Pareuchiloglanis myzostoma (Norman)

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 : 13-15

Pareuchiloglanis myzostoma (Norman)

(Fig. 7)

Euchiloglanis myzostoma Norman, 1923 : 562-563 (Yunnan); Hora & Silas: 1951, 16 (Lancangjiang drainage); Hora & Silas, 1952: 314-318 (Lancangjiang drainage).

Euchiloglanis feae myzostoma : Chu, 1979: 77 (Lancangjiang drainage).

Pareuchiloglanis myzostoma : Chu, 1981: 27; Chu, 1986: 41 (Lancangjiang drainage); Chu et al., 1990: 210 (Lanping, Yunnan); Chen, 1998: 310-311; Chu & Mo 1999: 170 (Lanping, Yunnan).

Material examined. BMNH 1923.2.21.40-49 (10 syntypes; 61-107.9mm SL), Lanping County, Yunnan Province. SWFC 0209001 (1; 115.1mm SL), Yingpan , Lanping County, Yunnan Province.

Diagnosis. Characters distinguishing Pareuchiloglanis myzostoma from P. abbreviatus , P. gracilicaudata , P. kamengensis and P. prolixdorsalis are summarized in Table 1. Morphometric and meristic data are in Table 3. 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); gill opening not extending ventrally beyond third pectoral-fin ray (vs. reaching base of first pectoral ray); 7 upper + 8 lower branched caudal-fin rays (vs. 6+7); dorsal fin i-5-6 (vs. i-7); anal fin ii-4 (vs. ii-8); distance between pelvic-fin origin to anal-fin origin shorter than distance between pelvic-fin origin to mouth (vs. equal); pectoral fin not reaching pelvic-fin origin (vs. reaching or beyond); pelvic fin not reaching anus (vs. reaching); origin of pelvic fin opposite end of dorsal-fin base (vs. behind dorsal-fin base); anus nearer anal-fin origin than posterior end of pelvic-fin base (vs. nearer to posterior end of pelvic-fin base); origin of anal fin nearer to caudal-fin base than to posterior end of pelvic-fin base (vs. nearer to posterior end of pelvic-fin base); snout length 47.2- 52.0% HL; head length 22.6-28.6% SL; caudal peduncle depth 5.3-5.9% SL.

Pareuchiloglanis myzostoma 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, and without sulcus between them (vs. not connected, with sulcus) (Fig. 3A). It differs from P. abbreviatus and P. anteanalis by its shorter pectoral fin, pectoral fin not reaching origin of pelvic fin (vs. 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), and differs from P. abbreviatus and P. prolixdorsalis by having 7+8 branched caudal-fin rays (vs. 6+7). It differs from P. songmaensis by the following characters: less fin rays, dorsal fin i-5-6, anal fin ii-4 (vs. i-7, ii-8); distance between pelvic-fin origin to anal-fin origin shorter than that to mouth (vs. equal); a longer head, head length 22.6-28.6% SL (vs. 21.5% SL). It differs from P. longicauda and P. sinensis by having origin of pelvic fin opposite to end of dorsal-fin base (vs. posterior to end of dorsal-fin base). Pareuchiloglanis myzostoma differs from P. gracilicaudata by having its pelvic fin not reaching anus (vs. reaching) and its shorter snout, 47.2- 52.0% HL (vs. 58.3-81.3% HL). It differs from P. abbreviatus , P. anteanalis , P. feae , P. longicauda , P. nebulifer , P. prolixdorsalis and P. rhabdurus by having anus nearer to origin of anal fin (vs. nearer to posterior of pelvic-fin base). It differs from P. rhabdurus and P. robusta by having the origin of anal fin nearer to caudal-fin base (vs. nearer to posterior of pelvic-fin base). Pareuchiloglanis myzostoma differs from P. longicauda by having gill openings extending ventrally beyond third pectoral-fin ray (vs. reaching first pectoral-fin ray base) and from P. rhabdurus by its deeper caudal peduncle, depth 5.3-5.9% SL (vs. 4.2% SL).

Distribution. Known only from the upper Lancangjiang [Mekong] drainage (Fig. 4).

Remarks. The syntypes of Pareuchiloglanis myzostoma were only cursorily recorded to be collected from Yunnan (Norman 1923). After reviewing the exploration route of Gregory (Gregory & Gregory 1923) in China and the resulting revision of glyptosternine catfish by Hora & Silas (1951), Chu & Mo (1999) examined the exploration route of Gregory and took a field survey. Chu considered that Loma Ho recorded by Hora & Silas (1951) was types locality of Pareuchiloglanis myzostoma , and Loma Ho must be the Lamahe (now called Jiduhe) in Lanping county, Yunnan (Chu & Mo 1999). The counts and other proportional measurements of one topotype of P. myzostoma are consisted with 10 syntypes preserved in British Museum of Natural History (Table 3).