Glyptothorax pictus, Ng, Heok Hee & Kottelat, Maurice, 2016

Ng, Heok Hee & Kottelat, Maurice, 2016, The Glyptothorax of Sundaland: a revisionary study (Teleostei: Sisoridae), Zootaxa 4188 (1), pp. 1-92 : 49-54

Glyptothorax pictus new species

( Fig. 25 , 27 )

Type material. Holotype: MZB 17218, 54.2 mm SL; Borneo: Kalimantan Tengah, Sungai Teweh above Desa Lampeong II, Barito River drainage; A. Tjakrawidjaja & A. Mun’im, 2 October 1995.

Paratypes: BORNEO: ZRC 53523 (1), 59.9 mm SL; Kalimantan Tengah: stream at km 57 logging road at buffer zone of Bukit Raya-Bukit Baka National Park, Katingan River drainage, 0°4'4"S 112°16'57"E; H. H. Tan et al., 11–12 August 2007 . MZB 6995 (70), 17.8–30.8 mm SL; Kalimantan Tengah, Kecamatan Laung Tuhup, Sungai Laung at Desa Maruwei, Barito River drainage; A. Tjakrawidjaja, D. Siebert & O. Crimmen, 15–18 July 1992 . ZRC 53522 (1), 76.1 mm SL; Kalimantan Tengah: Sungai Baha’e, km 64 on logging road at buffer zone of Bukit Raya-Bukit Baka National Park, Katingan River drainage, 0°47'35.6"S 112°19'13.2"E; H. H. Tan et al., 12–13 August 2007 . ZRC 53521 (2), 45.9–49.2 mm SL; Kalimantan Tengah: stream at buffer zone of Bukit Raya-Bukit Baka National Park, Katingan River drainage, 0°44'55"S 112°15'51"E; H. H. Tan et al., 12–13 August 2007 . BMNH 1998.9.30.20–34 (15), 27.8–57.2 mm SL; Kalimantan Tengah, Sungai Kias at Desa Tambaba, Barito River drainage; A. Tjakradwidjaja & A. Mun’im, 2 October 1995 . BMNH 1998.9.30.282–310 (29), 23.6–54.3 mm SL; data as for holotype . MZB 1302 (1), 68.0 mm SL; Kalimantan Selatan: Batang Alai at Datar Alai, Barito River drainage; M. A. Rifai, 22 October 1972 . MZB 1306 (2), 59.8–79.6 mm SL; same locality; M. A. Rifai, 25 October 1972 .

Diagnosis. Glyptothorax pictus differs from all Sundaic congeners except for G. decussatus in having a color pattern consisting of a brown or brownish gray body with prominent dark vertical bars at the level of the adiposefin base and the base of the caudal fin (vs. without distinct vertical markings on body). It is distinguished from G. decussatus in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus and the pelvic fins not reaching (vs. reaching) the base of the first anal-fin ray when adpressed. The only Sundaic congeners with a vaguely similar color pattern are G. exodon and G. platypogonides ( Figs. 10 and 31 ), but G. p i c t u s differs from G. exodon in having the premaxillary toothband approximately half (vs. almost entirely) exposed when the mouth is closed and a shorter dorsal-to-adipose distance (14.7–21.4% SL vs. 21.9–26.3), and from G. platypogonides in having a deeper body (depth at anus 15.4–20.2% SL vs. 12.1–14.8), a deeper caudal peduncle (8.4–10.9% SL vs. 6.5–7.9) and a longer adipose-fin base (13.6–18.9% SL vs. 10.7–13.7). The following unique combination of characters further distinguishes G. pictus from Sundaic congeners: anteromedial striae in thoracic adhesive apparatus absent; pectoral-fin spine length 17.3–22.9% SL; dorsal-fin spine length 15.4–20.9% SL; margin of dorsal fin concave; straight dorsoposterior margin of adipose fin; caudal peduncle depth 8.4–10.9% SL; caudal fin without prominent dark longitudinal stripes running through each lobe; and absence of prominent pale midlateral stripe on body.

Description. Morphometric data in Table 10 . 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 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 15+17=32 (1), 17+15=32 (1), 16+17=33 (5), 17+16=33 (4), 16+18=34 (3), 17+17=34* (26), 18+16=34 (3) or 18+17=35 (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 ventral margin of posttemporal to isthmus. First branchial arch with 2+6 (2), 2+7* (11), 3+6 (2), 2+8 (2) or 3+7 (3) 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 narrow keratinized striae in an elongate ovate field extending from isthmus to just beyond posterior limit of pectoral-fin base ( Fig. 3 j). Anteromedial striae present. Narrow, v-shaped medial pit on posterior half.

Dorsal fin located above anterior third of body, with I,6 (24) 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 (24) 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,7,i (4), iv,8 (4), iv,8,i (10), iv,9* (4), iv,9,i (1) or iv,10 (1) rays. Pelvic-fin origin at vertical through posterior limit of dorsal-fin base. Pelvic fin with slightly convex margin and i,5 (24) rays; tip of adpressed fin not reaching anal-fin origin. Pectoral fin with I,7,i (13), I,8 (9), or I,8,i* (2) rays; posterior fin margin slightly concave; anterior spine margin smooth, posterior margin with 5–14 (holotype =13) serrations.

Coloration. In 70% ethanol: dorsal and lateral surfaces of head and body brown or brownish gray, fading to beige or light gray on ventral surfaces. Dorsal and lateral surfaces of head and predorsal region frequently with numerous small darker spots scattered throughout. Mid-dorsal region between base of last dorsal-fin ray and origin of adipose fin with very diffuse pale band. Caudal peduncle slightly paler. Two dark brown to brownish gray vertical bands present on body: one between adipose- and anal-fin bases and other at base of caudal fin. All fins with fin rays proximally brown or brownish gray, becoming hyaline more distally, and diffuse melanophores on fin membranes. Pectoral and pelvic fins with brown or brownish gray on base of fin rays and hyaline posterior twothirds. Pelvic fin with additional diffuse brown band on middle third of pelvic fin present in some individuals. Anal fin with brown or brownish gray base, with diffuse brown or brownish gray spot on anterior third of fin in some individuals. Adipose fin brown or brownish gray with hyaline distal margin. Each caudal-fin lobe with numerous small brown spots finely scattered throughout fin in some individuals; in other individuals, an irregular, elongate brown blotch present on about half of outer fin rays on each lobe; most of inner rays of lobes hyaline. Maxillary and nasal barbels brown or brownish gray dorsally, light gray or beige ventrally. Mandibular barbels light gray or beige.

Distribution. Glyptothorax pictus is known from the river drainages in southern Borneo, from the Katingan River drainage eastwards to the Barito River drainage ( Fig. 26 ).

Comparisons. Besides G. decussatus and G. exodon (which has already been compard to G. pictus in the diagnosis), there are three other congeners known from Borneo: G. m a j o r, G. nieuwenhuisi and G. stibaros . Besides its color pattern, G. p i c t u s is further distinguished from G. m a j o r in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus, from both G. nieuwenhuisi and G. stibaros in having a deeper caudal peduncle (8.4–10.9% SL vs. 6.9–8.4), and from G. stibaros in having a smooth (vs. denticulate) posterior margin of the dorsal-fin spine.

Among the remaining Sundaic congeners, G. p i c t u s further differs from G. amnestus in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus, from G. famelicus in having a deeper body (depth at anus 15.4–20.2% SL vs. 11.4–14.3), a deeper caudal peduncle (8.4–10.9% SL vs. 5.8–7.3) and lacking (vs. having) a prominent pale midlateral stripe on the body, from G. f u s c u s and G. prashadi in having a concave (vs. straight) margin of the dorsal fin and from G. keluk in having a straight (vs. convex) dorsoposterior margin of the adipose fin. It is further distinguished from G. ketambe in having a longer pectoral-fin spine (17.3–22.9% SL vs. 14.3– 16.6), a deeper body (depth at anus 15.4–20.2% SL vs. 12.7–15.3), a shorter dorsal-to-adipose distance (14.7–21.4% SL vs. 21.5–25.6) and lacking (vs. having) a prominent pale midlateral stripe on the body, from G. platypogon in having a longer pectoral-fin spine (17.3–22.9% SL vs. 13.6–17.9) and a straight (vs. convex) dorsoposterior margin of the adipose fin and from G. plectilis in lacking (vs. having) anteromedial striae in the thoracic adhesive apparatus. Glyptothorax pictus further differs from G. robustus in having (vs. lacking) a medial pit in the thoracic adhesive apparatus, a deeper caudal peduncle (8.4–10.9% SL vs. 6.6–8.3) and lacking (vs. having) prominent dark longitudinal stripes running through each lobe of the caudal fin, and from G. schmidti in having a longer dorsal-fin spine (15.4–20.9% SL vs. 8.9–14.9), a deeper body (depth at anus 15.4–20.2% SL vs. 11.4–15.7), a deeper caudal peduncle (8.4–10.9% SL vs. 5.8–8.7) and lacking (vs. having) a prominent pale midlateral stripe on the body.

Remarks. Specimens of G. pictus from the Katingan River drainage appear to have a more robust body and a steeper predorsal profile ( Fig. 27 ). However, as we were unable to identify any other differences between material from the Katingan and Barito river drainages, we consider the two populations conspecific.

We are also aware of a Glyptothorax species with a color pattern very similar to G. pictus known from the Sesayap River drainage in northeastern Borneo ( Fig. 28 ). However, the thoracic adhesive apparatus in the Sesayap population possesses anteromedial striae not seen in G. pictus . Until material is available for study, we identify this species as G. aff. pictus .

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 10. Glyptothorax exodon, BMNH 1982.3. 29.190, paratype, 63.2 mm SL; Borneo: Kalimantan Barat, Sungai Pinoh. Dorsal, lateral and ventral views.

FIGURE 25. Glyptothorax pictus, MZB 17218, holotype, 54.2 mm SL; Borneo: Sungai Teweh. Dorsal, lateral and ventral views.

FIGURE 26. Map showing collection localities of Glyptothorax pictus, G. plectilis and G. robustus.

FIGURE 27. Glyptothorax pictus, ZRC 53522, paratype, 76.1 mm SL; Borneo: Katingan River drainage.

FIGURE 28. Glyptothorax aff. pictus, ca. 95 mm SL, Borneo: Kalimantan Utara, Sungai Setulang, 3 ° 25 ' 25.8 " N 116 ° 27 ' 38.8 " E, specimen not preserved. Photograph by Martin Holland and Frank van Veen.

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

Tables

TABLE 10. Morphometric data for Glyptothorax pictus (n = 24).

	Holotype MZB 17218	Range	Mean±SD
Standard length (mm) %SL	54.2	45.9–76.1
Predorsal length Preanal length Prepelvic length	39.3 68.3 51.7	35.1–40.4 64.5–71.7 48.4–53.5	38.2±1.63 68.2±1.75 51.4±1.43
Prepectoral length Length of dorsal-fin base Dorsal-fin spine length	23.4 13.8 17.9	19.5–25.8 12.7–16.5 15.4–20.9	23.1±1.95 14.4±1.00 17.6±1.69
Length of anal-fin base Pelvic-fin length Pectoral-fin length	15.5 15.3 22.9	13.4–18.0 13.7–17.5 21.9–27.4	15.5±1.12 15.9±1.01 24.5±1.62
Pectoral-fin spine length Caudal-fin length Length of adipose-fin base	19.7 28.4 16.2	17.3–22.9 24.8–30.6 13.6–18.9	20.1±1.77 27.6±1.51 15.4±1.25
Dorsal to adipose distance Post-adipose distance Length of caudal peduncle	17.0 16.8 16.6	14.7–21.4 15.1–19.8 16.2–21.1	18.6±1.87 17.6±1.12 18.6±1.40
Depth of caudal peduncle Body depth at anus Body depth at dorsal-fin origin	9.0 17.2 20.5	8.4–10.9 15.4–20.2 17.4–21.4	9.3±0.66 17.4±1.27 19.6±1.43
Head length Head width Head depth	27.3 20.5 15.7	25.7–30.1 17.7–22.8 14.9–17.5	27.5±1.24 20.2±1.30 16.0±0.80
%HL Snout length Interorbital distance	49 27	46–52 26–32	49±2.1 28±1.7
Eye diameter Nasal barbel length Maxillary barbel length	11 19 93	8–13 17–28 73–107	11±1.2 21±2.5 88±8.9
Inner mandibular barbel length Outer mandibular barbel length	32 49	28–41 43–63	34±3.3 52±6.0