Kk. Holden et Mn. Bruton, THE EARLY ONTOGENY OF THE SOUTHERN MOUTHBROODER, PSEUDOCRENILABRUS PHILANDER (PISCES, CICHLIDAE), Environmental biology of fishes, 41(1-4), 1994, pp. 311-329
The early development of the southern mouthbrooder, Pseudocrenilabrus
philander, is documented from activation until the early stages of the
juvenile period. The duration of the embryonic period is about 14 day
s at 25 degrees C. Development is direct and there is accelerated exog
enous feeding into the embryonic period. The pattern of development an
d the timing of ontogenetic events and structure formation are a refle
ction of both internal and external environmental conditions. During m
outhbrooding, oxygen uptake is facilitated by embryonic respiratory pl
exuses and flapping of the pectoral fins. At the time of first release
from the buccal cavity, the embryos are in an advanced state of devel
opment. The switch-over from the temporary embryonic respiratory syste
m to the adult branchial system has occurred. The yolksac serves as a
supplemental source of nutrition as the embryos develop their external
food-gathering abilities. The skeletal and sensory systems are suffic
iently developed to allow the young to return to the safety of the fem
ale's buccal cavity. Pigmentation may provide disruptive colouration.
The rate and pattern of development of another mouthbrooding cichlid,
Oreochromis mossambicus, is similar to that of P. philander despite th
eir phylogenetic differences, and may be a consequence of similar life
-history styles.