A New Cavefish Species from Southwest China, Sinocyclocheilus Gracilicaudatus Sp

Zootaxa 3768 (5): 583–590 ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ Article ZOOTAXA Copyright © 2014 Magnolia Press ISSN 1175-5334 (online edition) http://dx.doi.org/10.11646/zootaxa.3768.5.5 http://zoobank.org/urn:lsid:zoobank.org:pub:F084C67C-2187-49E4-AD5B-A5848FEC1CD9 A new cavefish species from Southwest China, Sinocyclocheilus gracilicaudatus sp. nov. (Teleostei: Cypriniformes: Cyprinidae)

DAN WANG1,2,3,4, YAHUI ZHAO2,5, JUNXING YANG1 & CHUNGUANG ZHANG2,5 1Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, China 2Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China 3Graduate University of Chinese Academy of Sciences, Beijing, 100049, China 4Fishery Bureau, Ministry of Agriculture of the People’s Republic of China, 100125, China 5Corresponding author. E-mail: [email protected]; fish@ioz.ac.cn

Abstract

One new species is added to the genus Sinocyclocheilus, the largest cyprinid genus in China and the largest cavefish genus in the world. Sinocyclocheilus gracilicaudatus sp. nov. is similar to S. donglanensis but differs to other congeners in having normal eyes and scaled body, curved lateral line with 59–64 lateral-line scale rows, half-hard dorsal fin spine, 8 gill rakers and 8 predorsal vertebrae. Compared to S. donglanensis, the new species has a longer and more narrow caudal peduncle (caudal peduncle length 21.3-22.7% vs. 16.8–20.4% of SL; caudal peduncle depth 10.5–12.0% vs. 12.5–15.5% of SL), smaller eyes (eye diameter 5.8–8.3% vs. 6.5–10.9% of SL) and longer barbels (maxillary barbel length 16.6–24.3% vs. 11.1–21.1 % of SL; rictal barbel length 19.5–21.6% vs. 11.3–21.1% of SL). The new species is distributed in a subterranean river, belonging to the Longjiang River system; S. donglanensis occurs in the Hongshuihe River system, a system separate from that where the former species occurs.

Key words: Sinocyclocheilus, new species, cavefish, China

China has a very rich species diversity of cavefish, with more than 90 troglobite and troglophile species (Romero, et al., 2009; Zhao & Zhang, 2006). Southwest China including Yunnan, Guangxi and Guizhou provinces is the main area of distribution of these cavefishes (Romero, et al., 2009). Typical a karst geology and environment, suitable climate and hydrological condition, and a complicated hypogean water system, are the primary factors responsible for great diversity of cavefish species in general and more specifically in China (Zhao & Zhang, 2006). The genus Sinocyclocheilus is monophyletic and endemic to China. It is also the most species-rich genus of cyprinid fishes in China, with more than 60 species having been described, of which 49 are recognized as valid. Also, all species of Sinocyclocheilus have various cave-dwelling behaviors (Zhao & Zhang, 2009). Recently, three specimens collected in Guangxi Province have enabled us to recognize the new species described herein.

Material and methods

Type and comparative specimens are deposited in the fish collection of National Zoological Museum, Institute of Zoology, Chinese Academy of Sciences (ASIZB) (Leviton, et al., 1985). Measurements were taken point to point with a digital caliper to 0.1 mm. Morphometric and meristic characters were selected following methods described in Zhao et al. (Zhao, et al., 2006). Specimens were radiographed with Kodak DXS 4000pro X-ray System. Dorsal, anal and caudal-fin rays and vertebrae were counted from these radiographs. Vertebral counts presented exclude those of the Weberian complex.

Accepted by R. Mayden: 15 Oct. 2013; published: 28 Feb. 2014 583 Sinocyclocheilus gracilicaudatus Zhao and Zhang, sp. nov. Figure 1

Holotype: ASIZB 186399, 94.7mm standard length (SL), Zhujiang (Pearl) River Basin, Donglei Cave, Mulun town, Huanjiang County, Guangxi Zhuang Autonomous Region, China; 2009; collected by M. Y. Tian Paratype: ASIZB 186400, 79.0mm SL, ASIZB 186401 (preserved in collection of South China Agricultural University) 60.8mm SL, same data as for holotype. Diagnosis. The new species can be distinguished from other known congeners by the following combination of characteristics: body normal shape; eyes present, normal; well scaled excluding head; lateral-line curved, scales 59–64; half-hard dorsal-fin spine; 8 gill rakers; 8 predorsal vertebrae; caudal peduncle length 21.3–22.7% of SL; caudal peduncle depth 10.5–12.0% SL.

FIGURE 1. Sinocyclocheilus gracilicaudatus sp. nov. Holotype 186399, ASIZB, 94.7mm SL, scale bar 10mm

Description. General body characters are shown in Figure 1. Meristic features and proportional measurements as percentages of standard length are listed in Table 1. Body moderately elongate and compressed. Dorsal profile convex from snout to dorsal fin, greatest body depth at dorsal fin insertion, and being slightly concave from end of dorsal-fin base to caudal fin. Ventral profile concave, tapering gradually toward anal fin. Head compressed. Two pairs of nostrils, anterior and posterior nostrils neighbored, front edge of anterior nostril midway from snout tip to front edge of eye; anterior-nostril possessing a rim with a fleshy flap forming a small tube. Mouth curved and slightly sub-inferior. Two pairs of barbels; insertion of maxillary barbel in front of anterior nostril, barbel long, extending to middle part of operculum; rictal barbel long, reaching posterior margin of operculum. Eye present and well developed, round, anterior and posterior edge of orbit at one third and half distance between snout tip to posterior margin of operculum, respectively. Cranial sensory canals developed, superaorbital and infraorbital canals connected. Gill opening large. Gill rakers triangular, well developed, 8 on first gill arch, 2 and 6 on epibranchial and ceratobranchial respectively. Pharyngeal teeth in three rows with counts of 1,3,4-4,3,1 (one specimens checked), pharyngeal teeth at outer row strong and well developed, with curved and pointed tip. Pectoral-fin insertion under posterior margin of operculum, pectoral fin not reaching pelvic fin insertion. Pelvic-fin insertion opposite dorsal-fin insertion; pelvic fin long, reaching four fifths of distance from pelvic-fin insertion to anus. Dorsal-fin a little closer to caudal fin base than to snout tip, last unbranched ray hard at base, softening toward tip, and with serrations along posterior edge. Anal-fin origin directly posterior to anus, reaching midway between anal-fin insertion to caudal fin base. Caudal-fin bifurcate.

584 · Zootaxa 3768 (5) © 2014 Magnolia Press WANG ET AL. Lateral-line complete and curved, descending to above pectoral-fin rays from posterior margin of operculum and ascending to body midline above anal-fin base where extends to end of caudal peduncle. Scales small. Lateral- line scales larger than other scales. Lateral-line scale rows 59–64; scale rows above lateral line 22–24; scale rows below lateral line 13; circumpeduncular scale rows 38. Predorsal scales irregularly arranged and difficult to count accurately. Coloration in alcohol.—Specimens were fixed in 10% formalin and then preserved in 75% alcohol. Dorsum dark grayish, abdomen light yellowish; no spots or blotches on body, head or fins; ventral aspect of caudal peduncle with very light black strip along midline from top of anus to base of caudal fin. Pectoral, dorsal and caudal fins grayish; anal-fin light grayish; pelvic-fin whitish. Distribution. Known only from a subterranean river of a cave in the town of Mulun, Huanjiang County, Guangxi Zhuang Autonomous Region, China. The subterranean river drains to the Longjiang River, a tributary of the Pearl River System (Fig. 2).

FIGURE 2. Sampling sites of Sinocyclocheilus gracilicaudatus sp. nov. (●) and S. donglanensis (▲).

Etymology. The name gracilicaudatus is a noun in apposition, derived from gracilis meaning slender and caudatus meaning tail, in reference to the narrow caudal peduncle and caudal fin. Discussion. Following the list of species of Sinocyclocheilus in Zhao et al. (2006), the new species can be distinguished from all other known species except for Sinocyclocheilus donglanensis, by having developed eyes, completely scaled body with a normal body shape, half-hard dorsal fin spine, curved lateral line with 59–63 lateral- line scales, relatively short pectoral fin, 8 gill rakers and 8 predorsal vertebrae. Sinocyclocheilus gracilicaudatus is most similar to S. donglanensis. These two species are easily distinguished. Sinocyclocheilus gracilicaudatus has a more slender and longer caudal peduncle length (21.3–22.7% vs. 16.8–20.4% of SL) and narrower caudal peduncle depth (10.5–12.0% vs. 12.5–15.5% of SL) relative to S. donglanensis (Fig. 3, Table 1). Interestingly, compared to S. donglanensis, Sinocyclocheilus gracilicaudatus has smaller eyes (eye diameter 5.8–8.3% vs. 6.5–10.9% of SL), but longer barbels (maxilla barbel length 16.6–24.3% vs. 11.1–21.1 % of SL and rectal barbel length 19.5–21.6% vs. 11.3–21.1% of SL) (Fig. 4, 5; Table 1). Moreover, principle component analysis (PCA) of morphometric characters also reveals the two species differing primarily on the basis of three additional characters, including length of the maxilla and rictal barbels and length of the lower jaw (Fig. 6, Table 2).

A NEW CAVEFISH IN CHINA Zootaxa 3768 (5) © 2014 Magnolia Press · 585 TABLE 1. Meristics and morphmetrics of Sinocyclocheilus gracilicaudatus sp. nov. and S. donglanensis. Sinocyclocheilus gracilicaudatus sp. nov. Sinocyclocheilus donglanensis N Min Max Mean SD Holotype N Min Max Mean SD Dorsal-fin rays 3 7 7 7 7 5 7 7 7 Anal-fin rays 3 5 5 5 5 5 5 5 5 Pectoral-fin rays 3 14 14 14 14 5 14 15 15 Pelvic-fin rays 3 8 8 8 8 5 9 9 9 Total vertebrae 3 37 39 38 38 5 37 38 37 Predorsal vertebrae 3 8 8 8 8 5 8 9 8 Caudal vertebrae 3 18 20 19 19 5 18 18 18 Gill rakers 3 8 8 8 8 5 8 9 9 Lateral-line scale rows 3 59 64 62 64 5 57 64 60 Scale rows above lateral line 3 22 24 23 24 5 23 25 24 Scale rows below lateral line 3 13 13 13 13 5 12 14 13 Circumpeduncular scale rows 3 38 38 38 38 5 38 44 42 Standard length 3 60.8 94.7 78.2 17.0 94.7 5 53.2 123.9 82.6 28.4 In % of standard length Body depth 3 22.7 27.7 25.4 2.5 25.9 5 28.5 35.9 31.1 2.8 Predorsal length 3 54.7 56.1 55.5 0.7 56.1 5 55.4 59.7 57.1 1.6 Dorsal-fin base length 3 12.1 12.8 12.6 0.4 12.1 5 11.7 13.1 12.4 0.6 Dorsal-fin length 3 19.0 23.1 21.1 2.0 21.2 5 19.7 24.0 21.6 1.9 Preanal length 3 71.4 76.0 73.9 2.3 74.4 5 75.1 79.7 77.2 1.7 Anal-fin base length 3 8.8 9.7 9.2 0.5 8.8 5 7.4 8.2 7.9 0.3 Anal-fin length 3 15.2 18.2 16.6 1.5 16.3 5 17.2 20.8 18.8 1.4 Prepectoral length 3 28.8 29.4 29.2 0.3 29.4 5 26.5 30.3 29.0 1.5 Pectoral-fin base length 3 3.4 3.9 3.6 0.3 3.9 5 4.3 4.7 4.5 0.2 Pectoral-fin length 3 21.3 21.9 21.5 0.4 21.3 5 19.7 24.6 22.9 1.9 Prepelvic length 3 53.0 55.2 54.3 1.1 53.0 5 52.8 55.4 54.5 1.1 Pelvic-fin base length 3 3.6 4.2 3.9 0.3 4.2 5 3.8 5.1 4.4 0.5 Pelvic-fin length 3 16.5 17.8 17.0 0.7 16.5 5 16.3 19.4 17.7 1.3 Caudal peduncle length 3 21.3 22.7 21.9 0.7 22.7 5 16.8 20.4 18.3 1.6 Caudal peduncle depth 3 10.5 12.0 11.1 0.8 10.5 5 12.5 15.5 13.6 1.1 Head length 3 27.4 28.9 27.9 0.8 27.4 5 26.6 29.5 28.2 1.2 Head depth 3 15.5 17.1 16.5 0.9 15.5 5 17.5 18.8 18.2 0.4 Head width 3 12.8 15.0 13.7 1.2 12.8 5 14.5 16.5 15.3 0.8 Snout length 3 8.5 9.5 8.8 0.6 8.4 5 7.2 9.0 7.9 0.7 Eye diameter 3 5.8 8.3 7.1 1.3 5.8 5 6.5 10.9 8.6 1.7 Interorbital width 3 7.7 8.3 7.9 0.3 7.7 5 7.4 8.7 7.8 0.6 Prenostril length 3 3.9 5.5 5.0 0.9 5.4 5 4.7 6.3 5.2 0.7 Width between posterior nostrils 3 4.0 5.0 4.6 0.5 5.0 5 5.2 6.0 5.5 0.3 Upper jaw length 3 7.3 7.7 7.5 0.2 7.4 5 6.2 7.4 6.8 0.5 Lower jaw length 3 4.0 4.8 4.3 0.4 4.2 5 5.7 6.7 6.1 0.4 Mouth width 3 4.9 5.5 5.3 0.3 5.5 5 6.0 7.3 6.8 0.5 Maxilla barbel length 3 19.6 24.3 22.1 2.4 19.6 5 11.1 21.1 14.3 4.1 Rictal barbel length 3 19.5 21.6 20.8 1.2 19.5 5 11.3 21.1 15.3 3.7

586 · Zootaxa 3768 (5) © 2014 Magnolia Press WANG ET AL. TABLE 2. Character loadings on principal components I and II for measurements from specimens of Sinocyclocheilus gracilicaudatus sp. nov. (3 specimens) and S. donglanensis (5 specimens). The three highest loadings on PC II are shown in boldface. PC I PC II Standard length 0.2807 -0.0107 Body depth 0.3278 0.1061 Predorsal length 0.2849 0.0087 Distance from head end to dorsal fin insertion (dorsal view) 0.319 -0.0048 Dorsal-fin base length 0.2932 -0.0188 Dorsal fin length 0.2273 0.0116 Preanal length 0.2917 0.0128 Anal-fin base length 0.254 -0.084 Anal fin length 0.2259 0.057 Prepectoral length 0.2485 -0.0041 Pectoral-fin base length 0.2807 0.1074 Pectoral fin length 0.2953 0.0242 Prepelvic length 0.2695 -0.0056 Pelvic-fin base length 0.3254 0.0506 Pelvic fin length 0.2435 0.0198 Caudal peduncle length 0.2697 -0.1038 Caudal peduncle depth 0.3204 0.0914 Head length 0.257 0.0004 Head depth 0.2651 0.0293 Head width 0.2973 0.0505 Snout length 0.3208 -0.0659 Eye diameter 0.1248 0.0956 Interorbital width 0.2861 -0.0138 Prenostril length 0.3779 0.0375 Width between posterior nostrils 0.2994 0.1015 Upper jaw length 0.2554 -0.0538 Lower jaw length 0.281 0.1645 Mouth width 0.2848 0.1255 Maxilla barbel length 0.385 -0.3002 Rictal barbel length 0.4144 -0.2159

Sinocyclocheilus gracilicaudatus is also distributed allopatrically from S. donglanensis. The former species occurs only in a cave and the subterranean river of the Longjiang River system, a tributary of the Pearl River system. Whereas Sinocyclocheilus donglanensis occurs in the Hongshuihe River system, another tributary of the Pearl River system. Based on morphology and DNA sequences, the genus Sinocyclocheilus could be divided into four clades, given the appellations “jii”, “angularis”, “cyphotergous”, and “tingi” (names of clades from species names representative of each clade.) Species of each clade have similar characteristics across each clade and they each have their own unique distributions with only very narrow overlap between the distributions of clades angularis and cyphotergous (Zhao & Zhang, 2009). Species of the “jii” clade have soft dorsal fin spines. Species of the “angularis” clade have a horn-like structure on the nape. Most species of the “tingi” clade have more than 70 lateral-line scale rows. Given the number of lateral-line scales (59–63), the new species is hypothesized to belong to the “cyphotergous” clade, although it does not have typical dorsal protuberance similar to a humpback (Romero, et al., 2009; Zhao & Zhang, 2009). The distribution of the new species is also in the range of the “cyphotergous” clade.

A NEW CAVEFISH IN CHINA Zootaxa 3768 (5) © 2014 Magnolia Press · 587 FIGURE 3. Comparison of caudal peduncle depth vs caudal peduncle length between Sinocyclocheilus gracilicaudatus sp. nov. (×) and S. donglanensis (○).

FIGURE 4. Comparison of eye diameter relative to standard length between Sinocyclocheilus gracilicaudatus sp. nov. (×) and S. donglanensis (○).

588 · Zootaxa 3768 (5) © 2014 Magnolia Press WANG ET AL. FIGURE 5. Comparison of maxilla-barbel length and rictal barbel length relative to standard length for Sinocyclocheilus gracilicaudatus sp. nov. (×) and S. donglanensis (○).

FIGURE 6. Principal component analysis based on morphometric characters of Sinocyclocheilus gracilicaudatus sp. nov. (●) and S. donglanensis (○) .

Comparative materials. Sinocyclocheilus donglanensis: ASIZB 94976, holotype, 98.1mm SL, ASIZB 74217, 74218, 94747, 94748 (4 specimens), paratypes, 53.2–123.9mm SL, Zhujiang River basin: Hongshuihe River, Gongping Village, Taiping Town, Donglan County, Guangxi Zhuang Autonomous Region, China; 7 Oct 2002, by C. G. Zhang and K. Watanabe.

We give our many thanks to M. Y. TIAN (Professor, South China Agricultural University). This work was supported by grants of the National Natural Science Foundation of China (NSFC-31071884 and NSFC-30870285).

References

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