Exostoma

Taxobox
name = "Exostoma"
regnum = Animalia
phylum = Chordata
classis = Actinopterygii
ordo = Siluriformes
familia = Sisoridae
subfamilia = Glyptosterninae
tribus = Glyptosternina
genus = "Exostoma"
genus_authority = Blyth, 1860
type_species = "Exostoma berdmorei"
type_species_authority = Blyth, 1860
subdivision_ranks = Binomial name
subdivision =
"Exostoma berdmorei"
Blyth, 1860
"Exostoma labiatum"
(McClelland, 1842)
"Exostoma stuarti"
(Hora, 1923)
"Exostoma vinciguerrae"
(Regan, 1905)

"Exostoma" is a genus of catfishes (order Siluriformes) of the family Sisoridae. It includes four species that "E. berdmorei", "E. labiatum", "E. stuarti", and "E. vinciguerrae".cite journal|url=http://www.mapress.com/zootaxa/2006f/zt01345p096.pdf|title=Genera of the Asian Catfish Families Sisoridae and Erethistidae (Teleostei: Siluriformes)|first=Alfred W.|last=Thomson|coauthors=Page, Lawrence M.|journal=Zootaxa|volume=1345|pages=1–96|year=2006|format=PDF]

Taxonomy

In a 2007 checklist of sisorid and erethistid catfishes, Thomson lists "E. stuarti" and "E. vinciguerrae" as valid species. In a 2007 checklist of catfishes, Ferraris lists these two species as species inquerendae, noting that these species are either treated as valid or as synonyms of "E. labiatum".cite journal|url=http://silurus.acnatsci.org/ACSI/library/biblios/2007_Ferraris_Catfish_Checklist.pdf|title=Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types|first=Carl J., Jr.|last=Ferraris|journal=Zootaxa|volume=1418|pages=1–628|year=2007|format=PDF]

Distribution and habitat

"Exostoma" species are distributed in the Brahmaputra drainage of northeast India, and east and south to the Salween drainages in Burma. "E. berdmorei" is found in the Sittang and Salween drainages in Burma. "E. labiatum" is known from the Brahmaputra drainage in northeast India, but has also been recorded in the Salween drainage in Burma, the Ayeyarwady drainage in China, and the Brahmaputra drainage in Tibet and Burma. "E. stuarti" is from the Ayeyarwady River of Burma and India; however, it has not been collected since its original discovery.

"E. labiatum" is found in mountain rapids.

Description

"Exostoma" is distinguished by having a continuous groove behind the lips (post-labial groove), the gill openings not extending onto the underside (venter), homodont dentition of oar-shaped, distally flattened teeth in both jaws, the tooth patches separated in upper jaw, and 10–11 branched pectoral rays. The head is depressed with a broadly rounded snout. The body is elongate and flattened ventrally to the pelvic fins. The eyes are minute, dorsally located, and under the skin (subcutaenous). The lips are thick, fleshy, and papillated. The teeth are small to large, moveable, oar-shaped, flattened distally and directed posteriorly in distinct patches.

"E. stuarti" is recorded to grow to 5.6 centimetres (2.2 in) SL.FishBase species|genus=Exostoma|species=stuarti|year=2007|month=July] "E. berdmorei" and "E. labiatum" grow to about 10–11 cm (3.94–4.33 in) TL.FishBase species|genus=Exostoma|species=berdmorei|year=2007|month=July] FishBase species|genus=Exostoma|species=labiatum|year=2007|month=July]

References