Rasbora bindumatoga, Lumbantobing, Daniel N., 2014

Lumbantobing, Daniel N., 2014, Four new species of Rasbora of the Sumatrana group (Teleostei: Cyprinidae) from northern Sumatra, Indonesia, Zootaxa 3764 (1), pp. 1-25 : 14-16

Rasbora bindumatoga , new species

Figures 2 D, 6A–C, 10C

Holotype. MZB 17889, female, 47.1 mm SL, Indonesia, Sumatra, Province of Sumatera Utara (North Sumatra), Kabupaten Tapanuli Selatan, Batang Angkola River, 01°09’90”N, 099°24’83”E, D. N. Lumbantobing and D. Rudaya, 4 August 2006.

Paratypes. All from Indonesia: collected with holotype: MZB 21117, 7, 23.3–60.6 mm SL; USNM 404351, 7 (3 CS), 41.5–49.1 mm SL; ZRC 53199, 4, 25.2–46.6 mm SL. Sumatra: Province of Sumatera Utara (North Sumatra): CMK 4528, 16, 21.0– 67.6 mm SL, road from Porsea to Pulau Raya, 33 km before Pulau Raya, Bianco and M. Kottelat, 27 November. 1984; MZB 21118, 1, 57.6 mm SL, Kabupaten Tapanuli Utara, Aek Dahasan, on the road from Onanhasang to Sipirok, 01°52’25”N, 099°03’64”E, D. N. Lumbantobing, D. Rudaya and N. M. Ray, 26 July 2006; MZB 21119, 1, 72.0 mm SL; Kabupaten Toba Samosir, Aek Silang River (a tributary draining to Lake Toba), PLTA Pandan, 02°18’50”N, 098°44’51”E, D. N. Lumbantobing, D. Rudaya and N. M. Ray, 31 July 2006; USNM 390346, 1, 29.5 mm SL, Kabupaten Humbang-Hasundutan, near Doloksanggul, upstream of Aek Sibundung River, 02º15.90’N / 98º43.75’E, D. N. Lumbantobing, D. Rudaya and N. M. Ray, 31 July 2006; USNM 401208, 1, 30.2 mm SL, Kabupaten Mandailing Natal, Aek Siburiang River (a tributary of Batang Gadis River), 00°41’13”N, 099°40’11”E, D. N. Lumbantobing, D. Rudaya and N. M. Ray, 5 August 2006.

Diagnosis. Rasbora bindumatoga is distinguished from congeners by the following combination of characters: the black midlateral stripe is only represented by a rectangular subdorsal blotch without a midhumeral diffuse patch and the posterior-portion stripe, the absence of supra-anal pigmentation, and the basicaudal blotch appearing somewhat oval and lacking the basicaudal triangular patch. Rasbora bindumatoga can be distinguished further from its congeners by the combination of all the following characters listed in the description section of this species.

Description. General appearance shown in Figure 2 D. Morphometric and meristic data given in Table 2. Dorsohypural distance equal to distance from dorsal-fin origin to area between anterior portion of snout and posterior margin of pupil. Limit between head and trunk indistinct in lateral view, but more visible in smaller specimens (~ 40 mm SL). Cephalic tubercles present on males, relatively small and few in number. Tubercles distributed on dorsal surface of head from snout to occiput. Lateral line complete (all scales perforated; 24–26 + 3– 4). Dorsal-fin profile blunt with first branched ray being longest dorsal-fin ray. Dorsal-fin origin situated over 12th lateral-line scale. Tip of adpressed pectoral fin nearly reaching vertical through pelvic-fin insertion. Pelvic fin inserted below 11th lateral-line scale and distinctly anterior to vertical through dorsal-fin origin. Tip of adpressed pelvic fin extending past anus and in some specimens reaching to anal-fin origin. Anal-fin origin located below 17th lateral-line scale.

Coloration in alcohol. General body coloration in alcohol in alcohol preservation shown in Fig. 2 D. Schematic lateral body pigmentation shown in Fig. 10 C. Lachrymal region superficially pigmented with more peripherally-distributed melanophores. Dusky gular pigmentation decreasing in intensity posteriorly until reaching to vertical through rictus. Peripheral reticulation distinct and covering at maximum 4 1/2 longitudinal scale rows along dorsolateral and midlateral portions of body. Basal reticulation prominent and covering up to five longitudinal scale rows and also to dorsal scale row, with network of somewhat continuous chevron-shaped bars. Peripheral and basal reticulation overlapping at maximum on first to fifth longitudinal rows and also on dorsal scale row.

Black midlateral stripe rudimentary and replaced by black subdorsal blotch dorsally in contact with anterior portion of axial streak. Blotch rectangular or trapezoid, deeply embedded under approximately two scales at its maximum length and 1 1/2 scales at its maximum depth. Distinct black axial streak extending from hypural notch to area above subdorsal blotch, anteriorly diffusing above anterior margin of blotch, and terminating above pelvic-fin insertion. Interspersed swath of melanophores extending along and bordered dorsally by axial streak resulting in faint dusky midlateral stripe. Deeply embedded black basicaudal blotch situated on medial portion of posterior margin of hypural plate with about two scales deep and 1 1/2 scales long resulting in somewhat ovoid mark. Dusky dorsolateral stripe indistinct and visible along posterior portion of trunk bordered ventrally by axial streak. Longitudinal light area indistinct, most visible along posterodorsal portion interspersing by reticulated pigmentation. Supra-anal pigmentation absent. Subpeduncular faint. Distal edge of caudal fin pigmented with scattered melanophores resulting in narrow dusky striped margin.

Coloration in life. Ground coloration of dorsal surface of head and body pale brown, ventrolateral surface of head and body grey to whitish with silvery sheen due to guanine ( Fig. 6 A–C). Dorsum of head largely dusky, with scattered yellowish to greenish reflective patches and streaks on snout, lateral-line canals, meningeal layer, and supraorbital. Anterodorsomedial portions of operculum and upper end of gill slit with reflective yellowish patches ( Fig. 6 C). Black pigmentation on lateral body very faint and appearing bluish grey, except for reticulated pattern and basicaudal blotch relatively distinct. Yellowish reflective middorsal stripe present and distinct on dorsum of body, extending from nape to dorsal caudal peduncle ( Fig. 6 B). Reflective midlateral stripe absent. All fins hyaline. Dorsal, anal, and caudal fins with yellowish sheen on subdistal portion of branched rays.

Habitat and distribution. The specimens of Rasbora bindumatoga were collected in gravel-bottomed mountain streams and moderate-flowing turbid rivers. This species is known from the Aek Sibundung, Batang Toru, and Batang Gadis Rivers that flow into the Indian Ocean in the southern part of northwestern Sumatra, and also from a tributary draining to Lake Toba ( Fig. 8 ). It was collected sympatrically with R. api .

Etymology. The species epithet, bindumatoga , a noun in apposition, is derived from the term ‘Bindu Matoga’ in the two native languages of northern Sumatra, Mandailing and Toba, which are widely spoken throughout the distribution range of the species. By the local Mandailing and Toba people, the term ‘Bindu Matoga’ is commonly used as the name of a unique traditional ornament that has a rectangle outline. The epithet, thus, refers to the rectangular shape of the black subdorsal blotch of the species.

Figures

FIGURE 2. (A) Rasbora arundinata, holotype, MZB 17881, 74.5 mm SL, female; (B) Rasbora haru, holotype, MZB 17888, 65.4 mm SL, female; (C) Rasbora maninjau, holotype, MZB 17890, 66.9 mm SL, male; (D) Rasbora bindumatoga, holotype, MZB 17889, 47.1 mm SL, female. Bars equal 1 cm.

FIGURE 6. Photographs of living specimen of Rasbora bindumatoga, MZB 21117 (paratype).

FIGURE 8. Distribution of species of the Sumatrana group in northwestern Sumatra and adjacent regions: Rasbora arundinata (blue diamonds), Rasbora haru (green circles), Rasbora maninjau (yellow star), Rasbora bindumatoga (red asterisks), and R. vulgaris (magenta squares). Symbols with black outline are the localities of holotypes. One filled symbol may represent more than one locality.

FIGURE 10. Schematic drawing of left lateral view of three primary diagnostic lateral pigmentation characteristics of members of the Elegans subgroup: (A) R. elegans from West Johor, Peninsular Malaysia; (B) R. elegans from East Johor, Peninsular Malaysia; (C) Rasbora bindumatoga.