Page 156 - 《水产学报》2026年第2期

2 期 PASSMORE Roland Madziva，等：银灰半棱鳀仔稚鱼的脊柱和附肢骨骼发育 50 卷

ence and the environmental conditions that, in turn,
Sn
influence the genetic regulation of bone formation,
Na which varies among species [37-39] .
Uroneural 1 appears to fuse with the preural
centrum 1 to form a pleurostyle. The presence of a
pleurostyle is well recorded in clupeoid fishes [27, 29] .
0.25 mm 1 However, its presence in ostarioclupeomorphs and
some euteleosts is yet to be clarified, and extensive
Na
[40]
research is needed in different teleostean subgroups .
Sn
Since the skeletal elements forming the pleurostyle
differ among different fish groups, the structure is not
homologous but rather a different morphological char-
acteristic [34-35] , and this poses a difficulty in its defini-
0.25 mm Pa 2 tion. In E. punctifer, epurals initially appeared as sep-
arate structures, but later, Ep1 and Ep2 fused forming
an anterior-dorsal compound epural. A compound
[30]
Sn epural has been reported in E. japonicus and in other
[31]
clupeoid species such as Sprattus sprattus .
Ns
However, the number of epurals varies among Clupei-
[19]
formes members. For instance, in C. harengus , only
1.00 mm 3 2 epurals form and such fusions have not been docu-

mented.
Plate Ⅶ Abdominal portion of the vertebral column,
[30]
Like other clupeoid species, such as E. japonicus ,
showing the development of supraneurals
(1) 14.73 mm SL; (2) 18.08 mm NL; (3) 34.46 mm SL. Pa. Parapo- opisthural cartilage is also present in the caudal fin of
physis; Sn. supraneural. E. punctifer (present study). A comparative study
revealed that some osteological characters such as
Research shows that some clupeoid fishes pos-
shape and position of opisthural cartilage could be
sess a fusion of certain caudal elements, such as
used as a suitable feature for the identification of some
hypurals, although this characteristic is not univer-
[18]
clupeids at the species and genus levels . However,
sally observed within the family. The fusion of
[41]
in other Engraulidae species such as E. australis , the
hypural 2 with the first ural centrum occurs in Clupeo-
opisthural cartilage was not confirmed.
morpha [27,34-35] . In E. punctifer, hypural 2 was also
fused to ural centrum 1 (present study). There are no 3.2 Appendicular skeleton
other fusions of hypurals, except for a temporary car- In E. punctifer, proximal radials (pterygiophores
tilaginous bridge that connects hypural 1 and the par- in other descriptions) of the dorsal fin developed
hypural, which eventually separates once the car- anteriorly, and those of the anal fin exhibited bidirec-
tilaginous base of hypural 1 ossifies. Initially, tional development, thus from the first median prox-
uroneural 1 develops as cartilage. In contrast to our imal radial of the anal fin, then spreading both anteri-
findings, uroneural 1 is formed as bone in E. orly and posteriorly. Such is the case described in E.
[19]
[30]
[42]
[30]
japonicus , as in C. harengus . Caudal structural japonicus , Sardinops melanostictus , and Alosa
variations from one species to another are related to sapidissima , while in other clupeoid species, as in
[43]
the mode of adaptation to swimming as well as to the the descriptions of Fischbach et al. [19] , the formation
[36]
evolutionary status of the species . This difference of dorsal and anal fins was observed to take place in a
can be attributed to species-to-species habitat prefer- bilateral pattern, which is also common among teleost
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