Bythocypris richarddinglei, Brandão, Simone N., 2008

Brandão, Simone N., 2008, New species of Bairdioidea (Crustacea, Ostracoda) from the Southern Ocean and discussions on Bairdoppilata simplex (Brady, 1880),? Bairdoppilata labiata (Müller, 1908) and Bythopussella aculeata (Müller, 1908) *, Zootaxa 1866, pp. 373-452 : 425-428

Bythocypris richarddinglei sp. nov.

( 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 (A­1) (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; (A­1) 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: 2i), 2(.1/0: 1i), 3(0/.2.1.1), 4(0/.2r.2), 5(.1.1c./.1.1), 6(0/0:1r,1c,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: 1i), 2(.1./.1: 1i), 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.:1c). 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 ApV­1(.1.1.0­2/0: 1i,1), ApVI­VII­ 1(.1.1.1/0: 1i), ApV­VII­2(.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, #365D, 23°20’S, 43°33E, 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.

Figures

FIGURE 1. Stations of the ANDEEP cruises containing Bairdioidea. Legend: Stations of the ANDEEP I cruise; Stations of the ANDEEP II cruise; Stations of the ANDEEP III cruise. For details on stations see Table 1.

FIGURE 18. Length: height scatter plot of the valves of Bythocypris richarddinglei sp. nov., Anchistrocheles weddellensis sp. nov., and? Neonesidea keyseri sp. nov.

FIGURE 37. Bythocypris richarddinglei sp. nov. Legend: A – F, holotype, A F (ZMH K­ 41289, SNB 0253). A, RV ev, B, LV ev, C, AI, D, AII, E, Md, F, MxI. Scale bars: A – B, 500 µm; C – F, 100 µm.

FIGURE 38. Bythocypris richarddinglei sp. nov. Legend: A – C, E, G, holotype, A F (ZMH K­ 41289, SNB 0253); D, F, H, paratype, A F (ZMH K­ 41290, SNB 0095); I, paratype, A F (ZMH K­ 41292, SNB 0250). A – B, ApV; C, ApVI; D – E, Fu; F – I, genital lobe. Scale bars: 100 µm.