Spondylus exiguus Lamprell & Healy, 2001
LAMPRELL, K. L. & J. M. HEALY. 2001. Spondylidae (Bivalvia) from New Caledonia and adjacent waters. Mémoires du Muséum National d’Histoire Naturelle, 185: 111-163 (In: P. Bouchet & B. A. Marshall Eds., Tropical Deep-Sea Benthos 22). [p. 117, figs. 2C-2J]
2001 Spondylus exiguus Lamprell & Healy, 2001
K. L. Lamprell & J. M. Healy, 2001, figure 2.
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«TYPE MATERIAL. — Holotype and 7 paratypes MNHN.
TYPE LOCALITY. — New Caledonia, Barrier reef South of Nouméa, Grotte Merlet, 22°40.2' S, 166°37.9' 8,20-35 m [LAGON, sta.1374].
MATERIAL EXAMINED. — New Caledonia. LAGON: sta. 521, Lagon Nord, 19°05' S, 163°38' E, 39 m, 1 lv. — sta. 830, off Poindimié, 20°49' S, 165°19', E, 105-110 m, 121 lv, 22 rv (paratypes) Sta. 1314, Grotte Merlet, 22°40.2' S, 166°37.9' E, 20-35 m, 4 pv (holotype Figs 2 C-D and paratypes Figs E-I), 59 lv, 9 rv.
EXPÉDITION MONTROUZIER: sta. 1249, Passe de Touho, 20°49' S, 165°19' E, 80- 140 m, 2 lv. — Sta. 1261, Chenal de Touho, 20°46'-20"47 ' S, 65°15'-165°-16.5' E,45-56 m, 1 lv, 1 rv. — Sta. 1275, Passe de Touho, 20°49' S, 165°17' E, 50-62 m, 15 lv, 1 rv. — Sta. 1311, Passe de Koumac, tombant Est, 20°40.4' S, 164°14.9' E, 10-60 m, 1rv (paratype). — Sta. 1319, Passe Deverd , 20°44.7' S, 164°15.5' E, 1 5-20 m, 1 lv. — Sta. 1323, Chenal de la Passe de Koumac, 20°40.9' S, 164°14.8' E, 82-120 m, 3 lv (paratypes). — Sta. 1331, Grand Récif de Koumac, 20°40'-20°40.6' S, 164°11.2'-164°12.1' E, 55-57 m, 8 lv, 1 rv. BATHUS 1: sta. DW692, 20°35' S, 164°59' E, 140-150 m, 1 lv. — Sta. DW1236, 21°20' S, 165°54', E, 60 m, 1 lv. DISTRIBUTION. — Known only from New Caledonia. Alive in dimly lit cave in the barrier reef, in 20-35 m; separate valves in sediment on outer slope of barrier reef to 140 m. Because of its small size and cryptic habitat, this species may have been unrecognized elsewhere and have a broader distribution.
DESCRIPTION. — Shell height to 6.4 mm (rv paratype from sta. 1311), pear-shaped, moderately solid, almost equivalve, rv slightly more convex than lv, auricles comparatively small, umbo prominent, pointed terminally. Lv sculpture of 35-40 strong, flattened, radial ribs crossed by dense, ventrally imbricated, angulate, concentric lamellae; the interstices are narrow and are also crossed by the concentric lamellae; internally moderately excavated under hinge plate; margin strongly crenulate. Rv convex, deeper than lv; sculpture similar to lv; attachment area small; margin evenly crenulate. Prodissoconch ovoid, 160 μm in length, with sculpture of fine concentric ribs. Colour white, yellow or orange internally and externally.
Measurements of holotype: Height 3.6 mm, width 3.4 mm, depth of pv 1.7 mm. REMARKS. — The shell sculpture is very distinctive in having very narrow interstices with wide ribs ornamented by dense, imbricating scale-like angulate spines. To our knowledge no other known species exhibits a similar sculpture. S. exiguus appears to be the smallest known Spondylus species, the largest specimen examined measures 6.4 mm from umbo to ventral margin. It can best be compared with S. proneri sp. nov., S. gussonii Costa, 1829 (Fig. 5 H) and S. ostreoides Smith, 1885 but differs principally in its very small size and distinctive ribbing and spine structure. For comparisons between S. exiguus and those species, see Table 3.
ETYMOLOGY. — Latin exiguus (adj.), small.»
KEVIN LESLIE LAMPRELL & JOHN M. HEALY, 2001
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«Diagnosis. Shell small, (up to 9.2 mm in height) pear-shaped, moderately solid, and nearly equivalve; auricles relatively small. Sculpture consisting of 35-40 pronounced, flattened, scabrous radial ribs; spines are scale-like and angulated; interstices narrow. Color variable from uniformly cream to orange and yellow.
Remarks. The EI and SyG material is identical in shape and sculpture to Spondylus exiguus. However, at least two specimens are in excess of 9 mm and thus represent new maximum size for this small species. Habitat. Commonly found at many locations around EI, in sand and rubble, from 30–80 m. Distribution. Spondylus exiguus was originally described from New Caledonia, but is also known from Easter Island. It has never been recorded from the Hawaiian Islands, New Zealand or the Kermadec Islands.» RAINES, B. K. & M. HUBER. 2012. Biodiversity Quadrupled—Revision of Easter Island and Salas y Gómez Bivalves. Zootaxa, 3217: 1-106, figs. 1-49. [p. 38]
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Spondylus exiguus Lamprell & Healy, 2001; B. K. Raines & M. Huber, 2012, Biodiversity Quadrupled—Revision of Easter Island and Salas y Gómez Bivalves, figures 18A, 18B.
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