File:American malacological bulletin (1988) (18157448491).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 111
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146 147 148 149 Figs. 146-149. Cryptoconchus floridanus (Dall, 1889). Fig. 146. Whole specimen, 12.4 mm; Vaca Key, Monroe County, Florida; FSBC I 32081. Fig. 147. Whole specimen, 10.7 mm; same lot. Fig. 148. Jugum, valves iii-iv, same specimen as 147 (field width = 940 ^m). Fig. 149. Rudimen- tary pustules bordering jugum; same specimen as 147 (field width = 175 (im). valves ii-vii narrow, straight-sided for about 60% of length, thereafter expanded to truncate distal end, slightly elevated at central posterior beaks; valve viii narrow, straight-sided, with small, expanded, bulb-like terminus at low mucro. Tegmen- tum virtually absent on valves, only occasionally represented by few ovate, elongate pustules up to 80 long, 50 wide arranged parallel to jugal bars (Figs. 148, 149). Girdle smooth, appearing granulose or warty under magnification; 18 anterior and sutural dorsal pores situated as in other Acanthochitonidae, bearing about 10 extremely slender, fine-tipped spicules up to 100 ^m long; spicules at peripheral margin sparse, short (40 ^m), with blunt tips; under- side densely covered with short (70-80 ^m), sharp-tipped spicules. DISCUSSION: Pilsbry (1893) described the disarticulated valves of Cryptoconchus floridanus as white, pink or purple; the intermediate valves are rectangular, with a sinus before and behind; there are 5 anterior slits on valve i, single slits on the sides of valves ii-vii, and 2 posterior slits on valve viii. Specimens examined herein, when viewed through the fleshy underside, generally agreed with the standard 5-1-2 slit for- mula. However, the largest specimen (FSBC I 32081) has 6 unevenly spaced slits on valve i. Tegmental pustules have not been described for C. floridanus, but rudimentary pustules sometimes do occur on valves where the girdle does not ex- tend flush with the margin of the jugum. The Florida range of Cryptoconchus floridanus has not been extended since Dall's (1889b) original description of specimens from Cape Florida, Key Largo, Key West, and Dry Tortugas. The species occurs throughout the Bahama Islands and Greater Antilles, including Puerto Rico, Cuba (Jaume and Sarasua, 1943), Jamaica (Humfrey, 1975), and the Cayman Islands (Abbott, 1958). In the southern Caribbean, C. floridanus has been reported from Aruba and Bonaire (Kaas, 1972). The species has not been reported in the western Carib- bean from Mexico to Colombia. DISCUSSION More specimens must be examined before definitive conclusions can be made on the composition and relation- ships of the Acanthochitonidae of the Caribbean region. Of the 14 recognized species, only Cryptoconchus floridanus has not been involved in long-term or recent taxonomic confusion. Thus, nearly all published records must be considered ques- tionable, and the specimens upon which those records were based must be re-examined. In addition, more collections of Acanthochitonidae need to be made in the Lesser Antilles and along the Caribbean coasts of Central and South America. I examined far more material from Florida and the northern Caribbean region than from the southern Caribbean. That im- balance also occurs in published literature and probably will be found in the unreported museum collections. To my knowledge, there is no published record of any polyplaco- phoran from the area between Roatan, Honduras, and Limon, Costa Rica, yet that area contains the vast, shallow Honduras- Nicaragua shelf which exceeds in size the Bahama Banks. Given those cautions, some observations on the Caribbean Sea Acanthochitonidae seem warranted. Occurrence of species may be limited by distributional barriers, habitat availability, and environmental stress near the northern boundary of the Caribbean region. Only Acan- thochitona pygmaea occurs at Bermuda. In fact, only six of

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