Belonectes stoddarti, Malyutina, Marina V. & Brandt, Angelika, 2009

Malyutina, Marina V. & Brandt, Angelika, 2009, Description of three new species of the deep-sea munnopsid genus Belonectes (Crustacea, Isopoda, Asellota) from the Weddell Sea, Southern Ocean, Zootaxa 2277, pp. 33-52 : 44-48

Belonectes stoddarti sp. nov.

( Figs 8–10 )

Material examined. Holotype. male (2.0 mm), ZMH K- 42037, ANDEEP III St. 80–9–E, 23 February 2005, 70°38.45’ – 39.18’S, 14°42.86’ – 43.43’W, 3100 m.

Paratypes. ZMH K- 42038, juvenile specimen (1.2 mm), same data as holotype.

Etymology. The species is named after marine biologist Michael Stoddart from Tasmania who has established and implemented the Census of the Antarctic Marine Life (CAML) within SCAR (Scientific Committee of Antarctic Research).

Description. Body ( Fig. 8 ) with fingerprint pattern on strong cuticle. Body length 2.4 width, height 0.35 length. Head length 0.4 width, length behind antennula insertion 0.2 antennula article 1 length; rostrum length 0.9 head length. Rostrum terminal width 0.7 basal width, rostrum basal width 2 times basal width of antennula. Cephalic keel expressed, clypeus 1.6 as wide and 0.5 as long as labrum. Pereonite 1 shortest laterally, longest medially, slightly broader than head, length 3.3 head length behind antennular insertions, pereonites 2–4 1.2, 1.3 and 1.3 times longer laterally than pereonite 1 respectively, anterior lobes of coxae of pereonites 1–4 not pronounced in dorsal view, with 2 lateral setae each. Natasome length 0.7 body length, width 1.3 head width; pereonite 5 lateral length equal to lateral length of pereonites 6 and 7 together; pereonites 6 and 7 of same length laterally. Lateral sutures between pereonites 5 and 6 equal in length to fused middle part, ventral bump of pereonite 5 with setae. Pleotelson slightly shorter than wide, length 0.3 body length, preanal ridge rather short, not projected backwards, rounded terminally, shorter than uropodal protopod.

Antennula ( Fig. 10 ) incomplete; article 1 reaching 0.7 rostrum length, length 1.3 width, with 1 distal broom seta, article 2 0.6 as long and 0.5 as wide as article 1; article 3 length 0.75 article 2 length, article 4 length 0.5 article 3 length.

Antenna incomplete ( Fig. 8 ): article 1 shortest, articles 2–4 subequal in length, scale on article 3 slender, half of article 4 length.

Left mandible ( Fig. 9 ) pars incisiva with 5 cusps; lacinia mobilis slender, length 0.7 pars incisiva length, with 4 teeth; spine row with 7 spines; condyle length 0.6 molar length; palp strong, slightly longer than mandibular body, width equal to distal molar process width, article 1 with 1 small distal seta, article 2 length 1.7 article 1 length, with 1 strong distal and 2 smaller lateral setae; article 3 weakly curved, with 1 long distal seta and row of smaller lateral setae.

Maxilla 1 ( Fig. 9 ) lateral endite 1.3 width of mesial endite, 2 inner spine-like setae distally serrated.

Maxilla 2 ( Fig. 9 ) mesial endite longest, lateral and middle endites subqual in length, middle endite with 2 equally long and 2 equally short distal setae, lateral endite with 2 equally long setae, 1 slightly shorter seta and 1 short inner seta distally.

Maxilliped ( Fig. 9 ) basis length 3.1 width, endite with 3 coupling hooks, distal margin with numerous slender setae, 2 broad fan and 2 serrated stout setae; palp inserted after 0.5 length of basis; palp article 2 lateral margin slightly convex, medial margin strait, both with 1 distal seta, lateral length 1.2 medial length, article 3 slightly shorter medially than article 2, medial margin slightly convex, dentate, with 8 setae; article 4 longer than article 3 laterally, medial lobe almost reaching article 3 medial margin, lobe width 2.4 article 5 width, medial margin with 7 setae; article 5 equal in length to article 4 laterally; with 1 lateral and 3 distal setae. Epipod slightly shorter than basis, length 3 width.

Pereopods incomplete, bases only ( Fig. 10 B). Pereopod 1 basis shortest, bases 2-4 of the same length, subequal to height of pereonites 1 and 2.

Pleopods ( Fig. 10 ): Male pleopod 1 length 2.8 width, distal margin almost not bent ventrally, medial lobes rounded, slightly longer and narrower than triangular lateral lobes, each with 4 distal setae. Pleopod 2 protopod length 1.7 width, distolateral part enlarged, bent dorsally with ventral keel bearing 4 small setae, distolateral margin with 7–8 setae, stylet length 0.4 protopod length, sperm duct open at midlength of stylet; exopod slender, width 0.3 endopod width. Pleopod 3 protopod half as long as endopod, endopod length 1.2 width, distal plumose setae length 0.7 endopod width; exopod 1.4 as long and 0.2 as wide as endopod, with many tiny simple lateral setae and distal simple seta, distal article length 0.4 proximal article length. Pleopod 4 endopod length 1.5 width, exopod 0.4 as wide and as long as endopod, distal plumose seta length 0.4 exopod length. Pleopod 5 length 1.9 width.

Uropod ( Fig. 10 ) length 0.15 pleotelson length. Protopod length 1.3 width, with 1 distolateral and 4 distomedial setae, endopod length 3.8 width, and 1.5 protopod length, with 2 spine-like sensory setae and 4 simple distal setae; exopod 0.5 of endopod length and width, with 1 spine-like sensory and 3 simple small distal setae.

Remarks. Belonectes stoddarti sp. nov. differs from other species of the genus by the expressed fingerprint pattern of the cuticle and the shape of the distal margin of the male pleopod 1: the medial lobes are narrow, rounded and slightly longer than the broad triangular lateral ones. The medial lobe of maxilliped palp article 4 of the new species is the broadest in comparison with that in other species: in B. stoddarti its width is 2.4 of article 5 width, whereas in B. parvus this ratio is 2.2 and in B. grasslei – 1.3. B. stoddarti sp. nov. has a relatively long exopod: the length ratio of endopod/exopod is 0.5 in B. stoddarti , in B. parvus it is 0.25 and in B. grasslei it is 0.20.

Distribution. The species is only known from the type locality: the eastern slope of the Weddell Sea, 3100 m depth.

Figures

FIGURE 8. Belonectes stoddarti sp. nov., male, holotype, ZMH K- 42037: A, body dorsal views; B, body lateral view; juvenile female, paratype ZMH K- 42038: C, body dorsal views; B, body lateral view. Scale bar 1 mm.

FIGURE 9. Belonectes stoddarti sp. nov., male, holotype, ZMH K- 42037: left mandible, dorsal view, with enlarged parts, maxilla 1, maxilla 2 and maxilliped, with enlarged parts, ventral view. Scale bar 0.1 mm.

FIGURE 10. Belonectes stoddarti sp. nov., male, holotype, ZMH K- 42037: pleopods 1 - 5, uropod and antennula; juvenile female, paratype ZMH K- 42038: antennula. Scale bar 0.1 mm.