Glossogobius tenuiformis Fowler, 1934

Al Jufaili, Saud M., Esmaeili, Hamid Reza, Sayyadzadeh, Golnaz, Masoumi, Amir Hassan & Larson, Helen K., 2022, Redescription of the goby Glossogobius tenuiformis Fowler, 1934 (Teleostei: Gobiidae) and assignment of Oman Glossogobius populations: a morpho-molecular approach, Zootaxa 5133 (4), pp. 543-554 : 546-552

Glossogobius tenuiformis Fowler, 1934

( Figs. 2–10 )

Examined materials. Holotype: ANSP 60250, 57 mm SL; South Africa: St. Lucia Lake.—ZM-CBSU: O001. Gt 101- Gt-121, 21 specimens, 52–75 mm SL., Oman: Dhofar Governorate: Salalah, Wadi Hasik , at Hasik , 17°22’01.2”N, 55°16’58.8”E. H. R Esmaeili, S.M. Al-Jufaili, A. H Masoumi, 04, Jan. 2022.—ZM-CBSU ZM-CBSU: O002. Gt 126- Gt 143, 18, 22–39 mm SL, Oman: Sur in Al Sharqiyah South Governorate: Wadi Shab , 22°50’01”N, 59°14’20”E. H. R Esmaeili, S.M. Al-Jufaili, A. H Masoumi, 04, Jan. 2022.

Comparative materials. Glossogobius giuris, ZM-CBSU S 102-1 to S102-5, 5 specimens, 102–123 mm SL; M. Ghanbarifardi, 9 February 2022, Iran: Sarbaz River at Rask, Makran basin, 26°14’05.3”N 61°23’30.1”E .— ZM-CBSU S102-6 to S102-10 , 5, 113–180 mm SL; M. Ghanbarifardi, 11 February 2022, Iran : Sarbaz River at Pishin dam, Makran basin, 26°01’50.7”N 61°41’22.9”E.—ZM-CBSU N1060 to N1061 & N1063 to N1064, 4, 83–102 mm SL; H. Malekzehi, 10 March 2013, Iran : Sarbaz River at Siren Gur village, Makran basin.—ZM-CBSU G1 - MK, 1, 103 mm SL, A. Elmi, Iran : Sarbaz River , Makran basin . SAIAB 40657 , 6 , Tugela River mouth, Natal, South Africa ; NTM S.14696-001, 30, Mhlatuze Lagoon , Richards’s Bay Reserve, South Africa ; SAM 35053, 3 , Richards’s Bay , South Africa ; SAIAB 37615 , 2 , Zotsha River , South Africa ; SAIAB 34280 , 26 , Mhlatuze Lagoon , Richards’s Bay Sanctuary, South Africa ; SAIAB 30517 , 6 , Mfolozi , Natal, South Africa ; SAIAB 36001 , 1 , Mgeni River system, Durban, South Africa ; SAM 25299, 1 of 38 spec., Richards’s Bay , South Africa ; SAIAB 11547 , 3 , Umtata River mouth, South Africa .

Diagnosis. Glossogobius tenuiformis belongs to the G. giuris complex and is distinguished from G. giuris by each of the sensory papilla lines being composed of single rows (vs. 2–3 rows or more in several lines), the absence or very short (and often only a few papillae long) sensory papilla line 6 (vs. row 6 always distinctly present and long); lower pre-dorsal scale counts (7–16 vs. 15–24) and gill rakers on outer face of first arch 1+1+9–11 usually 1+1+10 (vs. 1–2+1+6–9, usually 1–2+1+7–8).

Glossogobius tenuiformis is also well distinguished by molecular characters among the giuris complex (Table 2). Genetically, Glossogobius tenuiformis populations from Oman show the lowest genetic distance with its other population “D” from South Africa (0.0%), and the highest genetic distance with other members of this species complex, G. laticeps from Vietnam, Bangladesh and China, G. giuris from South Africa and India and “ giuris C” from India, Myanmar, Nepal, Bangladesh and Vietnam (16%).

Description. See Figures 2–10 for general appearance, vertebrae and sensory papillae, and Table 3 for morphometric data.

Dorsal fin VI, second dorsal fin I, 9, anal fin I, 8–9, pectoral fin 17–21, segmented caudal fin 17, with 12–14 branched rays, pelvic fins I, 5. Lateral scales 28–32. Transverse backward scales 8.5–10.5. Predorsal scales 12–16.

A relatively small species, reaching to 75 mm SL. Mouth large; reaching to below a point approximately in front or equal of anterior margin of eye. Interorbital narrow, less than eye diameter. Head moderate (30–35% SL); snout broadly rounded in dorsal view; with a notch dorsally in lateral view from upper extension of ascending process of premaxilla well in front of eye. Head width larger than head depth (55–63% HL). Small bump below nostrils absent or indistinct. Tongue bilobed. Anterior nostril at end of short tube, approximately halfway between eye and upper lip. Posterior nostril well in front of eye, closer to eye than upper lip, and approximately one nostril diameters from anterior nostril. Postorbital distance moderate, larger than snout. Cheek and operculum naked. Body covered mostly with large ctenoid scales, ctenii weakly developed or absent on scales. Scales cycloid on anteromedian pre-dorsal region forward to approximately a line aligned with TLC (terminal lateral canal pore); pectoral base; pre-pelvic area and midline of belly; belly fully scaled. First dorsal fin low, with rounded to triangular margin, sometimes with second spine filamentous in males; origin of fin well behind pelvic insertion. Height of second dorsal fin subequal to first, not reaching to caudal fin. Anal fin slightly lower than second dorsal fin, not reaching to caudal fin. Pectoral fin with rounded margin, reaching to anus, insertion approximately equal to pelvic origin. Pelvic disc without thickened rays, much longer than wide. Pelvic fin reaching to or almost to anus. Caudal fin with rounded margin. Vertebrae 10+17=27 (2).

Head pores: Nasal pore immediately above posterior nostril; median anterior interorbital pore present above anterior quarter of eye; median posterior interorbital pore above posterior margin of eye; postorbital pore behind eye present in line with upper margin of pupil; infraorbital pore below postorbital present; lateral canal pore above posterior quarter of pre-operculum; terminal lateral canal pore above and just behind posterior preopercular margin; lateral canal tube detached from main lateral canal; 3 preopercular pores, upper in horizontal line with lower margin of eye; middle pore closer to lower than to upper.

Sensory Papillae ( Figure 8 ): Line 1 (before nasal pore) composed of single row of papillae. Line 2 (between nasal pores) curved, composed on single row of papillae, continuous across snout. Line 5 (suborbital) composed of one row of papillae. Line 6 (suborbital branch), short, may be reduced to 1–3 papillae or absence. Line 7–13 present and composed on single row of papillae; Line 11 shorter than other and with small papillae. Line 20 composed of one row of papillae, curved backwards ventrally, breaking up into multiple rows anteriorly to form line 23, but only along lower margin of operculum. Line 21 a curved line, composed of single row. Line 22 short. In some specimens, extensive coverage of chin by papillae, almost reaching lips, but not covering dark mental frenum. Line 15, single row of papillae from end of eye to posterior part of lateral canal tube. Line 17 single row between terminal lateral canal pore and lateral canal tube. Line 19 single behind lateral canal pore.

Coloration. Head and body brown, pale below. Top of head from interorbital region to end of snout usually darker than rest of head; a dark brown bar from anteroventral margin of eye to middle of lips; operculum usually brown, with large dark brown or a series of smaller brown blotches; mental frenum usually yellowish but pigmented in some specimens. Body with scattered brown mottling dorsally; a short, horizontally elongate, brown stripe or oblong spot above and just behind pectoral fin base. Mid-side with series of large brown spots, covering 2–3 scale rows horizontally and usually 1–2 rows vertically; base of first dorsal fin spine with prominent black spot extending onto the adjoining membrane; dorsal fins with pattern of fine brownish spots overall; caudal fin with 3–8 wavy brown to black bands; pectoral fins clear to translucent, rarely with irregular brownish-gray spots on rays, pelvic and anal fins white to gray with no defined pattern.

Distribution and Habitat. Glossogobius tenuiformis is currently known from its type locality, St. Lucia Lake, KwaZulu-Natal, localities along the South African coast from Mgeni River, Eastern Cape to KwaZulu Natal, and from Wadi Hasik and Wadi Shab, Oman ( Figure 11 ). At Wadi Hasik ( Figure 12 ), the stream is about 10 m wide, with good vegetation, a substrate consisting of coarse gravel, small boulders or silt, with very low flow and semi-transparent waters which shortly drains to the Arabian Sea. At the lower Wadi Shab, it inhabits soft bottoms with sand and silt or hard bottoms with gravel and shell sediments, without vegetation and with transparent water. The stream reaches the Oman Sea only after heavy rain.

Figures

FIGURE 2. Glossogobius tenuiformis, Holotype: ANSP 60250, 57 mm SL; South Africa: St. Lucia Lake, (photo by Kyle R. Luckenbill, Academy of Natural Sciences of Drexel University, Philadelphia).

FIGURE 3. Glossogobius tenuiformis, radiograph, Holotype: ANSP 60250, 57 mm SL; South Africa: St. Lucia Lake (photo by Kyle R. Luckenbill, Academy of Natural Sciences of Drexel University, Philadelphia).

FIGURE 4. Glossogobius tenuiformis, ZM-CBSU O001.Gt105, 53.5 mm SL; Oman: Wadi Hasik.

FIGURE 5. Glossogobius tenuiformis a, ZM-CBSU O001.Gt101, 75 mm SL; b, ZM-CBSU O001.Gt104, 59 mm SL; c, ZM- CBSU O001.Gt102, 52 mm SL; Oman: Wadi Hasik.

FIGURE 6. Glossogobius tenuiformis a, ZM-CBSU O001.Gt101, 75 mm SL; b, ZM-CBSU O001.Gt104, 59 mm SL; c, ZM- CBSU O001.Gt102, 52 mm SL; Oman: Wadi Hasik.

FIGURE 7. Glossogobius tenuiformis a, Glossogobius tenuiformis a, ZM-CBSU O001.Gt101, 75 mm SL; b, ZM-CBSU O001. Gt104, 59 mm SL; c, ZM-CBSU O001.Gt102, 52 mm SL; Oman: Wadi Hasik.

FIGURE 8. Sensory papillae in Glossogobius tenuiformis; ZM-CBSU O002.Gt144, 36 mm SL; Oman: Wadi Shab. Lines are numbered following Akihito & Meguro (1975). Pores abbreviations are PNP: posterior nasal pores, AIO: anterior interorbital pore, PIO: posterior interorbital pore, PO: postorbital pore, IFO: infraorbital pore, LC: lateral canal pore above pre-operculum, TLC: terminal lateral canal pore, LCT: lateral canal tube detached from main lateral canal.

FIGURE 9. Glossogobius tenuiformis, live specimens, Oman: Wadi Hasik.

FIGURE 10. Glossogobius tenuiformis, live specimens, Oman: Wadi Shab.

FIGURE 11. Distribution map of Glossogobius tenuiformis in Oman.

FIGURE 12. Habitat of Glossogobius tenuiformis, Oman: Wadi Hasik at Hasik, Dhofar province.