Fairy wrasses are some of the most ubiquitous fishes in the marine aquarium trade, which is why it may come as a surprise to learn that the group has never received a serious taxonomic review. The scientific literature is filled with scattered species descriptions, but there is typically nothing more than a cursory sentence suggesting possible evolutionary relationships within the genus. And socirrhilabrus, despite being the most species rich of the wrasses, is very much a phylogenetic cipher. In an effort to fill this void, Lemon TYK and I will be presenting a series of articles covering this genus in all its baroque detail.
cirrhilabruscurrently stands at 49 described species, but this number is likely to be far lower than it should be—my best estimate is that there could potentially be greater than 60 distinct taxa. I use the word “taxa” because much of this argument centers on how we define the term “species”. The arbitrariness of its application within fairy wrasse classification has much to do with the current state of affairs. For instance, should a widespread and phenotypically diverse “species” like the Exquisite Wrasse (C.大型) be treated in the same manner as therubriventralis小组，其成员同样多样化，但分为多个“物种”，在整个印度洋中有单独的范围？显然，几乎没有任何争论来支持这种不一致的用法，因为这里唯一真正的区别可能是这两个分类单元的相对年龄。
Throughout the numerous species groups we can see a consistent pattern of biogeographic endemism. Species from the Red Sea are likely to have a nearly identical sister taxa along the East Coast of Africa and another in the Maldives. Moving eastward, the waters of the Andaman Sea, Western Sumatra and Java typically has its own species distinct from the rest of the “coral triangle”. This hints at some of the historical geography of the region, when lower sea levels and different oceanic currents limited dispersal between the Indian and Pacific Oceans. To this day, there is still only a small region centered on Bali where the different oceanic populations converge.
Examining the Pacific groups, we find a recurrent theme of speciation forming an arc of similar taxa from Japan, through Indonesia and New Guinea, and eastward into the Melanesian islands of Fiji, Tonga and Samoa. Again, we find inconsistencies in how taxa are treated. In some groups (lanceolatus/roseafascia或者lunatus/brunneus), Japanese and “coral triangle” populations are treated as separate species. In others (rubrimarginatus和Temminckii），一系列相关人群被视为单个分类单元。但是，为什么一个群体比另一个人更值得呢？这迫使我们解决生物学中最烦人的问题之一：什么定义了一个物种？
当然这里没有简单的答案。然而we choose to define our species concept, exceptions will occur. If we look at a group like the fairy wrasses, we see a series of presumably isolated populations which share genes amongst themselves by interbreeding, and which are likely to have limited genetic exchange with neighboring populations. This is the classic model of allopatric speciation. But this raises an important question, how long must two populations be in isolation before speciation can be said to occur? Should the various populations ofTemminckiibe treated as a single species based on the assumption that this taxon is young and hasn’t been isolated enough for “true species” to have formed? There is simply no data to confirm this one way or the other.
And what about species with wide ranges and limited phenotypic differences? The various populations ofrubrimarginatushave little to recommend them as distinct taxa, but presumably there is genetic regionalism here waiting to be discovered. How much genetic divergence would be required to split this single species into its three major subpopulations? Is a 2% difference in its genetic code enough? How about 1%? Is it enough to say that populations with limited interbreeding are separate species even if the DNA is identical?
Sympatric speciation, which is the creation of new species within the same geographic range, seems to be a rare phenomenon incirrhilabrus。这两个最明显的例子的研究很少，并且有些有争议。cirrhilabrusbrunneus和the undescribed “cflunatus两者都在印度尼西亚和菲律宾重叠的范围中发现，但是这两者都是从相对较少的标本中知道的，因此可能事实证明，这些样本只是一个物种的性别不同。还有什么cirrhilabruslubbocki和flavidorsalis, another pair with completely overlapping ranges? There are already two color forms oflubbocki，不能flavidorsalisbe a third? Without any published research on whether these variants interbreed or what genetic divergence can be found here, how are we to know if there is a single heterochromatic taxon, three sympatric species or the status quo of two “species”? And then there isC. condei, which may have an allopatric sister species in Fiji and a sympatric species in New Guinea. To summarise the current state of affairs, confusion reigns.
虽然我们可能还没有在物种水平上坚定地掌握，但研究物种群体之间的关系似乎更为直接。本文中介绍的系统发育树是我知道的第一个全面处理，但是主要的限制是，它基于着色和身体形状的相似之处。形态学上，cirrhilabrusshows little differentiation. Commonly used characters like fin counts, scale counts and gill counts show a confusing amount of overlap. Juvenile coloration is often diagnostic within a species group, but seems less informative between them. While I expect much of this tree to stand up to more serious study, there are almost certainly erroneous relationships here. Fortunately, several researchers are studying this group’s genetics, and it is only a matter of time before a proper study appears. Until then, you’ll have to make do with this preliminary effort.
关于这棵树优点讨论的几点。有三个主要的谱系：一个是Lubbocki组的基础分支，而其他两个谱系可以除以骨盆鳍的相对大小，以及在婚礼显示过程中尾鳍闪烁的趋势。后一个字符在Temminckii和rubriventralis/filamentosus在展示过程中，可以将整个尾鳍变成反射蓝或金。除了蓝囊该谱系中的所有主要物种组的组也至少有一个物种，在婚姻雄性的前背鳍下面有一个浅色的腰带。
A few groups are particularly difficult to place into a coherent phylogeny. Most troublesome is thelubbocki小组的形态和模式（尤其是未修剪的女性）似乎有足够的不同，以暗示其基础位置，但可以同样属于其他骨盆鳍短的群体。一些作者建议与C。Bathyphilus，但是头部形状和身体模式的差异似乎反对这一点。这Bathyphilus团体is also of uncertain placement, as it seems best diagnosed by a lack of characters rather than the presence of its own unique apomorphies. Its isolated range suggests it may be a phylogenetic relic, but perhaps more species in this deep-dwelling group await discovery.
然后是cirrhilabruslaboutei，其奇异的肛门鳍扩展和异常圆形的尾鳍表明了高度孤立的谱系。实际上，我的初始树利用这些差异将其视为最大的进化枝，但是身体模式的巨大相似之处与诸如C.大型和C. lunatusultimately led me to include it alongside them. An alternative would be to regard the prominent dorsal and medial stripes as ancestral in the genus, with groups likelubbocki和Bathyphilusbeing derived, miniaturized taxa which have lost this ancestral feature. This may in fact be a more parsimonious way of looking at things, but only genetic study can clear this matter up.
Future articles in this series will focus on each of the species groups, of which there are around eleven. That is to say, this has been no small undertaking. Rather than my dry taxonomic drivel, you’ll have the pleasure of being guided through this genus’ immense diversity by the flowery prose of Lemon TYK. Hopefully we can do justice to the fascinating story these fishes have to tell…
Photography credits for the collage photo include Kevin Kohen, Hiroyuki Tanaka, Rudie H. Kuiter, Gerry Allen, John Randall and Kazu.
