The cyanopleura group is the next collection of fairy wrasses from the second major Cirrhilabrus clade (whose member taxa share the trait of mid-length pelvic fins) and is sister to the scottorum group. In the latter, certain traits that were diagnostic to the members will be more evidently presented in the various species here, suggesting the closeness between the two groups.
Members of this group are largely Pacific, with only three members straying very weakly into the Indian Ocean peripheries. This group is the most phylogenetically confusing of the Cirrhilabrus genus thus far, and with members that are so commonly encountered in the field and in the trade, you would think that more would be known about this group than any other.
Cirrhilabrus cyanopleura was the first of its kind to be discovered and described in the mid 18th century. Famed Dutch naturalist Pieter Bleeker first obtained a specimen from Indonesia in 1851 and proceeded to describe it as Cheilinoides cyanopleura. Two years later, in 1853, he described C. temminckii and C. solorensis from Japan and Indonesia respectively and placed them in a new genus, Cirrhilabrus. C. temminckii was then selected to be the type species representing this new genus. It was only then did Bleeker revise Cheilinoides cyanopleura and placed it alongside temminckii and solorensis in Cirrhilabrus, bringing the total number of species to three. Although C. temminckii remains as the type species, C. cyanopleura was technically the first fairy wrasse known to science.
Eleven years later in 1904, Ishigawa split Cirrhilabrus cyanopleura into two species based on differences in coloration. The split yielded Cirrhilabrus lyukyuensis, a species that is regarded by some to be nothing more than a color variant of C. cyanopleura. As the genus grew over the years, so did the cyanopleura group members, with Cirrhilabrus luteovittatus, C. randalli and C. aurantidorsalis being formally recognized, in 1988, 1995 and 1999 respectively. However, the original epithet for Ishigawa’s “lyukyuensis” was incorrect, and it was only in recent years was it amended to “ryukyuensis”, after the Ryukyu Islands of Japan.
Although C. cyanopleura and C. solorensis were some of the earliest known Cirrhilabrus, not much is known about their biology and phylogenetic proximity to the other species. To date, this group is shrouded in much taxonomic confusion and mystery. Information regarding the relationships between the known species is scant to say the least. In addition, there is an immense amount of variation and possible hybridization, as well as a couple of distinct regional variations which likely deserve species recognition.
The phylogenetic tree presented here is the first of its kind to tackle this intractable group, but the relationships are still not fully resolved. There are few (if any) morphological differences to help inform our understanding of the evolutionary relationships here, so, without the benefit of genetic study, we are left to rely on the nuances of color patterning to make our determinations. These differences in coloration are useful characters for study, given that sexual selection is clearly helping to drive speciation here, but a precise breakdown of the interrelationships still eludes us.
In examining the above cladogram, two major lineages can be seen. The cyanopleura clade houses one species with two phenotypes, namely Cirrhilabrus cyanopleura and (depending on your taxonomic stance) C. ryukyuensis. The solorensis clade houses all the other members, including: C. solorensis, C. aurantidorsalis, C. luteovittatus, C. randalli and two other scientifically undescribed phenotypes. Most of the group members occupy partially sympatric or parapatric ranges, with C. randalli being the only species attaining an allopatric distribution, and even that is not known for certain. A more in-depth look at their distributions will be covered later on.
Together, the cyanopleura group can be diagnosed easily based on a few key characteristics shared amongst all the members. It is important to note that the members of this group can be wildly variable, especially for those in the solorensis clade. As such, although diagnosing these species from other Cirrhilabrus groups may be easy, identifying them down to species level can be a process fraught with infuriating frustration. As an added level of complication, the group members are also able to hybridize, and in this article we again revisit this infrequently discussed topic.
All males in this group possess on their median fins, an intricate network of sinuous squiggles, usually in blue or yellow. This characteristic made a brief cameo in Cirrhilabrus scottorum and C. melanomarginatus of the scottorum group, and foreshadowed a cladistic relationship between the two. Like the scottorum group members, the cyanopleura group members are also fairly burley. Allen and Erdmann lists the maximum size for the group members at 10-11 cm, but aquarium housed specimens have the potential to get much larger, up to 15cm. Their caudal fins are rounded to weakly triangular in all but the largest and most terminal males, in which they become strongly rhomboidal. The first rays of the pelvic fins are moderately elongated (reaching to near the anal fin origin) and noticeably longer than those in the short-finned clade (e.g. lubbocki, lanceolatus, bathyphilus and lunatus).
The males are without any lateral or facial stripe, which are common characters seen in most other groups. Instead, they possess very strongly defined scale margins on the body, which overlaps to give a “chainmail” like appearance. This is a very unique characteristic restricted to members of this group, with the exception of the unrelated C. rubrisquamis. Some aquarists have used the superficial similarities of this species as justification for its inclusion alongside the cyanopleura group, but it is clear from the considerable differences in nuptial patterns and pelvic fin shape that this is not so.
An additional set of characteristics that is confined only to the solorensis clade in this group is the heavy shading of the operculum. The clade members generally possess either blue markings or dusting along the pre-operculum and operculum flap, and in some species, this can be so noticeable that is forms a distinct chevron on the gill plate. The males of the solorensis clade may possess contrastingly colored hoods on their face, but this only extends (dorsally) to the origin of the dorsal fin, versus the more posterior hood of cyanopleura.
The females of cyanopleura are rather drab and somber but possess a bi-colored “hood” on the anterior that demarcates from the rest of the body. The solorensis clade females are more uniformy colored, without a clear “hood” seen in C. cyanopleura, instead having a burgundy-red head. There are typically six poorly defined lines running along lengthwise along the body, which are composed of numerous minute, reflective-blue spots. This is a feature most closely shared with the scottorum group, which is the presumed closest relative of cyanopleura. Juveniles are mostly maroon to greenish with a single peduncular spot and a white tipped snout – an appearance shared by many other species in various groups and is therefore of limited use as a diagnostic feature.
Throughout this Cirrhilabrus series, we’ve only highlighted the physical characteristics that set the various groups apart. This is the first time we’re introducing a behavioral characteristic, and one example seen here is the unusual propensity for large male congregations. Unlike many Cirrhilabrus, where males are greatly outnumbered by females, males of the cyanopleura group are often seen in large flocks, sometimes outnumbering or equaling the number of available females.
It has been suggested that the cyanopleura group members are incapable of flashing iridescence during their courtship displays. Strangely enough, little, if any, photographic documentation exists showing the group members in nuptial form. It appears that color change during nuptial display is limited and reduced to only the lightening of the dorsal fin, with no change in overall body coloration, nor is there a presence of metallic iridescence or lightening of the body as seen in all other fairy wrasses.
In a study published by Gerlach et al, it was concluded that males of Cirrhilabrus solorensis emit red fluorescence at 650-700nm during displays of courtship and aggression. This is near the very edge of what is visible to the human eye and explains why these markings appear dark in color rather than red. The males not only produce this fluorescence, but they also are able to see and recognize it. This was concluded via a series of experiments using mirrors with and without filters to absorb red light. The males exhibited aggression towards their regular reflections, but exhibited no aggression when presented with a reflection that had the red light filtered out. A third mirror, where a filter was used to selectively absorb all but red light was used, and, unusually, no aggression was reported. It appears that red by itself, is not enough to elicit an aggressive response, and the males apparently need to have the full spectrum outline to determine whether or not the intruding fish is a rival or not.
Perhaps the interaction between males and females of the cyanopleura group are largely dependent on their ability to see such fluorescence, which would otherwise be non-apparent to the human eye without the use of a filter. If so, then the lack of chromatic brilliance during nuptial display is not so much an evolutionary disadvantage, but an advantage, seeing as most other Cirrhilabrus probably use physical color change as a behavioral cue. Also, keep in mind that red light becomes increasingly filtered out with increasing ocean depth, which, given the importance of this light for intraspecies communication, likely helps explain why the cyanopleura group is found in relatively shallow waters.
[Update] The macro photographs highlighting the dorsal and caudal fin characteristics were added post completion of this article.
The cyanopleura clade
The cyanopleura clade is home to two phenotypes and (depending on your taxonomic standpoint), consists of either one or two species. In 1904, Ishigawa noticed a difference in C. cyanopleura, in that certain populations of males develop a yellow flank just behind the pectoral fin. He proceeded to split the two, and the yellow flanked phenotype was elevated to species level – Cirrhilabrus ryukyuensis. Both forms are sympatric, but the latter is more evident in the northern territories, especially around Philippines and Japan. The sympatric overlap and weak evidence supporting speciation has generated mixed consensus on the validity of C. ryukyuensis as a legitimate species. In this article, we regard it as synonymous with C. cyanopleura due to their regular occurrence alongside one another in mixed groups.
Although the cyanopleura clade bears superficial resemblance to some of the solorensis clade members (such as C. luteovittatus and C. randalli), the lack of any shading on the operculum serves to distinguish them from the rest of the species. This may seem like a superficial distinction, but the presence, or lack thereof, of this trait will serve as a highly effective criterion in deciding the placement of the cyanopleura group members.
Cirrhilabrus cyanopleura
In this variably colored species, males are ochre to fir green on the head before transitioning into navy blue posteriorly. The blue hood gives this species its specific name “cyanopleura”, which translates to blue-side, although this in itself is rather misleading, as it is sometimes colored greenish or grey. The body is rather uniformly ochreous to fulvous orange or sometimes even salmon, and it is heavily obfuscated by the thickly edged scale margins, giving it a “chain-mailed” appearance. The scale margins are edged in dark green or violet, and are inconsistently distributed. More often than not, the scales immediately proximal to the navy hood are more heavily edged in violet compared to the other regions of the body. Constellations of metallic blue spots are sometimes present along its length. Ventrally, this species is unmarked and uniformly white (or sometimes a light yellow), with the lower head always being a pristine and blemish-free white.
The median fins are translucent blue to orange or yellow, and copiously adorned with yellow or cerulean sinuous squiggles throughout. The squiggling is very evident in matured males and can be so heavily present that the translucency of the fins becomes compromised, making it appear opaque instead.
The ventral fins are moderately trailing and long, much like those displayed in the scottorum group members. The caudal fin is roughly rhomboidal, becoming increasingly spade like as the males mature into their fully-grown terminal phase. Females are similar to the males, but show no distinction of a blue-sided hood; instead, the anterior region is pale greenish and poorly separated from the peach or orangey posterior half. Females often develop the sinuous fin markings and scale patterns at a larger size, while more juvenile specimens lack these traits.
As mentioned in the introduction, the cyanopleura group males have very limited abilities in their nuptial display. In courtship or aggressive display, the caudal, anal and ventral fins are clamped, while the dorsal fin is raised. The only noticeable color change during this event is the lightening of the posterior dorsal fin and the facial region. As with many Cirrhilabrus, males are able to puff up their gular region during display. Color change is very limited, and no observable iridescence is observed to develop specific to their nuptial form.
Cirrhilabrus cyanopleura is wide ranging, being found predominantly in the Western Pacific, where it occurs in the Ryukyu Islands (Japan), Taiwan, Thailand, Philippines, Papua New Guinea, Palau, Indonesia and south to the Great Barrier Reef. This species is weakly represented in the Indian Ocean, straying only to its easternmost periphery in the Similan Islands, Andaman Sea and Christmas Island.
This species occurs in large numbers above broken rubble reefs, and is often found mingling with other species of its genus, such as Cirrhilabrus lubbocki, Cirrhilabrus temminckii and Cirrhilabrus filamentosus. The population density in suitable areas may be so great that more than one male may be seen interacting together in a given space, an unusual occurrence for this genus.
Towards the Northern and Eastern portions of the Western Pacific, the evidence of a yellow-flanked phenotype takes precedence, although both are not mutually exclusive and are sympatric throughout much of their ranges. This form is treated by Ishigawa as a distinct species, known as Cirrhilabrus ryukyuensis.
This form is essentially identical in coloration to its parent species C. cyanopleura, but possesses on its flank an additional yellow blotch. This is where its relationship with C. luteovittatus and C. randalli becomes suspiciously evident, but the latter two species possess irrefutable characteristics linking them to the solorensis clade instead. The validity of this form as a species is subject of much debate amongst taxonomists and fish enthusiasts alike.
It can be argued that the ryukyuensis phenotype is a relatively young taxon still in the process of speciation. In this case where C. cyanopleura is sympatric, sexual selection is the only plausible pressure for divergence where females identify males based on this brightly colored yellow flank. The relative consistency in ryukyuensis’ appearance suggests that the two phenotypes do not regularly hybridize, and is further evident that this is a simple dominant/recessive allele turning the yellow on or off. However, whether or not the ryukyuensis form is indeed a diverging taxon capable of maintaining genetic distinction, or whether it will eventually hybridize back into a single homogenous taxon remains unknown for now.
Conversely, the yellow-flank can be seen as something that isn’t developed only in terminal males, but seen in young males and matured females as well. The occurrence of both forms cavorting throughout their range is evidence that this difference is perhaps nothing more than allelic variation. For the same reason that we don’t classify blonde Scandinavians as a separate species, there is perhaps little reason to recognize this regionally abundant “blonde cyanopleura” as its own taxon. The validity of its specific status is still subject to much debate, and, without further studies, nothing concrete can be said for now.
Like C. cyanopleura, the yellow-flanked form occurs in large aggregations above rubble patch reefs where they mingle with other species that occupy the same niche. The females are indistinguishable from C. cyanopleura, but are immediately identifiable as soon as they begin maturing, even before they turn “male”, as the yellow coloration forms relatively early in development.
The ryukyuensis phenotype is most apparent in the Ryukyu Islands (Japan), as well as the northern Philippines. It becomes progressively less common further south in Indonesia. Cirrhilabrus cyanopleura appears to be equally common throughout its range, whereas the “ryukyuensis” form is more restricted in its distribution.
As with Cirrhilabrus cyanopleura, the ryukyuensis phenotype exhibits weak changes in its nuptial display. Color change is restricted only to lightening of the dorsal fin and the nape immediately anterior to the dorsal fin. Like C. cyanopleura, displaying males tend to puff up their gular flap, which may be edged in blue during this event.
Both forms are exceedingly common in the aquarium trade and are of little value, being rather cheap and affordable. The species appeals greatly to the novice aquarist, ticking all the right boxes for affordability, hardiness and visual appeal. Both forms of this species are capable of forming hybrids with Cirrhilabrus solorensis, and possibly Cirrhilabrus luteovittatus, which will be discussed in detail later in this article.
The solorensis clade
The solorensis clade houses six phenotypes, four of which are described, while the other two await further studies. C. solorensis was the third Cirrhilabrus known and described by Bleeker in 1853, alongside C. temminckii and the reclassification of C. cyanopleura. The species descriptions were published in Bleeker’s Ichthyological Atlas To Indonesian Fish. The other five members include Cirrhilabrus aurantidorsalis, Cirrhilabrus luteovittatus, Cirrhilabrus randalli and two undescribed forms currently known as Cirrhilabrus cf. solorensis and Cirrhilabrus cf. aurantidorsalis.
With the exception of Cirrhilabrus luteovittatus and C. randalli, the solorensis group members are wholly confined to the Indonesian archipelago. A case of biogeographical uncertainty is displayed with Cirrhilabrus aurantidorsalis, C. solorensis and C. cf. aurantidorsalis, which will be elaborated upon in the individual species discussion. A diagnostic feature shared amongst members of this group is the possession of a marked operculum, which in C. solorensis is extremely ostentatious. The other members have it usually shaded in blue, especially on the pre-operculum cheek region.
Cirrhilabrus solorensis
C. solorensis was first known in 1853, when digital cameras, image scanners and other technological advancements were not available. Its description was based on a two page, barely informative paper published in Bleeker’s guidebook of Indonesian fishes. He later released a hand drawn illustration of the species in a separate publication, but the colors were not too accurately represented. The living coloration of C. solorensis was unknown to many then but eventually revealed itself through the passing of time.
This species bears one of the most unusual body colorations amongst the Cirrhilabrus. In this brilliantly colored wrasse, the ground color ranges from blue to teal to turquoise, depending on available lighting. The face is yolk yellow, darkening to cadmium orange at the nape. The operculum is heavily shaded in deep indigo, and extends quite far ventrally so as to form a collar connecting both sides at the gular region. The scales along the dorsum are thickly edged in the same indigo as the operculum, and these scales can be so copiously colored that they form a thick indigo band instead of the usual chainmail markings. The fins are translucent and decorated in the usual scrawling, and, in matured specimens, may be so dense as to completely compromise the translucency of the fins. Ventrally, the species is white and unmarked.
The ventral fins are moderately long and tapering, and the caudal fin is weakly rhomboidal, becoming increasingly spade-like in fully terminal males. Cirrhilabrus solorensis is not known to display any visible nuptial coloration, but, as mentioned in the group discussion previously, the males are able to emit red fluorescence in their excited state around the operculum and dorsum region. The females are peach to magenta to fulvous, with each scale margin along the body thickly edged in claret. The head is rosy with a variable dusky posterior, just at the start of the dorsal fin, and the ventral region is blue. The fins are hyaline and likewise riddled with the same sinuous markings as the males.
Females of C. solorensis are frightfully similar to the males of C. cf. solorensis from Bali, as well as the females of the other Indonesian clade members. This has led to many specimens being erroneously identified in the wild and in the trade; many of these identifications have been permanently etched in literature. The variability of the female form elsewhere in Cirrhilabrus is typically minimal, but Cirrhilabrus solorensis is a particularly mutable beast with few consistent characteristics. To further complicate things, the juveniles of C. solorensis are uniformly green, looking very dissimilar to the females. The females, being predominantly fulvous-rose colored, likewise look very dissimilar to the teal males. This means that a whole spectrum of transitioning colors can present themselves during the development of the species throughout its various life stages, further blurring the lines of identification.
Cirrhilabrus solorensis is confined to the Indonesian archipelago, where it ranges from the Flores and Banda Seas to Northeastern Sulawesi. Its westernmost limit in the Indonesian region lies in Bali, where it is rare. This species frequents shallow, disturbed reefs littered with dead Acropora rubble, often in close proximity to cyanide and dynamite exploited zones. Like the other cyanopleura group members, males are often seen flocking in large aggregations.
This species suffers the unfortunate fate of having its name erroneously translated. The epithet “solorensis” is derived from its type locality of the Solor Islands in Indonesia. Colloquially, this species is known in the trade and various literatures as the “Solar Wrasse”, whose name implies an etymological relationship with the sun. The difference between “Solor” and “Solar” may be only a single letter, but the implications it bears dramatically changes the etymology behind the species. Cirrhilabrus solorensis is extremely ubiquitous in the aquarium trade and is of little monetary value. Like Cirrhilabrus cyanopleura, its gaudy, almost fake and plastic-like coloration makes it a very popular choice for novice aquarists. This species is capable of forming hybrids with Cirrhilabrus cyanopleura and possibly with Cirrhilabrus aurantidorsalis.
Cirrhilabrus cf. solorensis
This is the first of two undescribed species in the solorensis clade, and prior to this, the fish has been known as Cirrhilabrus cf. cyanopleura in various literature. We feel that Cirrhilabrus cf. solorensis is more fitting for this phenotype considering its placement in this clade. The male of C. cf. solorensis is ferruginous-ochre along its body, with darker edged scales and a maraschino cherry head that extends posteriorly into a hood. This ochre body coloration sometimes extends, in matured males, to the dorsal fin origin, which is never seen in C. cyanopleura (whose hood is always distinctively demarcated from the rest of its body). The area behind the pectoral fin is sometimes, but not always, slightly tinted in violet, and the scaling just adjacent to this is always thickly edged in claret. The operculum is dusted in blue, and the entire ventral portion is white to sky blue and completely unmarked.
The fins are hyaline, but marked in the usual sinuous squiggles. The ventral fins are moderately long, and the caudal fin is rhomboidal only in terminal males. The males of this phenotype resemble the females of Cirrhilabrus solorensis very closely, and may cause initial confusion. However, with close scrutiny, the two can be rather confidently separated based on a few key characteristics. In C. cf. solorensis, the red hood always extends past the pectoral fin to cover roughly a third of the body. Females of C. solorensis, despite also having a red head, never have it extending past the pectoral fin base. Additionally, C. cf. solorensis is more coffee in its coloration, as compared to the females of C. solorensis, which tend to be more magenta shot.
The nuptial pattern for this phenotype is unknown, but it’s unlikely that they possess any significant change of coloration during display. Some lightening of the dorsal fin may be expected. Juveniles are a dirty olive green, which quickly mellow into a somber orange-brown as they mature into females. The females are, in the typical fashion of this group, drab and adorned with a series of lineated spotting near the dorsum. As they transition into the male form, the head intensifies into the classic maraschino cherry red, and the scales along the flank develop the thick claret margins.
For as long as the two species have been made available to the hobby, both physical and digital literature have been plagued with widespread confusion and misidentification. Because the males of this species are so similar to the females of the former, aquarists have tried, in much futility, to place the two together in hopes of creating a sexually functional pair or a harem. Males of C. solorensis and C. cf. solorensis are generally quite belligerent and will not likely tolerate each other in the confines of a small tank.
Cirrhilabrus cf. solorensis has by far, the smallest range in this group. It is currently only known from Bali, where it breaches the periphery of the Indian Ocean. It is, in all likelihood, probably found elsewhere surrounding its current locality, but its geographical distribution is probably less extensive than the other clade members. The possible extension of this species into the Komodo region is discussed at the end of this article. Likewise, so is its possible terminal male coloration, which seems to be rather elusive for this phenotype. Like Cirrhilabrus solorensis, this species is fond of coastal silty bays and offshore reefs replete with broken rubble. The flat, monotonous and open habitat is often colonized by low-lying soft coral such as Xenia and Sinularia, in which the females and males frequently cavort around.
Not surprisingly, the males and females are often seen swimming in large flocks, with an unusually skewed sex ratio very unlike other species in the genus. This form is sympatric with many species in its habitat, and is found in the company of C. lubbocki, C. solorensis, C. cyanopleura and C. exquisitus. The hooded appearance is very distinctive for this form, but seeing as the name “Hooded Fairy Wrasse” has already been claimed by Cirrhilabrus bathyphilus, we’re proposing the colloquial name of “Red-head Fairy Wrasse” to differentiate this species from C. solorensis.
This phenotype has most often been confused with Cirrhilabrus cyanopleura, in part because they occur together in Bali, and also because the males of C. cf. solorensis are very similar to various females of other closely related species. For instance, Gerry Allen regards these to be a local male variant of Cirrhilabrus cyanopleura, while Rudie Kuiter regards these as female.
This “species” is fairly common in the trade, and is frequently seen in imports originating from Bali, or having livestock that pass through facilities carrying Balinese fish. It is very inexpensive, and as previously mentioned, is often sold erroneously as C. solorensis or even C. cyanopleura.
[Update] The above two images were sent to us by Dr. Trond Erik Vee Aune from Norway post completion of the article. This appears to be the terminal male form of this “species”. At 16 cm, it is also far larger than its recorded maximum length in the wild, suggesting that members of this group do attain sizes comparable to those of the scottorum group. The development of the purple area proximal to the red head and intensification of the ocherous back suggests that this “species” is perhaps more likely to be related with Cirrhilabrus aurantidorsalis and Cirrhilabrus cf. aurantidorsalis instead.
Cirrhilabrus aurantidorsalis
This is a beautiful species with a very fitting and descriptive name. Cirrhilabrus aurantidorsalis is, as its name suggests, decorated with a thick, copious amount of orange on its dorsum. This can range from bright golden-yellow to mustard to rich cadmium orange, although the latter is most common. The head is fuchsia to magenta, and the body is blue to purple. The typical chainmail pattern is seen along its entire length, but only in places where the golden-orange back does not occupy. The operculum is shaded in blue, and the fins are translucent, superimposed with the usual scrawling. The caudal fin is strongly rhomboidal in terminal males.
No nuptial colors have been documented in this species so far, and as with the others, it most probably has very limited abilities in chromatic display. This species is the least sexually dichromatic of the group, and perhaps even the genus. The females of Cirrhilabrus aurantidorsalis are similar to the males, and have orange backs in all stages with the exception of very small juveniles, which are dusky brown and unmarked. The intensity and extensiveness of the orange backs, of course, are more pronounced in matured and terminal males.
Cirrhilabrus aurantidorsalis has a very restricted range, being found predominantly within the confines of Sulawesi, specifically within the Gulf of Tomini. It is most often seen in the Togean Islands, and it strays to the northeastern tip of Sulawesi in the straits of Lembeh. South of this range, it is replaced by a very similar species, Cirrhilabrus cf. aurantidorsalis. The emergence of C. aurantidorsalis as a species is probably relatively recent, and to understand this, a look into the biogeographical history of its range is necessary.
The Gulf of Tomini was formed during the late Neogene collision between the East Sulawesi Ophiolite Belt and the micro continent Banggai-Sula platform. About 2.8-5.3 million years ago since the Pliocene, submarine sediment gravity flow was the major mechanism of sediment transportation from the slope to deep-sea environments in the Tomoni and Gorontalo Basins (Kusnida and Subarshyah, 2008). The resultant formation of the bay served as an isolation barrier, locking in its species and setting the platform for evolution. Cirrhilabrus aurantidorsalis is one of a handful of species endemic to the region, and shares its habitat with the evolutionarily unique Paracheilinus togeanensis. The video below shows the formation of the Banda Arc, and during the process, the inevitable formation of the Gulf of Tomini (in lime green) can be followed.
Cirrhilabrus aurantidorsalis is closely allied and sister to Cirrhilabrus cf. aurantidorsalis of the Banda island arc, and together, the two seem to form a cladistic pair. Biogeographically, the two phenotypes are sympatric only in the straits of Lembeh, where they narrowly mix. Further within the Gulf of Tomini, the turbulent waters of the Molucca Seas probably creates a barrier, isolating the two. Whether or not the two species once swam together prior to their current “disjunct” ranges, or whether or not they evolved convergently is left to be unanswered. Cirrhilabrus aurantidorsalis could be speciating right now due to its geographical isolation, or the two population might have already been speciated, but recently reconnected in their ranges. Not enough is known. Cirrhilabrus aurantidorsalis possibly hybridizes with C. cf. aurantidorsalis and C. solorensis in Lembeh and Sulawesi.
This species is fairly uncommon, but is never expensive.
Cirrhilabrus cf. aurantidorsalis
Cirrhilabrus cf. aurantidorsalis is very similar to its preceding sister, and is colored nearly exactly the same except for major differences in the head and ventral regions. In this phenotype, the head is a dusky blue-grey and the operculum is heavily dusted in blue. The pre-operculum and operculum shading is strongest in this species, and can be so prominent that a chevron marking tracing the indentation of the gill plate can be seen. The ventral region just beneath the orange back is less purple than the former, and is light blue. The dorsum is less cloyingly orange than C. aurantidorsalis, and tends to be more suffused. The median fins are of the usual translucent nature, decorated with yellow and blue sinuous scrawling. The tails are rhomboidal in large terminal phased males.
The males are not documented to display any nuptial coloration. Unlike Cirrhilabrus aurantidorsalis, this form is very sexually dichromatic, and only the males develop the orange back. The females are a dusky greenish-grey and adorned all over with the chainmail like markings of this group. During transition into the male form, the dorsum lightens and takes on the characteristic orangey-back.
Cirrhilabrus cf. aurantidorsalis is found throughout the Banda Archipelago, being found commonly in Komodo, Flores, Timor, and following the Banda Arc eastwards to the Kai Islands and Ambon. It reaches its western limit in Bali, and its northern limit in the straits of Lembeh, where it mixes in a narrow contact zone with its sister, C. aurantidorsalis. Kuiter suggests the name “Dull-head Fairy Wrasse”, after its blue-grey head. We’re proposing in this article the usage of “Banda Fairy Wrasse” as the colloquial name, as it reflects this variant’s distribution with respect to the other clade members.
As explained in C. aurantidorsalis, the relationship between these two forms are unclear. The Molucca Seas probably limit the invasion of C. cf. aurantidorsalis further into Sulawesi, allowing C. aurantidorsalis to diverge genetically. However, whether or not C. aurantidorsalis is currently undergoing speciation at the edge of this geographical range is unclear, and likewise whether or not this geographic connection is a recent bridge from a previously disjunct range is also unclear. At the northern limit in Lembeh, C. cf. aurantidorsalis should be expected to hybridize with C. aurantidorsalis. A possible hybrid is discussed in the hybrid section at the end of this article.
Surprisingly, this species is very rarely seen in the trade. It has undoubtedly penetrated the aquarium market already, unbeknownst to aquarists, as seen in Dr. Hiroyuki Tanaka’s captive specimen above. The existence of this species in the trade is probably incognito, seeing as many members in this clade are easily confused with each other.
[Update] The above photo of Cirrhilabrus cf. aurantidorsalis was added post completion of this article. The specimens were collected from Darwin in the northern territory of Australia. This presents a previously undocumented range extension of the species from the Indonesian Archipelago. It has been speculated that certain reef fishes are able to cross the Indonesian-Australian divide, which are proximal, but separated by the Banda and Timor Seas. The collection of this fish in Darwin is possibly the first record of the genus crossing this divide into Australia’s northernmost territory. Another Cirrhilabrus was collected along with this, and that will be described in a separate article.
Cirrhilabrus luteovittatus
In Cirrhilabrus luteovittatus, males range from a rich burgundy to bordeaux and lack any distinct posterior hood. A very faint and thin yellow-orange stripe presents itself just beneath the dorsal fin. As with the other group members, the scales are edged thickly in dark violet, but this characteristic, along with its operculum markings, are less obtrusive in this species due to its dark ground coloration. The specific epithet luteovittatus translates to “yellow-stripe”, and this is very clearly displayed in the males. An equatorial belt of saffron yellow runs horizontally along its length, starting just behind the pectoral fin and tapering off at the caudal peduncle. The ventral portion is a lighter, mangosteen purple to white.
The fins are translucent yellow and are copiously riddled with the sinuous squiggling characteristic of this species group. The caudal fin is a rough rhombus, becoming increasingly spade like in terminal males. The ventral fins are in the usual form for this group and are of moderate length. Females of C. luteovittatus are of the usual form, being relatively drab and unmarked with a series of fine spotting along the dorsum. They range from pale greenish-brown to light purple depending on their relative maturity.
Oddly enough, Cirrhilabrus luteovittatus is quite susceptible to aberrations, with numerous photographic evidence of this species being subjected to high levels of xanthism. Aberrations are common in certain genera of fish, but Cirrhilabrus seems to usually be immune.
A fairly common aberration involves C. luteovittatus developing a highly xanthic dorsum, which in extreme cases can totally obliterate the underlying burgundy ground color and merge with the existing yellow stripe. It is not known if this coloration can be successfully maintained in captivity, or whether or not it is simply transient. This xanthic aberration has been photographed in the wild as well, and it appears to only affect males. A plausible cause for this could be attributed to the yellow-orange dorsal mark being greatly exaggerated downwards.
The nuptial coloration of C. luteovittatus is poorly documented, but like other members in the group, they appear to lack any definitive nuptial pattern. From the very few photos of this species in situ, it appears that the body stripe lightens to a pale chalk, while the rest of the body remains unchanged.
Although it would seem logical to classify C. luteovittatus and C. randalli as sisters in the phylogenetic tree, the biogeography between the two species does not fully support that conjecture. The yellow equatorial streak in both species could be regarded as a shared trait, once widespread across the Pacific but subsequently lost in the evolution of the other group members.
C. luteovittatus is distributed primarily within the Federated States of Micronesia and the Marshall Islands. It has also been recorded in Johnston Atoll. Like all other Cirrhilabrus, they generally inhabit steep rocky rubble slopes at depths up to 30m (100ft). This is the deepest occurring member of the cyanopleura group, and the very prominent yellow band probably aids in communication down in these depths the same way red does in shallower waters. The species can be found in low-lying reefs dominated by Halimeda and Porites, in which the females hover in close association. This habitat’s flora and fauna is quite niche and specific to the Micronesian and Marshall Island chains, and is shared with a few other sympatric species such as Cirrhilabrus johnsoni and C. rhomboidalis.
Cirrhilabrus luteovittatus is relatively uncommon in the trade, but it is affordable and only moderately expensive. This species possibly strays into Raja Ampat, where it may hybridize with C. cyanopleura.
Cirrhilabrus randalli
Cirrhilabrus randalli is one of the least known of the genus, and in this enigmatic species, the males bear the greatest resemblance to Cirrhilabrus luteovittatus. C. randalli is ferruginous-brown or rust-colored basally. The head is cloaked in an inky blue-green hood that spreads to the posterior portion of the body, in much the same fashion that is seen in C. cyanopleura. A bright yellow equatorial belt runs horizontally along its length in the same way it does for C. luteovittatus and tapers toward the caudal peduncle. The body scales, as usual, are edged thickly in claret, giving the species the characteristic “chain-mailed” appearance. Ventrally, this species is unmarked and is white.
The median fins are translucent blue and overlaid in the same sinuous scrawling. The pelvic fins are moderately long and tapering, and the caudal fins are rhomboidal. Females resemble those of the cyanopleura group, and are uniform greenish-brown with the usual spotting along the dorsum.
C. randalli is an exceedingly poorly documented species, with very little known to its name. It doesn’t appear to have any significant nuptial pattern, and displays in the same way C. cyanopleura does. The ventral, anal and caudal fins clamp up while the dorsal is raised. The posterior portion appears to lighten significantly, and so does the nape.
It is chiefly restricted to Western Australia, in the rubble pans of Hibernia Reef and Rowley Shoals in the Eastern Indian Ocean. It shares this endemic range with Cirrhilabrus morrisoni, and the highly atypical Conniella apterygia. In the lanceolatus group article, we attributed the lack of ventral fins in Conniella to a genetic bottleneck event. What’s unusual is that although sympatric and exposed to the exact same conditions, C. randalli appears to have retained all normalcy in its morphological form. The same can be said for the third endemic wrasse in Northwestern Australia, C. morrisoni, but that is a subject for a future article in this series.
As previously mentioned in C. luteovittatus, C. randalli and the former may appear to be sisters, but their geographical range does not fully support this hypothesis. In all likelihood, this characteristic was either independently evolved in both taxa or present in their shared common ancestor. The similarities to cyanopleura (specifically the ryukyuensis form) further suggest that the hooded pattern and yellow lateral patterning are a basal trait in the cyanopleura group. One important characteristic that identifies randalli as more closely related to solorensis than cyanopleura is the extent of the hood in mature males. While the hood of cyanopleura extends past the origin of the dorsal fin, that in randalli begins closer to this origin, giving the hood an irregular outline posteriorly.
Cirrhilabrus randalli is essentially a book fish, and the species has never been (and probably will never be) collected for the aquarium trade due to its isolated and far-flung range. Although this species has not been documented outside of its range, a few curious specimens that appear to be hybrids with traits of C. randalli have been documented in the Indonesian archipelago. Northwestern Australia is not too far off, and it is possible that this species waifs to Indonesia in exceedingly rare occurrences. More on this will be discussed in the hybrid section below.
Hybrids
While hybridization events are rarely documented in Cirrhilabrus, we’ve seen some examples from the lunatus and scottorum groups, with the latter engaging in intra-group hybridization with Cirrhilabrus exquisitus. The major bulk of hybrids occur in the cyanopleura group, which is unsurprising seeing as there are so many highly similar and closely related taxa here. While some of the hybrids are easily diagnosed, a few are iffy and highly subjective.
Cirrhilabrus solorensis hybridizes with C. cyanopleura in areas where the two are sympatric. Despite their presumably distant evolutionary separation from one another, C. cyanopleura and its yellow-flanked “ryukyuensis” form are both capable of hybridizing with C. solorensis. The image above shows a male C. solorensis x C. cyanopleura. While the expression of solorensis traits are not extremely apparent, it does manifest itself nicely in the heavily shaded operculum. The scaling along the anterior dorsum is also noticeably darker, a trait that is very evident in males of C. solorensis. Compare the hybrid with the pedigree C. cyanopleura in the background, and these traits become immediately apparent.
Here we see the ryukyuensis form of cyanopleura hybridizing with C. solorensis. This hybrid individual appears to still be in the female stage, or at least transitioning into the male form. The reddish head and operculum markings are consistent with those of C. solorensis in the female form, and the light yellow flank corresponds to a development of the trademark ryukyuensis phenotype.
It is possible that Cirrhilabrus solorensis is able to form hybrids with Cirrhilabrus aurantidorsalis in Sulawesi, and in at least one photographic documentation, this seems to be highly plausible. The lightening of the indigo scales and the faint emergence of an underlying orange along the dorsum in the specimen of C. solorensis above seems to suggest some genetic input from C. aurantidorsalis. The muddying of the facial region might also correlate to the largely dark purple-magenta face of C. aurantidorsalis. Unlike the previous two cases above, however, this seems to be more contentious and subject to educated guessing.
Cirrhilabrus cf. solorensis, in its confined geographical range of Bali, is also capable of hybridizing. Its selection of mates here however is restricted only to Cirrhilabrus cyanopleura and C. solorensis (the latter being very rare in Bali). Hybrids with the former are not uncommon, and are very variable in their form. The amount of phenotypic expression from each parent ranges between specimens, and in the three individuals above, the amount of green displayed from the genetic input of C. cyanopleura varies in its intensity, clarity and position.
These hybrids often appear very similar to their pedigree parents, especially in specimens that lean more toward one parental phenotype. Not only does this make identifying them very difficult, it also fuels the already numerous misidentification in the aquarium trade.
[Update] The above three photos of Cirrhilabrus cf. solorensis x C. cyanopleura were added post completion of this article. These were photographed in situ at Bali, where Cirrhilabrus cf. solorensis occurs in exceedingly large numbers at the various local wholesalers. We managed to chance upon some of these hybrids cavorting with various other species.
The specimen above is an unusual individual that sports the characteristic pre-operculum chevroned-shading associated with Cirrhilabrus cf. aurantidorsalis. The blunt, truncated head shape also points in the direction of that “species”. This fish was photographed in Lembeh in Northeast Sulawesi, putting it in contact with its sister C. aurantidorsalis. It is highly possible that we’re looking at a hybrid between the two sisters, or not. Without genetic material to sequence, no conclusion can be made. The female forms and the individual parents are far too variable to produce any consistent looking hybrids. Cirrhilabrus solorensis may even be in the mix, seeing as the species is found here as well, and the females in possession of a red head.
Are we looking at a female C. cf. aurantidorsalis in transition, or are we looking at a hybrid between the two sisters? The heavily magenta shot face and ventral region seems to correlate nicely with that of C. aurantidorsalis, and the idea that this may be a hybrid does not seem all that unlikely. Still, this is another example where lines are blurred, and only educated guesses can be put forth.
Yet another possible hybrid involving Cirrhilabrus cf. aurantidorsalis occurs in the Banda Archipelago of Indonesia. The dusky head and pre-operculum markings strongly suggest genetic input from this “species”, but what about that vestigial yellow streak? The ryukyuensis form of C. cyanopleura never develops such extensive elongation of its yellow flank, and this could possibly point to the occurrence of C. randalli in Indonesia.
As previously mentioned in C. randalli, the northwestern region of Australia isn’t that far off from the Indonesian island chains, specifically the Banda Arc. Should the very unlikely, but not impossible, chance that C. randalli waifs to Indonesia, would it be able to hybridize with its other clade members out of desperation to find a mate? Could we be looking at a hybrid between C. randalli and C. cf. aurantidorsalis? The extensive hooded marking on the posterior dorsum seems to suggest this. Again, as contentious as this may sound, the likelihood of this occurring is probably less ridiculous than initially anticipated. However with very little to go on, this is just perhaps, another educated guess. C. cyanopleura may also be another candidate for hybridization, as seen in the photo above.
The exact same scenario can be said with Cirrhilabrus luteovittatus from the Micronesian island chains. The specimen above, photographed in Raja Ampat, shows the ryukyuensis form of C. cyanopleura with an exaggerated elongation of the yellow flank, as well as obvious shading on the pre-operculum and operculum regions. The snout is also significantly reddened, and the yellow dorsal stripe from C. luteovittatus is strongly evident. This would suggest genetic involvement with one of the striped species of the solorensis clade, and with C. randalli confined to the far-flung region of Northwestern Australia, Cirrhilabrus luteovittatus from Micronesia seems more likely.
C. luteovittatus is allopatric in distribution with regards to its group members, but should it waif to nearby Raja Ampat in the Papuan region, there is, in all likelihood, a chance for a hybridization event to occur.
Unknowns
Despite our best efforts in trying to resolve this group, there are inevitably some open-ended mysteries limited by our capabilities. Not only are we unable to resolve the phylogeny and cladistic relationships, we are also unable to fully understand and rationalize the various hybrid combinations occurring throughout Indonesia. To make things even more trying, there is one final cyanopleura group phenotype that we cannot explain.
This appears to be highly similar to the Balinese red headed Cirrhilabrus cf. solorensis, but the maraschino cherry hood in this form never extends pass the pectoral fin base. Additionally, a green wedge is always present just behind of the hood, at the base of the dorsal fin.
All of these specimens apparently occur only in Komodo. Could this be a regional form of Cirrhilabrus cf. solorensis? Is the development of the green wedge a terminal male characteristic? Komodo exists east of Bali, past a major environmental barrier in the form of the turbulent waters of the Lombok Strait. Red-headed wrasses have yet to be documented between these regions, though it’s not implausible that they occur east of Bali. Perhaps what we are seeing here is a mix of Red-head and Banda wrasse DNA, or perhaps we still know too little about the variability present in these taxa to draw firm conclusions.
This male with the same green patch above was photographed in Bali, alongside the typical redhead phenotype. The specimen above is 10cm in length, far larger than the usual size at which this phenotype is often photographed. Perhaps this “species” is indeed synonymous with the Komodo population. So does Cirrhilabrus cf. solorensis range outside of Bali, east to Komodo? Again, too many questions, and very little answers. This teal coloration here might even be indicative of a sister relationship with Cirrhilabrus solorensis, which is rare in Bali, making hybridization all the more likely.
The cyanopleura group is by far the most challenging, taxing and mind-numbing of the Cirrhilabrus groups so far, and this is only the beginning. It is essentially a phylogenetic cipher, displaying evolutionary biology in its purest, most complex and intimate of forms. Future installations will feature the exquisitus complex and the temminckii group from the genus’ third clade, both of which are also ostentatiously complex and difficult.
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