Data from: Angelfishes, paper tigers and the devilish taxonomy of the Centropyge flavissima complex

The pygmy angelfishes (genus Centropyge) provide numerous examples of discordance between color morphology, taxonomy and evolutionary genetic lineages. This discordance is especially evident in the Centropyge flavissima complex, which includes three primary color morphs, three previously recognized species (C. flavissima, C. eibli and C. vrolikii) and three distinct mitochondrial (mtDNA) lineages that do not align with species designations. Our previous research showed that the putative C. flavissima arose independently in the Indian and Pacific Oceans, and the three mtDNA lineages align with geography rather than species assignments. Here we add 157 specimens to the previous dataset of 291 specimens, spread across a greater geographic range, to pinpoint the distribution of mtDNA lineages and color morphs. We found that the mtDNA lineages show remarkably strong geographic boundaries corresponding to the Indian Ocean, Central-West Pacific and Central-South Pacific. We also test the validity of the ‘Black Tiger Centropyge’ in the C. flavissima species complex, a taxonomic oddity that is restricted to shoals and atolls off the coast of northwestern Australia, and the newly named C. cocosensis (Shen et al. sp. nov. 2016) assigned to the C. flavissima lineage in the Indian Ocean. We conclude that the Black Tiger Centropyge is not a valid species but an intermediate between sympatric color morphs that correspond to the putative species C. eibli and C. vrolikii. Our greater sampling effort also do not support the genetic distinctiveness of C. cocosensis given shared mtDNA haplotypes with the sympatric C. eibli and C. vrolikii, but instead we find conflicting lines of evidence concerning the taxonomy of this group. We urge caution and taxonomic restraint until the true nature of this species complex can be revealed.

侏儒神仙鱼（Centropyge属）存在大量体色形态、分类学与演化遗传支系之间不一致的案例。这种不一致在黄刺尻鱼（Centropyge flavissima）复合群中尤为显著。该复合群包含三种主要体色形态、三种此前被认定的物种（黄刺尻鱼（C. flavissima）、艾氏刺尻鱼（C. eibli）以及沃氏刺尻鱼（C. vrolikii）），以及三个与物种定名不符的独立线粒体（mtDNA）支系。

我们此前的研究表明，被推定的黄刺尻鱼在印度洋与太平洋中独立起源，且三个线粒体支系的分布与地理区域相关，而非与物种定名对应。本研究在原有291份标本的数据集基础上新增157份标本，采样覆盖更广的地理范围，以精准定位线粒体支系与体色形态的分布情况。研究发现，线粒体支系呈现出极强的地理分界特征，分别对应印度洋、中西太平洋以及中南太平洋区域。

本研究同时验证了黄刺尻鱼复合群中的“黑虎刺尻鱼”的分类有效性——该类群为仅分布于澳大利亚西北近岸沙洲与环礁海域的分类学特殊类群，同时验证了2016年由Shen等人发表的新种科科斯刺尻鱼（C. cocosensis），该新种曾被归入印度洋区域的黄刺尻鱼支系。

本研究得出结论：黑虎刺尻鱼并非有效物种，而是对应于被推定物种艾氏刺尻鱼与沃氏刺尻鱼的同域体色形态之间的过渡类群。鉴于科科斯刺尻鱼与同域分布的艾氏刺尻鱼和沃氏刺尻鱼共享线粒体DNA单倍型，本研究扩大的采样规模同样不支持科科斯刺尻鱼具有遗传独立性；但与此同时，我们发现该类群的分类学证据存在矛盾。我们呼吁在明确该物种复合群的真实本质之前，应保持谨慎的分类学处理态度。