Rutiderma arcuatilis Kornicker 1983

Rutiderma arcuatile

ETYMOLOGY.—The specific name from the Latin arcuatilis meaning bowlike, in reference to the shape of the list on the infold of the caudal process of this species.

HOLOTYPE.–USNM 158212, adult female on slides and in alcohol.

TYPE-LOCALITY.—East side of Bolongo Bay, St. Thomas Island, U.S. Virgin Islands.

PARATYPE.—USNM 158886, 1 ovigerous female from outer reef Tague Bay, St. Croix, U.S. Virgin Islands.

DISTRIBUTION.—St. Thomas and St. Croix, U.S. Virgin Islands. Known depth range intertidal to 9 m (Table 1).

DESCRIPTION OF ADULT FEMALE (Figures 39, 40).—Carapace ovoid in lateral view, with prominent caudal process, and small rostrum forming acute angle with anterior margin of valve ventral to incisur when viewed laterally (Figure 39); edge of rostrum forming right angle with anterior edge of valve ventral to incisur when viewed medially (Figure 40a).

Ornamentation (Figure 39): A horizontal rib present above and below central adductor muscle attachments forming alar process on each valve; additional ribs paralleling dorsal and anteroventral borders; faint radial ribs along anterodorsal and anteroventral borders; some of the latter extending dorsally to intersect horizontal rib below central adductor muscle attachments; 1 or 2 small processes along posterior and posterodorsal valve margins (Figures 39,40c); anterior margin of rostrum with scalloped edge (Figures 39, 40a); long bristles along anterior and ventral margins and scattered over valve surface; small, closely spaced fossae abundant on valve surface.

Infold (Figure 40a,c): Rostral infold with 10 bristles paralleling valve margin (Figure 40a); 2 additional smaller bristles at inner edge of incisur (these may be lateral to selvage); anteroventral infold with 1 short bristle just ventral to incisur and 5 or 6 fairly long bristles forming row parallel to valve edge; row of 6 similar or smaller bristles continuing onto anterior part of ventral infold; ventral infold anterior to caudal process with 7 or 8 bristles forming row; infold of caudal process of right valve with pocket having 4 small bristles along anterior edge (Figure 40b); infold of caudal process of left valve having along anterior edge a narrow skirt with 3 or 4 small bristles along its anterior edge (Figure 40c); 1 small bristle present on posterior infold just dorsal to caudal process (Figure 40b,c).

Selvage: Wide lamella prolongation with marginal fringe present along free margins; fringe longest along rostral and anteroventral margins of valves and may be absent in vicinity of caudal process; prolongation divided at inner end of incisur.

Size: USNM 158212, length 1.02 mm, height 0.72 mm; USNM 15886, length 0.92 mm, height 0.73 mm.

First Antenna (Figure 40d): 1st joint with faint medial spines forming row. 2nd joint with lateral spines forming row along distal margin, and 2 bristles (1 dorsal, 1 lateral). 3rd and 4th joints fused; 3rd joint short, with 3 bristles (1 ventral, 2 dorsal); 4th joint elongate, with 3 bristles (2 ventral, 1 dorsal). Bristle of long 5th joint with 1 small proximal filament and 1 or 2 minute processes at tip. 6th joint minute, fused with 5th joint, with short, spinous, medial bristle. 7th joint: a-bristle longer than bristle of 6th joint, with marginal spines; b-bristle about twice length of a-bristle, bare except for minute process at tip; c-bristle about same length as bristle of 5th joint, with 2 minute, distal, marginal spines, and minute process at tip. 8th joint: d- and e-bristles each about same length as c-bristle, bare with blunt tips; f-bristle about two-thirds length of c-bristle, with 2 small proximal filaments and minute process at tip; g-bristle about same length as c-bristle, with fairly long proximal filament with spinelike tip, 2 minute distal spines, and minute process at tip.

Second Antenna (Figure 40e): Protopodite bare. Endopodite 1-jointed with 4 small, proximal, anterior bristles and minute posterior process along edge. Expodite: 1st joint elongate with small distal, medial bristle having open tubelike tip and bulbous base; bristles of joints 2–5 reaching well past 9th joint, with small teeth forming row along ventral margins, but without natatory hairs; bristles of joints 6–8 long, with natatory hairs, but without spines; 9th joint with 6 bristles (2 long with natatory hairs, 1 medium with natatory hairs, 1 short with natatory hairs, 2 minute bare); joints 3–5 with minute spines forming row along distal margins.

Mandible (Figure 40f): Coxale endite bifurcate with long hairs and stout spines. Basale: dorsal margin with 3 bristles; ventral margin with 4 bristles in proximal group (2 pectinate unringed, 2 slender ringed), and 3 separated distal bristles, all ringed. 1st endopodial joint with 2 ringed ventral bristles, and medial spines. 2nd endopodial joint: medial surface spinous; dorsal margin with 3 short proximal bristles; ventral margin with 1 or 2 small terminal bristles, 1 small sclerotized process (with minute spine at tip) at base of stout terminal claw; dorsal margin of terminal claw with small proximal tooth and minute serrations. 3rd endopodial joint: stout terminal claw having truncate tip and serrate ventral margin; 3 slender medial bristles near base of claw; 1 unringed flat bristle (with serrate ventral margin) ventral to claw; 2 small lateral bristles near base of claw of 2nd joint.

Maxilla (Figure 40g): Precoxale with fringe of long hairs along dorsal margin. Endites I, II, and III each with 2 or 3 terminal claws and several slender bristles. Coxale with 1 spinous dorsal bristle. Basale with 1 dorsal bristle and 1 medial bristle near ventral margin. Exopodite small with 2 bristles. 1st endopodial joint with few long spines, 1 spinous alpha-bristle, and 1 stouter, spinous, beta-bristle. End joint with 2 stout, unringed, pectinate claws and 4 slender ringed bristles, some with marginal spines.

Fifth Limb (Figure 40h,i): Endite I with 3 bristles; endite II with 4 bristles; endite III with 8 bristles. Exopodite: 1st joint with 3 stout teeth followed by 1 smaller smooth tooth and 1 short ringed bristle; outer edge of joint with 1 short ringed bristle (Figure 40i). 2nd joint with large 3-lobed tooth (proximal 2 lobes without secondary teeth; distal lobe with 2 secondary teeth along inner edge); posterior side of joint with small bristle near outer corner and with 2 bristles near proximal lobes of 3-lobed tooth. 3rd joint with 3 bristles on inner lobe and 2 on outer lobe. 4th and 5th joints fused, with 1 proximal and 4 terminal bristles (the proximal bristle of fused 4th and 5th joints could be interpreted as being on 2nd joint).

Sixth Limb (Figure 40j): Endite I with 3 bristles; endite II with 2 bristles; endites III and IV each with 3 bristles; end joint with anterior projection with 3 bristles (with short marginal spines) followed by 4 bristles (anterior 2 of these with long proximal hairs and short distal spines, posterior 2 with long marginal hairs); 2 spinous bristles in place of epipodial appendage.

Seventh Limb (Figure 40k): Each limb with 4 proximal bristles (2 on each side) and 6 terminal bristles (3 on each side); each bristle with up to 5 bells and marginal spines; terminus with opposing combs, with about 5 alate teeth in one comb and 4 simple teeth in other.

Furca (Figure 40l): Each lamella with 4 strong claws followed by 2 weak secondary claws; long hairs along edge of lamella following claws and medially at bases of claws.

Bellonci Organ (Figure 40m): Elongate, broadening near middle, then tapering to rounded tip.

Eyes (Figure 40m,n): Medial eye with light amber pigment; dorsal margin with numerous filamentous growths (Figure 40m). Lateral eye minute with 4 ommatidia, and without pigment (Figure 40n).

Upper Lip (Figure 40m): Rounded

Posterior of Body: Hirsute.

Eggs: USNM 158212 with large unextruded eggs; USNM 158886 with 3 large eggs.

Gut Content: Large copepod fragments in USNM 158212.

COMPARISONS.—The new species R. arcuatile is closely related to R. dinochelatum. On R. arcuatile the curvature of the list of the caudal process has a low angle with the ventral margin. On both R. dinochelatum and R. mortenseni (only male known), the curvature of the list forms about a 45° angle with the ventral margin. Also, on both of these species, bristles are present on each end of the curved list, whereas, R. arcuatile bears several bristles along the list.

Rutiderma arcuatile Kornicker, 1983

Rutiderma arcuatile Kornicker. 1983:11–I 3, 25, 67–70. figs. 39, 40 [female holotype: USNM; type-locality: “East side of Bolongo Bay, St. Thomas Island, U.S. Virgin Islands…18°18′59″N, 64°53′45″W…intertidal”].

DISTRIBUTION.—Northwest Atlantic: Virgin Islands: St. Croix and St. Thomas Islands.

HABITAT.—Benthic, intertidal, shifting sands by rocks; planktonic near bottom, 9 m, outer reef.

LIFE HISTORY AND ONTOGENY.—Female, 3 eggs.

STOMACH CONTENTS.—Copepods.

Rutiderma chessi Kornicker and Myers, 1981

Rutiderma chessi Kornicker and Myers, 1981:2, 3, 31–34, figs. 19, 20 [female holotype: USNM; type-locality: “San Clemente Island, sta D-3”].

DISTRIBUTION.—Northeast Pacific: off California, U.S.A.: San Clemente Island.

LIFE HISTORY AND ONTOGENY.—Female, 4 eggs.