Cirrhilabrus johnsoni was first described in 1988 based on specimens collected in the Marshall and Caroline islands. This small species served as the twentieth member of a rapidly expanding genus, and was decidedly different with a crescent shaped caudal fin adorned with long filamentous extensions. It was only three years later that another species of similar stature was discovered in Japan, and Cirrhilabrus lunatus officially joined the genus as the twenty-fifth member in 1991.
The lunatus group features small to medium sized members confined within the Pacific Ocean. This group is highly unusual in that four out of the six phenotypes share a sympatric distribution in the northern tip of the Philippines. The only completely allopatric members are C. squirei and C. johnsoni.
The crescent tail is highly diagnostic of this group and the males of all members (with the exception of the “pintail” fairy wrasse) are readily identified based on this trait. Another trait that most males in this group share is the presence of two strongly marked stripes, which correspond to the separate sections of the lateral line: one dorsally and one medially. The medial stripe extends forward to the pectoral fin, where it then turns upwards along the fin’s base.
The presence of these stripes draw similarities with two other species, and they are Cirrhilabrus laboutei and Cirrhilabrus exquisitus. Whether these lateral line stripes are viewed as a derived character for these three groups or, instead, as a trait common to the entire genus has major implications for deciphering the genus’ evolutionary history. There are differences (to be discussed in future articles), which suggests that the lunatus group is not particularly closely related to either C. laboutei or C. exquisitus, despite their similar color patterns.
The caudal fins in the crescent tailed members are submarginally colored in cobalt with a hyaline posterior border. This caudal fin pattern can be regarded as an apomorphic trait unique to this group, and is seen in all members except the “pintail” wrasse.
The juvenile forms of this group are relatively consistent, with a ground color of orange to red. They have three prominent white stripes, with thinner stripes present variably between them. Along the main stripes are a series of white spots, which are often retained into adulthood where they become visible during displays of stress coloration.
In the previously hypothesized phylogenetic tree, the lunatus group is placed alongside the lanceolatus group, with the bathyphilus group being basal to both. These three groups form a fairly straightforward clade based on the shared similarities of the short pelvic fins and similar juvenile coloration. The juvenile/immature female of Cirrhilabrus lunatus above is characteristic for all its group members, and is very similar to that of C. lanceolatus. The fact that both groups share similar juvenile phenotypic traits as well as at least one member of each group possessing a lancet shaped caudal fin suggests quite strongly the closeness of their relationship.
Specifically, the “pintail” fairy wrasse from the lunatus group has an almost identical caudal fin shape and coloration (paired diagonal blue lines) to that of the lanceolatus group forming a link between the two.
Cirrhilabrus lunatus
A charming species bearing the “crescent tailed” moniker, C. lunatus cannot be confused with any other Cirrhilabrus in its range. In this elegant species, the males are very variable in coloration but are usually a rich tangerine. Shades of green or purple are not uncommonly seen slated over the ground coloration, and in some specimens this can be strong enough to mask the underlying orange.
As with many of the group members, the diagnostic stripe markings are present in this species as well, although not as clearly defined or exaggerated. A broad yellow stripe of substantial thickness begins at the pectoral fin base and extends posteriorly to near the start of the medial portion of the lateral line; but this never reaches the caudal peduncle. The dorsal stripe is reduced to a yellow suffusion, and although noticeable enough as a feature, is not bordered by margins or lines.
The median fins are sooty grey to black and bordered by metallic cobalt. Rather interestingly, the males have an ability to superimpose their entire ventral half in a matte grey shade, giving them a distinctive bi-colored pattern. It’s unknown whether this coloration is directly correlated to behavior or mood, as it can be seen in both (although not exclusively) resting and nuptial individuals.
The nuptial pattern for C. lunatus is similar to its resting form, except for an increase in color brilliance. The yellow stripe becomes more intense, and the median fins take on a lustrous sheen of scintillating cobalt. The black shading is variable and may or may not be displayed during nuptial flashing. Some individuals “turn off” this black shading completely during display, and its purpose or trigger is not clearly known.
C. lunatus is almost strictly Japanese in its distribution, being found predominantly in Okinawa, Ogasawara, Izu, Bonin and the Kochi prefecture. Here it is sympatric with a host of other Cirrhilabrus, but is most often seen together with the “pintail” fairy wrasse, Cirrhilabrus katoi and C. lanceolatus. It hybridizes with the “pintail” fairy wrasse to form a rather rare hybrid, which will be touched upon at the end of this article.
Taiwan appears to be within its documented range as well, but specimens are rare here and are likely strays from Japan. Whether or not this species extends further south into the Philippines is questionable, but like the “pintail” wrasse, it might not be entirely implausible. In Indonesia and the Philippines, it is replaced by a rather confusing and highly similar “species” that warrants further investigation.
Cirrhilabrus lunatus is infrequently collected for the aquarium trade, but does make sporadic appearances now and then. It commands a high price whenever it shows up, but is never in any abundance.
[Update] In July of 2015, post completion of this article, Cirrhilabrus lunatus was reported and captured for the first time in Aparri, Cagayan, in the northern most tip of the Philippines. This serves as a previously undocumented range extension, and puts this species in close sympatry with C. cf. lunatus, C. brunneus and the “pintail” fairy wrasse.
Cirrhilabrus johnsoni
Cirrhilabrus johnsoni is a beautiful species with a fulvous orange body coloration and carmine fins. The males are very consistent in their appearance in are not nearly as variable as Cirrhilabrus lunatus. The typical dorsal and medial stripes are both present in this species; however, in the latter, it is always broken midway near the anal region and is never complete.
This species is unique for possessing an epaulette above its pectoral fin. After curving dorsally over the pectoral fin base, the ventral stripe expands into the irregularly shaped epaulette patch, where the dorsal stripe is also connected to. The caudal fin is emarginated, with cobalt submarginally and a hyaline posterior border. Cirrhilabrus johnsoni is inconspicuous in the field, and appears grey underwater. Coupled with its small size, this species is easily overlooked by divers.
The nuptial coloration of C. Johnsoni, however, is remarkably stunning and quite unlike its innocuous resting form. The body coloration intensifies from fulvous to cadmium orange, and the fins turn opaque carmine. The stripes and pectoral epaulette glitter in an electrifying teal, while the caudal fin margin scintillates cobalt.
Cirrhilabrus johnsoni was thought to be endemic to the Marshall Islands, but has since been discovered outside of this range to include other oceanic chains of Micronesia, such as Yap in the Caroline Islands. The sympatric Cirrhilabrus rhomboidalis and Paracheilinus bellae have also enjoyed this range extension, and the species is undoubtedly present in other unexplored regions within the Federated States of Micronesia.
The habitat of C. johnsoni is typical of most Cirrhilabrus, with sparse rubble patches being a preferred choice. In Kwajalein atoll, it is commonly seen in large barren clearings where cyanobacteria and the calcareous Halimeda reign dominance. Cirrhilabrus balteatus is often seen mingling in close sympatry with C. johnsoni. Because of its isolated allopatry from the rest of the lunatus group members, C. johnsoni is unlikely to form any naturally occurring hybrids.
The extent of this species’ range is undetermined, and it is plausible that it might be found at depth in the Mariana Islands and Palau, in which case it would overlap with C. lunatus or C. brunneus respectively.
As expected, the females adopt the lunatus group template with orangey-red ground coloration, complete with the characteristic white striae and interconnecting spots. The anterior is notably yellow in C. johnsoni females, but, in other respects, it is identical to others in the lunatus group. The species is rare in the trade and very expensive.
[Update] The photo above featuring a harem of Cirrhilabrus johnsoni in a Halimeda patch in Kwajalein Atoll, Marshall Islands, was added post completion of this article.
Cirrhilabrus brunneus
As with the lubbocki group, a similar case of identical sympatric overlap occurs with two of the lunatus group members – Cirrhilabrus brunneus and Cirrhilabrus cf. lunatus. This raises some important questions on their validity as distinct species, as well as the relationship between the two. Cirrhilabrus brunneus is currently treated as a recognized taxon based on differences in coloration to Cirrhilabrus lunatus. It is the only member in this group that does not have a ground coloration of orange.
This species is characterized by its dusky brown coloration dorsally, the intensity of which can vary to an almost jet black. This gives rise to its scientific name “brunneus”, meaning brown in latin.
The standard dorsal and medial stripes are mostly obscured in this species, but are still present, albeit with a few modifications. Cirrhilabrus brunneus has an extensive yellow venter, which is unique to this species in the lunatus group. The yellow ventral portion essentially serves as a modified stripe that is characteristic of the lunatus group. The dorsal stripe, however, is absent in this species. The median fins are black with a greenish tinge near the base, and, in the standard lunatus group fashion, the caudal fin is submarginally cobalt.
The nuptial pattern of Cirrhilabrus brunneus is similar to its resting form, but with a few alterations. In full display, the body darkens to a deep charcoal black, with intensification of the yellow venter. A coppery band develops above the pectoral fin dorsally, and the ventral, dorsal, anal and caudal fins turn opaque jet black. An interrupted stripe, like teeth on a zipper, appears in metallic cobalt at the base of the dorsal and anal fins.
As with other members of the lunatus group, the tail is highlighted submarginally with cobalt blue. The coppery band is unique to this species, and lingers on even after nuptial flashing. It appears whenever the fish is excited or aggravated, and is analogous to the irregularly shaped epaulette in C. johnsoni.
Cirrhilabrus brunneus is found in deep waters, generally below 130ft. There is reason to believe that this species occurs deeper as well. The type locality for the species is Northeastern Kalimantan, Indonesia, but it has since been discovered further north to the Philippines. In both locations it overlaps perfectly with Cirrhilabrus cf. lunatus, and the two not only occur in the same range, but also mingle in the same habitat.
Cirrhilabrus brunneus, despite being found in Indonesia and the Philippines, is known from surprisingly few specimens. It is exceedingly rare in the trade with only a handful of appearances. The juvenile and female forms are poorly known, but are believed to follow the standard lunatus group appearance. A few specimens with entirely dark mahogany “brunneus-like” characteristics have surfaced, which may indicate a mature female or transitioning form of the species.
Little photographic documentation of this species exists in the wild, and it’s probably attributed to its deepwater nature. As with most Cirrhilabrus, typical rubble patches along steep slopes are favored habitats. C. brunneus is strongly involved in the description of the next lunatus group member, Cirrhilabrus cf. lunatus.
Cirrhilabrus cf. lunatus
Cirrhilabrus cf. lunatus has a ground coloration of orange with an intricate web of yellow spots and lines on its face and venter. The classic double stripes running along the lateral line are seen very clearly here, manifesting themselves in a beautiful lilac color. The median fins are black, and in the usual fashion, are tinged in cobalt. This is especially so for the caudal fin. This species lacks any visible epaulette or “patches”, as seen in C. brunneus and C. johnsoni. The caudal peduncle develops a dark sleeve in large males.
You may have noticed the absence of Cirrhilabrus cf. lunatus on the phylogenetic tree in the introduction, despite its sympatric overlay with C. brunneus on the biogeographical map. It’s status as a valid species is precarious at best, and for that reason it was left out of the tree.
This is also the first time we’re introducing the term “cf”, and it is used when a taxonomically undetermined species is compared against a known one of similar appearance. It means, “to confer”, and in this case, Cirrhilabrus lunatus is the model for comparison. In that regard, however, Cirrhilabrus cf. lunatus differs by possessing the strong yellow spots and reticulations that C. lunatus lacks. The distinct paired lilac stripes are also absent in C. lunatus, although the broad yellow band present on the former is seen as a weak inkling on Cirrhilabrus cf. lunatus.
This species is very closely associated with the preceding Cirrhilabrus brunneus, and the identical sympatric overlap throughout its range calls into question the validity of this fish attaining true species status. This sympatric overlay of two closely related sisters recalls the relationship between Cirrhilabrus lubbocki and C. flavidorsalis in the lubbocki group. Like those two, the relationship between Cirrhilabrus cf. lunatus and Cirrhilabrus brunneus are open to a few hypotheses, all of them contentious at best.
Sympatric speciation is rarely encountered in Cirrhilabrus, and when such examples arise, various theories and explanations can be put forth. The first possibility would be that C. brunneus diverged from the sympatric C. cf. lunatus through sexual selection. The need to differentiate itself through color change may serve as an advantage in mate selection, seeing as females of this group are all nearly identical in appearance. This sexual pressure may have catalyzed the evolutionary start of Cirrhilabrus brunneus.
Although both “species” are found in the same habitat, Cirrhilabrus brunneus is far scarcer and collected only in measly numbers. Cirrhilabrus cf. lunatus on the other hand is abundant where it is found. There are two possible explanations to explain this difference in relative abundance. It could be that these are two separate species which occupy different depth ranges – the rarer C. brunneus preferring deeper waters.
Or it could be that C. brunneus is actually the terminal male form of C. cf. lunatus. The sooty coloration has obvious similarities to the males of the Japanese C. lunatus, while C. cf. lunatus bears the color pattern typical of mature females in this species group.
The possibility of an earlier period of allopatry amongst these two forms shouldn’t be entirely discounted either. It could be that thousands of years ago, the two species swam in different ranges, but, with the removal of extrinsic forces which had previously isolated these two taxa, they have now expanded their ranges to be mutually sympatric. With such a long gap and opportunity to speciate, the two are now unable to hybridize back into a single homogenous taxon.
These theories and hypotheses are of course inconclusive without any extensive research or molecular comparisons between the two fishes. Tissue samples for both Cirrhilabrus brunneus and Cirrhilabrus cf. lunatus will be compared eventually, and hopefully this will shed some light on their relationship.
Cirrhilabrus cf. lunatus also swims with the “pintail” fairy wrasse in its range, where they hybridize to form a similar hybrid between the latter and Cirrhilabrus lunatus.
Cirrhilabrus squirei
Cirrhilabrus squirei is the final member of the lunatus group that sports the characteristic crescent tail. Cirrhilabrus squirei is one of the newest (second only to C. marinda) members of this genus, being officially described in 2014. Like C. johnsoni, C. squirei is currently thought to be allopatric with its related species.
Cirrhilabrus squirei is colored in the usual orange, with a network of reticulations over the body and face in a slightly darker shade. A series of yellow spots and stripes are present at the cheek and pectoral fin base, before converging into a broad yellow streak that runs parallel to the typical medial stripe. The characteristic dorsal and medial stripes of the lunatus group are well represented in this species; and are purple and complete.
The fins are hyaline yellow, with the dorsal and anal fins possessing a series of connected blue spots. The caudal fin is adorned with exceptionally long filamentous extensions, as well as having the usual cobalt highlights. Cirrhilabrus squirei is remarkably similar in appearance to Cirrhilabrus cf. lunatus, but differs primarily in having yellow fins.
Despite their great similarities, the widely separated populations of these two taxa suggest that these are reproductively isolated species. There is also a strong likelihood that the regions connecting the Australian C. squirei and the Indonesian C. cf. lunatus (Northneatern Papua New Guinea, the Solomon Islands, Vanuatu) will be found to have their own populations. This is a region with its own endemism, so any future discoveries may yet warrant the erection of yet another species within the lunatus group. The same can be said for more easterly regions, like Fiji, Tonga and Samoa.
Cirrhilabrus squirei is currently known only from the Great Barrier Reef and Coral Sea region, where its debut emergence in the aquarium scene first drew the attention of the scientific community. C. squirei was first collected by Cairns Marine, and the specific epithet “squirei” is Latinized and used in honor of Lyle Squire and the Squire family, founder of the preceding company. Another Coral Sea endemic that shares the same specific epithet is the endemic Rabaulichthys squirei.
C. squirei is deepwater, being found commonly at 130 ft. It frequents the same rubble dominated habitats and swims sympatrically with Cirrhilabrus laboutei, C. condei and C. bathyphilus in the Coral Sea.
Females bear the typical form for this group, being orange overall with a series of white stripes interlaced with white spots. This species is not as sexually dichromatic as the other members, and large females look superficially like the males but with subdued coloration and are without any embellishments on the caudal fins.
Taking into considering the ratio and scenario of C. brunneus to C. cf. lunatus, it is also possible that the full terminal coloration of Cirrhilabrus squirei is not yet known. Considering the infrequent offerings and sightings of this species, there is no way to know with certainty that a dark melanistic male form does not exist as well. Long term monitoring of aquarium specimens will help to answer this question – an example of the types of discoveries which home hobbyists can make to help advance our knowledge of reef fishes.
The species is available in the aquarium trade but only rarely, and commands a very high price. Cirrhilabrus squirei is the most expensive of all the lunatus group members.
The “pintail” fairy wrasse
The final member of the lunatus group is quite unlike any other, and is remarkable for possessing an unorthodox lancet shaped tail. The “pintail” fairy wrasse is a very apt name for this species, and although the caudal characteristics are quite unlike any of the lunatus group members, the rest of its features (along with female form, biogeography and propensity to hybridize with two other members) warrants its placement here.
Taxonomically this species is still undescribed, and has been assigned the tentative name of Cirrhilabrus cf. lanceolatus. Apart from the similarities in tail shape, this species is obviously different from Cirrhilabrus lanceolatus; the latter growing to over twice its size and belonging to a separate species group. For this reason we have decided against using that nomenclature for fear of confusion.
It does however bear some similarities to members of the lanceolatus group, especially in its juvenile form as well as the paired diagonal blue lines on the tail in adult males. Essentially, this species can be thought of as a “missing link” that bridges the morphological gap between the lunatus and lanceolatus groups.
In this exquisitely brilliant species, the strong charismatic tail and vibrant coloration immediately sets it apart from any other Cirrhilabrus. Although it adopts a wide range from Japan south to the Philippines, it cannot be confused with any other sympatric species in its range. The “pintail” wrasse is a variable orange to pink basally, with a series of yellow reticulations on its face and body. The same reticulations can be found in Cirrhilabrus squirei and Cirrhilabrus cf. lunatus.
The paired dorsal and medial stripes that are typical for the lunatus group are also very prominently and strongly displayed in this species. The median fins are elaborately spotted, and the dorsal fin is unique in possessing a large black spot beginning around the ninth dorsal spine.
The caudal fin is broad and rhomboidal, with the central rays extending to form a lancet shape. A pair of diagonal blue lines runs obliquely to the terminus, and the portions outside of this margin are clear. Like C. johnsoni and C. brunneus, the “pintail” wrasse possesses an epaulette that sits just below and slightly forward of the dorsal fin spot.
It is only in its nuptial display that this species’ beauty be truly appreciated. Males adopt a rose-colored chest and venter, intensifying into a rich magenta at the base of the anal fin. The paired caudal stripes (as well as body stripes) glow in a metallic blue and the epaulette in lilac. The dorsal spot also intensifies and becomes extremely prominent. The median fins do not become opaque in display, but intensify in color instead.
The “pintail” wrasse is found in Japan, where it swims sympatrically and in the same habitat with Cirrhilabrus lunatus. It can be found further south in the Philippines, where it also swims in tandem with Cirrhilabrus cf. lunatus. This species is able to form hybrids with both, which suggests not only the similarities between it and the other lunatus group members, but also between C. lunatus and C. cf. lunatus. It has not been documented to hybridize with Cirrhilabrus brunneus.
This species was known only from Japan, where its availability in the aquarium trade is highly sporadic, and the fish is reported to be extremely expensive. It was only recently that specimens became a regular export from the Philippines, which has helped to drive the price down. While by no means is the “pintail” wrasse a common find in aquarium stores (at least in North America), specimens can be acquired for a somewhat affordable price from retailers specializing in uncommon species.
Hybrids
Unlike the promiscuous Paracheilinus, hybridization appears to be a rare phenomenon in Cirrhilabrus. Despite the many sympatrically overlapping species in this populous genus, very few examples of hybrids have been documented. The lunatus group produces two examples, both of which have genetic input from the “pintail” wrasse.
The “pintail” wrasse hybridizes with C. lunatus in Japan where they overlap. Body patterning and expression of traits appears to be highly variable, with the resulting hybrid showing traits that skew to either parent. In the two images above, it’s clear that both show varying degrees of genetic expression that differ between them.
The individual in the first image shows a body pattern more reminiscent of Cirrhilabrus lunatus, with very dark fins and a strong yellow streak along its posterior lateral line. The dorsal and medial stripes that the “pintail” wrasse imparts are very weakly expressed here, and so is the dorsal epaulette.
The individual directly above shows a reverse, with a body pattern more reminiscent of the “pintail” wrasse. Here the dorsal and medial stripes along with the characteristic epaulette are strongly expressed. The yellow streak characteristic of Cirrhilabrus lunatus is suffused and indistinct. One trait that is always very clear and pronounced in such hybrids is the extreme double emargination of the tail.
In combination of a lanceolate and lunate caudal fin, the resultant hybrid always possesses a strong trident shaped tail, incorporating the traits from both parents evenly. Both specimens above possess a uniformly lunate tail with a strong extension of the central caudal rays.
This exact hybrid combination is also seen in the Philippines, but Cirrhilabrus lunatus is instead replaced by the enigmatic Cirrhilabrus cf. lunatus. Like its predecessor, the hybrid is variable and shows varying intensity of traits from both parents. However seeing as both the “pintail” wrasse and C. cf. lunatus are not that far apart in their body coloration, the variability of this hybrid is not as volatile as the Japanese form.
In the photo above of the same individual in stressed coloration, the dorsal spot of the “pintail” wrasse can be seen more prominently, albeit still heavily shaded by the dark suffusion imparted by C. cf. lunatus. Since both species possess the typical dorsal and medial stripes, the resultant hybrid likewise strongly displays this trait too. The characteristic double emarginated trident tail although not as strongly displayed in this individual, is still easily seen, especially in the first photo.
In its nuptial display below, remnants of the dorsal epaulette from the “pintail” wrasse can be seen, as well as the diagonal pair of blue lines on the caudal fin.
As should be clear by now, there are a great many questions remaining to be answered within the lunatus group. Only with extensive genetic study will we gain a better understanding for whether C. brunneus and C. cf. lunatus are a separate species. The “pintail” wrasse, despite being well known to divers and aquarists, is also scientifically unrecognized, though there is little doubt to its validity, and it is only a matter of time before it finally gets a name.
And, finally, how many more discoveries are yet to be made in the depths of poorly explored regions of the Indo-Pacific. Areas like the Eastern Indian Ocean, the Bismark Archipelago & Solomon Islands, and the Melanisian islands of Fiji, Tonga and Samoa are likely spots to find undiscovered taxa lurking in the depths.
[Update] The above image of a second Cirrhilabrus cf. lunatus x “pintail” hybrid was added post completion of this article. The new revelation of Cirrhilabrus lunatus in Aparri, Cagayan, Philippines, means that the other hybrid combination of C. lunatus x “pintail” may also exist in these waters, putting both hybrids in close sympatry.
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