Cypridopsis vidua

Cypridopsis vidua (O. F. Müller), 1776

Cypris vidua O. F. Müller, 1776, p. 199.

Cypridopsis vidua (O. F. Müller), Brady, 1868a, p. 117.— Turner, 1892, p. 73.—Sharpe, 1918, p. 807, fig. 1253.— Hoff, 1942, pp. 151–153, pl. 8: figs. 115–117.—Kesling, 1951, pp. 2–116, plates—Swain, 1955, pp. 606–607, pl. 60: figs. 6a–c.—Benson, 1959, pp. 39–40, pl. 1: figs. 3a–b, pl. 8: fig. 8.—Gutentag and Benson, 1962, p. 26, fig. 6, p. 1: fig. 10.—Benson and MacDonald, 1963, p. 21, pl. 2: fig. 5.

Pionocypris vidua Brady and Norman, 1896, p. 726.

Cypridopsis vidua obesa Furtos, 1933, p. 431 [not Brady and Robertson, 1870, p. 15].

Cypridopsis pustulosa Furtos, 1933, pp. 431–432, pl. 6: figs. 5–9.

SIZE.—Right valve of adult: length 0.71 mm; height 0.47 mm. Left valve of adult: length 0.72 mm; height 0.46 mm.

MATERIAL.—Three specimens collected in bottom samples from Laguna Madre and 21 from Copano Bay.

OCCURRENCE.—The specimen illustrated is from Station 15 in Copano Bay, collection number 012659–1. This form was found only in Copano Bay (rare) and Laguna Madre (very rare). It was most abundant at Station 15 in February 1959. The distribution and scarcity of this form suggest that individuals may have been carried into the study area by streams. Swain (1955) reported this species in the Guadalupe River distributaries, and stated that it probably cannot withstand more than a trace of salinity.

TYPE-SPECIES.—Aglaia pulchella Brady, 1868b, p. 94, pl. 12: figs. 1, 2.

OCCURRENCE.—North Atlantic, tropics and sub-tropics; marine, shallow water.

Aglaiocypris? species

SHAPE.—Carapace elongate-subovate in lateral view; greatest height slightly anteromedially. Dorsal margin broadly arched, noticeably angulated in front of greatest height with angulation of right valve stronger than that of left; ventral margin nearly straight, very slightly concave medially. Anterior margin broadly and uniformly rounded, extended below, truncate above. Posterior margin considerably narrower, subacuminate and bluntly rounded; subtruncated above by dorsal margin at or slightly above midheight of valve. Carapace in dorsal view thin, elongate-ovate; greatest width somewhat anteromedially. Sides converging to very narrow, pointed ends, with posterior convergence more gradual than anterior.

ORNAMENTATION.—Absent; carapace completely smooth, transparent, and very delicate.

SIZE.—Right valve of adult: length 0.74 mm; height 0.34 mm. Left valve of adult: length 0.74 mm; height 0.34 mm.

INNER LAMELLA.—Moderately broad anteriorly and posteriorly; greatest width at the anterior, particularly anteroventrally. Line of concrescence and inner margin separated, forming a large anterior vestibule and somewhat smaller posterior and posteroventral vestibules. Inner lamella quite narrow along the ventral margin. List present near inner margin; weak submarginal selvage.

MARGINAL PORE CANALS.—Numerous, straight, very short, simple; most numerous (about 22) and closely spaced at the anterior margin, becoming more widely spaced along the ventral margin until resuming a closer spacing posteriorly (about 7).

HINGE.—Adont. Hinge structure not distinct or well developed but apparently consists of simple groove in left valve which receives dorsal margin of right valve.

NORMAL PORES.—Numerous, very small, scattered, open.

MUSCLE SCARS.—Consists of central cluster of 7 scars in addition to 2 anteroventral mandibular scars. The 7 closely spaced central scars are arranged as follows: a single clear, circular scar or fulcral point posterior to which is a slightly curving row of 4 elongate scars, and 2 irregular scars in horizontal row behind.

EYE SPOTS.—Absent.

OVERLAP.—Left and right valves nearly equal in size, but left valve slightly higher and overlapping right valve dorsally and ventrally.

SEXUAL DIMORPHISM.—Not apparent; width of inner lamella considerably less in some individuals than in others, but whether this is a sexual characteristic is not known.

MATERIAL.—In bottom samples 491 specimens collected from Redfish Bay, 12 from Laguna Madre, and 80 from Copano Bay.