Revision of the Genus Henicorhynchus, with a Revised Diagnosis of Gymnostomus (Cyprinidae: Labeoninae) Author Ciccotto, Patrick J. Author Page, Lawrence M. text Copeia 2020 2020-08-06 108 3 485 502 http://dx.doi.org/10.1643/ci-19-304 journal article 10.1643/ci-19-304 2766-1520 13628562 Henicorhynchus caudimaculatus ( Fowler, 1934 ) Striped Mud Carp Figure 4 Tylognathus caudimaculatus Fowler, 1934:133 , figs. 89–90. Type locality: Thailand , Chiang Mai . Holotype : ANSP 58332 . Cirrhinus lineatus Smith, 1945:163 , fig. 25. Type locality: Thailand , Lam Ton Lang , a tributary of Menam Sak. Holotype : USNM 107960 . Cirrhinus caudimaculatus — Roberts, 1997 . FIG. 5. Henicorhynchus entmema . (A) ANSP 59092, holotype, 46.4 mm SL, (B) USNM 119490, holotype of H. lobatus , 96.7 mm SL. Images not to scale. Photo A by K. Luckenbill (ANSP); photo B by S. Raredon (USNM). Cirrhinus lineatus — Roberts, 1997 . Gymnostomus caudimaculatus — Kottelat, 2013 . Gymnostomus lineatus — Kottelat, 2013 . Diagnosis.— A member of Henicorhynchus distinguished from other members of the genus ( Table 1 ) by the following combination of characters: mouth subterminal, weakly oblique to nearly horizontal (less than or equal to 208 to midline of body); maxillary barbels present; edge of rostral cap straight, without medial indent; longitudinal stripes on flanks in most specimens, particularly larger individuals; FIG. 6. Henicorhynchus ornatipinnis , CAS 91756, holotype , 69.4 mm SL. Photo by J. Fong ( CAS ) . Downloaded From: https://bioone.org/journals/Copeia on 05 Aug 2024 Terms of Use: https://bioone.org/terms-of-use FIG. 7. Henicorhynchus siamensis , ANSP 68069, holotype of Cirrhinus marginipinnis , 113.7 mm SL. Photo by K. Luckenbill (ANSP). = caudal peduncle with small brown spot at medial insertion of opercula occasionally silver. Dorsal 1 to of flank light to 3 caudal fin in smaller specimens; caudal fin mostly clear, with dark brown, with scattered darker = brown spots on scales in scattered melanophores; pectoral, pelvic, and anal fins some specimens; ventral to 2 cream, yellow, or light 3 hyaline in life. brown. Brown to black spot on medial portion of caudal peduncle near caudal-fin insertion in smaller specimens Comparisons.— Henicorhynchus caudimaculatus is most similar (,100 mm SL). Up to seven brown longitudinal stripes on to H. entmema in having a subterminal mouth and maxillary flanks in most specimens; usually distinct in specimens barbels, but differs in having a straight edge on the rostral cap greater than approximately 40 mm SL. Venter cream, yellow, (vs. a medial indent on the rostral cap of H. entmema ) and in or light brown. Dorsal fin with dark brown clusters of usually having a series of longitudinal stripes along the flank melanophores forming blotches in middle portions of (vs. flank always immaculate in H. entmema ). interradial membranes, distal edge brown; pectoral, pelvic, and anal fins hyaline; caudal fin generally clear, with Description.— Morphometrics and meristics in Table 2. Mouth scattered melanophores. subterminal, weakly oblique to nearly horizontal. Maxillary barbels present. Edge of rostral cap straight, without medial Remarks.— In the original description of H. caudimaculatus , indent; rostral cap occasionally with well-developed tuber- Fowler (1934) noted a ‘‘grayish axial streak’’ along the flank of cles. Pectoral fin with 14–16 branched rays. Lateral-line scales the holotype (p. 126, fig. 90) in addition to a brown spot on and pored scales on caudal fin 31–34 þ 2–3; predorsal scales 9– the caudal peduncle near the insertion of the caudal-fin rays. 11; scale rows above lateral line 5; scale rows below lateral In similarly sized specimens previously identified as H. lineatus , line 4 –5; scale rows between lateral line and pelvic-fin a similar spot on the caudal peduncle is present and the lateral origin 4. Maximum length ¼ 150 mm SL ( Kottelat, 2001 ). stripes vary from very faint to bold (also noted by Roberts Dorsum of head and body brown. Dorsal of side of head [1997]), with some small specimens also possessing one light to dark brown; ventral ł cream to yellow; cheeks and distinct stripe. The types of Tylognathus caudimaculatus and FIG. 8. Henicorhynchus siamensis , UF 191421, live, 51.5 mm SL. Photo by Z. Randall (FLMNH). FIG. 9. Distributions of georeferenced specimens examined of: (A) Henicorhynchus caudiguttatus and H. ornatipinnis , (B) H. caudimaculatus , (C) H. entmema , and (D) H. siamensis . Cirrhinus lineatus Smith, 1945 share similar oromandibular morphology, specifically a subterminal, weakly oblique mouth, maxillary barbels, and a smooth rostral cap without a medial indent. Based on similarities in oromandibular structures and color patterns when comparing specimens of variable sizes, we recognize Cirrhinus lineatus as a junior synonym of H. Downloaded From: https://bioone.org/journals/Copeia on 05 Aug 2024 Terms of Use: https://bioone.org/terms-of-use caudimaculatus . There is ontogenetic variation in color pattern, with small individuals possessing a brown to black spot at the base of the caudal peduncle, with longitudinal stripes developing with age and the spot eventually disappearing. A similar pattern is observed in Lobocheilos rhabdoura ( Fowler, 1934 ) ( Ciccotto and Page, 2016a ) . Ciccotto and Page—Revision of Henicorhynchus Distribution.— Henicorhynchus caudimaculatus is distributed in the Chao Phraya basin in Thailand and the Mekong basin in Cambodia , Lao PDR, and Thailand ( Fig. 9B ). Material examined.— (Identified, but not measured if no SL given). Cambodia : Mekong basin: CAS 81552 , 5 , O Champha , 4–8 km upstream from its mouth into Tonle San (near Te Veng , Ratanakiri prov. ), 14.10068N , 107.13528E , 14 February 1994 ; CAS 91763 , 4 , 39.8–49.2 mm SL, Se Khone at Stung Treng , 13.51678N , 105.96678E , 6 February 1994 ; CAS 91765 , 1, 100.1 mm SL, Rotanah Kiri , O Changni , small stream on road from Ann Long Mea to Bang Lung , 13.73948N , 106.98738E , 12 February 1994 ; UMMZ 234464 , 2 , Kandal , Mekong River at northern tip of island upstream from Phnom Penh , 25 January 1996 ; UMMZ 234727 , 1 , Kandal , Prek Muk Kandal , across Tonle Sap from Phnom Penh , 1 March 1996 . Lao PDR: Mekong basin : CAS 92453 , 2 , 76.8– 104.5 mm SL, Attapu , Houay Samong, about 1 km upstream from its mouth into Xe Pian near Ban Hin Lat , 18.41558N , 103.60088E , 10 April 1995 ; CAS 92480 , 10 , Sekong watershed , small mountain stream entering right side of Se Kaman just upstream from Se Kaman , 14 April 1995 ; CAS 94791 , 8 , Mekong River , at Bang Hang Khone , just below Khone Falls , 13.96758N , 105.92988E , June 1993 ; CAS 96192 , 3 , Nam Hinboun watershed ; UMMZ 235345 , 1 , Champasak , Mekong River at Ban Hang Khone , just downstream from Khone Falls , 13.93338N , 105.93338E ; UMMZ 238636 , 1 , Vientiane , Nam Ngao at south end of Nam Ngum Reservoir , 18.56488N , 102.63888E , 5 February 1997 ; UMMZ 238669 , 1 , same as UMMZ 238636 ; UMMZ 240585 , 6 , Bokeo Province , Mekong River , 5 km upstream from Houay Xai , 20.13338N , 100.38338E , 25 April 1997 ; UMMZ 241035 , 1 , Bokeo , Mekong River , 9 km upstream from Houay Xai , 20.36678N , 100.36678E , 22 April 1997 ; UMMZ 241136 , 2 , Bokeo , Nam Tin at Ban Paktin , Nam Tin , 20.18338N , 100.558E , 26 April 1997 ; UMMZ 241148 , 3 , Bokeo , Nam Ngam at Ban Namngion , 20.38338N , 100.36678E , 24 April 1997 . Thailand : Chao Phraya basin : ANSP 58332 , holotype of Tylognathus caudimaculatus , 41.4 mm SL, Chieng Mai , North Siam , 720 km N of Bangkok , 19.21128N , 98.97088E , 1 January 1933 ; ANSP 58333 , 1 , 26.8 mm , same as ANSP 58332 ; CAS 91781 , 1 , 53.3 mm SL, Menam Wang , 79 km by road north of Lampang and 6 km east of highway 1035, 18.93218N , 99.64958E , 28 February 1991 ; UMMZ 236742 , 19 , Ping River below Blaumipol Dam at guesthouse, 17.24068N , 98.98158E , 8 May 1965 ; UMMZ 236915 , 1 , Bung Borapet , tributary to Nau River , 4 km N. Nakhon Sawan , 15.70918N , 100.13548E , 11 November 1964 . Mekong basin: CAS 79169 , 5 , mouth of Huay Ngao where it flows into Mekong , 1 km south of Ban Chaem Pong (ca. 30 km southeast of Chiang Khong ), 20.1428N , 100.52698E , 12 May 1990 ; CAS 91764 , 5 (of 7), 48.6–59.8 mm SL, Menam Kok at Tha Ton and up to 5 km downstream, 20.0498N , 99.38468E , 15 May 1990 ; CAS 91766 , 9 , Mekong mainstream between Pak Ing and Jom Paeng (about 4–5 km downstream), 20.17438N , 100.49018E , 16 January 1989 ; CAS 92855 , 1 , 77.7 mm SL, Mekong River mainstream, 14 km south of That Phanom , 16.82748N , 104.74998E , 6 April 1991 ; CAS 96196 , 1 , same as CAS 91766 ; UMMZ 251889 , 1 , Pong Need , trib. Pong River , 16.758N , 102.58E ; USNM 107960 , holotype of Cirrhinus lineatus , 108.8 mm SL, Lam Tong Lang , north of Pakjong , 14.748N , 101.30448E , 19 July 1925 ; USNM 119484 , 1 , 94.7 mm SL, Mefang , tributary of Mekok , 12 July 1936 . Downloaded From: https://bioone.org/journals/Copeia on 05 Aug 2024 Terms of Use: https://bioone.org/terms-of-use 493