Rutiderma judayi Mckenzie 1965

Rutiderma judayi McKenzie, 1965

Rutiderma judayi McKenzie, 1965:58, 64, 66, fig. 3, pl. 1: fig. 2, [female holotype: USNM; type-locality: “Laguna Ojo de Liebre…Scammon Lagoon, Baja California…about 7 m”].—Kornicker, 1975b:678 [compares to R. species B].—Kornicker and Myers, 1981:2–4, 25–31, 34, figs. 15–18.

DISTRIBUTION.—Northeast Pacific in Scammon Lagoon, Baja California, Mexico; San Diego and San Clemente Island, California, U.S.A.

HABITAT.—Benthic, 7–21 m; fine to coarse sands, mostly poorly sorted, quartz and sometimes shells principle components, surface water temperature and salinity: 18.5°C–25°C, 34–37‰ lagoon organic production rate: 50 mg c/m3/day; part of lower lagoon faunal assemblage; 3 cm deep, eel grass in tide pools.

LIFE HISTORY AND ONTOGENY.—Female, male.

Rutiderma judayi McKenzie, 1965

Rutiderma judayi McKenzie, 1965:64, fig. 3, pi. 1: fig. 2.

HOLOTYPE.—USNM 110916, adult female, dry separated valves on slide, mounted appendages on slide.

TYPE-LOCALITY.—Scammon Lagoon, Baja California, Mexico.

MATERIAL EXAMINED.—Holotype. San Clemente Island, California, sta D3-73, collected by Mr. Rowe and Mr. Dorsey: USNM 158220 (BM 16a), adult male; USNM 158221 (BM 16), adult female. San Diego, Ocean Beach, 11 Nov 1970, collected by Michael Sweeney: USNM 158354, 4 specimens including 3 ovigerous females, from sta 5 C/S, washings of eel grass growing on sides of pools and channels from south side of pier 70 m from shore, 2.5 cm deep in about 0.5 m of water; USNM 158355, 3 specimens, from sta 3 C/S, from vegetation on sides of tide pools with sand-shell bottoms, near side of pier about 70 m from shore, about 0.3 m deep in 0.3–0.6 m of water.

DESCRIPTION OF ADULT MALE (Figures 15, 16).—Carapace elongate, greatest height posterior to middle, greatest width near middle; rostrum well developed; incisur forming shallow obtuse angle; caudal process projecting posteriorly.

Ornamentation (Figure 15): Anterior edge of rostrum with minute scallops; each valve with 3 horizontal ribs connected posteriorly by vertical rib having indentation between upper 2 ribs; posterior edge of upper rib projecting past posterior edge of valve; anterior end of upper 2 ribs in vicinity of central adductor muscle attachments; anterior end of lower rib at ventral end of rostrum.

Infold (Figure 16a–c): Rostral infold with 5 or 6 bristles forming row parallel to anterior margin of rostrum (Figure 16a); 2 minute bristles present at inner corner of incisur; anteroventral infold with 7 bristles forming row. Right valve: anterior ridge of caudal infold not observed except at dorsal end (Figure 16b); ridge and posterior end of ventral margin with about 14 small bristles; 2 small bristles present dorsal to dorsal end of ridge of caudal process, and 1 small bristle present posterior to ridge. Infold of caudal process of left valve similar to that of right valve except for having 16 bristles along anterior ridge and posterior end of ventral margin of valve, and for not having bristle posterior to ridge (Figure 16c).

Selvage: Wide lamellar prolongation with marginal fringe present along anterior and ventral margins becoming narrower in vicinity of caudal process where marginal fringe is absent; selvage divided at inner corner of incisur and at small bristle at posterior end of caudal process (see detail on Figure 16b).

Size: USNM 158220, length 1.03 mm, height 0.63 mm.

First Antenna (Figure 16f): 1st joint bare. 2nd joint with spines and 2 spinous bristles (1 dorsal, 1 lateral). 3rd joint with 3 bristles (1 ventral, 2 dorsal). 4th joint with 4 or 5 bristles (3 ventral, 1 or 2 dorsal). Sensory bristle of minute 5th joint with abundant long proximal filaments, 1 minute filament following long filaments, and 2 minute spines at tip of stem. Long 6th joint with spinous medial bristle. 7th joint: a-bristle about same length as bristle of 6th joint, with faint marginal spines; b-bristle about 3 times length of a-bristle, with 2 proximal filaments and spine at tip; c-bristle extremely long, with 10 marginal filaments. 8th joint: d- and e-bristles bare with blunt tips reaching well past tip of b-bristle; f-bristle extremely long, with 10 marginal filaments; g-bristle slightly longer than d-bristle, with 1 proximal filament and spine at tip.

Second Antenna: Protopodite bare. Endopodite 3-jointed (Figure 16d,e): 1st joint short, with 5 small bristles (4 proximal, 1 distal); 2nd joint elongate, with 2 slender ventral bristles near middle; 3rd joint elongate, reflexed on 2nd joint, with short proximal bristle (tip of bristle broken off on illustrated limb) and 2 slender subterminal bristles; tip of 3rd joint faintly serrate. Exopodite: 1st joint elongate, with slender spines or hairs along ventral margin and small medial bristle on distal margin; bristle of short 2nd joint reaching past distal end of long 3rd joint, and with spines along ventral margin; bristles of joints 3–8 long, with natatory hairs but no spines; 9th joint with 4 long bristles with natatory hairs and 1 minute bare bristle; joint 2 with long lateral spines forming row along distal margin; joints 3–8 with shorter lateral spines forming rows along distal margins.

Mandible: Both limbs lost.

Maxilla (Figure 16g): Limb reduced. Dorsal margins of precoxale and coxale with fringe of long hairs. Coxale with stout hirsute dorsal bristle. 3 endites with weakly developed bristles. Basale with 2 or 3 distal bristles. Exopodite with 2 bristles (1 long, 1 short). Endopodite: alpha-bristle of 1st joint not observed on limb examined, beta-bristle stout, hirsute; end joint with total of 7 bristles, some unringed, all weakly developed.

Fifth Limb (Figure 16h): Endite I with 2 or 3 bristles; endite II with 4 bristles; endite III with about 5 bristles. Exopodite: 1st joint with 4 flat unringed terminal bristles, some hirsute; 2nd joint with 1 flat unringed bristle and 2 ringed bristles. Inner lobe of 3rd joint with 4 bristles (all of these may not be on 3rd joint); outer lobe of 3rd joint with 2 stout hirsute bristles; fused 4th and 5th joints with total of 4 or 5 bristles. [Exact number of bristles on joints difficult to ascertain on mounted limb, and the numbers given above must be considered approximate.]

Sixth Limb (Figure 16i): Endite I with 3 short bristles; endite II with 1 bristle, endite III with 2 bristles; endite IV with 2 bristles; end joint with 3 slender bristles on distinct projection followed by 4 stout hirsute bristles. 1 or 2 bristles in place of epipodial appendage.

Seventh Limb (Figure 16j): 4 bristles in proximal group (2 on each side) and 4 in distal group (2 on each side); each bristle with up to 6 bells; marginal spines not observed on all bristles. Terminus consisting of opposing combs with 2 or 3 teeth on each side.

Furca (Figure 16k): Each lamella with 4 strong claws followed by 2 weak secondary claws.

Bellonci Organ (Figure 16l): Elongate, broadening in middle part distal to suture, then tapering to narrow rounded tip.

Eyes: Medial eye tapering anteriorly, with dark brown pigment and dorsal projections, some with pigment (Figure 16l,m). Lateral eye larger than medial eye, with black pigment, about 20 ommatidia (exact number difficult to determine because of pigment) (Figure 16n).

Posterior of Body: Spinous dorsal to furca.

Upper Lip (Figure 16m): Simple lobe.

Y-Sclerite (Figure 16o): Typical for genus.

DESCRIPTION OF ADULT FEMALE (Figures 17, 18).—Carapace with well-defined incisur with edge of valve forming right angle when viewed from inside (Figure 18c), and with slight overhang of rostrum laterally (Figure 17). Caudal process forming distinct posterior projection with rounded tip; carapace more rounded in lateral view than that of adult male.

Ornamentation (Figure 17): Each valve with 3 horizontal ribs connected posteriorly by vertical rib having indentation between upper 2 ribs; posterior edge of upper rib projecting past posterior edge of valve; anterior end of ribs continuing anteriorly forming walls of large reticulations; a convex ridge lying just within dorsal margin of valve with 3 small processes along posterodorsal part; a small process projecting past posterior end of valve present near middle of posterior margin; radial riblets present extending from lower horizontal rib to ridge along ventral margin of valve; additional details of ornamentation not shown in Figure 17 are abundant minute fossae on valve surface including ribs.

Infold (Figure 18c,d): Rostral infold with 7 long bristles forming row parallel to anterior margin of rostrum (not all shown in Figure 18c); 2 or 3 minute bristles present at inner corner of incisur; anteroventral infold with 8 bristles forming row. Anterior ridge of caudal process more distinct at posterior end but visible at high magnification (40× objective) at anterior end which extends considerable distance anteriorly along posterior end of ventral margin; ridge with 14 bristles on right valve of USNM 158221 (not all shown in Figure 18d) and 16 on left; 1 small bristle posterior to posterior end of ridge and 3 small bristles forming row dorsal to posterior end of ridge (Figure 18d).

Selvage: Wide lamellar prolongation present along anterior and ventral margins becoming narrower in vicinity of caudal process where marginal fringe is absent; selvage divided at inner corner of incisur and at small bristle at posterior end of caudal process (see detail on Figure 18d).

Size: USNM 158221, length 1.01 mm, height 0.76 mm. Holotype, USNM 110916, length 1.05 mm, height 0.70 mm (from McKenzie, 1965:66). USNM 158354 (3 specimens): length 0.97 mm, height 0.72 mm; length 0.96 mm, height 0.72 mm; length 0.95 mm, height 0.71 mm.

First Antenna (Figure 18e): 1st joint with short spines forming few rows. 2nd joint with 2 bristles (1 dorsal, 1 lateral) and spines forming row along distal lateral margin. 3rd and 4th joints fused; 3rd joint short with 3 bristles (2 dorsal, 1 ventral); 4th joint long, with 3 bristles (1 dorsal, 2 ventral). Sensory bristle of long 5th joint with minute proximal filament near base, and spine at tip; lateral spines forming row near base of bristle. Medial bristle of minute 6th joint short, spinous (5th and 6th joints fused). 7th joint: a-bristle spinous, about same length as bristle of 6th joint; b-bristle about twice length of a-bristle, with spine at tip; c-bristle about same length as sensory bristle of 5th joint, with spine at tip. 8th joint: d-and e-bristles slightly shorter than c-bristle, bare with blunt tips; f-bristle about twice length of b-bristle, stout with spine at tip, and with minute proximal filament; g-bristle very slightly shorter than c-bristle, with spine at tip, and proximal filament with long slender tip.

Second Antenna (Figure 18f): Protopodite bare. Endopodite single jointed with 4 short proximal anterior bristles. Exopodite: 1st joint with minute bent medial terminal bristle with blunt tip; bristle of 2nd joint reaching to about distal end of 9th joint, with a few faint proximal short ventral spines followed by row of minute blunt spines; bristles of joints 3–5 longer but with similar spines; bristles of joints 6–8 longer, with natatory hairs, but no spines; 9th joint with 6 bristles (3 long and 1 short with natatory hairs, 2 minute, bare or with few short spines).

Mandible (Figure 18g): Coxale endite well developed, bifurcate, pectinate, with long hairs at base. Basale: dorsal margin with 3 bristles (1 near middle, 2 just distal to middle); medial surface near ventral margin with 4 bristles (2 of these short, pectinate); ventral margin with 2 slender midbristles. 1st endopodial joint with medial spines and 2 small ventral bristles. 2nd endopodial joint: medial surface spinous; ventral margin with 2 short slender subterminal bristles; dorsal margin with 3 short slender proximal bristles; terminal claw stout with curved tip, serrate dorsal margin, and small proximal dorsal process; small process with minute terminal spine present medial to ventral base of terminal claw. 3rd endopodial joint with stout terminal claw with minute dorsal process near tip and spines along ventral margin; 3 slender ringed bristles and 1 spinous unringed bristle present just ventral to terminal claw and 2 short bristles located lateral to claw of 2nd joint.

Maxilla (Figure 18h): 3 endites present, each with several stout pectinate and slender ringed bristles. Coxale with short dorsal bristle and hairs near dorsal margin. Basale with 1 spinous dorsal bristle, 1 ventral bristle, and 1 lateral bristle. Exopodite with 1 short and 1 long bristle. 1st endopodial joint with 1 alpha-bristle with slender marginal spines, and 1 beta-bristle with pectinate spines proximally and slender spines distally. End joint with 2 stout pectinate bristles and 4 (possibly 5) slender spinous or pectinate ringed bristles.

Fifth Limb (Figure 18a,b): Exopodite: 1st joint with main tooth consisting of proximal small smooth tooth followed by 3 larger teeth bearing 1–3 marginal teeth (Figure 18b); 1 bristle present proximal to small smooth tooth and on edge proximal to large distal tooth. 2nd joint with large squarish tooth with 3 prongs forming inner margin (Figure 18a); posterior surface with 1 small bristle near outer corner and 2 bristles near proximal prong. 3rd joint with 2 bristles on outer lobe and 3 on inner lobe. Fused 4th and 5th joints with total of 4 bristles.

Sixth Limb (Figure 18i): Endite I with 2 short bristles, endite II with 2 bristles (1 long, 1 short), endite III and IV each with 2 long bristles, end joint with 2 long anterior bristles on projection followed by 5 hirsute bristles; 2 bristles in place of epipodial appendage.

Seventh Limb (Figure 18j): One limb with 6 distal bristles (3 on each side) and 4 proximal bristles (2 on each side); bristles spinous and with up to 6 bells; terminus with opposing combs with 3 alate teeth on 1 side and 2 on the other. Other limb obscure but may have only 5 distal bristles (2 on 1 side, 3 on other), otherwise similar to other limb.

Furca (Figure 18k): Each lamella with 4 stout claws followed by 2 small claws; long hairs at base of some stout claws and following claws.

Bellonci Organ (Figure 18l): Elongate, broadening in middle part distal to weak suture, then tapering to narrow rounded tip.

Eyes (Figure 18l): Lateral eye small, with light amber pigment and 5 small ommatidia. Medial eye larger than lateral eye, with dark brown pigment and 2 dorsal projections.

Upper Lip (Figure 18l): Simple lobe.

Remarks: The appendages on the slide of the holotype prepared by K. G. Mckenzie were examined and found to conform with the specimen described above, but the 9th joint of the only 2nd antenna on the slide is missing, and the 6th limb as well as the tip of the 7th limb are obscure.