. Bulletin. Science; Natural history; Natural history. 30Aj,m Fig. 2. Ischnochiton macleani, n. sp. Holotype. Radula: median, and first lateral teeth, and cusp of second (major) lateral tooth. (xlOOO). Articulamentum white: sutural laminae sharp, short, subquadrate. separated by well-formed sinus; insertion teeth neatly cut, somewhat thickened at edges, and followed by slit-rays; slit formula 8-1-8. Radula measures mm in length and mm in width, with 36 rows of mature teeth; median tooth (Fig. 2). wide anteriorly (30 /;), narrows medially (to 13 /^im) but becomes somewhat globose a
. Bulletin. Science; Natural history; Natural history. 30Aj,m Fig. 2. Ischnochiton macleani, n. sp. Holotype. Radula: median, and first lateral teeth, and cusp of second (major) lateral tooth. (xlOOO). Articulamentum white: sutural laminae sharp, short, subquadrate. separated by well-formed sinus; insertion teeth neatly cut, somewhat thickened at edges, and followed by slit-rays; slit formula 8-1-8. Radula measures mm in length and mm in width, with 36 rows of mature teeth; median tooth (Fig. 2). wide anteriorly (30 /;), narrows medially (to 13 /^im) but becomes somewhat globose at posterior end; first lateral tooth quadrangular with a thickened outer edge; second (major) lateral tooth has a tricuspid head on a thick (about 100 x 50 ixm) shaft; marginal (outermost) teeth are slightly longer (45 ju,m) than wide (38 ixm). Remarks.—Judging from the observed specimens, Ischnochiton macleani does not show much variation in tegmental sculpture. Most specimens have no spic- ulose fringe, but that may be due to the fragility of the longer spicules. Color varies from a uniform light brown or tan to two tones of brown, with the darker brown tones usually in the pleural areas. Banding of the girdle is present in only eight of 16 specimens. All specimens are small, but apparently mature. The largest specimen (Figs. lA. IB) measures mm in length, including the relatively wide ( mm) girdle; the smallest specimen in the type lot measures mm in length. The tegmental sculpture oiIschnochiton macleani is remarkably similar to that found in members of the genus Chaetopleiira Shuttleworth. 1853. However, the ischnoid articulamentum and the scaly girdle with no hairs or spicules (except for the marginal fringe) indicate that it belongs to the genus Ischnochiton Gray, 1847; the tegmental similarity to Chaetopleiira may be regarded as an example of evo- lutionary convergence. Ischnochiton macleani shows no obvious phylogenetic relationship to any one species of t
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