Milneria kelseyi
| Milneria kelseyi | ||||||||||||
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| Scientific name | ||||||||||||
| Milneria kelseyi | ||||||||||||
| Dall , 1916 |
Milneria kelseyi is a shell - type from the family of trapeze shells (Carditidae).
features
The equally flared, strongly inflated housing is small and measures up to 17 mm in length. It is approximately trapezoidal in outline and strongly elongated to the rear. It is therefore strongly unequal, with the straight curled (orthogyratous) vertebrae well in front of the midline. The ratio given is: length = 11 mm, height = 3 mm and thickness or diameter = 4.5 mm. The posterior dorsal margin is almost straight and rises sharply (ventral margin as a horizontal reference line). It merges with the very broad, slightly arched rear edge at a flat, rounded angle. The anterior dorsal margin is very short, slightly arched and slopes almost vertically. Only a slight change in angle can be seen between the dorsal edge and the anterior edge. The anterior margin merges into the ventral margin in a tightly rounded manner. The ventral margin is curved straight to slightly concave in the males. In females, the ventral side is sunk like a bubble in the rear half of the housing. The ventral margin (of the right and left valves) is therefore strongly sinuous. The lunula is small and narrow. The area is large and wide, and clearly delimited. The lock has a triangular or, better described, lambda-shaped main tooth or two diverging main teeth in the left flap. There are three main teeth in the right valve, of which the anterior and posterior main teeth are very small. Posterior teeth are absent, with the exception of a very small posterior posterior tooth in the left flap. The ligament sits behind the vertebra. There are two sphincter muscles of approximately the same size. The surface line is entire.
The light brown skin is thick and firm. A strong keel pulls from the vertebra to the lower rear edge of the case. The ornamentation consists of 6 to 10 weak radial ribs that intersect with somewhat irregular, very closely spaced ribs parallel to the edge. The ribs parallel to the edge are widened scaly. The crossing points can be reinforced with knots. The inner edge of the case is finely notched. The inside of the shell is whitish to pale beige in color.
Similar species
Milneria kelseyi is very similar to the other species in the genus Milneria , Milneria minima (Dall, 1871). The latter species is smaller and it lacks the clear keel, which in Milneria kelseyi runs from the vertebra to the lower rear end. In Milneria minima the lunula is relatively large and clearly sunk, the area is narrow and small. In Milneria kelseyi , the lunula is very small, but the area is larger and clearly defined.
Geographical distribution and habitat
The range extends from Monterey Bay ( California , United States, 36.6 ° N) to Punta Pequeña, Baja California (26.2 ° N) and in the Gulf of California in Bahía de los Ángeles (State of Baja California , Mexico, 28.9 ° N).
The species occurs from the intertidal zone to about 37 meters water depth. She builds nests between stones with byssus threads.
development
The species is segregated. Up to 50 young mussels were found in a special “brood pouch” or “marsupium” on the ventral side and outside the case, which were attached with byssus threads in this indentation of the case. According to one opinion, the “brood pouch” or the “marsupium” should be closed with periostracum, and according to another opinion with a fold of the mantle.
How the young mussels get into this indentation has not yet been observed. However, they can only come into the indentation or attach themselves there after the byssus gland is fully developed. In analogy to other species of the Carditidae family with brood care, the larvae develop between the gills in the mantle cavity and then settle for a certain time in the indentation on the ventral side of the mother animal.
Taxonomy
The species was founded in 1916 by William Healey Dall . It is widely recognized as a valid species. An illustration can be found in The Light and Smith Manual: intertidal invertebrates from Central California to Oregon.
supporting documents
literature
- Eugene Victor Coan: Is there double trouble in marsupial clams. The Veliger, 17 (2): 183-184, 1972 online at www.biodiversitylibrary.org
- Eugene Victor Coan: Preliminary Review of the Northwest American Carditidae. The Veliger, 19 (4): 375–386, 1977 PDF (online at ResearchGate)
- Eugene Victor Coan, Paul Valentich-Scott: Bivalve Seashells of Tropical West America marine Bivalve mollusks from Baja California to Northern Perú. Part 1,598 pp., Santa Barbara Museum of Natural History, Santa Barbara 2012 ISBN 978-0-936494-43-2 (p. 385)
- Edouard Lamy: Review of the Carditacea vivants du Muséum National d'Histoire Naturelle de Paris. Journal de Conchyliologie, 66: 218–276, 289–368, 1922 Online at www.biodiversitylibrary.org (p. 353)
Individual evidence
- ^ A b William Healey Dall: Diagnoses of new species of marine bivalve mollusks from the Northwest Coast of America in the collection of the United States National Museum. Proceedings of the United States National Museum, 52: 393-417, Washington 1916 (December 27) Online at www.biodiversitylibrary.org First description p. 408
- ^ A b Charles M. Yonge: Functional morphology and evolution within the Carditacea (Bivalvia). Proceedings of the Malacological Society of London, 38: 493-, London 1969, doi : 10.1093 / oxfordjournals.mollus.a065067
- ^ R. Tucker Abbott: American seashells. With photographs by Frederick M. Bayer. XIV, 541 pp., Van Nostrand, Toronto et al. a., 1954 Online at www.biodiversitylibrary.org (p. 381)
- ^ William Healey Dall: Synopsis of the Carditacea and of the American Species. Proceedings of the Academy of Natural Sciences of Philadelphia, 54: 696-716, Philadelphia 1902. Online at www.biodiversitylibrary.org (p. 701)
- ↑ MolluscaBase: Milneria kelseyi Dall, 1916
- ^ Carlton, James T. (Eds.): The Light and Smith Manual: intertidal invertebrates from Central California to Oregon. 4th fully revised and enlarged edition, XVII, 1140 pp., Berkeley, Calif., University of California Press, 2007 ISBN 0-520-23939-3 , 978-0-520-23939-5 Preview on Google Books (image)