Glyptothorax ketambe, Ng, Heok Hee & Hadiaty, Renny K., 2009

Ng, Heok Hee & Hadiaty, Renny K., 2009, Glyptothorax ketambe, a new catfish (Teleostei: Sisoridae) from northern Sumatra, Zootaxa 2085, pp. 61-68 : 62-65

Glyptothorax ketambe sp. nov.

( Figs. 1 & 3 )

Type material. Holotype: MZB 8694, 100.0 mm SL; Sumatra: Nangroe Aceh Darussalam province, Sungai Alas at Ketambe research station; R.K. Hadiaty & A. Mun'im, 16 June 1998.

Paratypes: MZB 8695 (5), 49.0–95.0 mm SL; ZRC 46421 (1), 69.1 mm SL; Sumatra: Nangroe Aceh Darussalam province, Kutacane fish market, 3°30'N, 97°48'E; R.K. Hadiaty & A. Mun'im, 22 June 1998.

Diagnosis. Glyptothorax ketambe can be distinguished from all other Sundaic congeners except G. schmidti and G. siamensis in having a color pattern consisting of a dark brown body with yellowish midlateral and mid-dorsal stripes. It differs from G. schmidti in having a deeper caudal peduncle (7.6–8.9% SL vs. 5.8–7.3) and a less posteriorly-extended thoracic adhesive apparatus (not reaching vs. reaching to the level of the base of the last pectoral-fin ray) and from G. siamensis in having a narrower head (16.1–17.9% SL vs. 17.2–20.1) and an almost straight (vs. noticeably curved) lateral margin of the thoracic adhesive apparatus ( Fig. 2 ). There are eight other congeners from mainland Southeast Asia that share a similar color pattern of a dark-colored body (with or without distinct pale midlateral and mid-dorsal stripes) with G. ketambe : G. coracinus , G. interspinalus , G. laosensis , G. longicauda , G. longjiangensis , G. strabonis , G. trilineatus and G. zanaensis . Glyptothorax ketambe is distinguished from G. c o r a c i n u s in having a wider interorbital distance (29.0–31.2% HL vs. 26.2–26.7), from G. interspinalus in having a deeper caudal peduncle (7.6–8.9% SL vs. 6.1–8.0) and a narrower head (16.1–17.9% SL vs. 17.2–22.1), from G. l a o s e n s i s in having a narrower head (16.1–17.9% SL vs. 19.2–21.1) and a less posteriorly-extended thoracic adhesive apparatus (not reaching vs. reaching beyond the level of the base of the last pectoral-fin ray), and from G. longicauda in having a shorter caudal peduncle (20.1–22.9% SL vs. 23.6) and fewer vertebrae (37–38 vs. 42). It differs from G. longjiangensis in having tubercles on the dorsal surface of the head with a single, median ridge (vs. with anastomosing tubercles with multiple ridges) and without any pale markings on the nuchal plate (vs. part or all of the nuchal plate pale-colored), from G. strabonis in having a larger eye (7.5–9.6% HL vs. 6.2–6.5), interorbital distance (29.0–31.2% HL vs. 26.0–27.2) and fewer serrations on the posterior margin of the pectoral spine (9–12 vs. 14–16), from G. trilineatus in having a longer caudal peduncle (20.1–22.9% SL vs. 16.7–18.4), and from G. zainaensis in having a shorter adipose-fin base (12.0–14.5% SL vs. 14.4–18.4), and a less posteriorly-extended thoracic adhesive apparatus (not reaching to the level of the base of the last pectoralfin ray vs. reaching beyond).

Description. Biometric data as in Table 1 . 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 openings broad, extending from directly beneath post-temporal to isthmus. 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 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.

Holotype MZB 8694 Range Mean±SD

Standard length (mm) 100.0 49.0–100.0

%SL

Inner mandibular barbel length 30.8 27.0–32.8 31.2±2.21 Outer mandibular barbel length 50.8 32.6–52.1 47.1±7.33

Dorsal fin located above anterior third of body, with I,6 (6) rays; fin margin convex; spine short and straight, smooth on anterior and posterior margins. Adipose fin with anterior margin straight or very slightly concave and posterior margin angular. 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.

Thoracic adhesive apparatus present, consisting of ridges of skin in an elongate oval field extending from isthmus to just anterior to level of base of last pectoral-fin ray. Median depression present on posterior third of adhesive apparatus. Ridges uninterrupted and oriented anterodistally, radiating from median depression.

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 line. All fins with brown fin rays, and diffuse melanophores on fin membranes. Pectoral and pelvic fins with brown on bases 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. 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. 3 ).

Etymology. This species is named after its type locality, the Ketambe research station, which is world renowned as a site for the study of the Sumatran orangutan ( Pongo abelii ). Used as a noun in apposition.

Figures

FIGURE 1. Glyptothorax ketambe, MZB 8694, holotype, 100.0 mm SL; Sumatra: Aceh, Alas River drainage.

FIGURE 3. Collection localities of G. ketambe.

FIGURE 2. T horacic adhesive apparatus of: a. Glyptothorax ketambe, holotype, MZB 8694, 100.0 mm SL; b. G. plectilis, paratype, ZRC 46420, 44.3 mm SL; c. G. siamensis, CMK 10829, 71.8 mm SL. Illustrations not to scale.

Tables

TABLE 1. Biometric data for Glyptothorax ketambe (n = 6).

Predorsal length	34.0	33.3–35.9	34.2±0.90
Preanal length	65.0	64.3–67.5	66.0±1.24
Prepelvic length	45.7	45.4–47.8	46.3±0.95
Prepectoral length	19.1	18.2–20.6	19.6±0.95
Length of dorsal-fin base	11.4	11.0–13.3	11.8±0.85
Dorsal-spine length	12.5	12.5–14.8	13.5±0.83
Length of anal-fin base	15.5	12.2–16.8	14.9±1.81
Pelvic-fin length	16.2	16.0–16.9	16.5±0.35
Pectoral-fin length	20.3	20.3–23.0	22.2±1.01
Pectoral-spine length	14.3	14.3–16.6	15.3±0.96
Caudal-fin length	25.5	25.4–29.8	27.3±1.70
Length of adipose-fin base	13.8	12.0–14.5	13.5±0.89
Dorsal to adipose distance	23.1	21.5–25.6	23.3±1.38
Post-adipose distance	20.4	19.5–21.7	20.6±0.92
Length of caudal peduncle	21.2	20.1–22.9	21.1±1.02
Depth of caudal peduncle	8.9	7.6–8.9	8.2±0.47
Body depth at anus	15.3	12.7–15.3	14.4±1.04
Head length	24.0	24.0–25.5	25.0±0.58
Head width	17.1	16.1–17.9	17.2±0.66
Head depth	14.7	11.8–14.7	13.0±1.07
%HL
Snout length	50.4	43.6–50.4	47.0±2.75
Interorbital distance	30.4	29.0–31.2	30.1±0.99
Eye diameter	7.5	7.5–9.6	8.6±0.82
Nasal barbel length	22.5	8.0–25.2	16.4±6.87
Maxillary barbel length	95.0	74.6–98.8	87.8±9.57