Egglestonichthys melanoptera ( Visweswara Rao, 1971 )

Su, Yo, Hsu, Yu-Chieh & Ho, Hsuan-Ching, 2025, New records of two goby species from Taiwan, northwestern Pacific Ocean (Gobiiformes: Gobiidae), Zootaxa 5693 (1), pp. 66-78 : 67-72

Egglestonichthys melanoptera ( Visweswara Rao, 1971)

English name: Eggleston’s black-fin Goby

New Chinese name: AEḆ伊KṞẊ

Figs. 1–3 . Tables 1 , 2 .

Callogobius melanoptera Visweswara Rao, 1971: 44 , figs. 1a, d (Type locality: Godavari Estuary , India. Holotype: ZSI 7919/2).

Egglestonichthys melanoptera ( Visweswara Rao, 1971) : Larson & Hoese 1997: 48 (new combination and redescription). Larson & Murdy in Carpenter & Niem 2001: 3596 (listed, western Central Pacific). Larson 2013: 154 (in key). Prokofiev 2016: 808 ( Vietnam). Psomadakis et al. 2020: 548 ( Myanmar). Fujiwara et al. 2020: 96 (mentioned, compared to the new species described). Delventhal & Mooi 2023: 462 (mentioned). Ragul et al. 2024: 3 (new record from southeastern India). Chen et al. 2025:1057 (first record from Hainan Island, China)

Specimens examined

NMMB-P 22723 , 76.3 mm SL, off Dong-gang fishing port ( ca. 22°22'22"N, 120°27'34"E), Pingtung, southwestern Taiwan, 3 December 2014, bottom trawl, collected by H.-C. Ho. NMMB-P 38470 , 80.4 mm SL, off Dong-gang fishing port, 16 July 1985. NMMB-P 40719 , 69.0 mm SL, Ke-Tzu-Liao ( ca. 22°42'53"N, 120°13'12"E), Kaohsiung, southwestern Taiwan, 2 August 2021, bottom trawl, collected by S.-L. Ng. NMMB-P 41619 , 79.1 mm SL, off southwestern Taiwan, 22°38'23.78"N, 120°10'10.27"E, R/V New Ocean Researcher III ( NORIII), hr. 1400–1600, 4 November 2023, bottom trawl at speed of 2 knots for 30 minutes, depth ca. 100 m, collected by T.-J. Hu et al.

Description of Taiwanese specimens. Meristic and morphometric data are provided in Tables 1 and 2 .

Dorsal-fin rays VI–I, 10; pectoral-fin rays 20–22/20–21; pelvic-fin rays I, 5/I, 5; anal-fin rays I, 9; segmented caudal-fin rays 9/8; branched caudal-fin rays 8/7; unsegmented procurrent caudal-fin rays 6/5–6. Gill rakers on outer face of first arch 3+1+14–15=18–19. Longitudinal scale rows 33–39; transverse scale rows 10–14; circumpeduncular scales 16–18; predorsal scales 23–26 (n=2). Vertebrae 10+16=26; dorsal-fin interdigitation pattern 3/22110/9; anal-fin pterygiophores anterior to first haemal spine 2.

Body slender, greatest depth 4.1–4.8 in SL. Head oval in shape, length 3.3–3.5 in SL, its depth smaller than its length, depth 1.6–1.8 in HL; upper profile in front of dorsal fin flat; eyes moderate, 3.8–4.0 in HL; space between eyes flat and narrow, interorbital width 6.1–8.9 in HL; snout slightly rounded, its length 4.8–5.2 in HL and not protruding before premaxilla.

Mouth moderate, upper-jaw length 2.2–2.3 in HL; its posterior end slightly anterior to vertical through middle of eye. Two nostrils ( Fig. 3A, B ), with anterior nostril covered by flap and situated at horizontal through upper margin of eye; posterior nostril forming short tube, immediately in front of eye and situated at horizontal through middle of eye. Premaxilla and dentary covered with band of canine teeth, with outermost row enlarged and recurved; inner most row slightly enlarged. Vomer and palatine edentate.

Gill rakers on first arch rod-shaped and laterally compressed, with small conical teeth on inner surfaces; rakers on outer face of second to fourth arches forming bumps; rakers on inner face of outer three arches forming bumps. Pseudobranchial filaments present and short, their number undetectable. Gill membrane connected to isthmus anteriorly; ventral end of gill opening extending anteriorly to about level of posterior margin of preopercle.

Body scales deciduous, covering body, operculum, nape, interorbital region, snout, chest, and pectoral and caudal-fin bases. Nape, snout and operculum with ctenoid scales (other area undetectable). Head pores absent. Sensory papillae on head minute and shown in Fig. 3 . Transverse papillae on cheek in ca. 8 rows; those on lower jaw in ca. 9 rows.

Dorsal-fin spines flexible, with longest spine filamentous; all soft rays branched and filamentous. Pectoral fin rounded; length 2.2–2.6 in SL, its tip reaching beyond vertical through anal-fin origin. Pelvic fin long and slightly filamentous, its length 3.2–3.7 in SL; its tip reaching or slightly anterior to anus when adpressed; pelvic fin united anteriorly but without frenum. Anal-fin soft rays slightly filamentous. Caudal fin lanceolate, length 1.8–2.2 in SL. Caudal-peduncle stout, length and depth 1.2–1.3 and 2.6–2.8 in HL, respectively.

Coloration

When fresh ( Fig. 1 ), body uniformly light brown, with head darker than body; all fins dark to black; scales pockets dark brown.

When preserved ( Fig. 2 ), color similar to that of fresh. Mouth pale, with underside of tongue behind lower-jaw teeth with scarce pigments or a single black blotch.

Distribution

Originally described from India ( Visweswara Rao 1971), and later recorded from the Samor Sea, the Philippines ( Larson & Hoese 1997), Vietnam ( Larson & Hoese 1997; Prokofiev 2016), Myanmar ( Psomadakis et al. 2020), Papua New Guinea ( Larson & Hoese 1997), and Hainan Island, China ( Chen et al. 2025). Our specimens represent the northernmost record of this species, where it occurs at depths less than 100 m.

Remarks

The present specimens are identified as Egglestonichthys melanoptera ( Visweswara Rao 1971) based on the absence of a pelvic frenum, large mouth with its posterior end extending to below the eye and the dark brown to black coloration of both body and fins ( Larson & Hoese 1997; Larson 2013). Meristic data generally match earlier records ( Larson & Hoese 1997; Table 1 ). However, our specimens exhibit fewer predorsal scales (23–26 vs. 29–37 in Larson & Hoese 1997) and slightly more circumpeduncular scales (16–18 vs. 14–16). These differences may be due to the deciduous nature of the scales and their irregular arrangement, which can make scale counts variable.

Figures

FIGURE 1. Fresh (defrosted) specimen of Egglestonichthys melanoptera (Visweswara Rao, 1971), NMMB-P 41619, 79.1 mm SL, photo by T.-J. Hu.

FIGURE 2. Preserved specimens of Egglestonichthys melanoptera (Visweswara Rao, 1971). A. NMMB-P, 22723, 76.3 mm SL B. NMMB-P 41619 79.1 mm SL C. NMMB-P 38470, 80.4 mm SL D. NMMB-P 40719, 69.0 mm SL.

FIGURE 3. Line drawing of sensory papillae of Egglestonichthys melanoptera (Visweswara Rao, 1971), NMMB-P 41619, 79.1 mm SL. A. Dorsal view B. Lateral view C. Ventral view.Anterior to right. FIGURE not to scale. Damaged areas were shaded in gray. Red arrow indicates the anterior-most end of gill opening. Abbreviations: AN, anterior nostril; PN, posterior nostril.