN). Subitem "a" for an EOO that is severely fragmented, and subitem "b" (iii) Continuing decline in quality of habitat, are appropriate due to the threats existing in the occurrence areas of P. caeruleodactylus . Rice cultivation may be one cause of habitat loss and fragmentation, because the swamp areas are deforested for cultivation or drained for cattle ranching and construction of human dwellings. The coastal region is largely agricultural, and the use of agrochemicals has been reported ( Cabrera et al. 2008). We therefore suggest that this species be classified as “ENDANGERED B1 ab (iii)”.

Figures

FIGURE 2. Distribution of Parastacus fluviatilis Ribeiro & Buckup sp. nov. and Parastacus caeruleodactylus Ribeiro & Araujo sp. nov in state of Rio Grande do Sul, southern Brazil.

FIGURE 4. Parastacus fluviatilis Ribeiro & Buckup sp. nov., holotype and paratypes: A, epistome (holotype); B, thoracic sternites and gonopores (holotype); C, thoracomere 8, caudal view (holotype); D, antennal scale lateral view (paratype 1); Emandible (paratype 1); F—third maxilliped ventral view (paratype 1); G—third maxilliped dorsal view (paratype 1); H—first pereiopod lateral view (holotype); F, first pereiopod dorsal view (holotype); G, second pereiopod lateral view (holotype). Scale bars: A, C— 2.5 mm; B, J— 5 mm; D, E— 2 mm; F, G— 5 mm; H, I— 1 cm.

FIGURE 6. Parastacus caeruleodactylus Ribeiro & Araujo sp. nov., holotype and paratypes: A, habitus dorsal (holotype); B, cephalon dorsal view (holotype); C, cephalon lateral view (holotype); D, female abdominal somites dorsal view (paratype 1); E, first and second abdominal pleura (holotype); F, first and second abdominal pleura (paratype 1); G, tailfan (holotype). Scale bars: A, D— 1 cm; B, C, E, F, G— 5 mm.

FIGURE 7. Parastacus caeruleodactylus Ribeiro & Araujo sp. nov., holotype and paratypes: A, epistome (holotype); B, thoracic sternites and gonopores (holotype); C, thoracomere 8 caudal view (holotype); D—antennal scale lateral view (paratype 1); E, mandible (paratype 8); F, third maxilliped ventral view (paratype 1); G, third maxilliped dorsal view (paratype 1); H, first pereiopod lateral view (holotype); I, first pereiopod dorsal view (holotype); J, second pereiopod lateral view (holotype). Scale bars: A, C— 2.5 mm; B, J— 5 mm; D, E— 2 mm; F, G— 5 mm; H, I— 1 cm.

FIGURE 8. Parastacus caeruleodactylus Ribeiro & Araujo sp. nov. Habitat and live specimen. A, Swamp forest; B, open chimney in moist soil; C, closed chimney; D, living specimen in moist soil.

FIGURE 9. Parastacus caeruleodactylus Ribeiro & Araujo sp. nov. Living specimens. A, adult male dorsal view; B, adult male lateral view, arrow indicates tufts of long setae coverture in the dorsal and ventral regions of dactylus, propodus and carpus of second pereiopod; C, adult male chelipeds, arrow indicates blue coloration of fingers; D, juvenile dorsal view; E, juvenile lateral view; F, ovigerous female ventral view. Scale bars: A, B, C— 2.5 cm; D, E— 1 cm.