Leucon (Macrauloleucon) watlingi, Brito & Serejo, 2023

Brito, Ayrton Do Ramo & Serejo, Cristiana Silveira, 2023, Leuconidae Sars, 1878 (Crustacea: Cumacea) from the southwestern Atlantic, filling the distribution gap along the Brazilian coast, Zootaxa 5383 (2), pp. 101-134 : 117-120

publication ID	https://doi.org/ 10.11646/zootaxa.5383.2.1
publication LSID	lsid:zoobank.org:pub:996315A6-A209-4DF7-B59C-0B7662741F37
DOI	https://doi.org/10.5281/zenodo.10350627
persistent identifier	https://treatment.plazi.org/id/FE6C381F-86D2-40DC-B754-F2AF6E3B7DAE
taxon LSID	lsid:zoobank.org:act:FE6C381F-86D2-40DC-B754-F2AF6E3B7DAE
treatment provided by	Plazi
scientific name	Leucon (Macrauloleucon) watlingi
status	sp. nov.

Treatment

Leucon (Macrauloleucon) watlingi sp. nov.

( Figs. 1B View FIGURE 1 , 8 View FIGURE 8 , 9 View FIGURE 9 and 10 View FIGURE 10 )

Material examined. Holotype female, 3.6 mm, #SANSED7 D09- R1 (0–2), MNRJ 30544 View Materials .

Paratypes: female 4.9 mm, #HAB7 H6, MNRJ 28904 View Materials (dissected, lost inthe fire) ; female, 3.7 mm, #SANSED4 H06- R3 , (0–2) MNRJ 30543 View Materials (dissected) ; female, 1.9 mm, #SANSED1 C06- R3 (0–2) , MNRJ 30545 View Materials ; female, 2.3 mm, #SANSED1 D06- R2 (0–2) , MNRJ 30550 View Materials ; female, 4.2 mm, #SANSED2 E06- R3 (0–2) , MNRJ 30546 View Materials ; female (broken), notmeasured, #SANSED7A06- R1 (5–10) , MNRJ 30547 View Materials ; male (carapace), notmeasured, SANSED7 C07- R1 (0–2) , MNRJ 30548 View Materials ; male, 1.6 mm, #SANSED7 D06- R3 (0–2) , MNRJ 30549 View Materials ; female, 2.1 mm, #SANSED8 G06- R1 (0–2) , MNRJ 30551 View Materials .

Additional material (lost inthe fire): female, 2.6 mm, #HAB6 C7, MNRJ 28902 View Materials ; 3 females, 2.4–3.3 mm, male, 1, 8 mm, #HAB7 D6, MNRJ 28903 View Materials ; 2 females, 3.2 and 3.3 mm, #HAB8 A7, MNRJ 28906 View Materials ; 2 females, 3.1 mm, #HAB8 D6, MNRJ 28907 View Materials ; female, 3.3 mm, #HAB8 E6, MNRJ 28908 View Materials ; female, 1.5 mm, #HAB9 H7, MNRJ 28909 View Materials ; female, 1.8 mm, #HAB7 H6, MNRJ 28905 View Materials ; females, 1.8 mm, # AMB3 View Materials E5, MNRJ 28893 View Materials ; male, 3.5 mm, 2 females, 2.3 and 3.4 mm, # AMB3 View Materials F5, MNRJ 28894 View Materials ; 2 females, 1.4 and 1.5 mm, # AMB6 View Materials D5, MNRJ 28896 View Materials ; male, 2.9 mm, # AMB5 View Materials C5, MNRJ 28895 View Materials ; male, notmeasured, # AMB11 View Materials B5, MNRJ 28897 View Materials ; female, 2.9 mm, # AMB11 View Materials C6, MNRJ 28898 View Materials ; female, 3.4 mm, # AMB11 View Materials F10, MNRJ 28899 View Materials ; 2 females, 2 and 3.5 mm, # AMB12 View Materials D5, MNRJ 28900 View Materials ; female, 2.9 mm, # AMB12 View Materials F5, MNRJ 28901 View Materials .

Development. Females: mature longer than 3.7 mm, preparatory 3.6 mm, immature between 2.1 and 2.3 mm, manca shorter than 2.1 mm. Males: mature and preparatory unknown, second immature 3.5 mm, first immature 2.9 mm, manca shorter than 1.8 mm.

Type locality. Santos Basin, SP, Brazil, 25°39’59’’S – 45°05’01’’W; 695 m.

Distribution. Brazil: Santos Basin (RJ, SP, SC), Campos Basin (RJ), Espírito Santo Basin (ES); 381–3001 m.

Etymology. The name watlingi is in honor of Dr. Les Watling (University of Hawaii), an esteemed researcher in Cumacea studies and a great reference in Leuconidae taxonomy.

Diagnosis. Pseudorostrum less than half carapace length, unarmed or with very small dorsal teeth and 2 ventral teeth. Frontal lobe with 2 teeth. Carapace ventral margin with serration of 4 teeth and small teeth laterally. Maxilliped 3 merus with 2 teeth on outer margin. Pereopod 2 ischium absent, carpus as long as propodus and dactylus together. Pereonite 2 and 3 unarmed. Uropodal endopod article 1, 3 times longer than article 2, article 2 with 3 teeth.

Description: Holotype preparatory female, MNRJ 30544.

Preparatory female, 3.6 mm. Carapace 1.5 times pereon length including pseudorostrum, with dorsal serrations of 2 small teeth on frontal lobe, frontal margin with serration of 4 teeth; pseudorostrum less than 0.5 times carapace length (measured from frontal lobe to posterior margin), 2 ventral teeth; branchial siphon extending 0.8 times carapace length; antennal notch small; anteroventral corner rounded with serration. Pereon with pereonites 2 and 3 unarmed. Pleon about 0.5 times total body length ( Figs. 1B View FIGURE 1 and 8 View FIGURE 8 ).

Paratype. Mature female, 4.9 mm, MNRJ 28904 View Materials (lost inthe fire) .

Antenna 1, not geniculate between articles 1 and 2; article 1, 0.7 times article 2 length, naked; article 2 as long as 3, with plumose setae; article 3 with plumose setae; main flagellum of 3 articles, article 1 naked, article 2 with 2 distal simple setae, article 3 with simple setae and 2 aesthetascs; accessory flagellum of 1 article, shorter than main flagellum article 1 ( Fig. 9 a View FIGURE 9 1 View FIGURE 1 ).

Antenna 2 rudimentary ( Fig. 9 a View FIGURE 9 2 View FIGURE 2 ).

Mandibles, basis truncate, incisor with 2 distal simple setae, lacinia mobilis with 4 cusps ( Fig. 8 View FIGURE 8 md).

Maxilla 1 with 2 endites, palp with one bristle (broken during dissection) ( Fig. 9 View FIGURE 9 mx1).

Maxilla 2 with 3 endites; broad endite with row of distal plumose setae; narrow endites with simple setae ( Fig. 9 View FIGURE 9 mx2).

Maxilliped 1, basis with long plumose seta; ischium absent; carpus with numerous setae on inner margin; propodus with 2 long plumose setae on outer margin and numerous simple setae on inner margin; dactylus with strong terminal and 2 subterminal plumose setae ( Fig. 9 View FIGURE 9 mxlp1).

Maxilliped 2, basis about 0.4 times length of remaining articles together, with plumose seta at inner distal corner; merus with plumose seta on distal inner margin; carpus with 10–11 plumose setae on inner margin; propodus with long plumose seta on outer margin and about 4–5 plumose setae on inner margin; dactylus with strong terminal and 3 subterminal simple setae ( Fig. 9 View FIGURE 9 mxlp2).

Maxilliped 3, basis 0.8 times length of remaining articles together, with plumose setae on inner margin, distolateral corner with 3 long plumose setae; ischium with cuspidate seta on inner margin; merus with 2 teeth and long plumose seta on outer margin and plumose setae on inner margin; carpus with plumose setae on inner margin and small simple seta at outer corner; dactylus with terminal simple seta and 3 subterminal simple setae; exopod, flagellum with 3 articles ( Fig. 9 View FIGURE 9 mxlp3).

Pereopod 1, basis 0.3 times length of remaining articles together, with plumose setae on inner margin, cuspidate setae at inner distal corner; ischium with tiny plumose seta; merus, carpus and propodus with simple and plumose setae; dactylus with long terminal simple setae and 3 pairs of subterminal simple setae; exopod, flagellum with 4 articles ( Fig. 10 p View FIGURE 10 1 View FIGURE 1 ).

Uropod, peduncle longer than pleonite 6 and shorter than rami with 4 setae on inner margin, last one cuspidate; endopod 2-articulate, article 1, 2.5 times article 2 length, with 5 cuspidate setae on inner margin, article 2 with 2 cuspidate setae and 3 teeth on inner margin, terminal cuspidate seta and subterminal plumose seta; exopod as long as endopod with 3 distal plumose setae ( Fig. 10 u View FIGURE 10 ).

Paratypes, mature female, 3.7 mm, MNRJ 30543 View Materials .

Mature female, 3.7 mm. Pereopod 2, basis about 0.6 times length of remaining articles together, with plumose setae; ischium absent; merus with plumose setae; carpus with 2 long plumose setae and cuspidate seta at outer distal corner; propodus naked; dactylus with 11 long plumose setae; exopod, flagellum with 4 articles ( Fig. 10 p View FIGURE 10 2 View FIGURE 2 ).

Pereopod 3, basis about 1.25 times length of remaining articles together, with plumose setae; ischium and merus with plumose setae; carpus and propodus with simple annulate setae; dactylus small with long simple annulate seta ( Fig. 10 p View FIGURE 10 3 View FIGURE 3 ).

Pereopod 4, basis about 1.1 times length of remaining articles together, with plumose setae; ischium and merus with plumose setae; carpus and propodus with simple annulate setae; dactylus small with long simple annulate seta ( Fig. 10 p View FIGURE 10 4 View FIGURE 4 ).

Pereopod 5, basis about 1.1 times length of remaining articles together, with plumose setae; ischium and merus with plumose setae; carpus and propodus with simple annulate setae; dactylus small with long simple annulate seta ( Fig. 10 p View FIGURE 10 5 View FIGURE 5 ).

Variation. Teeth on frontal lobe varies in size, may be very small or absent, some specimens may present very small dorsal teeth on pseudorostrum; branchial syphon may extend as long as carapace ( Fig. 9 h View FIGURE 9 ).

Remarks. Leucon (M) watlingi sp. nov. is most similar to L. (M) weddelli Ledoyer, 1993 inthe presence of pseudorostrum shorter than half carapace length, frontal lobe with 2 teeth, small lateral teeth on carapace, maxilliped 3 merus with 2 teeth on outer margin, pereopod 2 ischium absent. However, L. (M) watlingi sp. nov. differs from L. (M) weddelli Ledoyer, 1993 in the presence of a serration of 4 teeth on the frontal margin of the carapace (versus 2 strong teeth on the frontal margin of the carapace), pereopod 2 carpus as long as the propodus and dactylus together (versus pereopod 2 carpus longer than the propodus and dactylus together), pereonites 2 and 3 unarmed (versus pereonites 2 and 3 with dorsolateral teeth), uropodal endopod article 1, 3 times longer than article 2 (versus uropodal endopod article 1, 2.6 times longer than article 2) ( Ledoyer 1993; Mühlenhardt-Siegel 2011a; 2011b).

Furthermore, Leucon (M.) watlingi sp. nov. and L. (M) complexus Mühlenhardt-Siegel, 2011 have pereopod 2 carpus shorter than the propodus and dactylus together, a character that sets them apart from all other species of the subgenus. However, Leucon (M.) watlingi sp. nov. differs from L. (M) complexus in the presence of a frontal lobe with 2 teeth (versus 3 teeth), pereopod 2 lacks ischium (versus with ischium), uropodal endopod article 1, 3 times longer than article 2 (versus 2.5 times longer than article 2), article 2 with 3 teeth on the inner margin (versus article 2 with 1 shallow tooth on the inner margin) ( Mühlenhardt-Siegel 2011b).