Gastromyzon farragus, H. H. Tan & C. U. M. Leh, 2006

H. H. Tan & C. U. M. Leh, 2006, Three new species of Gastromyzon (Teleostei: Balitoridae) from southern Sarawak., Zootaxa 1126, pp. 1-19 : 15-18

Gastromyzon farragus , new species

Figs. 5-6

Material examined: BORNEO: SARAWAK (Sadong River basin):

HOLOTYPE: SM uncatalogued, 30.9 mm SL; Serian, Sungai Kuhas, 6.9 km after Tebelu Tebakang turnoff, 5.8 km inside right side road (01º0910.0”N 110º2922.7”E); H. H Tan et al., 5 Sept. 1995.

PARATYPES: SM uncatalogued, 6 ex., 17.3-22.8 mm SL ; ZRC 47108, 7 ex., paratypes, 15.4-35.9 mm SL; collected with holotype . The following paratypic lots are also from the type locality, but with different collectors and dates of collection, as indicated. ZRC 47109, 6 ex., 15.3-36.1 mm SL; H. H Tan et al., 14 Jan. 1996 . ZRC 47110, 6 ex., 24.0-37.1 mm SL; H. H. Tan et al., 19 Feb. 1997 . ZRC 47111, 36 ex., 18.7-38.5 mm SL; Honours 98/99 Fish Group, 23 June 1998 .

NON-TYPE MATERIAL: ZRC 47120, 4 ex., 18.4-28.9 mm SL; Sarawak: Tebedu, Sungai Ahi, on road towards Mongkos (00º55.44'N 110º32.34'E); H. H. Tan et al., 12 June 1999 . The following non-type lots are all from the type locality, but with different collectors and dates of collection, as indicated. ZRC 47123, 5 ex., 24.9-32.0 mm SL; H. H Tan et al., 14 Jan. 1996 . ZRC 41212, 9 ex., 19.9-37.9 mm SL; H. H Tan et al., 19 Feb. 1997 . ZRC 47112, 12 ex., 13.6-37.0 mm SL; H. H. Tan et al., 29 Oct. 1997 . ZRC 47113, 9 ex., 28.8-38.8 mm SL (site 1, sample 1) ; ZRC 47114, 16 ex., 14.5-35.0 mm SL (site 1, sample 2) ; ZRC 47115, 64 ex., 13.3-37.1 mm SL (site 1, sample 3); Honours 98/99 Fish Group, 24 June 1998 . ZRC 47116, 31 ex., 11.0-37.6 mm SL (site 2, sample2) ; ZRC 47117, 30 ex., 20.8-37.8 mm SL (site 2, sample 3); Honours 98/99 Fish Group, 25 June 1998 . ZRC 47118, 10 ex., 14.7-33.2 mm SL (site 3, sample 2); Honours 98/99 Fish Group, 26 June 1998 . ZRC 43621, 20 ex., 10.3-38.2 mm SL; H. H Tan & W. K. Goh, 6 Feb. 1999 . ZRC 47119, 76 ex., 16.1-40.2 mm SL; H. H. Tan et al., 10 June 1999 . ZRC 47189, 10 ex., 24.4-39.5 mm SL; native collectors, 22 June 2002 .

Diagnosis.- Gastromyzon farragus differs from its congeners in having the following unique combination of characters: body dark brown, dorsum with 9-10 thin cream bars, side with spots and blotches, head dorsum dark brown with fine cream spots; caudal fin red in life; sublacrymal groove just visible when viewed from side; absence of a secondary rostrum; absence of a postoral pouch; gill slit angular, subopercular groove present and continuous to pectoral fin origin; a rounded snout when viewed dorsally; abdomen without scales; 52-55 scales in lateral line; pelvic fin not overlapping anal fin origin, adpressed dorsal fin not overlapping anal fin origin. Maximum size: 40.2 mm SL (ZRC 47119).

Description.-General body shape and appearance as in Figs. 5-6. Meristic and morphometric data appear in Table 1. Head rounded in dorsal profile, relatively short (26.7-28.3 % SL) and wide (20.1-21.8 % SL, 73.0-80.4 % HL), head relatively flattened (head depth 13.1-14.3 % SL, 49.0-51.1 % HL); snout elongated (snout length 57.5-61.8 % HL), tubercles present over entire head, concentrated on anterior part of snout; sublacrymal groove present, just visible from side of snout; gill slit strongly angular, subopercular groove pronounced and continuous to origin of pectoral fin base; postoral pouch absent; belly scales absent; posterior part of pectoral fin overlapping anterior part of pelvic fin; anteriormost pectoral and pelvic-fin rays with dorsal serrae; dorsal fin situated about mid body (predorsal length 56.0-58.6 % SL), adpressed dorsal fin not overlapping level of anal fin origin; deepest part of body at dorsal fin origin (body depth at dorsal fin origin 19.2-20.2 % SL); anus situated just beyond posterior base of fused pelvic fins; caudal peduncle relatively deep (10.3-11.5 % SL) and relatively long (9.3-11.1 % SL).

Pigmentation and life coloration. See Fig. 5. Body dark brown; dorsum with 9-10 thin cream bars; side with fine cream spots; ventrum cream; a tiny gold spot on posterior edge of every body scale. Head dorsum dark brown, with fine cream spots. Eye with golden iris. Dorsal fin yellowish brown, with 2 black bars, subdistal bar most distinct, hyaline interradial membrane and margin, antero-basal black spot present. Caudal-fin base yellowish, fin light brown with 1 subdistal thick black bar suffused with red, hyaline interradial membrane and yellowish margin. Anal-fin base black, fin light brown with 2 thin black bars, and hyaline margin. Pectoral and pelvic fins dark brown, with 2-3 rows of cream spots, and hyaline margins. Pelvic axillary flap brown with 5-6 cream spots.

Color in alcohol.-See Fig. 6. Body dark brown or black; dorsum with 9-10 faint thin cream bars; side with indistinct cream spots; ventrum cream. Head dorsum dark brown, with fine cream spots. Dorsal fin cream, with 2 black bars, subdistal bar most distinct, hyaline interradial membrane and margin, antero-basal black spot present. Caudal fin base cream, fin cream with 1 subdistal thick black bar, hyaline interradial membrane and margin. Anal-fin base black, fin cream with 2 thin black bars, hyaline margin. Pectoral fin dark brown with 2-3 broad rows of cream spots, hyaline margin. Suprapelvic posterior part over pelvic fin base flap light brown. Pelvic fin cream, with dark brown base, and thick hyaline margin. Juveniles with interrupted cream bars on posterior half of grey body; dorsum uniform; caudal fin base with 1 black bar.

Remarks.- Gastromyzon farragus can be further differentiated from G. ocellatus by having the head dorsum with fine cream spots only (vs. cream spots and blotches); anterior half of body with spots (vs. bars); 4-5 cream bars anterior to dorsal fin origin (vs. 3 bars); sublacrymal groove just visible from side (vs. not visible); fewer lateral-line scales (52-55, vs. 56-61); narrower head width (20.1-21.8, vs. 23.3-27.2 % SL; 73.0-80.4, vs. 90.0-95.9 % HL).

Distribution.- Gastromyzon farragus is currently only known from hill streams of the Sadong River basin in southern Sarawak (Fig. 7).

Etymology.-The species name is from the Latin farrago, meaning mixture. This is in allusion to the presence of both bars (on the dorsum) and spots (on the lateral) on body. Used as an adjective.