Rutiderma rotundum Poulsen 1965

Rutiderma rotundum Poulsen, 1965

Rutiderma rotunda Poulsen, June 10, 1965:7, 8, 17, 18, 22, 34–38, 43, 455, figs. 9, 10 [female holotype: Zoolog. Mus. Univ. Copenhagen; type-locality: “La Jolla, California, shallow water”].—Cohen and Kornicker, 1975:21, 26.—Kornicker, 1975b:70, 74, 80, 673; 1985:14.

Rutiderma californica McKenzie, July 15, 1965:58, 65, 66, fig. 4; pl. 1: fig. 1 [female holotype: USNM; type-locality: “Laguna Ojo de Liebre…Scammon Lagoon, Baja California, Mexico”].—Kornicker, 1975b:673 [compares to R. ovata].

Rutiderma rotundum.—Kornicker and Myers, 1981:2, 3, 18–25, figs. 11–14.

DISTRIBUTION.—Northeast Pacific: California, U.S.A: off La Jolla (Poulsen), Irvine Beach, Ocean Beach (San Diego), between Newport Beach and Laguna Beach; Mexico: Scammon Lagoon, Baja California.

HABITAT.—Benthic; 0.3–less than 22 m; shallow water, rocks with algae, eel grass, tide pools; fine to coarse sand, mostly poorly sorted, mainly quartz or shell, 18.5°C surface water, surface salinity 34–37‰, productivity about 50 mg c/m3/day; eel grass and tide pool vegetation.

LIFE HISTORY AND ONTOGENY.—Females, male, juvenile females, 2–4 eggs.

Rutiderma rotundum Poulsen, 1965

Rutiderma rotunda Poulsen, 1965:35, figs. 9, 10.

Rutiderma californica McKenzie, 1965:66, fig. 4, pl. 1: fig. 1.

HOLOTYPE.—Female, length 1.2 mm, Zoological Museum, Copenhagen.

TYPE-LOCALITY.—La Jolla, California, shallow water between rocks and algae (Poulsen, 1965:35, 37).

MATERIAL EXAMINED.—USNM 110911, holotype of Rutiderma californica (shells dry, appendages on 2 slides). Irvine Beach, California, 33°32'20″N, 116°49'00″W, 31 May 1976: USNM 158214 (BM 12), ovigerous female; USNM 158215, adult male; BM 36–39, 41, 5 adult females; BM 40, juvenile male. San Diego, Ocean Beach, 11 Nov 1970, collected by Michael Sweeney: USNM 158356, 4 specimens including 1 ovigerous female, sta 5 C/S, from 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 158357, 6 specimens, 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. USNM 158353, 7 specimens including ovigerous females + 1 left valve, exact locality unknown, but from off southern California between Newport Beach and Laguna Beach, collected by personnel of Marine Biological Consultants, Inc.

SUPPLEMENTARY DESCRIPTION OF ADULT FEMALE (Figures 11,12).—Shape and ornamentation as shown in Figure 11, which is right view of whole carapace. (The photograph illustrated by McKenzie (1965:pl. 1: fig. 1) shows the left view of a carapace. The drawing of Poulsen (1965: fig. 9a) shows only the major ridges.)

Infold (Figure 12a,b): Anterodorsal margin dorsal to minute incisur with 7 bristles; anterior margin ventral to incisur with 6–10 bristles (Figure 12a does not show all bristles); caudal process of both left and right valves with anterior ridge bearing 4 or 5 small bristles, and with 1 small bristle posterior to dorsal end of ridge; about 9 small bristles forming row along ventral margin of valve just anterior to caudal process; 3 small bristles present on posterior infold just dorsal to caudal process (Figure 12b).

Selvage: Wide lamellar prolongation along free margins of each valve; edge of lamellar prolongation with long fringe along anterior margin and anterior part of ventral margin; fringe becoming shorter posteriorly along ventral margin; fringe absent on prolongation around edge of caudal process; prolongation divided at bristle located at edge of caudal process (see detail of Figure 12b).

Central Adductor Muscle Attachments (Figure 12c): Consisting of 15 or 16 individual scars.

Size: USNM 158214, length 1.33 mm, height 1.04 mm. 5 additional specimens (BM 36,37,38,39,41): length 1.31 mm, height 1.02 mm; length 1.34 mm, height 1.03 mm; length 1.33 mm, height 1.02 mm; length 1.22 mm, height 0.96 mm; length 1.23 mm, height 0.97 mm. USNM 158356, length 1.17 mm, height 0.93 mm. Poulsen (1965:37) gave the length of mature females as 1.10–1.33 mm (mean length 1.24 mm, mean height 0.98 mm). McKenzie (1965:66) gave the measurements of a female as length 1.25 mm, height 0.95 mm.

First Antenna (Figure 12d): 1st joint with few spines on medial and lateral surfaces; 2nd joint with few lateral and medial spines near and along dorsal margin, short lateral spines forming row near distal margin, and 2 short spinous bristles (1 dorsal, 1 lateral). 3rd and 4th joints fused; short 3rd joint with 3 spinous bristles (2 dorsal, 1 ventral); long 4th joint with 3 spinous bristles (1 dorsal, 2 ventral). Sensory bristle of long 5th joint with 3 small proximal filaments. 5th and 6th joints fused; minute 6th joint with 1 short spinous medial bristle. 7th joint: a-bristle short, spinous, slightly longer than bristle of 6th joint; b-bristle only slightly longer than a-bristle, bare; c-bristle slightly shorter than sensory bristle of 5th joint, with 1 short proximal filament. 8th joint: d- and e-bristles bare with blunt tips not quite reaching tip of c-bristle; f-bristle tending to be clawlike, bare, stout, about twice length of b-bristle; g-bristle also tending to be clawlike, longer than f-bristle, with 2 short proximal filaments. [The 1st antenna of USNM 158214 differs from that described and illustrated by Poulsen (1965:35, fig. 9d) in having spines on the 1st and 2nd joints, in not having hairs on the dorsal margin of the 5th joint; in having 3 proximal filaments on the sensory bristle of the 5th joint, in having 1 short proximal filament on the c-bristle of the 7th joint, and 2 proximal filaments on the g-bristle of the 8th joint; also, all bristles of joints 2–6 bear marginal spines.]

Second Antenna: Protopodite bare. Endopodite 1-jointed with 4 small anterior bristles (Figure 12e). Exopodite: 1st joint long, with 1 minute curved medial bristle on distal margin; bristles of joints 2–5 with minute pearl-like row of teeth along ventral margins, and 4–7 larger blunt ventral teeth just proximal to recurved tip of bristles; bristles of joints 6–8 with natatory hairs and without ventral teeth or recurved tip; 9th joint with 4 bristles with natatory hairs and 2 minute bare bristles. [The 2nd antenna of USNM 158214 differs from that described and illustrated by Poulsen (1965:37, fig. 9e) in having 4 bristles on the endopodite, in having minute row of pearl-like teeth along ventral margins of bristles on 2nd to 5th exopodial joints, and in having 2 minute as well as 4 long bristles on the 9th exopodial joint. McKenzie (1965, fig. 4e) illustrated an endopodite with 3 bristles, and described (p. 66) the margins of the distal annulated setae of the exopodite as having bluntly serrated extremities. My (LSK) examination of his specimen, USNM 110911, revealed 2 minute bristles on the 9th exopodial joint and minute rows of pearl-like teeth along ventral margins of some bristles; I could not with certainty determine whether the endopodite has 3 or 4 bristles.]

Mandible (Figure 12f): Coxale endite bifurcate, pectinate with hairs near base. Basale: proximal ventral margin with 2 short pectinate bristles and 2 slender bristles (bases actually on medial surface); medial side near middle of ventral margin with 2 slender bristles with faint marginal spines; dorsal margin with 3 bristles; lateral side near middle of ventral margin with 1 short bristle. 1st endopodial joint: short ventral margin with 2 small bristles; medial surface with abundant spines forming rows. 2nd endopodial joint: dorsal margin with 4 small proximal bristles; ventral margin with 1 small subterminal bristle; dorsal margin of terminal claw with small proximal process and minute serrations; tip of claw recurved but not extended; small process with spine present medially at base of claw. 3rd endopodial joint: stout claw with minute teeth along ventral margin and small process at distal curvature of dorsal margin; stout unringed bristle with teeth along ventral margin present just ventral to terminal claw; 3 medial and 2 hirsute lateral bristles present ventral to base of claw. [The mandible of USNM 158214 differs from that illustrated by Poulsen (1965:fig. 9f) in having a small lateral bristle near ventral margin of the basale, in having medial spines on the 1st endopodial joint, and in having 4 proximal bristles on the dorsal margin of the 2nd endopodial joint. I examined the specimen described by McKenzie (1965:66, fig. 4f; USNM 110911) and observed the specimen to have 4 proximal bristles on the dorsal margin of the 2nd endopodial joint, and claws on the 2nd and 3rd endopodial joint similar to those of USNM 158214.]

Maxilla (Figure 12g): 3 endites, each with 2 or 3 stout pectinate bristles and 2 or 3 slender spinous bristles; endite III with 1 proximal bristle on lateral side. Coxale with 1 spinous dorsal bristle. Basale with 1 dorsal and 1 ventral bristle. Exopodite with 3 bristles (2 long, 1 short). 1st endopodial joint with 1 spinous alpha-bristle and 1 spinous beta-bristle. 2nd endopodial joint with 2 spinous alpha-bristles, 2 stout, pectinate, end bristles, and 3 additional spinous bristles. [The maxilla of USNM 158214 differs from that described and illustrated by Poulsen (1965:37, fig. 9g) in having 3 bristles on the exopodite, in having 1 dorsal bristle on the basale, and in not having a proximal bristle on the dorsal margin of the 1st endopodial joint. I could not determine the number of exopodial bristles on the maxilla of the specimen described by McKenzie (1965: 66; USNM 110911), but the appendage is similar to that of USNM 158214.]

Fifth Limb (Figure 12h–k): Endite I with 3 bristles (2 missing on illustrated limb); endite II with 4 or 5 bristles; endite III with 6 bristles (Figure 12h). Main tooth of 1st exopodial joint consisting of 3 teeth with secondary teeth followed by a smooth peg and then a short bristle; outer margin proximal to distal tooth with 1 short bristle (Figure 12i). 2nd exopodial joint forming large tooth with 3 smooth lobes; posterior side of 2nd joint with 1 minute bristle near distal outer corner, and 2 bristles near proximal tooth of inner margin (Figure 12k). Inner lobe of 3rd joint with 4 bristles, outer lobe with 2 bristles. Fused 4th and 5th exopodial joints with total of 4 bristles (Figure 12h). [It is unusual to have 4 bristles on the inner lobe of the 3rd joint; it is possible that 1 or 2 of the bristles are actually on the inner margin of the 2nd joint; in general, the limb of USNM 158214 resembles fairly closely that described and illustrated by Poulsen (1965:37, fig. 9h). I examined the specimen described by McKenzie (1965:66; USNM 110911) and found the teeth of the 1st and 2nd exopodial joints similar to those of USNM 158214.]

Sixth Limb (Figure 12l): Endite I with 3 short bristles; endite II with 2 bristles; endite III with 3 bristles; endite IV with 2 or 3 bristles. End joint with 3 anterior bristles with short marginal spines followed by 1 bristle with long proximal hairs and short distal spines, and 2 posterior bristles with abundant long marginal hairs. 2 short bristles present in place of epipodial appendage. [The 6th limbs of USNM 158214 closely resemble that described and illustrated by Poulsen (1965:37, fig. 9i) except for not having 2 short bristles on endite II.]

Seventh Limb (Figure 12m): Each limb with 6 distal bristles (3 on each side) and 6 proximal bristles (3 on each side); each bristle with up to 5 bells and marginal spines proximal to bells. Terminus consisting of opposing combs, each with about 8 teeth.

Furca (Figure 12n): Furca of USNM 158214 with 3 strong and 3 weak claws on left lamella and 3 strong claws and 4 weak claws on right lamella (Figure 12n). Of 5 additional adult females examined (BM 36–39,41), four had 3 strong and 3 weak claws on each lamella, and one had 3 strong claws and 2 weak claws on each lamella. The usual number of claws would appear to be 3 strong claws followed by 3 weak claws. [Poulsen (1965:37, fig. 9k) described the furca of R. rotunda as having 3 strong claws followed by 2 weak claws. McKenzie (1965:66) stated that the furca was missing on the single specimen in his collection.]

Bellonci Organ (Figure 12o): Elongate with suture proximal to middle followed by broad middle part, then tapering to pointed tip.

Eyes (Figure 12o): Medial eye with brown pigment and pointed dorsal process; lateral eyes small, pigmented brown, each with 3 ommatidia. [The lateral eye illustrated by Poulsen (1965: fig. 9a) has many ommatidia.]

Posterior of Body (Figure 12n): Hirsute posterior to furca.

Upper Lip (Figure 12p): Simple lobe with few small spines forming rows.

Y-Sclerite: Typical for family.

Eggs: USNM 158214 with 4 eggs in marsupium. [Poulsen (1965:37) reported 2–4 eggs in brood chamber of specimens he examined.]

Epizoa: USNM 158214 with protistans attached to dorsal and posterior sides of left valve. Attachments appear coiled (Figure 12q).

DESCRIPTION OF ADULT MALE (Figures 13, 14).—Shell elongate with prominent rostrum and shallow incisur (Figure 13). Posteroventral corner evenly rounded with very narrow caudal process.

Ornamentation: A smoothly rounded alar projection present on posterior part of each valve (Figure 13). A low narrow continuous ridge present just within and parallel to anterodorsal, anterior and ventral margins. Valve surface with minute fossae but appearing smooth. Numerous bristles forming row along anterior and ventral margins.

Infold (Figure 14a,b): Rostral infold with 6 or 7 long bristles forming row; 1 small bristle present near outer edge in vicinity of incisur; anteroventral infold including anterior part of ventral margin with 5 short bristles; infold of narrow caudal process of both left and right valves with 4 minute bristles along inner ridge and 1 smaller bristle posterior to dorsal end of ridge; 7 slender bristles forming row along inner edge of infold of ventral margin just anterior to caudal process.

Selvage: Wide lamellar prolongation with long marginal fringe present along anterior and ventral margins; prolongation in vicinity of caudal process and along posterior valve margin narrow and without fringe; prolongation divided at inner end of incisur, and also at small bristle located at edge of caudal process (see detail of Figure 14b).

Central Adductor Muscle Attachments (Figure 14c): Consisting of about 17 oval attachments.

Size: USNM 158215, length 1.24 mm, height 0.77 mm.

First Antenna (Figure 14d): 1st joint bare. 2nd joint with 2 short spinous bristles (1 dorsal, 1 lateral), long ventral hairs, distal lateral spines, and proximal medial spines. 3rd joint with 2 dorsal bristles (usual ventral bristle missing on both limbs of USMN 158215, possibly broken off), and long lateral spines forming rows. 4th joint with dorsal and lateral spines and 4 bristles (1 dorsal, 3 ventral). Sensory bristle of minute 5th joint with numerous long proximal filaments followed closely by 1 minute filament; spine at tip of stem. Long 6th joint with short medial bristle with base close to dorsal margin. 7th joint: a-bristle short, about same length as bristle of 6th joint, with few marginal spines; b-bristle stout, about twice length of a-bristle, with 2 marginal filaments and spine at tip; c-bristle very long with about 12 marginal filaments, each with 2 spines at tip. 8th joint: d- and e-bristles bare with blunt tips, about one-third longer than b-bristle; f-bristle similar to c-bristle; g-bristle with 2 short filaments and spine at tip, about same length as d-bristle.

Second Antenna (Figure 14e,f): Protopodite bare. Endopodite 3-jointed: 1st joint short with 5 small bristles (4 proximal, 1 distal); 2nd joint elongate with 2 ventral bristles; 3rd joint reflexed on 2nd, with 1 short proximal bristle and 2 short slender subterminal bristles; tip of 3rd joint with ridges (Figure 14e,f). Exopodite (Figure 14e): 1st joint long with ventral spines and minute terminal midbristle with blunt tip; 2nd joint small, with bare bristle reaching just past distal end of long 3rd joint; bristles of joints 3–8 with natatory hairs, no spines; 9th joint with 4 long bristles with natatory hairs and 1 minute bare bristle; distal margins of joints 3–8 with lateral spines forming row; distal margin of short 2nd joint with about 4 long stout lateral spines and many shorter lateral spines.

Mandible (Figure 14g): Coxale endite consisting of small tooth with 2 minute bristles near base. Basale: medial side near ventral margin with 3 proximal bristles (1 long, 2 short) followed by 2 medium-length bristles and then 1 or 2 longer bristles; spines forming rows present on medial surface; dorsal margin with 3 bristles. Exopodite elongate, hirsute (no bristles observed). 1st endopodial joint with medial hairs and 2 ventral bristles. 2nd endopodial joint: dorsal margin with 4 proximal bristles; ventral margin with short spines forming rows and 6 distal bristles; medial surface with hairs forming rows. 3rd endopodial joint with 1 long clawlike bristle with faint spines along ventral margin, and 4 short slender ringed bristles.

Maxilla (Figure 14h): Limb reduced. Bristles of 3 endites difficult to discern accurately. Coxale with hirsute dorsal bristle (broken off on illustrated appendage). Basale with spinous dorsal bristle and 1 ventral bristle. Exopodite with 3 spinous bristles (2 long, 1 short). 1st endopodial joint with slender bare alpha-bristle and long stout hirsute beta-bristle. 2nd endopodial joint with 6 or 7 bristles.

Fifth Limb (Figure 14i): Reduced. Endite I with 3 bare bristles; endite II with 4 bare bristles; endite III with 6 faint bristles. 1st expodial joint with 2 bristles and 3 or 4 weakly developed teeth. 2nd joint with several bristles and weakly developed teeth. Inner lobe of 3rd joint obscure but with at least 2 bristles; outer lobe of 3rd joint with 2 long hirsute bristles. Fused 4th and 5th joints with total of 4 bristles.

Sixth Limb (Figure 14j): 2 short bristles in place of epipodial appendage. Endite I with 3 short bristles; endite II with 2 bristles; endite III with 1 short bristle and 1 or 2 long bristles; endite IV with 2 or 3 bristles. End joint with 2 anterior bristles with short marginal spines followed by 1 bristle with long proximal and short distal spines, and 3 stouter hirsute bristles.

Seventh Limb (Figure 14k): Each limb with 4 distal bristles (2 on each side) and 4 proximal bristles (2 on each side); each bristle with up to 5 bells and marginal spines. Terminus consisting of comb with 3 spinous teeth opposing comb with 2 spinous teeth.

Furca (Figure 14l): Each lamella with 3 strong claws followed by 3 very weak claws.

Bellonci Organ: Elongate, distal part broken off on specimen examined (Figure 14m).

Eyes (Figure 14m): Medial eye with brown pigment and minute dorsal process. Lateral eye with dark pigment and about 22 ommatidia (exact number difficult to determine because of dark pigment; illustrated lateral eye shows only edges of a few ommatidia).

Posterior of Body: Similar to that of female.