RSS Fairy Wrasses: The bathyphilus group

MASA Admin

8 May 2007
Reaction score
The bathyphilus group, despite being a very small congregation, is by no means any less interesting or provocative compared to its congeners. In 1997 during the Indo-Pacific Fish Conference held in New Caledonia, five unidentified specimens of Cirrhilabrus were brought to the attention of Dr. John Randall by Michael Kulbicki. Because the specimens were long dead, and without the provision of their living coloration, the description was put on hold until proper materials could be procured.

A year later in 1998, Bronson Nagareda obtained a single individual of this species through a fish store in Honolulu. The specimen was traced back down the chain of custody and was eventually revealed to have been collected from an undisclosed location in the Coral Sea. Because of a superficial injury, Nagareda decided that it was best to first allow time for the fish to heal, but, to his dismay, it died a month later.

The bathyphilus phylogenetic tree. Photo credits in descending order: Fenton Walsh, Meerwasser Center Menzel, Dr. Hiroyuki Tanaka.

In 2001, aquarium fish collector Rene Jensen collected two specimens from Holmes Reef in the Coral Sea. Fenton Walsh recognized these as the same undescribed Cirrhilabrus that has since eluded description, and preserved them in formalin, but not before taking photos of them in their living state. In 2002, five years after the first specimens were made known to science, a name was finally put to this unidentified species. Cirrhilabrus bathyphilus became the fourty-second member of the genus, known from its type location of Holmes Reef, Coral Sea.

While the preceding events were simultaneously being carried out, two similar Cirrhilabrus coming out from the waters of Vanuatu were being traded in the aquarium hobby. The revelation of C. bathyphilus from the Coral Sea matched one of the Vanuatuan specimens, and the latter location served as a range extension. The other Cirrhilabrus remains distinctively different, and currently undescribed. In 2012, a third Cirrhilabrus of similar stature was described from Fiji and Tonga, and this is Cirrhilabrus nahackyi.

Key features of the bathyphilus group, with the inclusion of the female type. Photo credits: Fenton Walsh.

The bathyphilus group therefore contains two species, with a third phenotype in Vanuatu possibly attaining full species status with further studies. Members of this small group can be identified by a few characteristic traits. The tails are strongly double emarginated in males, appearing more prominent when the caudal fin is contracted. The dorsal fin is unusually tall, decreasing in height only very slightly as it tapers toward the posterior end. The dorsal fin is also always edged in black on the first and second spines, and in one species extends into a pennant. A black margin runs along the edge, and although highly variable, it is always present. Males adopt a rich sunset yellow ground coloration with a poppy-colored hood of varying extent (depending on the species). In C. bathyphilus however, this yellow is often obfuscated by an overlay of red from its “hood” markings.

The juveniles resemble those of the lunatus group and are tangerine, fading to yellow ventrally with a series of white lines interlaced with small white spots. The specific epithet “bathyphilus” is Greek for deep, and the members can be found in waters ranging from 100-700 ft.

The bathyphilus clade

Cirrhilabrus bathyphilus from Tanna, Vanuatu. Photo credit: Dr. Hiroyuki Tanaka.

The bathyphilus clade contains two members, one of which is very localized and endemic to a single island in Vanuatu (Éfaté Island); although it’s very likely it extends further north. It is currently known as Cirrhilabrus cf. bathyphilus, while its status as a species awaits further evaluation. The type species, C. bathyphilus, enjoys a larger range, spanning the Coral Sea and eastwards to Tanna Island of Vanuatu. The two forms are mutually exclusive and do not overlap and are separated by only 141 miles of ocean between them.

Proximal distance between the locations of both bathyphilus forms.

This presents one of the most unusual allopatric distributions of all the Cirrhilabrus species, in which two highly distinct phenotypes occur in such a narrow zone of separation within a single island chain. What forces might exist to act as a barrier between the two islands remains unclear, but it’s apparent for now that the two forms do not mix. The two phenotypes are very similar but can be differentiated based on the body coloration.

In Cirrhilabrus bathyphilus, its red hood bleeds gradually toward the caudal peduncle, obscuring the underlying yellow-orange coloration with a red suffusion. In its Éfaté Island sister, Cirrhilabrus cf. bathyphilus, the cranial hood is sharply distinct and is restricted to the anterior half of the body. Both variants are deepwater and rather uncommon but cannot be considered rare.

Cirrilabrus bathyphilus

Cirrhilabrus bathyphilus from Holmes Reef, Coral Sea. Photo credit: Fenton Walsh.

In Cirrhilabrus bathyphilus, the male is a rich sunset yellow fading to a lighter shade ventrally. The head is cloaked in a deep poppy red, which diffuses posteriorly along the length of the body. The extent of its cranial hood is rather variable, and occasionally, this suffusion is less homogenous, where a vestigial streak can be seen anastomosed to the caudal peduncle. Conversely, in extreme cases the suffusion is strong enough to totally obliterate the ground color, and the fish (as above) appears uniformly orange. In all cases, regardless, the diffusion of the hood is a key characteristic that separates this from the next “species”.

The pelvic fins are small, and as with the anal fin, are hyaline yellow. The latter is edged very marginally in purple. The dorsal fin is set further back and rather rectangular, with the anterior portion slightly taller than the posterior. The first two dorsal spines and the membrane within are always black, a trait all species in this group possess. The rest of the dorsal fin is variably colored in red, occasionally slated in a brilliant heliotrope purple (the extent of which depends on how terminal the males are). A thick black margin borders the outer edge of the dorsal fin, but this as well is very variable and either runs the entire length or is restricted to the posterior edge.

The caudal fin is strongly double emarginated, and is usually hyaline yellow. In excited or nuptial colors, it turns opaque crimson. The edge is bordered with a thick black margin, and the edges are suffused with the same brilliant heliotrope that washes the dorsal fin.

Cirrhilabrus bathyphilus in nuptial display. Photo credit: Peter Schmiedel.

Few photos of C. bathyphilus in spawning colors are available. Based on this single image from Peter Schmiedel, it appears that the posterior dorsum lights up in a silvery lilac blush during nuptial display. The tail intensifies slightly, while the rest of the body remains pretty much the same as in its resting phase. It is worthy of mention, however, that this is of a young male specimen. In larger, more terminal males, the caudal fin is expected to turn opaque crimson. The female form is rather uniform orange, with a series of white lines interlaced with spots, which is characteristic for the three species in this group.

Distribution ranges for both bathyphilus variants.

Cirrhilabrys bathyphilus is confined to the marginal edges of the Southern Pacific, where it ranges from Holmes Reef far west of the Coral Sea, east to New Caledonia and the southernmost tip of Vanuatu, in Tanna Island. Further north of Vanuatu, it is replaced by a similar but distinctively different variant. As mentioned before in the clade review, the two forms do not mix.

A group of Cirrhilabrus bathyphilus prior to export. Photo credit: Lawrence Sim.

C. bathyphilus is moderately uncommon in the aquarium trade, where it fetches a reasonably expensive price. They are most often exported out of Cairns and Vanuatu, where they are collected out of the Coral Sea and Tanna Island respectively. The photo above shows a bunch of males at a wholesaler in Singapore prior to export, and you can readily see the variability in coloration of this species. Notice the extent of the red suffusion along the length of its body. In some specimens a very distinct streak can be seen trailing off from the cranial hood, while in others, a very uniform and homogenous diffusion of red is displayed. The dorsal fin, as mentioned before, is rather variable, and here we see examples of males with the dorsal margin edged entirely in black, as well as individuals where the black edging is reduced to only the posterior.

Cirrhilabrus cf. bathyphilus

Cirrhilabrus cf. bathyphilus, male from Éfaté, Vanuatu. Photo credit: Fenton Walsh.

A stunning fish bearing the colloquial moniker of “hooded-fairy wrasse”, Cirrhilabrus cf. bathyphilus is truly deserving of its common name. This marvelous variant is colored essentially the same as the preceding, with the exception of its “hood”. In Cirrhilabrus cf. bathyphilus, the poppy-colored hood is never diffused over the posterior portion of its body and is restricted to the anterior by a very clear and abrupt demarcation.

Due to the absence of the red suffusion, the sunset yellow coloration is very obvious in this form and, together with its distinct hood, gives it a bi-colored appearance. A small orange rhombus is overlaid on each scale of the yellow posterior dorsum, resembling superficially a harlequin (or argyle) motif. The pelvic, caudal and dorsal fins are the same with C. bathyphilus, and are subjected to the same variations as well.

Cirrhilabrus cf. bathyphilus in nuptial display. Photo credit: Lemon TYK.

In the nuptial coloration of Cirrhilabrus cf. bathyphilus, the dorsal, caudal and facial hood intensifies into a deep, stunning crimson, occasionally sporting shimmery bursts of heliotrope. The pelvic and anal fins remain unchanged, and, as in the Australian bathyphilus, a silvery lilac blush develops over the posterior dorsum. The fins are held fully erect as the male maneuvers around a prospective female, and it is here where the unusually rectangular dorsal fin of this clade can be truly appreciated.

Cirrhilabrus cf. bathyphilus is currently known only from Éfaté Island of Vanuatu. This tiny locale is an unlikely place for endemism, especially for Cirrhilabrus – a genus with a relatively long pelagic larval stage. Strangely enough, this phenotype does not venture south, and just 141 miles away in that direction it is replaced by the preceding species. It is highly likely that C. cf. bathyphilus is found further north of Vanuatu, but the extent of its range is poorly documented due to its penchant for deep waters and the lack of underwater exploration in that area.

Cirrhilabrus cf. bathyphilus in nuptial display, showing the very tall and rectangular dorsal fin. Photo credit: Dr. Hiroyuki Tanaka.

This variant is harder to find in the trade than C. bathyphilus, but is a staple in all Vanuatuan shipments. Some of my fondest memories as a Cirrhilabrus nut involve this variant. I remember years ago when it first made its debut in Singapore, one of the LFS here opened through the night, allowing their customers to physically open the shipping boxes and handpick their choice wrasses on a first come first serve basis. Needless to say, the hooded wrasse was high on everyone’s bucket list. Being rather young then, it was intimidating standing amongst veteran reefers waiting for the shipping boxes to unload. As soon as they touched the ground, a flurry of enthusiasm ensued, like hyenas ripping apart the carcass of a gazelle.

Fervent ripping of boxes, coupled with desperate howls for the hooded wrasse echoed through the night. The less popular species like exquisitus and punctatus were set aside, followed by a sigh of frustration and disappointment. I remember sticking my hand into the box, randomly fishing for a bag, any bag as a matter of fact. Like a virgin lotto winner, there I was, gleefully smiling, much to the jealousy of everyone. A hooded wrasse! I didn’t even re-pack or re-oxygenated it. Took the shipping bag with the fish straight home there and then. Alas, this species is now rather staple and no longer as difficult to obtain.

The exact relationship between Cirrhilabrus cf. bathyphilus and C. bathyphilus remains unknown for now. Their allopatricity could at least warrant subspecific elevation for the former, but, without genetic comparison, nothing concrete can be said for the two.

Cirrhilabrus nahackyi

Cirrhilabrus nahackyi. Photo Credit: Dr. Hiroyuki Tanaka.

Cirrhilabrus nahacki is the final member of the bathyphilus group, and this is a fairly new Cirrhilabrus, being described as recently as 2012. Cirrhilabrus nahackyi is superficially similar to C. bathyphilus, but can be easily differentiated from the preceding two based on a few distinct morphological traits. In the males, the ground coloration is entirely luxurious yellow, with the red hood reduced to an orangey vestigial smudge on the nape and anterior dorsum. The dorsal fin is rather complicated, and the first two spines and membranes between are in the usual black for this species group. Terminal males are unusual in possessing a pennant on the first dorsal spine (this is seen elsewhere only in the distantly related rubriventralis group).

Male Cirrhilabrus nahackyi from Tonga. Photo credit: Dr. Hiroyuki Tanaka.

The dorsal fin is mottled greenish-yellow dusted in sooty black, giving it a dirty olive appearance. A variable series of hyaline windows in sky blue is sometimes seen on the anterior portion of the dorsal fin, close to the pennant. The posterior soft dorsal is edged marginally in black, and this may or may not make an oblique U-turn to the basal end. Within this black perimeter is a variable rainbow of red and yellow.

Cirrhilabrus nahackyi showing the variably colored dorsal fin. Photo credit: LiveAquaria.

The pelvic and anal fins are translucent yellow, which is purpled edged in the latter. The caudal fin is mostly rounded, rather than emarginated, and it has a very thin black margin posteriorly. This is decidedly different from the preceding two, where the tail is copiously edged in black.

No nuptial coloration of this species has been photographically documented online, so home aquarists are in a unique position to help further our understanding of C. nahackyi by sharing their own photos of its nuptial display. In the typical bathyphilus group fashion, the posterior dorsum should light up in a scintillating lilac, and the tail should intensify into a deep crimson.

A pair of Cirrhilabrus nahackyi. Photo credit: Dr. Hiroyuki Tanaka.

Cirrhilabrus bathyphilus is known only from Fiji and Tonga, where it occurs in similar rubble habitats on outer reef slopes that members of this genus are so fond of. It is likely to occur in Samoa, American Samoa, and Wallis & Futina. This species is slightly less deepwater than the other two members, and can be found between 100-160ft (35-50m). C. nahackyi was known from four type specimens provided by Tony Nahackyi, and the species was thusly named after him. Larry Sharron subsequently provided a fifth paratype from Tonga, and C. nahackyi was officially described in 2012 as the fourty-eighth member. Since then it has been making very sporadic appearances in the trade, proving it to be the least common of the bathyphilus group members.

Cirrhilabrus nahackyi in an excited state. Photo credit: Dr. Hiroyuki Tanaka.

The bathyphilus group is small and locally restricted, but certainly not without its fair share of uncertainties. Although all three members occupy allopatric distributions, the extremely close but disjunct proximity of Cirrhilabrus bathyphilus and Cirrhilabrus cf. bathyphilus within one island group is unusual. Without genetic studies, it is difficult to truly access the relationship between the two.

And finally, how many other members of the bathyphilus group are there left to be discovered? With their penchant for deepwaters, even the extent of their current distribution is plagued with uncertainties. This is also the final group of the first major clade on our proposed phylogenetic tree. Subsequent articles will feature group members with a different set of characteristics, such as larger and longer pelvic fins.
Readers also viewed:

Click here to read the article...
Top Bottom