Eusarsiella cresseyi Kornicker 1986

Eusarsiella cresseyi

ETYMOLOGY.—The species is named for Roger Cressey of the Smithsonian Institution.

HOLOTYPE.—USNM 151990, ovigerous female, length 1.02 mm, whole specimen in alcohol.

TYPE-LOCALITY.—Placida Harbor, branch of Charlotte Harbor, off Bird Key, Florida, sample 3, 1 May 1974.

ALLOTYPE.—USNM 150282, adult male from same sample as holotype.

PARATYPES.—Placida Harbor: USNM 150100, 1 adult male, USNM 152303, 2 specimens, USNM 151991, 1 ovigerous female and 6 juveniles, USNM 151993, 12 specimens, from same sample as holotype: USNM 151994, 1 juvenile valve from sample 4. Anclote Anchorage: USNM 157431, 1 specimen, sta 6; USNM 157459, 1 adult male, USNM 157487, 1 specimen, sta 14; USNM 157109, 1 specimen, sta 30. Alligator Harbor: USNM 149314, 1 ovigerous female, sta I, 5–2. Corpus Christi ship canal, Texas: 1 juvenile, sta SR4.

DISTRIBUTION.—Florida: Placida Harbor, Anclote Anchorage, Alligator Harbor; Corpus Christi ship canal, Texas (Figure 4). Depth 0.75–3 m (Table 1).

DESCRIPTION OF FEMALE (Figures 88–90; Plates 26, 27).—Carapace oval in lateral view with projecting caudal process but without incisur.

Ornamentation (Figure 88; Plate 26): Carapace with U-shaped rib paralleling valve edge on anterior part of valve; rib slightly lower and more narrow at its anterior extremity dividing the rib into an upper and lower part, the latter being the longer of the two; 2 additional ribs present on each valve, one paralleling the posterodorsal valve edge, the other paralleling the posteroventral valve edge dorsal to the caudal process; all ribs consisting of long, closely spaced bristles with digitate tips; shorter bristles densely distributed over valve surface; long bristles with broad bases present along anterior and ventral margins of valves and on caudal process, and also scattered on lateral surface; transparent substance apparently filling spaces between long bristles forming ribs; ovoid bare, flat fossae with thin low rims widely distributed over valve surface but more clearly seen in the area of central muscle scar attachments (Plate 26a,b,j).

Infold (Figure 88a–c; Plate 27): Anterior infold slightly below valve middle with minute bristle near inner margin; posterior infold with 2 plumose bristles dorsal to caudal process; caudal process with 19–24 bristles; a few minute bristles present along inner margin of infold just anterior to caudal process.

Selvage (Figure 89b,c; Plate 27b,d): Wide lamellar prolongation with smooth margin present along anterior, ventral and posterior margins, and at tip of caudal process.

Size: USNM 149314, length 1.00 mm, height with caudal process 0.87 mm, height without caudal process 0.76 mm; USNM 151990 (holotype), length 1.02 mm, height with caudal process 0.95 mm, height without caudal process 0.82; USNM 151991, length 1.00 mm, height with caudal process 1.00 mm, height without caudal process 0.85 mm.

First Antenna (Figure 89d, 90d): First joint bare. Second joint with spines along dorsal and ventral margins and on medial surface, and 1 bristle on distal dorsal margin. Third and fourth joints fused; third joint short with 1 ventral and 1 dorsal bristle, neither reaching distal end of fourth joint; fourth joint with one terminal short dorsal bristle and 2 long terminal ventral bristles, both with very faint marginal spines; spines forming clusters present on dorsal margin and medial surface of fourth joint. Sensory bristle of fifth joint with 2 minute marginal filaments. Sixth joint with small terminal medial bristle. Seventh joint; a-bristle about twice length of bristle on sixth joint; b-bristle short, slender, about 3 times length of a-bristle, c-bristle about same length as sensory bristle, with 1 or 2 minute marginal filaments. Eighth joint: d- and e-bristles bare, slightly shorter than sensory bristle; f- and g- bristles about same length as sensory bristle, with 1 or 2 minute marginal filaments. (Marginal filaments extremely small and exact number uncertain.)

Second Antenna (Figure 89e: Protopodite bare, without medial bristle. Endopodite 1-jointed with 1 short bare proximal bristle and 1 long spinous terminal bristle. Exopodite: first joint with clusters of long hairs along ventral margin and with small recurved medial terminal bristle; bristle of second joint reaching well past end of limb and with small slender ventral spines proximally and natatory hairs distally; ninth joint with only 2 bristles, 1 long with natatory hairs, 1 short, bare; joints 2–4 with short spines forming row along terminal margin; bristles of joints 3 and 4 with ventral spines proximally and natatory hairs distally along both margins and proximally along dorsal margin; bristle of joint 4 with natatory hairs proximal to few marginal spines on ventral margin proximal to middle; bristles of joints 5–8 with natatory hairs.

Mandible (Figure 89f): Coxale with hairs along ventral margin and on lateral side near dorsal margin, and small endite on medial side near ventral margin. Basale: dorsal margin with very faint subterminal spine; ventral margin with 5 short bristles (3 of these forming group on medial surface). No exopodite present. Endopodite: first joint with slightly rippled dorsal margin with slender subterminal spines forming row extending onto medial surface, ventral margin with short faint medial bristle at base of main claw; medial surface of joint with short stout spines forming distal group; main claw with 3 or 4 minute teeth proximally on dorsal margin; second joint with minute dorsal bristle and smooth main ventral claw; third joint with 2 minute ventral bristles near base of main claw; ventral margin of main claw with 3 or 4 minute proximal teeth.

Maxilla (Figure 89g): Coxale with short anterior bristle and hirsute epipodial appendage. Endites with total of about 12 bristles including 2 on margin of endite I. Protopodite with transparent thumb-like process near base of endite I. Basale with 1 short bristle close to exopodite. Exopodite with 2 bristles, inner bristle about one-half length of outer bristle. Endopodite: first joint with alpha- and beta-bristle with proximal marginal teeth and distal marginal hairs or slender spines; second joint with 2 lateral a-bristles, 1 medial c-bristle, and 5 stout pectinate terminal bristles.

Fifth Limb (Figure 89h): Epipodial appendage with 28 bristles; single endite present with 1 short bristle. Exopodite: first joint with 2 bristles with faint marginal spines; second to fifth joint fused; second joint with 2 spinous bristles of equal length; third to fifth joints with total of 3 bristles; exopodite with hairs along outer margin.

Sixth Limb (Figure 89i): Endite I with 2 short bristles; end joint with 9 slender bristles (bare or with short marginal spines) separated by short gap from 2 stout hirsute posterior bristles; limb with long hairs on posterior half.

Seventh Limb (Figure 89j, 90a, b): Each limb with 8 bristles, 2 proximal, 1 on each side, and 6 terminal, 3 on each side; each bristle with 2–5 bells and no distal marginal spines; proximal bristles and 2 of the terminal bristles short; terminus with opposing combs, each with 5 to 7 teeth; a minute but distinct spine present in center of terminus between combs.

Furca (Figure 90c): Each lamella with 5 claws followed by several small spines; claw 1 continuous with lamella, others separated from lamella by suture; claws 1–3 with teeth forming lateral and medial row along posterior margin; claws 4 and 5 with single row of teeth along posterior margin; claws 2–5 with hairs along anterior margin; medial hairs present at base of claws and following claw 5.

Bellonci Organ (Figure 90d,e): One-jointed, elongate, broadening distally, with rounded tip.

Eyes (Figure 90d, e): Lateral eye small with about 5 minute ommatidia; medial eye bare, larger than lateral eye.

Upper Lip (Figure 90d): Helmet shaped without hairs or spines.

Posterior of Body: Small spines forming clusters on lateral and medial surfaces of vestment proximal to furca visible at high magnification (× 1000).

Anterior of Body (Figure 90d): Triangular process present between medial eye and upper lip.

Brush-like Organ (Figure 90f): Consisting of about 7 minute bristles anterior to Y-sclerite and proximal to genitalia.

Genitalia (Figure 90g): Oval spermatophore present on USNM 149314.

Y-Sclerite (Figure 90h): Normal for family.

Eggs: USNM 149314 with 7 eggs in marsupium.

Gut Content: USNM 149314 with juvenile copepod in gut.

DESCRIPTION OF ADULT MALE (Figures 91–93).—Carapace with projecting rostrum and with caudal process projecting posteriorly; smaller than female (Figure 91).

Ornamentation (Figure 91): Flat oval fossae on valves more distinct than on female; upper rib extending from rostrum to posterodorsal knob but discontinuous near middle of valve; lower rib extending from rostrum near incisur to point near middle of posterior margin where rib curves upward to form posterior knob which lies below and posterior to posterodorsal knob; upper and lower ribs may be continuous between posterodorsal and posterior knobs but are not connected on rostrum.

Infold: Similar to that on female except only 11 or 12 bristles on infold of caudal process.

Selvage: Similar to that of female.

Size: USNM 150282, length 0.80 mm, height 0.54 mm; USNM 150100, length 0.82 mm, height 0.62 mm.

First Antenna (Figure 92a): First joint bare, second joint with spines forming short rows on medial surface near dorsal margin and with 1 dorsal bristle with tip not reaching distal end of fourth joint. Third and fourth joints fused; third joint with short slender dorsal bristle and minute ventral bristle; fourth joint with 1 short dorsal bristle and 2 subequal ventral bristles. Sensory bristle of small fifth joint with numerous filaments on basal part and 3 or 4 short filaments near middle. Sixth joint with short medial bristle. Seventh joint: a-bristle about the length of sensory bristle; b-bristle with short triangular base, slender, slightly longer than a-bristle; c-bristle slightly shorter than sensory bristle, with 2 short marginal filaments. Eighth joint: d- and e-bristles bare, about same length as c-bristle; f- and g-bristles about same length as c-bristle, with 2 short marginal filaments.

Second Antenna (Figure 92b,c): Protopodite bare, without medial bristle. Endopodite 1-jointed with short proximal bristle and slightly longer terminal bristle. Exopodite: first joint with hairs proximally along ventral margin and minute medial spine; distribution of spines and natatory hairs on bristles of joints 1–9 shown in Figure 92c; ninth joint with 2 bristles; joints 2–6 and probably 7 with spines forming row along distal margin.

Mandible (Figure 93a): Ventral margin of coxale bare; small endite present. Basale: dorsal margin with 1 fairly long subterminal bristle; ventral margin with short proximal bristle; medial side with 3 short bristles forming group near ventral margin and 1 knife-like bristle dorsal to group of 3 bristles; lateral side with 1 minute bristle near proximal ventral margin. Exopodite consisting of small transparent process with abundant long hairs. Endopodite: first joint hirsute along dorsal margin and with slender spines forming row at middle of medial surface, and with 3 ventral bristles, 2 short, 1 long, stout; second joint with spines forming row on medial side near distal margin, and 2 bristles, 1 near middle of dorsal margin, 1 terminal on ventral margin; end joint with stout terminal claw and 3 small bristles, 1 dorsal, 2 ventral.

Maxilla (Figure 93b): Limb smaller than that of female, bristles weakly developed; anterior margin of coxale with short bristle; exopodite with 2 long bristles; first joint of endopodite with alpha- and beta-bristle; bristles of end joint weakly developed.

Fifth Limb (Figure 93c): Epipodial appendage with 26 bristles. Endite I with 1 short bristle. Exopodite, first joint with 2 bristles; second to fifth joints fused, with total of 5 bristles; long hairs present along outer side of exopodite.

Sixth Limb (Figure 93d): Endite I with 2 or 3 short bristles; end joint with 2 or 3 bristles with bases on medial side near ventral margin and 8 broader bristles along ventral margin; the former bristles with long proximal hairs and short distal spines, the latter bristles with only long hairs; limb hirsute.

Seventh Limb (Figure 93e): Minute, vestigal.

Furca: Distribution and number of claws similar to those of female furca.

Bellonci Organ (Figure 93f): Similar to that of female.

Eyes (Figure 93g,h): Lateral eye about same size as medial eye, larger than that of female, with 5 or 6 ommatidia; medial eye similar to that of female.

Upper Lip: Similar to that of female.

Copulatory Organ (Figure 93i): Complex clasping organs hanging down at each side. Each clasper consisting of 3 lobes with few short bristles; main lobe terminating in sclerotized hook and proximal tooth near base of inner curvature.

Y-Sclerite: Similar to that of female.

COMPARISONS.—The new species, E. cresseyi, is much smaller than E. tubipora (Darby, 1965), and also differs from that species in having only 1 instead of 2 proximal bristles on the endopodite of the second antenna. The carapace of E. cresseyi differs from that of E. ozothothrix Kornicker and Bowen (1976:497) in that the upper horizontal rib is divided into 2 parts.