Navigobius, Hoese, Douglass F. & Motomura, Hiroyuki, 2009

Hoese, Douglass F. & Motomura, Hiroyuki, 2009, Descriptions of two new genera and species of ptereleotrine fishes from Australia and Japan (Teleostei: Gobioidei) with discussion of possible relationships, Zootaxa 2312, pp. 49-59 : 51-52

Navigobius gen. nov.

Type species: Navigobius dewa sp. nov.

Diagnosis. Lower lip with free ventral margin over whole length, fold narrowing at anterior tip of lower jaw; head and body compressed; body elongate; cheek, preoperculum and operculum naked; most of body scaled; most scales cycloid, but with ctenoid patch below pectoral fin and another on posterior region of caudal peduncle, imbricate, in 92–97 vertical rows; mouth terminal, only slightly protrusible, forming an angle of 27–37° to longitudinal axis of body; maxilla reaching posteriorly to below middle of eye; head pores paired laterally, with 4 pores around dorsal margin of each eye; snout relatively short, rounded, its length less than eye diameter; anterior nostril at end of short tube; posterior nostril a simple pore; head papillae in a transverse pattern; median nuchal crest, formed by very low fold of skin, from first dorsal spine onto head to just above middle to posterior end of operculum; gill opening moderate, extending from upper pectoral-fin base ventrally to just below posterior preopercular margin ( Figure 2 ); interorbital about three-quarters diameter of eye; gillrakers on first arch 5+1+10, spatulate, elongate; all rakers ossified, those on second, third and fourth arches tuberculate, with dorsal spiny projections; 2 dorsal fins, first dorsal-fin spines VI, second dorsal-fin rays I,19; anal-fin rays I,19–20; pectoral-fin rays 20; segmented caudal-fin rays usually 9+8; branched caudal-fin rays 6+5; pelvic fins separate, each with rays I,4; vertebrae 10+16; branchiostegals 5.

Etymology. from the Latin – navi – to float or swim, an allusion to the swimming habits of the species.

Relationships. Navigobius has a mixture of characters found in Ptereleotris , Nemateleotris and Parioglossus . The genus has ctenoid scales posteriorly on the body, a condition also found in Nemateleotris . Other ptereleotrine genera have only cycloid scales. The head canals are completely separate between the eyes, with paired posterior interorbital pores similar to the condition in Aioliops , Oxymetopon , Parioglossus and Pterocerdale gen nov. described below. In Nemateleotris and Ptereleotris the canals are partly fused, with a single median posterior interorbital pore. The dorsal and anal ray counts are higher than those in Aioliops , but lower than those in all other ptereleotrine genera except Parioglossus and the new genus described below. The genus differs from all genera except Aioliops , Nemateleotris and the genus described below in having weakly protrusible (versus highly protrusible) jaws. A detailed comparison of genera not treated here can be found in Rennis & Hoese (1987).

Character Nemateleotris Aioliops Oxymetopon Ptereleotris Parioglossus Navigobius Pterocerdale

Vertebrae 10+16 10+16 10+16 10+16 10+16 10+16 12+16 Longitudinal scale 110–160 0 or 37–44 85–105 100–170 0 or 61–109 97 105

count

Body scales cycloid/ cycloid cycloid/ cycloid cycloid cycloid cycloid/ctenoid

ctenoid ctenoid ctenoid (rarely 1–2

ctenii on

some scales

Figures

FIGURE 2. Head of Navigobius dewa, showing sensory papillae on side of head; arrow indicates lower attachment of gill membrane.