Parastacus buckupi, Huber & Ribeiro & Araujo, 2018

Huber, Augusto Frederico, Ribeiro, Felipe Bezerra & Araujo, Paula Beatriz, 2018, New endemic species of freshwater crayfish Parastacus Huxley, 1879 (Crustacea: Decapoda: Parastacidae) from the Atlantic forest in southern Brazil, Nauplius 26, pp. 1-18 : 3-8

Parastacus buckupi sp. nov.

( Figs. 1–3 , 8 )

Parastacus brasiliensis .— Vilella et al., 2004: 22.

Type material. Holotype: male, Brazil, Rio Grande do Sul, Maquiné, Arroio Carvão (UTM 574562/6731725), 23/V/2001, coll. F.S. Vilella ( MZUSP 36515 ) . Paratypes: 1 - Brazil, Rio Grande do Sul: one male, Maquiné, Arroio Carvão , 25/X/2001, coll. F.S. Vilella ( UFRGS 3581 ) ; 2 - one male, Maquiné, Arroio Carvão , 17/VIII/2001, coll. F.S. Vilella ( UFRGS 3893 ) ; 3 - one female, Maquiné, Arroio Carvão , 17/VIII/2001, coll. F.S. Vilella ( UFRGS 3894 ) ; 4 - one female, Maquiné, Arroio Carvão , 25/X/2001, coll. F.S. Vilella ( UFRGS 3895 ) ; 5 - one male, Maquiné, Arroio Carvão , 25/X/2001, coll. F.S. Vilella ( UFRGS 3896 ) .

Etymology. Named in honor of the Emeritus Professor Ludwig Buckup from Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.He was one of the pioneers of carcinological studies in Brazil, dedicating several years of his life to the study of decapod crustaceans, especially conducting research on the biology and taxonomy of freshwater crayfish.

Diagnosis. Narrow cephalon front with a short triangular rostrum.Rostral apex inverted U-shapedwith an upward blunt spine. Suborbital angle 90°. Postorbital carinae weakly prominent. Cervical groove weakly V-shaped. Areola narrow, 2.1x as long as wide. Telson with acute distal margin. Mandible with caudal molar process unicuspidate with one cephalodistal cusp, incisive lobe with ten teeth. S2 pleurae low and long with shallow groove parallel to margin. Chelipeds large and globose with the cutting edge of fingers covered by tufts of long and simple setae more abundant in the proximal portion.

Description of the holotype. Rostrum: triangular, longer than wide (RW 89% of RL), short (10% of CL), reaching proximal portion of the second article of the antennular peduncle ( Fig. 1A–C) . Dorsum straight, apex inverted U-shaped, ending in an upward blunt spine ( Fig. 1B, C ). Few plumose setae on lateral margins. Rostral carinae almost straight, prominent and narrow, extending back to carapace, surpassing rostral basis ( Fig. 1B, C ); sides convergent and basis slightly divergent ( Fig. 1B ).

Cephalon: Carapace lacking spines or tubercles. CeL 63.41% of CL. Eyes small (CMW65%of OW); suborbital angle 90° and unarmed ( Fig.1C ). Front narrow (FW 36% of CW). Postorbital carinae longer than rostral carinae (RCL 71% of POCL) and weakly prominent. Lateral cephalic edge with sparse setation ( Fig. 1A–C) .

Thorax: carapace laterally compressed, deep and wide (CD 42% of CL; CW 45% of CL). Cervical groove weakly V-shaped. Branchiocardiac grooves inconspicuous ( Fig. 1A ). Areola narrow, 2.1x as long as wide (31% of CL) ( Fig. 1A ).

Pleon: lacking spines or tubercles, short and wide (PL 65% of CL; PW 83.4% of CW), smooth, sparsely covered with small setae on pleural margins ( Fig. 1A ). Pleural somites with rounded posterior margins. S1 pleurae with a large distal lobe not overlapped by S2 pleurae. S2 pleurae low and long with shallow groove parallel to margin ( Fig. 1D–F) .

Tailfan: telson weakly calcified in the distal margin, subrectangular, longer than wide (TeW 90% of TeL), with small sharp spines on lateral margins; acute distal margin with abundant long plumose setae and short simple setae; dorsal surface with tufts of short setae and inconspicuous dorsomedian longitudinal groove ( Fig. 1G ). Uropod protopod bilobed, with rounded and unarmed margins; proximal lobe largest ( Fig. 1G ); exopod lateral margin bears a small and sharp spine, mid-dorsal carina few prominent, ending in a sharp spine; transverse suture (diaeresis) straight, with four dorsolateral spines (outer) and four dorsolateral spines (inner) on right exopod and six dorsolateral spines (outer) and five dorsolateral spine (inner) on the left exopod; endopod, mid-dorsal carina few prominent, ending in a very sharp spine; lateral margin with one sharp spine at level of diaeresis ( Fig. 1G ).

Epistome: anterolateral section with a blunt conical projection. Posterolateral section smooth and with deep lateral grooves converging to the basis of the anteromedian lobe, and small median circular concavity. Anteromedian lobe pentagonal, as long as wide, apex acute and straight with serrate setae, reaching median part of antepenultimate article of antennal peduncle; dorsal surface straight, and basis with a shallow groove ( Fig. 2A ).

Thoracic sternites: SLP4 smallest and close to each other, median keel present and not inflated; SLP5 small and close to each other, median keel present and not inflated; SLP6 larger than SLP4 and SLP5 and with a slightly concave surface, median keel inflated; SLP7 largest and with surface slightly concave, median keel inflated, bullar lobes absent; SLP8 small and slightly concave, median keel absent, vertical arms of paired sternopleural bridges close to each other, bullar lobes separated and clearly visible ( Fig. 2B, C ).

Antennule: internal ventral border of basal article with one small sharp spine ( Fig. 2A ).

Antenna: when extended back reaching up to the posterior margin of the carapace. Antennal scale widest distally at midlength, reaching midlength of third antennal article, ASW 42.7% of ASL ( Fig. 2A, D ), lateral margin curved with strong spine and distal margin straight. Coxa with prominent carina above nephropore and a blunt spine laterally displaced. Basis unarmed ( Fig. 2A ).

Mandible:cephalic molar process molariform, caudal molar process unicuspidate with one cephalodistal cusp. Incisive lobe with ten teeth. The fourth tooth from the anterior margin is the largest ( Fig. 2E ).

Third maxilliped: ischium, ventral surface partially covered by tufts of long and simple setae ( Fig. 2F ); dorsal surface glabrous ( Fig.2G ). Crista dentata bearing 27 and 30 teeth in right and left ischium respectively. Merus ventral surface partially covered by tufts of long and simples setae. Exopod longer than ischium, with flagellum reaching proximal margin of merus ( Fig. 2F, G ).

First pair of pereiopods (chelipeds): large and subequal, globose (RPrT 29.4% of RPrL; LPrT 29.3% of LPrL) ( Figs. 1A ; 2H, I ). Ischium ventral surface with 17 tubercles. Merus: right merus (RML) 50.5% of propodus length (RPrL); left merus (LML) 53.2% of propodus length (LPrL); ventral surface with two longitudinal series of tubercles: inner series with 16 tubercles, outer 17 and mesial 26, arranged irregularly on right merus; inner series bearing 13 tubercles, outer 16 and mesial 21, arranged irregularly on left merus; dorsal and midventral spine absent. Carpus with dorsomedial surface divided longitudinally by shallow groove ( Fig. 1A ; 2I ). Internal dorsolateral margin with row of tubercles, distally increasing in size; inner surface with up to nine small mesial tubercles; carpal spine absent ( Fig. 2I ). Propodus width (RPrW and LPrW) 49.3% of length in right cheliped and 49.5% in left cheliped; dorsal surface of palm with squamose tubercles irregularly distributed ( Fig. 2H, I ); inner margin without tubercles; ventral surface bearing two rows of squamose tubercles, reaching the beginning of the fixed finger ( Fig. 2H ). Dactylus: moving subvertically, right dactylus (RDL) 57.6% of propodus length (RPrL), left dactylus (LDL) 57.5% of left propodus (LPrL); dorsal surface without tubercles ( Fig. 2I ). Cutting edge of fingers covered by tufts of long and simple setae more abundant in the proximal portion ( Fig. 2H ). Fixed finger and dactylus both bearing seven teeth, the third teeth is the largest. ( Fig. 2H, I ).

Second pair of pereiopods: ventral and dorsal surface of carpus, propodus and dactylus with sparse covering of simple long setae ( Fig. 2J ).

Gonopores: Presence of both genital apertures on coxae of third and fifth pairs of pereiopods. Female gonoporessemi-ellipsoidal (maximum diameter 1.46 mm) with awell-calcifiedmembrane. Male gonopores rounded, opening onto apical end of a 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. 2B ).

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

Measurements. Holotype male, CL 39.11 mm and TL 74.76 mm. In type series, CL ranging from 12.28 to 39.11 mm (22.42 ± 9.44 mm). FW/CW: 0.37 ± 0.02 (min: 0.35; max: 0.41). RL/RW: 1.2 ± 0.1 (min: 1.08; max: 1.33). MCW/OW: 0.72 ± 0.1 (min: 0.55; max: 0.82). Postorbital carina longer than rostral carina in all specimens. CW/PW: 1.17 ± 0.04 (min: 1.12; max: 1.25). AreW/RW: 1.08 ± 0.26 (min: 0.73; max: 1.46) ( Tab. 1 ).

Color of living specimens. Rostrum dark brown. Antennal flagellum light brown. Cephalothorax anterior and lateral regions dark brown to reddish brown. Chelipeds brown with dark brown fingers. Pereiopod pairs 2–5 light brown to dark brown. Dorsal pleon and tailfan light brown to reddish brown ( Fig. 3C ).

Remarks. Parastacus buckupi sp. nov . is morphologically similar to P. brasiliensis in having a wide pleon, large chelipeds, rostral apex inverted U-shapedwith an upward blunt spine and a pentagonal anteromedian lobe of epistome. Parastacus buckupi sp. nov. is also similar to P. fluviatilis and P. pilimanus in having the cutting edge of fingers covered by tufts of long and simple setae ( Fig. 7 ). Parastacus buckupi sp. nov. differs from all other Parastacus species by the large and globose chelipeds with tufts of plumose setae in the cutting edge of fingers, which are more abundant in the proximal portion ( Fig. 7A ) and telson subrectangular with acute distal margin ( Fig. 1A, G ). It was observed that the distal margin of the telson is rounded in smaller specimens (Paratype 1–5; Tab. 1 ). All specimens are intersexed. In males paratypes, the female gonopores are semi-ellipsoidal (average maximum diameter 1.76 mm) covered by a calcified membrane. The male gonopores are similar in all type material.

Habitat and Ecology. Carvão stream is included in the Serra Geral Biological Reserve ( Vilella et al., 2004), with headwaters located about 800 m above sea level (a.s.l.; Fig. 3A, B ). This stream is nearly 3.5 km of length with a catchment area of approximately 6 km ² and the margins are surrounded by riparian vegetation including Araucaria angustifolia (Bertol.) Kuntze, 1898 and grasslands (Araucaria Forest province) ( IBGE, 1990; Vilella et al., 2004; Sydow et al., 2008; Morrone, 2014). The substrate of the creek is basaltic with arenite in the lower portions ( Vilella et al., 2004) ( Fig. 3A, B ). Data concerning burrow morphology and burrowing behavior are not available since they were not recorded when the specimens were collected. However, it is possible that the new species shows some level of burrowing activity especially considering that the burrowing behavior is probably found in all species of Parastacus ( Buckup and Rossi, 1980) .

Distribution. Parastacus buckupi sp. nov . is so far recorded in Carvão stream in the municipality of Maquiné, state of Rio Grande do Sul, southern Brazil ( Fig. 8 ).

Conservation status. The EOO was estimated at approximately 301.885 km ² ( Fig. 8 ), indicating that this species can be included in the Endangered – EN category, in which the EOO is less than 5,000 km ² ( IUCN, 2012). The species is categorized as EN under the subitem “a”: for an EOO, which is severely fragmented; and subitem “b” (iii): continuing decline in quality of habitat. Both subitems are compatible with the threats existing in the species occurrence area: a small fragment of a stream with approximately 6 km ² of catchment area (Vilella et. al., 2004). The region of Maquiné basin is impacted mainly through the substitution of natural vegetation by agriculture ( Becker et al., 2004). Conservation in the Maquiné basin is of fundamental importance since the region constitutes the southern limit of dense Ombrophylous Forest (Atlantic Forest) and all associated animals and plants ( Bencke and Kindel, 1999; Becker et al., 2004). We suggest therefore that the conservation status of this species be classified as ENDANGERED B1ab(iii).

Figures

Figure 1. Parastacus buckupi sp. nov. A, habitus dorsal view (holotype); B, cephalon dorsal view (holotype); C, cephalon lateral view (holotype); D, femalepleon (paratype 4); E,male first to third pleonal pleura (holotype); F, female first to thirdpleonal pleura (paratype 4); G, tailfan dorsal view (holotype). Scale bars: A – 1 cm; B–D, G – 5 mm; E, F – 3.33mm.

Figure 2. Parastacus buckupisp.nov.A, epistome (holotype); B,thoracic sternitesand gonopores (holotype); C, thoracomere 8,caudal view (holotype); D, antennal scale lateral view (paratype 4); E,mandible (paratype 4); F, thirdmaxilliped ventral view (paratype 4); G, third maxilliped dorsal view (paratype 4); H, first pereiopod lateral view (holotype); I, first pereipod dorsal view (holotype); J, second pereiopod lateral view (holotype). Scale bars: A – 3.3 mm; B, H–J – 5 mm; C, D – 1.6 mm; F, G – 2.50 mm; E – 2.00 mm.

Figure 3. Parastacus buckupi sp. nov, habitat and living specimens. A, B, Typical habitat, a first order stream at Maquiné, state of Rio Grande do Sul; C, living specimen, habitus, dorsal view. Photographs by Fábio S. Vilella. No available information of scale in photograph C.

Figure 7. Comparative board of the chelipeds of selected species of genus Parastacus Huxley, 1879 with pilous cutting edge of fingers. A – P. buckupi sp. nov. (holotype); B – P. pilicarpus sp. nov. (holotype); C – P. fluviatilis Ribeiro & Buckup in Ribeiro et al. (2016) (UFRGS 2704); D – P. pilimanus (von Martens, 1869) (UFRGS 2413, CL 38.74). Scale bars: 1 cm.

Figure 8. Distribution of Parastacus buckupi sp. nov. (star) and P. pilicarpus sp. nov. (triangle) in the states of Rio Grande do Sul and Santa Catarina, southern Brazil.

Tables

Table 1. Measurements (mm) of the type series of Parastacus buckupi sp.nov.For abbreviations see Materialand Methods section

	Holotype (MZUSP 36515)	Paratype 1 (UFRGS 3581)	Paratype 2 (UFRGS 3893)	Paratype 3 (UFRGS 3894)	Paratype 4 (UFRGS #3895)	Paratype 5 (UFRGS 3896)
Sex	M	M	M	F	F	M
TL	74.76	49.03	30.77	31.05	47.24	46.42
CL	39.11	23.76	14.5	12.28	22.62	22.27
CW	17.59	9.6	6.28	6.5	8.96	9.59
CD	16.38	13.48	7.39	8.41	12.23	12.42
CSL	24.8	16.35	10.29	10.58	15.29	14.36
RL	4.39	3.3	2.23	2.48	2.53	2.86
RW	3.91	2.48	1.84	1.87	2.34	2.43
CMW	1.41	1.24	0.79	0.9	1.23	1.11
OW	2.17	1.62	1.43	1.12	1.5	1.49
FW	6.34	3.66	2.35	2.69	3.49	3.45
RCL	6.08	4.16	2.65	2.31	3.65	3.65
POCL	8.58	5.18	3.67	3.25	4.86	4.68
ASL	4.42	3.26	1.8	1.81	2.68	2.43
ASW	1.89	1.54	1.03	0.99	1.41	1.39
AuL	12.06	6.03	3.66	4.07	5.93	6.11
AuW	5.73	2.31	1.36	2.16	2.2	3.12
PW	14.68	8.43	4.99	5.76	7.69	8.23
PL	25.4	20.4	13.45	11.54	17.88	16.22
RPrT	9.39	4.47	3.12	1.46	5.06	3.74
RPrL	31.92	18.18	10.01	5.8	16.94	13.65
RPrW	15.75	7.99	4.78	1.78	8.7	6.78
RML	16.12	10.05	5.32	4.52	9.52	8.95
RDL	18.38	10.37	5.68	3.45	9.64	7.98
LPrT	9.34	6.08	2.93	3.43	4.69	5.87
LPrL	31.89	21.19	10.28	11.52	16.11	18.44
LPrW	15.77	9.59	4.71	5.39	8.22	8.88
LML	16.96	11.17	5.74	6.89	9.83	9.67
LDL	18.34	11.71	6.04	6.09	8.66	9.86
TeL	10.8	6.98	3.98	4.61	6.46	6.47
TeW	9.73	6	3.76	3.57	5.56	5.46
Gon	1.76	1.13	0.37	0.58	1.08	1.11

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