Parvamussium scutulatum Dijkstra & Maestrati, 2013
DIJKSTRA, H. H. & P. MAESTRATI. 2013. Pectinoidea (Bivalvia: Propeamussiidae, Entoliidae and Pectinidae) from the Tarava Seamounts, Society Islands and the Tuamotu Archipelago (French Polynesia). Zoosystema, 35 (3): 361-375, figs. 1-4. [p. 364, fig. 2]
2013 Parvamussium scutulatum Dijkstra & Maestrati, 2013
H. H. Dijkstra & P. Maestrati, 2013, figure 2.
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«TYPE MATERIAL. — Tarava Seamounts. Tarasoc, stn DW 3314, 19˚14’S, 151˚39’W, 803-815 m, paratypes 2 lv, 1 rv (MNHN 25700); stn DW 3328, 18˚46’S, 152˚15’W, 788-836 m, paratype 1 lv (MNHN 25701); stn DW 3333, 18˚45’S, 152˚18’W, 795-975 m, paratypes 3 lv, 4 rv (five MNHN 25702, two ZMA Moll. 398323); stn DW 3340, 18˚24’S, 154˚09’W, 787-792 m, paratypes 4 lv (MNHN 25703).
Society Islands. Tarasoc, stn DW 3421, 16˚46’S, 151˚04’W, 782-847 m, alive, holotype spm (MNHN 25699). Tuamotu Archipelago. Tarasoc, stn DW 3354, 15˚55’S, 147˚06’W, 860-1030 m, paratypes 1 lv, 1 rv (MNHN 25705). TYPE LOCALITY. — Society Islands, Huahine, 16˚46’S, 151˚04’W, 782-847 m (Tarasoc, stn DW 3421)
ETYMOLOGY. — Left valve with reticular sculpture (latin: scutulatus, adjective meaning with lozenge-shaped pattern).
DISTRIBUTION. — Society Islands and Tuamotu Archipelago, 782-1030 m, living in 782-847 m.
DESCRIPTION
Shell up to c. 5 mm in height, fragile, opaque to semi-transparent white, circular, inequivalve, left valve slightly more convex than right valve, almost equilateral, auricles subequal in shape and size, anterior demarcated from disc, posterior continuous with disc, umbonal angle c. 110˚. Prodissoconch 185 μm long. Left valve with reticulate sculpture of widely spaced commarginal and more closely spaced radial threads, commencing at 2 mm shell height, extending to ventral margin. Umbonal region glossy. Auricles with some closely spaced commarginal lamellate riblets near lateral margins. Right valve with regularly spaced commarginal lirae. Auricles with commarginal lamellae laterally, slightly stronger on anterior, more closely spaced on posterior. Hinge line straight. Byssal fasciole narrow. Each valve with 12 short internal riblets, commencing in late growth stage. External sculpture clearly visible from interior side. Resilifer triangular. Byssal notch moderately deep, ctenolium lacking. Dimensions of the holotype: H 4.7 mm, W 4.7 mm, D 0.9 mm. REMARKS
The present species is morphologically closest to Parvamussium multiliratum Dijkstra, 1995, known from the southwestern Pacific. The two species are similar in shape, but differ in size (Parvamussium scutulatum n. sp. up to c. 5 mm high, P. multiliratum up to c. 9 mm), in the sculpture on the left valve (P. scutulatum n. sp. reticular, P. multiliratum commarginal), and in the number of internal riblets (P. scutulatum n. sp. 12 short riblets, P. multiliratum 14 longer riblets plus one or two rudimentary).» HENK H. DIJKSTRA & PHILIPPE MAESTRATI, 2013
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