File:American malacological bulletin (1988) (18129827306).jpg

Title: American malacological bulletin
Identifier: americanmal6719881990amer (find matches)
Year: 1983 (1980s)
Authors: American Malacological Union
Subjects: Mollusks; Mollusks
Publisher: (Hattiesburg, Miss. ?) : (American Malacological Union)
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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116 AMER. MALAC. BULL. 6(1) (1988)
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Fig. 1. Map of Oman and the Arabian Gulf. beach, are frequently exposed at low tide (maximum tidal range ca. ± 1.5 m). A narrow band of clean sand about 20 m from shore can also be exposed during extreme low tides. Further offshore the substratum is composed of loose rock with some weed and algae cover, coral debris, small pieces of live coral and fine sand. Seaward, small patches of live coral occur on soft sand that becomes gravelly sand near coral heads. An extensive coral reef is located ca. 200 m from shore at a depth of 5 m. Chitons are found in the loose rock zone about 30-75 m from shore, usually on undersides of rocks or dead coral where the water depth rarely exceeds 1 m. Temperature is very high in the shallows, though in winter it drops below 11°C. This gives an annual temperature differen- tial of ca. 30°C. Wakrah is a small town south of Doha (Fig. 1: no. 11) with very wide sandy beaches backed by limestone ridges. In the extreme shallows near the beach broken fasht lies on top of shelly gravel and sand. Hard packed, fine, white, ex- posed sand bars are located about 50 m from the beach and extend to ca. 200-300 m from the shoreline. These are ex- posed at low tide. Following a slight drop-off into 1-1.5 m depths, there first occurs a band of fine white sand, then loose rock and dead coral covered by algae and weed. A second fine white sand area occurs beyond the first and is followed by another band of shell and coral debris and loose algae and weed covered rocks that rise to ca. 30 cm in height. Here chitons were occasionally found on the undersides of rocks. Chitons were also found on shells of Pinna muricata L. The chitons live on the parts of the shells which are deeply buried in the sand. Chitons were never found on the broken fasht. The temperature is high, ca. 2°C less than that at Ras Abruk; the salinity is possibly higher. Las Hatte (= Al Ashat), situated offshore from Umm Said (Fig. 1: no. 12), consists of a group of four small limestone islands with sandy beaches fringed by live coral about 75 m from shore where a fairly steep drop-off occurs. Chitons (= Lepidozona luzonica (Sowerby, 1842)) are found on dead valves of arkshells (Arcidae) from about 10 m down to the seabed at about 25-28 m. The substratum comprises a mix- ture of silty black mud and sponges. Salinity is ca. 40-50 ppt at the surface and increases with depth. The water temperature in summer is lower than at other locations, rare- ly exceeding 36°C; temperature in winter is ca. 12-15°C due to greater water depth. The following abbreviations are used throughout the text: BG, Private collection of B. Glayzer; BMNH, British Museum (Natural History), London; FH, Private collection of F. Hinkle; KS, Private collection of K. Smythe; MCZ, Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts; MNHN, Museum National d'Histoire Naturelle, Paris; RMNH K, Private collection of P. Kaas, now in Rijksmuseum van Natuurlijke Historie, Leiden; VB, Private collection of R. Van Belle; ZMHU, Zoologisches Museum an der Humboldt Universitat, Berlin. SYSTEMATIC ACCOUNTS Class Polyplacophora Order Neoloricata Suborder Ischnochitonina Family Ischnochitonidae Dall, 1889 Subfamily Ischnochitoninae Genus Ischochiton Gray, 1847 Type Species: Chiton textilis Gray, 1828 (by subsequent designation, Gray, 1847). Subgenus Ischnochiton s.s. Ischnochiton (I.) yerburyi (E. A. Smith, 1891) Figs. 2-7 Chiton (Ischnochiton) yerburyi E. A. Smith, 1891: 420, pi. 33: fig. 6. Ischnochiton yerburyi, Pilsbry, 1892: 101, pi. 20: fig. 11. Nier- strasz, 1905: 30. Thiele, 1910: 111, 113. Kaas, 1954: 5. Leloup, 1960: 35, fig. 5. Biggs, 1973: 374. Leloup, 1980: 10. Smythe, 1982: 83, fig. 17. Ferreira, 1983: 251, figs. 1, 2. Glayzer ef al., 1984: 324. Kaas, 1986: 11, figs. 8, 8a, b (synonymy). (?) Ischnochiton rufopunctatus Odhner, 1919: 21, pi. 3: figs. 40, 41. (?) Ischnochiton (Radsiella) delagoaensis Ashby, 1931: 40, pi. 6: figs. 63-66. Ischnochiton haersoltei Kaas, 1954: 5, figs. 7-9.

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