Scintilla Deshayes, 1856

Oliver, P. Graham & Holmes, Anna, 2004, Cryptic bivalves with descriptions of new species from the Rodrigues lagoon, Journal of Natural History 38 (23), pp. 3175-3227 : 3198-3199

Genus Scintilla Deshayes, 1856

Type species: Scintilla philippinensis Deshayes, 1856 .

Scintilla pisum Sowerby, 1862

( figures 85 , 93 , 95 )

Scintilla pisum Sowerby, 1862: 178 , pl. 235, figures 54, 55 .

Material examined. Two specimens (one in alcohol, the other dry) from southern channel ( figure 85 ), NMW.Z.2001.061.00025; one and one (gold-coated) specimens from Totor, NMW.Z.2001.061.00026.

Description. Shell to 8.5 mm in length, solid, opaque. Moderately tumid. Not gaping. Equivalve. Subequilateral with beaks just forward of the midline, outline elliptical with broadly rounded anterior and posterior margins, the posterior slightly wider, the anterior a little truncated. Beaks protruding above dorsal margins. Sculpture of fine concentric lines. Hinge ( figure 93 ) prominent with peglike teeth. Right valve with a single large tooth below the beak, anterior to it a broad socket and at the top of the socket a minute tubercular tooth. A gap containing the internal backwards projecting resilium separates the anterior teeth from the posterior, which consist of a single laminar peg with a shallow socket behind. Left valve with a low tooth below the beak and a larger anterior tooth bounded by sockets, posterior tooth large bounded by shallow sockets. Ligament mostly internal but a weak external ligament is present over the cardinal area. Shell colour a vivid lemon yellow both internal and external.

The mantle ( figure 95 ) can extend over all but the umbonal area and is sparsely tuberculate. The anterior inner mantle extends considerably to form an anterior cowl (terminology from Mikkelsen and Bieler, 1992) but there is no corresponding posterior extension. There is a pair of low stubby tentacles situated dorsal of the posterior exhalant siphonal opening, but these were not observed to extend beyond the shell margin. The mantle and all the tubercles and tentacle are white.

Habitat. Living animals were taken from holes and crevices of coral rubble on the reef front and slope. There was no apparent commensal association with other invertebrates.

Figures

FIGS. 81–88. (81) Scintilla lynchi, NMW.Z.2000.086.00011 [8.98 mm]. (82) Scintilla vitrea, NMW.Z.2000.086.00004 [7.37 mm]. (83) Scintilla larcombei, NMW.Z.2001.061.00028 [3.29 mm]. (84) Scintilla anomala, NMW.Z.2000.086.00007 [9.2mm]. (85) Scintilla pisum, NMW.Z.2001.061.00025 [8.5 mm]. (86) Amphilepida aurantia, NMW.Z.1999.073.00004 [10.1 mm]. (87) Scintilla sp. A, NMW.Z.2000.086.00012 [2.62 mm]. (88) Scintilla sp. B, NMW.Z.2000.086.00013 [14.91 mm]. All external (MontageTM).

FIGS. 89–94. (89) Scintilla larcombei, NMW.Z.2001.061.00028. (90) Scintilla lynchi, NMW.Z.2000.086.00011. (91), Scintilla anomala, NMW.Z.2000.086.00007. (92) Scintilla vitrea, NMW.Z.2000.086.00004. (93) Scintilla pisum, NMW.Z.2001.061. 00025. (94) Amphilepida aurantia, NMW.Z.1999.073.00004. All hinge views (SEM).

FIGS. 95–98. Line drawings of live Scintilla showing tentacles. (95) S. pisum, NMW.Z.2001.061.00025. (96) S. anomala, NMW.Z.2000.086.00007. (97) S. lynchi, NMW.Z.2000.086.00011. (98) S. vitrea, NMW.Z.2000.086.00004.

FIGS. 53–59. Rhomboidiella rodriguesensis n. sp. (53, 54) Holotype, NMW.Z.2000.086.00001: (53) external (MontageTM); (54) external (SEM). (55–59) Paratype, NMW.Z.2000. 086.00002: (55) juvenile (MontageTM); (56, 57) juvenile (SEM); (58, 59) prodissoconch (SEM).