Pareuchiloglanis abbreviatus, Li, Xu, Zhou, Wei, Thomson, Alfred W., Zhang, Qing & Yang, Ying, 2007

Li, Xu, Zhou, Wei, Thomson, Alfred W., Zhang, Qing & Yang, Ying, 2007, A review of the genus Pareuchiloglanis (Sisoridae) from the Lancangjiang (upper Mekong River) with descriptions of two new species from Yunnan, China, Zootaxa 1440, pp. 1-19 : 2-7

Pareuchiloglanis abbreviatus sp. nov.

( Fig. 1 )

Holotype. SWFC 0 311021, 115.2 mm TL, 97.2 mm SL; Chuanghe (upper Lixianjiang, branch of Red River), Mona (22°27'54”N 100°46'79”E), Jingdong County, Yunnan Province, Q. Wang, 1 Nov. 2003.

Paratypes. SWFC 0 311022, 0 311024 (2; 78.0– 99.6 mm TL, 66.0– 85.2 mm SL), same data as holotype. SWFC 0 303248 (1; 125.8 mm TL, 112.2 mm SL), Xiaobahe (upper Weiyuanjiang, branch of the Lancangjiang), Donggualin (24° 18.43N 100° 46.61E), Zhenyuan County, Yunnan Province, W. Zhou & Q. Wang, 29 Sept. 2003.

Diagnosis. Characters distinguishing Pareuchiloglanis abbreviatus from P. gracilicaudata , P. kamengensis , P. myzostoma and P. prolixdorsalis are summarized in Table 1 . A species of Pareuchiloglanis with the following unique combination of characters: adipose-fin base not confluent with caudal fin (vs. confluent); premaxillary tooth patches appear joined (vs. separate); lower lip connected to base of maxillary barbel by skin flap, without sulcus between them (vs. not connected, with sulcus); 6 upper + 7 lower branched caudalfin rays (vs. 7+8); dorsal fin i-5 (vs. i-7); anal fin ii-3 (vs. ii-8); pelvic-fin origin to anal-fin origin distance shorter than pelvic-fin origin to mouth distance (vs. equal); pectoral fin extending beyond pelvic-fin origin (vs. not reaching); origin of pelvic fin anterior to end of dorsal-fin base (vs. opposite to or posterior to end of dorsal-fin base); anus nearer to posterior end of pelvic-fin base than anal-fin origin (vs. nearer to anal-fin origin); anal-fin origin nearer to posterior end of pelvic-fin base than to caudal-fin base (vs. nearer to caudal-fin base); short interdorsal, tip of dorsal-fin reaching origin of adipose fin when depressed (vs. not reaching); snout length 49.1–52.9% HL; predorsal length 26.1–27.8% SL; head length 25.7–28.0% SL; head width 26.8– 27.2% SL; caudal peduncle length 22.4–26.2% SL; and caudal peduncle depth 4.8–6.6% SL.

Pareuchiloglanis abbreviatus is distinguished from P. gongshanensis , P. feae , P. kamengensis and P. m a c - ropterus by the following characters: premaxillary tooth patches appear joined with median indentation (vs. separate) ( Fig. 2 A); lower lip connected to base of maxillary barbel by skin flap, without sulcus between them (vs. not connected, with sulcus) ( Fig. 3 A). It differs from P. gracilicaudata , P. longicauda , P. macrotrema , P. myzostoma , P. robusta and P. s i n e n s i s by its longer pectoral fin, pectoral fin extending beyond origin of pelvic fin (vs. not reaching), and differs from P. anteanalis , P. nebulifer and P. prolixdorsalis by tip of dorsal fin reaching origin of adipose fin when depressed (vs. not reaching). It differs from P. feae , P. poilanei , P. sichuanensis and P. tianquanensis by its adipose-fin base not being confluent with caudal fin (vs. confluent). Pareuchiloglanis abbreviatus differs from P. gracilicaudata , P. m y z o s t o m a, P. nebulifer and P. robusta by having 6+7 branched caudal-fin rays (vs. 7+8). It differs from P. songmaensis by having fewer fin rays, dorsal fin i-5, anal fin ii-3 (vs. i-7, ii-8) and differs from P. longicauda and P. s i n e n s i s by having origin of pelvic fin anterior to end of dorsal-fin base (vs. opposite to or posterior to end of dorsal-fin base). Pareuchiloglanis abbreviatus differs from P. songdaensis by having distance between pelvic-fin origin to anal-fin origin shorter than that to mouth (vs. equal), and longer head, head length 25.7–28.0% SL (vs. 21.5% SL). It differs from P. m a c - rotrema and P. rhabdurus by having origin of anal fin nearer to posterior end of pelvic-fin base (vs. nearer to caudal-fin base). It differs from P. rhabdurus by the following characters: shorter snout, 49.1–52.9% HL (vs. 57.0% HL), shorter predorsal length, 26.1–27.8% SL (vs. 34.6% SL), wider head, width 26.8–27.2% SL (vs. 20.1% SL), and longer caudal peduncle, 22.4–26.2% SL (vs. 17.6% SL). Pareuchiloglanis abbreviatus differs from P. sichuanensis and P. s i n e n s i s by narrower caudal peduncle, 4.8–6.6%SL (vs. 7.8–11.4% SL). It further differs from P. gongshanensis , P. kamengensis , P. macropterus and P. m y z o s t o m a by having the anus nearer the posterior end of the pelvic-fin base (vs. nearer anal-fin origin).

Description. Morphometric and meristic data are in Table 2 . Mouth wide, inferior, transverse. Anterior margin of premaxillary tooth patches exposed when mouth closed. Oral teeth coniform, embedded in skin, only tips exposed, irregular rows. Premaxillary tooth patches broad, appear joined, with median indentation, sides not extending backwards ( Fig. 2 A). Gill opening extending from posttemporal region to base of second pectoral-fin element. Post-labial groove interrupted, ending at base of inner mandibular barbel. Lower lip connected to base of maxillary barbel by skin flap, without sulcus between them ( Fig. 3 A).

Head compressed, rostral margin rounded when viewed dorsally. Head and abdominal region moderately broad. Dorsal profile rising gradually from tip of snout to origin of dorsal fin, then sloping slowly ventrally to end of caudal peduncle. Oral region, anterior part of abdomen with dense papillae; density gradually decreasing posteriorly. Eye small, almost round, subcutaneous, dorsal. Eye closer to tip of snout than to dorsalmost extremity of gill opening. Barbels flattened, in four pairs. Nasal barbel with small flap of thin skin fringing posterior margin, reaching anterior margin of orbital. Maxillary barbel with thin flap of skin fringing posterior margin, pointed tip, extending to or beyond origin of pectoral fin. Origin of inner mandibular barbel close to midline. Outer mandibular barbel originating posterolateral of inner mandibular barbel, reaching nearly to first pectoral-fin element.

Dorsal fin at point through anterior third of body; without spine, margin straight, tip of dorsal-fin rays extending beyond vertical through posterior end of pelvic-fin base, to origin of adipose fin when depressed. Adipose fin with long base, at least half of postdorsal distance; fin margin almost straight for entire length, adipose-fin base deeply incised posteriorly. Base of adipose fin shorter than predorsal length. Origin of anal fin anterior, distance to caudal-fin base longer than to origin of pelvic fin. Pectoral and pelvic fins enlarged, with broadly rounded margins, first element on each broadened, with regular striae on ventral surface. Pectoral fin extending beyond origin of pelvic fin. Pelvic fin extending beyond anus. Anus nearer to posterior end of pelvic-fin base than to anal-fin origin. Caudal fin truncate. Skin smooth. Lateral line complete and midlateral.

Colouration. Green-yellow on dorsal surface, milk-white on venter. Light yellow spot on posttemporal area. Pair of yellow spots on dorsal, adipose and caudal fins. Pectoral and pelvic fins green-yellow with lighter colour around distal edge. Dorsal fin green-yellow with lighter medial band and distal edge. Caudal fin grayblack with small yellow patch in middle.

Distribution. Known from the Lancangjiang [Mekong] and the Lixianjiang [Red River] drainages ( Fig. 4 ).

Etymology. From the Latin abbreviatus , meaning shortened, in reference to abdominal region shorter than other congeners. Used as an adjective.

Remark. There are no notable differences in counts and proportional measurements between specimens from the Lancangjiang [Mekong] and the Lixianjiang [Red River] ( Table 2 ).

continued.

Figures

FIGURE 1. Pareuchiloglanis abbreviatus, SWFC 0 311021, holotype, 97.2 mm SL; Mona, Jingdong county, Yunnan province, China. Dorsal, lateral and ventral views.

FIGURE 2. Ventral view of premaxillary tooth band. A, premaxillary tooth patches appear joined with a shallow median indentation (Pareuchiloglanis gracilicaudata, SWFC 0 0 0 4052, 110 mm SL); B, premaxillary tooth patches appear separate with a deep median indentation (Pareuchiloglanis kamengensis SWFC 0 411001, 149 mm SL); C, premaxillary tooth patches separate (Oreoglanis setiger, SWFC 0 411019, 94.4 mm SL).

FIGURE 3. Ventral view of maxillary barbel and lower lip. A, maxillary barbel and lower lip connected directly (Pareuchiloglanis gracilicaudata, SWFC 0 0 0 4052, 110 mm SL); B & C, maxillary barbel and the lower lip interrupted by an obvious sulcus (s) (B, Pareuchiloglanis kamengensis, SWFC 0 411001, 149 mm SL; C, Oreoglanis setiger, SWFC 0 411019, 94.4 mm SL).

FIGURE 4. Map showing distributions of species of Pareuchiloglanis in the Lancangjiang (upper Mekong River) and Honghe (Red River or Song Hong) drainages.

Tables

TABLE 1. Summary of main characters distinguishing Pareuchiloglanis abbreviatus, P. gracilicaudata, P. kamengensis, P. myzostoma and P. prolixdorsalis.

Character	P. abbreviatus	P. gracilicaudata	P. kamengensis	P. myzostoma	P. prolixdorsalis
Premaxillary tooth patches	Appear joined	Appear joined	Separate	Appear joined	Appear joined
Pelvic fin reaching anus	Yes; extending beyond anus	Yes	No	No	Yes
Branched caudal-fin rays	6+7	7+8	7+8	7+8	6+7
Distance between ori- gin of pelvic fin to origin of anal fin	Shorter than dis- tance to mouth	Shorter than dis- tance to mouth	Shorter than dis- tance to mouth	Shorter than dis- tance to mouth	Longer than dis- tance to mouth
Anus position	Nearer pelvic-fin base than anal- fin origin	Midway between anal-fin origin and pelvic-fin base	Nearer anal-fin origin than end of pelvic-fin base	Nearer anal-fin origin than pel- vic-fin base	Nearer pelvic-fin base than anal-fin origin
Origin of anal fin	Nearer pelvic-fin base than caudal- fin base	Midway between pelvic-fin base and caudal-fin base	Nearer caudal- fin base than pel- vic-fin base end	Nearer caudal- fin base than pel- vic-fin base end	Nearer caudal-fin base than pelvic-fin base end
Snout length (% HL)	49.1–52.9	58.3–81.3	46.7–62.5	47.2–52.0	50.9–64.3
Caudal peduncle length (% SL)	22.4–26.2	18.6–22.8	9.5–20.4	17.0–19.3	18.2–22.2
Caudal peduncle depth (% SL)	4.8–6.6	3.5–6.0	6.5–8.9	5.0–5.9	4.5-5.6

TABLE 2. Counts and proportional measurements of Pareuchiloglanis abbreviatus and P. kamengensis (italic and bold indicate a diagnostic difference between species).

	P. abbreviatus
Locality	Jingdong: Mona	Zhenyuan: Donggualin
Number of specimens	3	1
Dorsal-fin rays	i-5	i-5
Pelvic-fin rays	i-5	i-5
Pectoral-fin rays	i-13-15	i-17
Anal-fin rays	ii-3	ii-3
Branched caudal rays	6+7	6+7
in% standard length	mean range S.D.	range
Predorsal length	27.1 26.1–27.8 0.91	41.5
Length of dorsal-fin base	9.5 9.2–10.0 0.46	10.4
Body depth	13.2 12.5–14.1 0.79	12.0
Head length	27.2 25.73–28.0 1.28	27.7
Maximum head width	26.9 26.8–27.2 0.26	24.0
Caudal peduncle length	23.9 22.4–26.2 2.02	25.0
Caudal peduncle depth	5.6 4.8–6.6 0.94	5.1
Length of dorsal base to adipose	14.0 12.2–16.3 2.08	12.8
Length of pre-adipose to snout	62.1 60.0–63.5 1.92	62.6
Dorsal-fin length	20.3 19.4–21.9 1.40	19.8
Pectoral-fin length	29.2 28.7–29.6 0.49	25.0
Pelvic-fin length	20.5 19.7–21.8 1.10	18.5
Anal-fin length	15.4 14.5–16.5 1.02	14.7
Length of anal-fin base	5.9 4.5–7.0 1.32	6.3
Caudal-fin length	15.8 15.3–16.5 0.67	15.2
Length of adipose-fin base	33.0 29.5–38.5 4.82	30.1
i n% head length
Snout length	51.1 49.1–52.9 1.90	50.8
Eye diameter	9.1 7.3–10.4 1.64	7.1
Interorbital width	27.2 26.2–29.1 1.63	26.4
in% Pt-Pl length
Length of pectoral fin	101.3 97.1–109.1 6.77	101.7
in% Pl-A length
Length of pelvic fin	73.4 70.8–74.7 2.22	84.5
in% length of caudal peduncle
Depth of caudal peduncle	23.2 21.6–25.3 1.91	20.4