Parastacus manezinho, Ribeiro & Araujo, 2024

Ribeiro, Felipe Bezerra & Araujo, Paula Beatriz, 2024, Taxonomic review of the genus Parastacus Huxley, 1879 (Decapoda: Astacidea: Parastacidae) with description of five new species, Zootaxa 5455 (1), pp. 1-84 : 63-68

Parastacus manezinho sp. nov.

( Figs. 39–42 , Table 3)

Holotype. male, Brazil, Santa Catarina, Florianópolis, Fazenda Experimental da Ressacada —­ UFSC (- 28.683086 S; - 48.54006 W), 23/IX/2013, coll. F. B. Ribeiro, M. P. Almerão & P. B. Araujo ( MZUSP 43369 ).

Paratypes. Brazil, Santa Catarina —­ 1: one female, same data as holotype ( UFRGS 6489 ) ; 2: one female, same data as holotype ( UFRGS 6490 ) ; 3: one female, same data as holotype ( UFRGS 6491 ) ; 4: one male, same data as holotype ( UFRGS 6493 ) ; 5: one male, same data as holotype ( UFRGS 7074 ) ; 6: one male, same data as holotype ( UFRGS 7075 ) .

Etymology. Named based on the regional expression “manezinho ”, typical of the state of Santa Catarina, which is is the gentile popularly used to designate the natives of Florianópolis; used as a noun in apposition. We also suggest the common name “manezinho crayfish” for this species.

Diagnosis. Rostrum triangular and with apex U-shaped, ending in a downward spine. Carpal spine present in chelipeds. Dorsal surface of chelipeds palm with three rows of verrucous tubercles.

Description.

Rostrum: triangular, longer than wide (RL 82.9% of RW), short (11.1% of CL), reaching half of the second article of the antennular peduncle ( Fig. 39A–C ). Dorsum deflexed, apex inverted “U”-shaped, ending in a downward spine ( Fig. 39B, C ). Few plumose setae on lateral margins. Rostral carinae straight prominent and narrow, extending back to carapace, slightly surpassing rostral basis, rostral carinae sides convergent and rostral carinae basis divergent ( Fig. 39B, C ).

Cephalon: Carapace lacking spines or tubercles. CeL 63.2% of CL. Eyes large (CMW 71.27% of OW); suborbital angle> 90°, unarmed ( Fig. 39C ). Front narrow (FW 44.5% of CW). Postorbital carinae longer than rostral carinae (RCL 70.6% of POCL) and prominent. Lateral cephalic edge with sparse setation ( Fig. 39A–C ).

Thorax: carapace laterally compressed, deep and narrow (CD 54.8% of CL; CW 43.3% of CL). Cervical groove strongly V-shaped. Branchiocardiac grooves conspicuous ( Fig. 39A ). Areola narrow, 2.6 as long as wide (30.21% of CL) ( Fig. 39A ).

Pleon: lacking spines or tubercles, long and wide (PL 81.7% of CL; PW 94.9% of CW), smooth, covered with small setae on pleural margins ( Fig. 37A ). Pleural somites with rounded posterior margins. S2 pleurae low and short with deep groove parallel to margin ( Fig. 39D, E, F ).

Tailfan: telson uniformly calcified, subtriangular, longer than wide (TeW 84.3% of TeL), with small 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. 39E ). Uropod protopod bilobed, with rounded and unarmed margins; proximal lobe largest. Exopod lateral margin bears a small and sharp spine, mid-dorsal carina few prominent, ending in a sharp spine. Transverse suture (diaeresis) straight, with eleven dorsolateral spines (outer) and nine dorsolateral spines (inner) on right exopod and ten dorsolateral spines (outer) and seven dorsolateral spine (inner) on the left exopod. Endopod, mid-dorsal carina few prominent, ending in a small spine; lateral margin with one sharp spine at the level of exopod transverse suture ( Fig. 39E ).

Epistome: anterolateral section with blunt conical projection. Posterolateral section smooth and with deep lateral grooves converging to the basis of the anteromedian lobe, and with a small median concavity. Anteromedian lobe pentagonal, 1.2x longer than wide, apex rounded with surpassing median part of antepenultimate article of antennal peduncle; dorsal surface concave at the apex with serrated setae, and basis with a shallow groove ( Fig. 40A ).

Thoracic sternites: SLP4 very close to each other, median keel present and not inflated; SLP5 smallest, median keel present and not inflated; SLP6 larger than SLP4 and SLP5 with a slightly concave surface, median keel inflated; SLP7 largest and with surface slightly concave, median keel inflated, bullar lobes absent; SLP8 straight, median keel absent, vertical arms of paired sternopleural bridges close to each other, bullar lobes separated to each other and clearly visible ( Fig. 40B, C ).

Antennule: internal ventral border of basal article without spine ( Fig. 40A ).

Antenna:when extended back reaching S2.Antennal scale widest at midlength, reaching the end of third antennal article, ASW 45.9% of ASL ( Fig. 38A, D ), lateral margin straight, spine strong and distal margin emarginate. Coxa with prominent carina and one blunt spine above nephropore. Basis unarmed ( Fig. 40A ).

Mandible: cephalic molar process molariform, caudal molar process unicuspidate with one cephalodistal cusp. Incisor lobe with nine teeth. The third tooth from the anterior margin is the largest ( Fig. 40E ).

Third maxilliped: ischium, ventral surface with tufts of setae ( Fig. 38F ); dorsal surface with few sparse small and simple setae ( Fig. 40G ). Crista dentata bearing 22 and 23 teeth in right and left ischium respectively. Merus ventral surface with longitudinal rows of long and simple setae. ( Fig. 30F, G ).

First pair of pereiopods (chelipeds): large and subequal, laterally flatenned (RPrT 22.1% of RPrL; LPrT 22.41% of LPrL) ( Fig. 39A ). Ischium ventral surface with 13 tubercles. Merus: right merus (RML) 53.7% of propodus length (RPrL); left merus (LML) 54.8% of propodus length (LPrL); ventral surface with two longitudinal series of tubercles: inner series with 12 tubercles, outer 12 and mesial 11, arranged irregularly on right merus; inner series bearing 14 tubercles, outer 13 and mesial 12, arranged irregularly on left merus. Dorsal and midventral spines present. Carpus divided by a shallow transversal groove ( Fig. 39A ; Fig. 40I ). Internal dorsolateral margin with row of tubercles, increasing in size distally; inner surface with few small mesial tubercles. Carpal spine present ( Fig. 40I ). Propodus width (RPrW and LPrW) 45.6% of length in right cheliped and 46% in left cheliped. Dorsal surface of palm with three rows of verrucous tubercles ( Fig. 40H, I ). Inner margin without tubercles. Ventral surface bearing two rows of squamose tubercles, reaching the beginning of the fixed finger ( Fig. 40H ), right dactylus (RDL) 58.7% of propodus length (RPrL), left dactylus (LDL) 60.2% of left propodus (LPrL); dorsal surface with rows of setiferous punctuations ( Fig. 40I ). Cutting edge of fingers visible. Fixed finger with nine teeth, third teeth largest. Dactylus with nine teeth, third tooth largest ( Fig. 40H, I ).

Fig. 41. Parastacus manezinho sp. nov., habitat and living specimen: A—­ habitat, wetland in the municipality of Florianópolis, state of Santa Catarina, Brazil; B—­ chimney; C—­ living specimen. tw = temnocephalan worm.

Second pair of pereiopods: ventral and dorsal surface of carpus, propodus and dorsal surface of dactylus with sparse covering of simple long setae ( Fig. 40J ).

Gonopores: Presence of both genital apertures on coxae of third and fifth pairs of pereiopods. Female gonopores semi-ellipsoidal (maximum diameter 1.12 mm) with well-calcified membrane. 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. 40B ).

Remarks. Parastacus manezinho sp. nov. resembles P. tuerkayi in having large chelipeds with the dorsal surface of palm with three rows of verrucous tubercles, but it can be distinguished from that species by the shape of the epistome anteromedian lobe and the number of teeth in the cephalic molar process of the mandible.

Color of living specimens. Rostrum, cephalothorax anterior and lateral regions, dorsal pleon and tailfan reddish brown to darkish red. Pereiopod pairs 2–5 reddish brown (Fig. 41C).

Habitat and Ecology. Peat bogs (Fig. 41A). Burrows are shallow due to the flooded soil in the winter and autumn. In the summer and spring, burrows reach 1 m depth; simple burrows without ornamentation and with chimney reaching up to 5 cm height (Fig. 41B). Burrows of Parastacus manezinho sp. nov. are of type 2 according to Horwitz and Richardson’s (1986) and considered a primary burrower species based on Hobbs’ (1942) classification.

Distribution. Brazil: Santa Catarina ( Fig. 42 ).

Figures

FIGURE 30. Parastacus guapo Huber, Araujo & Ribeiro, 2022: living specimen in nature.

FIGURE 37. Parastacus heterochaelis sp. nov., habitat and living specimens. A—­ habitat, peatland in the municipality of Viamão, state of Rio Grande do Sul; B—­ chimney; C—­ male (right) and ovigerous female (left) living specimens caught in the same burrow; D—­ ovigerous female showing eggs attached to pleopods; E—­ living specimen. Scale bar: E—­ 1 cm.

FIGURE 38. Parastacus heterochaelis sp. nov., distribution in the state of Rio Grande do Sul, southern Brazil.

FIGURE 39. Parastacus manezinho sp. nov., holotype and paratypes: A—­ habitus, dorsal view (holotype, MZUSP 45369); B—­ cephalon, dorsal view (holotype, MZUSP 45369); C—­ cephalon, lateral view (holotype, MZUSP 45369); D—­ female pleonal somites, dorsal view (paratype 1, UFRGS 6489); E—­ first to third male pleonal pleura (holotype); F—­ first to third female pleonal pleura (paratype 1, UFRGS 6489); G—­ tailfan (holotype, MZUSP 45369). Scale bars: A—­ 10 mm; B, E, F, G—­ 5 mm; C—­ 2 mm.

FIGURE 40. Parastacus manezinho sp. nov., holotype and paratypes: A—­ epistome (holotype, MZUSP 45369); B—­ thoracic sternites and gonopores (holotype, MZUSP 45369); C—­ thoracomere 8, caudal view (holotype, MZUSP 45369); D—­ antennal scale, lateral view (paratype 2, UFRGS 6490); E—­ mandible (paratype 2, UFRGS 6490); F—­ third maxilliped, ventral view (paratype 1, UFRGS 6489); G—­ third maxilliped, dorsal view (paratype 1, UFRGS 6489); H—­ first pereiopod, lateral view (holotype); I—­ first pereiopod, dorsal view (holotype, MZUSP 45369); J—­ second pereiopod, lateral view (holotype). Scale bars: A, J, C—­ 3,33 mm; B, I—­ 5 mm; F, G—­ 2,5 mm; E, D—­ 1,5 mm; H—­ 10 mm.

FIGURE 42. Parastacus manezinho sp. nov., distribution in the state of Santa Catarina, southern Brazil.