Parastacus pilicarpus, 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 : 10-17

Parastacus pilicarpus sp. nov.

( Figs. 4–8 )

Type material. Holotype: male, Brazil, Santa Catarina, Morro Grande, Bacia do Rio Araranguá (28°41’57.44”S 49°48’8.81”W), 20/VIII/2015, coll. C. Feltrin & F.H. Llanos ( MZUSP 36516 ). Paratypes: 1 – Brazil, Santa Catarina: one female, same data as holotype ( UFRGS 6303 ) ; 2A and 2B – two males, same data as holotype ( UFRGS 6304 ) ; 3 – one female, same data as holotype ( UFRGS 6305 ) ; 4 – one male, same data as holotype ( UFRGS 6306 ) ; 5 – one juvenile, same data as holotype ( UFRGS 6506 ) .

Etymology. Latin: pili = hair; carpus = an article of the cheliped.

Diagnosis. Wide front with a short triangular rostrum. Rostral apex inverted U-shaped and unarmed. Suborbital angle> 90°. Postorbital carinae weakly proeminet. Cervical groove weekly V-shaped. Areola wide, 2.5x as long as wide. Mandible with caudal process bicuspidate with one cephalodistal cusp and one small distoproximal cusp. Incisive lobe with nine teeth. The first tooth from the anterior margin is the largest. S2 pleurae low and short with shallow groove parallel to margin. Epistome with the anteromedian lobe heptagonal, as long as wide. Antennal scale lateral margin curved with a very strong terminal spine. Distal portion of the cheliped carpus with tufs of longs e simple setae. Chelipeds laterally flattened with the cutting edge of the fingers densely covered by setae.

Description of the holotype. Rostrum: triangular, wider than long (RL 64.86% of RW), short (8.87% of CL), reaching the proximal portion of the second article of the antennular peduncle ( Fig. 4A–C) . Dorsum apex inverted “U”-shaped, apex lacking spine ( Fig. 4B, C ). Few plumose setae on lateral margins. Rostral sides convergent and rostral basis parallel. Carinae almost straight, prominent and large, extending back to carapace, surpassing rostral basis ( Fig. 4B, C ).

Cephalon: Carapace lacking spines or tubercles. CeL 65.1% of CL. Eyes large (CMW 81.9% of OW); suborbital angle>90°, unarmed ( Fig. 4A–C) . Front wide (FW 49.2% of CW). Postorbital carinae longer than rostral carinae (RCL 57.5% of POCL) and weakly prominent. Lateral cephalic edge with sparse setation ( Fig. 4A–C) .

Thorax: carapace laterally compressed, deep and narrow (CD 51 % of CL; CW 40% of CL). Cervical groove weekly V-shaped ( Fig. 4A ). Branchiocardiac grooves conspicuous ( Fig. 4A ). Areola wide, 2.5x as long as wide (34.8% of CL) ( Fig. 4A ).

Pleon: lacking spines or tubercles, short and wide (AL 72.3% of CL; AW 92% of CW), smooth, sparsely covered with small setae on pleural margins ( Fig. 4A ). Pleural somites with rounded posterior margins. S1 pleurae with a large distal lobe overlapped by S2 pleurae. S2 pleurae low and short with shallow groove parallel to margin ( Fig. 4D ).

Tailfan: telson weakly calcified in the distal portion, subrectangular, longer than wide (TeW 81.7% of TeL), with inconspicuous sharp spines on lateral margins; rounded distal margin with abundant long plumose setae and short simple setae. Dorsal surface with tufts of short setae and inconspicuous dorsomedian longitudinal groove ( Fig. 4G ). Uropod protopod bilobed, with rounded and unarmed margins; proximal lobe largest; exopod lateral margin bears a small and sharp spine, mid-dorsalcarina few prominent, ending in a sharp spine; transverse suture (diaeresis) straight, with three dorsolateral spines (outer) and two dorsolateral spines (inner) on right exopod and two dorsolateral spines (outer) and three 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. 4G ).

Epistome: anterolateral section with a sharp conical projection. Posterolateral section smooth and with deep lateral grooves converging to the basis of the anteromedian lobe, and large median circular concavity. Anteromedian lobe heptagonal, as long as wide, apex acute and straight, reaching the median part of antepenultimate article of antennal peduncle; dorsal surface straight, and basis with a shallow groove ( Fig. 5A ).

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, separated to each other and with a slightly concave surface, median keel not inflated; SLP7 largest, close to each other and with surface slightly concave, median keel not inflated, bullar lobes absent; SLP8 larger than SLP4, SLP5 and SLP6 and with a slightly concave, median keel absent, vertical arms of paired sternopleural bridges close to each other, bullar lobes close to each other and clearly visible ( Fig. 5B, C ).

Antennule: internal ventral border of basal article with small sharp spine ( Fig. 5A ).

Antenna: when extended back reaching up to the posterior margin of the carapace; antennal scale widest distal at midlength, almost reaching the end of third antennal article, ASW 59% of ASL ( Fig. 5A, D ), lateral margin curved with a very strong terminal spine and distal margin emarginated. Coxa with prominent carina and blunt spine above nephropore. Basis unarmed ( Fig. 5A ).

Mandible: cephalic molar process molariform, caudal molar process bicuspidate with one cephalodistal cusp and one small distoproximal cusp. Incisive lobe with nine teeth. The first tooth from the anterior margin is the largest ( Fig. 5E ).

Third maxilliped: ischium, ventral surface covered by tufts of long and simples setae ( Fig. 5F ), dorsal surface glabrous ( Fig. 5G ), crista dentata bearing 23 and 24 teeth in right and left ischium respectively. Merus ventral surface follows the same pattern that of ischium. Exopod longer than ischium, with flagellum reaching proximal margin of merus ( Fig. 5F, G ).

First pair of pereiopods (chelipeds): laterally flattened and subequal (RPrT 30.1% of RPrL; LPrT 31.8% of LPrL) ( Fig. 5A, H, I ). Ischium ventral surface with 13 tubercles. Merus: right merus (RML) 50.2% of propodus length (RPrL); left merus (LML) 54.2% of propodus length (LPrL); ventral surface with two longitudinal series of tubercles: inner series with 13 tubercles, outer 13 and mesial 12, arranged irregularly on right merus; inner series bearing 13 tubercles, outer 13 and mesial 13, arranged irregularly on left merus; dorsal and midventral spines absent. Carpus with dorsomedial surface divided longitudinally by shallow groove and the distal margin covered with tuffs of long and simple setae ( Fig. 5A, H, I ); internal dorsolateral margin without tubercles; inner surface without tubercles; carpal spine absent ( Fig. 5I ). Propodus width (RPrW and LPrW) 47.7% of length in right cheliped and 49.8% in left cheliped; dorsal surface of palm with squamose tubercles irregularly distributed ( Fig. 5H, I ); inner margin without tubercles; ventral surface bearing two rows of squamose tubercles, reaching the beginning of the fixed finger ( Fig. 5H ). Dactylus: moving subvertically, right dactylus (RDL) 51.9% of propodus length (RPrL), left dactylus (LDL) 58.2% of left propodus (LPrL); dorsal surface without tubercles ( Fig. 5I ). Cutting edge of fingers densely covered by tufts of long and simple setae. Fixed finger and dactylus bearing eight teeth, being the fourth teeth the largest. ( Fig. 5H, I ).

Second pair of pereiopods: ventral and dorsal surface of carpus, propodus and dactylus with sparse covering of simple and long setae ( Fig. 5J ).

Gonopores: Presence of both genital apertures on coxae of third and fifth pairs of pereiopods. Female gonoporessemi-ellipsoidal (maximum diameter 1.69 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. 5B ).

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 21.63 mm and TL 44.78 mm. In type series, CL ranging from 12.90 to 33.54 mm (22.65 ± 7.76 mm). FW/CW: 0.46 ± 0.06 (min: 0.35; max: 0.56). RL/RW: 1.22 ± 0.1 (min: 0.76; max: 1.54). MCW/OW: 0.82 ± 0.1 (min: 0.69; max: 0.96). Postorbital carina longer than rostral carina in all specimens analyzed. CW/PW: 1.10 ± 0.07 (min: 01.08; max: 1.25). AreW/RW: 1.15 ± 0.25 (min: 1.00; max: 1.65) ( Tab. 2 ).

Color of living specimens. Rostrum dark brown. Antennal flagellum light brown. Cephalothorax anterior and lateral regions dark reddish brown to light reddish brown. First pair of pereiopods dark reddish brown dorsally and reddish brown in ventral and lateral surfaces. Dactylus dark reddish brown in the proximal portion and reddish brown distally. Pereiopod pairs 2–5 light reddish brown to reddish brown. Dorsal pleon and tailfan reddish brown ( Fig. 6C ).

Remarks. Parastacus pilicarpus sp. nov . is morphologically similar to P. buckupi sp. nov . in having the rostral apex inverted U-shaped and short rostral carinae. Parastacus pilicarpus sp. nov . is also similar to P. buckupi sp. nov ., P. fluviatilis and P. pilimanus by the presence of tufts of long and simple setae on the cutting edge of fingers of chelipeds ( Fig. 7 ). Parastacus pilicarpus sp. nov . differs from all other Parastacus spp. in having the epistome anteromedian lobe heptagonal, as long as wide ( Fig 5A ), antennal scale lateral margin curved with a very strong terminal spine ( Fig. 5D ), mandible incisive lobe with the first tooth from the anterior margin being the largest and the presence of tufts of long and simple setae in the distal portion of carpus ( Fig. 5I ). All specimens are intersexed. In males paratypes the female gonopores are semi-ellipsoidal (average maximum diameter 1.69 mm) covered by a calcified membrane ( Fig. 5B ). The male gonopores are similar in all type material.

Habitat and Ecology. All animals were collected in the headwaters of Manoel Alves stream which is considered a first order stream. Based on photographs ( Fig. 6A, B ), it is possible to infer that the margins are surrounded by riparian vegetation, gravel and rocks probably from basaltic origin. Despite the absence of information on burrowing behavior and burrow morphology, the possibility of the species shows some burrowing ability, cannot be discarded since according to Buckup and Rossi (1980) burrowing behavior is probably found in all species of Parastacus .

Distribution. Parastacus pilicarpus sp. nov . is so far recorded in the headwater of Manoel Alves stream in the municipality of Morro Grande, state of Santa Catarina, southern Brazil ( Fig. 8 ).

Conservation status. The EOO was estimated at approximately 1,037.123 km ² ( Fig. 8 ), indicating that this species should be included in the Endangered – EN category, in which the EOO is less than 5,000 km ² ( IUCN, 2012). This classification as EN takes into consideration the subitem “a”: for an EOO, which is severely fragmented; and subitem “b” (iii): continuing decline in quality of habitat. The region of Araranguá River basin is target of industrial and agricultural waste (Araújo et. al., 1989). The Araranguá River basin is recognized as an endemic area of fish species ( Malabarba and Isaia, 1992; Reis and Schaefer, 1998), as Hollandichthys taramandahy Bertaco & Malabarba, 2013 (Lambari- striped). Unfortunately, the area shows high level of anthropogenic disturbances, as the deforestation of riparian forest ( Bertaco and Malabarba, 2013). However, we do not have enough surveys to make that claim yet for the state of Santa Catarina. Consequently, the EOO for P. pilicarpus sp. nov. could be underestimated in our study. Taking this into account, we decided to classify this species as DATA DEFICIENT.

Figures

Figure 4. Parastacus pilicarpus sp. nov. A, habitus dorsal view (holotype); B, cephalon dorsal view (holotype); C, cephalon lateral view (holotype); D, female pleon, dorsal view (paratype 1); E, male first to third pleonal pleura (holotype); F, female first to third pleonal pleura (paratype 1); G, telson and uropods dorsal view (holotype). Scale bars: A, D, F – 1 cm; E - 5 mm; C, G – 3.33 mm; B – 2.5 mm.

Figure 5. Parastacus pilicarpus sp. nov. 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 1); F, third maxilliped ventral view (paratype 1); G, third maxilliped dorsal view (paratype 1); H, first pereiopod lateral view (holotype); I, first pereipod dorsal view (holotype); J,second pereiopod lateral view (holotype).Scale bars:A, E– 2.50 mm; B,C, H, J – 5 mm; D –2.00 mm; F,G,I –3.33 mm.

Figure 6. Parastacus pilicarpus sp. nov., habitat and living specimens. A, B, Typical habitat, a first order stream in the municipality of Morro Grande, state of Santa Catarina; C, living specimen. Photographs by Caio R. M. Feltrin.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 2. Measurements (mm) of the type series of Parastacus pilicarpus sp. nov. (* broken appendage). For abbreviations see Material and Methods section.

	Holotype (MZUSP 36516)	Paratype 1 (UFRGS 6303)	Paratype 2A (UFRGS 6304)	Paratype 2B (UFRGS 6304)	Paratype 3 (UFRGS 6305)	Paratype 4 (UFRGS 6306)	Paratype 5 (UFRGS 6506)
Sex	M	F	M	M	F	M	Juv
TL	44.78	64.62	38.57	43.53	65.17	32.61	25.62
CL	21.63	33.54	18.87	21.87	32.70	17.10	12.90
CW	8.66	13.97	7.40	9.17	12.95	6.18	4.80
CD	11.04	17.05	9.55	10.98	16.37	8.53	6.38
CSL	14.08	22.37	12.36	14.17	22.16	11.03	8.76
RL	1.92	3.35	1.87	2.19	3.65	1.69	1.99
RW	2.96	4.34	2.22	2.37	3.80	2.06	1.52
CMW	1.13	1.60	0.96	1.25	1.62	0.96	0.77
OW	1.38	2.16	1.39	1.34	1.96	1.00	1.02
FW	4.26	4.93	3.64	4.20	6.01	3.37	2.71
RCL	2.80	4.20	2.80	3.49	4.17	2.84	2.17
POCL	4.87	5.68	4.14	3.39	8.09	4.58	4.45
ASL	2.61	4.12	2.37	2.86	4.81	2.09	2.06
ASW	1.54	1.90	1.12	1.26	1.92	1.09	0.81
AuL	7.54	9.00	6.21	7.72	10.81	6.37	3.91
AuW	3.01	4.96	2.23	3.93	4.15	2.06	1.62
PW	7.97	11.15	17.91	8.19	12.14	5.92	4.45
PL	15.63	25.24	13.79	16.18	31.62	12.29	9.59
RPrT	5.40	*	3.76	3.78	*	3.44	1.35
RPrL	17.95	*	12.73	14.32	*	12.53	6.73
RPrW	8.57	*	6.21	6.59	*	5.73	2.51
RML	9.02	*	7.96	8.34	*	7.34	470
RDL	9.32	*	7.51	8.50	*	6.78	3.92
LPrT	5.35	9.43	3.69	5.99	*	3.58	1.87
LPrL	16.81	33.12	13.02	17.03	*	12.93	7.63
LPrW	8.38	13.89	6.24	8.76	*	6.31	3.12
LML	9.11	16.60	8.13	9.32	*	7.20	5.24
LDL	9.79	18.62	7.26	8.37	*	7.12	4.75
TeL	6.40	9.21	5.56	6.29	9.75	4.68	3.86
TeW	5.23	8.04	4.64	5.52	8.02	4.08	3.00
Gon	1.22	1.69	0.92	1.3	1.64	0.78	0.47