The Glyptothorax of Sundaland: a revisionary study (Teleostei: Sisoridae) Author Ng, Heok Hee Author Kottelat, Maurice text Zootaxa 2016 4188 1 1 92 journal article 10.11646/zootaxa.4188.1.1 03a7cb89-747a-411a-855c-f46ad7df47b8 1175-5326 165406 AA85050E-7653-44BE-9330-AC617BFE6DF8 Glyptothorax major ( Boulenger 1894 ) ( Figs. 21 , 22 ) Akysis major Boulenger 1894 : 246 ( type locality: Senah, Tagora and Baram rivers, Borneo) Glyptosternum kuekenthali Steindachner, 1901 : 448 , Pl. 18 Fig. 5 a ( type locality: Baram River, Borneo) Glyptosternum tiong Popta 1904 : 191 ( type locality: Kayan River, Borneo); 1906: 75, Fig. 16 . Glyptothorax platypogon (non Valenciennes, 1840 )— Fowler, 1905 : 470 ; Gosse, 1972 : 4 ; Chin , 1978 : 305 ; Watson & Balon, 1984 : 934 ; Chapman, 1985 : 103 ; Roberts, 1989: 135, Fig. 104 (middle); Kottelat & Lim, 1995 : 242 . Glyptosternum majus —Weber & de Beaufort, 1913 : 267 (in part). Glyptothorax major — Inger & Chin , 1962 : 145 , Fig. 73; Gosse, 1972 : 4 ; Chin , 1978 : 305 ; Watson & Balon, 1984 : 934 ; Choy & Chin , 1994 : 769 ; Choy, 1996: 380; Choy et al. , 1996: 309; Chin & Samat, 1995 : 42 ; Kottelat & Lim, 1995 : 242 ; Ng & Rachmatika, 1999 : 181 , Fig. 8 A; Kottelat & Widjanarti,2005 : 163 ; Parenti & Lim, 2005 : 191 ; Ng & Hadiaty, 2008 : 145 , Fig. 6 B; Jiang et al. , 2011 : 280 ; Grinang, 2013 : 5 . Glyptothorax cf. major — Martin-Smith 1998a : 482 ; 1998b: 368; Martin-Smith & Tan, 1998 : 591 ; Ahmad et al. , 2006 : 26 . Material examined. BORNEO: SABAH : ZRC 53518 (1), 66.4 mm SL ; ZRC 53519 (5), 55.1–78.4 mm SL; Kota Marudu , Marak Parak , Sungai Kinarom at Kampung Loguang , ca. 6 km downstream of Serinsim Station , 6°19'44"N 116°44'24"E . FMNH 99372 (1); Kota Marudu , Marak Parak , Sungai Serinsim . FMNH 99400 (1), 47.5 mm SL; Kota Marudu , Marak Parak . FMNH 44853 (1), 57.0 mm SL; Kota Belud District . FMNH 68564 (1), 114.7 mm SL; Tambunan District , Sungai Pegalan . ZRC 46770 (2), 51.7–63.8 mm SL; Keningau District , Sungai Agudon , 1.8 km from Keningau to Crocker Range National Park headquarters, Padas River drainage, 5°21'12"N 116°7'32"E . FMNH 99434 (1), 41.0 mm SL; Tenom , Malutut , Crocker Range National Park , Sungai Malutut . ZRC 40423 (1), 66.3 mm SL; Danum , stream at km 111 on main line west (logging road) after turnoff to Borneo Rainforest Lodge , 5°1'6"N 117°32'38"E . BRUNEI : ZRC 38761 (1), 60.5 mm SL; Temburong , Sungai Belalong at Kuala Belalong. SARAWAK : BMNH 1892.9 .2.59 ( 1 syntype ), 107.6 mm SL ; BMNH 1892.10.7.26 (1 syntype), 74.2 mm SL; BMNH 1893.3.6.173–178 (5 syntypes), 31.0– 84.8 mm SL, Senah, Tagora and Baram rivers. FMNH 45874 (2), 68.4–70.3 mm SL; Lawas District , Pa Brayong . ANSP 166869 (2), 85.7–95.2 mm SL; Baram River . FMNH 68563 (1), 97.0 mm SL; Miri District , Sungai Akah , Meligong Gorge . ZRC 39712 (1), 79.1 mm SL; Bintulu Division , Tatau District , Sungai Sopan . ZRC 45903 (4), 36.1–83.0 mm SL; Kapit Division , Kapit District , bamboo forest about 2 km upstream of Sungai Pelajan and about 6 km from Kapit Airport , 1°57'55"N 112°55'26"E . ZRC 45884 (5), 11.2–55.4 mm SL; Sungai Semaning , ca. 30 min by road downstream of Rejang , 1°57'31"N 112°55'31"E . FMNH 68922 (1), 96.7 mm SL; FMNH 68930 (1), 48.5 mm SL; FMNH 68940 (1), 44.0 mm SL; FMNH 68948 (1), 51.4 mm SL; Kapit District , Sungai Tekalit and Nanga Tekalit camp, Sungai Mengiong drainage . FMNH 68011 (1), 58.4 mm SL; FMNH 68012 92), 57.2–66.6 mm SL; Kapit District , Sungai Baleh , Sungai Putai camp, 1°48'N 113°45'E . FMNH 68013 (14), 33.0–67.0 mm SL; tributary of Sungai Baleh , between Sungai Entunau and Sungai Putai . ANSP 166867 (1), 54.5 mm SL; ANSP 166868 (19), 30.2–45.0 mm SL; ANSP 166869 (2), 85.7– 95.2 mm SL; Baram River . CAS-SU 32 674 (2), 52.1–59.0 mm SL; Saribas , 1°41'N 111°15'E . ZRC 43670 (1), 55.6 mm SL; Penrissen Range , Kampung Benut , Sungai Sawak , entry via road to Semongok . ZRC 45900 (1), 61.0 mm SL; Lanjak Entimau Wildlife Sanctuary , Sungai Begua , 1°39'N 112°14'E . ZRC 43609 (3), 54.1–102.9 mm SL; Bau District , Serikin area . ZRC 47550 (2), 32.3–41.9 mm SL; Kampung Bayur , foothills of Gunung Penrissen , 1°14'24"N 110°17'29"E . ZRC 39837 (1), 70.5 mm SL; Sungai Kuhas near Serian , 1°9'10"N 110°29'23"E . CMK 10841 (1), 60.5 mm SL; CMK 10835 (2), 63.4–98.2 mm SL; Sungai Engkari , Batang Ai basin. KALIMANTAN TIMUR : RMNH 7564 ( 2 syntypes of Glyptosternum tiong ), 68.3–112.7 mm SL; Kayan River . CMK 9470 (1), 70.8 mm SL; Sungai Buntul at Buntul logging camp draining into Sungai Tulit, Sebuku River drainage, 4°8'54.0"N 116°48'18.0"E . ZRC 45531 (1), 30.2 mm SL; Kayan River at the mouth of Sungai Pingai. KALIMANTAN BARAT : ZRC 38839 (6), 30.9–41.0 mm SL ; CMK 11710 (19), 26.1–43.1 mm SL; Sungai Hulu Leboyan at Keluwin , Kapuas River drainage . CAS 49418 (1), 89.7 mm SL; Sungai Tamang , small forested stream flowing into Sungai Pinoh , opposite mouth of Sungai Kelawi , Kapuas River drainage, 0°35'S 111°44'E . ZRC 53524 (4), 34.7–88.2 mm SL; Sungai Elar Hulu along buffer zone with village and Bukit Raya-Bukit Baka National Park , Katingan River drainage, 0°35'22"S 112°14'21"E . CMK 10579 (6), 20.5–66.9 mm SL; Sungai Kelawai between Nanga Pintas and about 3 km upstream, Kapuas River drainage, 0°36'49"S 111°47'22"E . CAS 49417 (2), 37.5–48.7 mm SL; Rocky channel in mainstream of Sungai Pinoh , 37 km S of Nangapinoh , Kapuas River drainage, 0°40'S 111°40'E . KALIMANTAN TENGAH : ZRC 53520 (1), 50.2 mm SL; stream at buffer zone of Bukit Raya-Bukit Baka National Park, Katingan River drainage, 0°44'55"S 112°15'51"E . ZRC 53517 (3), 71.9–112.3 mm SL; Sungai Baha’e, km 64 on logging road at buffer zone of Bukit Raya-Bukit Baka National Park, Katingan River drainage, 0°47'36"S 112°19'13"E . Diagnosis. Glyptothorax major differs from congeners in Sundaland except for G. amnestus , G. decussatus and G. plectilis in having (vs. lacking) anteromedial striae in the thoracic adhesive apparatus. It is distinguished from G. decussatus in having a more slender caudal peduncle (depth 7.7–10.1% SL vs. 10.3–10.9) and lacking (vs. having) a faint, pale band around the caudal peduncle, from G. amnestus in having the anterolateral edges of the thoracic adhesive apparatus markedly concave (vs. almost straight; compare Figs. 3 a and 3m ) and a more slender caudal peduncle (depth 7.7–10.1% SL vs. 9.8–11.2), and from G. plectilis in having the anterolateral edges of the thoracic adhesive apparatus markedly concave (vs. gently convex; compare Figs. 3 h and 3m ), a larger head (27.2–31.3% SL vs. 25.3–27.9) and non-prominent tubercles of uniform size (vs. with prominent, enlarged tubercles) along the flanks. The following unique combination of characters further distinguishes G. major from Sundaic congeners: premaxillary tooth band approximately half exposed when mouth is closed; eye diameter 7–10% HL; head width 19.6–23.8% SL; width of thoracic adhesive apparatus 1.1–1.4 times in its length vs. 1.4–1.7; predorsal length 36.7– 41.6% SL; dorsal-fin spine length 14.3–20.8% SL; body depth at anus 14.7–23.1% SL; straight dorsoposterior margin of adipose fin; post-adipose distance 13.6–18.6% SL; caudal peduncle depth 1.7–2.4 times in body depth at dorsal-fin origin; caudal peduncle length 14.2–19.8% SL; absence of both dark vertical bars at adipose-fin base and base of caudal fin and prominent pale midlateral stripe on body. Description. Morphometric data in Table 8 . Head depressed; body robust, subcylindrical. Dorsal profile rising evenly 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 even size on sides of body. Lateral line complete and midlateral. Vertebrae 17+17=34 (6), 17+18=35 (8), 18+17=35 (6), 19+16=35 (4), 17+19=36 (2) or 18+18=36 (3). TABLE 8. Morphometric data for Glyptothorax major (n=33).

Range	Mean±SD
Standard length (mm)	66.7–112.3
%SL
Predorsal length	36.7–41.6	39.1±1.05
Preanal length	64.4–71.6	67.7±1.95
Prepelvic length	48.9–55.5	51.3±1.76
Prepectoral length	19.2–27.1	22.1±2.14
Length of dorsal-fin base	12.3–16.3	14.6±1.10
Dorsal-fin spine length	14.3–20.8	17.8±1.73
Length of anal-fin base	15.4–20.4	17.0±1.23
Pelvic-fin length	12.2–17.2	15.4±1.26
Pectoral-fin length	20.4–27.7	23.9±1.68
Pectoral-fin spine length	15.3–21.5	18.2±1.63
Caudal-fin length	24.2–34.5	28.1±2.40
Length of adipose-fin base	11.6–16.8	14.5±1.21
Dorsal to adipose distance	19.0–25.5	21.9±2.07
Post-adipose distance	13.6–18.6	15.9±1.57
Length of caudal peduncle	14.2–19.8	16.8±1.35
Depth of caudal peduncle	7.7–10.1	9.1±0.58
Body depth at anus	14.7–23.1	17.3±1.81
Body depth at dorsal-fin origin	19.7–25.6	22.4±1.95
Head length	27.2–31.3	28.7±1.03
Head width	19.6–23.8	22.3±0.99
Head depth	14.7–19.4	16.5±1.09
%HL
Snout length	45–55	50±2.0
Interorbital distance	24–33	29±1.9
Eye diameter	7–10	8±1.0
Nasal barbel length	15–29	22±3.6
Maxillary barbel length	74–111	81±9.7
Inner mandibular barbel length	28–44	36±4.6
Outer mandibular barbel length	44–70	55±6.7

Head depressed and broad, triangular when viewed laterally. Snout prominent. Anterior and posterior nares large and separated only by base of nasal barbel. Gill opening broad, extending from ventral margin of posttemporal to isthmus. First branchial arch with 2+8 (3), 3+7 (1), 3+8 (23), 3+9 (2) or 3+10 (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 (approximately half) 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. FIGURE 21. Glyptothorax major , ZRC 45903, 83.0 mm SL; Borneo: Sarawak, Sungai Pelajan. Dorsal, lateral and ventral views. Thoracic adhesive apparatus consisting of keratinized striae in an elongate oblong field extending from isthmus to almost posterior limit of pectoral-fin base ( Fig. 3 h); anterolateral edges of adhesive apparatus markedly concave. Anteromedial striae present. Chevron-shaped medial pit on posterior half. Dorsal fin located above anterior third of body, with I,6 (33) rays; fin margin concave; 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 lower lobe slightly longer than upper lobe and i,7,8,i (33) 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 (2), v,7,i (1), v,8 (1), iv,8,i (4), iv,9 (8), iv,9,i (10), iv,10 (4), v,9 (2) or iv,10,i (1) rays. Pelvic-fin origin at vertical through posterior limit of dorsal-fin base. Pelvic fin with slightly convex margin and i,5 (33) rays; tip of adpressed fin not reaching anal-fin origin. Pectoral fin with I,7 (1), I,7,i (5), I,8 (24) or I,8,i (3) rays; posterior fin margin slightly concave; anterior spine margin smooth, posterior margin with 4–12 serrations. Coloration. In 70% ethanol: dorsal and lateral surfaces of head and body gray to grayish brown, fading to light gray or beige on ventral surfaces. Dorsal and lateral surfaces of head and body with small irregular darker spots; spots more prominent and denser in some individuals ( Fig. 22 ). An indistinct, light brown mid-dorsal stripe extending from base of last dorsal-fin ray to origin of adipose fin; stripe absent in some individuals. Laterosensory pores rimmed in beige, imparting appearance of a diffuse light brown or light gray midlateral line in some individuals. Dorsal and ventral surfaces of caudal peduncle slightly paler in some individuals. All fins with rays proximally gray to grayish brown, becoming hyaline more distally, and diffuse melanophores on fin membranes. Pectoral and pelvic fins with gray or grayish brown on base of rays and hyaline posterior margin. Anal fin with gray or grayish brown base; gray or grayish brown spot on anterior third of fin present in some individuals. Adipose fin gray or grayish brown with hyaline distal margin. Base of caudal fin with dark crescent in most individuals. Most of caudal-fin lobes gray or grayish brown, with hyaline tips; outermost principal caudal-fin rays with hyaline spots ( Fig. 21 ) or largely hyaline ( Fig. 22 ); median third of caudal fin lobes with hyaline spot ( Fig. 21 ) or irregular hyaline band ( Fig. 22 ). Maxillary and nasal barbels gray or grayish brown dorsally, light brown or light gray ventrally. Mandibular barbels beige or light gray. FIGURE 22. Glyptothorax major , ZRC 53518, 66.4 mm SL; Borneo: Sabah, Sungai Kinarom. Habitat. Glyptothorax major inhabits streams and rivers with swift current, typically clear water, and a rocky substrate. Distribution. Glyptothorax major is known from the middle and upper portions of river drainages that drain southern, western, northern and northeastern Borneo ( Fig. 19 ). These include (but are not limited to) the following major river drainages: Katingan, Kapuas, Rajang, Baram, Padas, and Kayan. Comparisons. Besides G. decussatus (which has already been compared with G. major in the diagnosis), there are four congeners known from Borneo: G. exodon , G. nieuwenhuisi , G. p i c t u s and G. stibaros . Glyptothorax major further differs from G. exodon in having the premaxillary tooth band approximately half (vs. almost entirely) exposed when the mouth is closed, a smaller eye (diameter 7–10% HL vs. 10–13), a wider head (19.6–23.8% SL vs. 16.0–18.1) and a shorter post-adipose distance (13.6–18.6% SL vs. 21.5–24.0), from G. nieuwenhuisi in having a relatively shorter and wider thoracic adhesive apparatus (width of thoracic adhesive apparatus 1.1–1.4 times in its length vs. 1.4–1.7), from G. pictus in lacking (vs. having) dark vertical bars at adipose-fin base and caudal-fin base, and from G. s t i b a ro s in having a smooth (vs. serrated) posterior margin of the dorsal-fin spine, a less tapering body, as manifested by the smaller ratio between the body and caudal peduncle depths (caudal peduncle depth 1.7–2.4 times in body depth at dorsal-fin origin vs. 3.4–3.8). Among the remaining Sundaic congeners, G. major further differs from G. famelicus in having a greater predorsal length (36.7–41.6% SL vs. 32.1–35.2), a longer dorsal-fin spine (14.3–20.8% SL vs. 8.9–14.0), a deeper body (depth at anus 14.7–23.1% SL vs. 11.4–14.3), a deeper caudal peduncle (7.7–10.1% SL vs. 5.8–7.3), a shorter post-adipose distance (13.6–18.6% SL vs. 19.1–22.0% SL) and lacking (vs. having) a prominent pale midlateral stripe on the body, from G. f u s c u s and G. prashadi in having a concave (vs. straight) margin of the dorsal fin, and from G. prashadi in having a shorter caudal peduncle (14.2–19.8% SL vs. 20.1–22.2). It is further distinguished from G. keluk in having a straight (vs. convex) dorsoposterior margin of the adipose fin, from G. ketambe in having a greater predorsal length (36.7–41.6% SL vs. 33.3–35.9% SL), a shorter post-adipose distance (13.6–18.6% SL vs. 19.5–21.7), a shorter caudal peduncle (14.2–19.8% SL vs. 20.1–22.9) and lacking (vs. having) a prominent pale midlateral stripe on the body, and from G. platypogon in having a straight (vs. convex) dorsoposterior margin of the adipose fin. Glyptothorax major further differs from G. platypogonides in having a smaller eye (diameter 7–10% HL vs. 11–14), a longer head (27.2–31.3% SL vs. 25.2–26.8), a deeper body (depth at anus 14.7–23.1% SL vs. 12.1–14.8) and a deeper caudal peduncle (7.7–10.1% SL vs. 6.5–7.9), from G. robustus in having (vs. lacking) a medial pit in the thoracic adhesive apparatus, a less tapering body, as manifested by the smaller ratio between the body and caudal peduncle depths (caudal peduncle depth 1.7–2.4 times in body depth at dorsal-fin origin vs. 2.2– 2.8) and lacking (vs. having) a distinct longitudinal stripe running through each lobe of the caudal fin, and from G. schmidti in having a greater predorsal length (36.7–41.6% SL vs. 31.6–36.9), a shorter and deeper caudal peduncle (caudal peduncle depth 1.6–2.2 times in its length vs. 2.2–3.0) and lacking (vs. having) a prominent pale midlateral stripe on the body. Remarks. Although we have not examined the holotype of Glyptosternum kuekenthali , we cannot find any significant differences between it and G. m a j o r from the information in the original description and the accompanying figure ( Steindachner, 1901: Pl. 18 Fig. 5 a ). We therefore consider both nominal species to be conspecific. Specimens we have identified as G. m a j o r from Sabah appear to have a more slender caudal peduncle and a denser aggregation of dark spots on the body (compare Figs. 18 and 19 ) However, as the caudal peduncle depth of the populations from Sabah (7.7–9.6% SL) shows considerable overlap with those from other parts of Borneo (8.2– 10.1% SL) and the dense aggregations of dark spots on the body are also found in some populations from western Borneo (Roberts, 1989: Fig. 104), there is no compelling reason to regard the population from Sabah as a distinct species. We have observed that in many species, the populations from Sabah show a greater inter-drainage variability, especially in the northern and northeastern drainages (e.g. Barbodes sealei , Rasbora hubbsi , Garra robertsi , Lobocheilos spp., Nemacheilus olivaceus ) and G. major fits this pattern.