(Figs 11–17, Tab. 3)
Holotype. ZMH K- 41899, adult female (carapace length 3.83 mm); valves (both deformed), one limb of antennula, anterior body, upper lip, Bellonci organ and medial eye in alcohol, remaining appendages mounted on slide.
Type-locality. ANDEEP I, PS 61, ANT XIX/ 3, St. 46 – 7, epibenthic sledge, 60 º 39.53´S – 53 º 56.96´W to 60 º 37.93´S – 53 º 56.86´W, 2889 – 2886 m, 30 January 2002.
Paratypes. ZMH K- 42614, type locality, 12 juveniles in alcohol.
Etymology. The species name “ sextafiliformis ” from the Latin “ sexta ” (=six), “ fili ” (=filament), and “ formis” (=form) refers to number of filaments on sensory bristle of 5 th segment of the antennula.
Diagnosis. Adult female. Carapace: length 3.83 mm; infold behind rostrum with 14 short and 5 long bristles forming a vertical row. Antennula: sensory bristle of 5 th segment with 6 proximal and 4 distal filaments. Mandibula: dorsal margin of basale with 1 proximal bristle. Dorsal margin of 2 nd endopodite segment with 25–26 bristles: 6 long, 4–5 medium-sized and 15 short bristles. Fifth limb: main tooth of 1 st exopodite segment with 6 pectinate teeth and without a proximal process; 4 th and 5 th exopodite segments separated by a suture, with 5–7 and 2 bristles, respectively. Sixth limb: epipodial appendage with 4–5 bristles. Seventh limb: tip with a comb of 27 teeth; limb with 28 distal and 40 proximal bristles. Furca: each lamella with 11 claws; 2 nd claw stouter than 1 st claw, 4 th claw slightly more slender than 5 th claw. Lateral eyes: absent. Bellonci organ: Organ cylindrical with finger-like process at tip. Anterior body: surface slightly concave at middle.
Description of adult female. Carapace (Figs 11 A–E). Length 3.83 mm. Greatest height about 80 % of length (Fig. 11 A). Carapace oval with rounded posterior margin, and fairly deep incisur with overhanging rostrum; surface smooth (Fig. 11 A). Infold broad anteriorly, narrow ventrally and slightly broader posteriorly. Infold posterior to rostrum with about 14 short bristles (similar in structure similar to those of D. antarctica) and 5 long bristles (3 are double and 2 simple type) arranged in a vertical row (Fig. 11 C, E); around inner margin of incisur are 3 more long bristles; anterior infold with 3 tiny, spine-like bristles; antero-ventral infold lacks pores but has about 67 to 70 pairs of unequal bristles (Fig. 11 D); posterior infold with a row pores along its posterior margin (Fig. 11 B) and a raised list of tiny bristles.
Antennula (Figs 11 F, G; 17 A). 2 nd segment with numerous clusters of minute spines along dorsal and ventral margins. 3 rd segment with a subterminal ventral bristle, and a proximal dorsal bristle; 4 th segment with a single ventral bristle (broken), and a dorsal bristle that is shorter than 5 th segment. Sensory bristle on 5 th segment with 6 long, proximal filaments, plus 5 distal filaments (tips broken) (Fig. 11 G). Medial bristle of 6 th segment fairly shorter than 5 th segment. 7 th segment: a-bristle longer than bristle of 6 th segment; b-bristle with 2 short, proximal and 3 long, distal filaments; c-bristle with 8 long, proximal and 1 short, distal filaments. 8 th segment: d- and e-bristles bare and slightly longer than b-bristle; g-bristle longer than f-bristle, both with 8 long, proximal and 1 short, distal filaments.
Antenna (Figs 11 H–J; 12 A–E). Protopodite as long as exopodite and with fairly long, medial bristle (Fig. 12 D). Endopodite 3 -segmented (Fig. 12 D–E): 1 st segment with 4 proximal bristles (3 short and 1 long), and 1 long, distal bristle about as long as 2 nd segment. 2 nd segment bare. 3 rd segment with long, distal filament slightly longer than endopodite. Exopodite: basal spines present on segments 3 to 9 (spines not bifurcate at tip); spines on distal segments longer than those on proximal segments (Fig. 12 C). Spine of 9 th segment about 85 % length of 8 th segment. Bristle of 2 nd segment (Fig. 11 H–J) reaching 9 th segment, with 0–5 proximal spines and 12–13 distal teeth along ventral margin, and about 0–7 spines on dorsal margin. Natatory setules present on bristles on segments 3 to 8. 9 th segment with 4 bristles, all with natatory setules, dorsal bristle shorter than others. Exopodite about 75 % length of bristle on 3 rd segment.
Mandibula (Figs 12 F, G; 13). Coxale endite strongly spinous, with 2 stout spines at tip (both with additional stout, marginal teeth) and minute peg between them; short bristle with blunt tip present at base of endite (Figs 12 G, 13 A, F). Basale: dorsal margin with 1 short, proximal bristle, 1 long, distal bristle and 2 long, terminal bristles; ventral margin with 3 medium-sized a-bristles (usual short bristle absent); 3 b-bristles (2 short and 1 long); 1 medium-sized c-bristle; and 1 long d-bristle (Fig. 13 B). Exopodite reaching beyond end of 1 st endopodite segment; with pointed tip hirsute at disto-dorsal margin, plus 2 bristles (1 medium-sized and 1 long) (Figs 12 F, 13 A). Endopodite (Figs 13 C–E): ventral margin of 1 st segment with 4 terminal bristles (1 short, 1 medium-sized and 2 long); dorsal margin bare; ventral margin of 2 nd segment with 3 groups of bristles with 1, 1– 2 and 2 slender bristles in each group; dorsal margin with 6 long, 4–5 medium-sized and 15 short bristles (short bristles with fairly long spines along ventral margin) (Fig. 13 E). Distal segment with 2 long and 1 shorter claw-like bristles, and 4 simple bristles (1 medium-sized dorsal, and 2 long and 1 minute ventral); 2 long claw-like bristles with 2–3 proximal spines along ventral margin (Fig. 13 D).
Maxillula (Figs 14 A, B; 15 A; 16 A–C). 1 st and 2 nd endites lost. 3 rd endite with 5 bristles (4 setulous and 1 bare). Coxale with 1 stout, plumose bristle. Basale with 1 long and 2 medium-sized bristles. Endopodite (Figs 14 A, B, 15 A, 16 A, B): 1 st segment with 2 long, bare α-bristles; 3 β-bristles with marginal teeth (1 inner, short bristle, 1 outer, stout, long bristle, 1 short, middle bristle); cutting edge with small, rounded teeth. 2 nd segment with 3 pectinate a-bristles; 3 strongly pectinate b-bristles; 3 bare c-bristles; 3 d-bristles (2 bristles with 2 small teeth on middle of margin and 1 bare bristles). Exopodite (16 C) with 2 long distal bristles and a single shorter, marginal, plumose bristle.
Fifth limb (Figs 14 C, D; 15 B–F). Epipodial appendage with 71 plumose bristles. Protopodite with straight, relatively thick, sclerotized anterior process, with ball-like distal part on distal margin. 1 st endite with 10 bristles (all with long setules). 2 nd endite with 7 bristles (all with long setules). 3 rd endite with 8 bristles (4 bristles with long setules and 4 pectinate bristles). Exopodite: anterior surface of 1 st segment with 1 proximal bristle (with marginal setules), and 3 distal bristles (longest bristle with long, proximal setules and distally pectinate, others with long setules). Main tooth consists of 6 pectinate teeth, proximal process absent, and 1 spinous bristle (with about 3–4 middle teeth). Inner lobe of 3 rd segment with 3 bristles (1 short, plumose and 2 long, simple bristles); outer lobe with 2 long, plumose bristles. 4 th segment with 5–7 bristles. 5 th segment slightly separated by suture from 4 th segment, and with 2 bristles (1 plumose). 3 rd to 5 th segments hirsute.
Sixth limb (Fig. 16 D, E). Epipodial appendage with 4–5 bristles (Fig. 16 D). 1 st endite with 4 plumose bristles (2 long, distal and 2 short, medial) (Fig. 16 D). 2 nd endite with 4–6 plumose bristles (2–3 long, distal and 3 short, medial), and 0–1 bare spine-like bristle close to distal bristles. 3 rd endite with 5 plumose bristles (1 short and 4 long) (Fig. 16 D). 4 th endite with 6–7 bristles (5-6 plumose and 1 bare) (Fig. 16 D). Distal segment with 27–29 bristles (Fig. 16 E).
Seventh limb (Fig. 17 B, C). Tip with comb of 27 teeth; proximal teeth shorter than distal teeth and with rounded ends; middle tooth longer than others and recurved. Stout triangular, bare tooth present opposite to comb (Fig. 17 C). Limb with 28 distal bristles (17 dorsal and 11 ventral) with 1 to 7 bells, and 40 proximal bristles (20 dorsal and 20 ventral) with 5 to 7 bells.
Furca (Fig. 17 D–G). Each lamella with 11 claws (Fig. 17 D). 2 nd claw stouter than 1 st claw. 4 th claw slightly more slender than 5 th claw (Fig. 17 E). Other claws decreasing in length and stoutness posteriorly along lamella. 1 st claw with a lateral row of large teeth and with marginal small teeth (Fig. 17 F). Other claws with marginal teeth only.
Medial eye (Fig. 17 A). Large, pigmented.
Lateral eyes Absent.
Bellonci organ (Fig. 17 A). Cylindrical.
Upper lip (Fig. 17 A). Lip consisting of unpaired, anterior part with glandular pegs along margin; 2 pairs of short tusks near middle and unpaired, hirsute posterior lobe; anterior and posterior pairs of tusks with one row of glandular pegs.
Anterior body surface slightly concave at middle, with medium-sized, rounded anterior process.
Eggs Single adult female collected with 16 eggs.
Comparisons. Doloria (Dolorietta) sextafiliformis sp. nov. resembles D. (Dolorietta) levinsoni, but differs in: (1) the type of double bristles on the anterior-ventral and ventral infolds of the carapace; (2) the arming of the bristle on the 2 nd exopodite segment of the antenna; (3) the number of filaments on sensory bristle of 5 th segment of the antennula; (4) the number of teeth and bristles on seventh limb; (5) shape of anterior body (Tab. 2). Additionally, this new species is close to D. (D.) sp. nov. 2 but differs in: (1) the shape of the basal spine on the 9 th exopodite segment of the antenna; (2) the Bellonci organ; (3) the anterior of the body.
Distribution. Recent. Only known from the type locality. Drake Passage, Scotia Sea, Atlantic Sector of the Southern Ocean. Deep bathyal (2333–2359 m).
carapace Length 4.37 mm 4.62–4.66 mm Infold behind rostrum 16 bristles forming a vertical row 21 bristles
dorsal margin of 2 nd endo- 6 long, 4 medium and 20 short bris- 7 long, 3 medium and 15 short brispodite segment tles tles
anterior margin of second seg- concave straight ment
3 rd segment large basale, square tip and proxi- small basale, rounded tip and proximal bristle as long as length of 2 nd mal bristle about ½ length of 2 nd segsegment ment
fifth limb Anterior process of protopodite ball-shaped tip usual rounded tip
Seventh limb with 37 distal and 39 proximal bristels 39 distal and 36 proximal
tooth opposite to comb with 2 small teeth forming row on with 3 small teeth forming row on each side and with convex proxi- each side and with straight proximal mal part part
Lateral eyes 20–22 ommatidia 27 ommatidia
tip of Bellonci nipple-like process sub-triangular
organ
sclerotized pro- relatively wide narrow
cess of shorter
lobe of copula-
tory limb
FIGURE 11. Doloria (Dolorietta) sextafiliformis sp. nov. (holotype female: ZMH K- 41899). Carapace: A, right valve, lateral views; B, infold on posterior part; C, anterior part, internal view; D, antero-ventral part, internal view; E, bristles on antero-ventral part. Antennula: F, whole limb (distal bristles not shown); G, bristle on 5 th segment. Antenna: H and I, bristle on 2 nd segment of exopodite; J, distal part of bristle figured in H.
FIGURE 12. Doloria (Dolorietta) sextafiliformis sp. nov. (holotype female: ZMH K- 41899). Antenna: A, whole limb, B, 1 st exopodite segment; C, 2 nd– 9 th exopodite segments; D, endopodite and parts of protopodite and exopodite; E, endopodite. Mandibula: F, distal part of exopodite; G, endite of coxale.
FIGURE 13. Doloria (Dolorietta) sextafiliformis sp. nov. (holotype female: ZMH K- 41899). Mandibula: A, whole limb; B, ventral margin of basale; C, endopodite; D, 2 nd segment of endopodite; E, ventral bristles on 1 st endopodite segment; F, distal part of coxale endite.
FIGURE 14. Doloria (Dolorietta) sextafiliformis sp. nov. (holotype female: ZMH K- 41899). Maxillula: A, basale, exopodite and endopodite (distal bristles not shown); B, distal part. Fifth limb: C and D, 4 th and 5 th exopodite segments.
FIGURE 15. Doloria (Dolorietta) sextafiliformis sp. nov. (holotype female: ZMH K- 41899). A, distal part of maxillula. Fifth limb: B, whole limb (bristles not shown); C, exopodite; D, distal part of limb; E, main tooth on 1 st exopodite segment; F, anterior process of protopodite.
FIGURE 16. Doloria (Dolorietta) sextafiliformis sp. nov. (holotype female: ZMH K- 41899). A and B, cutting edge on 1 st endopodite segment of maxillula; C, bristle near main tooth on 1 st exopodite segment of maxillula. Sixth limb: D, whole limb; E, main segment.
FIGURE 17. Doloria (Dolorietta) sextafiliformis sp. nov. (holotype female: ZMH K- 41899). A, anterior of body showing medial eye, Bellonci organ (peg at tip broken), antennula and upper lip. Seventh limb: B, distal part; C, process opposite comb. Furca: D, lamella; E, 3 rd– 5 th claws; F, 1 st claw; G, posterior of body showing caudal furca without claws.