Stiphodon multisquamus Wu and Ni, 1986

Kunishima, Taiga, Tanaka, Ryosuke, Hirashima, Kentarou & Maeda, Ken, 2021, Northernmost Record of Stiphodon multisquamus (Gobiiformes: Oxudercidae) Based on a Specimen from Wakayama, Japan, Species Diversity 26 (1), pp. 37-41 : 38

Stiphodon multisquamus Wu and Ni, 1986 ( Figs 2 , 3 )

Material examined. WMNH-PIS10942 , female, 29.4 mm SL, 1 November 2018 .

Description. The counts and morphometric measurements are provided in Table 1. Body elongate, cylindri-

cal anteriorly and somewhat compressed posteriorly. Head somewhat depressed with a round snout protruding beyond the upper lip. Anterior nostril tubular and short, posterior nostril not tubular. Mouth inferior with the upper jaw protruding beyond the lower jaw. Upper lip thick and smooth with a small medial cleft. Premaxillary teeth 37. Dentary with 35 horizontal teeth and one canine-like symphyseal tooth. First dorsal fin with six spines and second dorsal fin with one spine and nine soft rays. Anal fin with one spine and 10 soft rays. Caudal-fin rounded with 17 segmented rays, including 13 branched rays. Pectoral fin with 16 soft rays. Pelvic fin with one spine and five soft rays; right and left fins joined together to form a cup-like disk with a frenum. Ctenoid scales covering tail and lateral and dorsal sides of the posterior trunk. Cycloid scales covering the belly, lateral side of the anterior trunk, nape, occipital region, first and second dorsal-fin bases, anal-fin base, caudal-fin base, and proximal part of the caudal fin. Scales on the occipital region and nape notably smaller than the lateral scales on the trunk and tail ( Fig. 3A ). Cephalic sensory pore system with A′, B, C, D(S), F, H′, K′, and L′ in the oculoscapular canal and N′ and O′ in the preopercular canal. Number of vertebrae 10+16 (abdominal and caudal vertebrae). Urogenital papilla plumper and rectangular.

Coloration of the preserved specimen. Background of body whitish; blackish longitudinal stripe extending from the snout to the pectoral-fin base through the suborbital region; stripe continuing from behind the pectoral-fin base to the caudal-fin base through lateral midline. Dorsum dusky with two whitish transverse bars on the occipital region and nape ( Fig. 3A ). Anal-fin rays translucent with black markings near their translucent tip ( Fig. 3B ). Caudal-fin translucent with some black spots along its middle rays. Pelvic-fin translucent without pigment.

Habitat. Stiphodon multisquamus was collected in a riffle with substrates composed of loose cobbles below a tidal weir, located approximately 5 km upstream from the river mouth. The water depth was about 20–30 cm when the specimen was collected in this study. The sampling site was considered to be influenced by tidal fluctuation, but no salinity was usually detected. There are two fish ways in the tidal weir on both sides of the river. It cohabited with other gobies, including Rhinogobius nagoyae Jordan and Seale, 1906, Sicyopterus japonicus (Tanaka, 1909) , and Tridentiger brevispinis Katsuyama, Arai, and Nakamura, 1972 , but no other specimen of the genus Stiphodon has been found so far.

Figures

Fig. 2. Photographs of Stiphodon multisquamus (WMNH-PIS10942, 29.4mm SL) collected from Arida-gawa River, Wakayama Prefecture, Japan, on 1 November 2018. A, Specimen, preserved, lateral view (above) and dorsal view (below); B, specimen, alive.

Fig. 3. Preserved specimen of Stiphodon multisquamus (WMNH-PIS10942, 29.4mm SL). A, Anterior half of the body in dorsal view; B, enlarged photo showing black pigments on anal-fin rays (see arrows).