A new species of Careproctus (Cottoidei: Liparidae) from the Sea of Okhotsk and a redescription of the blacktip snailfish Careproctus zachirus

A new snailfish, Careproctus shigemii, is described on the basis of three specimens collected in the southern Sea of Okhotsk, off Hokkaido, Japan. The new species has previously been confused with Careproctus zachirus Kido 1985, known from the Aleutian Islands, eastern Bering Sea, the Pacific Ocean off southeastern Kamchatka and the northern Kuril Islands, and the southern Sea of Okhotsk off Hokkaido, Japan, because of their similar appearance, including a noticeably elongate pectoral fin extending beyond the anal-fin origin, the gill slit entirely above the pectoral fin, no opercular flap projection, one suprabranchial pore, and trilobed teeth. However, C. shigemii is clearly differentiated from C. zachirus in having dorsal and anal fins margined with black (vs. white margined dorsal and anal fins with a black submarginal band), and a black caudal fin (vs. pale pink caudal fin), when fresh. Careproctus shigemii differs additionally from C. zachirus in having the cephalic pore pattern 2-6-6-1 (vs. 2-6-7-1), 30–35 pyloric caeca (vs. 20–31), and a shorter pectoral fin lower lobe, 8.2–9.9% SL (vs. longer lobe, 15.9–25.6% SL). A large sequence divergence between C. shigemii and C. zachirus (0.028 in uncorrected p-distance) in the DNA barcoding region (COI) also supports the validity of each species. A redescription of C. zachirus is also provided on the basis of the holotype, paratypes and non-type specimens.