Philomedes albatross Kornicker 1982

Philomedes albatross

Philomedes globosus.—Hulings, 1967:311 [part].

Etymology.—The specific name from the vessel from which the holotype was collected, the R/V Albatross.

HOLOTYPE.—USNM 158030, 1 adult female with large unextruded eggs, in alcohol and on slides.

TYPE-LOCALITY.—R/V Albatross sta 2490, 6 July 1885, off Nova Scotia, 45°27′30″N, 58°27′45″W, water depth 91.4 m, collected in dredge.

PARATYPES.—R/V Vema: USNM 157949, 1 ovigerous female; USNM 157950, 18 specimens, sta V-16-58. USNM 157943A, B, 2 A-1 males; USNM 157943C, 5 early instars, sta V-16-59. USNM 157944, 157945, 157948, 2 ovigerous females, and 1 adult female; USNM 157946, 110 specimens, sta V-16-63. USNM 157942A, C, 2 ovigerous females; USNM 157942B, 1 juvenile; USNM 119445-446, 1 ovigerous female, collected by A.S. Packard off Hopedale, Labrador.

DISTRIBUTION.—Northwest Atlantic Ocean off Labrador, New Foundland, Cape Breton Island, and Nova Scotia. Latitudinal range 45°27′30″N-55°26′N; longitudinal range 57°23′W-59°W. Depth range 18-448 m.

DESCRIPTION OF ADULT FEMALE (Figures 5–9).—Carapace ovoid in lateral view, with narrow caudal process, without dentition along margin, with broad rostrum with convex anterior margin and deep incisur; posterior end in lateral view somewhat truncate dorsal to middle (Figures 5, 6a–e, 7a).

Ornamentation (Figures 6, 7f): Surface with numerous short bristles (Figures 6f, 7f), and sparsely distributed longer bristles with broad, ribbed, bases (Figure 6f); long bristles, some without broad base, more abundant along ventral and anterior margins; ventral tip of rostrum with minute process barely extending past valve edge.

Infold (Figure 7c–e): Rostral infold with about 17 bristles (Figure 7c); anteroventral infold with small bristle near inner end of incisur followed by space without bristles, and then 17 spinous bristles forming row; 9 parallel ridges present on anteroventral infold; 2nd ridge from valve margin continuing on ventral and posterior infold as list; infold along middle of ventral margin without bristles; posteroventral and posterior infold with about 52 short slender bristles forming groups (1–4 bristles per group) along distal edge of list; infold of narrow caudal process with 9 bristles between list and valve margin (Figure 7d), but without “pocket.”

Selvage: Broad lamella prolongation present along free margins but narrower along posteroventral and posterior margins than along anterior and anteroventral margins; outer edge of prolongation with marginal fringe of long hairs except along ventral margin anterior to caudal process; long lateral hairs with bases near proximal edge of prolongation present on selvage just ventral to incisur (Figure 7e).

Size: USNM 158030, length 2.49 mm, height 1.75 mm; USNM 119445-446, length 2.47 mm, height 1.79 mm; USNM 157949, length 2.56 mm, height 1.81 mm; USNM 157942A, length 2.35 mm, height 1.60 mm; USNM 157944, length 2.27 mm, height 1.56 mm; USNM 157945, length 2.26 mm, height 1.69 mm; USNM 157942C, length 2.32 mm, height 1.63 mm; USNM 157948, length 2.24 mm, height 1.64 mm.

First Antenna (Figure 8a): 1st joint with medial and lateral hairs and spines. 2nd joint with medial and lateral hairs and spines and 3 spinous bristles (1 ventral, 1 dorsal, 1 lateral). 3rd joint short, with few, short, lateral spines forming rows, and 3 spinous bristles (1 ventral, 2 dorsal). 4th joint with 5 bristles (4 ventral, 1 dorsal). Sensory bristle of 5th joint with 5 short marginal filaments and 5 short terminal filaments. 6th joint minute, with medial bristle bearing long proximal and short distal spines. 7th joint: a-bristle longer than bristle of 6th joint, with long proximal and short distal spines; b-bristle shorter than sensory bristle of 5th joint, with 1 short filament near middle and 4 short terminal filaments; c-bristle almost as long as bristle of 5th joint, with 5 short marginal filaments and 5 short terminal filaments. 8th joint: d- and e-bristles about same length as c-bristle, bare with blunt tips; f- and g-bristles about same length as c-bristle; f-bristle with 4 short marginal filaments and 5 short terminal filaments; g-bristle with 3 short marginal filaments and 5 short terminal filaments.

Second Antenna (Figure 8b): Protopodite bare. Endopodite 2-jointed: short 1st joint with 6 short bristles; elongate 2nd joint with 1 long ventral bristle and 1 recurved terminal bristle. Exopodite: elongate 1st joint with minute, straight, medial, spinelike, terminal bristle; bristles of joints 2–5 short, bare; bristles of joints 6–8 broken off proximal to natatory hairs; 9th joint with 7 bristles (4 long broken; 1 medium broken, 2 short with hairs or spines); joints 3–8 with small basal spine (longer on distal joints; spine of 8th joint about three-fourths length of 9th joint); joints 2–8 with small spines forming distal row.

Mandible (Figure 8c): Coxale endite bifurcate, hirsute, pectinate, with small bristle at base. Basale: dorsal margin with 4 spinous bristles (2 distal to middle, 2 terminal); medial side spinous, with 3 pectinate, unringed bristles and 2 short, ringed bristles, all in proximal ventral corner, and 1 ringed bristle near middle; ventral margin with 3 long, spinous, distal bristles; lateral side with 5 spinous bristles (proximal 2 of these with bases almost on ventral margin). Exopodite hirsute, almost reaching distal margin of 1st endopodial joint, with 2 spinous subterminal bristles. 1st endopodial joint: dorsal margin with spines forming terminal row; ventral margin with 5 spinous bristles. 2nd endopodial joint: ventral margin with bristles forming 2 distal groups (3 bristles in each group); dorsal margin with about 11 bristles near middle (some with bases on medial and lateral sides); medial surface with spines forming rows near dorsal margin. End joint with 3 claws and 4 bristles.

Maxilla (Figure 8d,e): Endite I with 8 spinous and pectinate bristles; endite II narrow, with about 6 bristles; endite III elongate, with about 10 bristles. Precoxale and coxale with dorsal fringe of long hairs; coxale with hirsute dorsal bristle. Basale with 3 bristles on distal margin (1 dorsal, 2 ventral). Exopodite small, with 3 bristles (2 long, 1 short; inner long bristle and outer short bristle with long proximal hairs and short distal spines, other with short spines). 1st endopodial joint hirsute, with 1 spinous alpha-bristle and 5 beta-bristles. End joint with 3 stout, unringed, pectinate, clawlike bristles, and 10 ringed bristles.

Fifth Limb (Figure 9a-c): Epipodial appendage with 55 bristles. Endite I with 6 bristles; endite II with about 7 bristles; endite III with 8 or more bristles. 1st exopodial joint: main tooth consisting of 4 pectinate teeth; distal tooth with stout triangular anterior part (Figure 9c); spinous bristle with base just proximal to proximal tooth; anterior side of joint with 2 bristles near middle of distal margin, and 1 shorter spinous bristle near outer corner. 2nd exopodial joint: inner margin of large triangular tooth with 2 small teeth with uneven surface (the proximal of these much smaller than other) (Figure 9b); posterior side of joint with usual 4 bristles. 3rd endopodial joint with 2 bristles on outer lobe and 3 bristles on inner lobe. 4th plus 5th joint with total of 6 bristles (illustrated left limb of USNM 158031 with suture at base of 2 bristles).

Sixth Limb (Figure 9d): 3 or 4 bristles in place of epipodial appendage (distal of these longer than others). Endite I with 3 bristles; endite II with 1 proximal and 3 terminal bristles; endite III with 1 proximal and 9 terminal bristles; endite IV with 1 proximal and 7 terminal bristles. End joint with 21–24 bristles; limb hirsute.

Seventh Limb: Each limb with 29–30 bristles; comb or dorsal side with 13–14 bristles (4 of these on terminal segment); peg or ventral side with 15–17 bristles (4 or 5 of these on terminal segment); each bristle with up to 6 bells and marginal spines (spines forming 2–3 clusters on distal half of bristle). Terminal comb consisting of 10–15 teeth (middle tooth longer than others) (Figure 9e,f); 5–7 elongate pegs present opposite comb (1 of these longer than others, but none appearing more strongly sclerotized than others) (Figures 9e,f).

Furca (Figure 8f): USNM 158030 with 10 claws on right lamella, 11 on left lamella; claws decreasing in size posteriorly along lamella but claws 1–5 may be considered primary claws and claws 6–10 or 11 secondary claws; primary claws with long hairs forming medial row near base of bristle; all claws with teeth along posterior margin; claw 1 with lateral and medial row of teeth; distal 2 or 3 teeth of medial row much larger than others; faint hairs present on lamella following claws; anterior margin of lamella with few faint spines.

Bellonci Organ (Figure 9g): Elongate cylindrical, with suture near middle and rounded or pointed tip (see “Variability,” below).

Eyes: Medial eye with light amber pigment, bare. (Figure 9g). Lateral eye elongate, lightly pigmented, with scattered amber cells or 5 minute ommatidia (Figures 7b, 9g).

Upper Lip (Figure 9g): Projecting anteriorly, hirsute, with few processes at tip.

Anterior of Body (Figure 9g): Elongate process present between upper lip and medial eye.

Posterior of Body (Figure 8f): With few hairs.

Eggs: USNM 157949, 157942C, 157944, each with 12 eggs in marsupium; USNM 157942A with 15 eggs.

VARIABILITY.—Considerable variability was observed in the tip of the Bellonci organ: USNM 158030 with rounded tip; USNM 157948 with pointed, drawn-out tip; USNM 157945 with narrowly rounded tip bearing 2 spines; USNM 157944 with rounded tip bearing several minute spines. The number of comb teeth of the 7th limb of the adult female varies from 10 to 15, and the number of pegs opposite the comb from 5 to 7. The lateral eye of USNM 158030 contains minute amber cells; the cells are better developed in the lateral eye of USNM 157944, which contains 5 minute ommatidia, and on USNM 157943A, an A-1 male, the lateral eye is about twice the size of the eye of the adult female, and contains 6 larger ommatidia.

COMPARISONS.—The new species, Philomedes albatross, differs from P. brenda mainly in having elongate rather than short pegs on the tip of the 7th limb. The number of comb teeth (10–15) on the 7th limb of P. albatross is greater than that of P. brenda (7–9). In the northwest Atlantic adult females of P. albatross have smaller carapaces (length 2.24–2.56) than those of P. brenda (length 2.70–2.87 mm). P. albatross differs from P. curvata Poulsen (1962:355) in having a convex rather than concave anterior rostral margin, in having 4 rather than 3 dorsal bristles on the mandibular basale, and in having fewer furcal claws (10–11 claws compared to 14–15).

In the key below P. albatross is compared with closely related species from other geographic areas.