Bagarius dolichonema Zeng & Chen, 2025

Zeng, Yu-Yang, Pu, Xin-Rui, Lei, Hao-Tian, Oo, Thaung Naing & Chen, Xiao-Yong, 2025, A taxonomic review of Bagarius catfish (Siluriformes, Sisoridae) in the Salween and Irrawaddy rivers, with descriptions of two new species from China and Myanmar, Zoosystematics and Evolution 101 (3), pp. 1123-1136 : 1123-1136

Bagarius dolichonema Zeng & Chen sp. nov.

Figs 4 , 5 , Table 2

Bagarius sp. ‘Irrawaddy’ Ng & Kottelat, 2021: 141 (Irrawaddy River).

Type material.

Holotype. • KIZ 2024010545 , 216.6 mm SL, Min Sin , Downstream of Nam E Zu, a tributary of the Chindwin River, Sagaing Province, Myanmar, 25°31'20.7"N, 95°29'44.2"E, leg. Tao Qin, Nay Htet Naing, May 2019.

Paratypes. • KIZ 2024010547 , S 20191939 -1940, 3 ex, 135.5–177 mm SL, fish market of Hta Man Thi village , Chindwin River, Sagaing Province, Myanmar, 25°20'01.8"N, 95°17'12.4"E, leg. Tao Qin, Nay Htet Naing, Lamin Koko, December 2019 ; • KIZ 2024010543 , 1 ex, 251.3 mm SL, Kalaywa market , Chindwin River, Sagaing Province, Myanmar, 23°11'47.3"N, 94°17'49.8"E, leg. Paing Zaw, Nay Htet Naing, March 2018 ; S 20180428 , • KIZ 2024010544 , 2 ex, 150.6–226.5 mm SL, Hkamti market , Chindwin River, Sagaing Province, Myanmar, 26°00'06.4"N, 95°41'32.4"E, leg. Paing Zaw, Nay Htet Naing, May 2018 ; • KIZ 2024010542 , CXY 20170154 , 2 ex, 193.9–198.3 mm SL, Fish market of Pyay , Irrawaddy River, Bago Province, Myanmar, 18°50'06.1"N, 95°13'12.0"E, leg. Xiao-Yong Chen, Tao Qin, Shu-Sen Shu, Paing Zaw, Ye Yint Tun, Nay Htet Naing, June 2017 ; • KIZ 2024010546 , 1 ex, 128.7 mm SL, Stream of Nam Pagon , a tributary of the Chindwin River, Sagaing Province, Myanmar, 25°18'45.2"N, 95°31'40.9"E, leg. Tao Qin, Nay Htet Naing, Lamin Koko, December 2019 ; • KIZ 2007004082-083 , • KIZ 2007004088 , 3 ex, 206.4–252.7 mm SL, Kalay fish market , Myittha River, Sagaing Province, Myanmar, 23°10'53.1"N, 94°05'24.1"E, leg. De-Xin Feng, August 2007 .

Diagnosis.

Bagarius dolichonema can be distinguished from congeners by the following combination of characteristics: lateral margin of frontal straight, not forming brow ridge, dorsal spine strong (width 9.9–14.1 times its length), weakly notched antero-dorsal margin on pterygiophore of first dorsal-fin, filamentous extensions of pectoral-fin spine beyond posterior of pelvic-fin base and some reaching anus, neural spines of 4 th – 6 th vertebrae immediately anterior to adipose fin distally slightly flattened, adipose-fin origin at vertical through or very slightly posterior to anal-fin origin, caudal peduncle slender (3.8–4.6 % SL).

Description.

Head depressed; body subcylindrical, becoming more laterally compressed at caudal peduncle. Dorsal profile rising evenly from tip of snout to origin of dorsal fin, then sloping gently ventrally from origin of dorsal fin to end of caudal peduncle. Ventral profile straight to anal-fin base, then sloping gently dorsally from anal-fin base to end of caudal peduncle. Anus and urogenital openings located approximately 1 / 2 to 2 / 3 distance between base of last pelvic-fin ray and base of first anal-fin ray. Skin tuberculated, with tubercles of varying sizes on sides of body; larger tubercles arranged in longitudinal rows along dorsal head and dorsal lateral surfaces of body. Lateral line complete and situated mid-laterally. Vertebrae 21 + 20 = 41 * (4).

Head depressed and broad, triangular when viewed laterally. Snout prominent. Anterior and posterior nares adjacent, separated by base of nasal barbel. Gill opening broad, extending from ventral margin of post-temporal to isthmus. Dorsal surface of head covered by thick skin and ovoid tubercles. Eye small and ovoid; lateral margin of frontal not forming brow ridge. Base of supraoccipital spine wide, occipital bone triangular.

Barbels in four pairs. Maxillary barbel subtended by large skin flap along posterior edge of proximal half of barbel connected with side of snout; extending to middle of pectoral-fin base. Nasal barbel short, just extending to posterior margin of posterior nares. Outer mandibular barbel extending to vertical line through eye. Inner mandibular barbel about 2 / 3 of outer mandibular barbel in length.

Mouth inferior, most anterior part of premaxillary tooth band exposed when mouth closed. Oral teeth cone-shaped, varying in size, and irregularly aligned on all tooth-bearing surfaces. Premaxillary teeth form a broad semilunar band, interrupted at midline.

Dorsal fin located above anterior one-third of body, with I, 6 rays; dorsal spine straight and strong, smooth both on anterior and posterior margins, width 9.9–14.1 times its length. Adipose fin triangular, with anterior margin straight or slightly concave. Adipose fin origin at vertical through or very slightly posterior to anal-fin origin. Caudal fin rays i, 7, 7, i or i, 7, 8, i, strongly forked, with upper lobe longer than lower lobe and principal rays. Filamentous extensions with caudal fin extremely extending. Anal fin with straight anterior margin and concave posterior margin; with unbranched ray iii, branched ray 8, 9, or 10 rays. Pelvic-fin origin at vertical through posterior end of dorsal-fin base. Pelvic fin with slightly convex margin and i, 5 rays; tip of pelvic fin usually not reaching anal-fin origin, rarely reaching. Pectoral fin with I, 10, I, 11, I, 12, I, 13 rays; posterior margin slightly concave. Pectoral-fin spine with filamentous extension beyond anterior pelvic-fin base, or even reaching anus, smooth on anterior margin, serrated on posterior margin.

Coloration.

In 75 % ethanol: dorsal and ventral surfaces of head and body dark gray, ventral surface pale. Three dark brown saddles below dorsal fin, below adipose fin, and in posterior one-third of caudal peduncle. Dorsal fin dark gray with a medium brown band. Pectoral and pelvic fins dark gray. Anal fin gray with a dark patch close to its origin and a dark brown band in posterior part. Caudal fin gray, with dark patches at caudal-fin base, middle of upper and lower lobes. Head, body, and each fin with small dark spots, density of spots variable, absent in some individuals. Body more brown when alive.

Etymology.

The epithet name “ dolichonema ” comes from the Greek adjective “ dolikhos, ” meaning long, and the noun “ nēma, ” meaning thread or yarn, which refers to the length of filamentous extensions with pectoral-fin spines and caudal fins that are the longest in congeners except for B. bagarius . The suggested common name in Chinese is 长丝魾 (Pinyin: chang si pi).

Distribution.

Known to be found in the Irrawaddy River Basin in Myanmar (Figs 6 , 8 ) and the Manipur River in India, with its presence also expected in the Chinese part of the Irrawaddy River Basin.

Notes on habits.

B. dolichonema is also caught and sold as a food fish in Myanmar. In 2007, considerable quantities of B. dolichonema were sold on the Kalay fish market. In the stomachs of two specimens of B. dolichonema that were purchased, shrimp and crab pincers were found in one, and Glyptothorax nagpang with half-digested Cyprinidae fish was found in the other Fig. 7 . This reveals the broader diet of B. dolichonema , which is capable of feeding on prey in a variety of environments and swallowing parts of its body even when the prey is too large (e. g., crabs). B. dolichonema is still receptive to prey with sharp spines and swallows them into its stomach for digestion.

Figures

Figure 4. Lateral (A), dorsal (B), and ventral (C) views of Bagarius dolichonema sp. nov., KIZ 2024010545, holotype, 216.6 mm SL.

Figure 5. Fresh specimens of Bagarius dolichonema sp. nov., paratype, KIZ 2024010542, 193.9 mm SL, photo by Tao Qin.

Figure 6. Habitat of Bagarius dolichonema, Min Sin, Downstream of Nam E Zu, a tributary of the Chindwin River, Sagaing Province, Myanmar. Photo by Tao Qin.

Figure 7. Gastric contents of B. dolichonema from (A) KIZ 2007004088 and (B) KIZ 2007004083. Images not to scale.

Figure 8. Map showing collection localities of Bagarius protos and B. dolichonema.