Benthic myodocopid Ostracoda (Philomedidae) from the Southern Ocean Author Chavtur, Vladimir G. Author Keyser, Dietmar text Zootaxa 2016 4141 1 1 70 journal article 10.11646/zootaxa.4141.1.1 5f6dfb77-a313-4996-b2c8-1f944ab63ad7 1175-5326 260445 6033C3F3-85B8-4665-A7AF-7C0E4B230ABC Philomedes charcoti Daday, 1908 ( Figs. 28 H–K, 29, 30) 1908 Philomedes charcoti Daday ,: 9, Figs. 11 , 12 . 1912 Philomedes charcoti Daday, 1908 —Müller: 26 [key], 31. 1920 Philomedes charcoti Daday, 1908 —Skogsberg: 418. 1971 Philomedes charcoti Daday, 1908 —Kornicker: 171, Figs. 4 , 5 . 1975 Philomedes charcoti Daday, 1908 —Kornicker 236–238, Figs. 131, 133, 134, 135 (map). 1989 Philomedes charcoti Daday, 1908 —Hartmann: 234–235. 1991 Philomedes charcoti Daday,m 1908 —Hartmann: 212. Studied material (coordinates, depth and sediment see Appendix). 52th Russian Antarctic Expedition , Prydz Bay , station 2, sample 43: MIMB 18303 and 18 304— 2 adult females (2.02 and 2.05 mm ). Station 2, sample 44: MIMB 18305—adult female ( 1.87 mm ) and MIMB 1 8306—adult male ( 2.02 mm ). Station 10, sample 55: MIMB 18 307—immature male ( 1.72 mm ). Additional material . See Appendix. Diagnosis of female ( Kornicker 1975, with additional remarks ) Carapace : with truncate posterior and rounded postero-ventral corner, surface distinctly reticulate, length 1.71–2.05 mm . First antenna : 2nd joint with 2–3 setae, 1 ventral, 0–1 lateral and 1 dorsal. Second antenna : 1st joint of endopodite with 6 setae, 5 proximal and 1 distal; 2nd joint with 1 long ventral and 1 long terminal seta. Mandible : dorsal margin of basale with 3 setae, 1 near middle and 2 subterminal. Sixth limb : epipodite with 2–3 setae. Seventh limb : each limb with 15–18 setae, 4–5 distal and 10–13 proximal; 2 pegs present on opposite terminal comb. Caudal furca : each lamella with 9 (rarely) or 10 claws, main claws short, stout, often with rounded tips. Bellonci organ : 1- or 2-jointed, with pointed tip. Lateral eye : elongate, with 2 ommatidia. Anterior process (above upper lip): developed, with rounded tip. Diagnosis of male. Carapace : length 2.20 mm . First antenna : 2nd joint with 3 setae, 1 ventral, 1 lateral and 1 dorsal. Second antenna : 1st joint of endopodite with 4–5 setae, 3–4 proximal and 1 distal; proximal seta of 3rd joint about 3/4 of its length. Mandible : dorsal margin of basale with 3 setae, 1 near middle and 2 subterminal; coxale endite present. Sixth limb : epipodite with 3 setae. Seventh limb : each limb with 12–15 setae, 4–6 distal and 5–10 proximal; 2 pegs present on opposite terminal comb. Caudal furca : each lamella with 8 or 9 claws. Bellonci organ : 1-jointed, with rounded tip. Anterior process (above upper lip): undeveloped and slightly rounded. Supplementary description of adult female. Carapace. ( Fig. 29 A–C). Length 1.80–2.05 mm (in literature: 1.71–1.96 mm ). Carapace with truncate posterior and rounded postero-ventral corner. Infold on rostrum with 10–11 setae forming a row and 3 setae near incisure. Antero-ventral inside with 12–13 striations and 1–9 setae. Infold on caudal process with 2–8 short setae. Carapace with distinctly reticulate pattern. First antenna ( Fig. 29 E). Second joint with 3 setae, 1 dorsal, 1 lateral and 1 vertical. Second antenna ( Fig. 29 F, G). Endopodite: first joint with 5 proximal and 1 distal setae; second joint with 1 long spinous ventral seta and 1 subterminal short bare seta. Mandible ( Fig. 29 H). Basale: dorsal margin with 3 setae, 1 near middle and 2 subterminal; medial side with 6 setae, 3 pectinate and 3 usual type; lateral surface with 5 setae parallel to ventral margin; ventral margin usually with 2 distal setae. Endopodite: first joint with 4 ventral setae; dorsal margin of second joint with 2 setae in proximal group, 6 (rarely 5) setae in distal group and 1 seta between these groups; ventral margin with 2 setae in subterminal and 3 setae in terminal group. Sixth limb . Endite I with 1 or 2 terminal and 1 medial setae, endite II with 3 terminal and 1 medial setae, endite III with 8 terminal and 1 medial setae, endite IV with 7 (rarely 6) terminal and 1 medial setae, end joint with 16–18 setae; 2 or 3 setae present in place of epipodial appendage. Seventh limb . Each limb with 15–18 setae, 4–5 distal (usually 3+2 and rarely 2+2) and 11–13 proximal (5+6, 5+7 or 5+8) setae; each seta with 2–8 bells. Terminal comb with 12 teeth; 2 pegs present on opposite comb. Caudal furca ( Fig. 29 I). Limb with 10+10 or 10+9 claws. Claws 1–4 stout and short. Medial eye ( Fig. 29 D). Large, smooth. Bellonci organ ( Fig. 29 D). Elongate, 2-jointed with pointed tip. Upper lip ( Fig. 29 D). Ventrally hirsute, terminally with several glandular processes. Anterior process on body ( Fig. 29 D). Developed, rounded. Supplementary description of adult male. Carapace ( Figs. 29 J–L; 30 A): Length 2.20 mm . Carapace elongated and reticulated. Height subequal in anterior and posterior. Infold on rostrum with about 11 setae forming a vertical row and 2 setae placed near ventral margin of rostrum. Below incisure 1 minute seta is present. Anteroventral inside with 8 or 9 setae. Infold on caudal process with 3 or 4 spine-like minute setae. First anten na ( Fig. 30 C, D). Second joint with 3 setae, 1 thick and long ventral seta and 1 lateral and 1 dorsal short normal type setae. Sensory seta of fifth joint evenly tapered from base to tip (without knee in middle) and with 4 terminal filaments ( Fig. 30 D). Second antenna ( Fig. 30 E, F). Endopodite: first joint with 3 or 4 proximal and 1 distal setae; second joint with 2 muscle bands, one extends from first joint to posterior margin of third joint and another from middle of ventral margin of second joint to posterior margin of third joint ( Fig. 30 E); third joint with 4 terminal ridges (on both limbs); proximal seta about 4/5 length of this joint. Exopodite: distal margin of first joint bare; seta of second joint with 13 ventral spines ( Kornicker 1971: 24 spines ); ninth joint with 4 long and 2 short setae. Mandible ( Fig. 30 G–J). Coxale endite bifurcate above middle of its length ( Fig. 30 G, J) ( Kornicker 1971: bifurcate from base of endite ). Basale: dorsal margin with 3 setae, 1 near middle and 2 subterminal; medial side with 6 setae, 3 pectinate and 3 normal type ; lateral surface 4 setae parallel to ventral margin; ventral margin with 2 distal setae. Exopodite about 1/2 length of first endopodial joint or somewhat shorter. Endopodite: first joint with 4 ventral setae; dorsal margin of second joint with 2 setae in proximal group, 6 setae in distal group and 1 seta between these groups; ventral margin with 2 setae in subterminal and 3 setae in terminal group. Sixth limb . Endite I broken, endite II with 3 terminal and 1 medial setae, endite III with 8 terminal and 1 medial setae, endite IV with 6 or 7 terminal and 1 medial setae, end joint with 13–14 setae; 3 setae present in place of epipodial appendage. Seventh limb ( Fig. 28 J, K). Each limb with 13 setae (in literature: 12–15 setae), 4 distal (3+1) and 9 proximal (4+5) setae (in literature: 2+3 or 3+ 3 in distal group and 3+4 or 3+ 7 in proximal group). Terminal comb with 10 alate teeth ( Kornicker 1971: 13 teeth ) and 2 pegs on opposite comb. Caudal furca ( Fig. 30 K). Limb with 8+9 claws (in literature: 9+9 claws). Claws 1–4 relatively short. Copulatory appendage ( Fig. 30 K). Organ very small, about ¼ length of lamella of furca (shorter than that in specimen described by Kornicker 1971 ). Bellonci organ ( Fig. 30 B, C). Elongated, somewhat longer than first joint of first antenna, and with rounded tip. Supplementary description of A- 1 male . Carapace. Length 1.72 mm . First antenna . Second joint with 3 setae, 1 dorsal, 1 lateral and 1 ventral. Second antenna ( Fig. 28 I). Endopodite: first joint with 4 proximal and 1 distal setae; second joint with 1 long spinous and 2 short bare ventral setae; third joint with 1 midlength dorsal and 2 short terminal setae. Mandible . Basale: dorsal margin with 3 setae, 1 near middle and 2 subterminal; lateral surface with 4 setae parallel to ventral margin; ventral margin with 3 distal setae. Endopodite: first joint with 4 ventral setae; dorsal margin of second joint with 2 setae in proximal group, 6 setae in distal group and 1 seta between these groups; ventral margin with 2 setae in subterminal and 3 setae in terminal group. Sixth limb . Endite I broken, endite II with 3 terminal and 1 medial setae, endite III with 8 terminal and 1 medial setae, endite IV with 7 terminal and 1 medial setae, end joint with 14 setae; 2 setae present in place of epipodial appendage. Seventh limb . Each limb with 15 setae, 5 (3+2) in distal group and 10 (5+5) in proximal group; each seta with 2–5 bells. Terminal comb with 12 teeth; 2 pegs present on opposite comb. Caudal furca ( Fig. 28 L). Limb with 9+9 claws. Claws 1–4 relatively stout and short. Medial eye ( Fig. 28 H). Large, smooth. Bellonci organ ( Fig. 28 H). Elongate, 2-jointed with pointed tip. Upper lip ( Fig. 28 H). Ventrally hirsute, terminally with several glandular processes. Anterior process on body ( Fig. 28 H). Developed, rounded. Distribution and ecology . Antarctic sublitoral species. It was collected in the Scotia subregion of the Antarctic ( Daday 1908 ; Kornicker 1971 , 1975 ; Hartmann 1989 ), Prydz Bay and near the Russian Polar station “Molodezhnaya” (present study) between 63° and 69°S ( Fig. 23 ) at the depths of 4.5 to 1135 m , on hard and soft substrates: rock, stone, gravel, sand and muddy sand.