Rutiderma gyre Kornicker 1983

Rutiderma gyre

ETYMOLOGY.—The species is named for the ship from which specimens were collected, R/V Gyre.

HOLOTYPE.—USNM 157988, 1 ovigerous female in alcohol (body partly removed from carapace; valves separated).

TYPE-LOCALITY.—Gulf of Mexico off Galveston, Texas, R/V Gyre, cruise 10, sta 16, 53.5 m.

PARATYPES.—Florida continental shelf (Atlantic): USNM 158363, 1 ovigerous female, from “Jeff's Reef”. Returned to John E. Miller, 2 juveniles from off Pepper State Park.

Florida continental shelf (Gulf of Mexico), transect I: USNM 158675, 159721, 2 specimens, sta 2104. Transect II: USNM 158717, 158719, 158656, 158654, 158657, 158741, 7 specimens, sta 2211. Transect VII: USNM 158824, 1 ovigerous female, sta 2748.

Southwest Florida; returned to James K. Culter, 18 specimens, sta 4; 3 specimens, sta 16; 2 specimens, sta 20; 6 specimens, sta 22; 21 specimens, sta 28; 1 specimen, sta 37.

Alabama continental shelf, transect VI: USNM 158747, 1 specimen, sta 2643.

Louisiana Continental Shelf, Sonnier Bank: USNM 157999, 1 ovigerous female; USNM 158000, 1 adult, male; sta THR-1. USNM 158850, 1 specimen, sta THR-2.

Texas continental shelf, East Flower Garden: USNM 158841, 1 adult male, sta EFG-4; USNM 158833, 1 ovigerous female, sta 902-3. “28 Fathom Bank”: USNM 158646, 3 specimens, sta 3-1. USNM 158647, 2 specimens, sta 3-2. USNM 158644, 1 specimen, sta 3-3. USNM 158649, 2 specimens, sta 3-4. Southwest peak: USNM 158652, 1 specimen, sta 2 D. Cruise 10: USNM 157875, 2 specimens; USNM 157991, 1 ovigerous female; sta 16. Cruise 11: USNM 157420, 1 juvenile; USNM 154185, 1 adult female, sta 5. USNM 157993, 1 adult male, sta 7. Stetson Bank: USNM 158641, 3 specimens, sta STB-1A. USNM 158639, 2 specimens, sta STB-1B. USNM 158640, 2 specimens, sta STB-2B. USNM 158633, 1 specimen, Sta STB-2C. USNM 158638, 4 specimens, sta STB-2D. USNM 158636, 1 specimen, sta STB-2E. USNM 158635, 8 specimens, sta STB-2F. USNM 158643, 1 specimen, sta STB-4A. USNM 158634, 4 specimens, sta STB-4B. USNM 158642, 2 specimens, sta STB-4C.

South Texas shelf, transect HR, sta 1: USNM 159034-1, 1 specimen; USNM 159043-2, 1 adult female; USNM 159044-2, 1 adult female; USNM 159024-2, 1 juvenile male; USNM 159033-3, 1 juvenile; USNM 159031-4, 5 specimens; USNM 159030-5, 1 adult male + 2 juveniles; USNM 159027-6, 2 juveniles; USNM 159053-6, 1 adult female; USNM 159050-2, 1 ovigerous female + 1 adult female; USNM 159051-4, 1 adult female + 1 juvenile male; USNM 159057-4, 1 adult male; USNM 159067-5, 1 juvenile male; USNM 159049-6, 2 juveniles. Sta 2: USNM 159048-3, 1 adult male.

South Texas, transect SB, sta 3; USNM 159037-6, 1 ovigerous female + 1 juvenile; USNM 159029-1, 1 juvenile; USNM 159040-3, 1 juvenile; USNM 159026-4, 1 adult male + 1 juvenile male; USNM 159028-5, 4 specimens; USNM 159036-6, 6 specimens; USNM 159056-2, 1 adult male; USNM 159018-3, 1 adult male; USNM 159061-4, 1 adult male; USNM 159051-5, 1 adult female + 1 juvenile; USNM 159052-6, 1 juvenile.

DISTRIBUTION.—Continental shelves of Florida (Atlantic and Gulf of Mexico), Alabama, Louisiana, and Texas (Figure 4). Known depth range 6.1–148.0 m (Table 1).

DESCRIPTION OF ADULT FEMALE (Figures 30–32; Plate 3).—Carapace with well-defined incisur, overhanging rostrum, and well-developed, triangular caudal process. Ventral margin with slight concavity just anterior to tip of caudal process.

Ornamentation: 2 well-developed longitudinal ribs present, 1 above and 1 below the central adductor muscle attachments (Figure 30, Plate 3a); posterior end of each rib with small process; rarely with vertical rib anterior to central adductor muscle; minute scallops along margin of rostrum and ventral margin of valve; small process present on posterodorsal margin of valve dorsal to posterior end of upper rib; surface of valve with shallow fossae with narrow peripheral rim (Plate 3b–d); bristles widely scattered on valve surface and forming row along anterior and ventral margins (Plate 3f).

Infold: Rostral infold with 7–9 bristles parallel to anterior margin; 2 minute bristles at inner end of incisur (Figure 31a); anteroventral infold with 9 bristles forming row, and 6 ridges paralleling inner edge of infold; posterior end of ventral infold near caudal process with 10 small bristles forming row along faint list; anterior part of caudal process with crescentic list having small bristle at upper and lower end (Figure 31b); pocket posterior to list of caudal process with 2 or 3 small bristles; infold of caudal process similar on left and right valves; inner edge of infold dorsal to list of caudal process with small slender bristle.

Selvage: Broad lamellar prolongation with marginal fringe present along anterior and ventral valve margins; narrow bare lamellar prolongation along margin of caudal process; lamellar prolongation divided at inner end of incisur.

Size: USNM 154185, length only 1.10 mm; USNM 157988, length 1.08 mm, height 0.76 mm; USNM 157999, length 1.09 mm, height 0.75 mm; USNM 158363, length 1.15 mm, height 0.86 mm. Returned to Mote Marine Laboratory, sta 28F, length 1.16 mm, height 0.78 mm.

First Antenna (Figure 31c): 1st joint with spines forming few rows on medial and lateral surfaces. 2nd joint with spines on dorsal margin and on distal lateral surface, and with 2 spinous bristles, 1 dorsal, 1 lateral. 3rd and 4th joint fused; 3rd joint with 3 bristles, 1 ventral, 2 dorsal; 4th joint with 3 bristles, 1 dorsal, 2 ventral (longer of these about 3 times length of other). Long 5th joint with faint lateral hairs in distal ventral corner; sensory bristle with 1 small proximal filament and bifurcate tip, each with terminal spine. Bristle of minute 6th joint small spinous. 7th joint: a-bristle spinous, about one-fourth longer than bristle of 6th joint; b-bristle slightly longer than a-bristle, with spine at tip; c-bristle slightly shorter than sensory bristle of 5th joint, with minute proximal filament, and bifurcate tip. 8th joint: d- and e-bristles bare with blunt tips, bristles about same length as c-bristle; f-bristle stout, more than twice length of b-bristle, with bifurcate tip; g-bristle about same length as c-bristle, with fairly long proximal filament and bifurcate tip.

Second Antenna (Figure 31d): Protopodite bare. Endopodite 1-jointed with 4 small anterior bristles. Exopodite: 1st joint with 1 minute medial bristle on terminal margin; bristles of joints 2–5 fairly short, with ventral spines but no natatory hairs; bristles of joints 6–8 long, with natatory hairs but no ventral spines; 9th joint with 5 bristles (3 long with natatory hairs, 1 medium with natatory hairs, 1 minute and bare).

Mandible (Figure 31e): Coxale endite bifurcate, pectinate. Basale: ventral margin with 4 proximal bristles (2 pectinate, unringed), and 2 bristles proximal to middle; dorsal margin with 3 bristles distal to middle; lateral side with 1 small proximal bristle near ventral margin. 1st endopodial joint with 2 short ventral bristles, and medial spines forming rows. 2nd endopodial joint: dorsal margin with 3 short proximal bristles; medial surface with abundant spines; ventral margin with 2 minute distal bristles, and small oval sclerotized process with minute bristle at base of stout terminal claw; dorsal margin of terminal claw with proximal tooth, serrate margin, and short curved tip. 3rd endopodial joint with stout terminal claw with truncate tip and serrate ventral margin, 3 slender medial bristles near ventral end of base of stout claw, 1 unringed flat bristle (with serrate ventral margin) ventral to stout claw, and 2 short spinous bristles located lateral to stout terminal claw of 2nd joint.

Maxilla (Figure 32a): Dorsal margin of coxale with 1 bristle and fringed lamellar prolongation. Endites I to III each with 3 stout pectinate, unringed bristles, and several ringed spinous bristles. Basale with 1 dorsal bristle and 1 medial bristle near ventral margin. 1st endopodial joint with 1 alpha-bristle, 1 spinous beta-bristle, and 1 proximal medial bristle (possibly this bristle is on basale). 2nd endopodial joint with 2 stout pectinate unringed bristles and 5 spinous ringed bristles. Exopodite small with 2 bristles.

Fifth Limb (Figure 32b,c): Endite I with 2 or 3 short bristles; endite II with 5 bristles; endite III with 8 bristles. Exopodite: 1st joint with 3 stout teeth with secondary teeth distal to 1 smooth smaller tooth and 1 spinous bristle; outer edge of joint with 1 proximal bristle. 2nd joint with large 3-lobed tooth; proximal 2 of the lobes with secondary teeth; posterior side of joint with minute faint bristle near outer corner; inner margin of joint with 2 proximal bristles. 3rd joint with 2 bristles on outer lobe and 3 on inner lobe. 4th and 5th joints fused, with total of 4 or 5 bristles. Epipodial appendage with about 35 bristles.

Sixth Limb (Figure 31f): Endite I with 3 bristles; endites II and II each with 2 bristles; endite IV with 2 or 3 bristles; end joint with 3 anterior bristles with spines and hairs and 4 or 5 stouter hirsute posterior bristles; posterior edge of stem with 1 or 2 spinous epipodial bristles.

Seventh Limb (Figure 32d): Each limb with 4 proximal bristles, 2 on each side, and 6 terminal bristles, 3 on each side; each bristle with up to 4 bells and distal marginal spines; terminus with opposing combs, each with several teeth.

Furca (Figure 31g): Each lamella with 4 stout primary claws followed by 2 small secondary claws; claw 1 with anterior distal hairs and both long and short posterior teeth; anterior margin of lamellae with slender spines; long hairs on lamellae following claws and medially at bases of claws.

Bellonci Organ (Figure 32e,f): Elongate, widening near middle, with tip tapering to point.

Eyes: Medial eye tapering distally, with brown pigment (Figure 32e,f). Lateral eye smaller than medial eye, with 4 small ommatidia (Figure 32e, all ommatidia not shown in illustrated eye).

Genitalia (Figure 31g): Consisting of small sclerotized oval on each side of body.

Y-Sclerite (Figure 31g): Typical for genus.

Eggs: USNM 154185 and 157988, each with 1 well-developed egg in marsupium; USNM 157991 with 2 eggs; USNM 157999 with 4 eggs.

DESCRIPTION OF ADULT MALE (Figures 33–35).—Carapace elongate with prominent rostrum and caudal process with narrowly rounded tip; tip of rostrum slightly overhanging valve edge (Figures 33, 34a,e,f).

Ornamentation: Posterior half of each valve with 2 horizontal ribs forming alar process; surface with abundant shallow fossae (Figure 33); long bristles present along anterior and anteroventral margins and scattered over valve surface.

Infold: Infold of rostrum with 6–8 long bristles forming row parallel to edge of rostrum (Figure 34a); 2 short bristles present at inner corner of incisur; anterior infold below rostrum with 2 short bristles; anterior part of ventral margin with 5–7 short bristles forming row. Infold of caudal process with “pocket” having a well-defined anterior ridge with a small bristle at its ventral and dorsal ends (bristle at dorsal end very faint) (Figure 34b,g,h); infold posterior to ridge with 1 or 2 small bristles; infold along ventral margin of valve anterior to ridge with 8–10 bristles.

Selvage: Wide lamellar prolongation along anterior and ventral margins becoming narrower posteriorly and on caudal process; prolongation fringed except in vicinity of caudal process; prolongation divided at inner end of incisur and on ventral margin near tip of caudal process where it is interrupted by a short bristle on valve edge (Figure 34g,h).

Size: USNM 158000, length 1.17 mm, height 0.66 mm; USNM 157993, length 1.12 mm, height 0.68 mm. Specimens returned to the Mote Marine Laboratory, sta 22, length 1.19 mm, height 0.68 mm; sta 28 C: length 1.20 mm, height 0.68 mm; length 1.18 mm, height 0.68 mm.

First Antenna (Figure 34i): 1st joint with few spines forming rows on medial side. 2nd joint spinous, with 2 bristles (1 dorsal, 1 lateral). 3rd and 4th joints with separating suture only on medial side; 3rd joint with 3 bristles (1 ventral, 2 dorsal); 4th joint with 4 bristles (3 ventral, 1 dorsal). 5th joint small, wedged ventrally between 4th and 6th joints; sensory bristle with stout, cylindrical, proximal part with abundant distal filaments (not shown in illustrated limb), and distal stem with minute filament near middle and bifurcate tip. Elongate 6th joint with medial bristle at distal dorsal corner. 7th joint: a-bristle slightly longer than bristle of 6th joint; b-bristle about twice length of a-bristle, with 3 filaments near middle (2 short, 1 minute); c-bristle extremely long, with 12 marginal filaments, each with 2 spines at tip. 8th joint: d- and e-bristles bare with blunt tips, about same length as b-bristle; f-bristle similar to c-bristle; g-bristle slightly longer than b-bristle, with 2 marginal filaments and bifurcate tip.

Second Antenna: Protopodite bare. Endopodite 3-jointed (Figure 34j): 1st joint short with 5 bristles (4 proximal, 1 near middle); 2nd joint elongate with 2 spinous bristles near middle; 3rd joint elongate, reflexed, with 1 short, spinous, proximal bristle and 2 small bristles near rounded tip (tip with faint ridges). Exopodite: 1st joint elongate with minute, faint, medial bristle at tip, and few distal hairs near ventral margin; 2nd joint short, with bristle having same length as combined length of 3rd and 4th joints, with minute ventral spines and sharply pointed tip; 3rd joint elongate, with long natatory bristle without spines; joints 4–9 short, decreasing in size distally; joints 4–8 each with long bristle with natatory hairs; 9th joint with 5 bristles (3 long and 1 medium, all with natatory hairs, and 1 minute, bare); joints 2–8 with spines forming row along distal lateral edge.

Mandible (Figure 35a): Coxale with 2 or 3 minute medial spines representing endite. Basale: medial side spinous, with 5 or 6 bristles near ventral margin (one of the proximal bristles faint, unringed); dorsal margin with 3 bristles distal to middle. Exopodite well developed, hirsute distally. First endopodial joint with medial spines and 2 ventral bristles. Second endopodial joint: medial side spinous; dorsal margin with 3 proximal bristles; ventral margin (or close to it) with 6 short distal bristles. End joint with 1 stout claw and 5 slender bristles.

Maxilla (Figure 35b): Limb reduced. Endites I to III with faint bristles, some unringed, flattened, others ringed, hirsute. Precoxale and coxale with dorsal fringe of hairs; coxale with stout hirsute dorsal bristle. Basale with 1 bare dorsal bristle, 1 spinous posterior medial bristle, and 1 short lateral bristle near base of exopodite. Exopodite with 2 or 3 bristles (1 of these long hirsute). Endopodite: 1st joint with 1 spinous alpha-bristle and 1 spinous beta-bristle; end joint with about 7 weakly developed bristles.

Fifth Limb (Figure 35c): Endite I with 3 short bristles; endite II with 4 bristles; endite III with about 7 bristles (all bristles not shown on illustrated limb). Exopodite: joints 1 and 2 each with about 4 bristles, some unringed, flattened; joint 3 with 2 stout hirsute bristles, on outer lobe and about 2 slender bristles on inner lobe; remaining joints fused, with total of 4 bristles.

Sixth Limb (Figure 35d): 2 hirsute bristles in place of epipodial appendage. Endite I with 3 short bristles; endites II and III each with 2 bristles; endite IV with 3 bristles. End joint with 3 spinous bristles on anterior projection followed by 4 stout hirsute bristles.

Seventh Limb (Figure 35e): 4 proximal bristles, 2 on each side, and 4 longer terminal bristles, 2 on each side; proximal bristles with 2 or 3 bells and distal marginal spines; terminal bristles with 4 or 5 bells and distal marginal spines. Terminus with opposing combs having 2 or 3 teeth on one comb and 3 or 4 on other comb.

Furca (Figure 35f): Similar to that of adult female, except teeth along claw 1 about same size, and main claws more slender.

Bellonci Organ (Figure 34c,k): Broadening near middle and then tapering to either pointed or rounded tip.

Eyes (Figure 34c,k): Lateral eye pigmented black, with about 16 ommatidia. Medial eye pigmented brown, about same size as lateral eye; without hairs but with minute dorsal protuberance.

Upper Limb (Figure 34k): Helmet-shaped, hirsute.

Genitalia (Figures 34d, 35g,f): Copulatory limbs well developed, each with several bristles and sclerotized process at tip.

Y-Sclerite (Figure 35g,f): Similar to that of female.

COMPARISONS.—The infold of the caudal process of the left valve of the new species R. gyre does not have the flat spines present on the left valve of R. darbyi. R. mortenseni Poulsen, 1965, is known only from a single adult male. The male of R. gyre differs from the male of R. mortenseni in having 6–8 rather than 10–12 bristles forming a row on the rostral infold. Other differences between the males of these 2 species, which I consider less reliable because they are more likely to be the result of variability or lack of observation, are as follows (data on R. mortenseni from Poulsen, 1965:38–40).

Character R. mortenseni R. gyre

Second antenna, bristle of 2nd exopodial joint bare (B) or with spines (S)

B S

Mandible, total number of bristles and claws on end joint

5 6

Fifth limb, bristles on outer lobe of 3rd exopodial joint bare (B) or hirsute (H)

B H

Rutiderma gyre Kornicker, 1983

Rutiderma gyre Kornicker, 1983:4–8, 10–13, 15, 25, 54–62, 80, figs. 3035, pl. 3 [female holotype: USNM; type-locality: “Gulf of Mexico off Galveston, Texas…28°10′N, 94°18′W; 53.5 m”].

DISTRIBUTION.—Northwest Atlantic: Florida shelf, U.S.A.; predominantly Gulf of Mexico: Florida to Texas.

HABITAT.—Benthic; 6.1–148 m.

LIFE HISTORY AND ONTOGENY.—Female, male, 1–4 eggs.