摘要：

The Veliger 33(3):241-271 (July 2, 1990) THE VELIGER © CMS, Inc., 1990 A Review of the Recent Eastern Pacific Acanthochitoninae (Mollusca: Polyplacophora: Cryptoplacidae) with the Description of a New Genus, Americhiton by G. THOMAS WATTERS The Museum of Zoology, The Ohio State University, Columbus, Ohio 43210, USA . Recent species of the Acanthochitoninae in the eastern Pacific are reviewed. Members of the genus Acanthochitona include: A. angelica Dall, 1919, A. avicula (Carpenter, 1864), A. exquisita (Pilsbry, 1893), A. jerreirai Lyons, 1988, A. hirudimformis hirudiniformis (Sowerby I, 1832), A. hirudi- niformis peruviana (Leloup, 1941), and A. imperatrix Watters, 1981. A new genus, Americhiton, is created for A. arragomtes (Carpenter, 1857), type species, and the western Atlantic species A. andersoni (Watters, 1981), A. balesae (Abbott, 1954), and A. zebra (Lyons, 1988). INTRODUCTION The family Cryptoplacidae, containing the two subfamilies Cryptoplacinae and Acanthochitoninae, includes diverse, predominantly tropical and subtropical chitons that have a confusing taxonomic history. Although this group is a significant component of most chiton faunas, the identifi- cation of even the most common species may be proble- matical. In recent years several attempts have been made to clarify the status of New World chitons including cryp- toplacids. Thorpe (1971) published an account of the eastern Pacific species and Kaas (1972) followed with Caribbean taxa. In 1980, I completed an unpublished Master's Thesis review of the family Cryptoplacidae in the New World utilizing scanning electron microscopy (SEM); my brief 1981 articles were extracted from that thesis. Ferreira (1985) published a study of the chitons of Barbados in which he reached several incongruous and unfortunate conclusions on the family Cryptoplacidae. Lyons (1988a) also reviewed the Caribbean species of this family using SEM, and described six new species (one, however, was from the eastern Pacific), and corrected much of the confusion instituted by Ferreira. This report, mod- ified from my 1980 thesis, covers the remaining eastern Pacific species. The results of this study indicate that eight species and subspecies of Cryptoplacidae occur in the Recent of the eastern Pacific. All belong to the subfamily Acanthochi- toninae (the Caribbean Choneplax lata (Guilding, 1829) is the only New World member of the Cryptoplacinae). The eastern Pacific taxa are as follows: Acanthochitona angelica Dall, 1919 Acanthochitona avicula (Carpenter, 1864) Acanthochitona exquisita (Pilsbry, 1893) Acanthochitona ferreirai Lyons, 1988 Acanthochitona hirudiniformis hirudiniformis (Sowerby I, 1832) Acanthochitona hirudiniformis peruviana (Leloup, 1941) Acanthochitona imperatrix Watters, 1981 Americhiton arragomtes (Carpenter, 1857), gen. nov. In strict accordance with ICZN rules (Art. 50 (a)), I have cited Pilsbry or Dall as the author of Carpenter's manuscript names where appropriate. Although this manuscript was the basis of much of their work on chitons, and its influence duly noted by subsequent workers, it was never published by Carpenter. Nevertheless, both authors gave credit to Carpenter for names and descriptions of taxa, and under ICZN Art. 50 (a), Carpenter could be considered the "some other person . . . alone responsible both for the name and for satisfying the criteria of avail- ability other than publication," and as such "then that person is the author of the name." Numerous workers have not resolved this problem to their satisfaction and have cited these species as "Carpenter in Dall" or "Car-

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