Leptostylis neleae, Mühlenhardt-Siegel, Ute & Lavrenteva, Anna V., 2015

Mühlenhardt-Siegel, Ute & Lavrenteva, Anna V., 2015, Selected species of the family Diastylidae (Cumacea, Peracarida, Crustacea) from the deep-sea of the NW Pacific, Zootaxa 3956 (3), pp. 345-373 : 356-361

Leptostylis neleae n. sp.

( Figs 7–9 )

Material. Holotype: preparatory female, ZMH: K 44236 ; (coll. 17.08.2012);

Type locality. NW Pacific, Kurile Kamchatka abyssal plains, 43° 2.78' N 152° 59.29' E, 5218–5221 m depth, cruise 223 with RV “Sonne” ( KuramBio ), station #7-10, (EBS #12-S), gear: epibenthic sledge.

Paratypes: #12-4: 15 manca, 11 subadult males with developing pleopods (one of them figured, ZMH: K 44237 ), 8 preparatory females (one of them holotype, one of them dissected, ZMH: K44238 ) + 2 thorax; ZMH: K 44239 ; #3-9: 20 mancas, 4 subadult males, 1 preparatory female, 1 female with empty brood pouch (damaged); ZMH: K 44240 ; #11-12: 2 mancas, 1 preparatory female, 1 subadult male; ZMH: K-44258; #5-10: 1 adult female with empty brood pouch; ZMH: K-44259

Additional material: #2-9: 1 carapace; MIMB 29179; #2-9: 1 carapace; MIMB 29180; #3-9: 2 mancas, 3 carapaces; MIMB 29181; #4-3: 1 ovigerous female, 2 females with marsupial plates, 2 mancas, 1 damaged manca, 1 pleon; MIMB 29182; #5-9: 1 female with marsupial plates; MIMB 29183; #7-9: 1 manca; MIMB 29184; #9-9: 3 mancas; MIMB 29185; #9-9: 1 subadult male; MIMB 29186; #11-9: 2 mancas; MIMB 29187; #12-4: 4 mancas, 1 carapace; MIMB 29188.

Etymology. The new species is dedicated in loving memory to Nele Siegel, a wonderful and enchanting friend of one of the authors (UMS). She died too early (2 November 2014).

Diagnosis. Slight impression in prolongation of carapace fissure marking a lateral elevation (not a carina); combined length of pleonite 6 and telson shorter than uropod peduncle; telson preanal part 1.5 times longer than postanal part.

Description. Based on holotype, preparatory female (ZMH: K 44236 ), 8.5 mm long ( Fig. 7 ).

Smooth carapace with dimples, slight impression in prolongation of carapace fissure marking an elevation (not a carina) on each side; pseudorostral lobes meeting in front of ocular lobe for a short distance (0.1 times of total carapace length); siphonal tube not protruding;ocular lobe roundish; eyes missing.

Antennal notch missing; anterolateral tooth not pronounced; anteroventral margin of carapace serrated.

Integument whitish, well calcified. Five free thoracic segments visible. Pleon slightly longer (1.2 times) than pereion.

Telsonic segment short, slightly wider than long (length to width: 0.8). Telson ( Fig. 9 , U) short, slightly longer than pleonite 6 (1.2 times); 0.4 times as long as uropod peduncle; preanal part concave seen from lateral, 1.5 times longer than postanal part.

Appendages: preparatory female (ZMH: K 44238 ), 7.7 mm.

Antenna 1 ( Fig. 8 , A1): relative length of peduncle articles 1 to 3: 41/26/33; basal article with fringe of hairlike setae along margins, one pappose and one broken setae at terminal edges; article 2 with long pappose seta at inner distal edge, article 3 with simple seta at inner distal edge; accessory flagellum as long as basal article of main flagellum, tri-articulated, middle article longest; main flagellum tri-articulated, two aesthetascs from middle of terminal article and end of penultimate article respectively, a long simple seta at terminal article.

Maxilliped 2 ( Fig. 8 , Mxp2): B/R ratio 0.8, relative length of articles I to D: 11/21/32 /24/12; basis with three serrulate setae on outer distal corner; merus with two pappose setae along inner margin; carpus with six plumose setae along inner margin and one pappose seta on outer distal corner; propodus with one strong and one slender pappose setae on proximal part and four plumose setae along inner margin, one simple seta on outer distal corner; dactylus with one strong terminal (unguis) and two slender subterminal setae.

Maxilliped 3 ( Fig. 8 , Mxp3): B/R ratio 1.3, relative length of articles I to D: 11/19/28 /20/22; basis with prolongation at outer distal margin, five teeth along inner distal margin, a fringe of hair-like setae along outer margin, three pappose setae at distal prolongation and five at distal inner margin; ischium and merus with one pappose seta at inner distal corner each, merus with one pappose seta at outer margin; carpus with one pappose seta at inner distal margin and two broken setae at outer margin; setae of propodus broken off; dactylus with terminal strong (unguis) and four subterminal simple setae; exopod present.

Pereiopod 1 ( Fig. 8 , P1): B/R ratio 0.6, relative length of articles I to D: 10/11/31 /35/13; basis with 14 teeth along distal half, seven hair-like setae along margins, two pappose seta at outer distal corner; ischium and merus with one hair-like seta at inner margin each; carpus with four hair-like setae along margins; propodus with eight simple setae along margins; dactylus with one strong terminal (unguis) and two subterminal simple setae; exopod present.

Pereiopod 2 ( Fig. 9 , P2): B/R ratio and relative length of articles I to D not given, basis and dactylus damaged; all articles except ischium with more or less strong simple setae; basis with three, merus with four, carpus with seven, propodus with two; exopod present (not figured, broken off during dissection); carpus second longest article after basis.

Pereiopod 3 ( Fig. 9 , P3): B/R ratio 1.2, relative length of articles I to D: 15/23/ 43/13/6; all articles except merus with thin, simple setae, basis with six, ischium with two, carpus with five, dactylus with three terminal setae more robust; rudimentary exopod present.

Pereiopod 4 ( Fig. 9 , P4): B/R ratio 0.6, relative length of articles I to D: 18/ 28/38/9 /7; carpus to dactylus with slender simple setae: carpus with three, propodus and dactylus with one on distal margin each; rudimentary exopod present.

Pereiopod 5 ( Fig. 9 , P5): B/R ratio 0.6, relative length of articles I to D: 17/ 21/49/8 /5; carpus with four slender simple setae and dactylus with terminal strong seta and one subterminal slender simple seta.

Uropods ( Fig. 9 , U), peduncle much longer than endopod (1.8 times) as well as pleonite 6 (2.6 times), with eight cuspidate setae along inner margin; exopod two articulated, shorter than endopod; endopod tri-articulated, proximal article longest, with cuspidate setae, one at proximal article, two at middle article and two subterminal at third article, one terminal simple seta.

Subadult male, 7.2 mm long, with two pairs of developing pleopods and swollen antenna 1. Similar to female.

Distribution. Kurile Kamchatka abyssal plains, 4830–5780 m.

Remarks. The new species has a very faint ridge on the carapace dorsolaterally behind the frontal lobe fissure, like many other Leptostylis species. Among these, it resembles the species Leptostylis antipus Zimmer, 1907 (Southern Oceans, 12 to 310 m) and L. profunda Jones, 1969 (Tasman Sea, 3580 m) as the length of the pleonite 6 plus the telson is shorter than the uropod peduncle.

However, in the female of the new species the telson is 1.2 times the length of the pleonite 6 whereas in the other two species mentioned it is shorter (0.7 to 0.8 times). Furthermore, taking into account the geographical distance to the two species mentioned, the erection of a new species is reasonable.

Figures

FIGURE 7. Leptostylis neleae n. sp.; habitus of preparatory female (above; ZMH: K 44236) and subadult male (below; ZMH: K 44237) in lateral view; preparatory female from dorsal (middle); scale bars: 1 mm.

FIGURE 8. Leptostylis neleae n. sp.; dissected paratype (ZIM: K 44238); A 1: antenna 1; Mxp 2: maxilliped 2; Mxp 3: maxilliped 3; P 1: pereiopod 1; scale bars: 0.5 mm.

FIGURE 9. Leptostylis neleae n. sp.; dissected paratype (ZIM: K 44238); P 2: pereiopod 2; P 3: pereiopod 3; P 4: pereiopod 4; P 5: pereiopod 5; U: pleonite 6, telson and uropods; scale bars: 0.5 mm.