Philomedes cubitum Kornicker 1975

"HOLOTYPE—USNM 138656, adult female without eggs, length 1.40 mm. Valves and some appendages in alcohol, remaining appendages on slides.

TYPE-LOCALITY—Hero Cruise 69-5, station 48.

ETYMOLOGY—The specific name is derived from the Latin "cubitum" [= elbow] and refers to the right angle formed by the selvage in the posteroventral corner of each valve.

PARATYPES—USNM 138660, juvenile female, length 0.95 mm, height 0.65 mm; USNM 138662, N-l male; USNM 138663, 1 adult female; USNM 138665, 20 juveniles, all from same sample as holotype.

ADDITIONAL SPECIMENS—USNM 138669, 1 N-l male + 4 juveniles, all from Hero Cruise 69-5, station 50.

DIAGNOSIS—Posterior with ventral corner only slightly more angular than dorsal corner and with very slight flattening of posterior margin; selvage forming right angle in posteroventral part of each valve; length about 1.40 mm.

First antenna: 2nd joint with 3 bristles, 1 ventral, 1 dorsal, 1 lateral.

Second antenna: 1st endopodial joint with 6 bristles, 2nd with 2.

Mandible: Dorsal margin of basale with 3 bristles.

Seventh limb: Each limb with about 22 bristles; 4 pegs (1 longer than others) present opposite comb.

Furca: Each lamella with 5 stout claws followed by 5 weaker claws.

Lateral eye: Small with 2 ommatidia.

DESCRIPTION OF ADULT FEMALE—Carapace with prominent rostrum with anterior and inferior corners rounded and small protuberance at lower end; posterior margin with ventral corner only slightly more angular than dorsal corner and with very slight flattening of posterior edge, otherwise appearing evenly rounded.

Ornamentation: Carapace smooth but with minute pores visible under high magnification; short and long hairs scattered over surface, more abundant on rostrum and along anteroventral margin.

Infold: Infold broad along anterior, ventral, and posteroventral margin; infold on rostrum with about 21 bristles; 1 small bristle present on infold posterior to incisur; anteroventral part striate with about 9 short bristles; infold along ventral margin bare; ridge paralleling inner margin of posteroventral and posterior infold with about 25 bristles in groups of 1 to 3 bristles; selvage forming right angle on posteroventral infold of both valves (selvage farther from posterior edge on right valve); 1 or 2 small bristles present on posteroventral infold anterior to right angle of selvage; 1 or 2 bristles present on posterior corner of right angle of selvage on both valves.

Selvage: Selvage unusual in having right angle in posteroventral part of each valve. Lamellar prolongation fringed, broadly striate in area of rostrum and incisur; anteroventral prolongation striate and with long hairs on lateral side.

Size: USNM 138656, length 1.40 mm, height 1.02 mm; USNM 138663, length 1.39 mm, height 1.11 mm.

First antenna: 1st and 2nd joints with spines along dorsal and ventral margins and lateral and medial surfaces; 2nd joint with 3 spinous bristles, 1 ventral, 1 dorsal, 1 lateral; 3rd joint with 3 terminal bristles with short marginal spines, 1 ventral, 2 dorsal, and minute teeth forming row near middle of medial and lateral surfaces; 4th joint with 6 spinous bristles, 4 ventral, 2 dorsal; sensory bristle of 5th joint with 5 short proximal filaments and 3 longer terminal filaments not including stem; medial bristle of 6th joint with long proximal and short distal spines. Seventh joint: abristle spinous, slightly longer than bristle of 6^th joint; b-bristle with 1 proximal and 3 distal filaments excluding tip; c-bristle with 5 short proximal filaments and 4 terminal filaments excluding stem. Eighth joint: d- and e-bristles bare; f-bristle with 4 short proximal filaments and 4 terminal filaments excluding tip; g-bristle with 3 or 4 proximal filaments and 4 terminal filaments excluding tip; filaments on all bristles bare except for spine at tip.

Second antenna: Protopodite bare. Endopodite 2-jointed: 1st joint with 5 proximal and 1 distal bristle; 2nd joint with 1 long ventral bristle with wreaths of long spines and 1 long recurved terminal bristle. Exopodite: 1st joint with small distomedial spine; bristles of joints 6 to 8 with natatory hairs; bristles of joints 6 to 8 and 4 long bristles of 9th joint broken on holotype; middle of ventral margins of bristles of joints 2 to 5 with stout teeth; joints 2 to 8 with stout basal spine and short spines forming row; joint 9 with 7 bristles (4 long broken bristles with natatory hairs on remaining part, 3 short with short marginal spines).

Mandible: Coxale with spines forming groups on medial surface; coxale endite spinous with bifurcate tip and small bristle near base. Basale: dorsal margin with 3 bristles, 1 near middle with short faint marginal spines, 2 terminal (longer of these with long proximal spines, shorter bristle bare); medial surface with 6 short proximal bristles, 3 stout pectinate, 3 slender with long spines; ventral margin with 2 bristles with long proximal and short distal spines; lateral surface with 5 bristles oriented venteriad; medial and lateral surface of basale with spines forming clusters. Exopodite with hirsute tip reaching halfway up dorsal margin of 1st endopodite joint and with 2 bristles (inner longer bristle with long proximal and short distal spines, outer shorter bristle with short marginal spines or bare). Endopodite: ventral margin of 1st joint with 4 spinous bristles; dorsal margin with short spines forming row on distal corner; dorsal margin of 2nd joint with 3 bristles in proximal group and 5 in distal group; distal ventral margin with 3 spinous bristles in both proximal and distal groups; proximal medial surface of 2nd joint with long and short spines forming rows; end joint with 4 bristles and 3 stout claws with teeth along middle of ventral margin.

Maxilla: Endite I with 10 bristles, endite II with 7 bristles, endite III with 1 proximal and about 9 distal bristles. Coxale with stout plumose bristle. Exopodite short with 3 bristles: proximal bristle short with short marginal spines; 1 terminal bristle with short marginal spines, other with wreaths of long spines. Distal margin of basale with 3 long bristles. Endopodite: 1st joint with single a-bristle with wreaths of long spines and 4 6-bristles; end joint with 4 a-bristles, 3 clawlike pectinate bristles and several bare and spinous bristles.

Fifth limb: Epipodial appendage with 49 bristles. Exopodite 1st joint: triangular protuberance in front of main tooth with proximal node; main tooth with 3 pectinate teeth and short proximal tooth either smooth or with few teeth; 1 spinous bristle proximal to smooth tooth. Exopodite 2^nd joint: large triangular tooth with 2 nodes on medial margin; lateral corner with 2 short spinous bristles; posterior side with usual stout bristle and group of 3 bristles distal to it. Exopodite 3^rd joint: medial lobe with 3 spinous bristles, outer lobe with 2 spinous bristles. Fourth and 5th joints fused and with 6 spinous bristles.

Sixth limb: Epipodial appendage with 3 or 4 hirsute bristles; 1st endite with 2 spinous bristles, 1 medial short, 1 terminal longer; 2nd endite with 4 spinous bristles, 1 medial, 3 terminal; 3rd endite with 9 spinous bristles, 1 medial, 8 terminal; 4th endite with 9 spinous bristles, 1 medial, 8 terminal; end joint with 20 bristles (about 7 medial, remainder ventral or slightly lateral); medial and lateral surfaces of end joint and lateral surfaces of endites 1 to 4 hirsute; posterior end of end joint projecting posteriorly.

Seventh limb: Each limb with 22 bristles, 5 in distal group (3 dorsal, 2 ventral) and 17 proximal (10 dorsal, 7 ventral); each bristle with 3 to 7 bells and distal marginal spines; end comb with 11 alate teeth with 2 basal teeth on each side; 4 short pegs (1 of these longer than others) on dorsal side opposite comb.

Furca: Each lamella with 5 stout claws followed by 5 weaker claws; claw 1 with stout teeth along concave margin and along medial surface; tips of main claws rounded; hairs present at bases of claws and following last claw.

Eyes and rod-shaped organ: Lateral eye minute with 2 small ommatidia; medial eye large, bare, pigmented; rod-shaped organ elongate, 2 jointed, with rounded tip.

Upper lip: Lip hirsute; single elongate process present between lip and medial eye.

Posterior: Posterior margin hirsute above furca and in posterodorsal area.

Parasites: USNM 138656 with cuplike stalked protistans attached to many appendages.

Gut content: Gut of USNM 138656 with polychaete spines, probably of family Syllidae according to M. Pettibone (pers. comm., 1971).

DESCRIPTION OF N-l MALE—Carapace similar in shape to adult female, except posterior slightly truncate. Size: USNM 138662, length 1.23 mm, height 0.93 mm; USNM 138669, length 1.24 mm, height 0.84.

Second antenna: Endopodite 3-jointed: 1st joint with 4 bristles; 2nd joint elongate with 3 ventral bristles; 3rd joint elongate with 1 long proximal bristle and 2 short terminal bristles.

Seventh limb: Well developed.

Lateral eye: Small with 2 minute ommatidia; diameter of eye about twice that of lateral eye on adult female.

Medial eye and rod-shaped organ: Similar to those on adult female.

COMPARISON—This new species, P. cubitum, is only slightly larger than P. minys and the appendages of both species are very similar. The posterior margin of the carapace of the adult female of P. minys, however, is distinctly truncate, and its posterior selvage does not have the rightangled bend present in the selvage of P. cubitum. Juveniles of P. cubitum, having a slightly truncate posterior, resemble the carapace of P. minys, but P. cubitum can be identified by the right-angled bend in the posterior selvage. The right-angled bend of the selvage on the posteroventral corner of the carapace of P. cubitum has not been reported in other species of Philomedes.

DISTRIBUTION—This species was collected only at two stations in the Magellanic subregion of the Subantarctic region at depths of 21 to 28 m." (Kornicker 1975, p.289-293)

Philomedes cubitum

HOLOTYPE.—USNM 138656, adult ♀ without eggs, length 1.40 mm. Valves and some appendages in alcohol, remaining appendages on slides.

TYPE-LOCALITY.—Hero Cruise 69–5, station 48.

ETYMOLOGY.—The specific name is derived from the Latin “cubitum” [= elbow] and refers to the right angle formed by the selvage in the posteroventral corner of each valve.

PARATYPES.—USNM 138660, juvenile ♀, length 0.95 mm, height 0.65 mm; USNM 138662, N–1 ♂; USNM 138663, 1 adult ♀; USNM 138665, 20 juveniles, all from same sample as holotype.

ADDITIONAL SPECIMENS.—USNM 138669, 1 N–1 ♂ + 4 juveniles, all from Hero Cruise 69–5, station 50.

DIAGNOSIS.—Posterior with ventral corner only slightly more angular than dorsal corner and with very slight flattening of posterior margin; selvage forming right angle in posteroventral part of each valve; length about 1.40 mm.

First antenna: 2nd joint with 3 bristles, 1 ventral, 1 dorsal, 1 lateral.

Second antenna: 1st endopodial joint with 6 bristles, 2nd with 2.

Mandible: Dorsal margin of basale with 3 bristles.

Seventh limb: Each limb with about 22 bristles; 4 pegs (1 longer than others) present opposite comb.

Furca: Each lamella with 5 stout claws followed by 5 weaker claws.

Lateral eye: Small with 2 ommatidia.

DESCRIPTION OF ADULT FEMALE. (Figures 178, 179a-k).—Carapace with prominent rostrum with anterior and inferior corners rounded and small protuberance at lower end; posterior margin with ventral corner only slightly more angular than dorsal corner and with very slight flattening of posterior edge, otherwise appearing evenly rounded (Figures 178, 179a-d).

Ornamentation: Carapace smooth but with minute pores visible under high magnification; short and long hairs scattered over surface, more abundant on rostrum and along anteroventral margin.

Infold (Figure 179b-d): Infold broad along anterior, ventral, and posteroventral margin; infold on rostrum with about 21 bristles; 1 small bristle present on infold posterior to incisur; anteroventral part striate with about 9 short bristles; infold along ventral margin bare; ridge paralleling inner margin of posteroventral and posterior infold with about 25 bristles in groups of 1 to 3 bristles; selvage forming right angle on posteroventral infold of both valves (selvage farther from posterior edge on right valve); 1 or 2 small bristles present on posteroventral infold anterior to right angle of selvage; 1 or 2 bristles present on posterior corner of right angle of selvage on both valves.

Selvage: Selvage unusual in having right angle in posteroventral part of each valve. Lamellar prolongation fringed, broadly striate in area of rostrum and incisur; anteroventral prolongation striate and with long hairs on lateral side.

Size (Figure 131); USNM 138656, length 1.40 mm, height 1.02 mm; USNM 138663, length 1.39 mm, height 1.11 mm.

First antenna: 1st and 2nd joints with spines along dorsal and ventral margins and lateral and medial surfaces; 2nd joint with 3 spinous bristles, 1 ventral, 1 dorsal, 1 lateral; 3rd joint with 3 terminal bristles with short marginal spines, 1 ventral, 2 dorsal, and minute teeth forming row near middle of medial and lateral surfaces; 4th joint with 6 spinous bristles, 4 ventral, 2 dorsal; sensory bristle of 5th joint with 5 short proximal filaments and 3 longer terminal filaments not including stem; medial bristle of 6th joint with long proximal and short distal spines. Seventh joint: a-bristle spinous, slightly longer than bristle of 6th joint; b-bristle with 1 proximal and 3 distal filaments excluding tip; c-bristle with 5 short proximal filaments and 4 terminal filaments excluding stem. Eighth joint: d- and e-bristles bare; f-bristle with 4 short proximal filaments and 4 terminal filaments excluding tip; g-bristle with 3 or 4 proximal filaments and 4 terminal filaments excluding tip; filaments on all bristles bare except for spine at tip.

Second antenna (Figure 179e): Protopodite bare. Endopodite 2-jointed: 1st joint with 5 proximal and 1 distal bristle; 2nd joint with 1 long ventral bristle with wreaths of long spines and 1 long recurved terminal bristle. Exopodite: 1st joint with small distomedial spine; bristles of joints 6 to 8 with natatory hairs; bristles of joints 6 to 8 and 4 long bristles of 9th joint broken on holotype; middle of ventral margins of bristles of joints 2 to 5 with stout teeth; joints 2 to 8 with stout basal spine and short spines forming row; joint 9 with 7 bristles (4 long broken bristles with natatory hairs on remaining part, 3 short with short marginal spines).

Mandible (Figure 179f): Coxale with spines forming groups on medial surface; coxale endite spinous with bifurcate tip and small bristle near base. Basale: dorsal margin with 3 bristles, 1 near middle with short faint marginal spines, 2 terminal (longer of these with long proximal spines, shorter bristle bare); medial surface with 6 short proximal bristles, 3 stout pectinate, 3 slender with long spines; ventral margin with 2 bristles with long proximal and short distal spines; lateral surface with 5 bristles oriented venteriad; medial and lateral surface of basale with spines forming clusters. Exopodite with hirsute tip reaching halfway up dorsal margin of 1st endopodite joint and with 2 bristles (inner longer bristle with long proximal and short distal spines, outer shorter bristle with short marginal spines or bare). Endopodite: ventral margin of 1st joint with 4 spinous bristles; dorsal margin with short spines forming row on distal corner; dorsal margin of 2nd joint with 3 bristles in proximal group and 5 in distal group; distal ventral margin with 3 spinous bristles in both proximal and distal groups; proximal medial surface of 2nd joint with long and short spines forming rows; end joint with 4 bristles and 3 stout claws with teeth along middle of ventral margin.

Maxilla: Endite I with 10 bristles, endite II with 7 bristles, endite III with 1 proximal and about 9 distal bristles. Coxale with stout plumose bristle. Exopodite short with 3 bristles: proximal bristle short with short marginal spines; 1 terminal bristle with short marginal spines, other with wreaths of long spines. Distal margin of basale with 3 long bristles. Endopodite: 1st joint with single α-bristle with wreaths of long spines and 4 β-bristles; end joint with 4 a-bristles, 3 clawlike pectinate bristles and several bare and spinous bristles.

Fifth limb: Epipodial appendage with 49 bristles. Exopodite 1st joint: triangular protuberance in front of main tooth with proximal node; main tooth with 3 pectinate teeth and short proximal tooth either smooth or with few teeth; 1 spinous bristle proximal to smooth tooth. Exopodite 2nd joint: large triangular tooth with 2 nodes on medial margin; lateral corner with 2 short spinous bristles; posterior side with usual stout bristle and group of 3 bristles distal to it. Exopodite 3rd joint: medial lobe with 3 spinous bristles, outer lobe with 2 spinous bristles. Fourth and 5th joints fused and with 6 spinous bristles.

Sixth limb (Figure 179g): Epipodial appendage with 3 or 4 hirsute bristles; 1st endite with 2 spinous bristles, 1 medial short, 1 terminal longer; 2nd endite with 4 spinous bristles, 1 medial, 3 terminal; 3rd endite with 9 spinous bristles, 1 medial, 8 terminal; 4th endite with 9 spinous bristles, 1 medial, 8 terminal; end joint with 20 bristles (about 7 medial, remainder ventral or slightly lateral); medial and lateral surfaces of end joint and lateral surfaces of endites 1 to 4 hirsute; posterior end of end joint projecting posteriorly.

Seventh limb (Figure 179h): Each limb with 22 bristles, 5 in distal group (3 dorsal, 2 ventral) and 17 proximal (10 dorsal, 7 ventral); each bristle with 3 to 7 bells and distal marginal spines; end comb with 11 alate teeth with 2 basal teeth on each side; 4 short pegs (1 of these longer than others) on dorsal side opposite comb.

Furca (Figure 179i): Each lamella with 5 stout claws followed by 5 weaker claws; claw 1 with stout teeth along concave margin and along medial surface; tips of main claws rounded; hairs present at bases of claws and following last claw.

Eyes and rod-shaped organ (Figure 179j): Lateral eye minute with 2 small ommatidia; medial eye large, bare, pigmented; rod-shaped organ elongate, 2 jointed, with rounded tip.

Upper lip (Figure 179j): Lip hirsute; single elongate process present between lip and medial eye.

Posterior: Posterior margin hirsute above furca and in posterodorsal area.

Parasites: USNM 138656 with cuplike stalked protistans attached to many appendages.

Gut content: Gut of USNM 138656 with polychaete spines, probably of family Syllidae according to M. Pettibone (pers. comm., 1971).

DESCRIPTION OF N–1 MALE (Figure 179l,m).—Carapace similar in shape to adult female, except posterior slightly truncate. Size: USNM 138662, length 1.23 mm, height 0.93 mm; USNM 138669, length 1.24 mm, height 0.84.

Second antenna (Figure 179l): Endopodite 3-jointed: 1st joint with 4 bristles; 2nd joint elongate with 3 ventral bristles; 3rd joint elongate with 1 long proximal bristle and 2 short terminal bristles.

Seventh limb: Well developed.

Lateral eye (Figure 179m): Small with 2 minute ommatidia; diameter of eye about twice that of lateral eye on adult female.

Medial eye and rod-shaped organ (Figure 179m): Similar to those on adult female.

COMPARISON.—This new species, P. cubitum, is only slightly larger than P. minys and the appendages of both species are very similar. The posterior margin of the carapace of the adult female of P. minys, however, is distinctly truncate, and its posterior selvage does not have the right-angled bend present in the selvage of P. cubitum. Juveniles of P. cubitum, having a slightly truncate posterior, resemble the carapace of P. minys, but P. cubitum can be identified by the right-angled bend in the posterior selvage. The right-angled bend of the selvage on the posteroventral corner of the carapace of P. cubitum has not been reported in other species of Philomedes.

DISTRIBUTION.—This species was collected only at two stations in the Magellanic subregion of the Subantarctic region at depths of 21 to 28 m (Figure 132).

Philomedes Species Indeterminate

MATERIAL.—USNM 125850, 1 juvenile ♂, length 1.64 mm, height 1.28 mm; USNM 125851, 1 juvenile, length 1.05 mm, height 0.73 mm; USNM 125852, 1 juvenile; USNM 125864, 1 juvenile, length 1.13 mm, height 0.71 mm; USNM 125865, 1 juvenile, length 1.26 mm, height 0.10 mm; USNM 127252, 1 juvenile ♂, length 1.45 mm, height 1.11 mm; USNM 127253, 1 juvenile; USNM 127498, 3 juveniles; USNM 136178, 1 adult ♂, length 2.27 mm, height 1.28 mm; Discovery Cruise 1, station 61 (residue 92), 1 juvenile; USNM 138153, 1 juvenile, length 2.72 mm, height 1.95 mm; USNM 138155, 1 juvenile, length 1.50 mm, height 1.02 mm; USNM 138658, 235 juveniles; USNM 138666, 1 juvenile, length 1.01 mm, height 0.68 mm, + 8 juveniles; USNM 139100, 1 juvenile; USNM 139146, 1 juvenile; USNM 125495, 1 juvenile.

USNM 125850–125852 from Deep Freeze II, Glacier station 19; USNM 125864 from Deep Freeze III, Glacier station Bl-8j; USNM 125865 from Deep Freeze II, Glacier station 22; USNM 127252 from IWSOE, Glacier Cruise 2, station 0010; USNM 127253 from IWSOE, Glacier 2, station 0006; USNM 127498 from Deep Freeze I, Edisto stations 5, 6, 8 combined; USNM 136178 from Octans station AM; USNM 138153 from Vema Cruise 14, station V–14–32; USNM 138155 from Deep Freeze IV, Staten Island station S.I.4; USNM 138658 from Hero Cruise 69–5, station 48; USNM 138666 from Hero Cruise 69–5, station 49; USNM 139100 from Hero Cruise 69–5, station 53; USNM 139146 from Hero Cruise 71–2, station 665; USNM 125495 from Staten Island station 37/63.

DISTRIBUTION.—The distribution of Philomedes species indeterminate is shown in Figure 135.

Euphilomedes Poulsen, 1962

TYPE-SPECIES.—Euphilomedes nodosa Poulsen, 1962, by subsequent designation (Kornicker, 1967a).

This genus is represented by two species in the study area: E. agilis (Thomson, 1879) and E. ferox Poulsen, 1962. Both species belong in the agilis-group of Poulsen (1962:361).

DIAGNOSIS OF agilis-GROUP.—Carapace without ornamentation other than punctae, with shallow incisur, and without caudal process.

Second antenna: Endopodite of male 3-jointed, reflexed. Endopodite of female (N–1 stage) known only for E. ferox: 2-jointed with small 2nd joint bearing 2 bristles. Exopodite: 9th joint with 4 to 6 bristles.

Mandible: Dorsal margin of 2nd endopodite of mandible with bristles forming 3 groups. End joint with not more than 2 claws.

Rod-shaped organ: Organ unsegmented, broadening in middle and tapering distally.

Furca: Claws 1, 2, and 4 primary; claw 3 and claws posterior to claw 4 secondary.

DISTRIBUTION.—The genus Euphilomedes is widely distributed. Its northern limit is about 63°N. The northern limit of members of the agilis-group is about 20°N. The genus is represented in the study area only in the vicinity of Australia and New Zealand, the southernmost limit of the range is 45°50′S (Figure 127). Members of the genus have been mostly collected in shallow water. Males are often collected in surface plankton tows. In the present study area the depth range is intertidal to about 100 m.

BENTHIC