A
juvenile Calloplesiops argus, the finespotted
comet. This individual is approximately 8 cm (3.5
inches) in length. Photo: Scott Michael
In Volume 1, issue 9 of Advanced
Aquarist I wrote an article on the husbandry of the
comet (Calloplesiops altivelis). In that article, I
briefly discussed the taxonomic status of the finespotted
comet (Calloplesiops argus). I concluded, based
primarily on the observations of Kuiter and Debelius (1984)
and Kuiter (2000), that this species is synonymous with C.
altivelis.
In this short article I would like to
re-examine the taxonomic status of C. argus.
One
or Two Species?
There
has been some controversy over the number of species in the
genus Calloplesiops. Originally two species were
recognized in the genus. The second species, the finespotted
comet (Calloplesiops argus), was thought to be
distinguished from C. altivelis by its coloration and the
size of the pelvic fins (when folded down, they extend back to
about the middle of the anal fin in C. argus). (There may
be other meristic differences between the two “species” as
well.) The spots on C. argus are much smaller, the white
patch on the end of the tail is more larger, and there are blue
lines on the pelvic fins and median fins.
Calloplesiops argus.
Photo: Julian Sprung
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But
Kuiter and Debelius (1994), and more recently Kuiter (2000),
reported that these chromatic differences and changes in the
relative size of the pelvic fins were simply related to the
fish’s age and size. They suggest that as C. altivelis grows
larger, the spots on the head and body become smaller and more
numerous, the spots on the median fins elongate and join, and the
white patch becomes more pronounced at the tip of the tail. The
pelvic also become proportionally larger. Kuiter (2000) reports,
having observed the two color forms in close proximity to one
another on a reef slope off the island of Flores, Indonesia, the
following: The C. argus phase was approximately 16 cm (6.2
inches), while the C. altivelis was about 12 cm (4.7
inches). This apparently catalyzed him to conclude that C.
argus is simply the larger (possibly male) color form of C.
altivelis.
While
it is true that juvenile comets have much fewer, larger spots
than the adults, there is now increasing evidence that supports
the hypothesis that C. argus is a valid species. For
example, C. argus (or the C. argus phase) is
rarely seen in the aquarium trade or in nature. Even though
large, adult comets of the C. altivelis-type are quite
frequently collected. If C. argus is simply the adult
color form of C. altivelis why is it so infrequently
collected or observed in nature? Also, many people have kept
individual comets in their aquariums for numerous years. Even
so, I have yet to see or hear from a fellow aquarist that they
have seen a comet change from the C. altivelis to the C.
argus color phase. Calloplesiops argus also has a
much more limited distribution, having only been reported from
Indonesia and the Philippines.
Calloplesiops
altivelas. Photo: Julian Sprung
But maybe the most
important piece of evidence supporting the validity of C. argus is
a specimen that was recently sent to me by my friends Dennis and Erik
Reynolds at Aquamarines (a wholesale fish supplier). They sent me
a perfect example of the finespotted comet that was only 7 cm (3.5 inch)
long! That is much smaller than the largest C. altivelis color
phase that I have seen. From these observations, I would suggest that C.
argus is actually a valid species. It appears to be quite rare. I
have only seen three C. argus in my lifetime (all in the aquarium
trade) and Erik Reynolds told me that they see about three C. argus a
year at the Los Angeles wholesalers they frequent.
An
adult C. argus. Note the long pelvic fins, the head
profile, and the numerous spots. Photo: Scott Michael
An
adult Calloplesiops altivelis. Compare with the adult C.
argus. Photo: Scott Michael
Recently
I spoke with reef specialist Julian Sprung who told me he is sure that C
argus is a valid species. He too has seen a number of small
individual C. argus. He also points out that C. argus has
a steeper profile and is more laterally compressed than C. altivelis.
In Michael (1991), I stated that “Occasionally,
you might encounter larger specimens that displayed
characteristics of both color phases.” I suggested
that these were probably individuals that were
changing from the C. altivelis and C. argus
color phases. I began reflecting on this statement and
looked back on my notes on this fish. While I have
seen C. altivelis with more spots that were
more intermediate in size, as well as individuals with
more blue on the median fins than the “normal” altivelis,
my conclusions that these were individuals
transforming from the C. altivelis to C.
argus color phase may have been unjustified. It is
equally likely that individuals exhibiting an
intermediate color phase are C. altivelis x C.
argus hybrids.
REFERENCES
Kuiter,
R. H. 2000. Fishes of Indonesia. CD ROM.
Kuiter,
R. H. and H. Debelius. 1994. Southeast Asia
Tropical Fish Guide. Ikan, Frankfurt, Germany, Pp.
321.
Michael,
S. W. 1991. A guide to the comets (genus Calloplesiops).
Sea scope 8 (Spring):1,2.
