Eirmotus insignis, Kottelat, 2008

Kottelat, Tan Heok Hui Maurice, 2008, Revision Of The Cyprinid Fish Genus Eirmotus, With Description Of Three New Species From Sumatra And Borneo, Raffles Bulletin of Zoology 56 (2), pp. 423-433 : 430-432

Eirmotus insignis , new species

( Figs. 6a–b , 7d , 8b )

Eirmotus octozona (non Schultz, 1959): Roberts, 1989: 38, Fig. 23 (MZB 3121); Kottelat et al., 1993: 35 (part), Pl. 8 (CMK 6816).

Material examined. – MZB 3121 , holotype, 31.2 mm SL, Kalimantan Barat: several small forest streams flowing into Kapuas mainstream within 10 km upstream from Sanggau (0°06'07"N 110°35'38"E) , T. R. Roberts , 16–17 Jul.1976 ; MZB 3120 , 2 paratypes, 16.8–17.6 mm SL, Kalimantan Barat: Sungai Tekam, small forest stream joining right side of Kapuas mainstream ca. 2 km upstream from Sanggau (0°07.5'N 110°36'E) , T. R. Roberts , 16 Jul.1976 ; MZB 3122 , paratype, 18.8 mm SL, Kalimantan Barat: swampy stream ca. 30 km west of Sintang on road from Sanggau to Sintang (ca. 0°00'N 111°14'E) ; T. R. Roberts , 18 Jul.1976 ; MZB 3123 , paratype, 24.5 mm SL, Kalimantan Barat: forest stream ca. 1 km up Sungai Tajan from Tajan, 87 km east of Pontianak (0°02'S 110°07'E) , T. R. Roberts , 22 Aug.1976 ; CMK 10298 , 18 paratypes, 11.8–23.1 mm SL, Kalimantan Barat: Kapuas basin, several small tributaries of Sungai Embaluh Leboyan and Sungai Semalah ( Nanga Semalah : 0°52'16"N 112°17'37"E), M. Kottelat et al., 9 Sep.1993 ; ZRC 38786 , 3 paratypes, 19.3–23.2 mm SL , CMK 11573 , 4 paratypes, 12.9–22.9 mm SL, Kalimantan Barat: Kapuas basin, Sungai Letang near Kampung Kandung Suli (0°37'42"N 112°15'15"E), M. Kottelat et al., 8 Jun.1995 ; CMK 6816 , 1 paratype, 28.2 mm SL, Kalimantan Barat: Sungai Melawi basin: Sungai Taok at Terusan ( Kec. Dedai ), km 22 on road from Sintang to Putussibau : 0°02'55"N 111°42'12"E, M. Kottelat et al., 24 Apr.1990 .

Non-type material: ZRC 46315 , 35 ex., 16.3–29.5 mm SL, Kalimantan Barat: Pontianak, trade material, F. Yuwono, 1 Oct.1999 ; ZRC 46307 (tentative identification), 2 ex., 23.7–30.4 mm SL, Belitung Island ; T. Sim, Feb.2000 .

Diagnosis. – Eirmotus insignis is distinguished from all other species of Eirmotus by having the black pigmentation along the simple dorsal-fin rays restricted to the anterior two rays and the proximal half of the third one, fainter grey distally (vs. extending on entire length of rays); and a row of faint black spots at about 2/3 of the branched dorsal-fin rays (extending on the membranes in some specimens) ( Fig. 7d ). It is further distinguished by the following combination of characters: bar 1 present but faintly marked; serrae along posterior edge of last simple dorsal-fin ray 16–21; width of bar 5 equal to 1–1½ lateral row scales; a small and distinct black mark immediately in front of anus, visible in lateral view ( Fig. 7d ); head length 32.3–33.5 % SL, 47.4–50.0 % BL; predorsal length 76.4–78.8 % BL; interorbital width 22–25 % HL; snout slightly upturned, mouth terminal, lower jaw wide, anteriorly rounded ( Fig. 8b ).

Description. – See Fig. 6a–b for general body shape and Table 1 for meristics and morphometrics. Size up to 32.1 mm SL. Dorsal with 3 simple and 8½ branched rays; origin above lateral row scale 6–7. Anal fin with 3 simple and 5½ branched rays; origin under lateral row scale 11–12. Pelvic fin with 1 simple and 8 branched rays, origin under lateral row scale 4–5. Lateral row scales 19–21; predorsal scales 7; transverse scales ½7½ between dorsal-fin and anal-fin origins, ½3½ on caudal peduncle.

Snout slightly upturned, often with a marked angle at articulation of lower jaw. Mouth terminal, upper lip not entirely distinct in ventral view; lower jaw relatively wide, rounded anteriorly ( Fig. 8b ).

Colouration. – Preserved: Body yellowish-brown; markings dark grey to black. Bar 1 absent or very faintly marked. Bars 2 and 3 usually not reaching ventral midline. Bar 4 reaching or not ventral mid-line. A spot between bars 5 and 6, at posterior extremity of dorsal-fin base. Bar 5 usually not reaching pelvic-fin base and ventral midline. A spot on ventral midline immediately in front of anus, about halfway between bars 5 and 6. Axial streak distinct between bars 5 and 8. In some specimens, one dark spot on lateral midline between bars 5 and 6.

Fins hyaline. Dorsal fin with black pigmentation along simple rays restricted to anterior two rays and proximal half of third one, fainter grey distally; a row of faint black spots at about 2/3 of branched rays, sometimes extending on membranes; and a black mark at posterior tip of dorsal fin, adjacent to upper extremity of bar 6. Anterior rays of anal fin black at base, continuing bar 6. Base of pelvic-fin rays black.

In life, body yellowish, translucent, bars greyish to black.

Distribution. – Eirmotus insignis is currently known only from the Kapuas drainage in Kalimantan Barat (Borneo) and from Belitung Island.

Life history notes. – Eirmotus insignis was most frequently observed in small streams with slowly flowing water, backwaters, among overhanging roots along shores, occasionally in swampy areas among dense vegetation. The water was generally quite murky, slightly acid; the bottom was usually muddy or covered by leaf litter.

Etymology. – From the Latin insignis , meaning worth distinction, with distinctive signs, brilliant, referring to the unique black marks on the dorsal fin. An adjective.

Comparative notes. – See E. octozona , E. isthmus and E. furvus for characters distinguishing them from E. insignis .

Figures

Fig. 6. Eirmotus insignis: a, MZB 3121, holotype, 31.2 mm SL; b, ZRC 38786, paratype, 23.2 mm SL, Borneo: Kalimantan Barat, Kapuas.

Fig. 7. Flank of Eirmotus species, showing dorsal fin and pre-anus patterns in: a, E. octozona, ZRC 8385, 35.6 mm SL; b, E. isthmus, ZRC 50992, 32.0 mm SL; c, E. furvus, ZRC 39152, 27.3 mm SL; and d, E. insignis, ZRC 38786, 23.2 mm SL.

Fig. 8. Head of Eirmotus species, showing ventral view of snout and lower jaw of: a, E. isthmus, MZB 10720, 29.2 mm SL; and b, E. insignis, ZRC 38786, 23.2 mm SL.