Holodentata caeca Doti, Choudhury & Brandt, 2009, sp. nov.

Holodentata caeca sp. nov.

(Figs. 1–5, 10D)

Holotype: 1 ovigerous ♀ (1.6 mm), ZMH –41970, Weddell Sea; Station 133–2, (62°46.73’S, 53°02.57’W), depth 1584 m, 16 March 2005, RV Polarstern.

Paratypes: same locality as holotype: 25 brooding ♀ (1.2–1.5 mm), 87 preparatory ♀ (1.2–1.4 mm), 81 adult ♂♂ (0.9–1.4 mm) and 5 juveniles (0.8–0.9 mm) (ZMH –41971).

Diagnosis. Head anterior lobe rounded and curving upward in lateral view. Eyestalk long axis points laterally, without ommatidia. Lateral margin of pereonites 1–3 expanded into a subquadrate projection, 4 rounded and 5–7 produced into a single processes. Coxal plates produced into processes.

Description of ovigerous female (habitus description based on the holotype ZMH–41970, description of appendages on the paratype ZMH–41971). Length: 1.6 mm (Fig. 1A, B). Body width 0.6 length, widest at pereonite 3. Head width 2.2 length; anterior lobe rounded and curving upward in lateral view, margin with small denticles (broken off in the specimen illustrated, Fig. 1C). Apex of eyestalks denticulated, long axis pointing laterally, without ommatidia. Lateral margin of pereonites 1–3 expanded into a subquadrate projection, 4 rounded and 5–7 produced into single processes. Pereonite 1 about as long as pereonite 2, pereonite 2 <3> 4> 5<6 = 7 = free pleonite. Pereonite 5 shortest and pereonite 3 longest. Coxal plates produced into processes and denticulated, visible in dorsal view in all pereonites. Pleotelson width 1.2 length, marginally with 21–23 denticles on each side, apex pointed.

Antennula (Fig. 2B), article 1 largest, with 1 simple seta and 5 robust denticles on one side; article 2 0.7 length of article 1, with 4 broom and 3 simple setae; article 3 shorter than article 2, with 1 simple seta, article 4 shortest with 1 broom seta, article 5 slightly longer than article 6 without setation; article 6 with 4 simple setae and 1 aesthetasc.

Antenna (Fig. 2A), article 1 without setation, article 2 with 1 simple seta, article 3 with 5 robust denticles on each side and 3 denticles on distal margin, and 4 simple setae; article 4 shortest with 2 simple setae; article 5 subequal in length to article 6 with 1 broom and 2 simple setae; article 6 with 3 broom and 2 simple setae; flagellum with 8 articles, each article with numerous setae.

Right mandible (Fig. 2C), incisor process with 5 blunt cusps (proximal one quadrate); spine row with 5 serrate setae; molar process with 1 row of teeth and 1 seta on distal edge. Left mandible (Fig. 2D) as right except for: incisor process with a 3-cusped lacinia mobilis and spine row with 4 serrate setae; molar process without setation.

Maxillula (Fig. 2E), lateral lobe with 1 simple seta close to distal margin, 11 cuspidate setae distally (2 of these setulated) and 5 simple setae on lateral margin; mesial lobe with 4 large setulated setae distally and 4 slender simple setae on lateral margin.

Maxilla (Fig. 2F), lateral and middle lobe protruding distomedially, with 1 pectinated and 3 simple setae distally; mesial lobe with 2 pectinated, 1 setulated and 5 simple (with pore-bearing tip) setae on distal margin, 1 setulated seta and numerous simple slender setae on mesial margin.

Maxilliped (Fig. 3A), endite with 2 coupling hooks, distal margin with 3 simple and 2 setulated setae, ventral surface with 2 fan setae, dorsal with 3 setulated setae (see detail drawing). Epipod ovate, width 0.5 of length.

Pereopod 1 (Fig. 3B), basis longest article with 3 simple setae. Ischium 0.6 basis length, with 3 simple setae. Merus cup-shaped, with 6 simple setae and 2 cuticular combs. Carpus oval, 0.7 ischium length; dorsal margin with 2 simple setae distally; ventral margin with 2 robust and 5 simple setae and anterior surface with 1 cuticular comb. Propodus 0.9 ischium length, dorsal margin with 3 simple setae, ventral margin with 7 simple setae, anterior surface with 5 cuticular combs and 1 simple seta. Dactylus with 2 simple setae near distal end and 2 simple setae between unguis and supplementary claw, unguis slightly shorter than dactylus, supplementary claw 0.7 unguis length.

Pereopods 2–7 (Figs. 3C, D; 4). Bases with 2–4 simple setae. Ischia with 3–4 simple setae. Meri with 3–5 simple setae. Carpi with 2 simple setae at half length of article, and 3–5 simple setae and 1 broom seta on distal end, carpus of pereopod 7 with 6 cuticular combs. Propodi with 2–3 simple setae at half length of article, and 3–4 simple setae and 1 broom seta on distal end. Dactyli with 4–6 simple setae, unguis slightly longer than dactylus, supplementary claw absent.

Operculum (Fig. 5A) ovoid and pointed distomedially, width 0.9 length; lateral margins with several simple setae (many of these broken).

Pleopod 3 (Fig. 5B), endopod width 0.6 length, with 3 plumose setae distally. Exopod with 2 articles, distal one with 1 distal simple seta, which extends beyond the tips of the endopod setae.

Pleopod 4 (Fig. 5C), exopod reaching half length of endopod (endopod folded in the specimen illustrated).

Pleopod 5 (Fig. 5D) width 0.5 length.

Uropod (Fig. 5E) exopod 0.2 endopod length, with 2 simple setae distally; endopod with 3 simple setae subapically and 5 broom setae distally.

Description of adult male (paratype ZMH–41971). Pleopod 1 (Fig. 5F) maximum width 0.6 length; lateral lobes at 0.7 of its length from proximal end, each one with 6 simple setae; ventral surface with 4 simple setae (2 of these close to lateral margin).

Pleopod 2 (Fig. 5G), protopod width 0.4 length, with 18 simple setae on lateral margin. Endopod slightly surpassing protopod. Exopod bilobed.

Remarks. H. caeca sp. nov. is most similar to H. triangulata sp. nov.; the main differences between these two species are discussed in the remarks section of the latter one.

Distribution. Only known from type locality.

Etymology. The species name is Latin caeca meaning blind and refers to the absence of ommatidia.