The functional morphology of Sinonovacula constricta with a discussion on the taxonomic status of the Novaculininae (Bivalvia).

Abstract

Sinonovacula constricta is representative of two genera of deep burrowing bivalves hitherto placed in the Novaculininae of the Tellinacea. This species, widely cultured in China, has not previously been critically examined. Aspects of its anatomy show that it should more properly be placed in the Solenacea. The presently accepted classification of this superfamily suggests that it should be placed close to Pharella in the Cultellidae but it is clear that the group requires more detailed re‐examination. Sinonovacula is somewhat posteriorly elongate with long separate siphons. The anterior pedal gape acts as a valve to the piston‐like foot enabling rapid reburrowing to occur. Sensory tentacles around the pedal gape respond to mechanical disturbance and water can be squirted from the gape to, presumably, flush away the source of irritation. Modifications of this kind are rare in the Bivalvia. The anatomy of Sinonovacula is described and related to its life style as a suspension feeder in soft intertidal muds. The ciliary currents of the mantle cavity are powerful, the labial palps in particular being large as compared with the relatively small ctenidia. The stomach is adapted for dealing with large amounts of food, though the sorting areas are not extensive; principal sorting is clearly the function of the labial palps. The style sac and mid‐gut are separate (unlike the conjoined style sac and mid gut of the Tellinacea), and ensure separation of the style from the sediment loaded mid gut. In many ways Sinonovacula foreshadows the highly modified true razor shells and conditions in these bivalves can be accounted for by further posterior elongation of a bivalve essentially similar to Sinonovacula.

Sperm ultrastructure in Hemidonax pictus (Hemidonacidae, Bivalvia, Mollusca): comparison with other heterodonts, especially Cardiidae, Donacidae and Crassatelloidea

“…In this connection it is worth noting that Pharus and the Novaculininae (both originally included in Solecurtidae) were often cited as tellinoidean taxa lacking a cruciform muscle (Yonge, 1949, 1959; Ponder et al ., 1981; Boss, 1982) but are now both placed within the Solenoidea (e.g. Morton, 1984; von Cosel, 1990; Willan, 1998).…”

The chromosomal-level genome assembly and comprehensive transcriptomes of Chinese razor clam (Sinonovacula constricta) with deep-burrowing life style and broad-range salinity adaptation

“…They play vital roles in the microtubule architecture 322 and the bending movement of cilia (Mohri et al, 2012). The razor clam has a 323well-developed ciliary system for gill filtering, food-particles retaining, and water 324 pumping(Morton, 1984). The adjoining cilia generate effective beat through 325 coordinated wavelike movements.…”

“…The pumping rate of the ciliary system in the gill326 and mantle cavity can be adjusted to generate powerful currents to facilitate the 327 principal sorting and retaining of suspended particles in the labial palps. Effluxes can 328 also be ejected from the pedal gape to flush away sources of irritation detected by the 329 sensory tentacles(Morton, 1984). The transcriptomic data revealed that the TUA and 330 DYH genes are highly expressed in the gills (Figure 3Band 3C), suggesting that the 331 expansion of these genes could be an adaptation to the deep-burrowing lifestyle.332 Phylogenetic inference of the 16 species was performed with the 337 single-copy 333 orthologs.…”

Shell Morphology and Sperm Ultrastructure ofSolen tehuelchusHanley, 1842 (Bivalvia: Solenidae): New Taxonomic Characters

“…Despite their economic importance, solenids are rarely investigated in comparison to other bivalve families, such as the Veneridae, Mytilidae and Ostreidae. While there have been some crucial studies on solenid biology and morphology (Ghosh 1920, Fraenkel 1927, Yonge 1952, Owen 1959, Morton 1989, Pohlo 1989 as well as on their systematics (Dall 1899, Lamy 1932, Cosel 1989, 1990, 1993, 2002 the taxonomy of these organisms, in particular, requires more detailed investigation.…”