DOTTYBACK DILEMMA – NEW OR NOT?

Pictichromis cf. paccagnellae from Central Sulawesi. Note the filaments on the upper and lower margin of the caudal fin. Photo by Scott W. Michael.

Pictichromis cf. paccagnellae from Central Sulawesi. Photo by Scott W. Michael.

Pictichromis paccagnellae from Northern Sulawesi. Photo by Scott W. Michael.

Pictichromis paccagnellae from Southern Sulawesi. Photo by Roger Steene.

Pictichromis paccagnellae from Papua New Guinea. Photo by Scott W. Michael.

Pictichromis coralensis from the Great Barrier Reef. Photo by Scott W. Michael.

Two different color variants of the newly described Pictichromis caitlinae.
Photos by Gerald Allen.

How about some more dottyback stuff fellow ichthyophiles– but these are a bit more colorful than the last one we examined! You may look at the photo at the top of the post and think “big deal” – it is a royal dottyback (Pictichromis paccagnellae). Or maybe it is the bicolor dottyback (P. coralensis)? Or maybe not? Compare it carefully to the photos of the two described Pictichromis spp. below it. You can see there are some disparities in coloration. (Also note that P. paccagnellae is quite variable in coloration as well.)

While all three species are bicolored – exhibiting the stunning magenta coloration on the fore portion of the body and yellow on the rear section - there are some subtle differences. Upon first examination , the most obvious difference between the mystery dottyback and the two described species is the margin of the magenta body section. In the first Pictichromis sp. the margin is strongly oblique, extending from the anterior portion of the dorsal fin (around the fifth or sixth dorsal spine) to the anal origin. In P. coralensis and P. paccagnellae, the margin tends to be straight or only slightly oblique, extending from the dorsal fin (in P. coralensis it can begin at around the 10th dorsal spine, while in P. paccagnellae it often originates between the seventh and eighth dorsal spine) to the ventral surface (it can end well in front of the anal fin or at its origin).

The pelvic fins of the mystery Pictichromis are entirely magenta. In many cases, but not in all locations, it is only the base of the pelvic fins that are magenta in Pictichromis paccagnellae (you can see that the pelvic fins can be entirely magenta in the photo of the Southern Sulawesi specimen above). Pictichromis coralensis may or may not have magenta pelvic fins.

Another difference is that the Central Sulawesi Pictichromis has filaments off the upper and lower edge of the caudal fin. This is most pronounced in larger individuals, but if you look at the top photo, you will see it in this medium-sized specimen. It also appears to have a slightly longer lower jaw than its relatives that juts out giving it a "Sammy Davis" junior appearance.

This individual fish, along with a number of other specimens, was sent to me by Ken Hyltoft, a fish enthusiast that works in the fish collecting business in Jakarta. Kenn knows his fish and found that this P. paccagnellae-like dottyback, that was being collected in Central Sulawesi, looked a little different than the described members of the genus. Pictichromis paccagnellae is apparently collected in the same area as this unusual dottyback, although according to the collectors that brought the fish to Kenn, the possible new species tends to be limited to greater depths (steep walls from 30 to 40 m).

Above you will also see a photo of a recently described Pictichromis from western New Guinea. It was described by Gerry Allen, Anthony Gill, and Mark Erdmann in 2008. It was named Pictichromis caitlinae. The color differences between this newly described species and the known species of Pictichromis is very obvious.

There was a time when subtle color differences between populations would have been classified as geographical variation. But since Kenn finds the “normal” P. paccagnellae with the unusual Pictichromis, it may be that the oblique-lined fish does warrant consideration as a distinct species? It will probably take analysis on the molecular level to determine for sure if this is a new species, but it was Kenn’s keen eye that has brought this unusual fish to light!

I want to thank Kenn for sending me the fish and Dave Palmer (Pacific Aqua Farms) and Dennis Reynolds (Aquamarines) for assisting in getting the fish to me!

Copyright (2008) Scott W. Michael

Reference:

Allen, G. R., M. V. Erdmann and A. C. Gill. 2008. A new species of Pictichromis (Pisces: Pseudochromidae) from western New Guinea with a redescription of P. aurifrons. aqua, International Journal of Ichthyology 13 ( 3-4): 145-154.