Super black plumage is prevalent among <i>Lepidothrix</i> manakins

Super black plumage has been observed across the avian phylogeny, yet few studies have examined the prevalence of super black plumage at the species and subspecies levels. One group where additional super black taxa likely exist is manakins in the genus <i>Lepidothrix</i>. Previous work on these sexually dichromatic taxa showed that male <i>Lepidothrix velutina</i> (Velvety Manakins) have super black plumage, and we observed that males of several other <i>Lepidothrix</i> taxa have black plumage with a velvety appearance that is often associated with super black barbule morphologies. Here, we combine spectrophotometry with scanning electron microscopy to examine the occurrence of super black plumage throughout <i>Lepidothrix</i>. We determine how the barbules of super black taxa differ structurally from barbules of black taxa that lack super black plumage. Our results show that five species and seven subspecies of <i>Lepidothrix</i> have super black plumage, that barbules of back feathers are wider in super black taxa than in black taxa, and that the super black plumage trait appears to have evolved multiple times independently in the genus. We also show that olive green immature males of super black taxa exhibit wider barbules than their counterparts, suggesting the development of super black plumage begins before males molt into their definitive adult plumage.超黑羽毛（super black plumage）已在鸟类系统发育（avian phylogeny）的多个类群中被观测到，但目前鲜有研究在物种和亚种层面系统探讨其分布普遍性。侏儒鸟（manakins）中的丽侏儒鸟属（Lepidothrix）便是一类极可能存在更多未被发现的超黑类群的类群。 此前针对该性二态类群（sexually dichromatic taxa）的研究表明，雄性绒顶丽侏儒鸟（Lepidothrix velutina，Velvety Manakins）已被证实拥有超黑羽毛；而我们的观测显示，丽侏儒鸟属其他数个类群的雄性个体也长有带有天鹅绒质感的黑色羽毛，这类羽毛通常伴随超黑羽小枝（barbule）的特殊形态结构。 本研究结合分光光度法（spectrophotometry）与扫描电子显微镜（scanning electron microscopy）技术，对丽侏儒鸟属内所有类群的超黑羽毛出现情况开展了系统性探究。我们对比分析了超黑类群与非超黑黑色类群的羽小枝结构差异。 研究结果显示：丽侏儒鸟属共有5个物种与7个亚种拥有超黑羽毛；超黑类群背部羽毛的羽小枝宽度显著大于非超黑黑色类群；且超黑羽毛性状在该属内似乎独立演化了多次。 我们还发现，拥有超黑羽毛类群的橄榄绿色未成熟雄鸟，其羽小枝宽度大于同种成鸟，这暗示超黑羽毛的发育过程始于雄鸟蜕变为最终成鸟羽衣（definitive adult plumage）之前。