Korean Prickleback

description

Description. Body and head greatly compressed and elongated (Fig. 2). Eyes located dorsolaterally on head, snout short and rounded, lips thick. Dorsal contour of head almost straight (Fig. 3 A – C). Teeth small, but sharply conical, maxillary teeth in two rows but multiserial anteriorly. Vomerine and palatine teeth conical, multiserial. Mandibular teeth in two rows at anterior end, but followed by a single row of teeth (Fig. 4). Dorsal-fin origin above the middle of pectoral fin. Dorsal and anal fins confluent with caudal fin without any notches. Pectoral and caudal fins rounded. Pelvic fin absent. Body with embedded small cycloid scales. Cephalic-sensory canals and pores weakly developed. Supraorbital canal (SPO) connected to interorbital canal (ITO); posterior postorbital canal (PPO) connected to 2 nd lateral line; occipital canal (OC) connected to 1 st lateral line (Fig. 3 A` – C`). Lateral line system forming complicated network: first lateral line (upper most) extending below dorsal contour of body to caudal-fin base; second running below first lateral line in parallel and connecting with first lateral line near caudalfin base; third showing zigzag form from pectoral-fin base

A new species of prickleback, Dictyosoma tongyeongensis (Perciformes: Stichaeidae) from the South Sea of Korea

diagnosis

Diagnosis. Dorsal-fin rays LVIII – LXII, 8 – 10; anal fin rays II, 45 – 47, total number of vertebrae 70 – 74; dorsal contour of head almost straight; pelvic fin absent; 3 rd lateral line extends with zigzag from pectoral fin to caudal-fin base. No blackish-brown blotches on the head; a single white oblique band on cheek; many small pale brown rounded spots present at the caudal region.

A new species of prickleback, Dictyosoma tongyeongensis (Perciformes: Stichaeidae) from the South Sea of Korea

discussion

Remarks. Our six specimens were identified to the genus Dictyosoma by the following morphological combinations, suggested by Yatsu et al. (1978) and Hatooka (2002): 1) lateral line system forming a complicated network, 2) pelvic fin absent or rudimentary, 3) skin embedded with small cycloid scales, and 4) dorsal and anal fins confluent with caudal fin without any notches. The genus Dictyosoma is characterized by the lateral line system, which consists of three or four complicated lateral lines on each side of body. In particular, species can be classified by the absence or presence of the 3 rd lateral line. D. tongyeongensis is more similar to D. rubrimaculatum than to D. burgeri in having the 3 rd lateral line complete (Fig. 4). We also found differences in the dorsal contour of head between D. tongyeongensis and the two other congeneric species. The dorsal contour of the head of D. tongyeongensis is almost straight, while that of both D. burgeri and D. rubrimaculatum is gently convex (Figs. 3 B, C, 7 A – C). Yatsu et al. (1978) documented that D. burgeri and D. rubrimaculatum have a distinctive blackishbrown blotch on the upper region of the opercle. In contrast, D. tongyeongensi

A new species of prickleback, Dictyosoma tongyeongensis (Perciformes: Stichaeidae) from the South Sea of Korea

etymology

Etymology. The specific name, tongyeongensis, refers to the name of type locality (Tongyeong).

A new species of prickleback, Dictyosoma tongyeongensis (Perciformes: Stichaeidae) from the South Sea of Korea