Glyptothorax schmidti ( Volz 1904 )

Ng, Heok Hee & Kottelat, Maurice, 2016, The Glyptothorax of Sundaland: a revisionary study (Teleostei: Sisoridae), Zootaxa 4188 (1), pp. 1-92 : 77-81

Glyptothorax schmidti ( Volz 1904)

( Fig. 38 )

Callomystax schmidti Volz, 1904: 470 (type locality: Simbolon hills, Sumatra [see Kottelat, 2013: 227])

Gagata schmidti —Weber & de Beaufort, 1913: 269.

Glyptothorax siamensis Hora, 1923: 168 , Pl. 12 Figs. 1–3 (type locality: Nakhon Si Thammarat hills, Thailand); Amirrudin & Zakaria-Ismail, 2014: 414; Shafiq et al., 2014: 826.

Glyptothorax prashadi (non Mukerji, 1932)— Smith, 1934: 299; 1945: 402; Suvatti 1950: 304; 1981: 96.

Glyptosternum platypogonoides (non Bleeker, 1855)— Tweedie, 1936: 18.

Glyptothorax platypogonoides (non Bleeker, 1855)— Herre, 1940: 36; Hora & Gupta, 1941: 35; Bishop, 1973: 350; Suvatti, 1981: 96 (in part); Zakaria-Ismail, 1984: 25; Kottelat et al., 1993: pl. 37 (not text); Zakaria-Ismail & Lim, 1995: 323, Pl. 5d.

Glyptothorax aff. platypogonoides — Zakaria-Ismail, 1993: 208, Pl. 6b.

Glyptothorax platypogonides (non Bleeker, 1855)— Hashim et al., 2012: 29.

Glyptothorax laosensis (non Fowler)—Fowler, 1939: 57; Kano et al., 2013: 179; Miyazaki et al., 2013: 1041, Fig. 3 D.

Material examined. SUMATRA: MHNG 682.22 (1 syntype), 66.2 mm SL ; Sumatera Utara: Simbolon hills [Dolok Simbolon; 3°01'N 98°54'E], 1400 masl, 4 hours from Talun Madear. USNM 193006 (2), 39.4–47.3 mm SL ; Sumatra. ZMA 119436 (1), 94.1 mm SL ; Sumatera Utara: Medan. CMK 4536 (7), 43.9–74.6 mm SL ; Sumatera Utara: Sungai Seruai at Biru Biru.

MALAY PENINSULA: ZSI F10548/1 (holotype of G. siamensis ), 110.1 mm SL; Thailand: Nakhon Si Thammarat hills. USNM 109609 (1), 61.5 mm SL ; Thailand: Nakhon Si Thammarat, Tha Di River at Ban Kiriwong. CMK 12874 (4), 55.0– 77.6 mm SL ; Thailand: Narathiwat, stream on Phu Khao Thong , 6 km W of Ban Bu Ke Ta, 5°48'31"N 101°50'57"E. ZRC 39902 (1), 37.4 mm SL ; Malaysia: Perak, tributary of Sungai Korbu in the vicinity of Jalong. ZRC 53479 (4), 40.8–111.8 mm SL ; Malaysia: Pahang, Sungai Tegi, near Kampung Kuala Tegi , Pahang River drainage, 4°26'0"N 101°33'40"E. ZRC 53480 (34), 43.9–91.2 mm SL ; Malaysia: Pahang, Sungai Kenor, a tributary of Sungai Lipis , Pahang River drainage, 3°59'0"N 101°37'33"E. CMK 10829 (5), 70.1–92.4 mm SL ; Malaysia: Pahang, Sungai Kenor, a tributary of Sungai Lipis, upstream of Kampung Buntu , Pahang River drainage, 3°58'0"N 101°37'30"E. ZRC 53481 (2), 65.3–65.6 mm SL ; Malaysia: Pahang, Sungai Rengit, camp site of Bukit Rengit Game Reserve , Pahang River drainage, 3°35'30"N 102°10'36"E. CAS-SU 32671 (1), 92.8 mm SL ; Malaysia: Selangor, hills west of Genting Sempah , 29 km E of Kuala Lumpur. CAS-SU 32672 (1), 45.3 mm SL ; Malaysia: Selangor, 24 km E of Kuala Lumpur. ZRC 2412 (2), 83.0– 89.2 mm SL ; Malaysia: Selangor, 18 km from Kuala Lumpur along Bentong Road.

MYANMAR: ZRC 22935 (1), 108.8 mm SL; Tanintharyi Region : Tanintharyi River, Tuler Kloh. CMK 24876 (3), 33.8–34.4 mm SL ; Thanintharyi Region : Tanintharyi River downstream of Myittar town ; 14°11'14"N 98°33'5"E. CMK 24900 (4), 39.1–51.5 mm SL ; Thanintharyi Region: Chaung Gyi (stream) tributary Khamaungthawe near upper Seikphyone village; 14°20'6"N 98°26'7"E. CMK 24976, (6), 40.9–84.7 mm SL ; Thanintharyi Region: Kamate Chaung, east of Myaekanbaw ; 14°20'7"N 98°31'4"E. CMK 24999 (21), 42.3–84.1 mm SL ; Thanintharyi Region: Kamate Chaung, east of Myaekanbaw ; 14°20'52"N 98°31'28"E.

Diagnosis. Glyptothorax schmidti can be distinguished from all other Sundaic congeners except G. famelicus and G. ketambe 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, in both cases without prominent pale mid-dorsal and midlateral stripes). It differs from G. famelicus in having in a shorter thoracic adhesive apparatus (not reaching vs. reaching to or just beyond the level of the last pectoral-fin-ray bases; 55–60% HL vs. 63–71) and from G. ketambe in having a longer head (24.0–25.5% SL vs. 22.6–23.6) and a deeper caudal peduncle (7.6–8.9% SL vs. 5.8–7.3). The following unique combination of characters further distinguishes G. schmidti from its Sundaic congeners: premaxillary tooth band approximately half exposed when mouth is closed; eye diameter 5–10% HL; interorbital distance 27–33% HL; anteromedial striae in the thoracic adhesive apparatus absent; pectoral-fin spine length 14.0–18.3% SL; predorsal length 31.6–36.9% SL; dorsal-fin spine length 8.9–14.9% SL; smooth posterior margin of dorsal-fin spine; margin of dorsal fin concave; dorsal-to-adipose distance 23.9–28.1% SL; adipose-fin base length 10.1–14.9% SL; straight dorsoposterior margin of adipose fin; body depth at anus 11.4–15.7% SL; caudal peduncle depth 2.2–3.0 times in its length; caudal peduncle length 18.7–21.4% SL; and post-adipose distance 18.9–22.0% SL.

Description. Morphometric data in Table 16 . 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 17+19=36 (1), 18+19=37 (15), 19+18=37 (9), 20+17=37 (1), 18+20=38 (3) or 19+19=38 (13).

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+7 (5), 2+8 (20), 2+9 (1) or 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 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.

Thoracic adhesive apparatus consisting of keratinized striae in an ovate field extending from isthmus to posterior limit of pectoral-fin base ( Fig. 3 p). Anteromedial striae absent. Narrow, v-shaped medial pit on posterior third to posterior half.

Dorsal fin located above anterior third of body, with I,6 (27) 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 i,7,8,i (27) 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 iii,10 (1), iv,9 (5), iv,9,i (7), v,9 (1), iv,10 (10) or iv,10,i (3) rays. Pelvic-fin origin at vertical through posterior limit of dorsal-fin base. Pelvic fin with slightly convex margin and i,5 (27) rays; tip of adpressed fin not reaching anal-fin origin. Pectoral fin with I,9 (5) or I,9,i (22) rays; posterior fin margin slightly concave; anterior spine margin smooth, posterior margin with 8–13 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 prominent pale midlateral line. All fins with brown fin rays, and diffuse melanophores on fin 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 tip of lobes hyaline. Maxillary and nasal barbels brown dorsally, beige ventrally. Mandibular barbels beige. Shortly after fixation, body bluish dark brown, stripes yellowish white (see Kottelat et al., 1993: pl. 37, as G. platypogonides ).

Habitat. Glyptothorax schmidti is found in upper portions of river drainages, typically in streams and rivers with a strong current and a substrate of rocks and gravel.

Distribution. Glyptothorax schmidti is known from river drainages in northern Sumatra (Deli River and neighboring drainages) and the Malay Peninsula, on the west coast from Tenasserim River southwards to Klang River drainages and on the east coast from Tha Di River southwards to Pahang River drainages ( Fig. 36 ).

Comparisons. Besides G. famelicus and G. ketambe (already compared with G. schmidti in the diagnosis) and which share the prominent pale mid-dorsal and midlateral stripes, there are six other congeners known from the Malay Peninsula and Sumatra: G. amnestus , G. f u s c u s, G. keluk , G. platypogonides , G. prashadi and G. plectilis . Glyptothorax schmidti further differs from all of these five species in having a longer dorsal-to-adipose distance (23.9–28.1% SL vs. 14.8–23.6), from G. amnestus in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus, a more slender body (depth at anus 11.4–15.7% SL vs. 15.3–20.6) and a more slender caudal peduncle (depth 5.8–8.7% 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 11.4–15.7% SL vs. 15.6–20.7), and from G. k el u k in having a shorter dorsal-fin spine (8.9–14.9% SL vs. 16.0–20.1), a straight (vs. convex) dorsoposterior margin of the adipose fin and a longer post-adipose distance (18.9–22.0% SL vs. 15.2–16.7). It is further distinguished from G. platypogonides in having a smaller eye (5–10% HL vs. 11–14), shorter dorsal-fin spine (8.9–14.9% SL vs. 15.6–19.3), from G. plectilis in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus and having a more slender body (depth at anus 11.4–15.7% SL vs. 15.3–18.8) and caudal peduncle (depth 5.8–8.7% SL vs. 8.4–10.6), and a longer post-adipose distance (18.9–22.0% SL vs. 14.0–17.6), and from G. prashadi in having a narrower head (16.7–20.4% SL vs. 20.2–22.8), a shorter dorsal-fin spine (8.9–14.9% SL vs. 14.2–17.3), a concave (vs. straight) margin of the dorsal fin, a more slender body (depth at anus 11.4–15.7% SL vs. 15.8–18.8) and a more slender caudal peduncle (5.8–8.7% SL vs. 8.3–10.3).

Among the remaining Sundaic congeners, G. schmidti further differs from G. decussatus in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus, a shorter dorsal-fin spine (8.9–14.9% SL vs. 16.0–17.3), a longer dorsal-to-adipose distance (23.9–28.1% SL vs. 18.6-21.2), a longer post-adipose distance (18.9–22.0% SL vs. 16.2–17.5), and a more slender caudal peduncle (depth 5.8–8.7% SL vs. 10.3–10.9), from G. exodon in having the premaxillary tooth band approximately half (vs. almost entirely) exposed when the mouth is closed and a smaller eye (diameter 5–10% HL vs. 10–13), and from G. major in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus, a shorter predorsal length (31.6–36.9% SL vs. 36.7–41.6), a longer and more slender caudal peduncle (depth 2.2–3.0 times in its length vs. 1.6–2.2). It is further distinguished from G. nieuwenhuisi in having a longer dorsal-to-adipose distance (23.9–28.1% SL vs. 16.7–21.7), from G. pictus in having a shorter dorsal-fin spine (8.9–14.9% SL vs. 15.4–20.9), a more slender body (depth at anus 11.4–15.7% SL vs. 15.4–20.2) and caudal peduncle (depth 5.8–8.7% SL vs. 8.4–10.9), and from G. platypogon in having a more slender body (depth at anus 11.4–15.7% SL vs. 15.4–19.0), a straight (vs. convex) dorsoposterior margin of the adipose fin, a longer post-adipose distance (18.9–22.0% SL vs. 14.6–17.6) and caudal peduncle (18.7–21.4% SL vs. 15.5–18.2). Glyptothorax schmidti further differs from G. robustus in having (vs. lacking) a medial pit in the thoracic adhesive apparatus, a shorter predorsal length (31.6–36.9% SL vs. 36.7–40.0) and a longer dorsal-to-adipose distance (23.9– 28.1% SL vs. 16.9–20.4), and from G. stibaros in having a shorter predorsal distance (31.6–36.9% SL vs. 39.1– 42.8), a smooth (vs. serrated) posterior margin of the dorsal-fin spine, shorter dorsal- (8.9–14.9% SL vs. 15.9–20.4) and pectoral-fin spines (14.0–18.3% SL vs. 18.1–22.2), a shorter adipose-fin base (10.1–14.9% SL vs. 14.6–17.8), longer dorsal-to-adipose (23.9–28.1% SL vs. 15.1–21.3) and post-adipose (18.9–22.0% SL vs. 15.7–18.3) distances, and a more slender body (depth at anus 11.4–15.7% SL vs. 15.6–20.6).

Given that Glyptothorax species from the Malay Peninsula are also known to occur in the rivers draining the southern face of the Cardamom Mountains (in southeastern Thailand and presumably southwestern Cambodia), it is necessary to compare G. schmidti with G. coracinus , a species known from the short coastal drainages draining the western face of the Krâvanh (Cardamom) Mountains and Dâmrei (Elephant) Mountains in southwest Cambodia that is very similar in overall morphology and color pattern. Although Ng & Rainboth (2008) distinguished G. coracinus from G. schmidti (as G. siamensis ) in having a smaller eye (6–7% HL vs. 8–11), the results of our study indicate that the eye diameter of the two species overlap completely (5–10% HL for G. schmidti vs. 6–7 for G. coracinus ). However, G. coracinus lacks anastomosing striae on the thoracic adhesive apparatus (vs. anastomising striae present), and has both a less tapering body than G. schmidti (caudal peduncle depth 1.7 times in body depth at anus vs. 1.8–2.4) as well as darker dorsal, pectoral, pelvic and caudal fins due to the presence of brown pigmentation on almost the entire dorsal surfaces of these fins (vs. pigmentation absent or only partially present on some fin rays); it is on the basis of these characters that we regard the two species as distinct.

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 36. Map showing collection localities of Glyptothorax prashadi, G. schmidti and G. stibaros.

FIGURE 38. Glyptothorax schmidti, CMK 4536, 74.6 mm SL; Sumatra: Sumatera Utara, Sungai Seruai. Dorsal, lateral and ventral views. Dorsal, lateral and ventral views.

Tables

TABLE 16. Morphometric data for Glyptothorax schmidti (n = 27).

	Range	Mean±SD
Standard length (mm)	43.9–111.8
%SL
Predorsal length	31.6-36.9	34.3±1.52
Preanal length	63.3-69.2	65.4±1.45
Prepelvic length	45.2-49.8	47.1±1.51
Prepectoral length	17.9-22.4	19.7±1.33
Length of dorsal-fin base	10.2-13.4	12.1±0.88
Dorsal-fin spine length	8.9-14.9	12.8±1.43
Length of anal-fin base	13.9–17.0	15.5±0.89
Pelvic-fin length	15.1–19.5	17.1±1.07
Pectoral-fin length	20.1–24.8	21.9±1.25
Pectoral-fin spine length	14.0–18.3	15.6±1.00
Caudal-fin length	24.5–30.5	27.3±1.67
Length of adipose-fin base	10.1–14.9	12.3±1.15
Dorsal to adipose distance	23.9–28.1	25.6±1.17
Post-adipose distance	18.9–22.0	20.3±0.81
Length of caudal peduncle	18.7–21.4	20.1±0.79
Depth of caudal peduncle	5.8–8.7	7.5±0.81
Body depth at anus	11.4–15.7	13.8±1.09
Body depth at dorsal-fin origin	15.4–18.1	16.6±1.07
Head length	22.6–28.0	24.3±1.19
Head width	16.7–20.8	19.1±1.00
Head depth	12.5–16.7	14.1±1.06
%HL
Snout length	44–52	48±2.3
Interorbital distance	27–33	30±1.5
Eye diameter	5–10	8±1.1
Nasal barbel length	14–28	21±3.7
Maxillary barbel length	76–106	94±7.8
Inner mandibular barbel length	27–37	32.±2.5
Outer mandibular barbel length	42–57	49±3.9