(Figs. 18, 37, 38)
Etymology. In honour of Dr. Richard V. Dingle for his important contribution to the knowledge of deepsea fossil and recent Ostracoda, especially from the southeastern Atlantic.
Material: 5 live specimens. Holotype: 1 A F (SNB 0253), ANDEEP III, # 16 – 11, ZMH K 41289. Paratypes: 1 A F (SNB 0095), ANDEEP III, # 16 – 11, ZMH K 41290; 1 A F (SNB 0093), ANDEEP III, # 16 – 7, ZMH K 41291; 1 A F (SNB 0250), 1 (A 1) (SNB 0252), ANDEEP III, # 16 – 10 –S, ZMH K 41292.
Distribution. Cape Basin, Southeastern Atlantic, 4686 to 4723m.
Measurements (Fig. 18). Holotype, LV –L 1.27mm, H 0.73mm; RV–L 1.26mm, H 0.64mm. Paratypes, LV –A F L 1.21–1.26mm, H 0.70–0.72mm; (A 1) L 1.02mm, H 0.60mm.
Diagnosis. LV outline subrectangular, with smoothly arched dorsal margin, maximum height posterior to midlength. RV subtrapezoidal with fairly straight anterodorsal margin and highly arched posterodorsal margin. LV and RV with slightly concave ventral margin and obtuse posterior angle. Podomere VI of AII wider than long, with 1 long and 1 mediumsized claws, 2 mediumsized setae and 1 tiny seta. MxI with 7 strahlen and 24 or 25 feathered setae. Vibratory plate of ApV with 4 or 5 strahlen and 10 setae. Fu with 2 short, 1 mediumsized and 2 long feathered setae. Genital lobe suboval with tubular internal process.
Description. LV outline subrectangular; with smoothly arched dorsal margin; steep posterodorsal margin; broadly rounded anterior margin; slightly concave ventral margin; maximum height posterior to midlength. RV subtrapezoidal; with fairly straight anterodorsal margin; sinuate posterodorsal margin; truncate anterior margin; concave ventral margin; maximum height at midlength. LV and RV with obtuse posterior angle. Maximum length inferior to midheight. Calcified inner lamella fairly narrow; zone of concrescence very narrow, with numerous straight marginal pore canals. Adductor muscle scars bythocypridid, occupying less than 1 / 3 of valve height.
AI very robust; with relatively short and very strongly sclerotized setae; podomeres II and III fused; chaetotaxy 1 (0/0), 2 (0/. 1)+ 3 (0/. 2), 4 (1 /0), 5 (. 2 /. 3), 6 (. 2 /. 3), 7 (0/0: 5). AII stout; with short podomeres III, IV and VI; exopodite with 2 long and 1 tiny setae; podomere VI wider than long, with 1 long and 1 mediumsized claws, 1 tiny seta, and 2 mediumsized setae; chaetotaxy 1 (0/0: 2 i), 2 (. 1 /0: 1 i), 3 (0/.2.1.1), 4 (0/. 2 r. 2), 5 (. 1.1 c./. 1.1), 6 (0/0: 1 r, 1 c,2,1c). Md with 3 feathered setae on the exopodite; masticatory process with 1 or 2 bifurcate and 3 or 4 trifurcate teeth and several short setae; chaetotaxy of palp 1 (. 1 /. 1: 1 i), 2 (. 1./. 1: 1 i), 3 (. 5./. 1: 2 3 i), 4 (. 2./0: 34). MxI with 7 strahlen and 24 or 25 feathered setae; ventral endite with 2 ventral setae and several broad, feathered, distal claws; other endites with 1 ventral seta each plus several simple distal setae; all setae of palp not feathered; palp chaetotaxy (.1.1.1./. 2.: 1 c). Vibratory plate of ApV with 4 or 5 long strahlen and 10 mediumsized setae; podomeres of ApV to ApVII robust, with long and feathered terminal claws; exopodite of ApVI and VII without or with 1 tiny seta; chaetotaxy of ApVVII ApV 1 (.1.1.0 2 /0: 1 i, 1), ApVIVII 1 (.1.1.1/0: 1 i), ApVVII 2 (. 2 /0), 3 (. 1 /0), 4 (. 1 /0), (0/0:2,1c). Fu with 2 short, 1 mediumsized, and 2 long feathered setae; one tiny seta between Fu rods. Genital lobe suboval with tubular internal process.
Remarks. The valves of Bythocypris richarddinglei sp. nov. differ from Bythocypris reniformis Brady, 1880 sensu Puri and Hulings (1976: Pl. 2.7–10, Fig. 1) and B. praerenis sp. nov. by the more rounded outline, greater height in relation to length, and larger size (LV L: 1.21 to 1.27mm, instead of 1.09mm) of the former species. The valves of Bythocypris [sic] reniformis recorded by Maddocks (1969, Fig. 45.J–M) from the southwestern Atlantic (Albatross, #2763, 24° 17 ’S, 42 ° 48 ’ 30 ’’W, 1227m) are larger (LV L: 1.52–1.61mm), and more subtriangular than those of the new species described herein, with the maximum height of LV and RV at midlength, instead of posterior to it. Bythocypris [sic] reniformis recorded by Maddocks (1969, Fig. 45.N–U) from the Mozambique Channel, Southwestern Indian Ocean (R. V. Anton Bruun, cruises 7 and 8, # 365 D, 23 ° 20 ’S, 43 ° 33 E, 695 475m) present more similar, rectilinear outline to B. richarddinglei sp. nov., but a more arcuate LV dorsal margin, and more rounded RV dorsal margin.
B. eltanina Maddocks, 1969, B. spiriscutica Maddocks, 1969, B. promoza Maddocks, 1973, Bythocypris mozambiquensis Maddocks, 1969, and B. polarsterni sp. nov. are more subtriangular than Bythocypris richarddinglei sp. nov.
Bythocypris elongata Brady, 1880, Bythocypris prolata Maddocks, 1969 are more elongated than B. richarddinglei sp. nov. Bythocypris affins affins Brady, 1886 (sensu Brady & Norman 1889: 242) is smaller and more elongate, with a more smoothly rounded posterior angle. Bythocypris affins madagascarensis Maddocks, 1969 is higher in relation to length and with the maximum height of LV at midlength instead of conspicuously posterior to it.