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Exostoma ericinum, a new glyptosternine catfish from southwestern China (Teleostei: Siluriformes: Sisoridae)
Abstract
A new species of glyptosternine catfish in the genus Exostoma is described in this study. The new species, E. ericinum, is known from the upper Dayingjiang (=Taping River) drainage in southwestern China and is distinguished from congeners in having an unique combination of the following characters: 42–44 vertebrae; parallel striae on anterolateral surfaces of lips and lower surface of maxillary barbel; interorbital distance 26–31% HL; preanal length 67.7–70.5% SL; body depth at anus 10.4–12.0% SL (1.4–1.9 times in caudal peduncle depth); length of adipose-fin base 39.5–43.0% SL; lacking an incision at posterior extremity of adipose-fin base; caudal peduncle length 23.2–26.2% SL; caudal peduncle depth 5.7–7.9% SL; and caudal-fin lobes with slightly concave posterior margin.
... The genus Exostoma Blyth, 1860 belongs to the Glyptosterninae subfamily and is known from the Brahmaputra River drainage eastwards to the Chao Phraya River drainage in northwestern Thailand (Lalramliana et al. 2015). The genus is characterized by the followings: (1) continuous post-labial groove; (2) homodont dentition consisting of distally flattened oar-shaped teeth on both jaws; (3) bilaterally separated tooth patches in upper jaw; (4) gill openings not extending to ventral surface of head; and (5) 10-11 branched pectoral-fin rays (Thomson & Page 2006 (Hora 1923), Exostoma stuarti (Hora 1923), Exostoma ericinum Ng 2018 and Exostoma sectile Ng & Kottelat 2018; and Salween drainages: Exostoma berdmorei Blyth 1860 and Exostoma gaoligongense Chen, Poly, Catania & Jiang 2017 (Blyth 1860;Hora 1923;Hora & Silas 1952;Ng & Vidthayanon 2014;Lalramliana et al. 2015;Tamang et al. 2015;Chen et al. 2017;Gong et al. 2018;Ng & Kottelat 2018;Ng 2018;Thoni & Gurung 2018;Darshan et al. 2019). Exostoma chaudhurii was considered a junior synonym of E. vinciguerrae by Norman (1925), followed by Thomson & Page (2006), Ng and Vidthayanon (2014), and others. ...
... and E. ericinum are both from the Irrawaddy basin. The other four species from the Irrawaddy basin, i.e., E. stuarti, E. chaudhurii, E. vinciguerrae, E. sectile have been described successively (Kottelat, 2013;Ng 2018;Ng & Kottelat 2018). Exostoma dulongensis sp. ...
Exostoma dulongensis sp. nov., a new species of sisorid catfish from the genus Exostoma Blyth, 1860, is described from the Xiaojiang River and Dulongjiang River, tributaries of N’mai Hka River in the Irrawaddy basin, Yunnan Province, China. Exostoma dulongensis sp. nov. is the seventeenth species reported within this genus and is most similar to Exostoma ericinum Ng 2018 in morphology but can be distinguished by the following characters: tip of pelvic fin far from anus vs. reaching when depressed; nasal barbel reaching or surpassing posterior edge of orbit vs. just reaching middle of orbit; greater preanal length (70.9%–80.1% SL vs. 67.7%–70.5%); and longer dorsal to adipose length (13.5%–23.8% SL vs. 8.0%–12.0%). The new species can also be distinguished from all known congeners by the following characters: adipose fin confluent with caudal fin and without incision; caudal fin weakly forked; 40–43 vertebrae; and pectoral fin extending to vicinity of dorsal fin origin.
... The genus Exostoma Blyth 1860-a clade of glyptosternine catfishes-can be distinguished by their having a continuous post-labial groove, flattened ventral surface of the body with horizontally patulous paired fins specified for adhesion, and distally flattened oar-shaped homodont dentition in two separated patches on both the upper and lower jaws [5,6]. Fishes of this genus generally dwell beneath the rocks in torrential streams and rivers, with a distribution range across from the Yarlung Tsangpo-Brahmaputra River drainage eastwards to the Chao Phraya River drainage in northwestern Thailand [7]. So far, a total of 20 species of Exostoma have been described and validated [8]. ...
The genus Exostoma is a group of stenotopic and rheophilic glyptosternine catfishes distributed in South and Southeast Asia. So far, comprehensive studies on mitogenomics referring to this genus are very scarce. In this study, we first sequenced and annotated the complete mito-chondrial genomes of Exostoma tibetanum and Exostoma tenuicaudatum-two sympatric congeners from the lower Yarlung Tsangpo River, Tibet, China. The mitogenomes of both species contained 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNA genes, one light-strand origin of replication, and one control region, with lengths of 16,528 bp and 16,533 bp, respectively. The mitogenome architecture, nucleotide composition, and codon usage of protein-coding genes were almost identical between the two Exostoma species, although some estimated parameters varied. Phylogenetic analysis strongly supported the monophyly of Exostoma in the subfamily Glyptos-ternae, and Exostoma tibetanum had the closest relationship to Exostoma tenuicaudatum. The divergence time estimation demonstrated that these two species diverged approximately 1.51 Ma during the early Pleistocene, which was speculated to be triggered by the river system changes caused by the uplift of the southeastern Tibetan Plateau. Selection pressure analyses indicated that all protein-coding genes of Exostoma species underwent a strong purifying selection, while minority positive sites from NADH dehydrogenase complex genes were detected. These findings are expected to promote our understanding of the molecular phylogeny of the genus Exostoma and provide valuable mitogenomic resources for the subfamily Glyptosternae.
... The material examined is deposited in the Rajiv Gandhi University Museum of Fishes (RGUMF), Doimukh, Arunachal Pradesh. The data of Exostoma sawmteai, E. gaoligongense, E. ericinum, E. mangdechhuensis and E. tibetanum were used from Lalramliana et al. (2015), Chen et al. (2017), Ng (2018), Thoni & Gurung (2018) and Gong et al. (2018) respectively; for Exostoma berdmorei, E. effrenum, and E. peregrinator from Ng and Vidthayanon (2014); and for E. sectile, E. chaudhurii, E. vinciguerrae, and E. stuarti from Ng and Kottelat (2018). ...
Exostoma kottelati, new species, is described from the Ranga River, Brahmaputra basin, in Arunachal Pradesh state, northeastern India. It differs from congeners in the Brahmaputra River basin in having a longer adipose-fin base (33.4–36.0 % SL vs. 23.4–32.9), a greater (except E. mangdechhuensis) pre-pelvic length (45.6–47.3 % SL vs. 39.3–44.6) and a greater pre-anal length (73.9–76.5 % SL vs. 62.2–70.1). It further differs from all known congeners by the following unique combination characters: the adipose fin is distinctly separated from the dorsal procurrent caudal-fin rays, pre-dorsal length 38.9–41.7% SL, adipose-fin base length 33.4–36 % SL, caudal peduncle length 18.7–21.1 % SL, caudal peduncle depth 8.8–9.5 % SL, and body depth at anus 12.5–13.5 % SL. This is the fifth species of Exostoma known from the Brahmaputra River basin.
A new species of sisorid catfish of the genus Exostoma is described from the Siang River in Arunachal Pradesh, northeastern India. The new species, Exostoma dhritiae, can be distinguished from congeners by the condition of the posterior extremity of the adipose-fin base, the degree of tuberculation on the dorsal surface of the head, and the shape of striae on the anterolateral surface of lips. Further, it is distinguished by the morphometric data for the body depth at the anus, maxillary barbel length, adipose fin base length, caudal peduncle length, caudal peduncle depth and the number of branched pectoral-fin rays. It is the twentieth reported species of Exostoma.
Exostoma tibetana, new species, is described from the lower Yarlung Tsangpo River drainage in southeastern Tibet, China. It is distinguished from congeners by having an adipose fin separate from the upper procurrent caudal-fin rays and incised at the posterior extremity of its base; the tip of the pelvic fin not reaching to the anus when adpressed; 10 branched pectoral-fin rays; and morphometric features associated with the body depth, adipose-fin base length, caudal-peduncle depth, snout length, and eye diameter. The validity of this new species was also supported by molecular phylogenetic analysis based on Cyt b gene sequences.
We review members of the sisorid catfish genus Exostoma known from Thailand. Three species are recognized, of which two from the headwaters of the Chao Phraya River drainage in northwestern Thailand, are described here as new: E. effrenum and E. peregrinator. In addition to the two new species, E. berdmorei (which is here redescribed) is also known from the Salween River drainage in western Thailand. The three species can be distinguished from each other and other congeners by the morphologies of the adipose and caudal fins, as well as morphometric data for the eye diameter, head width, dorsal-to-adipose distance, body depth at anus, caudal-peduncle length, caudal-peduncle depth, and numbers of branched pectoral-fin rays and preanal vertebrae.
A new species of sisorid catfish in the genus Exostoma is described from the upper Irrawaddy River drainage in northern Myanmar. The new species can be distinguished from congeners by the condition of the posterior extremity of the adipose-fin base, the degree of tuberculation in the preorbital area, as well as morphometric data for the nasal barbel length, snout length, interorbital distance, adipose fin-base length, body depth at anus, caudal-peduncle length, and caudal-peduncle depth. The taxonomic status of congeners in the Irrawaddy River drainage is also discussed, and E. chaudhurii is revalidated as a distinct species.
Glyptosternines are highly specialized sisorid catfishes with greatly depressed body profiles; enlarged, horizontally extended paired fins, modified for adhesion, typically inhabiting torrential waters in rocky mountain streams and rivers. Their range of distribution extends from the upper reaches of the Amu Darya River drainage in Turkmenistan southwards and eastwards to Indochina and the Yangtze River (Changjiang) drainage of central China, and the Mekong and Salween drainages in northern and western Thailand (Vidthayanon et al. 2009; Ng & Vidthayanon 2014).
The results of a phylogenetic analysis of the Asian catfish family Sisoridae are presented in this study. The phylogenetic relationships of 106 (out of the 246) species of sisorid catfishes (representing over 40 % of the species diversity) were elucidated utilizing 197 morphological characters. Although a parsimony analysis failed to fully resolve the relationships of the 106 species in this study, nearly all of the genera analyzed (20 out of 22, with the exception of Ayarnangra and Erethistes) were recognized as natural; diagnoses for all 23 sisorid genera are provided. Novel generic interrelationships within the family were also recovered in this study. Two clades within the Sisoridae were recovered (Glyptosterninae and Sisorinae), with the Sisorinae being recovered as composed of three subclades (Bagariini, Erethistini and Sisorini). Diagnoses for these clades are provided, and aspects of the phylogeny in relation to the historical biogeography, as well as the evolution of body size and the thoracic adhesive apparatus in the group are also discussed.
Exostoma sawmteai, new species, is described from the Barak River drainage in Mizoram State, northeastern India. It differs from congeners in having the posterior end of the adipose fin adnate with dorsal procurrent caudal-fin rays, a lunate caudal fin, total number of vertebrae, and morphometric features associated with the snout, eye, distance between the paired fins, body depth, adipose-fin base, and caudal peduncle. Evidence from the literature suggests that the genus is more diverse in the Indian subcontinent than currently recognized.
Ecological opportunities and physical challenges of fast-water habitats have dramatically shaped the evolution of freshwater fish lineages from a broad diversity of clades globally, often leading to the convergent or parallel evolution of highly similar morphologies. In this chapter, we present a patch dynamics model of how longitudinal shifts in geomorphological and ecological processes from small headwater torrents to large river rapids may differentially affect gene flow among, and evolutionary specialization within, resident rheophilic fish populations. Fast-water habitats offer ecological advantages including predator avoidance and increased foraging efficiency, but require that organisms resist downstream displacement and avoid shifting, crushing substrates. We review the specialized morphological and behavioral characteristics associated with life in fast waters and the taxonomic distribution of these specializations across fishes. We also report results of specific functional studies where available and summarize empirical evolutionary, phylogenetic support for our model and for specific mechanisms or pathways by which rheophilic specializations may arise.
A new sisorid catfish, Exostoma barakensis is described from the Iyei River (Barak drainage) of Manipur, India. It is distinguished from E. berdmorei in having deeper body, its depth 15.6 (14.0-16.5) vs. 10.9 % SL; less numbers of anal fin rays ii, 4 1/2 -5 vs. i, 6; broadly rounded vs. pointed snout; emarginated vs. deeply forked caudal fin. It differs from E. labiatum in having deeper caudal peduncle, its height 49.8 (44.1-56.7) vs. 31.2-38.7 % caudal peduncle length; interdorsal space present vs. absent; less number of pectoral fin rays i, 10-11 vs. i, 12-13; caudal emarginated vs. forked. It differs from E. vinciguerrae in having wider head, its width 88.9 (85.2-91.6) vs.105.1 (105-108) % HL; smaller eye, its diameter 9.6 (7.3-11.6) vs.16.2 (16.0-16.4) % HL. It also differs from E. stuarti in having shallower body, its depth 15.8 (14.2-16.9) vs. 18.1 % SL; longer snout, its length 59.5 (58.1-61.5) vs. 47.6 % HL; larger eye, its diameter 9.6 (7.3-11.6) vs. 4.7 % HL; deeper caudal peduncle, its height 49.8 (44.1-56.7) vs. 42.8 % caudal peduncle length. Exostoma vinciguerrae and E. stuarti that synonymised under E. labiatum have been examined and found to have distinguishable differences from E. labiatum, and therefore have been resurrected as valid species.
49.4 m SL; China: Yunnan Province, Nujiang Prefecture
E. gaoligongense: CAS 223554 (1), 49.4 m SL; China: Yunnan Province, Nujiang Prefecture, Lushui County,
Xiaojiang at Gangfang, near Myanmar border, 26°8'N 98°36'E. Additional data from Chen et al. (2017).
A new species of sisorid catfish of the genus Exostoma from the Salween drainage
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Salween drainage, Yunnan, China. Zoological Research, 38 (5), 291-299.
https://doi.org/10.24272/j.issn.2095-8137.2017.065
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Thailand and Cambodia. Ichthyological Exploration of Freshwaters, 5 (3), 241-256.
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0 mm SL; Thailand: Mae Hong Son Province, Mae Sariang District, Huay Po. NIFI 1669 (1), 66.4 mm SL; Tak Province, Tha Song Yang District
- E Berdmorei
E. berdmorei: NIFI 0894 (2), 34.3-54.0 mm SL; Thailand: Mae Hong Son Province, Mae Sariang District, Huay
Po. NIFI 1669 (1), 66.4 mm SL; Tak Province, Tha Song Yang District, Mae Jawang. ZRC 54293 (1), 53.4 mm
SL; Thailand: Mae Hong Son Province, left side tributary of Mae Nam Pai, about 14 km N of Mae Sariang at
bridge with road 108.
80.2 mm SL; Myanmar: Kachin State, Imawbum Range, Harmaw Chaung, eastern part of Tsaw Law village, northern part of Satt Chaung village and Chaung Lunn village, tributary of May Hka
- E Chaudhurii
E. chaudhurii: ZSI F9741/1, holotype, 53.9 mm SL; Myanmar: Kachin State: Putao Plains. CMK 26233 (1), 80.2
mm SL; Myanmar: Kachin State, Imawbum Range, Harmaw Chaung, eastern part of Tsaw Law village,
northern part of Satt Chaung village and Chaung Lunn village, tributary of May Hka, 26°13'15"N 98°20'7"E.
CMK 26291 (29), 34.6-89.3 mm SL; Myanmar: Kachin State, Hponganrazi Wildlife Sanctuary, area of Ziyar
Dam, Monlan Chaung, 27°33'53"N 97°5'22"E.
3 mm SL; NIFI 3765 (2 paratypes), 51.6-65.0 mm SL; UMMZ 250050 (1 paratype), 54.2 mm SL; Thailand: Mae Hong Son Province, Mae La Noi District, Ping Noi stream close to Doi Om Phai in Chiang Mai Province
- E Effrenum
E. effrenum: NIFI 4955 (holotype), 51.3 mm SL; NIFI 3765 (2 paratypes), 51.6-65.0 mm SL; UMMZ 250050 (1
paratype), 54.2 mm SL; Thailand: Mae Hong Son Province, Mae La Noi District, Ping Noi stream close to Doi
Om Phai in Chiang Mai Province, 18°23'43"N 98°7'56"E.
70.2 mm SL; NIFI 3762 (4 paratypes), 45.6-65.6 mm SL
- E Peregrinator
E. peregrinator: NIFI 3831 (holotype), 70.2 mm SL; NIFI 3762 (4 paratypes), 45.6-65.6 mm SL; NIFI 3764 (8
paratypes), 23.3-67.4 mm SL; UMMZ 250051 (6 paratypes), 26.2-65.1 mm SL;Thailand: Mae Hong Son
Province, Mae La Noi District, Ban Tun, 18°18'31"N 98°8'37"E.
3 mm SL; PUCMF 14012 (13 paratypes), 52.1-84.9 mm SL; India: Mizoram: Champhai District, Pharsih River, a tributary of Tuivai River (Barak River drainage) in the vicinity of Kawlbem
- E Sawmteai
E. sawmteai: PUCMF 14011 (holotype), 79.3 mm SL; PUCMF 14012 (13 paratypes), 52.1-84.9 mm SL; India:
Mizoram: Champhai District, Pharsih River, a tributary of Tuivai River (Barak River drainage) in the vicinity
of Kawlbem, 23°51'58"N 93°17'20"E.