Leptobotia bellacauda, Bohlen, Jörg & Šlechtová, Vendula, 2016

Bohlen, Jörg & Šlechtová, Vendula, 2016, Leptobotia bellacauda, a new species of loach from the lower Yangtze basin in China (Teleostei: Cypriniformes: Botiidae), Zootaxa 4205 (1), pp. 65-72 : 65-72

Leptobotia bellacauda , new species

( Fig. 1 )

Material examined. Holotype: SNHM 20160220 , male, 70.1 mm SL; China, Anhui province, Qiupu River in Shitai County (Yangtze drainage); 31 July 2015 . Paratypes: SNHM 20160221‒20160224, 4 specimens, 1 male, 3 females, 64.6‒76.7 mm SL, ZRC 54802, 2, 1 male, 1 female, 71.7‒73.4 mm SL; same data as holotype. SNHM 20160225, 1 specimen, 47.6 mm SL , IAPG A8651‒8655, 5 specimens, 35.9‒87.6 mm SL, same locality as holotype, 22 September 2013 . Additional material (non-type): IAPG A10062 , 1 specimen, male, 64.7 mm SL, China, Anhui province, Ningguo county, stream close to Ningguo city (Yangtze drainage), 0 2 May 2015 .

Diagnosis. Leptobotia bellacauda is distinguished from all other species of Leptobotia by the combination of the following characters: body plain brown, pigmentation pattern restricted to a prominent thick black bar on the caudal fin, a thinner black bar at the base of the caudal fin, a black base of the dorsal fin, a black stripe on the dorsal fin and a fine black stripe from snout to eye; dorsal half of head dusky black, ventral half cream, sharply demarcated; origin of dorsal fin above or slightly posterior of the pelvic-fin origin; 8 ½ branched rays in the dorsal fin; 7 rays in the pelvic fin; eye well developed but small (eye diameter 2.2‒3.1 % SL) and caudal fin moderately emarginated with rounded lobes (length of median rays 1.6‒2.0 times in length of those of lower lobe). The pectoral fin in adult males enlarged, with numerous tubercles on its dorsal surface.

Description. See Figure 1 for general appearance and Table 1 for morphometric data.

Habitus relatively small, body elongated (body depth 4.8‒7.6 times in SL). Head strongly compressed; body, caudal peduncle compressed. Greatest body depth between nape and dorsal-fin origin (maximum body depth 100- 1007% of body depth at dorsal origin). Depth of caudal peduncle 1.2‒1.5 times in its length. Axillary pelvic lobe present, free. No adipose crest on dorsal and ventral midline of caudal peduncle. Largest known size 87.6 mm SL.

Dorsal fin with 4 simple and 8½ branched rays. Distal margin of dorsal fin straight or slightly convex. Anal fin with 3 simple and 5½ branched rays, not reaching half of distance between end of anal-fin base and caudal-fin base when adpressed. Caudal fin with 9+8 branched rays, deeply forked (length of median rays 1.5‒1.9 times in length of upper lobe), lobes rounded. Pelvic fin with 8 rays; origin anterior to or on vertical through dorsal-fin origin; in males reaching half of distance to anal-fin origin, beyond anus; but not or just reaching anus in females. Anus situated closer to pelvic-fin base than to anal-fin origin. Pectoral fin with 11‒13 rays, usually not reaching half of distance between bases of pectoral and pelvic fins. Vertebral column with 4+37 vertebrae (4 comprising the swimbladder complex; urostyle included into counts as one) in seven radiographed specimens.

Body covered by small scales except on ventral side, between pectoral fins. Length of lateral line varying from ending above base of anal fin to nearly complete; pores small, difficult to visualise, unevenly scattered along lateral line, numbering between 41‒76. Cephalic lateral-line system with 7 supraorbital, 4+9 infraorbital, 12 pre-operculomandibular and 3 supratemporal pores. Lips, barbels smooth, not covered with unculi.

Anterior nostril pierced in front side of a flap-like tube, not reaching margin of eye, with a low anterior rim. Eyes moderately large (7.0‒9.9 times in lateral head length), eye diameter 1.0‒1.6 times in interorbital width. Mouth gape about twice as wide as long. No notch in jaws. Lips moderately thick; no median incisions or furrows. Inner and outer rostral barbel reaching half distance to base of maxillary barbel; maxillary barbel reaching beyond vertical through anterior rim of pupil.

Suborbital spine inserted on vertical through anterior margin of eye, reaching vertical through posterior margin of eye, simple, without side branch, moderately curved ( Fig. 2 ).

Sexual dimorphism. Adult males with larger pectoral fins than females (pectoral-fin length 14.6‒16.4% SL vs 10.7‒12.9% SL); first (unbranched) pectoral-fin ray and following 4‒7 branched pectoral-fin rays with numerous tiny tubercles along their dorsal surface in males ( Fig. 3 b).

Coloration. In most preserved specimens ground colour of body and dorsal side of head light brown to olive, only darker on dorsal side. One specimen ( Fig. 1 d) with greyish body and head with only ventral side lighter. Ventral half of head white. Narrow black stripe from snout to eye; broad black bar on base of caudal fin, usually wider than eye diameter, reaching dorsal and ventral midline. A prominent black bar on caudal fin; usually located on the distal half of fin, its shape retracing posterior margin of fin. In a single specimen (holotype) tips of caudalfin lobes black. Width and contrast variable, always wider than bar on base of caudal fin; in two larger specimens dissociating into two bars. One black stripe on base of dorsal fin and one on dorsal fin, located on the distal half of fin; interradial membrane hyaline. Usually a weak stripe present in the anal fin and in one paratype also in the pelvic fin; body pigmentation otherwise absent. Lips, barbels white.

Colour in life slightly more vivid, ground colour between light brown and coffee brown.

Distribution. At present only known from two locations in Anhui Province, China. Both streams drain northwards and into the Yangtze River ( Fig. 4 ). An impression of the habitat is given by Fig. 5 .

Etymology. From Latin ‘ bella’ for ‘beautiful’ and ‘ cauda’ for ‘tail’; a reference to the prominent pigmentation on the caudal fin. An adjective.

Comparisons. All species of Botiidae have an erectable suborbital spine, a formation of the lateral ethmoid. In most species this spine is bifid, meaning that it has a main branch (processus ventrocaudalis) and a sidebranch (processus dorsacaudalis). A simple suborbital spine is found only in all 13 species of Leptobotia and in Sinibotia zebra ( Wu 1939; Chen 1980; Nalbant 2002) and is considered a diagnostic character for Leptobotia . Species of Leptobotia differ from S. zebra by the absence of mental barbels on the lower lip ( Fang 1936; Wu 1939; Chen 1980; Li et al. 2008; Nalbant 2002; Xu et al. 1981). The suborbital spine of L. bellacauda is simple and its lower lip does not exhibit mental barbels, demonstrating that it is a member of the genus Leptobotia .

The most prominent character of L. bellacauda is the lack of any body pigmentation, together with the presence of two pronounced black bars, one on the base of the caudal fin and the other on the caudal fin. Of the 13 species of Leptobotia considered valid by Kottelat (2012), eight have bars on the body or at least saddles on the dorsum ( L. elongata , L. flavolineata Wang , L. guilinensis , L. hengyangensis Huang & Zhang , L. orientalis Xu et al, L. pellegrini Fang , L. rubrilabris Dabry de Thiersant , L. tchangi Fang ), one ( L. punctata ) has spots on the sides and one ( L. taeniops (Sauvage)) a marbled or vermiculated pigmentation pattern with faint saddles ( Fang 1936; Wu 1939; Chen 1980; Li et al. 2008; Nalbant 2002; Xu et al. 1981). Leptobotia bellacauda differs from all these species by having (vs. not having) two black bars, one on the caudal-fin base and another on the caudal fin itself.

Only three species within the genus Leptobotia ( L. microphthalma Fy & Ye , L. posterodorsalis and, L. tientaiensis (Wu)) have a plain brown body. Leptobotia bellacauda differs from L. microphthalma by having larger eyes (eye diameter 2.1‒3.1 % SL vs. 0.8‒1.0 % SL), a less deep emarginated caudal fin (length of median rays 1.5‒2.0 times in length of those on lower lobe, vs. 2.7‒3.1 times), presence (vs. absence) of a black stripe from snout to eye, and by having a black bar on the caudal-fin base and another on the caudal fin (vs. having all fins in the same colour as the body). Leptobotia bellacauda shares with L. posterodorsalis the general pigmentation pattern (plain brown body with two prominent black bars on caudal-fin base and caudal fin, respectively), but differs from L. posterodorsalis by having the pelvic fin inserted opposite or slightly in advance of the dorsal-fin origin (vs. distinctly anterior to dorsal-fin origin); more branched rays in the dorsal fin (8 vs. 6‒7) and the pelvic fin (7 vs. 6); long, pointed (vs. short and rounded) fins; a distinct (vs. faint) black stripe from snout to eye; and the outer margin of the dorsal fin straight (vs. convex). Leptobotia bellacauda differs from L. tientaiensis by having the anus closer to pelvic-fin base than to anal-fin origin (vs. closer to anal-fin origin), a much more compressed head (head width at nares 4.3‒5.6% SL vs. 7.2% SL), larger interorbital width (2.8‒3.8 vs. 4.3% SL); a broad black bar on caudal-fin base (wider than eye diameter vs. narrower than eye diameter); and distinct black bars on the dorsal and caudal fin (vs. hyaline fins with dots, blotches or indistinct marbling).

Comparative material. Leptobotia guilinensis : IAPG A8861‒8883, 23 specimens, 62.7‒80.3 mm SL; China: Guangxi: Li River . Leptobotia hengyangensis : IHASW 80013, syntype, 1; China: Hunan: Xiang River (by photographs). Leptobotia microphthalma : IAPG A8536‒8543, 9 specimens, 66.3‒81.4 mm SL ; China: Sichuan: Min River . Leptobotia punctata : IAPG A9101, 1 specimen, 53.2 mm SL ; China: Guangxi: Yong River . Leptobotia tientaiensis : IHASW 790940 (syntype of L. tientaiensis hansuiensis ), 1, China: Shaanxi: Langao (by photographs) ; IAPG A9173, 1 specimen, 51.3 mm SL; China: Zhejiang: Ling River . Leptobotia tchangi : IAPG 9167‒9172, 6 specimens, 62.6‒111.8 mm SL, China: Zhejiang: Qiantang River . Further data taken from Aquatic Research Institute of Guangxi (2006), Li et al. (2008), Xu et al. (1981), and Ye et al. (2015).

Figures

FIGURE 1. Leptobotia bellacauda; China: Anhui province, a ‒ b, SNHM 20160220, holotype, male, 70.1 mm SL; c ‒ d, SNHM 20160221 ‒ 20160224, paratypes, c, female, 64.6 mm SL, d, female, 76.7 mm SL.

FIGURE 2. Leptobotia bellacauda; IAPG 8651, 87.6 mm SL; right suborbital spine, dorsal view. Scale bar 1 mm.

FIGURE 3. Leptobotia bellacauda, sexual dimorphism; a, SNHM 20160221 ‒ 20160224, paratypes, size difference of pectoral fin, left female 64.6 mm SL, right male 70.7 mm SL; b, IAPG A 8654, 46.8 mm SL, paratype, male; left pectoral fin in dorsal view. The majority of fin rays are covered with small tubercles (absent in females).

FIGURE 4. Rough distribution of species of Leptobotia in China and northern Vietnam. Red dotted line: L. elongata, L. rubrilabris and L. taeniops; green dotted line: L. microphthalma; black dotted line: L. pellegrini; purple dotted line: L. tchangi; 1 — L. flavolineata; 2 — L. guilinensis; 3 — L. hengyangensis; 4 — L. orientalis; 5 — L. posterodorsalis; 6 - L. punctata; 7 — L. tientaiensis. Red asterisks indicate the known localities of the new species Leptobotia bellacauda.

FIGURE 5. Qiupu River in Anhui province, China. Type locality of Leptobotia bellacauda.

Tables

TABLE 1. Morphometric data of holotype (SNHM 20160220) and 12 paratypes (SNHM 20160221 - 20160224, SNHM 20160225, ZRC 54802, IAPG A 8651 - 8655) of Leptobotia bellacauda. Range, mean and SD include holotype.

	holotype	range	mean	S.D.
SL (mm)	70.1	35.9‒87.6
In percentage of standard length
Total length	121.4	119.4‒121.4	120.4	0.6
Dorsal head length	16.7	16.0‒19.0	17.4	0.8
Lateral head length	21.0	19.7‒23.1	21.3	1.1
Predorsal length	53.9	51.2‒59.0	55.9	2.0
Pre-pelvic length	51.1	50.5‒57.8	53.1	2.0
Pre-anus length	63.5	59.6‒69.3	64.4	2.6
Preanal length	73.9	71.4‒79.6	75.6	2.1
Head depth at eye	9.1	8.4‒9.7	9.2	0.4
Head depth at nape	12.3	11.7‒13.1	12.3	0.3
Maximum body depth	16.0	16.0‒18.2	16.9	0.7
Body depth at dorsal-fin origin	16.0	13.1‒20.7	16.6	1.8
Depth of caudal peduncle	12.6	11.0‒13.0	12.4	0.5
Length of caudal peduncle	17.5	14.2‒18.2	16.7	1.1
Snout length	7.6	7.1‒8.1	7.6	0.3
Head width at nares	4.6	4.3‒5.6	4.7	0.4
Maximum head width	8.7	8.0‒9.7	9.0	0.5
Body width at dorsal origin	8.7	6.0‒11.6	9.1	1.5
Body width at anal origin	7.1	4.3‒7.3	6.4	0.9
Eye diameter	2.4	2.1‒3.1	2.5	0.2
Interorbital width	3.3	2.8‒3.8	3.3	0.3
Height of dorsal fin	13.7	8.8‒14.6	12.2	1.6
Length of upper caudal lobe	20.5	19.0‒21.6	19.8	0.7
Length of median caudal ray	11.8	10.0‒13.6	11.6	1.0
Length of lower caudal lobe	20.7	18.7‒20.9	19.9	0.7
Depth of anal fin	15.3	13.8‒16.2	14.7	0.8
Length of pelvic fin	13.4	9.7‒13.4	11.7	1.0
Length of pectoral fin	16.4	10.7‒16.4	13.1	1.7