Doloria (Dolorietta) sextafiliformis Chavtur, Brandão & Bashmanov, 2012, sp. nov.

Doloria (Dolorietta) sextafiliformis sp. nov.

(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, 60º39.53´S – 53º56.96´W to 60º37.93´S – 53º56.86´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 5th 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 5th segment with 6 proximal and 4 distal filaments. Mandibula: dorsal margin of basale with 1 proximal bristle. Dorsal margin of 2nd endopodite segment with 25–26 bristles: 6 long, 4–5 medium-sized and 15 short bristles. Fifth limb: main tooth of 1st exopodite segment with 6 pectinate teeth and without a proximal process; 4th and 5th 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; 2nd claw stouter than 1st claw, 4th claw slightly more slender than 5th 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 11A–E). Length 3.83 mm. Greatest height about 80% of length (Fig. 11A). Carapace oval with rounded posterior margin, and fairly deep incisur with overhanging rostrum; surface smooth (Fig. 11A). 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. 11C, 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. 11D); posterior infold with a row pores along its posterior margin (Fig. 11B) and a raised list of tiny bristles.

Antennula (Figs 11F, G; 17A). 2nd segment with numerous clusters of minute spines along dorsal and ventral margins. 3rd segment with a subterminal ventral bristle, and a proximal dorsal bristle; 4th segment with a single ventral bristle (broken), and a dorsal bristle that is shorter than 5th segment. Sensory bristle on 5th segment with 6 long, proximal filaments, plus 5 distal filaments (tips broken) (Fig. 11G). Medial bristle of 6th segment fairly shorter than 5th segment. 7th segment: a-bristle longer than bristle of 6th segment; b-bristle with 2 short, proximal and 3 long, distal filaments; c-bristle with 8 long, proximal and 1 short, distal filaments. 8th 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 11H–J; 12A–E). Protopodite as long as exopodite and with fairly long, medial bristle (Fig. 12D). Endopodite 3-segmented (Fig. 12D–E): 1st segment with 4 proximal bristles (3 short and 1 long), and 1 long, distal bristle about as long as 2nd segment. 2nd segment bare. 3rd 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. 12C). Spine of 9th segment about 85% length of 8th segment. Bristle of 2nd segment (Fig. 11H–J) reaching 9th 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. 9th segment with 4 bristles, all with natatory setules, dorsal bristle shorter than others. Exopodite about 75% length of bristle on 3rd segment.

Mandibula (Figs 12F, 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 12G, 13A, 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. 13B). Exopodite reaching beyond end of 1st endopodite segment; with pointed tip hirsute at disto-dorsal margin, plus 2 bristles (1 medium-sized and 1 long) (Figs 12F, 13A). Endopodite (Figs 13C–E): ventral margin of 1st segment with 4 terminal bristles (1 short, 1 medium-sized and 2 long); dorsal margin bare; ventral margin of 2nd 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. 13E). 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. 13D).

Maxillula (Figs 14A, B; 15A; 16A–C). 1st and 2nd endites lost. 3rd 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 14A, B, 15A, 16A, B): 1st 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. 2nd 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 (16C) with 2 long distal bristles and a single shorter, marginal, plumose bristle.

Fifth limb (Figs 14C, D; 15B–F). Epipodial appendage with 71 plumose bristles. Protopodite with straight, relatively thick, sclerotized anterior process, with ball-like distal part on distal margin. 1st endite with 10 bristles (all with long setules). 2nd endite with 7 bristles (all with long setules). 3rd endite with 8 bristles (4 bristles with long setules and 4 pectinate bristles). Exopodite: anterior surface of 1st 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 3rd segment with 3 bristles (1 short, plumose and 2 long, simple bristles); outer lobe with 2 long, plumose bristles. 4th segment with 5–7 bristles. 5th segment slightly separated by suture from 4th segment, and with 2 bristles (1 plumose). 3rd to 5th segments hirsute.

Sixth limb (Fig. 16D, E). Epipodial appendage with 4–5 bristles (Fig. 16D). 1st endite with 4 plumose bristles (2 long, distal and 2 short, medial) (Fig. 16D). 2nd 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. 3rd endite with 5 plumose bristles (1 short and 4 long) (Fig. 16D). 4th endite with 6–7 bristles (5-6 plumose and 1 bare) (Fig. 16D). Distal segment with 27–29 bristles (Fig. 16E).

Seventh limb (Fig. 17B, 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. 17C). 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. 17D–G). Each lamella with 11 claws (Fig. 17D). 2nd claw stouter than 1st claw. 4th claw slightly more slender than 5th claw (Fig. 17E). Other claws decreasing in length and stoutness posteriorly along lamella. 1st claw with a lateral row of large teeth and with marginal small teeth (Fig. 17F). Other claws with marginal teeth only.

Medial eye (Fig. 17A). Large, pigmented.

Lateral eyes Absent.

Bellonci organ (Fig. 17A). Cylindrical.

Upper lip (Fig. 17A). 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 2nd exopodite segment of the antenna; (3) the number of filaments on sensory bristle of 5th 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 9th 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 2nd 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

3rd segment large basale, square tip and proxi- small basale, rounded tip and proximal bristle as long as length of 2nd mal bristle about ½ length of 2nd 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 5th segment. Antenna: H and I, bristle on 2nd 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, 1st exopodite segment; C, 2nd–9th 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, 2nd segment of endopodite; E, ventral bristles on 1st 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, 4th and 5th 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 1st 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 1st endopodite segment of maxillula; C, bristle near main tooth on 1st 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, 3rd–5th claws; F, 1st claw; G, posterior of body showing caudal furca without claws.