File:American malacological bulletin (1988) (18157444391).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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LYONS: CARIBBEAN ACANTHOCHITONIDAE 109 imately 85% of valve length. Valves ii-vii elongate (Fig. 131), strongly produced posteriorly to overhang following valves; tegmentum elongate, pentagonal, widest behind middle, with straight anterolateral margins; sutural laminae long, nearly in line with plane of valves, curving anteromedially from posterolateral corners of tegmentum, with subacute tips separated anteriorly by deep, U-shaped sinus; single, shallow, notch-like slits along lateral margins. Valve viii tegmentum pen- tagonal (Fig. 132), widest anteromesially, produced posteriorly, with mucro at posterodistal tip (Fig. 133); jugum absent; sutural laminae extending tooth-like from anterolateral margins of tegmentum; posterior insertion plate and slits absent. Tegmental morphology of small specimens varies con- siderably from that of larger specimens (Figs. 135-142). Valves of very large specimens usually so eroded that posterior edges are straight instead of pointed. Jugum of valves ii-vii smooth, relatively narrow, little
Text Appearing After Image:
Figs. 135-142. Choneplax lata (Guilding, 1829). Valves i-viii ex 6.7 mm juvenile; West End, Grand Bahama; FSBC I 32548. expanded anteriorly; jugum indistinct on valves of small specimens. Tegmentum of all valves covered evenly with coarse, spatulate pustules (Fig. 134) approximately 90 long, 50 /*m wide, generally flattened but with raised, central dome and adapical macresthete, few or no micresthetes. Girdle upper surface covered with small (100 /xm), densely packed, club-shaped spicules; anterior and sutural tufts poorly developed, comprised of about 18-22 short (to 1.0 mm), stout, smooth, sharp-tipped, reddish brown or some- times white spicules; marginal spicules 500 long, smooth, straight or slightly curved, white, rarely reddish brown; under- side covered with small (100 /xrm), straight, sharp-tipped, clear spicules. DISCUSSION: Choneplax lata is distinguished from all species of Acanthochitona by lacking slits on the posterior margin of valve viii (Figs. 143-145). Kaas (1972) and Ferreira (1985) discussed uncertainty regarding the number of slits on valve i and intermediate valves. The three specimens I dissected (6.7-30.0 mm) each had 5 distinct slits on valve i, not 3 as reported by Pilsbry (1893), and single, notch-like slits on intermediate valves. Based on the 5-slitted valve i, Choneplax is more similar to Acanthochitona than to Crypto- plax, which has 3 slits; however, Choneplax shares the unslit tail valve with Cryptoplax. Chiton strigatus Sowerby, 1840, has long been

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