Neonesidea keyseri Brandão, 2008, sp. nov.

? Neonesidea keyseri sp. nov.

(Figs. 18 –21)

Etymology. In honour of Dr. Dietmar Keyser, from the University of Hamburg, for his important contributions to Ostracodology and his careful supervision during my Ph. D. thesis.

Material: 2 live specimen, 2 RV, 1 LV. Holotype: 1 A F (SNB 0264), ANDEEP II, # 140–8–E, ZMH K­ 41361. Paratypes: 1 (A­?2) (SNB 0652), 2 RV, 1 LV, ANDEEP II, # 140–8, ZMH K­ 41362.

Distribution. Eastern Scotia Sea, Southern Ocean (Atlantic Sector), 2962 to 2965 m.

Measurements (Fig. 18). Holotype, LV, L 1.33mm, H 0.88mm, RV, L 1.35mm, H 0.86mm. Paratypes, LV, A L 1.32, H 0.86mm; J (A­?2) L 0.83mm, H 0.58mm.

Diagnosis. LV and RV subhexagonal, posterior angle acute, valve surface smooth, with numerous and long sensilla. LV with rounded dorsal, anterior and posterior margins, and straight ventral margin. RV with straight anterodorsal and ventral margins, and narrowly rounded anterior and posterior margins. AI with elongated podomere VII. Podomere VI of AII with 1 long, distally spatulate claw, 1 short seta, and 1 short fused seta, all simple. Vibratory plate of MxI with 2 strahlen and about 21 feathered setae; distal margin of palp of MxI with 1 cylindrical, distally feathered seta, and 1 simple seta. Vibratory plate of ApV with 3 strahlen and 10 feathered setae. Distal claw of podomere V of ApV­VII slightly spatulate. Fu with 7 setae, second longest, first also long, other 5 medium­sized.

Description. LV and RV subtrapezoidal, posterior angle acute, valve surface smooth, with very numerous and long sensilla. LV with rounded dorsal, anterior and posterior margins, and straight ventral margin. RV with more angulated outline than LV, with straight anterodorsal and ventral margins. Inner lamella narrow, vestibules constricted. Radial pore canals simple and with rim. Adductor muscle scars arranged in 3 horizontal rows, dorsal row with 2 scars, middle and ventral rows with 3 scars each. In dorsal view, carapace lozengeshaped with acute anterior and posterior angles, maximum width anterior to mid­length.

Legend: ? Neonesidea keyseri sp. nov.: A, G, N, holotype A F (ZMH K­41361, SNB 0264); B–D, H–L, M, subfossil paratypes (ZMH K­41362); E, F, paratype (A­?2) (ZMH K­41362, SNB 0652). Bythocypris praerenis sp. nov.: O, subfossil paratype (ZMH K­41329). Bythocypris sp. aff. B. malyutinae sp. nov.: P, A M (ZMH K­ 41304, SNB 0308). Bythocypris malyutinae sp. nov.: Q, A M (ZMH K­41294, SNB 0255). A, C–E, RV, Ev; B, F, LV, ev; G, valve surface with sensilla; H, RV, iv; I, LV, iv; J, adductor muscle scars; K, anterior hinge element of H; L, posterior hinge element of I; M, posteroventral margin (note the denticulation); N, RLV, dv; O–Q, radial pore canals. Scale bars: A–F, H, I, N, 500µm; G, J, M, 100 µm; K, L, 50 µm, O–Q, 5 µm.

? Neonesidea keyseri sp. nov. Legend:, Holotype, A F (ZMH K­41361, SNB 0264)., ApV;, ApVI;

C, ApVII; D, Fu. Scale bars: 100 µm.

AI with very long, distal setae, podomere VII very elongate; chaetotaxy 1(0/0), 2(.1/0), 3(.1/0), 4(0/0), 5(.2/.2), 6(.3/.1), 7(0/0:4). AII elongate, especially podomere IV and V; exopodite with 1 long and 2 very short setae; podomere VI with 1 long, distally spatulate claw, 1 short seta, and 1 short, fused seta, all simple; chaetotaxy 1(0/0:2), 2(.1/0: 1i), 3(0/.3.2), 4(0/.2), 5(.1.2/.2), 6(0/0:1,1c,1fs). Md and MxI with several feathered setae and claws. Base of Md with 1 anterodorsal seta, masticatory process with 1 dorsal bifurcate, 4 medial trifurcate, and 1 ventral bifurcate teeth, plus several short setae; chaetotaxy of palp 1(0/.1.: 1i), 2(0/.2/ 1i), 3(.4./.1:1ic, 1i), 4(.2./0:1,1c,3). Palp of MxI with one ventral, long seta, 3 dorsal, medium­sized setae, and 2 distal, medium­sized setae, one of the distal setae modified, cylindrical, with feathered tip; vibratory plate with 2 strahlen and about 21 feathered setae. Vibratory plate of ApV with 3 strahlen and 10 feathered setae; chaetotaxy 1(.1.3.2/0), 2(.2/0), 3(.1/0), 4(.1/0), 5(0/0:1c,1). Chaetotaxy of ApVI 1(.1.1.1.1.1/0), Exopodite (0/0:2), 2(.1/0), 3(.1/0), 4(.1/0), 5(0/0:1c,1). Chaetotaxy of ApVII 1(.1.1.1.1/0), Exopodite (0/0:2), 2(.2/0), 3(.2/0), 4(.0/0), 5(0/0:1c,1). Long claws of podomere V of ApV to VII distally spatulate. Fu with 5 short setae and 2 medium­sized, distal setae.

Remarks. ? Neonesidea keyseri sp. nov. obviously belongs to a new genus, which is not described herein because of the low number of specimens available. ? Neonesidea keyseri is herein tentatively assigned to the genus Neonesidea due to its: (1) smooth fused claw of antenna II; (2) presence of 2 strahlen on the vibratory plate of maxilla I; (3) vibratory plate of appendage V with 4 strahlen, widely spaced from other setae; (4) muscle­scar pattern with 8 elongate scars arranged in three horizontal rows plus posterior inserted wedge. Otherwise, ? Neonesidea keyseri differs from the genus Neonesidea by its: (1) unstreamlined valve outline, (2) furca with 7 well developed setae, (instead of the last two very tiny). The distal antennal claw with sigmoid incision, typically present in males of Neonesidea, can not be observed herein, since no male is available.

? Neonesidea keyseri sp. nov. differs from other Neonesidea species by the subtrapezoidal outline, and the furca with seven well developed setae of the former species.

? Neonesidea keyseri sp. nov. is similar to, but differs from Bairdoppilata hirsuta (Brady, 1880) due to the elevated, conspicuous caudal process and concave posterodorsal margin of the last species (Puri & Huling 1976, Pl. 4.4–5). Another bairdoppilatan species similar to ? Neonesidea keyseri sp. nov., is Bairdoppilata villosa (Brady, 1880), this last species is higher in relation to length, with LV more subtriangular, with maximum height at mid­length (instead of anterior to mid­length), and more acute posterior angle; RV with relatively longer anterodorsal margin, more concave ventral margin and more acute posterior angle (Puri & Huling 1976, Pl. 2.1–4). Furthermore, ? Neonesidea keyseri sp. nov. differs from both bairdoppilatan species cited above on the short anterodistal claw of the podomere VI of antenna II, instead of the enlarged claw, diagnostic of the genus Bairdoppilata.