Rhinogobius yaima Suzuki, Oseko, Kimura & Shibukawa, 2020
Rhinogobius yaima
photo by Maeda et al., 2021

Family:  Gobiidae (Gobies), subfamily: Gobionellinae
Max. size:  6.6 cm SL (male/unsexed); 5.03 cm SL (female)
Environment:  demersal; freshwater
Distribution:  Asia: Japan, Ryukyu Is.
Diagnosis:  Dorsal spines (total): 7-7; Dorsal soft rays (total): 7-9; Anal spines: 1-1; Anal soft rays: 7-8; Vertebrae: 26-26. This species is distinguished from its congeners by the following characters: head depressed, its maximum depth 65.5-71.6% of its maximum width; the body and caudal peduncle elongate, their depths 13.8-14.5% SL, at anal fin origin and 11.4-12.2% SL, respectively; longitudinal scales 40-43; vertebrae 10 + 16 = 26; D1 VI, low in males, not extending posteriorly to origin of D2 when adpressed; fifth pelvic-fin segmented ray usually divided into 5 branches at its first (most proximal) segmenting point; naked pectoral-fin base and prepelvic area; belly with small cycloid scales except forthe narrow area around ventral midline; cheek with sensory-papillae rows arranged longitudinally, no transverse rows. Colouration: pectoral fin base with a distinct dull orange oval spot; temporal region with 2 orange stripes, reaching posteriorly to, or around, a vertical through origin of second dorsal fin; caudal fin of males with 4 vertical rows of bright orange dots, in females, a pair of vertically-arranged, rounded or rectangular black blotches at the base when alive or freshly collected (Ref. 123096).
Biology:  Occurs in the upper reaches of swift freshwater streams in montane areas of Ryukyu Is., Japan. It appears to be amphidromous, judging from small-sized eggs laid by the females at the spawning grounds in Urauchi-gawa River, Iriomote-jima I. (Ref. 123096).
IUCN Red List Status: Not Evaluated (N.E.) Ref. (130435)
Threat to humans:  harmless


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