First record of the catfish genus Amblyceps Blyth, 1858 from China with the description of a new species (Osteichthyes: Amblycipitidae).
Key words: Amblyceps yunnanensis, new species, Irrawaddy, China
The great majority of catfishes live only in freshwater; they can be easily identified by having body covered with thick mucus; barbells extending from each side of the jaws; adipose dorsal-fin usually present, mostly without rays (Chu et al. 1999). The genus Amblyceps, proposed by Blyth in 1858, is a group of diminutive freshwater catfishes. Amblycipitidae, which can be found in south and southeast Asia, typically inhabit swift streams or faster-flowing stretches of river drainages. According to Chen & Lundberg (1995), Amblyceps species possess the following synapomorphies: the presence of an epiphyseal commissure of the supraorbital sensory canals immediately anterior to, and not passing through the epiphyseal bar; anterior cranial fontanel narrowing abruptly along its posterior end, offering epiphyseal commissure bony support from the frontals; fifth ceratobranchial expended posteromedially; pinnate process present along anterior margin of the procurrent and median caudal-fin rays; transverse ridge along entire posterior margin of roof on supraoccipital and pterotic; lateroposterior process of horizontal lamina of urohyal short or vestigial, shorter than horizontal lamina; anterior nostril situated immediately anterior to base of nasal barbel; both lips with double folds. Additionally, it can also be differentiated by a distinctive cup-like structure above the pectoral-fin base, where the gill membrane rests when the gill-opening is closed (Hora 1933).
Currently, there are 19 valid species of Amblyceps, and four of them (A. apangi, A. murraystuarti, A. torrentis and A. cerinum) are characterized by caudal-fins truncate and emarginate. The other 15 species have caudal-fins deeply forked, namely, A. arunachalensis Nath & Dey, 1989; A. mangois Hamilton, 1822; A. laticeps M'Clelland, 1842; A. caecutiens Blyth, 1858; A. foratum Ng & Kottelat, 2000; A. mucronatum Ng & Kottelat, 2000; A. platycephalus Ng & Kottelat, 2000; A. tenuispinis Blyth, 1860; A. serratum Ng & Kottelat, 2000; A. variegatum Ng & Kottelat, 2000; A. macropterus Ng, 2001; A. kurzii Day, 1872; A. protentum Ng & Wright, 2009; A. carinatum Ng, 2005; A. tuberculatum Linthoingambi & Vishwanath, 2008. Among the 19 species, none of them are known to inhabit in China.
In August 2011, some Amblyceps specimens with truncate caudal-fins were collected from downstream of the River Mengnai (a tributary of upper Irrawaddy basin), Nabang Township, Yingjiang County, Yunnan Province, China. These specimens are described as a new species in this study, which also reports the first record of the genus Amblyceps in China.
[FIGURE 1 OMITTED]
Material and Methods
The specimens were fixed in 10 % formalin, and then transferred to 70 % ethanol for long-term storage. The specimens were cataloged and deposited in the collections of Yunnan University. Counts and measurements were made on the left side of specimens. Vernier calipers were used in measurements and data corrected to the nearest 0.1 mm following Ng & Lim (1995) except forehead length which follows Ng & Kottelat (1998) and adipose-fin base follows Ng & Kottelat (2000). Subunits of the head are presented as proportions of head length (%HL). Head length and measurements of body parts are presented as proportions of standard length (%SL). Anus to the vertical distance posterior margin of the pelvic-fin and anus to anal-fin origin were also measured (detailed in Fig. 1), and recorded as a percentage of the former to the latter. Teeth band, lateral line and fin rays were viewed under an Olympus MD50 anatomical lens. Photographs were made by Cannon devices 5D II. Drawings were accomplished by manual labour. Abbreviations used in this study are: SL (standard length), HL (head length), YNU (Yunnan University). Because no comparative specimens could be obtained, we quote and summarize the illustrations and data from the related literature: A. apangi, Vishwanath & Linthoingambi (2007) and Humtsoe & Bordoloi (2009); A. murraystuarti, Ng & Kottelat (2000); A. torrentis, Linthoingambi & Vishwanath (2008); A. cerinum, Ng & Wright (2010).
Amblyceps yunnanensis sp. nov. (Fig. 1)
Holotype: YNU2011082201, 75.98 mm SL; China: Yunnan Province, Yingjiang County, Nabang Township, downstream of the River Mengnai (a tributary of the upper Irrawaddy), 24[degrees]42'54.54" N, 97[degrees]34'06.44" E, 247 m, 22 August 2011, Ziming Chen.
Paratype: YNU2011082202, 61.01 mm SL; China: Yunnan Province, Yingjiang County, Nabang Township, downstream of the River Mengnai (a tributary of the upper Irrawaddy), 24[degrees]42'54.54" N, 97[degrees]34'06.44" E, 247 m, 22 August 2011, Ziming Chen.
Diagnosis: A. yunnanensis is distinguished from congeners in having the following combination of characters: skin smooth with complete lateral line, laterosensory pores haphazardly distributed in pairs; mouth sub-terminal with upper jaw slightly longer than the lower one; lips with papillae, adipose-fin short, with a low and smooth outer edge, posterior end of which rounded and separated from dorsal procurrent rays of caudal-fin by a remarkable notch; no pinnate like rays on caudal-fin rays; body depth at anus 14.1-14.6 % SL; head length 19.9-20.4 % SL; head depth 9.9-10.1 % SL; eye to nasal barbel 9.3-10.2 % SL; caudal peduncle length 19.6-19.9 % SL; caudal peduncle depth 13.5-13.6 % SL.
There were five species of Amblyceps with caudal-fins truncate and emarginate, namely, A. yunnansis, A. apangi, A. murraystuarti, A. torrentis (caudal-fin emarginated according to Linthoingambi &Vishwanath 2008) and A. cerinum with a truncate caudal-fin (vs. deeply forked and emarginated). Compared with those species, a shorter adipose-fin base (19.6-21.5 % SL) and a unique tooth band can set A. yunnansis apart immediately. It further differs from A. apangi in having a more slender caudal peduncle (caudal peduncle depth 13.5-13.6 % SL vs. 15.0-16.8 % SL); a shorter space between the eye and nasal barbel (eye to nasal barbel 9.3-10.2 % HL vs. 13.0-16.0 % HL); a less developed rictal fold (vs. large and very well developed); teeth in upper jaw with no gap (vs. with a narrow gap), from A. murraystuarti in having upper jaw slightly longer than the lower (vs. lower longer); a distinct boundary between adipose-fin and caudal procurrent rays; a longer pelvic-fin length (11.2-11.6 % SL vs. 7.4-8.8 % SL); a longer caudal-fin (length 18.1 % SL vs. 13.7-16.6 % SL), from A. torrentis in having a sub-terminal jaws (vs. equal jaws); no separation in the premaxillary teeth (vs. a narrow gap); a slightly compressed body (body depth 14.1-14.6 % SL vs. 15.3-17.3 % SL); a greater head length (19.9-20.4 % SL vs. 16.8-18.9 % SL); a shorter interorbital space (24.0-24.5 % HL vs. 29.0-37.0 % HL); a longer predorsal length (24.3-24.9 % SL vs. 20.6-22.7 % SL); a shorter caudal peduncle (caudal peduncle length 19.6-19.9 % SL vs. 21.0-24.3 % SL), from A. cerinum in having skin smooth (vs. in small granular papillae) and lateral line completed (vs. incomplete); a less depressed head (head depth 9.9-10.1 % SL vs. 7.0-9.2 % SL); a less slender tail (caudal peduncle length 19.6-19.9 % SL vs. 21.9-24.5 % SL; caudal peduncle depth 13.5-13.6 % SL vs. 9.2-11.2 % SL).
Description: Morphometric data shown in Table 1. Body elongate, covered with thick semitransparent mucus, anterior region of pelvic-fin subcylindrical, posterior region of pelvic-fin compressed gradually. Skin smooth with uniform colouration, lateral line midlateral and complete. Remarkable cup-like skin flap above the origin of the pectoral-fin, posterior to the gill-openings. Dorsal profile from lateral view, cephalic area gently convex; dorsal-fin region straight; postdorsal part from end of dorsal-fin base to end of adipose-fin base convex. Ventral profile concave from pectoral-fin to caudal-fin base; preanal area of ventral profile presenting two convexs: one from the tip of snout to the start of pelvic-fin, and the other from end of pelvic-fin to the anal-fin origin. Anus and urogenital openings located very close to depressed pelvic-fin (distance of anus to posterior margin of pelvic-fin 5.3-7.5 % of the distance to anal-fin origin) (Fig. 2).
[FIGURE 2 OMITTED]
[FIGURE 3 OMITTED]
Head depressed with cheek muscles being a little swollen residing at each side of the middle groove on the roof of head. Eyes subcutaneous, small and sub-ovoid (eye diameter 13.4-15.2 % HL). Nostrils close together, separated by a nasal barbel, the anterior naris being a complete tube-like membrane, while posterior naris being an incomplete tube whose anterior edge basally connects to nasal barbel; posterior rim of posterior narial membrane with notch. Gill openings broad, gill membranes united to each other, but free from isthmus, with 10 branchiostegal rays in each side. Oblate barbels in four pairs, extending from each side of jaws. Maxillary barbel longest, originating from end of upper and lower rictal fold of lips, extending to posterior margin of pectoral-fin base; nasal barbel extending almost to opercle; outer mandibular barbel extending to middle of pectoral-fin base; inner mandibular barbel offset from midventral line into two and outer mandibular barbel, extending to middle of pectoral-fin base.
[FIGURE 4 OMITTED]
[FIGURE 5 OMITTED]
Mouth sub-terminal, with upper jaw a little longer than the lower one, anterior rim of lower jaw not visible dorsally. Lips fleshy and slightly fimbriated, the less developed rictal fold extending to the bases of maxillary barbel on both sides; oral teeth small and villiform, premaxillary teeth in a single broad band, with a very shallow incision in the middle of the posterior edge, but no separation gap in the midline, dentary teeth in one narrow crescent band with a very narrow gap in the midline (Fig. 3).
Fins wrapped in thin skin, base of which somewhat swollen; dorsal-fin originating vertically at the middle length of pectoral-fin, with one very weak spine wrapped in very thin skin and four rays. Adipose-fin base short, in the form of low and smooth edge, originating approximately at vertical point of anterior one quarter of the length of the anal-fin base, the boundary to the caudal-fin presented by a distinct groove (Fig. 1). Anal-fin with a straight anterior margin and convex posterior rim, with 10 rays; pectoral-fin without spine, posterior margin convex, extending nearly to the level of middle of dorsal-fin, with seven rays. Pelvic-fin depressed, tip of which far for reaching the anal-fin origin, with rays seven; caudal-fin truncated without pinnate rays, dorsal procurrent rays of which extending quite anterior to its base.
Colour in living specimens: In fresh specimens: body brownish grey, dorsal and flank region of anterior 2/3 of body gray white, shade into light brown grey posterior. Area of swollen cheek muscles on dorsal surface of the head light brown, abdominal region white anteriorly and orange posteriorly. Fins with margins whitish to light yellow, dorsal-fin dark grey; anal-fin slate grey; pelvic and pectoral-fins covered by translucent light yellow membrane; adipose-fin light brown; middle of caudal-fin dark grey, and fading dorsally and ventrally. Nasal and maxillary barbels light grey to yellow. Mandibulary barbel light yellow with lighter abaxial margin.
Colour in formalin: Presence of a darker colouration, shown by grey dorsal surfaces, grey-brown profiles and yellow ventral regions. Light yellow orange laterally.
Distribution and habitat: Currently only from the River Mengnai (24[degrees]42'54.54" N, 97[degrees]34'06.44" E, 247 m), which is located near Nabang Township, Yingjiang County, in the west of Yunnan Province, China (Fig. 4). A. yunnanensis was found hiding under boulders in groups in shallow rapids of hill streams. The River Mengnai is a fast-flowing hill streams which twists its way through dense forest. The river bed has large boulders, cobbles, gravel, and sand. The wet rocks are covered with many diatoms (Fig. 5). Water temperature was 22.8 [degrees]C (at 12:40 p.m., 22 August 2011), water pH 7.0, and transparency 45 cm. Etymology: From Yunnan Province and the latin suffix "ensis", meaning from a place.
Currently, there are 19 valid species of Amblyceps, four of them (A. apangi, A. murraystuarti, A. torrentis and A. cerinum) have truncate and emarginated caudal-fins (Ng 2001, 2005, Linthoingambi & Vishwanath 2008, Ng & Wright 2010). The new species A. yunnanensis can be easily distinguished from the other species as follows. A. murraystuarti can be easily separated by having an indistinguishable posterior rim of the adipose-fin and an incomplete or absent lateral line, A. torrentis can be distinguished by its equal jaws, and a unique yellow skin in life can tell A. cerinum apart. According to Linthoingambi & Vishwanath (2008), the laterosensory pores are at the tips of short tubelike prolongations aranged longitudinally in pairs of A. torrentis, but in A. yunnanensis, the laterosensory pores are aranged irregularly (in the mixed form below: single pores anterior, long tube-like structure median, paired short tube-like structure posterior). Other comparisons of major characters between the five related species including the new species, A. yunnanensis sp. nov., A. apangi, A. murraystuarti, A. torrentis and A. cerinum are summarized in Table 2. A simple identification key is summarized below mainly on the basis of external characters of Amblyceps fishes with truncate caudal-fin.
Key to Amblyceps species with truncate caudal-fins:
1. Jaws equal ... A. torrentis
Upper jaws longer or lower longe ... 2
2. Adipose-fin largely confluent with the caudal-fin ... A. murraystuarti
Adipose-fin distinct from caudal-fin with a notch between them ... 3
3. Lateral line complete ... 4
Lateral line incomplete ... A. cerinum
4. Teeth on upper jaws separated into two halves by a gap at the midline ... A. apangi
Teeth on upper jaws continuous with no gap at the midline ... A. yunnanensis
We are very grateful to those who helped to complete and improve the manuscript: Heok Hee Ng for his kindness to give critical comments and offer related papers, Irengbam Linthoingambi for nicely providing literature. This study was supported by National Science and Technology Support Program (2013BAB06B03), the National Science Foundation of China (31272335, 30970326), China Huaneng Group Science & Technology Program (HNKJ13-H17-03), Power Construction Corporation of China Science & Technology Program: Ecological Safety Monitoring System Research in Hydroelectric Developed Watershed (DJ-ZDXM-2014-03) and 2015 Chinese Postdoctor Daily Funding W4030002 (Postdoctoral Management Committee of China and Yunnan University).
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Xiaoyan ZHANG, Yan LONG, Heng XIAO (*) and Ziming CHEN (*)
Laboratory of Conservation and Utilization of Bio-resources and Key Laboratory for Animal Genetic Diversity and Evolution of High Education in Yunnan Province, School of Life Sciences, Yunnan University, Kunming 650091, China; e-mail: email@example.com, firstname.lastname@example.org
Received 29 November 2015; Accepted 1 April 2016
* Corresponding Authors
Table 1. Morphometric data of Amblyceps yunnanensis sp. nov. (n = 2). YNU2011082201 Standard length (SL) (mm) 75.98 Head length (HL) (mm) 15.14 Percentage of standard length (%SL) Body depth at anus 14.1 Body depth at dorsal-fin origin 11.6 Predorsal length 24.9 Preanal length 63.3 Prepelvic length 49.7 Prepectoral length 17.2 Dorsal-fin base length 6.9 Anal-fin base length 14.6 Adipose-fin base length 21.5 Dorsal to adipose-fin distance 37.3 Pectoral-fin length 13.7 Pelvic-fin length 11.2 Caudal-fin length 18.1 Caudal peduncle length 19.6 Caudal peduncle depth 13.6 Head length 19.9 Percentage of head length (%HL) Head depth 49.9 Head width 78.0 Snout length 29.4 Interorbital distance 24.0 Eye diameter 6.7 Eye to nasal barbel 10.2 Nasal barbel length 63.1 Maxillary barbel length 95.0 Inner mandibular barbel length 33.2 Outer mandibular barbel length 68.7 Percentage of anus to anal-fin origin length (%) Anus to pelvic-fin ends 7.5 YNU2011082202 Mean Standard length (SL) (mm) 61.01 68.50 Head length (HL) (mm) 12.47 13.81 Percentage of standard length (%SL) Body depth at anus 14.6 14.4 Body depth at dorsal-fin origin 13.0 12.3 Predorsal length 24.3 24.6 Preanal length 66.6 65.0 Prepelvic length 47.5 48.6 Prepectoral length 17.8 17.5 Dorsal-fin base length 6.4 6.7 Anal-fin base length 14.7 14.7 Adipose-fin base length 19.6 20.6 Dorsal to adipose-fin distance 40.4 38.9 Pectoral-fin length 13.7 13.7 Pelvic-fin length 11.6 11.4 Caudal-fin length 18.1 18.1 Caudal peduncle length 19.9 19.8 Caudal peduncle depth 13.5 13.6 Head length 20.4 20.2 Percentage of head length (%HL) Head depth 49.3 49.6 Head width 75.5 76.8 Snout length 30.2 29.8 Interorbital distance 24.5 24.3 Eye diameter 7.5 7.1 Eye to nasal barbel 9.3 9.8 Nasal barbel length 53.7 58.4 Maxillary barbel length 84.2 89.6 Inner mandibular barbel length 41.9 37.6 Outer mandibular barbel length 80.3 74.5 Percentage of anus to anal-fin origin length (%) Anus to pelvic-fin ends 5.3 6.4 Table 2. Comparison of major characters between the five related species including the new species, Amblyceps yunnanensis sp. nov., A. apangi, A. murraystuarti, A. torrentis and A. cerinum. A. yunnanensis Dorsal fin rays 4 Adipose-fin Adipose-fin not confluent with the caudal-fin Anal-fin rays 10 Pectoral-fin rays 7 Pelvic-fin rays 7 Jaws Upper jaw slightly longer than the lower one Teeth on upper jaws No separation gap in the midline Lateral line Complete A. apangi(1) Dorsal fin rays 5-6 Adipose-fin Adipose-fin not confluent with the caudal-fin Anal-fin rays 7 Pectoral-fin rays 16 Pelvic-fin rays 5 Jaws Upper jaw slightly longer than the lower one Teeth on upper jaws Separated by a very narrow gap in the midline Lateral line Complete A. murraystuarti(2) Dorsal fin rays 4 Adipose-fin Adipose-fin confluent with the caudal-fin Anal-fin rays 7-8 Pectoral-fin rays 5 Pelvic-fin rays 5-6 Jaws Upper jaw slightly shorter than the lower one Teeth on upper jaws No separation gap in the midline Lateral line Incomplete A. torrentis(3) Dorsal fin rays 5 Adipose-fin Adipose-fin confluent with the caudal-fin Anal-fin rays 6-8 Pectoral-fin rays 7 Pelvic-fin rays 5 Jaws Jaws equal Teeth on upper jaws Separated by a very narrow gap in the midline Lateral line Complete A. cerinum(4) Dorsal fin rays 5-6 Adipose-fin Adipose-fin not confluent with the caudal-fin Anal-fin rays 8-9 Pectoral-fin rays 7-8 Pelvic-fin rays 5 Jaws Upper jaw longer than the lower one Teeth on upper jaws No separation gap in the midline Lateral line Incomplete (1) A. apangi: data from Humtsoe & Bordoloi (2009), (2) A. murraystuarti: data from Ng & Kottelat (2000), (3) A. torrentis: data from Linthoingambi & Vishwanath (2008), (4) A. cerinum: data from Ng & Wright (2010).
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|Author:||Zhang, Xiaoyan; Long, Yan; Xiao, Heng; Chen, Ziming|
|Date:||Jul 1, 2016|
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