Dzihunia pseudoamudarjensis, Sheraliev & Kayumova, 2024

Sheraliev, Bakhtiyor & Kayumova, Yorkinoy, 2024, Dzihunia pseudoamudarjensis, a new nemacheilid loach from the Syr Darya drainage (Teleostei: Nemacheilidae), Zootaxa 5536 (1), pp. 185-192 : 186-190

Dzihunia pseudoamudarjensis , new species urn:lsid:zoobank.org:act:69E8602C-3D46-453D-B0FB-7FA42E6F6A8E

( Figs. 2–4 )

Holotype. SWU 08122023001, 96 mm SL; Uzbekistan: Fergana Region : Great Fergana Canal at Ohunqaynar, about 3 km south of Kokand, 40.4871790, 70.9242720.

Paratypes. SWU 08122023002, 10, 61–107 mm SL; BSFC 0073 , 6 , 58–100 mm SL ; ZIN 57058 , 2 , 95–96 mm SL, same data as holotype .

Diagnosis. Dzihunia pseudoamudarjensis is distinguished from its congeners by a combination of characters and none of them unique to the species. It is distinguished from D. turdakovi ( Fig. 1 ) by possessing 84–86 lateral-line pores (vs. 100); a smaller dorsal fin depth 13.1–16.6% SL (vs. 17.7% SL) and a smaller anal fin depth 12.7–16.6% SL (vs. 16.9% SL), a deeper caudal peduncle 4.9–6.0% SL (vs. 4.4% SL), a wider interorbital distance 27.8–35.2% HL (vs. 24.5% HL), a shorter postorbital length 43.9–49.6% HL (vs. 51.3% HL), light-yellow abdominal area (vs. dark yellow), and a rounded snout (vs. pointed). The new species is distinguished from D. ilan ( Fig. 1 ) by having 11 infraorbital pores (vs. 9), 7 pores in the preoperculomandibular canal (vs. 5), a straight or slightly concave lower margin of the anal fin (vs. slightly convex), and lower number of vertebrae 43–44 vertebrae (vs. 46).

Dzihunia pseudoamudarjensis is distinguished from D. amudarjensis ( Fig. 1 ) by having a coarse vermiculate pattern of pale-yellowish lines on a dark-grey or brown background (vs. overall colorations plain brownish without pattern), often with a yellowish mid-lateral stripe on the caudal peduncle and the flank behind the vertical of the dorsal-fin origin (vs. absence), 84–86 lateral-line pores (vs. 90–95), caudal peduncle depth 3.5–4.5 times its length (vs. 4.8–6.0), and 43–44 vertebrae (vs. 45–47).

Description. General appearance shown in Figures 2–4 ; morphometric data provided in Table 1. Head long, body depth at dorsal fin origin 1.3–1.6 times in HL. Hump at nape absent. Head depressed, its maximum width greater than its depth. Snout blunt and rounded, its length similar to postorbital length. Body deepest and widest at midline between nape and dorsal-fin origin. Body depth decreasing from dorsal-fin origin to caudal-fin base. Body width greatest at posterior margin of pectoral fin. Predorsal profile slightly convex, prepelvic profile straight. Caudal peduncle slightly compressed, 3.5–4.5 times longer than deep. No pelvic axillary lobe or a very small, rudimentary lobe. Pelvic-fin origin below dorsal-fin origin. Pectoral fin reaching to approximately 51–75% of distance between pectoral- and pelvic-fin origins. Pelvic fin not reaching anus, not reaching vertical through tip of last dorsal-fin ray. Distance from anus to anal-fin origin 4.5–8.5 times in distance from pelvic-fin to anal-fin origins. Anal-fin origin behind vertical of adpressed dorsal-fin tip. Anal fin not reaching to caudal fin base. Adipose crest absents on caudal peduncle. Largest known specimen 107 mm SL.

Cephalic lateral-line system with 3 supratemporal, 7 supraorbital, 11 infraorbital, and 7 preoperculomandibular pores. Dorsal fin with 7½ branched rays, distal margin slightly concave. Anal fin with 5½ branched rays, distal margin straight or slightly concave. Pectoral fin with 9–10 (mode 10) and pelvic fin with 6 branched rays. Caudal fin forked with i,9+8,i rays, tip rounded and upper lobe longer than lower lobe in some individuals, equal in others. Body scaleless. Lateral line complete, with 84–86 pores. Anterior and posterior nostrils adjacent; anterior nostril as short tube with an elongated barbel-like tip; tip not reaching anterior margin of eye. Eye small. Mouth inferior, gape arched, rictus situated below the anterior nostril. Lips moderately thick, strongly furrowed, lower lip wide and medially interrupted ( Fig. 3 ). Upper and lower jaw covered by lips; processus dentiformis absent. Inner premaxillary barbel almost reaching base of maxillary barbel; outer premaxillary barbel long, usually not reaching to anterior edge of eye, rarely reaching; maxillary barbel moderately long, reaching posterior edge of pre-opercle.

Coloration. Body with a dark-brown background and yellowish or rarely whitish lines forming a coarse vermiculated pattern in both living and preserved individuals ( Fig. 4 ). A narrow yellowish, midlateral stripe behind vertical of dorsal-fin origin in some individuals. Yellowish lines dense or scattered. Dorsal surface of head and upper part of cheek with a vermiculated or marbled pattern. Ventral surface of head and lips yellowish or whitish without pattern. Snout usually dark- or pale-brown without pattern. Ventral surface of body yellowish without patterns or spots. Dorsal, pectoral and caudal fins with dark-brown rays. Several small, elongated blotches on first and second dorsal- and pectoral-fin rays. Anal and pelvic fins yellowish without blotches. Many individuals with dark brown blotches on base of pectoral and caudal fins.

Distribution. Dzihunia pseudoamudarjensis is known from the middle part ( Fig. 5 ) of the Great Fergana Canal in the Fergana Valley ( Uzbekistan District of the Fergana Region).

Etymology. The species is named pseudo - means “false” and amudarjensis because Turdakov (1948) thought that the population from the Fergana Valley was D. amudarjensis . An adjective.

Habitat. This species was found in slowly flowing, turbid water (in spring and summer) of the channel. They inhabit interspaces in the bottom substrate.

Remarks. Similar to other fishes inhabiting large rivers of the Aral Sea basin, species of the genus Dzihunia have lost large parts of their former habitats. Dzihunia amudarjensis was believed to be found in the Amu Darya and Syr Darya, but is restricted by this study to the Amu Darya. The currently IUCN conservation status of Dzihunia amudarjensis is Least Concern (LC) ( Karimov 2020a), however the restriction of the species to the Amu Dayra indicate a need for a re-assessment of its status. Moreover, action is needed to assess the conservation status of other Dzihunia species, including the new species herein described. Despite D. ilan being classified as LC by the IUCN ( Karimov, 2020b), our three surveys of the Zeravshan River failed to find the species ( Sheraliev & Peng, 2021). To improve our understanding of Dzihunia species conservation status, more detailed data on their distribution and threats are essential.

Figures

FIGURE 1. From top: D. ilan, ZIN 30501, holotype, 83 mm SL, Uzbekistan: Ak-Darya, a tributary of Zeravshan at Dagbit; D. turdakovi, ZIN 36723, holotype, 68 mm SL, Kyrgyzstan: from the ditch, Ters River (Talas River drainage); D. amudarjensis, ZIN 22042, syntype, 73 mm SL, Uzbekistan: Amu Darya near Termez.

FIGURE 2. Dzihunia pseudoamudarjensis, SWU08122023001, holotype, 96 mm SL; Uzbekistan: Great Fergana Canal.

FIGURE 3. Dzihunia pseudoamudarjensis, SWU 08122023002, paratype, 93 mm SL; Uzbekistan: Great Fergana Canal.

FIGURE 4. Dzihunia pseudoamudarjensis, Uzbekistan: Great Fergana Canal: from top: SWU 08122023002, 86 mm SL (paratype); BSFC 0073, 102 mm SL (paratype); not preserved, about 95 mm SL; SWU 08122023002, 93 mm SL (paratype).

FIGURE 5. Type locality of D. pseudoamudarjensis; Uzbekistan: middle part of the Great Fergana Canal at Kokand, photograph taken on 8 December 2023.