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Chitons (Mollusca: Polyplacophora) - Biological Science - California ...

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Vol. XLI(6): 2009 THE FESTIVUS Page 61<br />

22. Central areas of intermediate valves appearing deeply pitted with longitudinal ridges distinctly cross-hatched;<br />

tegmentum with widely spaced digitate tubercles or closely set flat or slightly raised round tubercles; girdle scales<br />

only slightly convex with distinct longitudinal striations ................................23<br />

S<br />

Central areas not pitted, without distinct cross-hatching, although faint horizontal latticing may be apparent<br />

between the prominent longitudinal ridges; tegmental sculpture of closely set, button-like or globular to digitate<br />

tubercles, distance between tubercles about 1-2 times their width; girdle scales relatively large (>400 m),<br />

strongly convex, with or without weak striations, and crowned with a ribbed nipple (often broken off) ..24<br />

23. Tegmentum of end valves and lateral areas of intermediate valves sculptured with radiating rows of wellseparated,<br />

digitate tubercles, distance between tubercles at least several times their width; tegmentum and girdle<br />

coloration of banded reddish-browns and tans (color based on single specimen) ....... Lepidozona sp. A<br />

S<br />

Tegmentum of end valves and lateral areas sculptured with relatively flat or slightly raised, round, closely set<br />

tubercles, distance between tubercles about 1-2 times their width; tegmentum and girdle coloration mostly tan<br />

to light orange with perhaps a darker jugal ridge (color based on single specimen) ..... Lepidozona sp. B<br />

24. Head valve, lateral areas of intermediate valves, and posterior region of tail valve sculptured with rows of tall,<br />

globular to sometimes digitate tubercles; longitudinal ridges prominent throughout central areas, clearly<br />

extending across jugum; girdle scales typically smooth or with nearly obsolete longitudinal striations; color<br />

generally reddish-brown and blotched with lighter or darker tones ............. Lepidozona mertensii<br />

S<br />

Head valve, lateral areas, and posterior region of tail valve sculptured with rows of numerous, flattened, buttonlike<br />

tubercles; longitudinal ridges of central areas becoming faint or obsolete across the jugum; girdle scales<br />

usually with faint longitudinal striations apparent; color reddish-brown with white banding on some posterior<br />

valves (color based on single specimen) ................................. Lepidozona sp. C<br />

25. Girdle nude dorsally with microscopic elements appearing uniformly granular or sandy, without conspicuous<br />

spicules, spines, bristles, or hairs ..............................................26<br />

S<br />

Girdle with conspicuous dorsal spicules, spines, bristles, or hairs scattered variably over a more or less granular<br />

or sandy surface ..........................................................27<br />

26. Central areas of intermediate valves sculptured with 12-16 fine lateral riblets on each side, the<br />

remainder of the tegmentum evenly microgranulose; tegmentum color variable but mostly greens or reds<br />

...................................................... Dendrochiton gothicus<br />

S<br />

Tegmental sculpture smooth throughout; tegmentum color typically orange or pink, end valves and lateral<br />

areas with white zigzag lines, pleural areas with 2-5 large white flammules, although colors may be faint<br />

.......................................................... Tonicella venusta<br />

27. Girdle beset dorsally with spicules of different sizes and shapes or slender, hyaline spines, without conspicuous<br />

bristles or hairs ..........................................................28<br />

S Girdle beset dorsally with dendritic processes, bristles or flexible hairs .......................29<br />

28. Tegmentum sculptured with conspicuous, raised, spherical tubercles arranged in radiating, branching rows on<br />

head valve and lateral areas of the intermediate valves, and forming beaded lirae in central areas; girdle covered<br />

with spicules or spines of different types and sizes (smooth or ribbed, slender or thick, curved or straight);<br />

tegmental color usually orange, rarely green, often with tiny black pigment spots, tail valve often black and<br />

spotted with white ........................................... Chaetopleura gemma

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