Friday, July 15, 2016

[Ichthyology • 2016] Mulloidichthys flavolineatus flavicaudus • A New Subspecies of Goatfish (Perciformes, Mullidae) from the Red Sea and Arabian Sea

 Mulloidichthys flavolineatus flavicaudus 
 Fernandez-Silva & Randall, 2016 
 DOI:  10.3897/zookeys.605.8060

The number of goatfish species has increased recently, thanks in part to the application of molecular approaches to the taxonomy of a family with conservative morphology and widespread intraspecific color variation. A new subspecies Mulloidichthys flavolineatus flavicaudus Fernandez-Silva & Randall is described from the Red Sea and Arabian Sea, including Socotra and Gulf of Oman. It is characterized by a yellow caudal fin, 25–28 gill rakers, and 37–38 lateral-line scales and it is differentiated from nominal subspecies M. flavolineatus flavolineatus by 1.7% sequence divergence at the mitochondrial cytochrome b gene. The morphometric examination of specimens of M. f. flavolineatus revealed variation in head length, eye diameter, and barbel length, in western direction from the Hawaiian Islands, South Pacific, Micronesia, and the East Indies to the Indian Ocean. The population of Mulloidichthys f. flavicaudus subsp. n. in the Gulf of Aqaba differs from that of the remaining Red Sea by shorter barbels, smaller eyes, shorter head, and shorter pelvic fins. We present a list of 26 endemic fishes from the Gulf of Aqaba and discuss the probable basis for the endemism in the light of the geological history of this region.

Keywords: cytb, marine fish, glacial refugia, phylogeography, taxonomy, vicariance

Figure 4. Underwater photographs of Mulloidichthys flavolineatus flavicaudus subsp. n. from Dahab in the Gulf of Aqaba.
Photo by Sergey V. Bogorodsky. 

Diagnosis: Body elongate, the depth at first dorsal-fin origin 4.1–4.5 in SL; head moderately compressed, the length 3.0–3.3 in SL; snout long, slightly blunt. Barbels usually not reaching a vertical at posterior margin of preopercle, their length 4.1-5.0 in SL. Eye diameter 10.3–13.5 in SL. Pectoral-fin rays 16–18. Gill-raker counts 25–28 (usually 26 or 27); lateral-line scales 37–38. Caudal fin yellowish to yellow. [Diagnosis based on the Red Sea proper population, i.e. excluding the Gulf of Aqaba, see remarks].

Etymology: Mulloidichthys f. flavicaudus subsp. n. is named in reference to the yellow color of the caudal fin, in contrast to the whitish gray color of the caudal fin of M. f. flavolineatus.

Distribution: Mulloidichthys f. flavicaudus subsp. n. is restricted to the NW Indian Ocean biogeographic province, where it ranges from various locations in the Red Sea (including the Gulf of Aqaba), the Gulf of Tadjoura, the Gulf of Aden, and Socotra (Fig. 9). M. f. flavicaudus subsp. n. has extended its range to Oman (Fig. 11) and probably to the Maldives (Fig. 12), where it has encountered the western distribution of M. f. flavolineatus. Underwater photographs of fish with yellow and gray caudal fins suggest overlap and interbreeding by the two subspecies. Carpenter et al. (1997) included M. flavolineatus in their catalog of fishes of the Arabian Gulf. They did not cite any voucher specimens, and the photo they used is from Mauritius.

Figure 7. School of Mulloidichthys flavolineatus flavicaudus subsp. n. at Eilat, Gulf of Aqaba.
Photo by John E. Randall.  

 Iria Fernandez-Silva, John E. Randall, Daniel Golani and Sergey V. Bogorodsky. 2016. Mulloidichthys flavolineatus flavicaudus Fernandez-Silva & Randall (Perciformes, Mullidae), A New Subspecies of Goatfish from the Red Sea and Arabian Sea. ZooKeys. 605: 131-157. DOI:  10.3897/zookeys.605.8060