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 caudiguttatus ( Fowler, 1934 ) Spotted Mud Carp Figure 3 Crossocheilus caudiguttatus Fowler, 1934:137 , fig. 103. Type locality: Thailand , Chieng Mai. Holotype : ANSP 58452 . Diagnosis.— A member of Henicorhynchus distinguished from other members of the genus ( Table 1 ) by the following combination of characters: mouth terminal, strongly oblique (35–458 to midline of body); maxillary barbels present; edge of rostral cap straight, without medial indent; flank immaculate, without longitudinal stripes; caudal peduncle with small brown spot at medial insertion of caudal fin; caudal fin with scattered brown spots in larger specimen ( holotype , 59.8 mm SL). Table 1. Characteristics that distinguish species of Henicorhynchus .

H. caudiguttatus	H. caudimaculatus	H. entmema	H. ornatipinnis		H. siamensis
Mouth position	Terminal, strongly	Subterminal, weakly	Subterminal, weakly	Subterminal, weakly		Terminal, strongly
oblique	oblique	oblique	oblique	oblique
Maxillary barbels	Present	Present	Usually present	Absent	Absent
Medial indent on rostral cap	Absent	Absent	Present	Absent	Absent
Flank patterning	Immaculate	Longitudinal stripes	Immaculate	Immaculate	Immaculate
or immaculate
Spot on caudal peduncle	Present	Present or absent	Present or absent	Absent	Absent
Caudal-fin patterning	Distinct brown	Mostly hyaline, with	Mostly hyaline, with	Anterior ł dusky,		Mostly hyaline,
spots or	scattered	scattered	posterior	hyaline	with scattered
hyaline	melanophores	melanophores	melanophores
Coloration of ventral fins	Hyaline	Hyaline	Hyaline	Red/orange	Hyaline

Comparisons.— Henicorhynchus caudiguttatus is distinguished from all other species of Henicorhynchus by the presence of brown spots on the caudal fin in larger specimens. Henicorhynchus caudiguttatus is further differentiated from all other species of Henicorhynchus except for H. siamensis by the presence of a terminal, strongly oblique mouth. Unlike H. siamensis , H. caudiguttatus possesses maxillary barbels. Description.— Morphometrics and meristics in Table 2. Mouth terminal, strongly oblique. Maxillary barbels present. Edge of rostral cap straight, without medial indent. Pectoral fin with 15 branched rays. Lateral-line scales and pored scales on caudal fin 32 þ 2; predorsal scales 8–10; scale rows above lateral line 5; scale rows below lateral line 4 –5; scale rows between lateral line and pelvic-fin origin 4. Maximum length ¼ 59.8 mm SL. Dorsum of head and body brown. Dorsal of side of head light brown; ventral = ł cream to yellow; cheeks and opercula silver. Dorsal 1 3 of flank = brown, with scattered darker brown spots on scales; ventral 2 3 silver. Faint brown spot on medial portion of caudal peduncle near caudal-fin insertion in holotype . Venter cream to yellow; breast silver. Dorsal fin with dark brown clusters of melanophores forming blotches FIG. 4. Henicorhynchus caudimaculatus . (A) ANSP 58332, holotype, 41.4 mm SL, (B) USNM 107960, holotype of Cirrhinus lineatus , 108.8 mm SL. Images not to scale. Photo A by K. Luckenbill (ANSP); photo B by S. Raredon (USNM). Ciccotto and Page—Revision of Henicorhynchus 489 in middle portions of interradial membranes, distal edge brown; pectoral, pelvic, and anal fins hyaline; caudal fin with scattered brown spots in holotype , hyaline in other specimens . Table 2. Morphometric and meristic values of Henicorhynchus caudiguttatus , H. caudimaculatus , H. entmema , H. ornatipinnis , and H. siamensis .

H. caudiguttatus		H. caudimaculatus		H. entmema		H. ornatipinnis		H. siamensis
( n ¼ 3)		( n ¼ 18)		( n ¼ 24)		( n ¼ 14)		( n ¼ 29)
Mean	Range	Mean	Range	Mean	Range	Mean	Range	Mean	Range
MORPHOMETRICS
Standard length (mm)	41.4	30.3–59.4	63.1	26.8–108.8	79.3	46.4–109.8	75.2	53.9–93.2	83.8	32.4–142.3
% Standard length
Predorsal length	50.0	48.5–50.9	49.1	45.5–51.1	49.1	47.2–50.9	48.3	46.5–50.7	48.9	46.1–51.8
Preanal length	75.9	72.0–78.4	77.7	76.4–80.3	77.7	74.6–80.2	78.3	75.4–82.3	76.9	74.0–80.4
Prepelvic length	52.5	50.6–55.1	53.5	50.9–57.2	53.4	50.7–55.9	51.7	49.1–53.7	52.2	48.8–57.4
Head length	26.3	24.2–28.2	26.0	22.5–29.6	24.8	22.6–27.9	21.7	20.1–23.0	28.1	25.5–32.1
Body depth at dorsal fin	24.1	23.5–24.6	27.4	24.0–29.7	28.6	21.4–35.2	28.3	26.4–30.1	29.9	25.2–34.4
Caudal-peduncle depth	11.5	10.8–12.0	12.4	11.4–13.1	12.1	11.2–13.2	14.6	14.1–15.3	12.7	11.7–13.9
Caudal-peduncle length	13.6	11.9–14.7	14.8	12.1–18.1	15.0	12.8–16.6	15.4	13.8–16.8	15.4	13.1–17.6
Dorsal-fin base length	14.5	13.3–16.2	15.3	13.3–17.8	15.5	13.9–17.6	15.1	12.5–16.8	16.1	14.1–17.5
Anal-fin base length	7.4	6.6–8.0	7.7	6.1–8.3	7.7	6.5–9.0	7.6	6.5–8.6	8.0	6.8–9.2
Pelvic-fin length	17.8	17.1–18.3	17.9	16.1–18.7	18.2	16.4–19.5	18.8	16.8–20.6	19.6	17.2–21.6
Pectoral-fin length	21.2	20.3–22.1	21.3	20.1–22.3	21.5	19.5–23.2	21.1	19.7–22.9	22.1	20.2–24.5
% Head length
Head depth	73.9	72.0–77.8	74.0	69.3–85.7	74.9	69.0–80.7	85.9	81.1–91.7	75.9	69.8–84.9
Head width	51.9	49.1–53.5	55.9	47.4–66.1	59.8	54.1–67.2	62.3	59.1–67.3	58.3	50.1–67.6
Snout length	28.5	27.6–29.0	32.3	27.0–37.1	34.4	30.6–38.9	30.4	25.3–32.7	30.8	25.1–35.8
Orbit diameter	28.0	26.1–30.3	25.1	19.5–30.1	24.5	21.2–29.6	29.3	27.5–33.3	25.1	19.1–33.8
Interorbital width	36.4	35.0–38.6	38.6	29.7–46.5	42.9	37.4–48.4	45.0	42.1–48.2	44.5	37.0–54.0
Mouth width	26.1	25.9–26.3	27.7	23.4–32.3	26.5	23.7–30.8	28.3	25.7–32.6	27.2	24.9–30.8
Postorbital length	44.6	42.3–46.6	43.5	39.3–48.4	40.8	35.0–47.1	41.1	36.6–45.1	45.2	38.4–49.6
Internarial width	22.8	21.7–23.5	20.6	17.0–24.4	21.9	15.8–27.0	21.1	18.4–25.7	21.5	18.1–25.0
Mode	Range	Mode	Range	Mode	Range	Mode	Range	Mode	Range
MERISTICS
Pectoral-fin rays	15	15	14	14–16	15	14–16	14	13–14	15	14–16
Lateral-line scales	32	32	33	31–34	34	31–35	34	33–35	34	33–35
Pored scales posterior to lateral line	2	2	3	2–3	2	1–3	3	2–3	3	2–4
Predorsal scales	8,9,10	8–10	10	9–11	10	9–11	10	10–12	10	9–11
Scales between dorsal-fin origin	5	5	5	5	5	5	5	5	5	5 –6
and lateral line
Scales between anal-fin origin	4	4 –5	5	4 –5	5	5 –6	5	5	5	5
and lateral line
Scales between pelvic-fin origin	4	4	4	4	4	4 –5	4	4	4	4
and lateral line

Remarks.— Roberts (1997) recognized H. caudiguttatus as a junior synonym of H. caudimaculatus ( Fowler, 1934 ) , noting that only the spotted caudal fin of the holotype of H. caudiguttatus differentiated this specimen from the type of H. caudimaculatus . No other specimen of Henicorhynchus examined here possesses similar spots on the caudal fin. The mouth positions of the type specimens of these two species also vary, with H. caudiguttatus possessing a terminal, strongly oblique mouth vs. a subterminal, weakly oblique (less than 208 to midline of body) to nearly horizontal mouth in H. caudimaculatus . Based on differences in mouth position and caudal-fin coloration, we recognize H. caudiguttatus as a valid species. This species has only been collected once, despite more recent collections throughout Chiang Mai province . Downloaded From: https://bioone.org/journals/Copeia on 05 Aug 2024 Terms of Use: https://bioone.org/terms-of-use Distribution.— Henicorhynchus caudiguttatus is known only from the type locality of Chiang Mai in northern Thailand ( Fig. 9A ). Material examined.— Thailand : Chao Phraya basin: ANSP 58452 , 1 , 59.8 mm SL, Chieng Mai, on Me Nam Ping, North Siam , 5 February 1933 ; ANSP 59089 , 2 (of 3), 30.3–34.0 mm SL, same as ANSP 58452 .