Rhinogobius phuongae, Endruweit, 2018

Endruweit, Marco, 2018, Description of four new species of freshwater gobies from the Black River drainage in China and Vietnam (Teleostei: Gobiidae), Zootaxa 4486 (3), pp. 284-310 : 302-305

Rhinogobius phuongae , new species

( Figs. 11–14 )

Holotype. ZFMK ICH-104102 , 40.0 mm SL, male; Nam Can com., Tan Uyen Cty., Lai Chau Prov., Vietnam; Nam Mu River ; coll. M. Endruweit & S.V. Ngo, 7 July 2015.

Paratypes. KIZ 2015005368-5371 , 4 specimens, 29.4–35.1 mm SL; ZFMK ICH-104101, 4103, 4104, 3, 38.2- 46.7 mm SL; data as for holotype .

Non-typic material. EPC 5397-5402, 5405-5408, 10, 30.5–45.8 mm SL; Muong So com., Phong Tho Cty., Lai Chau Prov., Vietnam; Nam So River , Nam Na River; coll. M. Endruweit & S.V. Ngo, 6 July 2015.

Diagnosis. Rhinogobius phuongae can be distinguished from its congeners by the following combination of characters: cheek with about 25 indistinct dark spots and branchiostegal membrane with white spots in males; operculum unmarked; flank plain-colored devoid of any notable marks in males, reticulate in females; unpaired fins with conspicuous very broad white distal band; pectoral fin length 20–21% SL; 8–10 [9] predorsal scales; 8–9 [9] branched rays in the second dorsal fin; and 28 vertebrae.

Description. Morphometric proportions given in Table 3. Caudal peduncle short and moderately shallow; depth 2.1–2.5 length in males, 2.0– 2.6 in females. Head short, slightly depressed, wider than deep. Eye small, dorsolateral. Interorbital distance moderate. Cheek inflated; edge of operculum represents maximum body width. Snout rounded. Mouth terminal, oblique, about 30° to body axis in males, about 40° in females. Lips thick, fleshy in males, thin in females. Maxilla extending vertical through the anterior rim of orbit. Jaws equal, each with 3–4 alternating rows of small, villiform, recurved teeth; outer row in upper jaw slightly enlarged. Mental frenum trapezoid. Gill opening relatively small, dorsally not reaching upper origin of pectoral fin, ventrally reaching forward to isthmus. Gill rakers 4 + 6. Genital papilla short, not reaching origin of anal fin. VC (10–11) + (17–18) = 28–29 [11 + 17 = 28]; AP 2; DF 3-2110, 3-22110, 3-1111, 3-22111 [3-22110]. Largest known size 46.7 mm SL (ZFMK ICH-104103, paratype, female).

Fins. D 1 IV–VII [VI]; D 2 I,8–9 [9]; A I,7–8 [8]; P 16–17 [17]; C 7 + 7. First dorsal fin spines III or IV longest, non-filamentous, reaching first branched ray of second dorsal fin when adpressed in males, not reaching origin of second dorsal fin in females. Second dorsal fin and anal fin reaching about midway to caudal-fin base in males, not reaching midway in females. Caudal fin spatulate, oblong in males, with rounded rear edge in females.

Scales. LL 28–31 [29]; TR 9–10 [10]; PD 8–10 [9]; SDP 7–8 [8]; CPS 12. Flank scales arranged in regular rows; anterior margin of predorsal squamation truncate, laterally reaching forward to about pore Θ, medianly with small cycloid scales anterior to first dorsal fin ( Fig. 13 ); anterior margin of abdominal squamation obliquely bridging space between bases of pectoral and pelvic fins. Head, nape, prepectoral, pre- and subpelvic areas naked. Scales along the abdominal midline small, cycloid.

Cephalic lateralis system. Canals: Preorbital section of anterior oculoscapular canal with terminal pore σ between nostrils, mesially; pore λ on orbital bulge; pore κ located centrally posteriorly to orbit; postorbital section of oculoscapular canal with pore ω located dorsolaterally, slightly posterior to vertical through pore α; pores α and ρ located laterally in oculoscapular groove. Posterior oculoscapular canal with terminal pores Θ and τ. Terminal pores ρ and Θ separated by distance of about 1/5 eye diameter. Preopercular canal with pores γ, δ and ε along edge of preoperculum. Sensory papillae: Row a long with about 6 papillae slanting downward anteriorly, reaching vertical through mid of orbit. Row b short, with about 10 papillae, slanting downward posteriorly. Row c long, from beneath anterior nostril to vertical through posterior rim of orbit with about 15 prominent papillae. Row d long, with about 19 papillae, running along labial groove to about posterior rim of orbit. Rows c and d nearly diverging. Row cp as single papilla located between the terminals of rows c and d. Opercular rows os, ot and oi present; ot and oi not interconnected. Approximate pathways of canals and papillae rows depicted in Figure 13 .

Coloration of preserved specimens. Body light brown, gradually darker dorsally; abdomen beige. Flank with an inconspicuous dark brown midlateral stripe in males, with black reticulate pattern in females. Scales in longitudinal series light brown with gray mark along its distal edge in males, with black pocket and mark along distal edge. Head and nape gray. Cheek light brown with about 25 indistinct gray spots in males, spots smaller than pupil, more conspicuous in females. Operculum gray, unmarked. Branchiostegal membrane gray with white spots in males, spots smaller than pupil; unmarked in females. Pectoral fin with 3–4 black spots along base; spots indistinct in males, upper spot larger and more conspicuous in females. First dorsal fin with conspicuous black blotch between spines I and III, less conspicuous in females larger than 40 mm SL. Second dorsal fin with 5–6 transverse rows of black spots. Caudal fin plain brown to black in males, with six transverse rows of black spots in females. Pectoral and pelvic fin gray. Anal fin light brown with broad black median band in males, band thinner in females. All fins except pectoral fin with conspicuous broad white distal band.

Distribution. Nam Na and Nam Mu rivers in Lai Chau Province, Vietnam ( Fig. 4 ).

Etymology. Named after Mrs Thi Dieu Phuong Nguyen of RIA1 for her enthusiastic interest in the Vietnamese fish fauna; a matronym in apposition.

Figures

FIGURE 4. Map of the Red River and adjacent drainages. Rivers: 1, Mekong; 2, Ma River, 3, Black River; 4, Red River; 5, Nanpanjiang River. Type localities: Ǫ, Rhinogobius coccinella; ●, R. nanophyllum; □, R. ngutinhoceps; ■, R. phuongae.

FIGURE 11. Rhinogobius phuongae, ZFMK ICH-104102, holotype, 40.0 mm SL, male; Tan Uyen, Lai Chau, Vietnam; Nam Mu River.

FIGURE 12. Rhinogobius phuongae, ZFMK ICH-104104, paratype, 38.2 mm SL, female; Tan Uyen, Lai Chau, Vietnam; Nam Mu River.

FIGURE 13. Rhinogobius phuongae, cephalic lateralis system, composite drawing based on holotype and paratypes.

FIGURE 14. Snout coloration, females, scale bars 2 mm; left: Rhinogobius coccinella, EPC 5334, 39.5 mm SL; right: R. honghensis, EPC 5774, 47.2 mm SL; Wenshan, Yunnan; Nanxihe River.