Rasbora cf. sumatrana 1: Kottelat & Vidthayanon, 1993: 164 .
Rasbora rheophila, a new species of fish from northern Borneo (Teleostei: Cyprinidae)
Kottelat, Maurice
Revue suisse de Zoologie
2012
2012-03-31
119
1
77
87
4RLGW
2713768
Kottelat, 2012
Kottelat
2012
[151,357,270,294]
Actinopterygii
Cyprinidae
Rasbora
Animalia
Cypriniformes
1
78
Chordata
species
rheophila
sp. nov.
Figs. 1-2
Rasboracf. sumatrana1: Kottelat & Vidthayanon, 1993: 164.
HOLOTYPE: IRSNB 874, 59.4 mmSL; Borneo: Sabah: Sungai Pangakatan(a tributary of Sungai Liwagu), near Ranau on road to hot spring; Leopold III& J. P. Gosse, 8 October 1971. PARATYPES: IRSNB 875[ex 17554], 83, 37.8-58. 8 mmSL; CMK 21901, 10, 39.7-58. 3 mmSL; same data as holotype.– CMK 9461, 5, 20. 0-57. 5 mmSL; Borneo: Kalimantan Timur: Sebukudrainage: Sungai Bantul at Bantul logging camp, draining to Tulit; 4°08.9'N 116°48.3'E; M. Kottelat& P. McKee, 10 February 1993.– MHNG 2542.37, 9, 20.1-39.0 mm SL; Borneo: Sabah: Long Pa Sia; about 60 kmSouth-East of Lawas, 135 kmsouth of Beaufort, tributary of Sungai Padas; 4°25'N 115°43'E; J. Binggeli, October 1992.– ZRC 47505, 1, 68.4 mmSL; Borneo: Sabah: Kota Marudu: Marak Parak, Sungai Kinarom, Kampung Loguhang, about 6 kmdownstream of Serinsim Station( 6°19.733'N 116°44.403'E, 120 masl); Tan H. H.et al., 15 December 2000.
DIAGNOSIS: Rasbora rheophilais distinguished from all its congeners by the combination of the following characters: body slender, depth 21-25 % SL (4.0-4.7 times in SL); predorsal length 49-56 % SL, dorso-hypural distance, when carried forward, falling before nostrils; 14 circumpeduncular scale rows; 31-34 + 2-3 lateral line scales; rounded snout; a dark lateral stripe from head to end of hypural plate, over axial streak; caudal fin with a greyish to black posterior margin, restricted to upper lobe in some populations; caudal peduncle 1.9-2.2 times longer than deep; 18-19 + 18-20 = 36-38 vertebrae.
DESCRIPTION: General appearance is shown in Figures 1-2and morphometric data of holotypeand 8 paratypesare given in Table 1. Dorsal fin with 2 simple and 7-8½ branched rays; origin above lateral line scale 12 (1), 13 (7) or14 (2). Pectoral fin slightly falcate, with 14-16 rays; a small axillary lobe present. Pelvic fin slightly pointed, with 9 rays; axillary scale present. Anal fin with 3 simple and 5½ branched rays. Caudal fin with 10+9 principal rays, 9+8 being branched. Caudal peduncle 1.94- 2.24 times longer than deep. 31 (1), 32 (2), 33 (4) or 34 (2) scales along lateral line + 2-3 pored scales on caudal-fin base. Lateral line complete. 12 (1), 13 (5) or 14 (4) predorsal scales, ½4/1/2½ scales in transverse line, ½4/1/1½ scales in transverse line on caudal peduncle (½5/1/1½ in holotype), 1½ scales between lateral line and pelvicfin origin. Vertebral formula: 18+18=36 (1), 18+19=37 (4), 18+20=38 (1), 19+18=37 (5), and 19+19=38 (8) (from Kottelat & Vidthayanon, 1993: 164). A few scattered and irregularly shaped tubercles on lower jaw of Sebuku specimens. COLORATION: Thecolour pattern of the Pangakatanand Sebukupopulations are illustrated in Figures 1-2. Adark stripe from head to end of hypural plate, over axial streak. Axialstreak extending forward to gill opening. Lateralstripe black below axial streak and much paler, brownish or greyish, above. A blackish mid-dorsal stripe from nape to caudal-fin base. Dorsumgreyish, with crescentic paler marks parallel to posterior scale margins. A narrow and faint line of black pigments above anal-fin base. Bellypale yellowish, with a few brown crescentic marks on anterior medio-lateral scales. In Sebukuspecimens, caudal fin with a dark grey posterior margin, broader near the tip of the lobes; in Pangakatanspecimens, margin narrow or absent on lower lobe and broader and more intense on upper lobe. In Kinaromspecimen, margin very faint on lower lobe and narrow on upper lobe. Otherfins hyaline. Thepaler coloration of specimen in Figure 2compared to that in Figure 1bis apparently due to it having been collected in a rainy period in murky water. FIG. 1 Rasbora rheophila, Borneo: Sabah: Ranau; a, IRSNB 874, holotype, 59.4 mmSL (photographed in 2011); b, CMK 21901, paratype, 58.3 mmSL (photographed in 1985). FIG. 2 Rasbora rheophila, CMK9641, paratype, 57.5 mmSL; Borneo: Kalimantan Timur: Sebukudrainage. Live coloration not observed due to very heavy rains at time of collecting of Sebuku specimens. When first observed at day light (following day), specimens with same colour pattern as described above.
DISTRIBUTION: Rasbora rheophilais known from Sabah(Labuk, Padas and Kinarom drainages) and Kalimantan Timur(Sebuku drainage) ( Fig. 3). It is expected to occur in the headwaters of other drainages of Sabah, as well as in the northernmost part of Kalimantan Timur(for example in Sembakung drainage, which originates in Sabah).
HABITAT: The Sebuku specimens were obtained from a high gradient mountain stream in a large and deep pool somewhat isolated from the main stream and with counter current. The Ranau specimens were collected at an altitude of ca. 550 masl. The Kinarom specimen was collected at 120 masl, in a fast flowing hill stream draining from the northern area of Mount Kinabalu.
ETYMOLOGY: From the Greek rheos, stream and philos, loving. Treated as an adjective.
REMARKS: The known populations of R. rheophiladiffer slightly in coloration of the caudal fin (see above and Figs. 1-2), head length and predorsal length (see Table 1). Part of the differences in coloration (not pattern) between the specimens on Figures 1and 2results from the holotypehaving been fixed about 14 ( Fig. 1b) and 40 years ( Fig. 1b) before photography and stored in ethanol denaturated with campher, while the specimen in Figure 2was photographed about 2 weeks after fixation, while still in formalin. Also, this last specimen was collected in a rainy period and in murky water, while the intensity of the pattern of the specimens in Figure 1bsuggests that they were collected in clear water. I cannot, however, exclude the possibility that they actually might represent two species. Samples from intermediate areas are needed to investigate this possibility. I have observed that the fish populations from eastern and northern Borneo show much greater interdrainage variation than those of the remaining drainages of the island. This seems to reflect more difficult connections between the drainages. During glacial periods, when the sea level decreased and exposed the Sunda Shelf around western and southern Borneo and between Borneo, Java, Sumatraand the Malay Peninsula, connections were established between these rivers, resulting in a few large drainages ( Molengraaff & Weber, 1919; de Beaufort, 1951; Sathiamurthy & Voris, 2006), allowing gene flow and contributing to retain some homogeneity within species. Along the coasts of eastern and northern Borneo, the continental shelf is very narrow and the structure of the river network is quite simple, made of many relatively short rivers. Even with the lowered sea level, these small river drainages remained largely unconnected during glacial periods, allowing differentiation of the respective populations. In several cases, the apparent random interdrainage variability observed today is likely to turn out as interspecific differences when more material will become available (more samples from each drainage, and from several localities within each drainage). Similar variability patterns have been observed in Puntius sealei(Herre, 1933), Nematabramisspp., Glyptothoraxspp., Nemacheilus longipectoralisPopta, 1905, N. olivaceusBoulenger, 1894, etc. (pers. obs.). The same mechanism also explains the high endemism level in the drainages of the southwestern (Indian Ocean) slope of Sumatra(e.g. Ng & Hadiaty, 2005, 2008; Hadiaty & Siebert, 1998, 2001; Lumbantobing, 2010) or allows to predict that dozens of species still await discovery in the many coastal drainages isolated by steep hills and the absence of continental shelf. Using Brittan's (1954: 205)key, R. rheophilafalls within a group of species with 14 circumpeduncular scale rows, the dorso-hypural distance falling in front of the posterior margin of the eye when carried forward, 1 or 1½ scale row between the lateral line and the origin of the pelvic fin and a continuous dark midlateral stripe from the gill opening to the base of the caudal fin. This group includes R. myersi Brittan, 1954(erroneously synonymised with R. dusonensis(Bleeker, 1850)by Kottelat, 1991: 187), R. argyrotaenia(Bleeker, 1849)and R. philippina(Günther, 1864). Rabora hubbsi Brittan, 1954also has 14 circumpeduncular scales rows, the dorso-hypural distance falling at or in front of the tip of the snout, 1½ scale rows between the lateral line and the origin of the pelvic fin, but the midlateral stripe is more intense posteriorly, with an abrupt transition to the much diffuse anterior portion (vs. equal intensity along whole length of the stripe or with gradual change in these species) and it belongs to the R. trifasciatagroup. Rasbora dusonensisand R. tornieriAhl, 1922[erroneously synonymised by Kottelat, 1991: 187] also have 14 circumpeduncular scale rows but the dorso-hypural distance falls behind the posterior margin of the eye when carried forward. Rasbora rheophilais also distinguished from them by having a hyaline caudal fin with a grayish posterior margin (vs. bright yellow with a broad black margin in R. dusonensisand deep red in R. tornieri; pers. obs.). TABLE 1. Rasbora rheophila, morphometric data of holotype(IRSNB 874) and 8 paratypes. IRSNB IRSNB 875 CMK 9461 874 Standardlength (mm) 59.4 59.1 58.8 58.1 52.0 57.5 57.2 49.7 48.8 Percent of standard length Totallength 131.3 130.0 138.4 130.3 130.4 133.0 131.1 132.4 132.6 Headlength 25.3 25.9 24.9 25.1 25.0 23.7 23.0 23.9 23.8 Predorsallength 52.2 53.1 55.9 52.0 51.7 49.7 49.0 49.7 49.8 Prepelviclength 48.8 48.4 50.5 48.7 47.3 47.5 45.8 47.7 47.1 Preanallength 67.8 67.7 71.7 67.3 65.6 67.0 65.9 66.6 65.8 Bodydepthatpelvicorigin 22.9 25.0 24.7 23.9 21.0 23.8 22.0 21.9 21.7 Depthofcaudalpeduncle 11.3 11.5 12.2 11.5 11.0 11.8 11.5 11.7 11.1 Lengthofcaudalpeduncle 21.9 25.0 24.9 24.3 23.3 24.0 25.9 23.3 24.6 Bodywidthbehindpectoralbase 11.4 11.8 2.5 11.9 11.2 11.7 11.5 11.5 11.1 Lengthofdorsalfin 21.7 20.6 22.9 21.0 22.3 24.9 22.6 24.3 23.4 Lengthofanalfin 16.5 16.4 17.7 16.5 17.7 19.7 17.5 18.1 18.4 Lengthofpelvicfin 15.8 15.7 16.5 15.7 15.0 19.0 17.0 17.3 16.4 Lengthofpectoralfin 19.2 19.1 21.0 19.6 19.2 21.4 19.2 19.9 19.5 Lengthofuppercaudallobe 30.8 29.8 32.6 30.1 28.3 32.9 31.3 31.8 32.4 Lengthofmediancaudalrays 15.5 15.2 14.7 13.6 15.4 17.9 15.0 14.7 16.2 Lengthoflowercaudallobe 31.6 29.1 33.3 31.3 31.0 38.3 34.6 33.4 31.6 Percent of head length Head depth at nape 65 63 65 66 65 65 65 67 68 Snout length 27 27 29 27 28 28 30 29 28 Eye diameter 31 31 32 33 31 33 33 33 32 Interorbital width 32 32 36 32 32 35 36 34 32 Rasbora rheophilais distinguished from R. philippina, a species endemic to Mindanao, Philippines, by its slender body (depth 4.0-4.7 times in SL, vs. 3.1-3.8; Brittan, 1954: 128) and a different appearance (see Brittan, 1954: 128, fig. 28). As presently recognised, R. argyrotaeniais a species widely distributed in Java, Sumatra, Borneo and the Malay Peninsula ( Brittan, 1954). In fact, it is a complex assemblage, which will eventually be shown to include several species ( Kottelat & Vidthayanon, 1993). The typelocality of R. argyrotaeniais in Java, the typeseries is a composite of several localities and possibly several species. A comparison of material from East Java(an area part of the typelocality) with material from southern and eastern Borneoshow they are specifically distinct (unpubl., pers.obs.) and that the name R. vaillantii(Popta, 1905)( typelocality: Borneo: Mahakam drainage) is the oldest available name for the species from Borneo ( Fig. 4). The known range of R. vaillantiipossibly extends in the eastern half of Borneo from the Barito to the Sebuku drainages. Rasbora rheophilaand R. vaillantiioccur in sympatry in the Sebuku drainage (but not in syntopy). The two species have very different habitats (mountain stream for R. rheophila, lowland slow flowing streams and rivers for R. vaillantii), they differ in head shape and general appearance (compare Figures 1, 2and 4), a more forward dorsal fin (dorso-hypural distance, when carried forward, falling in front of nostril, vs. on eye), and number of vertebrae (18-19 + 18-20 = 36-38, vs. 17-18 + 14-15 = 31-33 [Mahakam], 17+16=33 [Sebuku] in R. vaillantii]). Material of R. vaillantii(identified as R. argyrotaenia) and R. laticlaviafrom the Barito also has 32-34 total vertebrae ( Siebert & Richardson, 1997). Rasbora rheophilaalso differs from R. vaillantiiby the structure of the midlateral stripe. In R. rheophilathe midlateral stripe is made of a black or dark brown part below the axial streak, and a grey part above. This corresponds to the dark lateral stripe and dorso-lateral stripe, respectively, of Brittan (1954). These two stripes are contiguous, while in most other species of Rasborathe two stripes are separated by a paler stripe. In R. vaillantii, the dorso-lateral stripe is very narrow, indistinct posteriorly and separated from the 'dark lateral stripe' by a narrow paler area). Rasbora rheophiladiffers from R. myersi, also a species widely distributed in Southeast Asia but apparently absent from northern and eastern Borneo, by having a slender body (depth 4.0-4.7 times in SL, vs. 3.4-4.6), more vertebrae (18-19 + 18-20 = 36-38, vs. 16-19 + 13-15 = 31-33), a more rounded head, more forward dorsal fin (dorso-hypural distance, when carried forward, falling in front of nostril, vs. on eye), and more lateral line scales (31-34 + 2-3, vs. 29-31 + 2-3). Morphometric data of R. myersiare from Brittan (1954: 119). Rasbora borneensisBleeker, 1860, was considered a synonym of R. argyrotaeniaby Brittan (1954)and revalidated by Roberts (1989: 71). It is also a slender species with relatively small head. Rasbora rheophilais distinguished from R. borneensisby having more vertebrae (18-19 + 18-20 = 36-38, vs. 18-19 + 16-17 = 35), a more rounded head, a very narrow adipose eye-lid (vs. broad), more forward dorsal fin (dorso-hypural distance, when carried forward, falling in front of nostril, vs. on eye or just behind), fewer predorsal scales (12-14, vs. 15-16), a somewhat longer head (3.9- 4.3 times in SL, vs. 4.2-4.5; Roberts, 1989: 72), and structure of the midlateral stripe (black lower half adjacent to axial streak on all its length, vs. running slightly below axial streak in front of dorsal-fin origin). Rasbora leptosoma(Bleeker, 1855), described from Lahat ( Sumatra) and known only from two poorly preserved syntypes, is possibly a senior synonym of R. borneensisbut fresh topotypes are needed to reach a reliable conclusion. FIG. 4 Rasbora vaillantii, CMK9523, 69.7 mmSL mm SL; Borneo: Kalimantan Timur: Sebuku drainage. Rasbora rheophilashares with R. volziiPopta, 1905( Fig. 5) and R. everettiBoulenger, 1895( Fig. 6) the vertebrae count of 36-38; all other species of the R. sumatranagroup have 31-35 (see Kottelat & Vidthayanon, 1993, for vertebrae counts of most species of Rasbora). Rasbora rheophiladiffers from R. everettiby its more rounded snout (compare Figs. 1, 2and 6) and interorbital area, more lateral line scales (31-34 + 2-3, vs. 27-30 + 2-3), more circumpeduncular scales (14 vs. 12 [ 14 ina few specimens]), a more backward dorsal fin (dorso-hypural distance, when carried forward, falling before nostrils, vs. between nostril and eye), and the structure of the midlateral stripe (made of a black or dark brown stripe below the axial streak, and a contiguous grey stripe above vs. the black and grey stripes are separated by a narrow pale stripe above the lateral streak). Rasbora rheophiladiffers from R. volziiby snout shape (compare Figs. 1, 2and 5), snout length (27-30 % HL, vs. 30-34), interorbital distance (about equal to eye diameter, vs. 1.25-1.5 times eye diameter) and shape (rounded, vs. almost flat), colour pattern made of a continuous stripe (vs. a narrow stripe widened into an elongate blotch on the anterior part of the body and at the posterior extremity of the caudal peduncle), number of circumpeduncular scales (14, vs. 12), distribution of pigments along the posterior margin of the caudal fin (on membranes and rays, vs. on membranes only), and head length (23-26 % SL, vs. 25-27).
COMPARISON MATERIAL: Rasbora borneensis: CMK10460, 1, 64.2 mmSL; Borneo: Kalimantan Barat: Kapuas. Rasbora dusonensis: CMK20592, 25, 50.2-72. 3 mmSL; Sumatra: Sumatera Selatan: Musidrainage: Sungai Gelam. Rasbora everetti: CMK11970, 28, 15.6-53. 4 mmSL; CMK 11962, 49, 27.3- 45. 6 mmSL; Philippines: Palawan: Malatgao River.– CMK 8850, 3, 53.7-68.0 mm SL; Philippines: Palawan: Lake Manguao. Rasbora leptosoma: RMNH4981, lectotype, 67.9 mmSL; Sumatra: Lahat. Rasbora myersi: CMK10592, 10, 75.8-95. 4 mmSL; Borneo: Kalimantan Barat: Kapuasdrainage: Sungai Melawi. Rasbora tornieri: CMK20593, 28, 39.9-74. 1 mmSL; Sumatra: Sumatera Selatan: Musidrainage: Sungai Gelam. Rasbora vaillantii: CMK9523, 68, 13.1-69. 7 mmSL; Borneo: Kalimantan Timur: Sebukudrainage: Sungai Tulit. Rasbora volzii: RMNH7621, 6 syntypes, 45.1-74. 1 mmSL; Borneo: Kalimantan Timur: Mahakam drainage, Howong.– RMNH 7620, 4 paralectotypes, 80.7-91. 7 mmSL; Borneo: Kalimantan Barat: Kapuasdrainage, Bongan.– RMNH 7622, holotypeof R. v. fasciata, 100.9 mmSL; Borneo: Kalimantan Timur: Kajan[ Kayan] drainage.– ZRC 45691, 10, 22.8-78. 2 mmSL; Borneo: Kalimantan Timur: Kayandrainage, Sungai Bako.– ZRC 45627, 3, 29.9-115.0 mm SL; Borneo: Kalimantan Timur: Kayandrainage, Bahau, Sungai Batu Bayak.– ZRC 45635, 12, 19.1-86. 6 mmSL; Borneo: Kalimantan Timur: Kayan drainage, Bahau, Sungai En'ggengI'ut.– ZRC 45656, 12, 26.6-89. 2 mmSL; Borneo: Kalimantan Timur: Kayan drainage, Bahau, Lalut[= sungai] Birai. – ZRC 47524, 19, 30.2-86. 1 mmSL; CMK 17816, 4, 38.2-70. 7 mmSL; Borneo: Kalimantan Timur: Kayan drainage, Usat Aran.
4015884318
1971-10-08
IRSNB
Leopold III & J. P. Gosse
Borneo
Sungai Pangakatan
1
78
IRSNB 874
1
Sabah
holotype
4015884314
IRSNB, CMK
1
78
IRSNB 875, CMK 21901
2
paratype
4015884312
1993-02-10
CMK
M. Kottelat & P. McKee
4.1483335
Borneo
130
116.805
Sebuku
1
78
CMK 9461
1
Kalimantan Timur
4015884317
1992-10
MHNG
J. Binggeli
4.4166665
Borneo
1306
115.71667
Long Pa Sia
1
78
MHNG 2542.37
1
Sabah
4015884305
2000-12-15
ZRC
Tan H. H.
120
6.328883
Borneo
1
116.74005
Kota Marudu
1
78
ZRC 47505
1
Sabah
4015884302
[335,390,1337,1359]
Sebuku
Borneo
2
79
1
Kalimantan Timur
paratype
4015884308
[292,364,586,607]
Kayan
Borneo
8
85
1
Kalimantan Timur
holotype
4015884313
CMK
Kapuas
Borneo
8
85
CMK 10460
1
Kalimantan Barat
4015884307
CMK
Sumatera Selatan
Sungai Gelam
Musi
8
85
CMK 20592
1
Sumatra
4015884301
CMK
Philippines
Malatgao River
8
85
CMK 11970, CMK 11962
1
Palawan
4015884323
CMK
Philippines
Lake Manguao
Lake Manguao
8
85
CMK 8850
1
Palawan
4015884316
[212,1020,1379,1403]
RMNH
Lahat
8
85
RMNH 4981
1
Sumatra
lectotype
4015884320
CMK
Borneo
Sungai Melawi
Kapuas
8
85
CMK 10592
1
Kalimantan Barat
4015884310
CMK
Sumatera Selatan
Sungai Gelam
Musi
8
85
CMK 20593
1
Sumatra
4015884304
CMK
Kalimantan Timur
Sungai Tulit
Sebuku
8
85
CMK 9523
1
Borneo
4015884311
RMNH
Kalimantan Timur
Mahakam drainage
8
85
RMNH 7621
6
Borneo
syntype
4015884322
RMNH
Kalimantan Barat
9
86
Bongan
Kapuas
8
85
RMNH 7620
4
Borneo
paralectotype
4015884306
RMNH
Kalimantan Timur
Kajan
9
86
RMNH 7622
1
Borneo
holotype
4015884321
2010-08-22
ZRC
Kalimantan Timur
Kayan
9
86
ZRC 45691
1
Borneo
4015884309
ZRC
Kalimantan Timur
Kayan
9
86
ZRC 45627
1
Borneo
4015884319
ZRC
Kalimantan Timur
Kayan drainage
9
86
ZRC 45635
1
Borneo
4015884315
ZRC
Kalimantan Timur
Kayan drainage
9
86
ZRC 45656
1
Borneo
4015884303
ZRC, CMK
Kalimantan Timur
Kayan drainage
9
86
ZRC 47524, CMK 17816
1
Borneo