PHOLIDICHTHYS ANGUIS, A NEW SPECIES OF PHOLIDICHTHYID FISH FROM NORTHERN-TERRITORY AND WESTERN-AUSTRALIA

Pholidichthys anguis is only the second species known in the family Ph olidichthyidae. It differs from P. leucotaenia in having 87-98 dorsal- fin rays (vs. 66-79), 70-81 anal-fin rays (vs. 49-62), 90-101 total ve rtebrae (vs. 71-79), a more slender body, and a shorter head and maxil lary. In addition, the color pattern of juveniles (similar to 50-103 m m SL) differ in having the depth of the slender dark stripe on midside at vertical from anal-fin origin about 1 mm, usually much less (vs. d epth 2.5-3.3 mm). Study of whole specimens and skeletal preparations o f P. anguis indicates that the species exhibits the same familial spec ializations as P. leucotaenia. The two species are distributed allopat rically. We hypothesize that the common ancestor of the two species of Pholidichthys had a Tethyan distribution exclusive of Australia-New G uinea (ANG). When ANG collided with SE Asia, the ancestor invaded ANG. During a subsequent interglacial period, ecological factors contribut ed to the isolation of the Australian portion of the ancestral populat ion from the New Guinea portion, and permitted divergence of the isola tes.