Dutoitella richarddinglei Brandão, Stuhlmann, Vital & Brandt, 2016, sp. nov.

Dutoitella richarddinglei sp. nov.

(Figures 2, 9–14, Table 1)

Diagnosis. A Dutoitella species with sub-oval outline, angulate primary reticulation and lack of secondary reticulation. Dorsal margin carries four or five bullae. Anterior marginal rim conspicuous, and numerous blade-like or conical spines on the anterior and posterior margins.

Derivation of name. In honor of Richard V. Dingle for his outstanding contributions to ostracodology, micropalaeontology and palaeoenvironmental sciences.

Material. (see Tab. 1) Two “live” (=with soft parts) males, seven Subrecent valves.

1) HOLOTYPE— One male (SNB 0293) on two slides: dissected soft parts mounted in Hydromatrix permanent medium on a glass slide (ZMH K- 44858a); 1 right valve and 1 left valve on a micropalaeontological slide, both coated for SEM (ZMH K- 44858b).

2) PARATYPES (type locality)— 1 male (SNB 0294) on two slides: dissected soft parts mounted in Hydromatrix permanent medium on a glass slide (ZMH K-44859a); 1 right valve and 1 left valve on a micropalaeontological slide, both coated for SEM (ZMH K-44859b). 1 adult right valve, 1 juvenile right valve (ZMH K-44860).

3) PARATYPES (other localities)— (A) ANDEEP III, station 80-6: 1 left and 1 right valves on a micropalaeontological slide (ZMH K-44861). (B) ANDEEP III, station 81-9: 1 left and 2 right valves on a micropalaeontological slide (ZMH K-44862).

Stratigraphic and geographical occurrence. (localities 1 to 3 in Fig. 2 and Tab. 1) Quaternary and living. Scotia and Weddell seas, Atlantic Sector of the Southern Ocean, 2970 to 4384m depth.

Type locality. Recent and Subrecent. ANDEEP I cruise, PS 61, ANT-XIX/3, German Research Vessel Polarstern, station 129-2, Scotia Sea, Southern Ocean, 23.02.2002, epibenthic sledge (suprabenthic net) trawled from 59°52.55'S, 59°57.26'W, 3631m to 59°52.20'S, 59°58.63'W, 3637m.

Other localities. Recent. ANDEEP III cruise, 2005, PS 67, ANT-XXII/3, German Research Vessel Polarstern, stations 80-6 and 81-9, Northeastern Weddell sea, Southern Ocean (see Tab. 1 for details).

Description. In lateral view (Fig. 9), rounded anterior and posterior margins with numerous blade-like or conical spines and tubercles. Convex ventral margin, dorsal outline sinuous because of anterior and posterior cardinal angles and spines and tubercles. Anterior and posterior marginal rims conspicuous. Dorsal margin with four or five bullae. Ventrolateral ridge not conspicuous, terminating in a conical spine. There is a conspicuous, large, smooth subcentral tubercle, but no posterior node. Surface ornamentation conspicuous, angulate and homogenous across the lateral surface of the valves. Muri narrow but prominent. Ventral surface with only ventrolateral ridge, other longitudinal ridges absent.

In internal view (Fig. 10, 11.A), outline sub-ovate with wide zone of concrescence anteriorly and posteriorly. Hinge amphidont; all the elements are smooth. Muscle scar pattern consist of four elongate adductor scars, and bisected frontal scar.

Antennula with 6 articulated segments (Fig. 11.B). Segment I long, sub-rectangular without setae. Segment II long, sub-rectangular with 1 dorso-proximal, 3 ventral setae; barbulae present dorso-proximally and dorso-distally.

A–B, E–F, male holotype (ZMH K-44858b, SNB 0293); C–D, male paratype (ZMH K-44858b, SNB 0294). Subrecent. Southern Ocean, Weddell Sea, German Research Vessel Polarstern, ANDEEP III cruise, PS 67, ANT-XXII/3, station 80-6, 22.02.2005, Agassiz trawl deployed from 70°39.37'S, 14°43.51'W, 3095m to 70°40.48'S, 14°43.77'W, 2970m. G, Subrecent paratype (ZMH K-44861).

A–D, entire right and left valves. E–G, details of valve ornamentation, E, dorsal region. F, anterior region. G, posterior region.

Type locality. Recent. Southern Ocean, Scotia Sea, German Research Vessel Polarstern, ANDEEP I cruise, PS 61, ANT-XIX/3, station 129-2-S, 23.02.2002, epibenthic sledge trawled from 59°52.55'S, 59°57.26'W, 3631m to 59°52.20'S, 59°58.63'W, 3637m.

A–E, G–H, male holotype (ZMH K- 44858b, SNB 0293); F, Subrecent (A-1) paratype (ZMH K- 44860). A–F, left valves; A, F, entire valve; B, medial hinge element; C, posterior hinge element; D, anterior hinge element; E, adductor and frontal muscle scar pattern. G–H, male copulatory limbs and uropodal lamellae.

Type locality. Recent. Southern Ocean, Scotia Sea, German Research Vessel Polarstern, ANDEEP I cruise, PS 61, ANT-XIX/3, station 129-2-S, 23.02.2002, epibenthic sledge trawled from 59°52.55'S, 59°57.26'W, 3631m to 59°52.20'S, 59°58.63'W, 3637m. A, basis and palp (setae of palp segments I and II removed); B, palp segments I (long, plumose, distal seta removed, see D); C, palp segment II; D, long, plumose, distal seta of palp segment I. Exopodite missing.

Segment III short, sub-quadrate with 1 dorso-distal seta. Segment IV sub-trapezoidal with 2 dorso-distal and 1 ventro-distal setae. Segment V short, sub-rectangular with 2 dorso-distal claws and 1 distal seta. Segment VI subrectangular with 2 distal claws and one bifurcate seta (arrow in Fig. 11.B)

Segment I of antenna short with 3 minute, ventral setae. Segment II elongate, sub-rectangular without setae (Fig. 11.C). Suture between segments II and III conspicuous. Exopodite with a simple, medium-sized seta. Endopodite with 4 segments, segments 2 and 3 fused. Segment III (=endopodite segment I) short, subtriangular with 1 very long, ventral seta. Segment IV (endopodite segment II) with 2 ventro-distal claws. Segment V (endopodite segment III) with 2 ventro-distal claws and one dorsal, short seta. Segment VI (endopodite segment VI) with 1 long claw.

Mandibula (Fig. 12) consists of a sclerotized masticatory process (i.e. medial region of the coxa) with about 6 teeth (Fig. 12.A), 2 short, distal seta, and a segmented palp. Mandibular palp consists of a basis (basipodite of some authors), an exopodite (or vibratory plate) with several setae (missing in Fig. 12), and a 2-segmented endopodite (Fig. 12.A). Segment II (=palp Segment I, or basis) thick, irregular in shape: (1) ventrally with 2 medium-sized, simple setae, 1 short, simple seta, and 1 long, plumose seta; (2) distally with 1 medium-sized and one very long, plumose setae, 1 short, simple seta, and 3 long, simple setae (Fig. 12.B, 12.D). Segment III (=palp Segment II, or endopodite segment I) elongate, sub-rectangular with several ventral barbulae, one long, ventro-distal seta, one short, ventro-distal plumose seta, and 6 dorso-distal setae of variable lengths (Fig. 12.C). Segment IV (=palp Segment III, or endopodite segment II) with 2 plumose, long setae, and 1 medium-sized, simple seta (Fig. 12.A).

Maxillula (Fig. 13) basis with three endites (or masticatory lobes, or masticatory processes), a 2-segmented endopodite (=palp), and a well developed exopodite (or vibratory plate). The exopodite with about 15 “Strahlen” plus several dorso-proximal barbulae (Fig. 13.A). Endite I (dorsal) and II with around 5 setae each (Fig. 13.A). Endite III (ventral) with 1 long, distal seta (Fig. 13.B). Segment II (or segment I of palp), dorso-distally with 1 thick, long claw, 2 medium-sized claws, and 2 short setae (Fig. 13.C). Segment III (or segment II of palp) with 3 medium-sized setae. Palp considerably thicker than endites (Fig. 13.C).

Segment I of the fifth limb dorso-proximally with 2 medium-sized, simple setae and 1 shorter dorso-distal seta; ventrally with barbulae (Fig. 14.A). Segment II dorso-distally with 1 short seta. Segment III without setae. Segment IV distally with 1 long claw.

Segment I of sixth limb dorsally with 1 medium-sized, simple setae, and distally with 2 short setae (Fig. 14.A, 14.B). Segment II dorso-distally with 1 short seta. Segment III without setae. Segment IV distally with 1 long claw.

Segment I of seventh limb dorsally with 1 long seta; distally with 1 medium-sized, simple setae. Segment II dorso-distally with 2 short setae (Fig. 14.A). Segment III distally with 1 minute seta. Segment IV distally with 1 minute seta and 1 long claw.

Each uropodal lamella reduced to 2 medium-sized, simple setae.

Basal capsule of male copulatory limb sub-trapezoidal with a sharpened, distal end (Fig. 10.G–10.H). Labyrinth coiled and heavily sclerotized. Copulatory process short and sinuous. Distal lobe attached posteriorly to basal capsule and composed of one posterior, suboval part and one elongated ventro-proximal, elongated part.

Measurements. HOLOTYPE (ZMH K-44858b; SNB 0 293), adult male RV: length 1.08mm; height 0.63mm; LV length 1.11mm; height 0.70mm. PARATYPES (ZMH K-44861; SNB 0294), RV length 1.11mm; height 0.70mm; LV length 1.10mm; height 0.64mm. PARATYPE (ZMH K-44860), (A-1) LV length 0.93mm; height 0.59mm.

Remarks. Dutoitella richarddinglei sp. nov. has valves with more suboval outlines than Dutoitella atlantiformis, Dutoitella colesi, Dutoitella crassinodosa, Dutoitella dinglei, Dutoitella eocenica, Dutoitella lesleyae, Dutoitella mazziniae, Dutoitella mimica, Dutoitella neogenica, Dutoitella paradinglei, Dutoitella praesuhmi, Dutoitella symmetrica, Dutoitella spinosa, Dutoitella whatleyi. Additionally, Dutoitella richarddinglei sp. nov. is similar to Dutoitella suhmi, but the former shows an homogeneous, angulate secondary ornamentation, lacks the rounded tertiary ornamentation on the lateral surface, and shows a less conspicuous anterior marginal rim. Dutoitella richarddinglei sp. nov. differs from Dutoitella ayressi in its conspicuous dorsal tubercles. Dutoitella richarddinglei sp. nov. is very similar to Dutoitella cronini, but the latter shows ventrolateral blade-like tubercles, which are absent in the new species. Finally, Dutoitella richarddinglei sp. nov. is more elongate than D. spinaplana.