Philomedes reticulata Hartmann 1965

Philomedes (Scleroconcha) reticulata Hartmann, 1965:311, figs. 8–11

HOLOTYPE.—According to Hartmann (1965:311) “Holotypus zergliedert.”

TYPE-LOCALITY.—Station 108, 40°53.5′S, 73°58.5′W, 136 m, by Cabo Quedal, Chile (from Hartmann, 1965:312).

MATERIAL.—Through Dr. Gerd Hartmann, I received from the Hamburg Zoological Museum two vials, K 27 284, K 27 281. Both numbers are listed as paratypes by Hartmann.

Vial number K 27 284 contained 1 specimen without carapace, 1 specimen without carapace and furca, 1 pair of articulated valves without animal, 2 disarticulated left and 2 disarticulated right valves, 1 complete adult female without eggs, 3 smaller complete specimens, several appendages (2 furcae, 1 exopodite of 2nd antenna, 1 7th limb), and several loose eggs. Vial number K 27 281 contained 3 complete males, 4 disarticulated valves of males and many male appendages.

In the present study one of the females without a carapace in vial K 27 284 was dissected and mounted. Most of the figures and the description of appendages are based on that specimen. As the specimen did not have a furca, this was drawn from a different specimen. The description and figures of the carapace are based on the disarticulated valves. The description and figures of the male are based on both loose appendages in vial K 27 281 and on a complete specimen which I partly dissected.

Hartmann (1965:315) reported 4 females from station 96, 2 females from station 106, 3 females and 1 male from station 108.

NEW COLLECTIONS.—USNM 137681, 1 gravid ♀ with 9 eggs, length 1.84 mm, height 1.23 mm, + 1 juvenile ♂, both from Eltanin Cruise 21, station 194.

DIAGNOSIS OF FEMALE.—Carapace surface with large reticulations and 3 horizontal ribs, 1 above central muscle attachment area, 1 just below area, and 1 just within ventral margin of valve; carapace length 1.67 to 1.84 mm.

Mandible: Dorsal margin of basale with 3 bristles, 1 distal to middle, 2 terminal.

Seventh limb: Each limb with 10 bristles, 4 proximal, 6 distal.

Furca: Each lamella with 12 or 13 claws, 4 long claws followed by 8 or 9 short claws.

Rod-shaped organ: Tip pointed.

SUPPLEMENTARY DESCRIPTION OF FEMALE (Figures 215–219).—Surface with large reticulations (Figure 217b, also Hartmann, 1965:312, fig. 8) and scattered surface hairs; each valve with 3 faint horizontal ribs, 1 above the central muscle scar area, 1 just below the scar area, and 1 just within the ventral margin of shell; triangular process on rostrum just reaching to or slightly beyond edge of shell; small swelling present on posteroventral part of shell (Figures 215a-d, 217).

Infold (Figure 215b,c): Infold on rostrum with 9 bristles, some with spines; small bristle present below inner end of broad incisur followed by space and then about 7 short spinous bristles forming row on anteroventral infold; ventral infold bare; posteroventral and posterior list with numerous bristles in groups of 1 to 4 or 5 bristles; ridge with only 1 bristle present between posterior list and outer edge of valve; 1 bristle present near valve edge between ridge and posterior valve margin.

Selvage: Striate lamellar prolongation with short fringe discontinuous in area of incisur.

Size (Figure 220): Complete specimen, length 1.77 mm, height 1.14 mm; disarticulated left valve, length 1.73 mm, height 1.04 mm; disarticulated right valve, length 1.71 mm, height 1.07 mm; disarticulated left valve 1.68 mm, height 1.06 mm; disarticulated right valve, length 1.67 mm, height 1.02 mm. USNM 137681, length 1.84 mm, height 1.23 mm.

First antenna: 1st joint with short spines forming clusters on lateral surface near dorsal margin and long hairs on medial surface; 2nd joint spinous and with 3 bristles, 1 ventral, 1 dorsal, 1 lateral, all with long proximal and short distal spines; 3rd joint with few spines and with 3 bristles, 1 ventral with short marginal spines, 2 dorsal (1 with short marginal spines, 1 with few long proximal spines plus short distal spines); 4th joint with spines along ventral and dorsal margins and 5 spinous bristles, 4 ventral, 1 dorsal; spines forming row present along distal lateral margin of 5th joint; sensory bristle of 5th joint with 6 proximal and 5 distal filaments; medial bristle of 6th joint with long proximal and short distal spines. Seventh joint: a-bristle similar to bristle on 6th joint but slightly longer; b-bristle with 4 proximal and 4 distal filaments including tip; c-bristle with 6 proximal and 5 distal filaments including tip. Eighth joint: d- and e-bristles long bare; f-bristle with 4 proximal and 4 distal filaments including stem; g-bristle with about 2 proximal and 4 distal bristles.

Second antenna (Figure 215e): Protopodite bare. Endopodite 3-jointed: 1st joint with 6 bare bristles, 5 proximal, 1 distal; 2nd joint with 1 long stout spinous ventral bristle and 1 bare terminal bristle. Exopodite: distal margins of joints 2 to 8 with short and long spines forming row; 1st joint with 1 small medial spine on terminal margin; several minute basal spines present at base of bristles on joints 2–4; single basal spine present on joints 5–8; 9th joint with 7 bristles; bristle of 2nd joint with short spines along middle part of ventral margin; bristles on joints 2 and 3 bare, remaining bristles with natatory hairs.

Mandible (Figure 215f): Coxale endite with small bristle at base; bifurcate tip of endite with small rounded teeth laterally. Basale: medial surface spinous and with 5 bristles near ventral margin, 4 proximal, 1 near middle (2 or 3 proximal bristles pectinate); lateral surface with 5 spinous bristles near ventral marein: ventral margin with 2 distal bristles; dorsal margin with 3 bristles, 1 distal to middle, 2 terminal, all with long proximal and short distal spines. Exopodite about 70 percent length of dorsal margin of 1st endopodite joint, hirsute near tip and with 2 bristles, both with long proximal and short distal spines. Endopodite: 1st joint with spines forming clusters on medial surface and 4 ventral bristles, all with long proximal and short distal spines; medial surface and margins of 2nd joint with spines forming clusters; ventral margin with bristles forming 2 distal groups, of these, proximal group with 2 bristles (1 with short marginal spines, 1 with long proximal and short distal spines) and distal group with 3 bristles with short marginal spines; dorsal margin with bristles forming 2 groups proximal to middle of margin (bristles missing in proximal group), 6 bristles in distal group; 1 short pectinate bristle present on medial side of joint between the 2 groups of bristles; end joint with 3 claws and about 3 bristles, all claws with teeth along middle part of concave margin (dorsal claw shorter than others, reaching middle of longest claw).

Maxilla (Figure 216a): 1st endite with 7 distal bristles; 2nd endite with 6 distal bristles; 3rd endite with 8 distal bristles and long proximal hairs; coxale with 1 stout plumose bristle (in Figure 216a coxale and basale twisted so that plumose bristle appears ventral); basale with 1 short proximal bristle with few short marginal spines near proximal end of 3rd endite; distal margin of basale with 1 short anterior bristle and 1 long spinous posterior bristle (3rd bristle usually present not observed, but possibly obscure). Exopodite small with 3 bristles: proximal bristle short with long proximal and short distal spines; middle terminal bristle long with long proximal and short terminal spines; inner terminal bristle long with short marginal spines. Endopodite: 1st joint with 1 α-bristle with long proximal and short distal spines and 3 β-bristles; end joint with 3 a-bristles; 1 of the band 2 of the d-bristles clawlike, pectinate.

Fifth limb (Figure 216b-d): Epipodial appendage with 51 bristles; endite I with 5 spinous bristles; endite II with 7 or 8 spinous bristles; endite III with 9 or 10 spinous bristles. Exopodite: anterior side of 1st joint with 2 spinous bristles near middle of distal margin; 1 short spinous bristle present on lobe near outer side of 1st joint (position of base of lobe not clear but seems to be from same joint as 1st endite); main tooth of 1st joint consisting of 4 teeth, all pectinate; 1 spinous bristle present proximal to teeth of main tooth; triangular protuberance almost as long as distal tooth of main tooth and with 2nd smaller triangular protuberance on proximal margin; anterior side of 2nd joint with small d-bristle on anterior projection near outer corner of large quadrate tooth; posterior side with total of 3 a- and b-bristles and 1 long spinous c-bristle; margin of inner curvature of large tooth of 2nd joint with 1 small pointed node and 2 undulations proximal to it; outer lobe of 3rd joint with 2 hirsute bristles, proximal bristle about half length of other; inner lobe with 3 spinous and pectinate bristles; fused 4th and 5th joints hirsute and with about 5 spinous bristles.

Sixth limb (Figure 216e): 3 hirsute bristles present in place of epipodial appendage; endite I with 1 stout spinous terminal bristle; endite II with 3 spinous terminal bristles; endite III with 8 bristles, 1 medial, 7 terminal; endite IV with 7 spinous bristles, 1 medial, 6 terminal; end joint prolonged posteriorly and with 20 to 25 spinous and hirsute bristles; endites II–IV and end joint with clusters of long hairs on medial and lateral surfaces. (Endites observed only on right limb, endites of left limb fragmented; presence of only 1 bristle on endite I needs verification on additional specimens.)

Seventh limb (Figures 215j, 216f): Each limb with 10 bristles, 4 proximal (2 on each side) and 6 distal (3 on each side); each bristle with 3 to 6 bells and distal marginal spines; terminal comb with 14 alate teeth; tip of jaw opposite comb bare.

Furca (Figure 216g): Each lamella with 12 or 13 claws; claw 3 slightly longer and narrower than claw 4; claw 5 about two-thirds length of claw 4; claws arranged in 2 groups consisting of long claws (claws 1 to 4) and short claws (claws 5 to 12 or 13); each claw with marginal teeth along concave margin and hairs near base.

Rod-shaped organ (Figures 216h, 218): Elongate with 2 or 3 distinct sutures near middle; distal half of organ with minute surface hairs and spines; tip drawn out to fine point and with several small hairs.

Eyes (Figures 215g,i; 216h): Lateral eye elongate with 2 or 3 small ommatidia; medial eye pigmented.

Upper lip (Figures 216i, 219): Lip hirsute with anterior projection without spines; rounded single process present between upper lip and medial eye.

Posterior: Short spines along dorsal part.

Eggs: USNM 137681 with 9 eggs in marsupium.

Epizoa: 1 small organism present on posterior margin of 1 valve of K 27 284 (Figure 215k).

SUPPLEMENTARY DESCRIPTION OF ADULT MALE (Figure 221).—Carapace slightly longer than that of female; reticulations smaller than those on female and without horizontal ridges; hairs scattered on valve surface; broad lamellar prolongation of selvage similar to that on female (Figure 221a,b). Size: length 1.88 mm, height 0.96 mm (Figure 220).

Second antenna: Endopodite 3-jointed: 1st joint short with 6 short bristles, 5 proximal, 1 distal; 2nd joint elongate with 3 spinous ventral bristles; 3rd joint reflexed with 1 proximal and 2 subterminal bristles and with numerous small pustules on surface (Figure 221c).

Seventh limb: Each limb with 8 to 10 bristles, 4 to 6 proximal (2 or 3 on each side), 4 distal (2 on each side); terminal comb with 10 alate teeth; no peg observed on jaw opposite comb (Figure 221d).

Furca: Each limb with 10 or 11 claws; claw 3 shorter and more slender than claw 4; claw 5 to 10 or 11 much shorter than claws 1 to 4 (Figure 221e).

Rod-shaped organ (Figure 221 f): Elongate with pointed tip; 1 suture present near middle; small surface spines present on distal half of organ.

Eyes: Medial eye pigmented (Figure 221f); lateral eye well developed, larger than medial eye, with about 20 ommatidia (Figure 221g).

Epizoa: 1 small organism present on 1 valve beneath incisur.

DISTRIBUTION.—This species was collected only in the Subantarctic-to-35°S region west of Chile (33°03′S to 40°53′S) at depths of 139 to 260 m (Figure 222).