Glyptothorax platypogonides (Bleeker 1855)

Ng, Heok Hee & Kottelat, Maurice, 2016, The Glyptothorax of Sundaland: a revisionary study (Teleostei: Sisoridae), Zootaxa 4188 (1), pp. 1-92 : 61-63

Glyptothorax platypogonides (Bleeker 1855)

( Fig. 31 )

Pimelodus platypogonides Bleeker, 1855a: 260 , 272 (type locality: Lahat, Sumatra).

Glyptosternon platypogonides — Bleeker, 1858c: 219; 1860a: 47.

Glyptothorax platypogonoides — Hubrecht, 1887: 11; Fowler, 1915: 220; Roberts, 1989: 136 (in part).

Glyptothorax platypogonides — Fowler, 1904: 500; Kottelat et al., 1993: 77 (not pl. 37 which is G. schmidti ); Tan & Ng, 2000: 292; Jiang et al., 2011: 280.

Glyptosternum platypogonoides —Weber & de Beaufort, 1913: 267.

Glyptothorax lampris (non Fowler, 1934)— Jiang et al., 2011: 280.

Material examined. SUMATRA: RMNH 6912 (4 syntypes), 53.6–67.1 mm SL ; RMNH 15289 (3 syntypes), 65.6– 73.5 mm SL; Sumatera Selatan: Lahat. ANSP 27285 (1), 78.0 mm SL ; Sumatera Barat: Kabupaten Tanah Datar , Batusangkar. UMMZ 243329 (1), 59.6 mm SL ; Sumatera Barat: market at Kiliranjao. UMMZ 243339 (3), 40.4– 71.7 mm SL ; ZRC 41588 (15), 43.9–78.2 mm SL, Sumatera Barat: market at Sungaidareh . ZRC 53525 (4), 38.5– 52.8 mm SL; CMK 20532 (4), 36.0– 51.1 mm SL; Sumatera Selatan: market in Lahat, Lematang (Musi) drainage, 3°48'S 103°32'E . UF 166621 (9), 40.5–56.4 mm SL; Sumatera Selatan: Air Lematang , 3°45'29.22"S 103°39'22.14"E . UF 166622 (1), 50.0 mm SL; Sumatera Selatan: Air Kikim Kecil , 3°45'49.92"S 103°27'34.08"E . UF 166626 (1), 52.4 mm SL; Lampung: Way Besai , 4°45'26.88"S 104°33'19.56"E.

MALAY PENINSULA: UMMZ 245600 (1 alc., 1 c&s), 66.2–67.8 mm SL; Thailand: Surat Thani, Tapi River drainage; Khlong Sok at Phanom. ZRC 53482 (2), 37.5–39.3 mm SL ; Malaysia: Pahang, Sungai Tembeling near Jeram Pai , Pahang River drainage, 4°05'N 102°20'E.

Diagnosis. Glyptothorax platypogonides is very similar to G. exodon in terms of overall shape (a relatively slender body and caudal peduncle) and in sharing a mottled color pattern, but can be distinguished from it in having the premaxillary toothband two-thirds (vs. almost entirely) exposed when the mouth is closed. It differs from the other Sundaic congeners in having a unique combination of the following characters: anteromedial striae in the thoracic adhesive apparatus absent; eye diameter 11–14% HL; head length 25.2–26.8% SL; head width 17.0– 20.5% SL; predorsal length 36.5–39.1% SL; pectoral-fin spine length 17.8–22.7% SL; dorsal-fin spine length 15.6–19.3% SL; smooth posterior margin of dorsal-fin spine; margin of dorsal fin concave; dorsal-to-adipose distance 20.2–23.6% SL; body depth at anus 12.1–14.8% SL; adipose-fin base length 10.7–13.7% SL; straight dorsoposterior margin of adipose fin; caudal peduncle depth 6.5–7.9% SL; post-adipose distance 17.6–21.5% SL; caudal fin without prominent dark longitudinal stripes running through each lobe; and mottled body with neither prominent pale midlateral stripe nor dark vertical bands.

Description. Morphometric data in Table 12 . Head depressed; body slender, 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 16+18=34 (1), 17+17=34 (8), 16+19=35 (1), 17+18=35 (12), 17+19=36 (4) or 18+18=36 (5).

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+5 (1), 2+6 (14) or 2+7 (5) 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 two-thirds) 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 elliptical field extending from isthmus to just beyond posterior limit of pectoral-fin base ( Fig. 3 l). Anteromedial striae absent. Narrow, v-shaped medial pit on posterior half.

Dorsal fin located above anterior third of body, with I,6 (20) 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 (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 (3), iv,8,i (5), iv,9 (5) or iv,9,i (7) 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,8 (1), I,8,i (18) or I,9 (1) rays; posterior fin margin slightly concave; anterior spine margin smooth, posterior margin with 6–14 serrations.

Coloration. In 70% ethanol: Dorsal and lateral surfaces of head, and body brown to brownish gray, fading to beige on ventral surfaces. A dark, diffuse midlateral stripe running along lateral line; lateral line without such pigmentation in some individuals, causing it to show up as paler stripe within darker stripe. Body often with four long, elliptical pale patches: first above lateral line and spanning region between dorsal and adipose fins, second below lateral line and first spot, third on anterior half of caudal peduncle above lateral line and fourth on anterior half of caudal peduncle below lateral line, with pale patches imparting appearance of dark vertical band on body between adipose and anal fins. Dorsal fin with brown base and broad subdistal triangular brown mark. Pectoral fin hyaline, with brown melanophores forming a diffuse broad, transverse band subdistally. Pelvic fin hyaline, with faint transverse brown band in middle. Anal fin with brown base and brown melanophores forming V-shaped subdistal mark on anterior half of fin; rest of fin hyaline. Adipose fin brown to brownish gray, with hyaline distal margin. Caudal fin brown to brownish gray, tips and posterior margins of lobes hyaline. Maxillary barbel brown to brownish gray dorsally, beige ventrally.

Distribution. Glyptothorax platypogonides is known from the upper part of river drainages in central and southern Sumatra (from the Batang Hari drainage southwards to the short coastal drainages that drain the southern tip of the island), as well as the Malay Peninsula in rivers on the eastern slope from the Tapi River drainage southwards to the Pahang River drainage ( Fig. 24 ).

Comparisons. There are seven other congeners known from Sumatra: G. amnestus , G. famelicus , G. f u s c u s, G. keluk , G. ketambe , G. plectilis and G. schmidti . Glyptothorax platypogonides differs from G. amnestus in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus and having a larger eye (diameter 11–14% HL vs. 6–10), a more slender body (depth at anus 12.1–14.8% SL vs. 15.3–20.6) and a more slender caudal peduncle (6.5–7.9% SL vs. 9.8–11.2), from G. famelicus in having a larger eye (diameter 11–14% HL vs. 7–8), a greater predorsal length (36.5–39.1% SL vs. 32.1–35.2) and lacking (vs. having) a prominent pale midlateral stripe on the body, and G. f u s c u s in having a concave (vs. straight) margin of the dorsal fin and a more slender body (depth at anus 12.1–14.8% SL vs. 15.6–20.7). It is distinguished from G. keluk in having a mottled (vs. uniform) coloration, a larger eye (diameter 11–14% HL vs. 7–11), a straight (vs. convex) dorsoposterior margin of the adipose fin, a shorter adipose-fin base (10.7–13.7% SL vs. 13.6–17.2) and a longer post-adipose distance (17.6–21.5% SL vs. 15.2–16.7), and from G. ketambe in having a larger eye (diameter 11–14% HL vs. 8–10), a smaller predorsal length (33.3–35.9% SL vs. 36.5–39.1), a longer dorsal-fin spine (15.6–19.3% SL vs. 12.5–14.8), a longer pectoral-fin spine (17.8–22.7% SL vs. 14.3–16.6) and lacking (vs. having) a prominent pale midlateral stripe on the body. Glyptothorax platypogonides differs from G. plectilis in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus and having a more slender body (depth at anus 12.1–14.8% SL vs. 15.3–18.8), a more slender caudal peduncle (depth 6.5–7.9% SL vs. 8.4–10.6) and a longer post-adipose distance (17.6–21.5% SL vs. 14.0– 17.6), and from G. schmidti in having a larger eye (11–14% HL vs. 5–10), a longer dorsal-fin spine (15.6–19.3% SL vs. 8.9–14.9), a shorter dorsal-to-adipose distance (20.2–23.6% SL vs. 23.9–28.1) and lacking (vs. having) a prominent pale midlateral stripe on the body.

Glyptothorax platypogonides differs from the remaining Sundaic congeners in having a more slender body (depth at anus 12.1–14.8% SL vs. 14.2–23.1); it is additionally distinguished from G. decussatus in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus, having a larger eye (diameter 11–14% HL vs. 8–9), a shorter head (25.2–26.8% SL vs. 27.2–30.2), and a deeper caudal peduncle (6.5–7.9% SL vs. 10.3–10.9), and from G. major in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus, having a larger eye (diameter 11–14% HL vs. 7–10), a shorter head (25.2–26.8% SL vs. 27.2–31.3) and a more slender caudal peduncle (depth 6.5–7.9% SL vs. 7.7–10.1). It further differs from G. p i c t u s in having a more slender caudal peduncle (depth 6.5–7.9% SL vs. 8.4–10.9) and lacking (vs. having) dark vertical bars at the adipose-fin base and the base of the caudal fin, and from G. platypogon in having a larger eye (diameter 11–14% HL vs. 7–9), a longer pectoral-fin spine (17.8–22.7% SL vs. 13.6–17.9), a shorter adipose-fin base (10.7–13.7% SL vs. 13.6–18.0), a straight (vs. convex) dorsoposterior margin of the adipose fin, a longer post-adipose distance (17.6–21.5% SL vs. 14.6–17.6) and a longer and more slender caudal peduncle (length 18.0–21.5% SL vs. 15.5–18.2; depth 6.5–7.9% SL vs. 8.0–11.4) Glyptothorax platypogonides is further distinguished from G. prashadi in having a narrower head (17.0–20.5% SL vs. 20.2–22.8), a concave (vs. straight) margin of the dorsal fin, a more slender body (depth at anus 12.1–14.8% SL vs. 15.8–18.8) and a more slender caudal peduncle (6.5–7.9% SL vs. 8.3–10.3), from G. robustus in having (vs. lacking) a medial pit in the thoracic adhesive apparatus, a longer dorsal-to-adipose distance (20.2–23.6% SL vs. 16.9–20.4) and lacking (vs. having) prominent dark longitudinal stripes running through each lobe of the caudal fin, and from G. s t i b a ro s in having a smooth (vs. serrated) posterior margin of the dorsal-fin spine and a shorter adipose-fin base (10.7–13.7% SL vs. 14.6–17.8).

Figures

FIGURE 3. Thoracic adhesive apparatus of: a. Glyptothorax amnestus, ZRC 54231, paratype, 51.2 mm SL; b. G. decussatus, MZB 17216, holotype, 74.5 mm SL; c. G. exodon, BMNH 1982.3. 29.190, paratype, 63.2 mm SL; d. G. famelicus, USNM 193015, holotype, 73.3 mm SL; e. G. f u s c u s, ZRC 42123, 54.3 mm SL; f. G. keluk, MZB 17217, holotype, 52.5 mm SL; g. G. ketambe, MZB 8694, holotype, 100.0 mm SL; h. G. major, ZRC 38761, 59.1 mm SL; i. G. nieuwenhuisi, MZB 16475, 61.0 mm SL; j. G. pictus, MZB 17218, holotype, 54.2 mm SL; k. G. platypogon, ZRC 48376, 56.3 mm SL; l. G. platypogonides, UF 166626, 52.4 mm SL; m. G. plectilis, ZRC 46420, paratype, 44.3 mm SL; n. G. prashadi, CMK 25369, 50.7 mm SL; o. G. robustus, ZRC 48377, 59.9 mm SL; p. G. schmidti, CMK 4536, 74.6 mm SL; q. G. stibaros, MZB 17215, holotype, 55.3 mm SL. Illustrations not to scale.

FIGURE 24. Map showing collection localities of Glyptothorax nieuwenhuisi, G. platypogon and G. platypogonides.

FIGURE 31. Glyptothorax platypogonides, UF 166626, 52.4 mm SL; Sumatra: Lampung: Way Besai. Dorsal, lateral and ventral views.

Tables

TABLE 12. Morphometric data for Glyptothorax platypogonides (n = 20).

	Range	Mean±SD
Standard length (mm)	48.8–80.0
%SL
Predorsal length	36.5–39.1	37.9±0.90
Preanal length	60.5–66.8	64.2±2.01
Prepelvic length	46.0–51.4	48.7±1.71
Prepectoral length	18.9–22.7	21.0±1.19
Length of dorsal-fin base	11.1–13.9	13.1±0.80
Dorsal-fin spine length	15.6–19.3	17.9±1.15
Length of anal-fin base	14.4–17.1	15.8±0.76
Pelvic-fin length	13.8–15.9	15.1±0.67
Pectoral-fin length	21.6–25.5	23.7±1.26
Pectoral-fin spine length	17.8–22.7	19.5±1.44
Caudal-fin length	25.9–31.8	29.8±1.67
Length of adipose-fin base	10.7–13.7	12.2±0.96
Dorsal to adipose distance	20.2–23.6	22.1±0.87
Post-adipose distance	17.6–21.5	19.5±1.13
Length of caudal peduncle	18.0–21.5	19.8±1.11
Depth of caudal peduncle	6.5–7.9	7.1±0.41
Body depth at anus	12.1–14.8	13.4±0.90
Body depth at dorsal-fin origin	17.3–19.6	18.5±0.86
Head length	25.2–26.8	26.0±0.49
Head width	17.0–20.5	18.3±1.09
Head depth	12.8–16.4	14.5±1.15
%HL
Snout length	44–51	48±2.2
Interorbital distance	24–29	26±1.5
Eye diameter	11–14	13±0.9
Nasal barbel length	15–23	19±2.6
Maxillary barbel length	82–106	93±8.9
Inner mandibular barbel length	33–44	37.±3.4
Outer mandibular barbel length	46–59	53±4.3