Schistura paraxena, Endruweit, 2017

Endruweit, Marco, 2017, A new Schistura from the Pearl River in Guangxi, China (Teleostei: Nemacheilidae), Zootaxa 4277 (1), pp. 144-150 : 145-147

Schistura paraxena , new species

Figs. 1 , 2

Holotype. KIZ 2005010297, 70.3 mm SL; China: Guangxi Prov.: Laibin Pref.: Jinxiu Cty.; Pearl River: Xi River: Changdonghe River ; about 24°05'N, 110°04'E, coll. Kong, D.P. & Yang, J., 21 Oct. 2005.

Paratypes. KIZ 2005010287, 289-291 , 293-296, 298, 9 specimens, 32.3–69.6 mm SL; data as for holotype; KIZ 2005006321-6327, 7 , 47.8–66.3 mm SL; China: Guangxi Prov.: Laibin Pref.: Jinxiu Cty.: Meicun village; Pearl River: Xi River : Jinxiuhe River ; coll. Kong, D.P. & Yang, J., 15 Oct. 2005.

Diagnosis. Schistura paraxena is distinguished from its congeners in having conspicuous peduncular crests along its dorsal and ventral extremities and a plain beige body coloration with crests brownish gray and a pale spot medially at caudal-fin base. Further characters useful to diagnose the species are: 8½ branched dorsal-fin rays; 11– 12 [11] pectoral-fin and 9 pelvic-fin rays; 37-38 [38] vertebrae; predorsal length 50–52% SL; caudal-peduncle length 17–18% SL (88–92% HL; 5.6–5.8 times SL); lateral line complete; breast naked; predorsal area scaled; and upper lip not notched.

Description. See Figures 1 and 2 for general appearance and Table 1 for morphometric data. Body predorsally cylindrical, postdorsally laterally compressed; elongate, depth 6.0–6.8 times in SL. Maximum body depth immediately in front of dorsal fin. Caudal peduncle long, depth 1.2–1.3 times in its length; crests on dorsal and ventral midline present, starting approximately 1.5 eye diameter behind dorsal-fin and anal-fin bases, not supported by procurrent caudal-fin rays. Axillary pelvic lobe present, free. Anus located 1.6–2.7 times eye diameter in front of anal-fin origin. Snout blunt. Cheek not inflated. Head width constantly increasing from nostril to about edge of preoperculum. Eye large; located dorsolaterally, not reaching dorsal profile when viewed laterally. Interorbital space slightly convex, wide. Anterior nostril with a flap-like tube, not pierced, not reaching orbit. Suborbital lobe absent. Mouth inferior, gape 1.5–1.8 times wider than long. Lips thick, fleshy, furrowed; lower lip notched medially. Upper jaw with rounded processus dentiformis; lower jaw spoon-like, notched medially. Medial rostral barbel failing to reach rictus, lateral reaching rictus. Maxillary barbel reaching past vertical through posterior rim of orbit. No tubercles on head and body.

Vertebrae 37–39 [38] (n=16); 18–19 [18] abdominal and 18–21 [19] caudal. Gas bladder in ossified capsule; dumbbell-shaped; no secondary chamber. Gastrointestinal tract with simple, U-shaped stomach; intestines with single loop immediately after stomach. Largest recorded length 70.3 mm SL, 83.7 mm total length (KIZ 2005010297, holotype).

Scales small, sparsely set on nape; breast naked with few scales around pectoral-fin base. Lateral line complete, reaching caudal-fin base, with 118–136 pores. Cephalic lateralis system with 8 supraorbital, 4+10–11 infraorbital, 10 preoperculo-mandibular and 3 supratemporal pores.

Dorsal fin with 4 simple 8½ branched rays; distal margin slightly convex. Anal fin with 3 simple and 5½ branched rays; distal margin convex; not reaching caudal-fin base. Caudal fin slightly emarginate, with 9+8 branched rays; lobes equal, rounded. Pelvic fin 9 rays, reaching anus, inserted opposite last unbranched dorsal-fin ray; fourth ray longest; distal margin convex. Pectoral fin with 11-12 [11] rays, reaching past midway to pelvic-fin origin; fifth ray longest; distal margin convex.

Coloration of preserved specimens. Body plain beige, abdomen paler. No markings, except for a few inconspicuous, irregularly shaped and spread, brown speckles in specimens larger than 65 mm SL. Crests on caudal peduncle brownish gray. Caudal bar variable, usually reduced to an inconspicuous pale gray spot at midline; caudal bar pale, thin, straight, not reaching dorsal and ventral extremities in few (2 of 17) specimens. Head plain beige; top gray; operculum russet. Dorsal fin beige with a somewhat conspicuous dusky anterobasal spot, a low dusky basal band and a medial broad transverse dusky band. Caudal fin beige with 1–2 broad transverse dusky bands. Other fins plain beige.

Distribution. Schistura paraxena is only known from the type locality, the Changdonghe River, an affluent of the West River, Pearl River drainage ( Fig. 3 ).

Ecology. Specimen KIZ 2005010298, 65.0 mm SL, was dissected. The stomach contained remains of nymphs of the stonefly family Perlidae .

Etymology. From the Greek παράξενος (paraxenos), meaning strange; in reference to the species’ unusual appearance. An adjective, Latinized (-us, -a, -um).

Figures

FIGURE 1. Schistura paraxena, KIZ 2005010297, holotype, 70.3 mm SL; Guangxi: Jinxiu; Changdonghe River.

FIGURE 2. Schistura paraxena, paratypes; Guangxi: Jinxiu; Changdonghe River; upper, KIZ 2005010290, 69.9 mm SL; lower, KIZ 2005010296, 66.0 mm SL.

FIGURE 3. Map of the Pearl River drainage; 1, West River; 2, North River; 3, East River. Symbol indicates the type locality of Schistura paraxena.