Huysentruyt Frank, Brunain Marleen, Adriaens Dominique
Evolutionary Morphology of Vertebrates, Ghent University-UGent, K L Ledeganckstraat 35, 9000 Gent, Belgium.
J Morphol. 2008 May;269(5):522-32. doi: 10.1002/jmor.10603.
Callichthyids take a basal position in the loricarioid evolutionary lineage leading up to an algae scraping feeding mechanism in the loricariid family. Therefore, the study of the morphology and development of a callichthyid representative would contribute to a better knowledge on the differences in cranial morphology and their impact on feeding ecology within this superfamily. Therefore, development in the chondrocranium of Corydoras aeneus was studied based on 22 cleared and stained specimens and 6 series of serial sections. The latter sections were also digitized and used for 3D reconstructions. Development overall follows the typical siluriform trends in chondrocranial development. Even the low complexity of the chondrocranium at hatching fits the trend observed in other siluriforms, although other studies showed loricarioid hatchlings to generally show more complex chondrocrania. In contrast to other catfish, in C. aeneus, the notochord was never found to protrude into the hypophyseal fenestra. In addition, also differing from other siluriforms, a commissura lateralis is present, a state also reported for Ancistrus cf. triradiatus (Geerinckx et al., [2005] J Morphol 266:331-355). The splanchnocranium again has the typical siluriform shape during its ontogeny, with the presence of a compound hyosymplectic-pterygoquadrate plate, although not fused to the neurocranium or interhyal at any time during ontogeny, a state described earlier for Callichthys callichthys (Hoedeman, [1960a] Bull Aquat Biol 1:73-84; Howes and Teugels, [1989] J Zool Lond 219:441-456). The most striking difference found in comparison to other catfishes, however, involves thebranchial basket, which arises as a single element with a further differentiation from the middle arches on in both a rostral and caudal direction.
甲鲶科鱼类在骨甲鲶科进化谱系中处于基部位置，该谱系最终进化出骨甲鲶科的刮食藻类取食机制。因此，对一种甲鲶科代表性鱼类的形态学和发育进行研究，将有助于更好地了解这个超科内颅骨形态的差异及其对取食生态学的影响。因此，基于22个透明和染色标本以及6组连续切片，对青铜鼠鱼（Corydoras aeneus）软骨颅的发育进行了研究。后面这些切片也进行了数字化处理并用于三维重建。总体发育过程遵循典型的鲶形目软骨颅发育趋势。即使孵化时软骨颅的复杂性较低，也符合在其他鲶形目中观察到的趋势，尽管其他研究表明骨甲鲶科幼体的软骨颅通常更为复杂。与其他鲶鱼不同的是，在青铜鼠鱼中，从未发现脊索突入垂体窗。此外，同样与其他鲶形目不同的是，存在外侧连合，这种状态在似三辐下口鲶（Ancistrus cf. triradiatus）中也有报道（Geerinckx等人，[2005年]《形态学杂志》266:331 - 355）。脏颅在个体发育过程中再次呈现典型的鲶形目形状，有一个复合的舌颌骨 - 翼方骨板，尽管在个体发育的任何时候都未与脑颅或间舌骨融合，这种状态之前在美丽甲鲶（Callichthys callichthys）中有过描述（Hoedeman，[1960a年]《水生生物学通报》1:73 - 84；Howes和Teugels，[1989年]《伦敦动物学杂志》219:441 - 456）。然而，与其他鲶鱼相比，最显著的差异涉及鳃篮，它作为一个单一元素出现，并从中间鳃弓开始在吻部和尾部方向进一步分化。
