Morphology of larvae of the family Mytilidae (Bivalvia) from the north-western part of the Sea of Japan

Abstract

The larval shell morphology of 10 bivalve species of the family Mytilidae (Adula falcatoides, Crenella decussata, Crenomytilus grayanus, Modiolus kurilensis, Musculista senhousia, Mytilus coruscus, Mytilus galloprovincialis, Mytilus trossulus and Septifer keenae, and an unidentified species Mytilidae indeterminate) from the Sea of Japan is described. The following morphological features were comparatively examined: larval shell outlines including shape and size of umbones, and anterior, posterior and ventral margins, hinge morphology, ligament location, sculpture, colour, and eye-spot outlines. Some dimensional parameters of larval shells are given. The time interval of occurrence of larvae in the plankton, water temperature in this period, and shell length of competent larvae are presented. It is demonstrated that, in spite of sometimes similar external morphological characters, identification of mytilid larvae creates no difficulties if all distinguishing characters are used.

Functional morphology, biology and sexual strategy of the circumboreal, adventitious crypt-building,Crenella decussata(Bivalvia: Mytiloidea: Crenellidae)

“…Figure 3B is another, higher magnification SEM photograph of the umbonal region of the adult, dissoconch, shell showing the initially slightly nodular but subsequently smooth prodissoconch I and II and the progressively reticulated patterning of the late nepioconch and the dissoconch. Similarly, the SEM photomicrographs of larval and early post-metamorphic shell stages of Crenella decussata from Vostok Bay (Sea of Japan) provided by Semenikhina et al (2008) and Kolotukhina et al (2011) showed only three clearly delineated shell stages, that is, a prodissoconch, and nepioconch and a dissoconch, and with a surface patterning similar to our findings. These authors also believed that in Vostok Bay, C. decussata had a short pelagic stage prior to metamorphosis, although this could not be verified by their employed sampling strategy.…”

Morphological structures of the shell of Mytilus trossulus and Crenomytilus grayanus in early ontogenesis and their importance in the taxonomy of Mytilinae (Bivalvia: Mytilidae)

“…Our data on the morphogenesis of early stages of M. trossulus and Crenomytilus grayanus (Dunker, 1853), along with previous studies of other species of Mytilinae (Evseev et al , 2005; Semenikhina et al , 2008), expand the total number of characters of the subfamily and help to provide more detailed characterizations of its constituent taxa. The results obtained are useful, and yet a problem remains unsolved, especially what is the rank of the early stage features; in other words whether they would be applied to a taxonomic system of the adults as a species or genus, subfamily and family.…”

“…These morphological peculiarities primarily concerning the general outlines of larval shell, its umbo, number of relatively uniform teeth of the provinculum and topology of the primary ligament pit are discriminating characters of larvae of other taxa of the subfamily as well, among them Mytilaster lineatus (Gmelin, 1790) (Zakhvatkina, 1972), Choromytilus chorus Molina 1782 and Mytilus chilensis Hupe 1854 (Ramorino & Campos, 1983), Ischadium recurvum (Rafinesque, 1820) (Fuller & Lutz, 1989), Mytilus californianus Conrad 1837 (Martel et al , 2000) and Perna viridis (L. 1758) (Hanyu et al , 2001). An exception may be larvae of Septifer keenae Nomura 1936 (Figure 5H), whose shell, in contrast to that of other taxa of the subfamily, consists of a D-shaped prodissoconch I (PD-I) (Evseev et al , 2004, 2005; Semenikhina et al , 2008).…”

Early Stages in Morphogenesis of the Shell of Crenella decussata (Bivalvia: Mytilidae)

“…Larvae of C. decussata distinctly differ from other mytilid larvae by a D-shaped shell, absence of umbo, the straight hinge margin, and homogeneous fine-grained sculpture without co-marginal lines of growth (Semenikhina et al, 2008 Adams, 1862) are rounded, but their nepioconchs lack radial ribs (Evseev et al, 2007).…”

“…Larvae were also identified based on the descriptions of larval morphology of mytilid species available in the literature (Jørgensen, 1946;Rees, 1950;Chanley & Andrews, 1971;Le Pennec & Masson, 1976;Booth, 1977;Lutz & Hidu, 1979;Le Pennec, 1980;Redfearn et al, 1986;Fuller & Lutz, 1989;Kasyanov et al, 1998Malchus, 2006;Semenikhina et al, 2008;Evseev et al, 2010). Larval shell terminology is the same as in the foregoing works.…”