Stenotanais leonardoi, Segadilha & Bird & Tavares, 2023
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https://dx.doi.org/10.3897/zse.99.103003 |
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lsid:zoobank.org:pub:CFCE08BC-6C73-47EA-807D-EB9C3F2547E5 |
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https://treatment.plazi.org/id/4148D462-1E56-49B4-A4EE-A8023D18C47F |
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lsid:zoobank.org:act:4148D462-1E56-49B4-A4EE-A8023D18C47F |
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Stenotanais leonardoi |
| status |
sp. nov. |
Stenotanais leonardoi sp. nov.
Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4
Material examined.
Holotype: Brazil - Santa Catarina State • neuter, length 1.9 mm; stn A8 R2, 0-2 cm; MZUSP 43545.
Paratypes: Brazil - São Paulo State • 1 neuter (dissected), length 2.1 mm; stn E8 R 3, 5-10 cm; MZUSP 43547 - Santa Catarina State • 1 male, length 0.9 mm; stn A8 R 3, 2-5 cm; MZUSP 43546 • 3 neuters; stn A8 R 1, 2-5 cm (1 dissected); MZUSP 43548 • 2 neuters; stn A8 R 2, 2-5 cm; MZUSP 43549 • 2 neuters; stn A8 R3, 0-2 cm; MZUSP 43550 • 1 neuter; stn A10 R 2, 2-5 cm; MZUSP 43551 • 1 neuter; stn A11 R3, 0-2 cm; MZUSP 43552 - Paraná State • 1 neuter; stn B7 R1, 0-2 cm; MZUSP 43553 • 2 neuters; stn B7 R 2, 2-5 cm; MZUSP 43554 • 1 neuter; stn B7 R 3, 2-5 cm; MZUSP 43555 • 1 neuter; stn B8 R 2, 2-5 cm; MZUSP 43556 • 1 neuter; stn B9 R 2, 5-10 cm; MZUSP 43557 - São Paulo State • 2 neuters; stn C7 R 1, 2-5 cm; MZUSP 43558 • 1 neuter; stn C7 R 2, 2-5 cm; MZUSP 43559 • 1 neuter; stn C7 R 3, 2-5 cm; MZUSP 43560 • 1 neuter; stn C7 R 3, 5-10 cm; MZUSP 43561 • 1 neuter; stn C8 R 1, 2-5 cm; MZUSP 43562 • 2 neuters and 1 juvenile; stn C8 R 2, 2-5 cm; MZUSP 43563 • 2 neuters; stn C9 R 1, 2-5 cm; MZUSP 43564 • 1 neuter; stn C9 R 1, 5-10 cm; MZUSP 43565 • 1 neuter; stn C11 R 1, 2-5 cm; MZUSP 43566 • 1 neuter; stn C11 R 2, 2-5 cm; MZUSP 43567 • 1 neuter; stn D8 R1, 0-2 cm; MZUSP 43568 • 2 neuters; stn E7 R 3, 2-5 cm; MZUSP 43569 • 1 neuter; stn E8 R 1, 5-10 cm; MZUSP 43570 • 2 neuters; stn E8 R 3, 2-5 cm; MZUSP 43571 • 2 neuters; stn E9 R 1, 5-10 cm; MZUSP 43572 - Rio de Janeiro State • 1 neuter; stn F7 R 1, 2-5 cm; MZUSP 43573 • 1 neuter; stn F7 R 2, 2-5 cm; MZUSP 43574 • 1 neuter; stn F7 R 2, 5-10 cm; MZUSP 43575 • 1 neuter; stn F7 R 3, 2-5 cm; MZUSP 43576 • 1 neuter; stn H7 R 2, 2-5 cm; MZUSP 43577 • 1 neuter; stn H10 R 2, 2-5 cm; MZUSP 43578 • 1 neuter; stn H10 R 2, 5-10 cm; MZUSP 43579 • 1 neuter; stn P5 R 3, 2-5 cm; MZUSP 43580.
Diagnosis.
Neuter. Cheliped fixed finger with two simple setae on cutting edge. Pereopods 2-3 carpus with long spine, longer than half length of propodus. Uropod basal article longer than pleotelson; exopod and endopod with subparallel margins; exopod slightly wider than endopod, longer than endopod article-1 (0.7 × endopod), with two flat and wide terminal setae.
Etymology.
The species is dedicated to the first author’s life partner, Leonardo Santos de Souza, who has supported and encouraged this author in her academic career.
Description.
Based on neuter holotype (MZUSP 43545) length 1.9 mm, dissected neuter paratype (MZUSP 43547) length 2.1 mm and male (MZUSP 43546) length 0.9 mm. Body (Fig. 1A View Figure 1 ) very slender, about 14 × L:W. Cephalothorax elongate 1.7 × L:W, 1.5 × pereonite-1, straight-sided, naked. Pereonites 1-6. All pereonites rectangular, longer than wide, parallel-sided; pereonite-1 1.3 × L:W; pereonite-2 2.3 × L:W; pereonite-3 2.4 × L:W; pereonites 4-5 2.0 × L:W; pereonite-6 shortest, 1.3 × L:W. Pleon (Fig. 1A View Figure 1 ) short, 0.2 × TBL, about as long as pereonites 5 and 6 combined, with five subequal pleonites. Pleotelson short, trapezoidal 0.6 × L:W, less than half-length of pleon.
Antennule (Fig. 2A View Figure 2 ) 0.6 × cephalothorax; article-1 about 0.4 × TL, 1.6 × L:W, with one simple seta and three distal PSS; article-2 1.8 × L:W, 0.8 × article-1, with two simple setae and one distal PSS; article-3 0.9 × L:W, 0.3 × article-2, with simple subdistal seta; article-4 2.6 × L:W, 1.9 × article-3, with simple subdistal seta and with aesthetasc, three simple and minute terminal setae. Antenna (Fig. 2B View Figure 2 ) article-1 fused with body; article-2 as long as wide, with one simple distal seta; article-3 1.5 × L:W, naked; article-4 2.8 × L:W, 2.2 × article-3, with three medial PSS and three simple distal setae; article-5 3.0 × L:W, 0.7 × article-4, with a distal seta; article-6 minute with five simple terminal setae.
Labrum (Fig. 2C View Figure 2 ) elongate, hood-shaped, covered by minute setae. Mandible (Fig. 2D-G View Figure 2 ) with acuminate molar process with three or four terminal spines; left mandible (Fig. 2D, E View Figure 2 ) incisor smooth, with five unequal teeth and smooth lacinia mobilis (separated from incisor by wide gap); right mandible (Fig. 2F, G View Figure 2 ) with three strong teeth on incisor process, molar broken off during dissection. Maxillule (Fig. 2H View Figure 2 ) endite with nine terminal spines (at least two serrate), outer margin with setule; palp broken off during dissection. Maxilla (Fig. 2I View Figure 2 ) ovoid and stout, but large relative to maxilliped.
Maxilliped (Fig. 2J View Figure 2 ) basis with one simple seta near articulation with palps, not reaching distal margin of endites; endites unfused, with rounded distal cusps and a short seta on distal edge; palp article-1 naked; article-2 with three inner and one outer setae; article-3 with three (two long) inner setae; article-4 with four inner setae and one subdistal outer seta. Labium and epignath not observed.
Cheliped (Fig. 2K View Figure 2 ) and sclerite calcified; basis with one minute dorsodistal seta and long posterior projection (lobe), not reaching pereonite-1; 3.6 × L:W; merus subtriangular, with ventral seta; carpus stout 1.4 × L:W, with ventral seta and one proximal and one dorsodistal setae, carpal shield large, well developed; propodus stout 0.9 × carpus, 1.5 × L:W, with two setae near dactylus insertion on inner side (one long and one short); fixed finger with two strong serrate ventral spines and one spine on distolateral margin; cutting edge with two simple setae, dactylus slightly shorter than fixed finger.
Pereopod-1 (Fig. 3A View Figure 3 ) stout; coxa annular, seta not observed; basis broad 2.2 × L:W, naked; ischium with seta (not drawn); merus short 0.8 × L:W, with one ventrodistal seta and long spine reaching carpus distal margin; carpus short 0.6 × L:W, about as long as merus, with ventrodistal spine and one spinule (microtrichial), dorsodistal with long spine and microtrichia; propodus short 1.9 × L:W, 2.3 × carpus, with convex inferior margin with ventrodistal spine, microtrichia and two spinules and dorsodistal minute seta; dactylus as long as unguis, together 0.8 × propodus.
Pereopod-2 (Fig. 3B View Figure 3 ) stout; basis broad 2.0 × L:W, with large dorsal PSS; ischium with one seta; merus 1.1 × L:W, with ventrodistal long spine reaching carpus distal margin; carpus short as long as wide, as long as merus, with ventral spinules and microtrichia, two unequal ventrodistal spines (one longer than half length of propodus) and dorsodistal spine; propodus short 2.0 × L:W, 1.7 × carpus, with convex inferior margin with ventrodistal spine, microtrichia and two spinules, dorsodistal minute seta; dactylus 0.7 × unguis, together 0.8 × propodus.
Pereopod-3 (Fig. 3C View Figure 3 ) similar to pereopod-2, except basis naked.
Pereopod-4 (Fig. 3D View Figure 3 ) basis broken during dissection, naked; ischium with two long seta (only one drawn); merus 1.2 × L:W, with two ventrodistal spines; carpus 1.6 × L:W, with one seta and three distal spines; propodus stout 2.8 × L:W, with two ventrodistal spines and robust dorsodistal seta; dactylus with double row of ventral spines, 1.9 × unguis, together as long as propodus.
Pereopod-5 (Fig. 3E View Figure 3 ) similar to pereopod-4, except basis 2.4 × L:W; 2.3 × L:W, with dorsodistal minute and robust setae; dactylus and unguis together 1.2 × propodus.
Pereopod-6 (Fig. 3F View Figure 3 ) similar to pereopod-5, except basis 1.9 × L:W; ischium with two long seta (only one drawn); propodus short 1.6 × L:W, with three robust dorsodistal setae (one long and two short); dactylus with larger ventral spines, 3.2 × unguis, together 0.9 × propodus.
Pleopod (Fig. 3G View Figure 3 ) basal article naked; exopod with at least four plumose setae on outer margin and one seta on inner margin; endopod with at least ten plumose setae on outer margin, large gap between most proximal.
Uropod (Fig. 3H View Figure 3 ) reflexed; basis long 2.3 × L:W, about 1.1 × pleotelson, naked; exopod (Fig. 3H View Figure 3 ") one-articled, somewhat wider than endopod, 0.7 × endopod, with long medial seta and tipped by two specialised stout setae; endopod (Fig. 3H View Figure 3 ') two-articled; article-1 with distal seta; article-2 with long medial seta, two PSS and two simple distal setae.
Male (Figs 1B View Figure 1 , 4A-C View Figure 4 ). The only specimen of a putative 'swimming male’ of this species has a pereon shorter than in female and a well-developed pleon (Fig. 1B View Figure 1 ), larger than in female, as long as the pereon. Antennule seven-articled (Fig. 4A View Figure 4 ), broader than female, with numerous aesthetascs. No functional mouthparts. Cheliped thinner than in female (Fig. 4B View Figure 4 ), propodus fixed finger and dactylus with sharp point. Pleopods strong, supported with long plumose setae (with more setae than female). Uropod biramous (Fig. 4C View Figure 4 ), endopod and exopod of two articles.
Type locality.
Santa Catarina State, Brazil; stn A8 R2, -27,29679714, -46,62516071 (1045 m).
Distribution.
Brazil: Santos Basin (Rio de Janeiro, São Paulo, Paraná and Santa Catarina States). Occurring on the lower slope and the São Paulo Plateau area, ranging from depths of 686 to 2410 m. This species was the most abundant (51 individuals), with 71% of the specimens found at 2-5 cm sediment layer (i.e. up to 25 × their body length).
Remarks.
This new species is similar to S. crassiseta from the NE Atlantic in having the propodus of pereopods 1-3 with a convex inferior margin bearing many spinules and the general shape of the uropod endopod, but is distinguished by: (1) the cheliped basis more slender 3.6 × L:W (2.9 × in S. crassiseta ); (2) the cheliped fixed finger with two simple setae on cutting edge (three in S. crassiseta ); (3) the pereopod-1 dactylus as long as unguis (0.8 × in S. crassiseta ); (4) the pereopods 2-3 carpus with long spine, longer than half length of propodus (about one third in S. crassiseta ); and (5) the uropod exopod one-articled and much longer than endopod article-1, 0.7 × endopod (exopod two-articled and as long as endopod article-1, 0.4 × in S. crassiseta ).
Stenotanais leonardoi sp. nov. also resembles S. macrodactylus from the Gulf of Mexico (NW Atlantic) mainly by the shape of uropod; however, it differs by a combination of characters including: (1) antennule 0.6 × cephalothorax (slightly shorter 0.8 × in S. macrodactylus ); (2) cheliped fixed finger with two simple setae on cutting edge (two 'spiniform setae’ in S. macrodactylus ); (3) pereopod-2 dactylus 0.7 × unguis (more than twice in S. macrodactylus ); and (4) pereopods 2-3 propodus with convex inferior margin with ventrodistal spine, microtrichia and spinules (only with ventrodistal spine in S. macrodactylus ). The new species has the cheliped fixed finger with strong serrate spines ventrally, which could have been overlooked by other authors (e.g. as 'strong spines’, Bird and Holdich (1984) or as 'robust spiniform setae’, Larsen (2005, 2011)).
The male is of the ‘swimming’ type with no functional mouthparts, shortened pereon and multi-articulate antennule with multiple aesthetascs. This specimen was found in the same sample as an individual of S. leonardoi (a neuter) and was identified as this species by chelipedal features, such as the basis with a long posterior lobe, a carpal shield and well-developed fixed finger with two strong serrate ventral spines and uropod rami with subparallel margins (not oar-shaped as in S. uropedon sp. nov.). Only one male specimen was sampled while 50 neuters were collected, demonstrating how “unbalanced” the sexual ratio can be in tanaidacean species. However, as with all 'swimming males’ and the rare matching of sexes, only with a molecular analysis can conspecificity be absolutely confirmed ( Błażewicz-Paszkowycz et al. 2014).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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