Philomedes charcoti Daday 1908

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.