Revision of the Tubenose Poacher Genus Pallasina Cramer (Perciformes: Cottoidei: Agonidae)
Species of the tubenose poacher genus Pallasina are assessed following examination of over 450 specimens from throughout the Pacific Rim, from the coast of California to the Chukchi Sea and Sea of Japan. The results presented here, including both morphological and mitochondrial DNA datasets, indicate that three species of Pallasina occur in the North Pacific and surrounding seas. Pallasina aix is found in the eastern North Pacific from California to southeast Alaska and in the Salish Sea. It has the shortest barbel of the three species and a unique haplotype in the mitochondrial COI region. Pallasina barbata is the most widespread species, ranging from the Gulf of Alaska to the Chukchi Sea and west to northern Japan. It is distinguished by having a moderate barbel length and can be separated from the other two species using a variety of meristic characters. Pallasina eryngia is found only in the central and northern Japanese Archipelago, and it is a relatively deep-water species. It is distinguished by having a long barbel, as well as relatively high counts of vertebrae and dermal plates. This study presents redescriptions of all three species and a key to their identification.
Dermal plates in the prepelvic region of Pallasina aix. Rows with a single median plate are represented with a “1,” while rows with paired medial plates are represented with a “2.” Thus, the specimen illustrated here has five prepelvic plate rows, with a prepelvic plate count of “1,2,1,1,2.”
Plots of principal component (PC) scores for (A) meristic PC1 vs. meristic PC2, (B) morphometric PC2 vs. morphometric PC3, and (C) meristic PC1 vs. morphometric PC2 for Pallasina aix (open squares), P. barbata (dark circles), and P. eryngia (open triangles).
Plot of head length vs. barbel length for examined specimens of Pallasina aix (open squares), P. barbata (dark circles), and P. eryngia (open triangles).
Plot of linear discriminant (LD) scores from discriminant analysis of species of Pallasina: P. aix (open squares), P. barbata (dark circles), and P. eryngia (open triangles).
Geographic distribution of specimens examined and haplotypes for sequenced specimens of Pallasina: P. aix (dark squares), P. barbata (dark circles), P. eryngia (dark triangles); Haplotype 1 (open squares), Haplotype 2 (open circles), and Haplotype 3 (open triangles).
Type specimens of species of Pallasina: (A) Pallasina aix, CAS-SU 5040, holotype, 103 mm; (B) Pallasina barbata, NMW 12103, lectotype, 117 mm; (C) Pallasina eryngia, CAS-SU 20165, holotype, 164 mm.
Illustrations of type specimens of Pallasina: (A) Pallasina aix (after Starks, 1896); (B) Pallasina barbata (after Steindachner, 1876); and (C) Pallasina eryngia (after Jordan and Richardson, 1907).