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

Xu Li, Wei Zhou, Alfred W. Thomson, Qing Zhang & Ying Yang, 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 0311021 , 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 0311022, 0311024 (2; 78.0-99.6 mm TL, 66.0-85.2 mm SL), same data as holotype. SWFC 0303248 (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. macropterus by the following characters: premaxillary tooth patches appear joined with median indentation (vs. separate) (Fig. 2A); lower lip connected to base of maxillary barbel by skin flap, without sulcus between them (vs. not connected, with sulcus) (Fig. 3A). It differs from P. gracilicaudata , P. longicauda , P. macrotrema , P. myzostoma , P. robusta and P. sinensis 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. myzostoma , 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. sinensis 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. macrotrema 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. sinensis 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. myzostoma 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. 2A). 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. 3A).

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).