Lobocheilos aurolineatus Ciccotto and Tan, 2018

Ciccotto, Patrick J. & Tan, Heok Hui, 2018, A new species of Lobocheilos (Teleostei: Cyprinidae) from East Kalimantan, Indonesian Borneo, Zootaxa 4399 (4), pp. 543-552 : 544-547

Lobocheilos aurolineatus Ciccotto and Tan , sp. n.

Figs. 1–2 , Table 1

? Tylognathus hispidus (non Valenciennes, in Cuvier & Valenciennes 1844): Vaillant 1902: 108; and Popta 1906: 108.? Lobocheilus hispidus (non Valenciennes, in Cuvier & Valenciennes 1844): Christensen 1992: 600.? Lobocheilos kajanensis (Popta 1904) : Kottelat 1995: 404.

Holotype. MZB 17222, 55.6 mm SL; Indonesia: Borneo: East Kalimantan: Mahakam River at Kota Bangum , 0°16.02’S 116°35.16’E; H.H. Tan & D. Wowor, 7–9 Nov 1999.

Paratypes. MZB 17223, 5, 52.9–59.1 mm SL; Indonesia: Borneo: East Kalimantan: Mahakam basin, Lake Jempang , 0°25.29’S 116°15.78’E; H.H. Tan and D. Wowor, 9 Nov 1999 ; UF 191478, 2, 55.7–58.7 mm SL, same data as MZB 17223 ; ZRC 54764, 4, 48.9–54.9 mm SL, same data as MZB 17222 ; ZRC 54765, 5, 53.2–59.9 mm SL, same data as MZB 17223.

Other material. ZRC 51577, 17, 39.8–55.6 mm SL; Indonesia: Borneo: East Kalimantan: Aquarium trade; ZRC 54745, 7, 36.3–42.5 mm SL; Indonesia: Borneo: East Kalimantan: Balikpapan, aquarium trade.

Diagnosis. A member of Lobocheilos as diagnosed by Kottelat & Tan (2008). Lobocheilos aurolineatus is differentiated from all other members of the genus except for L. ixocheilos Kottelat & Tan and L. tenura Kottelat & Tan in possessing a single, broad black midlateral stripe extending from the operculum to the caudal-fin base. Lobocheilos aurolineatus differs from L. ixocheilos and L. tenura in possessing a thin cream to yellow stripe on the anterior ¾ of the flank, separating the midlateral stripe from the brown dorso-lateral scales (vs. stripe absent in L. ixocheilos and L. tenura ; Fig. 3 ) and a small mouth width (23.5–29.9% HL in L. aurolineatus vs. 32.1–45.0% and 34.4–46.4% HL in L. ixocheilos and L. tenura , respectively).

Description. Morphometric and variable meristic data presented in Table 1. Dorsal profile of head and body continuous; body deepest at dorsal-fin origin. Ventral profile from tip of snout to anal fin slightly rounded. Snout conical. Head short, longer than wide. Eyes lateral. Dorsal-fin origin anterior of pelvic-fin origin. Pectoral fin pointed, positioned ventrally, reaching ¾ distance between pectoral-fin origin and pelvic-fin origin when adpressed. Pelvic fin pointed, concave, reaching anus when adpressed. Anal fin reaching ¼ distance to base of caudal fin when adpressed. Dorsal and anal fins slightly concave. Caudal fin deeply forked with pointed lobes, approximately equal in length. Axillary pelvic lobe well developed.

Mouth inferior. Rostral cap covering most of upper lip; smooth edge. Upper lip fused with upper jaw; continuous with lower lip around corner of mouth; edge smooth; small papillae present at corner connection with lower lip. Lower jaw straight; cornified at edge. Lateral and anterior portions of lower lip free, forming a distinct fleshy pad; posterior portion thinner and connected to upper lip; anterior edge with small papillae. Maxillary barbels present, shorter than eye diameter.

Dorsal-fin rays iii,8, posteriormost split to base; anal-fin rays iii,5, posteriormost split to base; pelvic-fin rays i,8; pectoral-fin rays i,14–16, mode 15; principal caudal-fin rays 10+9, branched caudal-fin rays 9+8. Body entirely scaled, scales large. Lateral-line scales and pored scales on caudal fin 31–32 + 2–3, mode 32 + 2; predorsal scales 10–11, mode 11; scale rows above lateral line 5½; scale rows below lateral line 4½; scale rows between pelvic-fin origin and lateral line 3½ (rarely 3); circumpeduncular scales 16.

Color in Preservative. See Figure 1 . Dorsum of head and body brown, dark brown blotch posterior to eyes on head, black midline from posterior of head to caudal peduncle, approximately ¼ scale height in thickness, scales with fine black spots around posterior edges. Dorsal half of side of head light to dark brown, ventral half cream to yellow; silver on cheek and ventral half of operculum. Broad, black midlateral stripe extending from operculum to insertion of caudal fin, not extending onto middle caudal-fin rays. Thin cream to yellow stripe above anterior ¾ of midlateral stripe posterior to operculum, separating black midlateral stripe from brown dorso-lateral scales. Dorsolateral scales brown centrally with yellowish margin, overlain with scattered dark brown flecks on posterior edges; scales below midlateral stripe cream to yellow. Venter cream to yellow with silver patch on breast and isthmus. Dorsal fin with scattered black speckling, more concentrated on medial portions of interradial membranes. Caudal fin with scattered black speckling, concentrated on distal portions of upper and lower lobes and occasionally on middle rays. Pectoral, pelvic, and anal fins hyaline. Smaller specimens notably more silvery on head and body.

Color in Life. See Figure 2 . Dorsum of head and body yellowish-brown, golden-brown patch posterior to eyes on head. Black stripe from tip of snout to anterior edge of mid-eye, continuous after eye to operculum edge; black midline from posterior of head to caudal peduncle continuous to middle of caudal-fin margin. Gold stripe above black midline, ending at caudal-fin base. Posterior lower half of black midline slightly edged with gold. Lower half and ventrum of body cream. All fins hyaline, except dorsal-fin with mid-row of black pigments on interradial membrane and caudal fin with scattered black speckling.

Remarks. The minimum polygon clusters formed by plotting the second and third sheared principal components of the morphometric data of L. aurolineatus , L. ixocheilos , and L. tenura are presented in Fig. 4 . Size accounted for 98.4% of the observed variance. The second sheared principal component accounted for 4.0% of the observed variance. Mouth width (0.63) and body depth (-0.53) had the highest loadings on the sheared second principal component. The third sheared principal component accounted for 3.5% of the observed variance, and mouth width (0.61) and the length of the anal-fin base (-0.55) had the highest loadings. The minimum polygon of L. aurolineatus does not overlap with the polygons of L. ixocheilos and L. tenura , indicating the former is distinct in body shape from the latter two species.

In the description of L. tenura, Kottelat & Tan (2008) tentatively noted that this species from the Kapuas basin in West Kalimantan, Indonesia was figured in Roberts (1989) as L. hispidus (Valenciennes, in Cuvier & Valenciennes) . We examined two specimens listed by Roberts (1989) as L. hispidus (USNM 230178, 53.7–66.5 mm SL). Both of these specimens possess a slender caudal-peduncle depth (10.7–10.9% SL) within the range listed by Kottelat & Tan (2008) in diagnosing L. tenura . Specimens of L. ixocheilos examined here possess a deeper caudal peduncle (11.2–12.9% SL) as well, although this range is somewhat below the range of 12.3–13.7% SL listed by Kottelat & Tan (2008) in the description of that species. Despite some overlap in the minimum polygon clusters ( Fig. 2 ), we tentatively identify these specimens as L. tenura based on differences in caudal-peduncle depth. Kottelat & Tan (2008) noted some variation in overall body depth among the types of L. tenura , with the holotype and one paratype (ZRC 51178) being more slender than the other type material. Here also the paratype is more slender than the other specimens examined ( Fig. 2 ).

Distribution. Lobocheilos aurolineatus occurs in the Mahakam River (up to Kampung Data Belang [00°13.968’N, 115°27.610’E]) and Lake Jempang, a seasonal floodplain of the river, in East Kalimantan, Indonesian Borneo ( Fig. 5 ).

Etymology. aurolineatus from the Latin aureus, gold, and lineatus, lined, in reference to the gold stripe along the flank in live specimens.

Figures

FIGURE 1. Dorsal, lateral, and ventral views of the holotype of Lobocheilos aurolineatus, MZB 17222, 55.6 mm SL.

FIGURE 2. Live specimens in captivity, not preserved. Specimen in foregroundca. 60 mm SL.

FIGURE 3. Lobocheilos ixocheilos, ZRC 51772, paratype, 280 mm SL (top) and L. tenura, ZRC 51178, paratype, 107.9 mm SL (bottom).

FIGURE 5. Distribution of Lobocheilos aurolineatus from eastern Borneo (inset). Star denotes the locality of the holotype.

FIGURE4. Plot of the sheared second (PC2) and third (PC3) principal componentsof Lobocheilos aurolineatus, L.ixocheilos, and L.tenura.