Glyptothorax ketambe Ng & Hadiaty 2009

Ng, Heok Hee & Kottelat, Maurice, 2016, The Glyptothorax of Sundaland: a revisionary study (Teleostei: Sisoridae), Zootaxa 4188 (1), pp. 1-92 : 36-39

Glyptothorax ketambe Ng & Hadiaty 2009

( Fig. 20 )

Glyptothorax ketambe Ng & Hadiaty, 2009: 62 , Figs. 1 , 2 a, 3 (type locality: Sungai Alas at Ketambe research station, Nangroe Aceh Darussalam province, Sumatra)

Material examined. SUMATRA: MZB 8694 (holotype), 100.0 mm SL; Nangroe Aceh Darussalam: Sungai Alas at Ketambe research station . MZB 8695 (5 paratypes), 49.0–95.0 mm SL; ZRC 46421 (1 paratype), 69.1 mm SL; Nangroe Aceh Darussalam: Kutacane fish market, 3°30'N, 97°48'E.

Diagnosis. Glyptothorax ketambe can be distinguished from all other Sundaic congeners except G. famelicus and G. schmidti in having a uniformly dark body with prominent pale mid-dorsal and midlateral stripes (vs. with either uniform body with or without dark spots or a mottled body, all without prominent pale mid-dorsal and midlateral stripes). It differs from G. famelicus in having a longer head (24.0–25.5% SL vs. 22.6–23.6), a deeper caudal peduncle (7.6–8.9% SL vs. 5.8–7.3) and fewer preanal vertebrae (16–17 vs. 19–20), and from G. schmidti in having a less posteriorly-extended thoracic adhesive apparatus (not reaching vs. reaching to the level of the base of the last pectoral-fin ray) an almost straight (vs. noticeably curved) lateral margin of the thoracic adhesive apparatus (compare Figs. 3 g and 3p). The following unique combination of characters further distinguishes G. ketambe from Sundaic congeners: premaxillary toothband approximately half exposed when mouth is closed; eye diameter 8– 10% HL; interorbital distance 29–31% HL; head width 16.1–17.9% SL; anteromedial striae in thoracic adhesive apparatus absent; predorsal length 33.3–35.9% SL; prepectoral length 18.2–20.6% SL; dorsal-fin spine length 12.5–14.8% SL; smooth posterior margin of dorsal-fin spine; margin of dorsal fin concave; pectoral-fin spine length 14.3–16.6% SL; dorsal-to-adipose distance 21.5–25.6% SL; body depth at anus 12.7–15.3% SL; prepelvic length 45.4–47.8% SL; straight dorsoposterior margin of adipose fin; caudal peduncle length 20.1–22.9% SL; and post-adipose distance 19.5–21.7% SL.

Description. Morphometric data as in Table 7 . Head depressed; body 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 flat 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 small tubercles on sides of body. Lateral line complete and midlateral. Vertebrae 16+21=37 (2), 17+20=37 (3) or 17+21=38 (1).

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 directly beneath posttemporal to isthmus. First branchial arch with 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 halfway between its base and anterior orbital margin. Inner mandibular barbel origin close to midline, extending to midway between its base and that of pectoral spine. Outer mandibular barbel originating posterolateral of inner mandibular barbel, extending to base 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 in single broad semilunate band. Dentary teeth in two narrow crescentic bands separated at midline.

Thoracic adhesive apparatus present, consisting of ridges of skin in an elongate ovate field extending from isthmus to just before posterior limit of pectoral-fin base ( Fig. 3 g). Anteromedial striae absent. Narrow, v-shaped medial pit on posterior half.

Dorsal fin located above anterior third of body, with I,6 (6) rays; fin margin concave; spine short and straight, smooth on anterior and posterior margins. Adipose fin with anterior margin straight or very slightly concave and posterior margin straight. Caudal fin strongly forked, with lower lobe very slightly longer than upper lobe and i,7,8,i (6) principal rays. Procurrent rays symmetrical and extending only slightly anterior to fin base. Adipose-fin origin at vertical through base of first anal-fin ray. Anal fin with straight anterior margin and straight or slightly concave posterior margin; with iv,8 (1) or iv,9,i (5) rays. Pelvic-fin origin at vertical through posterior end of dorsal-fin base. Pelvic fin with slightly convex margin and i,5 (6) rays; tip of adpressed fin not reaching anal-fin origin. Pectoral fin with I,8,i (2) or I,9 (4) rays; posterior fin margin slightly concave; anterior spine margin smooth, posterior margin with 9–12 serrations.

Coloration. In 70% ethanol: Dorsal and lateral surfaces of head, and body dark brown, fading to beige on ventral surfaces. A faint thin, lighter brown mid-dorsal stripe extending from base of last dorsal-fin ray to origin of adipose fin; stripe very faint in some individuals. Laterosensory pores along lateral line rimmed in beige, imparting appearance of a diffuse lighter brown midlateral stripe. All fins with brown rays, and diffuse melanophores on membranes. Pectoral and pelvic fins with brown on base of fin rays and hyaline posterior margin. Anal fin with brown base and hyaline posteroventral corner. Adipose fin brown, with hyaline distal margin. Caudal fin brown, with tips of lobes hyaline. Maxillary and nasal barbels brown dorsally, beige ventrally. Mandibular barbels beige.

Distribution. Glyptothorax ketambe is known from the Alas River drainage in northern Sumatra, which drains the eastern face of the Leuser Mountain Range and the western face of the Central Gajo Mountain Range, debouching into the Indian Ocean ( Fig. 19 ).

Comparisons. Besides G. famelicus and G. schmidti (already compared with G. ketambe in the diagnosis), there are five other congeners known from Sumatra: G. amnestus , G. f u s c u s, G. keluk , G. platypogonides , and G. plectilis . Glyptothorax ketambe is further distinguished from G. amnestus in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus, having a more slender body (depth at anus 12.7–15.3% SL vs. 15.3–20.6) and a more slender caudal peduncle (depth 7.6–8.9% SL vs. 9.8–11.2), from 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 12.7–15.3% SL vs. 15.6–20.7), and from G. k el u k in having a smaller predorsal length (33.3–35.9% SL vs. 36.4–41.3), a shorter dorsal-fin spine (12.5– 14.8% SL vs. 16.0-20.1), a shorter pectoral-fin spine (14.3–16.6% SL vs. 19.4–22.9), a straight (vs. convex) dorsoposterior margin of the adipose fin, and a longer post-adipose distance (19.5–21.7% SL vs. 15.2–16.7). It further differs from G. platypogonides in having a smaller eye (diameter 8–10% HL vs. 11–14), a smaller predorsal length (33.3–35.9% SL vs. 36.5–39.1), a shorter dorsal-fin spine (12.5–14.8% SL vs. 15.6–19.3) and a shorter pectoral-fin spine (14.3–16.6% SL vs. 17.8–22.7), and from G. plectilis in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus, having a narrower head (16.1–17.9% SL vs. 18.4–23.5), a more slender body (depth at anus 12.7–15.3% SL vs. 15.3–18.8), a longer post-adipose distance (19.5–21.7% SL vs. 14.0–17.6) and a longer caudal peduncle (20.1–22.9% SL vs. 13.4–19.9).

Among the remaining Sundaic congeners, G. ketambe differs from G. decussatus in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus, having a smaller predorsal length (33.3–35.9% SL vs. 35.8– 40.4) and a longer post-adipose distance (19.5–21.7% SL vs. 16.2–17.5), from G. exodon in having the premaxillary toothband approximately half (vs. almost entirely) exposed when the mouth is closed, a smaller eye (diameter 7.5–9.6% HL vs. 10.4–13.2), a smaller prepectoral length (18.2–20.6% SL vs. 20.6–25.4), a smaller predorsal length (33.3–35.9% SL vs. 36.7–39.2), a smaller prepelvic length (45.4–47.8% SL vs. 48.6–53.0) and a shorter dorsal-fin spine (12.5–14.8% SL vs. 15.0–20.0), and from G. m a j o r in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus, having a smaller predorsal length (33.3–35.9% SL vs. 36.7–41.6), a longer post-adipose distance (19.5–21.7% SL vs. 13.6–18.6) and a longer caudal peduncle (20.1–22.9% SL vs. 14.2–19.8). It is further distinguished from G. nieuwenhuisi in having a smaller predorsal length (33.3–35.9% SL vs. 36.5–41.6), a shorter pectoral-fin spine (14.3–16.6% SL vs. 18.1–23.4), a longer dorsal-to-adipose distance (21.5–25.6% SL vs. 16.7–21.7), a longer post-adipose distance (19.5–21.7% SL vs. 16.8–19.7) and a longer caudal peduncle (20.1–22.9% SL vs. 16.8–19.5), from G. pictus in having a shorter pectoral-fin spine (14.3–16.6% SL vs. 17.3–22.9), a more slender body (depth at anus 12.7–15.3% SL vs. 15.4–20.2) and a longer dorsal-to-adipose distance (21.5–25.6% SL vs. 14.7–21.4), and from G. platypogon in having a narrower head (16.1–17.9% SL vs. 19.4–22.3), a smaller prepelvic length (45.4–47.8% SL vs. 49.1–54.6), a more slender body (depth at anus 12.7– 15.3% SL vs. 15.4–19.0), a straight (vs. convex) dorsoposterior margin of the adipose fin, a longer post-adipose distance (19.5–21.7% SL vs. 14.6–17.6) and a longer caudal peduncle (20.1–22.9% SL vs. 15.5–18.2). Glyptothorax ketambe further differs from G. prashadi in having a narrower head (16.1–17.9% SL vs. 20.2–22.8) and a concave (vs. straight) margin of the dorsal fin, from G. robustus in having (vs. lacking) a medial pit in the thoracic adhesive apparatus, a shorter pectoral-fin spine (14.3–16.6% SL vs. 16.8–19.6), a smaller predorsal length (33.3–35.9% SL vs. 36.7–40.0), a smaller prepelvic length (45.4–47.8% SL vs. 47.9–52.4), a longer dorsal-toadipose distance (21.5–25.6% SL vs. 16.9–20.4) and a longer post-adipose distance (19.5–21.7% SL vs. 17.0– 19.6), and from G. stibaros in having a narrower head (16.1–17.9% SL vs. 19.2–22.4), a smaller predorsal length (33.3–35.9% SL vs. 39.1–42.8), a smaller prepelvic length (45.4–47.8% SL vs. 48.8–55.3), a shorter dorsal-fin spine (12.5–14.8% SL vs. 15.9–20.4), a shorter pectoral-fin spine (14.3–16.6% SL vs. 18.1–22.2), a smooth (vs. serrated) posterior margin of the dorsal-fin spine, a more slender body (depth at anus 12.7–15.3% SL vs. 15.6– 20.6), a longer post-adipose distance (19.5–21.7% SL vs. 15.7–18.3) and a longer caudal peduncle (20.1–22.9% SL vs. 16.0–19.7).

Figures

FIGURE 1. Schematic illustration of thoracic adhesive apparatus of Glyptothorax, showing structures defined and mentioned in this study: anterolateral striae (ALS); anteromedial striae (AMS); medial pit (MP) (based on G. plectilis, MZB 4530, 50.2 mm SL).

FIGURE 2. Glyptothorax amnestus, MZB 17214, holotype, 88.1 mm SL; Sumatra: Padang Panjang. Dorsal, lateral and ventral views.

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 19. Map showing collection localities of Glyptothorax keluk, G. ketambe and G. major.

FIGURE 20. Glyptothorax ketambe, MZB 8694, holotype, 100.0 mm SL; Sumatra: Aceh, Sungai Alas. Dorsal, lateral and ventral views.

Tables

TABLE 7. Morphometric data for Glyptothorax ketambe (n = 6).

	Range	Mean±SD
Standard length (mm)	49.0–100.0
%SL
Predorsal length	33.3–35.9	34.2±0.90
Preanal length	64.3–67.5	66.0±1.24
Prepelvic length	45.4–47.8	46.3±0.95
Prepectoral length	18.2–20.6	19.6±0.95
Length of dorsal-fin base	11.0–13.3	11.8±0.85
Dorsal-fin spine length	12.5–14.8	13.5±0.83
Length of anal-fin base	12.2–16.8	14.9±1.81
Pelvic-fin length	16.0–16.9	16.5±0.35
Pectoral-fin length	20.3–23.0	22.2±1.01
Pectoral-fin spine length	14.3–16.6	15.3±0.96
Caudal-fin length	25.4–29.8	27.3±1.70
Length of adipose-fin base	12.0–14.5	13.5±0.89
Dorsal to adipose distance	21.5–25.6	23.3±1.38
Post-adipose distance	19.5–21.7	20.6±0.92
Length of caudal peduncle	20.1–22.9	21.1±1.02
Depth of caudal peduncle	7.6–8.9	8.2±0.47
Body depth at anus	12.7–15.3	14.4±1.04
Body depth at dorsal-fin origin	16.9–18.4	17.7±1.06
Head length	24.0–25.5	25.0±0.58
Head width	16.1–17.9	17.2±0.66
Head depth	11.8–14.7	13.0±1.07
%HL
Snout length	44–50	47±2.8
Interorbital distance	29–31	30±1.0
Eye diameter	8–10	9±0.8
Nasal barbel length	8–25	16±6.9
Maxillary barbel length	75–99	89±9.6
Inner mandibular barbel length	27–33	31±2.2
Outer mandibular barbel length	33–52	47±7.3