Glyptothorax nieuwenhuisi ( Vaillant 1902 )

Ng, Heok Hee & Kottelat, Maurice, 2016, The Glyptothorax of Sundaland: a revisionary study (Teleostei: Sisoridae), Zootaxa 4188 (1), pp. 1-92 : 45-48

Glyptothorax nieuwenhuisi ( Vaillant 1902)

( Fig. 23 )

Glyptosternon nieuwenhuisi Vaillant, 1902: 72 , 162, Figs. 14 , 15 (type locality: Bloeoe [=Longbluu], Borneo [about 0°42'N 114°24'E]).

Glyptosternum laak Popta, 1904: 190 (type locality: Howong River , Borneo [about 0°15'N 115°30'E]); 1905: 190; 1906: 71, Fig. 15 a–b.

Glyptosternon platypogonoides (non Bleeker, 1855) - Vaillant, 1893: 73.

Glyptosternum nieuwenhuisi — Popta, 1906: 75.

Glyptosternum majus (non Boulenger, 1894)—Weber & de Beaufort, 1913: 267 (in part).

Glyptothorax major (non Boulenger, 1894)— Christensen, 1992: 600.

Glyptothorax nieuwenhuisi — Kottelat, 1995: 414.

Material examined. BORNEO: MNHN 1891-484–487 (4 syntypes), 32.0– 52.8 mm SL; Kalimantan Barat: Sebroeang [=Seberuang]; M. Chaper, 1890–1891; RMNH 7562 (3 syntypes of G. laak ), 47.7–84.5 mm SL ; Kalimantan Timur: Howong River . MZB 16475 (2), 46.8–61.0 mm SL ; Kalimantan Timur: Sungai Senget Kiri, Mahakam River drainage. ZRC 47196 (4), 52.2–56.2 mm SL ; Kalimantan Barat: Sambas River drainage, Bengkayang near Singkawang. CMK 6697 (2), 24.9–43.1 mm SL ; Kalimantan Barat: Kapuas basin: Sungai Mandor at Mandor , 0°19'03"N 109°20'34"E. CMK 6767 (1), 38.1 mm SL ; Kalimantan Barat: 11 km SE of Sanggau on road to Sintang; small tributary of Kapuas River , 0°03'55"N 110°42'47"E. CMK 6729 (1), 45.1 mm SL ; Kalimantan Barat: Insiluk, 16 km WNW from Sanggau on road to Pontianak, 0°10'18"N 110°28'22"E. BMNH 1998.9.30.11–15 (5), 50.3 mm SL; MZB 6926 (2), 37.1–37.4 mm SL ; Kalimantan Tengah: Kecamatan Laung Tuhup, Sungai Laung at Desa Maruwei, 0°21'59"S 114°44'6"E. UMMZ 247411 (2), 38.0– 39.2 mm SL ; Kalimantan Tengah, approximately 20 km S of Muara Teweh. CMK 16692 (3), 35.5–42.1 mm SL ; Kalimantan Tengah: 15 km north of Parenggean, Sampit River basin, 1°56'S 112°43'E. USNM 393647 (3), 56.7–62.8 mm SL ; Kalimantan Selatan: Desa Tamunih, Kampung Aib, Sungai Aib , a tributary of Sungai Kusan , 3°18'0"S 115°32'37"E. CMK 8415 (1), 47.9 mm SL ; Sarawak: km 42 on road from Lundu to Kuching, west of Sungai Stinggang , 1°29'N 110°01'E.

Diagnosis. Glyptothorax nieuwenhuisi differs from Sundaic congeners in having the following unique combination of characters: premaxillary tooth band approximately one-third exposed when mouth is closed; head width 18.5–21.4% SL; width of thoracic adhesive apparatus 1.6–1.9 times in its length; anteromedial striae in thoracic adhesive apparatus absent; pectoral-fin spine length 18.1–23.4% SL; predorsal length 36.5–41.6% SL; dorsal-fin spine length 14.0–18.5% SL; smooth posterior margin of dorsal-fin spine; margin of dorsal fin concave; dorsal-to-adipose distance 16.7–21.7% SL; body depth at anus 14.5–19.4% SL; straight dorsoposterior margin of adipose fin; post-adipose distance 16.8–19.7% SL; caudal peduncle length 16.8–19.5% SL; caudal peduncle depth 7.0–8.4% SL (2.0–2.6 times in its length; 2.1–2.4 times in body depth at dorsal-fin origin); caudal fin without a prominent dark longitudinal stripe running through each lobe; and body with dark spots and lacking dark vertical bars and pale midlateral stripe.

Description. Morphometric data in Table 9 . 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 (3), 17+17=34 (3), 16+19=35 (3), or 17+18=35 (9).

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+6 (4), 2+7 (2), 3+7 (4), 4+7 (1) or 4+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 (approximately one-third) 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 narrow keratinized striae in a rhomboidal field extending from isthmus to just beyond posterior limit of pectoral-fin base ( Fig. 3 i). Anteromedial striae absent. Narrow, v-shaped medial pit on posterior half.

Dorsal fin located above anterior third of body, with I,6 (12) 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 (12) 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* (6) or iv,9 (2) rays. Pelvic-fin origin at vertical through posterior limit of dorsal-fin base. Pelvic fin with slightly convex margin and i,5 (12) rays; tip of adpressed fin not reaching anal-fin origin. Pectoral fin with I,6,i (2), I,7 (3) or I,7,i (7) rays; posterior fin margin slightly concave; anterior spine margin smooth, posterior margin with 7–10 serrations.

Coloration. In 70% ethanol: dorsal and lateral surfaces of head and body brown, fading to beige on ventral surfaces. Dorsal and lateral surfaces of head and body with small irregular darker spots in some individuals. A thin, 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, becoming hyaline more distally, 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; 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. Most of caudal-fin lobes mottled brown, with hyaline tips; outermost principal caudal-fin rays largely hayline; median third of caudal fin lobes with small hyaline patches. Maxillary and nasal barbels brown dorsally, beige ventrally. Mandibular barbels beige.

Distribution. Glyptothorax nieuwenhuisi is known from the upper portions of river drainages that drain eastern, southern and western Borneo (chiefly the Kapuas, Barito and Mahakam River drainages; Fig. 24 ).

Comparisons. There are five congeners known from Borneo: G. decussatus , G. exodon , G. major , G. p i ct u s and G. stibaros . Glyptothorax nieuwenhuisi is distinguished from G. decussatus in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus and having a more slender caudal peduncle (depth 7.0–8.4% SL vs. 10.3– 10.9), from G. exodon in having the premaxillary tooth band approximately one-third (vs. almost entirely) exposed when the mouth is closed and a wider head (18.5–21.4% SL vs. 16.0–18.1), and from G. major in having a relatively longer and narrower thoracic adhesive apparatus (width of thoracic adhesive apparatus 1.9 times in its length vs. 1.1–1.4), and without (vs. with) anteromedial striae in the thoracic adhesive apparatus. It differs from G. pictus in having a more slender caudal peduncle (depth 7.0–8.4% SL vs. 8.4–10.9) and lacking (vs. having) dark vertical bars at the adipose-fin base and the caudal-fin base, and from G. stibaros in having a smooth (vs. serrated) posterior margin of the dorsal-fin spine and a more slender body relative to the caudal peduncle (caudal peduncle depth 2.1–2.4 times in body depth at dorsal-fin origin vs. 3.4–3.8).

Among the remaining Sundaic congeners, G. nieuwenhuisi differs from G. amnestus in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus and a more slender caudal peduncle (depth 7.0–8.4% SL vs. 9.8–11.2), from G. famelicus in having a greater predorsal length (36.5–41.6% SL vs. 32.1–35.2), a longer dorsalfin spine (14.0–18.5% SL vs. 8.9–14.0), a deeper body (depth at anus 14.5–19.4% SL vs. 11.4–14.3), a shorter caudal peduncle (16.8–19.5% SL vs. 19.4–21.2) and lacking (vs. having) a prominent pale midlateral stripe on the body, and from G. f u s c u s in having a longer, narrower thoracic adhesive apparatus (width 1.6–1.9 times in its length vs. 1.3–1.7), a concave (vs. straight) margin of the dorsal fin and a more slender body relative to the caudal peduncle (caudal peduncle depth 2.1–2.4 times in body depth at dorsal-fin origin vs. 2.3–2.8). It is distinguished from G. keluk in having a straight (vs. convex) dorsoposterior margin of the adipose fin and having (vs. lacking) dark spots on the body, from G. ke t a m b e in having a greater predorsal length (36.5–41.6% SL vs. 33.3–35.9), a longer pectoral-fin spine (18.1–23.4% SL vs. 14.3–16.6), a shorter dorsal-to-adipose distance (16.7–21.7% SL vs. 21.5–25.6), a shorter post-adipose distance (16.8–19.7% SL vs. 19.5–21.7), a shorter caudal peduncle (16.8–19.5% 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 longer pectoral-fin spine (18.1–23.4% SL vs. 13.6–17.9), a straight (vs. convex) dorsoposterior margin of the adipose fin and a longer, more slender caudal peduncle (caudal peduncle depth 2.0–2.6 times in its length vs. 1.4–2.1). Glyptothorax nieuwenhuisi differs from G. platypogonides in having a deeper body (depth at anus 14.5– 19.4% SL vs. 12.1–14.8), and from G. plectilis in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus and having a more slender caudal peduncle (depth 7.0–8.4% SL vs. 8.4–10.6). It is distinguished from G. prashadi in having a concave (vs. straight) margin of the dorsal fin and a more slender caudal peduncle (7.0–8.4% SL vs. 8.3–10.3), and from G. robustus in having (vs. lacking) a medial pit in the thoracic adhesive apparatus, lacking (vs. having) a prominent dark longitudinal stripe running through each lobe of the caudal fin and a highly mottled (vs. almost uniform) body, and from G. schmidti in having a shorter dorsal-to-adipose distance (16.7– 21.7% SL vs. 23.9–28.1) and lacking (vs. having) a prominent pale midlateral stripe on the body.

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 14. Lateral views of caudal region of: a. Glyptothorax fuscus, ZRC 38732, 51.5 mm SL; b. G. prashadi, CMK 25369, 50.7 mm SL. Illustrations not to scale.

FIGURE 15. Left abdominal region showing differences in tubercle size of: a. Glyptothorax fuscus, ZRC 38732, 55.7 mm SL; b. G. stibaros, MZB 17215, holotype, 55.3 mm SL. Illustrations not to scale.

FIGURE 23. Glyptothorax nieuwenhuisi, MZB 16475, 61.0 mm SL; Borneo: Sungai Senget Kiri. Dorsal, lateral and ventral views.

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

Tables

TABLE 9. Morphometric data for Glyptothorax nieuwenhuisi (n = 7).

	Range	Mean±SD
Standard length (mm)	38.0–61.0
%SL
Predorsal length	36.5–41.6	38.4±1.59
Preanal length	63.0–71.3	66.5±2.39
Prepelvic length	48.7–55.7	51.4±2.12
Prepectoral length	20.3–27.0	22.9±1.75
Length of dorsal-fin base	13.2–16.2	14.6±0.96
Dorsal-fin spine length	14.0–18.5	16.9±1.36
Length of anal-fin base	11.9–19.0	16.8±1.77
Pelvic-fin length	13.0–16.8	15.3±1.30
Pectoral-fin length	23.1–27.9	25.1±1.45
Pectoral-fin spine length	18.1–23.4	19.8±1.68
Caudal-fin length	27.0–35.8	30.9±2.75
Length of adipose-fin base	13.2–19.6	15.6±1.83
Dorsal to adipose distance	16.7–21.7	19.0±1.40
Post-adipose distance	16.8–19.7	18.7±0.84
Length of caudal peduncle	16.8–19.5	18.8±0.74
Depth of caudal peduncle	7.0–8.4	8.0±0.46
Body depth at anus	14.5–19.4	17.4±1.57
Body depth at dorsal-fin origin	17.3–20.8	18.9±1.27
Head length	25.6–29.6	27.7±1.19
Head width	18.5–21.4	20.2±1.05
Head depth	14.1–18.7	16.7±1.43
%HL
Snout length	46–51	49±1.5
Interorbital distance	26–35	29±2.5
Eye diameter	7–12	9±1.4
Nasal barbel length	18–24	21±2.4
Maxillary barbel length	87–104	96±4.5
Inner mandibular barbel length	31–46	39±5.1
Outer mandibular barbel length	47–64	53±6.8