Pareuchiloglanis myzostoma (Norman)

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 : 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 0 209001 (1; 115.1mm SL), Yingpan, Lanping County, Yunnan Province.

Diagnosis. Characters distinguishing Pareuchiloglanis myzostoma from P. abbreviatus , P. gracilicaudata , P. k a m e n g e n s i s 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. 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, and without sulcus between them (vs. not connected, with sulcus) ( Fig. 3 A). 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. s i n e n s i s 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 ).

Figures

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.

FIGURE 7. Pareuchiloglanis myzostoma, SWFC 0 209001, 115.1 mm SL; Yingpan, Lanping county, Yunnan province, China. Dorsal, lateral and ventral views.