Remyleucon, Mühlenhardt-Siegel, 2025

Mühlenhardt-Siegel, Ute, 2025, The cumacean family Leuconidae in the south-west Atlantic deep-sea basins obtained during the cruise DIVA 3 with RV Meteor (cruise No. M 79 / 1), Zootaxa 5716 (2), pp. 151-206 : 195-204

publication ID	https://doi.org/10.11646/zootaxa.5716.2.1
publication LSID	lsid:zoobank.org:pub:17F5F026-7451-46B5-8838-C1D5561C04FA
persistent identifier	https://treatment.plazi.org/id/9F2B0602-AF20-FFC2-72DA-B79F29D295B0
treatment provided by	Plazi
scientific name	Remyleucon
status	gen. nov.

Treatment

Remyleucon gen. nov.

Diagnosis. Dorsomedian line on carapace serrate up to half in male, in female: dorsomedian 15 teeth up to the end of carapace; pseudorostrum projecting anteriorly, pseudorostrum with little dorsal extra tip, pseudorostral lobes with anteroventral part hyaline, anterior margin of carapace smooth; antennal notch shallow, in front of ocular lobe in non-ovigerous females; A1 geniculate after basal article 1; male antenna 2 reaches past carapace but not beyond pereionite 3, flagellum not modified for grasping; exopods on pereiopods 1–3 in female, 1–4 in male; uropod endopod 2-articulated; adult male without pleopods.

Etymology: The new genus is dedicated to the author’s little black feline friend named Remy.

Remarks: Regarding the lack of pleopods in adult males this new genus resembles Alleoleucon, Austroleucon , Hemileucon , Heteroleucon , and Nippoleucon . The flagellum of the antenna 2 in the new genus is not modified for grasping, and extends past the carapace but not to the end of the pereion. In contrast, the flagellum is modified for grasping in Nippoleucon , the flagellum does not extend beyond the carapace in Heteroleucon and Alleoleucon, and the flagellum extends to the end of the pereion in Austroleucon and Hemileucon .

Type species: Remyleucon hyalorostris sp. nov.

( Figures 30–36 View FIGURE 30 View FIGURE 31 View FIGURE 32 View FIGURE 33 View FIGURE 34 View FIGURE 35 View FIGURE 36 )

Material:

Holotype preparatory female, ZMH: K 64960 View Materials ( 15 July 2009); SW Atlantic, Argentine Basin, FS “Meteor” cruise Me 79- 1, station # 533, 36° 00.20'S 49° 01.96'W; 4602 m depth; gear: EBS. GoogleMaps

Paratypes:

Argentine Basin

# 532—EBS: 2 adult males (one with pleon broken off), 5 subadult males, 22 non-ovigerous females,1 ovigerous female ( ZMH K 65002 View Materials ) .

# 533—EBS: 18 adult males (1 figured, ZMH K 64963 View Materials , 1 View Materials dissected 5, 4 mm, ZMH K 64964 View Materials ), 10 subadult males, 10 ovigerous females (1 dissected 5, 5 mm long, ZMH K 64961 View Materials ; most of them more or less slightly damaged), 125 preparatory females, 33 mancae, 1 exuvia of ovigerous female, 1 carapace only ( ZMH K 65003 View Materials ) .

# 534—EBS: 40 adult males, 10 subadult males, 1 juv. male, 144 non-ovigerous females, 11 ovigerous female (1 damaged), 101 mancae, 16 carapaces only ( ZMH K 65004 View Materials ) .

Etymology.—The new species is named after the hyaline anteroventral part of the pseudorostrum.

Diagnosis.—A striking character of the new species is the hyaline anteroventral part of the pseudorostrum.

Description.—based on holotype, preparatory female ( Fig. 30 View FIGURE 30 ), 5.8 mm long, (ZMH K 64960 View Materials ).

Carapace with dorsomedian serration of 15 teeth up to the end of carapace; no lateral teeth on carapace; pseudorostral lobes with anteroventral part hyaline, 0.3 times length of rest of carapace; siphonal tube not protruding; ocular lobe reduced; eye lenses absent;

antennal notch reaching backwards beyond level of ocular lobe; anterolateral tooth developed; anterior margin of carapace smooth; anteroventral margin of carapace serrate; integument whitish.

Five free thoracic segments visible, first slightly shorter than second to fifth; 0,75 times shorter than carapace including pseudorostrum.

Pleon as long as carapace plus free thoracic segments. Pleotelson 1.1 times longer than wide.

Appendages: ovigerous female ( 5.5 mm long, ZMH K 64961 View Materials )

Antenna 1 ( Fig. 31 View FIGURE 31 , A 1 View FIGURE 1 ): geniculated after basal article 1; relative length of peduncle articles 1 to 3:27/23/50; accessory flagellum small, main flagellum 3-articulated, basal article longest.

Left mandible ( Fig. 31 View FIGURE 31 , Md): with 2 setae on corpus mandibulae under lacinia mobilis, basis truncated; Maxilliped 2 ( Fig. 31 View FIGURE 31 , Mxp 2): B/R ratio 0.6, relative length of articles I to D: 11/26/34/21/8; on coxa proximally with 5 setae on rudimentary oostegite; basis with one strong pappose seta distally; ischium unarmed; merus with one strong pappose seta; carpus with 7 plumose setae; propodus with 8 simple setae along inner margin; dactylus with one strong terminal seta, 5 simple setae sub terminally.

Maxilliped 3 ( Fig. 31 View FIGURE 31 , Mxp3): B/R ratio 1.2, relative length of articles I to D: 8/25/28/22/17; basis with six pappose setae along inner margin, one simple seta proximally, 2 stronger simple setae distally, outer distal corner with 3 strong pappose setae; ischium unarmed; merus with one pappose seta; carpus with 2 pappose setae; propodus with one pappose seta, 2 simple setae; dactylus with one terminal simple seta, 3 simple setae sub terminally, one simple seta medially; exopod present, basal article with 2 teeth.

Pereiopod 1 ( Fig. 31 View FIGURE 31 , P 1 View FIGURE 1 ): B/R ratio 0.6, relative length of articles I to D: 9/18/31/19/22; basis with 9 pappose setae, 2 strong simple setae; ischium unarmed; merus with one simple seta; carpus with 3 pappose setae and one simple seta; propodus with 4 simple setae; dactylus with 8 simple setae; exopod present, basal article with one tooth.

Pereiopod 2 ( Fig. 31 View FIGURE 31 , P 2 View FIGURE 2 ): B/R ratio 0.5, relative length of articles I to D: 4/24/30/15/27; basis with 4 pappose and 4 simple setae; ischium with one pappose seta; merus with 4 pappose setae and one simple seta; carpus with 3 strong simple setae; propodus unarmed; dactylus with 2 pappose and 6 simple setae; exopod present.

Pereiopod 3: damaged.

Pereiopod 4 ( Fig. 32 View FIGURE 32 , P 4 View FIGURE 4 ): B/R ratio 0.9, relative length of articles I to D: 15/38/25/16/7; basis with 5 pappose setae; ischium unarmed; merus with one simple seta and 2 pappose setae; carpus with 2 long simple setae; propodus with one long simple seta; dactylus with one strong simple seta terminally.

Pereiopod 5 ( Fig. 32 View FIGURE 32 , P 5 View FIGURE 5 ): B/R ratio 1.1, relative length of articles I to D: 14/36/24/18/8; basis with one pappose, one compound seta, and 2 simple setae; ischium with one pappose seta, merus with 3 simple setae; carpus with 2 strong simple setae distally; propodus with 1 strong simple seta distally; dactylus with strong terminal seta.

Uropods ( Fig. 32 View FIGURE 32 , U): damaged, 2-articulated endopod slightly shorter than peduncle, exopods broken off. Peduncle with 6 cuspidate setae along inner margin; basal article of endopod with 6 cuspidate setae along inner margin, 1 small cuspidate seta on outer distal corner; distal article shorter than basal, with 4 cuspidate setae along inner margin, 2 cuspidate setae subterminally, 2 strong, broken setae terminally.

Adult male ( Fig. 33 View FIGURE 33 ) ( paratype, ZMH K 64963 View Materials ): anterior tip of pseudorostral lobes in dorsal view each with 1 small tooth, anterior margin serrate; antennal notch shallow, subrostral tooth reduced; dorsomedian line with 10 teeth extending posteriorly little more than half of carapace; exopods on pereiopods with basal article dilated.

Appendages of dissected paratype, adult male, 5.4 mm long ( ZMH K 64964 View Materials ) .

Antenna 1 ( Fig. 34 View FIGURE 34 , A 1 View FIGURE 1 ): relative length of peduncle articles 1 to 3:47/31/23; accessory flagellum less than half as long as basal article of main flagellum; main flagellum 3-articulated.

Antenna 2 ( Fig. 34 View FIGURE 34 , A 2 View FIGURE 2 ): flagellum reaching not beyond pereionite 3, few setae on each flagellum article; simple setae in peduncle article 4 and 5.

Left mandible ( Fig. 32 View FIGURE 32 , Md): with 3 setae on corpus mandibulae under lacinia mobilis, basis truncated.

Maxilliped 2 ( Fig. 35 View FIGURE 35 , Mxp2): B/R ratio 0.6, relative length of articles I to D: 9/30/30/21/10; basis with long and strong pappose seta; ischium and merus unarmed; carpus with 9 (12) setulate setae along inner margin; propodus with one strong pappose seta from proximal region and 11 setulate setae along inner and distal margin; dactylus with strong simple seta terminally.

Maxilliped 3 ( Fig. 35 View FIGURE 35 , Mxp3): B/R ratio 1.4, relative length of articles I to D: 9/16/34/28/14; basis with 8 pappose setae along inner, 1 pappose seta on outer margin and 3 long pappose setae on outer distal corner; ischium unarmed; merus with 2 pappose setae and one long pappose seta on outer distal corner; carpus with 5 pappose and one simple setae; propodus with one simple and 4 pappose setae; dactylus with one terminal simple seta, 3 long simple setae sub terminally; exopod present.

Pereiopod 1 ( Fig. 35 View FIGURE 35 , P 1 View FIGURE 1 ): B/R ratio 1.0, relative length of articles I to D: 8/21/28/21/20; basis with 14 pappose setae along margins, 2 strong simple setae on inner distal corner; ischium unarmed; merus with 2 pappose setae on inner and distal margins, one long pappose setae on outer distal edge; carpus with 2 pappose and 2 simple setae; propodus with one simple and one pappose seta; dactylus with one terminal simple seta, 3 long 2 short simple setae sub terminally and one short simple seta medially; exopod present.

Pereiopod 2 ( Fig. 36 View FIGURE 36 , P 2 View FIGURE 2 ): B/R ratio 0.9, relative length of articles I to D: 8/27/25/16/24; basis with 8 pappose setae; ischium unarmed; merus with one simple seta and 3 pappose setae; carpus with 2 strong simple setae; propodus unarmed; dactylus with 5 strong simple setae distally, 3 pappose setae sub terminally; exopod present.

Pereiopod 3 ( Fig. 36 View FIGURE 36 , P 3 View FIGURE 3 ): B/R ratio 1.2, relative length of articles I to D: 29/27/24/15/5; basis with 6 pappose setae; ischium with 1 simple and 1 pappose seta; merus with one pappose seta; carpus with one pappose seta and 2 strong simple setae; propodus with one strong simple seta; dactylus with one strong simple seta terminally; exopod present.

Pereiopod 4 ( Fig. 36 View FIGURE 36 , P 4 View FIGURE 4 ): B/R ratio1.0, relative length of articles I to D: 22/39/20/14/5 basis with 4 pappose setae; ischium unarmed; merus with one simple and one pappose setae; carpus with one pappose seta and 2 strong simple setae; propodus with one strong simple seta; dactylus with one strong simple seta terminally and one simple seta sub terminally; exopod present.

Pereiopod 5 ( Fig. 36 View FIGURE 36 , P 5 View FIGURE 5 ): B/R ratio 0.8, relative length of articles I to D: 18/38/24/15/5; basis with one pappose seta; ischium with one simple seta; merus with 2 simple setae; carpus with one pappose seta and 2 strong simple setae; propodus with one strong simple seta; dactylus with one strong simple seta terminally.

Uropods ( Fig. 36 View FIGURE 36 , U), peduncle 1.2 times longer than pleonite 6, with 7 simple setae along inner margin; exopod subequal in length to endopod; endopod 2-articulated, basal article of endopod half as long as uropod peduncle; first article with 7 setae along inner margin, 2.1 times longer than distal article; distal article with 6 setae along inner margin, 2 strong simple setae terminally, one short simple seta on outer corner.

Distribution: Argentine Basin, 4602 to 4608 m depth.

Remarks: The most striking character of the new genus and species is the hyaline anteroventral part of the pseudorostrum, a character new for the family. In males the ischium of pereiopod 3 is slightly longer than merus. Additional features are given in the remarks for the genus (see above).