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

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Parastacus caeruleodactylus Ribeiro & Araujo

sp. nov.

Parastacus caeruleodactylus Ribeiro & Araujo  sp. nov.

( Figs. 2View FIGURE 2, 6–9View FIGURE 6View FIGURE 7View FIGURE 8View FIGURE 9)


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 34287View Materials)GoogleMaps 

Paratypes. 1: Brazil, Rio Grande do Sul—one ♀, same data as holotype ( UFRGS 5931View Materials)GoogleMaps  ; 2: one ♀, same data as holotype ( UFRGS 5932View Materials)GoogleMaps  ; 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 5934View Materials)GoogleMaps  ; 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 5935View Materials)GoogleMaps  ; 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 5936View Materials)GoogleMaps  ; 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 5950View Materials)GoogleMaps  ; 8: one Ƌ, Morro Azul , 12/X/1998, col. L. Buckup & G. Bond-Buckup ( UFRGS 2706View Materials)  ; 9: one Ƌ, Torres , Colônia de São Pedro, 13/X/1985 ( MCP 1067View Materials)  .

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 4199View Materials)  ; one Ƌ, Porto Alegre, Lami , Costa do Cerro, 19/VII/2005, col. L.C.E. Daut & J.F. Amato ( UFRGS 4200View Materials)  ; 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 5867View Materials)GoogleMaps  ; one Ƌ and one ♀, Porto Alegre, Lami , 08/VI/2002, col. L. Buckup & G. Bond-Buckup ( UFRGS 3360View Materials)  ; five ♀, Porto Alegre, Lami (30°11’41’’S; 50°06’00’’W), 2005, col. C. Noro ( UFRGS 4021View Materials)GoogleMaps  ; Chile: Parastacus nicoleti  —one Ƌ, Mehuim (next to Valdivia), VIII/1997, col. niños del Pueblo ( UFRGS 2405View Materials)  ; Parastacus pugnax  —one Ƌ and one ♀, La Florida, Concepción , 19/I/1977 ( UFRGS 2407View Materials)  .

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. 6View FIGURE 6 A, B, C). Dorsum straight, apex inverted V-shaped, ending in inconspicuous straight blunt spine. Dense plumose setae on lateral margins ( Fig. 6View FIGURE 6 C). Rostral sides convergent and rostral basis divergent. Carinae long, prominent and narrow, extending back to carapace, surpassing rostral basis ( Fig. 6View FIGURE 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. 6View FIGURE 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. 6View FIGURE 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. 6View FIGURE 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. 6View FIGURE 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. 6View FIGURE 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. 6View FIGURE 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. 6View FIGURE 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. 7View FIGURE 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. 7View FIGURE 7 B), vertical arms of paired sternopleural bridges widely separated, bullar lobes very close to each other ( Fig. 7View FIGURE 7 C).

Antennule: inner ventral border of basal article with blunt spine ( Fig. 7View FIGURE 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. 6View FIGURE 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. 6View FIGURE 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. 7View FIGURE 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. 7View FIGURE 7 F, G). Merum ventral surface partially covered by long smooth simple setae ( Fig. 7View FIGURE 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. 7View FIGURE 7 F, G).

First pair of pereiopods (chelipeds): short, subequal and globose (RPrT 26.8% of RPrL; LPrT 26.1% LPrL) ( Fig. 6View FIGURE 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. 6View FIGURE 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. 7View FIGURE 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. 7View FIGURE 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. 4View FIGURE 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. 7View FIGURE 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. 7View FIGURE 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. 7View FIGURE 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. 8View FIGURE 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. 8View FIGURE 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. 9View FIGURE 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. 2View FIGURE 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)”.


Museu de Zoologia da Universidade de Sao Paulo


Universidade Federale do Rio Grande do Sul


Pontificia Universidade Catolica do Rio Grande do Sul


Tree Pathology Cooperative Program


Culture Collection of Algae at the University of Vienna


Ludlow Museum