Page 157 - 《水产学报》2026年第2期

2 期 水 产 学 报 50 卷

fishes. In larger specimens of E. punctifer larvae and the stay bone originates from the last cartilaginous
juveniles (this study), the first proximal radial has an proximal radial. Observations by Kohno et al. [50] on
enlarged and forked anterior process. This structure Pagrus majo and on other species suggest that the stay
was previously thought to result from the fusion of at bone forms separate from the last pterygiophore, while
least two cartilage pieces in Clupeiformes [44-47] . On the in S. melanostictus, the posteriormost distal radial
[42]
[30]
contrary, our observations suggest that the formation gave rise to the stay bone . Similar to E. japonicus ,
of the anterior process of the first proximal radial is the stay bone in E. punctifer develops a different mor-
not due to the fusion of two proximal cartilages. phology and possesses an elongated process that
Instead, it appears to arise from the branching of the extends posteriorly.
first proximal radial. Also, observations for the Japan- In E. punctifer larvae, the cleithrum was the
ese anchovy suggested that the forked shape of the earliest structure to form as bone during skeletal onto-
first proximal radial (pterygiophore) is not a product of geny. The cleithrum is typically found in the pectoral
[48]
fusion but has its own developmental transfiguration . girdle of most teleost fishes, although variations in its
Furthermore, we observed the presence of a presence and morphology can occur among different
[51]
supernumerary distal radial (sdr) in the dorsal fin of E. species . In a hatchery‐ reared American shad,
[30]
punctifer, which aligns with findings in E. japonicus , Alosa sapidissima, the pectorals were the only fins that
[43]
where its presence was noted to be somewhat variable formed before the onset of feeding . In addition, our
during the early development of the dorsal fin sup- observations indicate that the propterygium might
ports. However, its presence raises different interpreta- have developed as a distinct structure. The connection
[30]
tions. According to Balart , if the fusion of the first between the first ray of the pectoral fin and the prop-
and second proximal radials is considered, the sdr may terygium has been documented in Clupeiformes, e.g.,
[30]
be interpreted as a radial of either the first or second E. japonicus and C. harengus [19] . However, its
proximal radials before they fuse to form a single large development and origin have raised various interpreta-
pterygiophore. In this case, the radial would not be tions. For example, studies by Balart [30,52] and Kohno et
[50]
considered a supernumerary element. In this study, al. suggested that the propterygium develops prior
[30]
like that for E. japonicus , such a fusion of the two to the detachment of the proximal radials. Another
proximal radial elements was not observed. Therefore, perspective is that the propterygium arises from blade
[30]
we conclude that the supernumerary radial develops cartilage in Clupeiformes . Notably, the postclei-
following the general sequence of chondrification, thrum is absent, as seen in other species of Engraul-
rather than developing after the other distal radial. idae [30,53] . In contrast, its presence was noted in clu-
[54]
[19]
Also, Balart interpreted the supernumerary radial a peids, such as C. harengus and Etrumeus micropus .
neoformation, probably related to the need for greater Pectoral fin structures such as the cleithrum were
mobility without restraining the anterior end of the observed at 3.78 mm NL, while the basipterygium of
[30]
dorsal fin . the pelvic fin were noted later at 11.91 to 12.89 mm
Another notable feature of the anal and dorsal SL. These findings align with patterns in other Clupei-
fins of E. punctifer is the stay bone (fin stay in other formes, where pelvic fin development is often
[30]
descriptions). It appears to originate from the posteri- observed at larger body sizes as noted in E. japonicus .
ormost proximal radials and remains separated by a Future studies with more comprehensive sampling are
cartilaginous band. In other clupeoid fishes, such as C. needed to clarify the developmental sequence of fins
[19]
harengus , the stay bone forms as cartilage independ- in E. punctifer. The significance of pelvic fins in tele-
ent of the last proximal radial and later fuses to it. Its osts has often been neglected, possibly due to their rel-
origin varies according to the descriptions of different atively small size and perceived functional unimport-
[55]
[49]
teleost taxa. Potthoff et al. stated that in swordfish, ance as discussed in past studies .
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