Glyptothorax fuscus Fowler 1934
Creators: name: Ng, Heok Hee
name: Kottelat, Maurice
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Siluriformes
Sisoridae
Glyptothorax
Glyptothorax fuscus

description: Glyptothorax fuscus Fowler 1934
(Figs. 12, 16)
Glyptothorax fuscus Fowler, 1934: 89, Figs. 31–33 (type locality: Chantaburi, Thailand); Smith, 1945: 403; Suvatti, 1981: 95; Jiang et al., 2011: 280; Rainboth et al., 2012: 70.
Glyptosternum telchitta (non Hamilton, 1822)— Duncker, 1904: 174.
Glyptothorax platypogon (non Valenciennes, 1840)—Herre & Myers, 1937: 68; Hora & Gupta, 1941: 35.
Glyptothorax telchitta (non Hamilton, 1822)— Fowler, 1938: 48.
Glyptothorax laosensis (non Fowler, 1934)— Fowler, 1939: 57.
Glyptothorax majus (non Boulenger, 1894)— Herre, 1940: 35; Tweedie, 1940: 70; Hora & Gupta, 1941: 34.
Glyptothorax callopterus Smith, 1945: 400, Fig. 87 (type locality: waterfall stream on Khao Chong, near Trang, Thailand); Suvatti, 1981: 95 (in part); Cramphorn, 1983: 20; Jiang et al., 2011: 280; Amirrudin & Zakaria-Ismail, 2014: 414.
Glyptothorax major (non Boulenger, 1894)— Smith, 1945: 401, Fig. 88; Suvatti, 1950: 303; Alfred, 1961: 6, Pl. 2 Fig. 6; 1966: 39, Pl. 6 Fig. 3; Bishop, 1973: 350; Mohsin et al., 1977: 76; Mizuno & Furtado, 1982: 323; Mohsin & Ambak, 1982: 102, Fig. 2; 1983: 123, Fig. 90; Zakaria-Ismail, 1984: 25; 1993: 208, Pl. 6a; Roberts, 1989: 134 (in part); Lim et al., 1990: 47; Zakaria-Ismail & Lim, 1995: 323, Pl. 4d; Sim, 2002: 61; Ambak et al., 2010: 86.
Glyptothorax prashadi (non Mukerji, 1932)— Smith, 1945: 402; Menon 1955: 42 (in part).
Glyptothorax aff. major —Ng & Tan, 1999: 362.
Glyptothorax cf. major — Kottelat et al., 1992: 10; Kano et al., 2013: 179.
Glyptothorax sp. cf. major —Miyazaki et al., 2013: 1041, Fig. 3 E.
Material examined. SOUTHEAST THAILAND: ANSP 59358 (holotype), 59.7 mm SL; Chantaburi. UMMZ 246371 (23), 31.9–63.1 mm SL; Chantaburi: Amphoe Soi Dau, Tambon Pathong, Klong Thepprathan. ZRC 35788–35790 (3), 21.5–33.3 mm SL; CMK 10663 (4), 23.4–38.0 mm SL; Chantaburi: about 1 km on road to Namtok Phliu after Chantaburi – Trat highway. ZRC 35757 (1), 39.7 mm SL; CMK 10721 (1), 39.7 mm SL; Trat: Klong Fit at Ban Kraduk Chang, Trat –Bo Rai road about 1–2 km after junction with road 3271.
MALAY PENINSULA: USNM 109820 (holotype of G. callopterus) 51.8 mm SL; Thailand: Trang, waterfall stream at Khao Chong. USNM 109819 (2 paratypes of G. callopterus), 48.0– 48.2 mm SL; Thailand: Trang, mountain stream at Khao Chong. UF 183902 (1), 47.3 mm SL; Thailand: Phangnga, Bangdook River, off road around PHG 3059, 8 °35'58"N 98°26'36"E. UF 183901 (4), 39.4–49.0 mm SL; Thailand: Phangnga, Bangdook River, small creek off side road around PHG 3059, 8 °34'28"N 98°26'40"E. CMK 22145 (4), 22.0– 45.8 mm SL; Thailand: Phangnga, Khlong Bok Pui, Ban Bok Pui at junction of roads 4090 and 4240, 8°34'25"N 98°34'53"E. UF 183904 (1), 50.9 mm SL; Thailand: Phangnga, Phangnga River, S of road 4090 behind small house, 8°32'20"N 98°29'14"E. UMMZ 195916 (1), 37.6 mm SL; Thailand: Phangnga, tributary of Khlong Ha Ngam, 1 km S of Ban Ang. UF 183324 (5), 33.6–59.4 mm SL; Thailand: Nakhon Si Thammarat, Ta Pae Kao river at Chang Klang, off road 4015, Tapi River drainage, 8°20'56"N 99°41'32"E. ANSP 59373 (1), 42.6 mm SL; Thailand: Nakhon Si Thammarat. ANSP 76834 (48), 33.2–58.9 mm SL; ANSP 76835 (3), 28.8–36.7 mm SL; Thailand: Trang, Waterfall at Khao Chong, 19 km E of Thap Thiang. ZRC 42162 (3), 29.2–37.5 mm SL; CMK 12117 (3), 24.9-32.2 mm SL; Thailand: Satun, stream in Ban Kong Kruat. ZRC 42098 (2), 25.9–28.5 mm SL; CMK 12045 (11), 34.1–43.4 mm SL; Thailand: Narathiwat, stream along road branching W at about 7 km on road from Waeng to Ban Bu Ke Ta. ZRC 42123 (14), 21.5–52.5 mm SL; CMK 12077 (14), 15.1–48.8 mm SL; Thailand: Narathiwat, Mae Nam Sungai Kolok at Ban Sae, 7 km S of Ban Bu Ke Ta. ZRC 41063 (24), 10.1–58.9 mm SL; Perak: Sungai Kenderong at Gerik, 5°25'29"N 101°7'39"E. ZRC 23351–23354 (4), 44.6–48.9 mm SL; ZRC 38732 (82), 18.3–56.7 mm SL; ZRC 41877 (40), 14.0–56.0 mm SL; CMK 8180 (34), 29.8–52.0 mm SL; Malaysia: Terengganu, Sungai Brang, outside Sekayu Waterfall Park. CAS-SU 31004 (1), 52.0 mm SL; Malaysia: Perak, Plus River near Pos Legap. ZRC 41042 (38), 11.9–26.0 mm SL; Malaysia: Perak, Sungai Korbu at Jalong, 4°50'58"N 101°11'8"E. ZRC 39973 (10), 15.4–35.6 mm SL; Malaysia: Perak, tributary of Sungai Korbu in the vicinity of Jalong. USNM 229305 (1), 49.6 mm SL; Malaysia: Terengganu, forest streams near Kampung Ayer Puteh (29–35 km inland from Chukai). CAS-SU 39344 (41), 27.6–53.6 mm SL; Malaysia: Perak, Tapah. CAS-SU 39343 (3), 17.9–55.4 mm SL; Malaysia: Perak, Batang Padang. ZRC 41225 (2), 25.5–27.2 mm SL; Malaysia: Pahang, Sungai Kla at Raub. CAS- SU 32677 (1), 49.0 mm SL; Malaysia: Selangor, W of Genting Sempah, 29 km E of Kuala Lumpur. CAS-SU 32678 (1), 48.2 mm SL; Malaysia: Pahang, Benus River, E of Genting Sempah. ZRC 42848 (2), 25.6–44.1 mm SL; Johor: near Mersing. ZRC 42757 (4), 27.6–52.1 mm SL; Johor: Sungai Kahang and tributary ca. 44.4 km from Mersing turnoff to Kluang just before side road to Endau Rompin Taman Negara, km 96 from Mersing to Batu Pahat, 2°3'56"N 103°31'35"E. ZRC 40257 (2), 41.6–44.5 mm SL; Malaysia: Johor, tributary of Sungai Batang Pinang, 272 km towards Kluang. CAS-SU 3 1003 (1), 41.9 mm SL; Malaysia: Johor, Muar. CAS-SU 39342 (4), 36.7–40.6 mm SL; Malaysia: Johor, Simpang Renggam. USNM 229263 (1), 49.2 mm SL; Malaysia: Johor, small forest tributaries of Sungai Sedili Besar, 10–22 km N of Kota Tingi (on road to Mersing). CAS-SU 32673 (2), 22.4–30.0 mm SL; Malaysia: Johor, Mawai district. FMNH 62019 (1), 20.2 mm SL; FMNH 62020 (1), 17.6 mm SL; Malaysia: Johor, Mawai Estate. FMNH 62317 (6), 15.3–25.3 mm SL; Malaysia: Johor, small stream along road from Kota Tinggi to Mawai. CAS-SU 132675 (3), 40.4–54.4 mm SL; Malaysia: Johor, 8 km N of Kota Tinggi. ZRC 39951 (2), 40.4–48.5 mm SL; Malaysia: Johor, Kota Tinggi area, Sungai Tementang.
SINGAPORE: CAS-SU 32674 (1), 38.9 mm SL; Mandai Road.
BANGKA: ZRC 30736–30742 (7), 34.6–45.0 mm SL; CMK 9619 (9), 28.5–45.6 mm SL; stream 9 km E of Mentok. ZRC 31263–31264 (2), 24.6–48.7 mm SL; CMK 9646 (1), 44.9 mm SL; 28 km N of Payung.
SUMATRA: UF 166633 (1), 29.3 mm SL; Sumatera Selatan: Air Rambang, 3°33'2"S 104°15'50"E. UF 166632 (1), 34.6 mm SL; Sumatera Selatan: Air Kikim Kecil, 3°45'50"S 103°27'34"E. ZRC 53528 (1), 43.3 mm SL; Sumatera Selatan: market in Lahat, Lematang (Musi) drainage, 3°48'S 103°32'E. UF 166631 (1), 46.0 mm SL; Sumatera Selatan: Air Enai, 4°3'39"S 104°2'52"E. UF 167899 (31), 23.9–58.6 mm SL; Lampung: Way Besai, 4°45'27"S 104°33'20"E. UF 166638 (1), 46.8 mm SL; Lampung: Way Sebetih, 4°37'36"S 104°59'53"E. UF 161617 (2), 51.2–60.3 mm SL; Lampung: Way Seputih draiange, 5°4'189"S 104°53'3"E.
Diagnosis. Glyptothorax fuscus differs from all Sundaic congeners except G. prashadi and G. s t i b a ro s in having a straight (vs. concave) dorsal margin of the dorsal fin. It is distinguished from G. prashadi in having an acutely (vs. broadly) rounded snout when viewed dorsally (Fig. 13), a more tapering body (caudal peduncle depth 2.3–2.8 times in body depth at dorsal origin vs. 1.8–1.9), expanded distal tips of neural spines forming (vs. not forming) a series of low bumps anterior to adipose fin and a caudal fin with acutely rounded (vs pointed) lobes and hyaline areas in the median fin rays and tips of fin lobes (vs. hyaline areas absent and caudal fin with same color pattern throughout; Fig. 14), and from G. stibaros in having a smooth (vs. serrated) posterior margin of the dorsalfin spine, smaller tubercles in the abdominal region (Fig. 15) and a less tapering body, as manifested by the smaller ratio between the body and caudal peduncle depths (caudal peduncle depth 2.3–2.8 times in body depth at dorsalfin origin vs. 3.4–3.8). The following unique combination of characters further distinguishes G. f u s c u s from Sundaic congeners: head width 18.3–23.3% SL; anteromedial striae in thoracic adhesive apparatus absent; width of thoracic adhesive apparatus 1.3–1.6 times in its length; dorsal-to-adipose distance 14.8–20.6% SL; body depth at anus 15.6–20.7% SL; straight dorsoposterior margin of adipose fin; post-adipose distance 15.7–20.8% SL; caudal peduncle depth 7.4–10.9% SL; caudal-fin length 28.7–33.9% SL; dark bands on caudal-fin lobes running divergent to longitudinal axis of lobes; lacking both prominent pale midlateral stripe on body and dark vertical bars at adipose-fin base and base of caudal fin.
Description. Morphometric data in Table 5. Head depressed; body subcylindrical. Dorsal profile rising steeply from tip of snout to origin of dorsal fin, then sloping gently ventrally from origin of dorsal fin to end of caudal peduncle. Ventral profile straight to anal-fin base, then sloping gently dorsally from anal-fin base to end of caudal peduncle. Anus and urogenital openings located at vertical through middle of adpressed pelvic fin. Skin tuberculate, with tubercles of on sides of body generally larger than those on dorsal surfaces of head and body. Lateral line complete and midlateral. Vertebrae 16+17=33 (4), 17+16=33 (2), 16+18=34 (6), 17+17=34 (17), 18+16=34 (2), 17+18=35 (8) or 18+17=35 (3).
Head depressed and broad, triangular when viewed laterally. Snout prominent. Anterior and posterior nares large and separated only by base of nasal barbel. Gill openings broad, extending from ventral margin of posttemporal to isthmus. First branchial arch with 2+6 (7), 2+7 (12) or 3+8 (1) rakers. Bony elements of dorsal surface of head covered with thick, tuberculate skin. Eye ovoid, horizontal axis longest; located entirely in dorsal half of head.
Barbels in four pairs. Maxillary barbel long and slender, extending to middle of pectoral-fin base. Nasal barbel slender, extending to midway between its base and anterior orbital margin. Inner mandibular-barbel extending to midway between its base and that of pectoral spine. Outer mandibular barbel extending to two-thirds of distance between its base and that of pectoral spine.
Mouth inferior, premaxillary tooth band partially exposed when mouth is closed. Oral teeth small and villiform, in irregular rows on all tooth-bearing surfaces. Premaxillary teeth appearing in single broad semilunate band. Dentary teeth in a single crescentic band, consisting of two separate halves tightly bound at midline.
Thoracic adhesive apparatus consisting of keratinized striae in an ovate field extending from isthmus to just beyond posterior limit of pectoral-fin base (Fig. 3 e). Narrow, chevron-shaped medial pit on posterior third. Striae around posterior half of median depression anastomosing.
Dorsal fin located above anterior third of body, with I,6 (20) rays; fin margin straight; spine short and straight, smooth on anterior and posterior margins. Adipose fin with anterior margin straight or slightly concave and posterior margin straight. Caudal fin strongly forked, with slightly rounded tips, lower lobe slightly longer than upper lobe and i,7,8,i (20) principal rays. Procurrent rays symmetrical and extending only slightly anterior to fin base. Anal-fin base vertically opposite adipose-fin base. Anal fin with straight anterior margin and straight or slightly concave posterior margin; with iv,8 (1), iv,8,i (3), iv,9 (4), v,8,i (2), iv,9,i (4), iv,10 (2), v,9 (1), iv,10,1 (1), iv, 11 (1) or v,9,i (1) rays. Pelvic-fin origin at vertical through posterior limit of dorsal-fin base. Pelvic fin with slightly convex margin and i,5 (20) rays; tip of adpressed fin not reaching anal-fin origin. Pectoral fin with I,7 (1), I,7,i (16), I,8 (1) or I,8,i (2) rays; posterior fin margin slightly concave; anterior spine margin smooth, posterior margin with 3–10 serrations.
Coloration. In 70% ethanol: dorsal and lateral surfaces of head and body reddish brown to dark gray, fading to paler color (beige to light gray) on ventral surfaces. Dorsal and lateral surfaces of head and body with small irregular darker spots in some individuals, particularly towards posterior half of fish (Fig. 16). A thin, pale (usually cream) mid-dorsal stripe extending from base of last dorsal-fin ray to origin of adipose fin; stripe indistinct or nearly absent in some individuals. Laterosensory pores rimmed in beige, imparting appearance of a diffuse light brown midlateral line in some individuals. Dorsal and ventral surfaces of caudal peduncle slightly paler in some individuals. All fins with rays proximally brown or gray, becoming hyaline more distally, and diffuse melanophores on fin membranes. Pectoral and pelvic fins with brown or gray on base of fin rays and hyaline posterior margin. Anal fin with brown base; brown spot on anterior third of fin present in some individuals. Adipose fin brown with hyaline distal margin. Base of caudal fin with dark crescent in most individuals. Each caudal-fin lobe with irregular, elongate brown or gray blotch on about half of outer fin rays; most of inner rays of lobes hyaline. Maxillary and nasal barbels brown to gray dorsally, beige ventrally. Mandibular barbels beige.
Distribution. Glyptothorax fuscus is found in forested hillstreams throughout southern Sumatra (from the Musi River drainage southwards to the short coastal drainages that drain the southern tip of the island), Bangka, the Malay Peninsula (from the southern tip of the peninsula northwards to the Tapi River drainage on the eastern side and to Phangnga on the western side), as well as the short coastal rivers draining the southeastern face of the Khao Banthat (Cardamom) Mountains in southeastern Thailand (Fig. 17). This species was also found in Singapore, but has since been extirpated there (Ng & Lim, 1997).
Habitat and biology. Glyptothorax fuscus is typically found in lower elevation hillstreams and streams draining the foothills throughout its range. Such streams typically have a moderate to swift current, a sandy bottom and thick vegetation on the banks. This species feeds on aquatic invertebrates (Kano et al., 2013).
Comparisons. Besides G. prashadi (which has already been compared with G. f u s cu s in the diagnosis), there are seven congeners known from the Malay Peninsula and Sumatra: G. amnestus, G. famelicus, G. k e l u k, G. ketambe, G. platypogonides, G. plectilis and G. s c h m i d t i. Glyptothorax fuscus further differs from G. amnestus in having a more tapering body as manifested by the larger ratio between the body and caudal peduncle depths (caudal peduncle depth 2.3–2.8 times in body depth at dorsal-fin origin vs. 1.4–2.1), from G. famelicus, G. ke t a m b e and G. schmidti in lacking (vs. with) a prominent pale midlateral stripe on the body, and in having a deeper body (depth at anus 15.6–20.7% SL vs. 11.4–15.7); it further differs from G. famelicus in having a deeper caudal peduncle (7.4–10.9% SL vs. 5.8–7.3). Glyptothorax fuscus is further distinguished from G. keluk in having a deeper body (depth at anus 15.6–20.7% SL vs. 14.0–15.8) and a straight (vs. convex) dorsoposterior margin of the adipose fin, from G. platypogonides in having a deeper body (depth at anus 15.6–20.7% SL vs. 12.1–14.8), and from G. plectilis in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus. Among congeners known only from Borneo, it further differs from G. decussatus in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus, having a more tapering body (caudal peduncle depth 2.3–2.8 times in body depth at dorsal-fin origin vs. 2.0), from G. exodon in having the premaxillary toothband not more than three-quarters (vs. almost entirely) exposed when the mouth is closed, a wider head (18.3–23.3% SL vs. 16.0–18.1), a shorter dorsal-toadipose distance (14.8–20.6% SL vs. 21.9–26.3), a shorter post-adipose distance (15.7–20.8% SL vs. 21.5–24.0) and a deeper body (depth at anus 15.6–20.7% SL vs. 13.8–15.8), and from G. major in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus. Glyptothorax fuscus is further distinguished from G. nieuwenhuisi in having a shorter, wider thoracic adhesive apparatus (width 1.3–1.6 times in its length vs. 1.6–1.9), more tapering body (caudal peduncle depth 2.3–2.8 times in body depth at dorsal-fin origin vs. 1.7–2.4), and from G. p i c t u s in lacking (vs. having) dark vertical bars at adipose-fin base and base of caudal fin. Among congeners known only from Java, G. f u s c u s further differs from G. platypogon in having a straight (vs. convex) dorsoposterior margin of the adipose fin, a longer caudal fin (28.7–33.9% SL vs. 20.1–27.0), and from G. robustus in having (vs. lacking) a medial pit in the thoracic adhesive apparatus, broader skin ridges on the thoracic adhesive apparatus (compare Figs. 3 e and 3o) and lacking (vs. having) a prominent dark longitudinal stripe running through each caudal-fin lobe.
Glyptothorax coracinus is a species that is possibly sympatric with G. f u s c u s for part of its range (southeastern Thailand). Glyptothorax fuscus differs from G. coracinus in having fewer total vertebrae (33–35 vs. 36–37) and in having a mottled brown or gray (vs. uniform blackish brown) color pattern.
Remarks. Glyptothorax fuscus is the most widely distributed Sundaic species that has often been misidentified as G. m a j o r, a species known only from Borneo. Kottelat (2001) used this name (G. f u s c u s) for a species from the Laotian Mekong, which we now reidentify as G. l a m p r i s.
description: Published as part of Ng, Heok Hee & Kottelat, Maurice, 2016, The Glyptothorax of Sundaland: a revisionary study (Teleostei: Sisoridae), pp. 1-92 in Zootaxa 4188 (1) on pages 24-32, DOI: 10.11646/zootaxa.4188.1.1, http://zenodo.org/record/165406