Cirrhilabrus exquisitus is an unusually widespread and variable species which appears to form a lineage alongside the scottorum and cyanopleura groups, with all three sharing characteristically mid-length pelvic fins. Unlike any other species of Cirrhilabrus, the Exquisite Fairy Wrasse has a range which extends from Africa to Japan and the French Polynesia, with readily discernible differences seen in several of these regions. It has long been recognized that this single taxon is likely a complex of several regionally endemic populations deserving of species status, and in this review we will work off that assumption.
Due to the lack of immediate relatives and information regarding the relationships between the various geographical forms, the Cirrhilabrus exquisitus complex will not be receiving a cladogram like the rest of the species groups. We have placed it as the basal-most sister lineage of cyanopleura and scottorum, as exquisitus has some important differences in its fin shape and coloration not seen in these other groups. Most important of which is the presence of a medial stripe to the dorsal and anal fins, versus having convoluted squiggles. Additionally, the caudal fin with heavy rows of blue spots is more akin to the more distantly related C. rubriventralis and C. temminckii. Further evidence supporting this clade is the occurrence of hybrids between C. exquisitus and C. melanomarginatus, possibly the only occurrence of hybridization between two distinct species groups in Cirrhilabrus.
This species and all its forms are highly charismatic, handsome and rather robust. It shares superficial similarities with its sister groups, such as medium length ventral fins, greenish base coloration and propensity to hybridize, but is distinctive enough and cannot be confused for any other species in this genus.
When discussing a complex with so many potentially undescribed species, it becomes particularly important to study the holotype material which taxonomically defines it. This specimen originated from collections made in Mozambique in 1957, making this the sixth oldest species currently recognized. And, while it appears likely that every major biogeographic region in the Indo-Pacific has its own “species”, only those from the African coastline should be thought of as the true C. exquisitus.
The exquisitus species complex members are very easily diagnosed from the rest of the Cirrhilabrus. Both oceanic forms possess very strongly double emarginated tails, with elongation of the caudal lobes and central rays, forming a strong “w” outline when contracted. This caudal shape is shared with the bathyphilus and marjorie groups, but both of these have much smaller pelvic fins and major differences in fin and body coloration, indicating that this is an example of convergent evolution. Their ventral fins are moderately long, but are never trailing. A large caudal peduncular spot is also mostly present, although this can be subjected to some variations. This is a rather unique feature that no other male Cirrhilabrus possess.
Both oceanic forms possess characteristic facial and pectoral stripes that are unique to this complex. In the facial stripes, a pair runs along the upper and lower orbital limits, diverging away as they pass the eye. The upper stripe connects either partially or completely with the dorsal stripe, and the lower stripe then connects to what is the start of the lower pectoral stripe, making an oblique diagonal along the outer fin base. A similar but shorter stripe runs parallel on the inner side.
In the Indian Ocean forms, however, these stripes are often obfuscated by the rosy face markings and are only noticeable during nuptial display. A lateral stripe is also seen in both oceanic forms; however, in the Indian Ocean variants, this stripe is always incomplete and reduced to the caudal region. This lateral stripe is very similar to that seen in Cirrhilabrus scottorum and members of the lunatus group, suggesting that this is an ancestral shared character (sympleisiomorphy) that is lost in various taxa. It is only in the cyanopleura group that this stripe is entirely lacking.
This Indian and Pacific Ocean rule makes a single exception for the Rowley Shoals phenotype, which, although inhabiting waters of the Indian Ocean, displays characteristics in correspondence to the Pacific Ocean forms. More of this will be touched upon later.
Juveniles and females are rather similar in all forms in both oceans. They are ferruginous overall, with a dull purple wash dorsally. A constellation of very fine spots arranged in rows recalls those of the cyanopleura and scottorum group, suggesting their possible phylogenetic relationship. The caudal peduncle is marked with a large black spot, and both juveniles and females possess a white tipped snout.
Unlike in the Pacific Ocean, the many subregions of the Indian Ocean show fewer clear phenotypic differences. Here, the males are fir green to dirty teal basally, and possess a few key characteristics. The face and pectoral regions are always masked in a dulcet rosy coif, with the resulting facial and pectoral stripes obscured. A stripe of similar hue is also always present on the dorsal fin base, and the lateral stripe is broken, incomplete and restricted to the caudal peduncular region. The dorsal fins may be blotched, but is never colored in red. The pectoral fins are hyaline and are never marked on the edges in red. The pelvic fins of the Indian Ocean forms often take on a dark blue or inky navy during nuptial display, which is almost always deep crimson or cadmium orange in the Pacific Ocean forms.
Cirrhilabrus exquisitus (Africa)
In the type representation of this species, C. exquisitus is uniformly dusky fir green throughout, except for its ventral region, which is very often stark white. The facial region is cloaked in a cherry pink coif, which extends rather extensively into the pectoral region, frequently passing the fin base. Because of this hood, the facial stripes are often marred and rendered innocuous. The dorsum is lined with a stripe of similar color, and this runs throughout the base of the dorsal fin. A lateral stripe is present, but this is always incomplete and broken, being restricted to the caudal peduncle. A large, conspicuous black spot sits just above the lateral stripe on the caudal peduncle.
The dorsal, pelvic, anal and caudal fins are chalky malt to transluscent green, and these, with the exception of the pelvic fins, are variably decorated with iridescent blue spotting. Not uncommonly, these spots may be superimposed against a more extensive black region so as to form a medial stripe. The medial stripe varies in its extent, and can be complete, broken or totally absent.
These dorsal and anal fin stripes are analogous to the medial stripes seen in most of the long-finned groups (which will be covered in future articles), and the presence of these markings foreshadow a shared characteristic between the two clades. The caudal fin is very strongly double emarginated and is linearly dotted on the edges in a series of blue spots. The outer margin is similarly spotted but in a vertical fashion.
In nuptial display, the dorsal fin lights up and turns bright malt to yellowish. A pair of saddles in white are prominently displayed, and these reach just shy of the dorsum. Fully terminal males at the peak of their excitation may also develop additional patches of bright white on the body, and an intense yellowing of the caudal fin. The rest of the body lightens slightly, and the pink coif is drastically reduced, such that the facial and pectoral stripes now become immediately apparent as they glow in a bright cyan. In the resting form, these facial and pectoral stripes are usually hidden under the copious pink shading on the face. The presence of the facial and pectoral stripes during this display is an important characteristic that unifies all variants in this complex. The dorsal stripe, lateral stripe and blue spots on the median fins likewise glow in cyan. During nuptial display, the caudal peduncular spot sometimes fades away, and the pelvic fins darken to an opaque navy.
The African Exquisite Wrasse is reported from the type locality of Mozambique, south to the Aliwal Shoals of South Africa and as far north as Kenya. To reiterate, these should be considered the only true C. exquisitus, with those collected elsewhere representing potentially undescribed species. Specimens from Africa (Kenya) are common in the aquarium trade and are moderately priced.
[Update] The two photos of African Cirrhilabrus exquisitus above displaying the prominent facial stripes were added post completion of this article. These stripes are often obscured by the red facial markings, but light up when they are excited or in nuptial display.
Cirrhilabrus cf. exquisitus (Seychelles)
Seychelles lies to the immediate east of Africa. Cirrhilabrus exquisitus is known from this region, but its presence here is poorly documented by divers and photographers. It appears there is no visible difference in coloration here, and the species adopts the same fir green body coloration with a cherry pink coif. Despite the phenotypic homogeneity, many other reef fishes (e.g. the Pseudojuloides cerasinus complex) with similar widespread ranges found in this region are recognized as distinct taxa. Thus, it should be presumed that there is genetic isolation in this population of C. cf. exquisitus which is not outwardly evident. This could be explained due to recent dispersal throughout the Indian Ocean, resulting in younger populations which have yet to recognizably diverge. Or it could be that the exquisitus complex is less inclined to develop phenotypic differences. What is ultimately needed is a thorough genetic study throughout its range to determine the relative age when these populations split from each other.
Its nuptial form from this location is not known, but, if there are any external differences to be found between these two regions, it would be most evident in the nuptial coloration. Aquarium collection takes place in nearby Mauritius, which is part of the same subregion as the Seychelles and any aquarists possessing an Exquisite Fairy Wrasse from this region should attempt to document their specimen.
Cirrhilabrus cf. exquisitus (Maldives, Sri Lanka and the Chagos Archipelago)
As previously mentioned, the Indian Ocean forms of this species are rather consistent in their appearance. This can be seen in the Maldivian representatives, where, superficially, no apparent differences can be observed in comparison to the African type. It appears that the Maldivian representation differs mostly in the extent of its red facial hood, but this may very well be a subject of individual variations.
Its nuptial display is very similar to that of the African form, and the same characteristics are observed. The pink coif fades to reveal the presence of the facial and pectoral stripes, which, together with the dorsal and lateral stripes, glow in a bright cyan. It is very interesting to note that in all the Indian Ocean forms these stripes are only revealed during nuptial display, when the pink facial markings are reduced. In certain individuals, an inkling of the ramifying pectoral scrawling can be seen, but these are often very vestigial and nowhere near as extensive as their Pacific Ocean counterparts. This, however, is strong evidence to suggest the relationship of the various forms throughout both oceans, and the likelihood that all these variants originated from a common ancestor.
Like the African forms, terminal males at their peak of excitation may develop white patches on the body in addition to the dorsal saddles. The caudal fin likewise has the potential to intensify to a deep yellow or orange. The pelvic fins darken to navy and become opaque.
This phenotype is commonly available to aquarist via Maldivian or Sri Lankan exports, where it, like its true African counterpart, is moderately priced.
Cirrhilabrus cf. exquisitus (Sumatra and the Andaman Sea)
Sumatra is a biogeographically important and interesting location. Like Bali, it sits in the middle of the Indian-Pacific Ocean divide. To its west lies the Indian Ocean, and to the east lies the Pacific. It is in this region where allopatric species from both sides mix in a very narrow strip. The presence of Cirrhilabrus exquisitus here is undeniable, but, unfortunately, there is minimal photographic documentation.
The above photo shows a single specimen from Lampung, Sumatra. Like the Indian Ocean forms, this form lacks a complete lateral stripe and the presence of any ramifying scrawling on the pectoral region. The usual fir green body and red markings are present; however, the latter is reduced dramatically to mere outlines of the usual facial and pectoral stripes. In this form, there appears to be no extensive hood obfuscating these stripes. The specimen above possesses red and yellow markings on the anal and dorsal fin. These are characteristics seen only in the Pacific forms, and it appears that C. exquisitus from Sumatra threads the line between both sides.
The specimen above shows an individual from Pulau Weh, Sumatra, in nuptial display. Notice the yellowing of the pelvic fins, which are characteristic of the Pacific Ocean forms. Again, the red facial markings are vestigial, but the other traits are more in line with the Indian Ocean forms. Take note of the lack of red or yellow markings in the fins of this specimen as compared to the previous one, and notice also the presence of the blue spotted saddles on the dorsal fin.
The phenotype of Cirrhilabrus exquisitus in Sumatra reveals a somewhat intermediate transition between the Indian and Pacific Ocean forms. Some inconsistent variability can be observed here, but not enough photographic documentation is present to make any conclusive hypotheses.
The Andaman Sea phenotype closely resembles the Sumatran form in having a very reduced red facial hood. The dorsal fin is also marked weakly with red and yellow, and the body is slated very lightly in a red wash. It is only this far East at the limits of the Indian Ocean that some divergence from the unwavering consistency in the standard phenotype is observed. Like the Sumatran forms, the Andaman Sea variants threads the Indian and Pacific Ocean divide, where it shows a slight mix of both major phenotypes. Notice the extensive prominence of the dorsal stripe, which, just on the opposite side in the Pacific, is very poorly displayed.
No nuptial coloration is documented, but it shouldn’t be too different from the Sumatran forms. In its courtship colors, the red facial markings are expected to fade away revealing the facial and pectoral stripes, and the dorsal fin should lighten to reveal two white blotches. There are no major fish collectors in the Andaman Sea area, making aquarium specimens very rare and limited only to local small-scale collectors. More photographic documentation is obviously needed to compare its similarities, or dissimilarities, with the other Indian Ocean variants.
[Update] The above image of C. cf. exquisitus from Sumatra was added post completion of the article. Notice the color median and pelvic fins, which are characteristics usually associated with the Pacific Ocean phenotypes. Note also the double parallel stripes bordering the pectoral fin base, a trait which is restricted to the Indian Ocean phenotypes. In the Pacific Ocean forms, this region is decorated instead with a network of blue ramifying scrawling. The Sumatran forms therefore show intermediate characteristics from both oceans.
Unlike the Indian Oceans forms, the Pacific representatives are wildly polychromatic, with most major biogeographical regions housing their own distinct forms. These forms may appear superficially similar in certain connecting regions, but their nuptial coloration reveals highly distinct polychromatism that suggest incipient speciation at work. Despite their differences, they all possess unifying characteristics that differentiate them from their Indian Ocean counterparts. The males are of the usual fir green but never possess any of the rose-colored facial and pectoral markings. Their facial and pectoral stripes are therefore clearly pronounced and well defined.
The pectoral region is also inscribed in a ramifying network of blue scrawling that converges to form a complete lateral line stripe. A dorsal stripe is sometimes present, but, unlike the Indian Ocean forms, this is usually weakly defined and most noticeable only during nuptial display. The dorsal and anal fins are decorated in red, with this patterning being important in diagnosing many of the regional populations. Pacific Ocean varieties have hyaline pectoral fins that are outlined along the edges in red. The pelvic fins of the Pacific Ocean forms often take on a deep crimson or cadmium orange during nuptial display, which is almost always dark blue or navy in the Indian Ocean forms.
Cirrhilabrus cf. exquisitus (Western Pacific)
This is the most widespread phenotype of the Western Pacific Ocean and is represented in Bali, Indonesia, Philippines and Palau. This form is particularly variable, but can be easily diagnosed based on a few key characteristics. In Cirrhilabrus cf. exquisitus from this region, males are a deep fir green, uniformly fading to a slightly lighter shade toward the ventral region. The face and pectoral regions are never marked with red, and the corresponding stripes are therefore clearly seen. A series of haphazard ramifying scrawling is present just above the pectoral fin, and these converge to form a complete lateral stripe that travels horizontally to the caudal peduncle.
The dorsal fin is green but edged copiously in scarlet on the outer edge. A narrow black medial stripe is variably present between the red and green demarcation, and this region is often neatly punctuated in metallic green or blue. The anal fin is green or yellow, and likewise edged copiously in scarlet. A variable black stripe is likewise present between the demarcation zone and is lined with blue spots, similar to that of the dorsal fin. The caudal fin is translucent green, strongly double emarginated and dotted generously in metallic blue. The pectoral fins have a thick, red margin, in contrast to the completely clear fins seen in Indian Ocean populations.
This phenotype is particularly mutable, and, in the most developed male specimens, an additional yellow saddle may be seen slated across the dorsum and dorsal fin. This is usually accompanied by an extensive expansion of a red ventral region, spreading up along the chest and cheeks. Together, these additional traits, if present, intensify greatly during nuptial display.
The nuptial form for this phenotype is particularly beautiful. The body lightens to a light, whitish-green on the anterior half while the posterior half darkens. All facial, pectoral and lateral stripes scintillate in an electrifying cyan, and the posterior ventral brightens to an intense scarlet. It is during nuptial display that the dorsal stripe may be seen, although this is usually weakly expressed and inconspicuous. The dorsal, anal, pectoral, pelvic and caudal fins burst in a fiery crimson, as the now Christmas-colored wrasse peruses its habitat.
This form is widely distributed throughout the Indonesian islands, from Bali to Bunaken, to the Banda Archipelago and Palau. It shows some variations throughout its range, but the most defining characteristic for this phenotype is quite obviously the extensive red markings on the median fins.
Cirrhilabrus cf. exquisitus from this region is commonly available in the trade. It is most frequently exported from Indonesia and Philippines, where it is reasonably affordable. This species, however, does not hold its colors quite as well as the African specimens, and the red markings are often lost after an extended period of time in captivity.
Cirrhilabrus cf. exquisitus (Australia and The Coral Sea)
C. cf exquisitus from the Australian and Coral Sea region closely resembles those from the preceding Western Pacific. The similarities it shares with the Indonesian form is uncanny, but Australian and the Coral Sea is another biogeographical hotspot for endemism, so, despite their phenotypic homogeneity, we must assume there is enough divergence to warrant recognition as a distinct species. This can be seen in other Australian taxa from different groups within the genus, where Cirrhilabrus beauperryi and Cirrhilabrus lineatus are distinct species, different from their Western Pacific counterparts of C. temminckii and C. rubrimarginatus, respectively.
The nuptial display for this phenotype is not known, but, as with many regional endemics, it should differ quite drastically from the other forms. As usual, this presents the home aquarist with a unique opportunity of documenting any nuptial activity, to help us in better understanding the biology of this fish. This phenotype is occasionally available from Australia and the Coral Sea, and is reasonably affordable.
Cirrhilabrus cf. exquisitus (Japan and Taiwan)
Japan is the northernmost limit for the Cirrhilabrus exquisitus complex, and, unsurprisingly, this region is home to yet another phenotypically unique form. The males here are of the usual fir green, lightening towards the ventral region in light green or white. The usual facial and pectoral stripes are present, as well as the pectoral scrawling, complete with an unbroken horizontal lateral stripe. The caudal peduncle is decorated with the usual black spot.
Like the Indonesian forms, males from this region are often variably decorated with a yellow saddle on the posterior dorsum. This may or may not be present, and is probably more prominent only in fully terminal males. The yellow or mustard saddle, if present, often encroaches well into the posterior dorsal fin, which is otherwise green, with a series of blue spots set against a medially placed black stripe. This stripe is never complete and rarely extents into the spinous anterior portion of the fin. The posterior soft dorsal is also often edged in red. The anal fin is similarly patterned, but ranges in coloration from green to yellow. Like the corresponding dorsal fin, it is often, but not always, edged on the outer margin in red.
The caudal fin is translucent and unmarked sans the usual metallic blue spotting and patterning. As with many of the Pacific Ocean varieties, the pectoral fin is hyaline but conspicuously edged on the outer margins in red. This phenotype is not particularly remarkable in its resting form, and the variability of the yellow saddle may prove somewhat inconsistent and confusing in their diagnostics. It is, however, immediately recognizable in its nuptial form where it displays certain characteristic traits unique to C. cf. exquisitus from this region.
At the peak of its nuptial coloration, the anterior portion of the body and dorsal fin lightens to a bright white, while the posterior soft dorsal region take on a characteristic dusky black. The rest of the body intensifies accordingly, and, if the male presents with any yellow coloration on the body, these too intensify in color. The facial, pectoral and lateral stripes scintillate in bright cyan, as do the pectoral scrawling and median fin spots. The dorsal stripe becomes evident during this display and scintillates in a similar shade of blue. The pelvic fins darken from translucent green to opaque yellow or orange, and the pectoral fin margins intensify to deep crimson.
The real defining characteristic for this phenotype is, as previously mentioned, the whitish anterior dorsal fin and contrasting black posterior. This is, unfortunately, only revealed in full prominence at the height of nuptial display. This form is documented throughout Central and Southern Japan, straying into Taiwan. Further down in the Southern Philippines and Indonesia, it is replaced by the preceding phenotype with red median fins.
Although there are semi-regular exports from Japan, this species is rarely targeted for collection due to its relatively low market value. If offered, its biology and husbandry should be similar to the regular forms currently available to aquarists.
Cirrhilabrus cf. exquisitus (Fiji)
Males from this biogeographic region are very dark hunter green, fading to a typically lighter shade near the ventral region. The usual pectoral scrawling and stripes on the face, pectoral and lateral regions are present. A large black caudal peduncular spot is likewise also present. Like the Japanese and Taiwanese forms, the males may possess some red markings on the posterior dorsal and anal fins, although these are subjected to individual variation and are never as extensive or prominent as with the Western Pacific forms.
The dorsal and anal fins are decorated with the usual black medial margin and blue metallic spotting. The dorsal fin occasionally sports yellow or orange transverse blotches on the posterior region. The yellow dorsum saddles or red body slating seen in the other variants are never present in Fijian males.
This phenotype is immediately recognizable in its nuptial display, and, like the preceding two variants, its pattern is in correspondence to its unique regional endemism. At the peak of its excitement, the body lightens to bright green, revealing a pair of saddles present on the posterior dorsum. These are usually light blue to white and are only evident during nuptial display. The facial, pectoral and lateral stripes scintillate in the usual cyan, and the peduncular spot disappears. The pectoral scrawling and spots on the median fins lighten in the same shade of blue as well. This phenotype shows the weakest development in its dorsal stripe, and, even in its excited state, the stripe is very poorly defined and mostly vestigial.
The chest intensifies to deep yellow and red, and so does the caudal, posterior dorsal, pelvic and pectoral fin margins. Another unique feature to this form (besides the dorsal saddles) is the whitening of the anal fin during display. Regardless of the original color, the anal fin always takes on a white to pale chalk color during its courtship display.
This phenotype is strongly represented in Fiji and probably around the surrounding islands, including Wallis and Futuna, Tonga, Tuvalu and Samoa. It is not uncommonly found in the aquarium trade from Fijian and Tongan exports, and the fish is only moderately expensive.
Cirrhilabrus cf. exquisitus (Melanesia – Vanuatu, Solomon Islands and Papua New Guinea)
The Melanesian islands of Vanuatu, the Solomon Islands and Eastern New Guinea are another region with high endemism, and it should come as no surprise that these waters are home to another distinctive variation of C. cf. exquisitus. Males from this region are a deep hunter green, much like those from Fiji. The usual body markings are present, but this phenotype very often possesses a rosy wash that may be seen slated across the body of terminal males, but this is never well defined or demarcated by contrasting lines as with the Indian Ocean varieties. A series of irregular magenta saddles are also often present along the dorsum. The dorsal and anal fins are rarely edged in red, but are instead yellow, with the usual black medial margin and metallic blue spots. The caudal and pelvic fins are variably translucent green to magenta, and the caudal peduncle is decorated with the usual black spot.
This form is distinctive enough to identify based on its resting coloration. Although the magenta wash on the body is not limited to this form, the dorsal saddles and yellow dorsal fins are, and this serves as a rather reliable diagnostic. Despite being rather well documented in the trade, very few photos of this form in its natural habitat are available. Likewise, very few, if any, photographic documentation of its nuptial coloration exists online. Again, this is a great opportunity for home aquarists to help in the understanding of these fishes. If you happen to have a photo of your Vanuatuan C. cf exquisitus in display, do let us know.
Cirrhilabrus cf. exquisitus (French Polynesia)
The French Polynesia is a poorly explored region with regards to the aquarium world, with just as little photographic documentation of the local reef life by divers. This is another potential area for endemic forms of Cirrhilabrus exquisitus, but only a few records of this fish exist from Taumotu. Males are of the usual ground color, complete with the standard markings, but they possess a large red blotch on the anterior portion of the body. This is reminiscent of C. scottorum from this region. The painterly color patterns in the exquisitus and scottorum groups aren’t seen to such an extent elsewhere in the genus, and this may be further evidence supporting their close relationship.
The pelvic, anal and caudal fins appear to be completely red, and so does the posterior soft portion of the dorsal fin. The spinous anterior portion is yellow. The females appear to be greenish, rather than the usual purple-slated, ferruginous orange. An indiscernible red wash can be seen suffused over the body, but, because the specimen is dead, it is unclear if the living coloration differs markedly or not.
Whether or not this Tuamotuan phenotype is representative of the entire French Polynesia is unclear. Based on the above specimens, however, it appears that this phenotype is at least consistent enough in that particular region. More documentation and specimens from the various island chains within the French Polynesia is needed to make a more definitive conclusion of the biogeographic endemism here. Until then, very little is known. On this topic, it is worthy of mention that the Marquesan Islands would be another possible locale for an endemic taxon, but Dr. Luiz Rocha (pers. Comm.) has failed to observe any specimens from the region during his dives there.
Cirrhilabrus cf. exquisitus (Micronesia)
Although this species is recorded from Micronesia, very little information regarding its distribution and prevalence is available. In an excerpt taken from Dr. John Randall, he describes, “The Marshall islands record is based on my observation of five females in 6m on the ocean reef at the southern end of Kwajalein Atoll about 300m east of the small boat passage (locally known as Czar Pass). The fish were wary and could not be approached for a good underwater photo. A distant photo was taken of one individual which is identifiable as the species; it is on file at the Bishop Museum.”.
Until that photo is revealed, it is unknown to us whether or not the Micronesian population possesses any phenotypically unique features. Genetic variation is, as usual, to be expected. Dr. John Randall’s eyewitness of the species from this locale points to the presence of females, but made no mention of the males. Differences in the female form may not be as discerning as those of the males, but without any photographic records, not much can be said for now. Brian Greene also reports this species as being present in “Kiritimati, Kwajalein, Majuro, Pohnpei and even Palmyra Atoll”. It was the only Cirrhilabrus species he recorded in Palmyra.
Despite the many eyewitness accounts of this species from the Micronesian region, we have been unsuccessful in tracking down a photograph proving this. This is, surprisingly, proving to be one of the most elusive Cirrhilabrus.
Cirrhilabrus cf. exquisitus (Western Australia)
The Rowley Shoals in Western Australia is home to a few endemic labrids, where Cirrhilabrus is well represented by C. randalli and C. morissoni. The rather unusual Coniella apterygia (which we previously discussed as a modified Cirrhilabrus) is also found nowhere else on Earth but here. Not surprisingly, a unique form of the ubiquitous Cirrhilabrus exquisitus is documented to swim in these waters.
The males here resemble the Vanuatuan phenotype very closely, having the same red saddles on the dorsum. The dorsal fin, however, is more extensively edged in red than the latter. The usual markings and stripes are otherwise unchanged.
Interestingly, the nuptial forms resemble the Fijian phenotypes rather closely with the development of the dorsal saddles and chest coloration. The dorsal fin is, however, more extensively edged in red, and the body develops yellow markings medially. The anal fin is rather variable and, based on these photos, appear to range from solid white to red-edged. Both pelvic fins and caudal fins intensify to opaque red.
This phenotype is restricted to Rowley Shoals and possibly Hibernia Reef in Western Australia. The biogeographical location of this area is extremely intriguing; although technically located in the Indian Ocean, this phenotype displays very diagnostic characteristics in line with the Pacific Ocean forms. The lack of red facial markings, the presence of the ramifying pectoral scrawling and red trimmings on the pectoral fins are all absent in the Indian Ocean specimens.
This is irrefutable evidence that the Rowley Shoal endemics were derived from Indonesian immigrants that subsequently speciated due to allopatric isolation. The same can be seen in C. randalli and C. morissoni, which likely arose from the insertion and subsequent isolation of Indonesian members from the solorensis and rubriventralis groups, respectively. As such, this phenotype in the Northwestern Australian region (as well as Cocos-Keeling and Christmas Islands) is the only exception of the Indian Ocean rule, where it displays traits in line with the Pacific Ocean forms.
Although no hybrids have been documented in the Cirrhilabrus exquisitus type from the Indian Ocean, the same cannot be said for the Pacific. The Japanese phenotype of C. exquisitus has been documented to hybridize with C. melanomarginatus. Curiously, despite the rather large overlap of the two, no hybrids have been documented to exist outside of Japan. They should, in theory, hybridize on the edges of C. melanomarginatus’ range, where it is less abundant.
It is also noteworthy that Cirrhilabrus scottorum, a very close relative of C. melanomarginatus, overlaps with C. exquisitus throughout its range, but no hybrids of the two have been documented. It can be argued that the lack of evidence supporting hybridization can be attributed to the relatively unexplored regions by field photographers, but, conversely, the same region experiences rather frequent collection, way more than in Japan, where C. melanomarginatus x C. exquisitus is documented.
The hybrid above shows a fish with a fascinating mélange from both parental phenotypes. In both species, the ground coloration is green, so a rather uniform shade of the same hue is to be expected. What is immediately apparent, however, is the double-emarginated tail of C. exquisitus peeking through, coupled with the banding and spotting on the anal fin (two traits that are absent in C. melanomarginatus). The heavily blackened dorsal fin also suggests genetic input from C. melanomarginatus, and, although C. exquisitus shows regional variants with a black dorsal fin, it is never complete or so extensive.
This is some of the strongest evidence supporting the closeness of the scottorum group with the Cirrhilabrus exquisitus complex. We’ve also seen how the Cirrhilabrus exquisitus complex is very superficially similar to the cyanopleura group, especially in the female and juvenile forms.
The numerous phenotypic variations expressed by this complex offers a fascinating look into the polychromatism of reef fish. The complex as a whole is no doubt undergoing speciation as we speak, the reason for which is probably attributed to sexual selection. Most of the major differences that we’ve observed are those that are featured only during nuptial display, which is very much in accordance to sexual pressure and the need for male recognition. It is quite likely that the evolutionary process of natural selection will yield even greater significant differences down the line, as the members of the exquisitus complex continue to speciate in their opposing directions.
This marks the end to one of the most fascinating and confusing species of fairy wrasse. It concludes our discussion on the second major lineage within Cirrhilabrus. In future articles, we will finish our phylogenetic review of the genus by discussing those groups with the most highly-elongated pelvic fins, as well as the very strange Cirrhilabrus laboutei.