Glossogobius laticeps ( De Vis, 1884 )

Glossogobius laticeps ( De Vis, 1884)

Figure 3 View FIGURE 3

Eleotris laticeps De Vis, 1884: 692 (Queensland coast).

Glossogobius giuris View in CoL : Akihito & Meguro 1975 (in part); Allen et al. 2002 (in part). Pusey et al. 2004: 440 (north-eastern Australia); Pusey et al. 2017: 73 (in part).

Material examined. ZM-CBSU GL1 , 10 specimens, 36.0– 73.6 mm SL, Gabrik River , Hormuzgan Province, Makran basin, Iran, 25°46’19.27”N, 58°28’1.09”E, collected by H.R. Esmaeili, S.H. Hashemi, A.H. Masoumi, S. Echreshavi, Karami and Abbasi, 29 November 2023 (COI sequence IDs: M3735B, M3792B, M3893B; GenBank accession numbers: PQ778063 – PQ778065 ) GoogleMaps .

Diagnosis. Glossogobius laticeps can be distinguished from its Indian Ocean congeners (see Introduction) by the following combination of characters: (i) head and body pigmented and eyes present; (ii) predorsal area fully scaled to behind eyes, with a distinct naked patch usually present; (iii) suborbital papillae lines 9–10, papillae Line 13 on underside of head, and papillae Line 1a on snout all doubled or tripled; (iv) papillae Line 5 below eye and suborbital papillae Line 7 doubled; and (v) blotch on caudal fin base triangular, without a distinct unpigmented gap posteriorly.

General morphology. Body proportions detailed in Table 1 View TABLE 1 : body moderately elongate, depth at pelvic-fin origin 5.6–6.12 in SL, at anal-fin origin 5.93–6.45 in SL, laterally compressed posteriorly, with shallow caudal peduncle (depth 0.34–0.42 of length). Head large, length 2.71–2.96 in SL, width 5.2–5.8 in SL, and depth at eye 7.01–7.91 in SL and 0.69–0.78 width. Postorbital profile sub-horizontal; snout long, length 1.65–1.98 of eye diameter and 2.61–2.93 in head length. Anterior nostril at end of short tube, 2–3 nostril diameters from upper lip; posterior nostril as pore without raised rim, located before eye, closer to upper lip than to eye, and about 2 posterior nostril diameters from anterior nostril. Eyes dorsolateral and large, diameter 4.83–5.42 in head length, orbit elevated. Interorbital width 1.15–1.39 in eye diameter. Mouth angled obliquely upwards; lower jaw significantly prognathous; jaw angle in front of pupil. Teeth in the upper and lower jaws conical, enlarged in the outermost and innermost rows; irregular rows of smaller teeth in between. Gill opening broad, extending just anterior to posterior margin of preoperculum.

Fins. D1 VI; D2 I/8–I/9 (I/8:1, I/9:9); A I/8–I/9 (I/8:9, I/9:1); P 18–20 (18:1, 19:3, 20:6). First dorsal fin with rounded to triangular margin; second spine longest, with spines decreasing in size to sixth spine; fin origin well behind pelvic insertion. Second dorsal fin depth equal or sub-equal to first dorsal fin; posterior rays not elongated, reaching about halfway to caudal fin when appressed; fin origin slightly in front of vertical to anal fin origin. Anal fin slightly lower than second dorsal fin; posterior rays elongated like those of second dorsal fin; last ray origin below last ray origin of second dorsal fin. Pectoral fin with rounded margin, not reaching vertical of second dorsal fin origin; all rays branched, uppermost rays not free from membrane. Pelvic disc complete, much longer than wide, ending before or reaching anus; anterior membrane present, without lateral lobes. Caudal fin with rounded margin, shorter than head length.

Squamation. Cheek naked; predorsal area fully scaled with cycloid scales but a naked patch behind postorbital pore E present. Operculum with small patch of cycloid scales; occasionally reaches mid-operculum in 1–3 vertical rows. Scale ctenii weakly developed or absent above operculum. Prepelvic area covered with cycloid scales, ending behind posterior preopercular margin; isthmus often naked. Pectoral fin base partly scaled. Abdomen covered in cycloid scales; body covered in ctenoid scales. Caudal peduncle with slightly enlarged scales. LL 30–32 (30:2, 31:4, 32:4); PD 19–25 (19:1, 21:3, 22:2, 24:3, 25:1); TR 9–11 (9:1, 10:5, 11:4).

Gill rakers (n=5). Gill rakers on outer face of first arch: 1–2+1+6–8, usually 1+1+8.

Head lateral line system. Refer to Figure 4 View FIGURE 4 for head sensory pores and papillae pattern. Head pores: anterior oculoscapular canal pores: B′, C, D, E, F, G, and H′; posterior oculoscapular canal pores: K′ and L′; preopercular canal pores: M′, N, and O′. All are paired except for C and D. Sensory papillae: Line 1a: double row starting from pore B′; Line 1b: 1 papilla above anterior nostril; Line 2: single row, continuous across snout; Line 5: below eye, doubled anteriorly, single posteriorly; Line 6: long, anteriorly joins Line 5 behind mid-eye; five suborbital longitudinal lines: 7–11. Line 7: doubled anteriorly, single row posteriorly; axis along papilla line, larger anteriorly. Line 8: larger oval papillae, axis vertical to papilla line. Lines 9 and 10: 3 rows of papillae, axis along papilla line. Line 11: single row, oval papillae, axis vertical to papilla line. Line 12: underside of head, single row, continuous. Line 13: underside of head, doubled and continuous. Line 20: transversal single row of papillae on operculum. Line 21: longitudinal and curved, single row. Line 22: short longitudinal, single row. Chin partly covered with two clusters of papillae; mental frenum free of papillae. Line 14: long single row behind eye. Line 15: single row from eye to pore K′. Line 17: single row from pore H′ to pore K′. Lines 16 and 18: short single rows, parallel, behind pore L′. Line 19: single transversal row, starting dorsally between pores G and H′, extending downward to just above pore M′.

Coloration. In life. The typical color pattern of adult specimens as described by Hoese & Hammer (2021) is not present in the collected specimens from the Gabrik River. Our specimens, which range in standard length from 36.0 to 73.6 mm, represent juvenile, young and sub-adult stages: their coloration cannot reflect the patterns exhibited by mature individuals ( Fig. 3 View FIGURE 3 ). The head and body exhibit a white and unpigmented coloration. A weakly developed dark brown bar extends from the anteroventral margin of the eye to the middle of the lips. The body lacks dorsal mottling and brown horizontal stripes above and below the midline. Along the midside, there are five weakly developed horizontally elongated spots, with the rearmost spot on the caudal fin base being the darkest and nearly square in shape. The dorsal, pectoral, pelvic, and anal fin spines, rays, and membranes are all unpigmented, while the rays of the caudal fin display minute dark spots. In preservative. The head and body are pale white, lacking pigmentation, with a distinct dark spot located at the base of the caudal fin.

Sexual dimorphism. Males have a conical urogenital papilla with a pointed posterior edge; females have a wider, trapezoid papilla with a villous posterior edge.

Distribution and habitat. Prior to this study, Glossogobius laticeps was documented solely in Papua, Indonesia, Papua New Guinea, the Northern Territory in Australia, and along the Queensland coast from Cooktown to Bundaberg, as well as in China, Vietnam, and Bangladesh ( Fig. 1 View FIGURE 1 ). Adults are typically associated with freshwater habitats, while juveniles are occasionally found in estuarine environments ( Hoese & Hammer 2021; Hammer et al. 2021). The current record from the Gabrik River in the Makran basin of southern Iran represents a significant range expansion into the Western Indian Ocean. Most streams in the Makran basin, including the Gabrik River ( Fig. 5 View FIGURE 5 ), are characterized by minimal flow, often reducing to isolated pools separated by distances of one kilometer or more, and they frequently experience desiccation along substantial portions of their length.

Discussion Phylogenetic analysis of mitochondrial COI by Hammer et al. (2021) identified four clades within Glossogobius giuris , indicating cryptic species: (i) clade A was reclassified as G. laticeps , recorded in Indonesia, Australia, China, Vietnam, Bangladesh, and now the Gabrik River, Makran Basin, southern Iran, adding to the country’s freshwater ichthyofauna; (ii) clade B, found in Australia, India, South Africa ( Fig. 6A View FIGURE 6 ), and southeastern Iran (Sarbaz River; Fig. 6B View FIGURE 6 ) ( Hammer et al. 2021; Hoese & Hammer 2021; Zarei et al. 2023b); (iii) clade C, recorded in India, Myanmar, Nepal, Bangladesh, and Vietnam ( Hammer et al. 2021; Zarei et al. 2023b); and (iv) clade D, found in southern Africa ( Fig. 6C View FIGURE 6 ) and Oman ( Fig. 6D View FIGURE 6 ), reassigned to G. tenuiformis by Al Jufaili et al. (2022). According to these studies, clades B and C remain taxonomically unresolved, despite the redescription of G. giuris based on clade B ( Hoese & Hammer 2021). However, Hamilton’s (1822) original description of G. giuris from the Ganges River lacks sufficient detail, allowing alignment with all recent redescriptions, including G. tenuiformis , G. laticeps , and G. giuris based on clade B material. There is no type material for G. giuris , and the lectotype designated by Fricke (1999) relies on Hamilton’s illustration. Clade C also lacks a morphological description ( Hammer et al. 2021). While G. tenuiformis has not been recorded in the Ganges, clades B and C are well documented. Additionally, the recent discovery of G. laticeps in southern Iran, i.e., approximately 5,500 km west of the nearest locality record in Bangladesh, suggests a broader distribution across the northern Indian Ocean, possibly including the Ganges. Therefore, a thorough phylogenetic and morphological analysis of fresh specimens from the Ganges is needed to clarify the taxonomy of the G. giuris complex.

The gobies of the Oman Sea and Persian Gulf have not been extensively studied, with data available for only a limited number of species. This is primarily due to factors such as their low economic value, small size, cryptic appearance and behavior, incomplete geographic sampling, their presence in challenging habitats that are difficult to sample, and lack of systematic studies and less attention from ichthyologists. Recent taxonomic studies in these regions however, have led to the description of several new species, including Silhouettea ghazalae ( Kovačić et al. 2020) and Oxyurichthys omanensis ( Zarei et al. 2022) , as well as new records such as Favonigobius reichei (Bleeker, 1854) by Sadeghi et al. (2017), Coryogalops tessellatus (Randall, 1994) by Sadeghi et al. (2019a), Cryptocentrus cyanotaenia (Bleeker, 1853) by Sadeghi et al. (2019b), Stonogobiops nematodes (Hoese & Randall, 1982) by Ghanbarifardi & Lagzian (2019), Palutrus scapulopunctatus (de Beaufort, 1912) and Bathygobius cocosensis (Bleeker, 1854) by Sadeghi & Esmaeili (2019a, b), Glossogobius tenuiformis (Fowler, 1934) by Al Jufaili et al. (2022), Eleotris acanthopomus (Bleeker, 1853) by Esmaeili et al. (2022), and Favonigobius gymnauchen (Bleeker, 1860) and clade B of the Glossogobius giuris by Zarei et al. (2023a, b). In the Red Sea basin, Golani & Fricke (2018) documented 153 goby species. However, a recent update by Bogorodsky & Goren (2023) added 20 species to the list and corrected the identification of seven species. These findings suggest a significant increase in goby species richness in the northwestern Indian Ocean over the past decade, largely driven by increased sampling, the integration of molecular analyses into taxonomic research, and the re-examination of previously collected specimens stored in zoological collections.

Although the biology of species within Glossogobius remains insufficiently understood, it is generally assumed that widely distributed species such as G. laticeps , G. giuris ‘ clade B ’ and G. aureus Akihito & Meguro, 1975 exhibit amphidromous behavior. These species are typically found in freshwater as adults, with juveniles occasionally inhabiting estuaries. They breed in freshwater, have marine and estuarine larval and post-larval stages, and eventually return to rivers (e.g., Hoese & Allen 2012; Hoese & Hammer 2021). Consequently, the dispersal of G. laticeps to the northwestern Indian Ocean likely occurred via larval transport facilitated by the North Equatorial Current, which flows from east to west, originating south of the Indonesian islands.