Bythocypris malyutinae
Valves quite large; elongate and inequilateral (anterior margin more broadly rounded than posterior margin) in lateral view. External surface smooth, radial pore canals simple, with or without rim. LV with rounded outline, ventral margin straight, with upswung posterior angle, smoothly rounded dorsal margin. RV fairly sinuous in outline, especially the ventral margin; with truncate anterior margin, and slightly concave anterodorsal and posterodorsal margins. Females higher in relation to length than males. Adductor muscle scars bythocytherid, with 3 anterior (subdivided) scars and 1 posterior (subdivided) scar. Zone of concrescence fairly narrow with numerous short, straight marginal pore canals. Carapace subovate in dorsal view.
Antennula robust with not very long setae. Exopodite of antenna with 2 long and 1 short setae; segment VI of male with 1 long claw, 1 sexually dimorphic “6-segmented” medium-sized fused seta, and 2 or 3 simple medium-sized seta; segment VI of female with 1 long claw, 1 sexually dimorphic simple fused medium-sized claw, 2 or 3 medium-sized sim ple setae. Base of mandibula with 1 anterodorsal seta, masticatory process with 5 teeth plus several short setae; exopodite with 1 very long and 2 long feathered setae (one of the mandibles of one specimen with 1 very long and 3 long setae); segment IV of palp with 2 or 3 medium-sized setae and 2 mediumsized plumose claws. Maxillula with 5 to 9 strahlen (!) and 25 or 26 feathered setae; each endite with 1 to 4 plumose claws and around 5 setae; palp with 3 dorsal and 2 ventral setae, and 1 modified plumose claw. Fifth limb with 6 to 11 strahlen and 5 to 10 feathered setae, segment II might or might not be fused to segment III. Exopodite of sixth and seventh limbs with 2 medium-sized setae; one Ap of 1 specimen (SNB 0110) with 2 instead of 1 seta on segment 4. Furca with 2 rudimentary setae on dorsal margin; ventral margin with 4 or 5 short proximal setae, 1 medium-sized thin setae, 2 medium-sized robust setae, and 1 short distal seta. One short seta between furca rods. Genital lobe subtriangular, or suboval with tubularly extended distal margin. Male copulatory limb with coiled vas deferens; strongly sclerotized, sub-rectangular, arched, short proximal lobe; and subconical distal lobe armed distally with numerous chitinous spines.
Valves quite large, subovate to sub-triangular, inequilateral in lateral view. Segment VI of antenna of male with 1 long claw, 1 sexually dimorphic, “6-segmented”, medium-sized, fused seta, and 2 or 3 simple medium-sized setae; segment VI of antenna of female with 1 long claw, simple, 1 medium-sized, fused claw, and 2 or 3 medium-sized setae. Maxillula with 5 to 10 strahlen and around 26 feathered setae. Fifth limb with 6 to 11 strahlen and 5 to 8 feathered setae. Furca with 2 tiny setae on dorsal margin; 6 to 7 short setae, and 3 medium-sized setae (setae 2 and 4 longest) on ventral margin. Male copulatory limb with coiled vas deferens; strongly sclerotized, arched proximal lobe, and conical distal lobe, the last one armed distally with numerous chitinous spines.
Bythocypris eltanina Maddocks, 1969, B. mozambiquensis Maddocks, 1969, B. eltanina Maddocks, 1969, B. spiriscutica Maddocks, 1969 and B. promoza Maddocks, 1973.
Holotype, LV, L 1.88mm, H 1.02mm, RV L 1.88mm; H 0.88mm.
Paratypes, A LV, L 1.86–1.94mm, H 0.99–1.04mm; (A-1) LV, L 1.46–1.63mm, H 0.76–0.89mm; (A-2) LV, L 1.15–1.27mm, H 0.65–0.69mm.
Overall, B. malyutinae presents a similar valve outline to Bythocypris eltanina Maddocks, 1969 (except that the new species has a more rounded dorsal margin) but differs considerably in male copulatory limb (Brandão, 2008: Fig. 30.G–L; Maddocks 1969, Fig. 48.G).
B. malyutinae differs from: (1) B. reniformis, B. affinis, and B. prolata by its more subtriangular lateral view; (2) B. elongata in being higher in relation to length, with more smoothly rounded dorsal margin, and more sinuous LV outline; 3) B. spiriscutica has a more ovate outline, with less distinct posterior angle.
Bythocypris malyutinae Brandão, 2008 belongs to the Bythocypris mozambiquensis group, which includes B. mozambiquensis Maddocks, 1969, B. eltanina Maddocks, 1969, B. spiriscutica Maddocks, 1969 and B. promoza Maddocks, 1973. Some differences can be observed between B. promoza (Maddocks, 1972, Figs. 1–3) and B. malyutinae: (1) segment V of antenna in B. promoza conspicuously more elongate (Maddocks 1972: Fig.1C) than B. malyutinae sp. nov; (2) male modified seta of segment VI of antenna is “segmented” from the mid-length to the distal tip in B. promoza and is “segmented” just in the mid 1/3 of its length in B. malyutinae; (3) B. promoza lacks claws on mandibula palp, while B. malyutinae has 1 mediodistal claw on segment III and 2 distal claws at segment IV; (4) B. promoza lacks feathered setae on maxillula palp and endites; (5) the former sp. shows 12 strahlen (instead of 6 to 11) and 6 tiny posterior setae (instead of 5 to 10 medium-sized setae); (6) the former sp. has more elongate segments on fifth to seventh limbs; (7) B. promoza has fewer setae on furca (4 anterior, long setae plus 3 tiny setae, instead of 2 tiny dorsal, plus 8 or 9 setae on ventral margin); (8) the male copulatory limb of B. promoza lacks the large tubular spiny distal lobe.
For the soft part anatomy, I follow Horne et al., 2002 (Horne DJ, Cohen A, Martens K. 2002. Taxonomy, morphology and biology of Quaternary and living Ostracoda. In: Holmes JA, Chivas AR, editors. The Ostracoda. Applications in Quaternary Research. Washington, DC: American Geophysical Union. p 5-35.).
We use the following terms for the limbs/furca from anterior to posterior with alternative names in parenthesis:
antennula (antenna I, Aa, AI, first antenna)antenna (antenna II, AII, Au, second antenna)mandibula (mandible, Md)Maxillula (first maxilla, maxilla I, maxillule, MxI, Mxu)Fifth limb (ApV, Appendage V, first thoracic leg, maxilla, maxilla I, MxI, Mxu, maxilliped, clasper (for males), P1, second maxilla, walking leg)Sixth limb (ApVI, Appendage VI, first thoracic leg, second thoracic leg, P2, walking leg)Seventh limb (ApVII, Appendage VII, cleaning limb, P3, second thoracic leg, third thoracic leg, walking leg)Male copulatory limb (eighth limb, hemipenis, uropod). Whether the Male copulatory limb is homologous to a crustacean limb remains controvertial.Furca (caudal rami, Fu, furcal rami, uropods). The homology of the podocopan furca (anterior to the anus) to a myodocopan furca (posterior to the anus) remains controversial. Similarly, the homology of the ostracod furca to the furca of other crustaceans remains controvertial.
Antennula 1(0/0), 2(0/0:0-2i), 3(.2-3/0), 4(.0-2/.1), 5(.2-5/.2), 6(.2-3/.2), 7(0/0:5). Antenna 1(0/0:0-2i), 2(1/0:1i), 3(0/.3-4.1c,1,0-1r), 4(0/.2r.1c,1), 5(.1.1c,1/1,1r,1c), female-6(0/ :1c,2,1fc,1), male-6(0/:1c,1,1fs,1). Mandibula palp 1(0-1/1:1i), 2(.1.3-4/3:1i), 3(.4-5./.1:1-2,1c), 4(.1-3./0:2-3c,2). Fifth limb 1(.1.2-3.3/0), 2(0/.2), [+or not]3(0/1), 4(0/.1-2), 5(0/0:.1,1c,1). Sixth and seventh limbs 1(.1.1.2/0), 2(0/.2), 3(0/.1), 4(0/ .1-2), 5(0/0:1,1c,1).
Chaetotaxy formula follows Schornikov and Keyser (2004, The morphology and classification of Paradoxostomatinae (Ostracoda) from the nearshore zone of Madeira and the Canary Islands. Revista Española de Micropaleontologia 36: 57-81.) : "Figures without parentheses = segments numbered from proximal to distal; + = junction of segments. Figures within parentheses = number of setae: numerator = setae on dorsal margin; denominator = setae on ventral margin; integer figures = lateral, medial or apical armature elements, from dorsal to ventral. Figures within parentheses without indexes = normally development setae; r = rudimentary; c = claw-shaped seta or claws; s = sensory seta; p = plumose seta or ray; re = reflexed seta or ray; a = atriumwards ray; t = tooth or tooth-shaped seta; l or m = lateral or medial seta. A dot indicates the presence of an interval between setae or between segment ends; a colon indicates apical, lateral or medial setae; hyphen indicates variable elements. Commas are used for the sake of clarity e.g. to separate symbols by unarmed segments or setae without indexes."
(see an example of the chaetotaxy formula in the figure "EXAMPLE CHAETOTAXY" in this species page).
19 live specimens.
Holotype: 1 A M (SNB 0255), ANDEEP III, # 102–13–U, ZMH K-41294.
Paratypes: 1 A F (SNB 0263), ANDEEP II, # 134–4–E, ZMH K-41293; 1 A F (SNB 0245), 1 (A-2) (SNB 0304), ANDEEP II, # 134–4–S, ZMH K-41295; 1 (A-1) (SNB 0083), 2 (A-1) (SNB 0313-4), ANDEEP II, # 135–4–E, ZMH K-41296; 1 A, 2 (A-1) (SNB 0657), 1 (A-3), ANDEEP II, # 135–4–S, ZMH K-41297; 1 A F (SNB 0249), ANDEEP III, # 102–13–E, ZMH K-41307; 1 A F (SNB 0256), ANDEEP III, # 102–13–S, ZMH K-41308; 1 A F (SNB 0110), 1 (A-1) (SNB 0254), ANDEEP III, # 102–13–U, ZMH K-41309; 1 (A-1) (SNB 0257), ANDEEP III, # 102–13, ZMH K-41310; 1 A F (SNB 0273), ANDEEP III, # 110–8–E, ZMH K-41311; 1 (A-1) (SNB 0274), ANDEEP III, # 110–8–S, ZMH K-41312; 1 (A-1) (SNB 0111), ANDEEP III, # 110–8–U, ZMH K-41313.
A, adult; (A-1), (A-2), (A-3), juvenile instars; E (after a station number), epinet of the epibenthic sledge; F, female; H, Height; L, length; LV, left valve; M, male; RV, right valve; S (after a station number), supranet of the epibenthic sledge; SNB, specimen number as catalogued by the Brandão, S. N. (throught this number, it is possible to assign correctly the valves of a single specimen kept in a micropaleontological slide to their dissected appendages in a glass slide); V, valve; ZMH, Zoologisches Institut und Museum, University of Hamburg (Germany); ZMH K-, abbreviation of the Crustacea collection of the Zoologisches Institut und Museum, University of Hamburg (Germany); #, station number.
2008 Bythocypris malyutinae Brandão, sp. nov.: 412-420, Figs. 19.Q, 27, 28, 29.A–F, M, N, P–W, 30.A, B, G, H, M–R,31, 32.
In honour of Dr. Marina Malyutina (Institute of Marine Biology, FEB RAS, Russia), who is a specialist on deep-sea Isopoda, and also works on the ANDEEP material.
Bythocypris malyutinae Brandão, 2008 presents both bythocypridid and bairdiid characthers. It is a typical bythocypridid in: (1) carapace (subtriangular, thin and smooth), (2) antenna I with not very long setae; (3) genital lobe with short internal tube; (4) adductor muscle scars arranged in three anterior and one posterodorsal rows. Otherwise, the antenna II in B. polarsterni Brandão, 2008 presents one claw (in females) or seta (in males) fused to segment VI, which Maddocks (1969, 1972, 1973, 1976, 1991, 1995) considered to be diagnostic of the family Bairdiidae. Actually, females of Bythocypris eltanina Maddocks, 1969 also present a fused claw on this segment (Maddocks, 1969, Fig. 48.D). In the provided illustration of the male specimen (Maddocks, 1969: 48.C), it is unfortunately not possible to distinguish the insertion of the “segmented” claw from the other several setae the segment VI.
Weddell Sea, Southern Ocean (Atlantic Sector), 4059 to 4895m.
Brandão (2008)
Brandão, S. 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: 373–452,
(this publication can be freely downloaded from http://www.mapress.com/zootaxa/2008/f/zt01866p452.pdf)