Tukugobius carpenteri ( Seale 1910 )

Endruweit, Marco, 2017, Neotype designation for Rhinogobius carpenteri Seale 1910, and its placement in Tukugobius Herre 1927 (Teleostei: Gobiidae), Zootaxa 4277 (4), pp. 549-560 : 550-555

Tukugobius carpenteri ( Seale 1910)

Figs. 1–3

Rhinogobius carpenteri Seale 1910: 535 (type locality: Philippines: Luzon: Baguio; Trinidad River); Herre 1953: 762; Kottelat 2013: 424

Tukugobius carpenteri: Herre 1927: 122 ; Koumans 1940: 184

Gobius similis: Tomiyama 1936: 68 (in part)

Rhinogobius similis: Okada 1961: 659 (in part)

Neotype. KIZ 2016003044, 47.3 mm SL, male; Philippines: Benguet Prov.: La Trinidad town; Wangan River, Balili River drainage; 16°27.965' N, 120°33.862' E, elevation 1245 m; coll. Endruweit, M., 12–13 Aug. 2016.

Additional material. KIZ 2016003032–3043, 12 specimens, 31.4–50.4 mm SL; same data as neotype.

Diagnosis. Tukugobius carpenteri can be readily distinguished from all species currently allocated in Rhinogobius by the presence of 7 pterygiophores supporting the first dorsal fin, and the first pterygiophore of the second dorsal fin inserted in interneural space 9, and from its congeners T. bucculentus and T. philippinus by the presence of a median naked strip along the full length of the belly. It is further characterized by having a relatively deep caudal peduncle with 16 circumpeduncular scales; 4–9 predorsal scales; an unscaled pectoral-fin base; modally 6 spines in the first dorsal fin; first dorsal fin not reaching origin of second dorsal fin when adpressed; a longitudinal cephalic lateralis system with a supraotic pore ω; cheek not inflated, covered with 80–100 small dark spots; the dorsal fins, and the caudal- and anal fin plain gray with a white distal band.

Description. Body anteriorly cylindrical, posteriorly compressed, proportions given in Table 1. Caudal peduncle short and deep; its depth 2.3–2.5 in its length in males, 2.0– 2.2 in females. Head moderately long, slightly depressed, wider than deep. Eye small, dorsolateral, reaching dorsal profile when viewed laterally. Interorbital distance moderate. Anterior nostril tubular, short, failing to reach labial groove; posterior nostril with a low rim. Cheek not inflated; edge of preoperculum represents maximum width. Snout rounded. Mouth terminal, oblique, about 40° to body axis. Lips thick. Maxilla reaching a vertical through the anterior rim of orbit. Upper jaw protruding; both jaws with 4–5 alternating rows of small villiform teeth; outer row notably larger, recurved. Tongue tip widely rounded to nearly truncate, free. Mental frenum not fleshy or lobed, rectangular, broadly merged, with lower lip interrupting postlabial groove. Gill opening relatively narrow, ventrally not reaching isthmus, dorsally not reaching upper origin of pectoral fin ( Fig. 2 ). Pectoral girdle beneath operculum with a hardened, smooth edge. Gill rakers 3 + 5, moderate, coniform, tips curved downward. Genital papilla moderate, reaching origin of anal fin in large specimens; pointed in males, blunt in females. VC 11 + 17–18 [17, 17n] = 28–29, epurals 1; AP 2; DF 3- 22111*0, 3- 221110 [3-22111*0, 3-22111*0n] ( Fig. 3 ).

Fins. D 1 VI–VII [VI, VI n]; D 2 I,8–9 [9, 9n]; A I,7–9 [8, 8n]; P 17–18 [18, 17n]; V I,5; C 7 + 7 branched rays. First dorsal-fin spine III or IV longest, non-filamentous, not reaching origin of second dorsal fin when adpressed. Second dorsal fin and anal fin reaching half way to caudal-fin base in males, not reaching base in females. Origin of anal fin inserted opposite of second to third branched ray of second dorsal fin. Pectoral fin oval, short, failing to reach anus. Pelvic-fin disk small, round, about as long as wide, spinous ray with a well-rounded membranous lobe; frenum high, with rounded lobes, distal margin crenate. Caudal fin spatulate with a rounded rear edge.

Scales. LL 34–38 [36, 36n]; TR 12–14 [12, 13n]; PD 4–9 [6, 6n]; SDP 11–15 [13, 13n]; CPS 16. Body with moderately large ctenoid scales; scales firmly attached; flank scales arranged in regular rows, somewhat irregular below first dorsal fin, not entirely reaching pectoral-fin axil. Anterior margin of predorsal squamation slightly bifurcate, laterally reaching forward to about pore τ, medially with small cycloid, deeply embedded scales in median line in front of first dorsal fin; abdominal squamation present between bases of pectoral and pelvic fins ( Fig. 2 ). Head, nape, prepectoral, prepelvic areas and median strip on belly naked with contiguous scales small, cycloid; a few minute cycloid scales immediately in front of anus in large females (e.g., KIZ 2016003032).

Cephalic lateralis system. Canals. Preorbital section of anterior oculoscapular canal with terminal pore σ mesially to anterior nostril; pore λ located on a vertical through the anterior rim of orbit; central pore κ located at about a vertical midline within the interorbital space; postorbital section of oculoscapular canal with supraotic pore ω located dorsolaterally, posterior to a vertical through pores α; pores α and ρ located laterally in oculoscapular groove. Posterior oculoscapular canal with two terminal pores Θ and τ. Terminal pores ρ and Θ well separated. Preopercular canal with pores γ, δ and ε along edge of preoperculum. Pores paired except κ.

D1 D2 P A

VI VII x I,8 9 x 17 18 x I,7 8 9 x 10 n 3 6.23 6 7n 8.54 6n 7 17.54 1 9n 3 8.15 LL PD TR

34 35 36 37 38 x 4 5 6 7 8 9 x 12 13 14 x 2 2 4n 3 2 36.08 1 2 4n 3 2 1 6.46 8 4n 1 12.46 SDP DF VC

11 12 13 14 15 x 22111*0 221110 x 28 29 x 1 5 3n 3 1 12.85 10n 3 6.23 9n 4 28.31 Sensory papillae. Row a with about 8 papillae, slanting downward anteriorly, past a vertical through mid of orbit. Row b with about 6 papillae, roughly S-shaped. Row c running from beneath anterior nostril to about a vertical through posterior rim of orbit, with about 18 prominent papillae, last two papillae more widely separated from others. Row d with about 28 papillae, running along labial groove to about posterior rim of orbit. Rows c and d diverging. Row cp as a single papilla located anteriorly to the terminals of rows c and d. Opercular rows os with 5 papillae, ot with 15 papillae and oi with 5 papillae; ot and oi not interconnected ( Fig. 2 ).

Coloration of preserved specimens. Notable sexual dichromatism within the examined material absent ( Fig. 1 ). Head and body beige, gradually darkening towards dorsum. Flank with coarse brown-gray mottling, notably less conspicuous below midlateral, not reaching ventral midline; 7–9 diffuse dusky brownish blotches along midlateral, sometimes coalesced; a conspicuous blackish bar at caudal-fin base connected over dorsum; a pupil-sized black spot at upper pectoral-fin base. Dorsum with 3 inconspicuous light beige saddles, one each in front of first and second dorsal fin and on caudal peduncle. Scales in longitudinal series variable, either dark brown basally to beige distally or dark gray to light gray. Predorsal area with coarse brown vermiculated pattern on a beige ground. Nape gray. Snout with a dorsal faint gray chevron-shaped mark. Cheek with 80–100 brown-gray small spots; spots about equal in size as posterior nasal opening, partially coalescent forming vermiform lines. Operculum plain gray, a few minute inconspicuous gray spots on the upper part in some specimens. Branchiostegal membrane plain gray. First dorsal fin plain dusky gray with a conspicuous broad white distal band, notably more inconspicuous posterior to spine IV. Second dorsal, caudal, and anal fin plain gray with a white distal band; a gray vertical mark along base of the caudal fin. Pectoral fin gray with brown-gray spots along its base. Pelvic fin light gray with a white distal band.

neotype, male males (n=6) females (n=7)

mean range SD mean range SD

Standard length (mm) 47.3 31.4-47.3 32.4–50.4 In percent of HL

Snout length 34.0 33.6 30.2–35.9 2.2 33.1 29.1–36.3 2.5 Eye diameter 20.4 22.0 19.9–25.6 2.4 21.9 19.5–27.0 2.7 Postorbital length 53.1 50.7 48.7–53.1 1.8 50.5 44.6–55.9 3.6 Interorbital width 9.5 8.3 6.8–10.3 1.5 8.7 6.5–11.9 1.9 Maximum head width 79.6 78.5 73.5–80.3 2.8 85.1 78.6–94.1 5.5 Head width (tip of operculum) 53.1 54.2 50.8–58.1 2.7 54.9 51.9–58.6 2.3 Pectoral-fin length 57.1 66.2 57.1–70.6 5.5 74.9 69.4–79.3 4.1 Distribution. Known from the Lagben, Amburayan, Balili and Agno rivers, northern Luzon Island, Philippines ( Fig. 4 ). It is usually the most common goby in mountainous streams above 700 m elevation. Specimens from the Chico River listed as Tukugobius carpenteri by Herre (1927) differ significantly in morphometrics, squamation and coloration and probably represent a population of T. bucculentus (listed as Tukugobius sp. G54 under comparative material).

Ecology. The neotype of Rhinogobius carpenteri and other specimens were obtained from the Wangan River, a left bank tributary of the Balili River in the vicinity of the town of La Trinidad. Coexisting fish species were Poecilia reticulata and Xiphophorus hellerii . Locals reported the Weather loach, Misgurnus anguillicaudatus , from the river. The slightly turbid, brownish, fast moving water had a temperature of 20 °C, a pH of 7.8, and a conductivity of 190 µS/cm ( Fig. 5 ). Specimen KIZ 2016003032 was dissected and contained in average 1.9 mm long and 1.2 mm wide eggs.

Figures

FIGURE 1. Tukugobius carpenteri; Benguet: La Trinidad; Balili River; upper: KIZ 2016003044, neotype of Rhinogobius carpenteri, male, 47.3 mm SL; lower: KIZ 2016003036, female, 39.6 mm.

FIGURE 2. Tukugobius carpenteri, KIZ 2016003044, neotype of Rhinogobius carpenteri, 47.3 mm SL, cephalic lateralis system; arrows indicate gill opening; dotted lines indicate extent of squamation. Scale bar 2 mm.

FIGURE 3. Tukugobius carpenteri, KIZ 2016003044, neotype of Rhinogobius carpenteri, 47.3 mm SL, radiograph; arrow indicates position of the first dorsal fin’s seventh pterygiophore.

FIGURE 4. Map of northern Luzon Island showing the collecting localities of Tukugobius carpenteri. Arrow indicates the neotype locality. 1, Lagben River; 2, Amburayan R.; 3, Balili R.; 4, Agno R.; 5, Chico R.; 6, Cagayan R.

FIGURE 5. Wangan River at La Trinidad; location where the neotype of Rhinogobius carpenteri was collected.