Illinois Natural History Survey - University of Illinois

Anodontites irisans Marshall, 1926

A. irisans USNM 359920

USNM 359920. Holotype. Venezuela.

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Original Description: Anodontites irisans Marshall, W.B. 1926. New land and fresh-water mollusks from Central and South America. Proceedings of the United States National Museum. 69(12):1-12 + 3 plates.

Type Locality: Venezuela.

Holotype: USNM 359920.

Possible Paratypes: CAS 64885. Marshall (1926) examined and sent back one the of the five shells in the lot from Stanford (now CAS 64885) without a specific indication of which one it was so the paratype in the lot cannot be determined.

Synonymy:

  • Anodontites irisans Marshall, 1926
  • Marshall 1930:7; Baker, 1930:68.
  • Anodontites (Anodontitiespatagonicus leotaudi (Guppy, 1864)

  • Haas 1966:567.
  • Anodontites (Anodontitiesleotaudi (Guppy, 1866) (in part)

  • Johnson 1981:281.
  • Description: "Shell elongate-oblong, compressed, rather thick, rounded and narrower in front, truncately rounded, wider and somewhat nasute behind; dorsal margin lightly arcuate, making an indistinct, very obtuse angle with the posterior margin and rounding into the anterior margin. Ventral margin nearly straight, sloping gently upward toward and fading into the anterior margin without any angle. Anterior area descending rapindly from the body of the shell without a ridge; posterior area gently sloping, the posterior dorsal ridge low and rounded. Posterior dorsal area with a faint rib running from the beak to just above the posterior ventral angle. Surface nearly smooth but with many fine concentric growth lines and a few heavier lines marking rest periods of growth. Anteriorly and posteriorly the fine growth lines are more prominent, forming fine lamellae. To the unaided eye there are faint indications of radiating striae. With a fairly high power microscope the periostracum shows innumerable rediating threads. Color chestnut brown throughout. Interior brilliantly pearly, very iridescent along the anterior, posterior, and ventral portions and especially in the adductor scars. General color of interior bluish. Anterior adductor scar moderately deep posterior scar nearly superficial; prismatic margin very narrow and of a dark olive color. Pallial line very feebly marked, about 8 mm. from the margin.

    The type, Cat. No. 359920, USNM, measures: Length, 70 mm.; height, 39 mm.; diameter, 32 mm. It comes from Venezuela and was received from Mrs. T. S. Oldroyd, of Leland Stanford University, to whom a paratype was returned.

    Except for the differences in the character of the hinge this shell in both internal and external features as almost an exact counterpart of specimens of the common Elliptio complanatus of the United States. Its nearest relative is Anodontites leotaudi Guppy, which comes from the island if Trinidad." (Marshall, 1926:10-11).

    Specimens Examined: USNM 359920 (1). Venezuela. Mrs. Oldroyd. CAS 64885 (5). Venezuela, R. Arnold.

    Literature Cited



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