Glossogobius laticeps (De Vis, 1884)

(DZü叉Ħñṻ)

Figures 1–5

Eleotris laticeps De Vis, 1884: 692 (type: Queensland coast, Australia): Hoese & Hammer 2021: 83; Zarei et al. 2023: 38; Zarei et al. 2025: 585.

Materials Examined

NTOUP-2025-10-001, male, 1 (76.3 mm SL), Nangang River, tributary of Zhonggang River; coll. Hsien-En Li et al., 30 April 2023; NTOUP-2025-10-002, female, 1 (140.6 mm SL), Lagoon near Taijiang National Park, collected by local fisherman; unfroze and preserved by Hsien-En Li, 21 August 2019; NTOUP-2025-10-003, female, 1 (104.8 mm SL), Nangang River, tributary of Zhonggang River; coll. Hsien-En Li et al., 28 June 2023; NTOUP-2025-10-004, female, 1 (94.7 mm SL), Nangang River, tributary of Zhonggang River; coll. Hsien-En Li et al., 28 June 2023; NTOUP-2025-10-005, female, 1 (115.1 mm SL), Nangang River, tributary of Zhonggang River; coll. Hsien-En Li et al., 28 June 2023; NTOUP-2025-10-006, male, 1 (93.0 mm SL), Guandu Pier, Beitou District, Taipei City, Taiwan; coll. Hsien-En Li & Yao-Jin Wang, 9 September 2025; NTOUP-2025-10-007, male, 1 (65.4 mm SL), Nangang River, tributary of Zhonggang River; coll. Hsien-En Li et al., 28 June 2023; NTOUP-2025-10-008, male, 1 (76.6 mm SL), Nangang River, tributary of Zhonggang River; coll. Hsien-En Li et al., 28 June 2023; NTOUP-2025- 10-010, male, 1 (84.8 mm SL), Nangang River, tributary of Zhonggang River; coll. Hsien-En Li et al., 9 February 2023; NTOUP-2025-10-011, female, 1 (99.7 mm SL), Nangang River, tributary of Zhonggang River; coll. Hsien-En Li et al., 28 June 2023.

Diagnosis

D. VI-I, 9; A. I, 8; P1. 20–21; P2. I, 5 LR. 33–35; TR. 9–11; Pred. 22–24; D-P. 7–8.

Body distinctly pigmented with numerous longitudinal black streaks in juvenile and adult; tip of chin with two small patches of melanophores and mostly unpigmented medially; pectoral fin base usually with two rod-like blotches; cheeks usually with two tear-like blotches present below eye.

Redescription

Morphometric percentages shown in Table 1. Body cylindrical with a slightly spindle-shaped profile, laterally compressed at caudal peduncle; head depressed; snout prolonged with a slight bony hump at dorso-anterior tip in most males; eyes situated dorsally, lined with the dorsal margin of snout. Lower lip protruding forward beyond upper lip. Mental frenum truncate without lobes or barbels. Tongue bilobed. Gill opening large, anterior end reaching the vertical of preopercle.Anterior nostril with a short tubular opening, posterior nostril in a single pore. Male urogenital papilla elongated with a pointed tip, whereas the female papilla is short, blunt, and bears a posterior notch. Vertebrae count 10+17=27 (10), P-V=3-22110.

Fins. D1 VI; D2 I, 9; A I, 8; P1 20 (5), 21(5); P2 I, 5. D1 with the second spine longest, almost but not filiformed, rarely reaching D2 origin when depressed. D2 base greater than anal fin base; D2 origin beyond anal fin origin. P1 oblong, anterior tip reaching the vertical of anus. Pelvic fins joined with fully developed frenum and membrane, round shaped; posterior P1 tip just reaching anus. Caudal fin oblong with slightly truncate upper and lower posterior margin.

Squamation. LR. 33 (6), 34 (2), 35 (2); TR. 9 (1), 10 (7), 11 (2); Pred. 22 (8), 23 (1), 24 (1); D-P. 7 (7), 8 (3). Body with large, pointy margined ctenoid scales with fine, small ctenii. Cycloid scales covering predorsal region, pectoral base, prepelvic and thoracic region and belly. Opercle with a patch of small cycloid scales located dorsally, about 27–43 in total number (Fig. 5).

Cephalic sensory organs. See figure 3 for canal pore and papillae row arrangements. Sensory canals present; anterior oculoscapular canal with paired pores σ, α, β, ρ, ω and single pores κ and λ; posterior oculoscapular canal with paired pores Θ and τ; preopercle canal with paired pores γ, δ and ε. Infraorbital papillae rows in longitudinal pattern. Row r in a singular row, curved and continuous across snout transversely. Row s multiple, composed by 2–3 rows of papillae Condition of row a variable, in juvenile specimens (~ 50–60 mm SL) often singular or multiple with 2 rows of papillae whereas in subadults or adults (> 100 mm SL) often present as multiple row with maximum 3 rows of papillae, branched just below the midpoint of orbit in all sizes, branching row ending posteriorly with singular row of papillae. Rows c, d and e in a singular row. Rows b, cp 1 and cp 2 in a patch of multiple minute papilla, composed by 2–3, 3–4 and 2–4 rows of papillae respectively. Rows c, cp 1, cp 2, d and e with their posterior ends reaching preopercle. Row os singular with an extra singular row above in all sizes, and often with numerous short singular rows in mature individuals. Row ot multiple with 1–2 transverse rows. Row oi singular. Adult individuals often with extra singular rows present at lower margin of opercle. Row f in a huge patch of minute papillae, not expanding beyond tip of chin.

Fresh colorations. See Figures 1 and 2 for live cephalic blotching patterns and fresh postmortem coloration. Body yellowish brown in juveniles, becoming dark brown in adults, with ventral surfaces paler. Head covered with numerous reddish-purple blotches. Three reddish-purple blotches present along the dorsal margin of the eye. A distinct black streak extends from the orbit to the upper tip of the preopercle. Two broad black streaks present below the eye: the upper streak running from the anterior margin of the eye to the upper lip, and the lower streak extending from the posteroventral margin of the eye to the midpoint of the preopercle, the two forming a median angle. Lower half of cheek with two blotches, one situated at the posterior end of the maxilla. Tip of chin bearing two small patches of melanophores (Fig. 4A), becoming obscure in adults (> 90 mm SL) (Fig. 4B). A thin row of melanophores present along each side of the isthmus, also becoming obscure in adults (> 90 mm SL) (Fig. 4A). Opercle with a metallic sheen when fresh (Fig. 2).

Body with five nearly rectangular blotches arranged latero-medially; the anteriormost blotch situated just posterior to the opercle and sometimes faint, the posteriormost blotch at the caudal-fin base and occasionally forming a triangular posterior extension. These rectangular blotches bordered dorsally and ventrally by a distinct longitudinal black streak extending from the axillary region to the posterior end of the caudal peduncle, accompanied by an additional 2–3 streaks along the dorsal side of the body and weaker streaks below the lateral midline (Fig. 4B, D). Body with 4–5 saddle-like blotches. Ventral region of body entirely blotchless. D1 with a distinct or diffuse black speck near the fin base at the first spine, and with 2–3 rows of black spots. D2 with a slightly orangish-purple margin and 2–3 rows of blackish-purple spots.Anal fin transparent with a white margin. Fleshy base of P1 with two rod-like spots; fin rays yellowish overall and lacking blotches. P2 whitish. Caudal fin with an orangish dorsal margin and white ventral margin; median portion of fin with 6–9 rows of dark brown spots (Fig. 2).

Preserved coloration. Body becoming yellowish; all bright coloration fading. Melanophore blotches turn distinct, retaining the general pattern of the fresh coloration.

Distribution and habitat

For Taiwanese populations, Glossogobius laticeps is so far only known from Northerneast and southeastern Taiwan (see discussions). Juvenile prefers brackish while adults (> 90 mm SL) often inhabit freshwater habitats, and it is commonly seen to be sympatric species with other Glossogobius species such as G. aureus.

Comparisons

The Glossogobius giuris complex (sensu Hoese & Hammer 2021) is characterized by having papillae rows in multiples and having an indistinct truncate and lobe-less mental frenum. Taiwanese Glossogobius species belonging to this species complex includes the newly recorded G. laticeps and G. olivaceus, the two species can be immediately distinguished by adult blotching patterns of predorsal region (blotchless vs. possesses numerous distinct black specks), D1 (transparent with 3–4 rows of spots and a diffused blotch near fin base vs. orangish with two distinct blotches at 1 st spine and 4–5 wavy black stripes), D2 (slightly orangish-purple margin and 2–3 rows of blackish-purple spots vs. orange margin and 4 rows of stripes), anal fin (transparent with white margin vs. dusky with creamy white margin), P1 (yellowish vs. dark grey), P2 (white vs. black) and other external morphology differences.

With the often-seen sympatric G. aureus, G. laticeps can be readily identified by having lesser predorsal scales (20–21 vs. 26–27), branched infraorbital row a (vs. always unbranched) extra opercle rows (vs. always single row os without extra rows) and trunk pigmentations (rectangular spots with numerous longitudinal streaks vs. elliptical spots with cloud-like mottled blotches dorsally).