Barbus sensitivus, a new species with extensive pitlines from the Sanaga River (Teleostei: Cyprinidae)
Tyson R. Roberts
aqua, International Journal of Ichthyology, pp. 187-196, Volume 16, Issue 4 – 15 October 2010
Barbus sensitivus new species, from the Sanaga River in Cameroon, West Africa, has a much more slender caudal peduncle than any other small African barb. It also has extensively distributed exposed pitline organelles in pit lines on the head and scales, illustrated here by scanning electron micrographs. Similar pit lines and pitline organelles evidently occur in various other Old World barbs assigned to various genera in Africa and Asia but adequate comparative studies including SEM observations are not available to permit their comparison and identification. None of the species previously described are very similar to this new species. The pitline organelles of B. sensitivus n. sp. have exposed or free neuromasts. Their sensory modality presumably is mechanosensory. Extensively distributed in large pit lines on the head and body of adult B. sensitivus n. sp., they are similar to lateral line neuromast organs in advanced larvae of Cyprinus carpio, Gnathopogon elongatus caerulescens, and Danio rerio. They are most concentrated on the ventrolateral part of the head, which has about 3000 of them, most bearing 20 to 100 kinocilia up to 7 micra long and 0.4 micra in diameter. Pit lines with smaller pitline organelles and fewer kinocilia occur in rows on the scales of the body and on the dorsal surface of the head but are absent from the fins. Their presence in adult B. sensitivus new species might represent a neotenic retention. In larval Gnathopogon elongatus caerulescens they facilitate detection of tiny planktonic prey such as Artemia when feeding under reduced light conditions.
APPELBAUM, S. & RIEHL, R. 1997. Scanning electron microscopic observations of the chemo and mechanoreceptors of carp larvae (Cyprinus carpio) and their relationship to early behavior. Aquatic Living Resouces 10: 1-12.
BARNARD, K. H. 1948. Report on a collection of fishes from the Okavango River, with notes on Zambesi fishes. Annals of the South African Museum 36 (5): 407-458.
BLEEKER, P. 1863. Mémoire sur les poissons de la côte deGuinée. Natuurkundige Verhandelingen van de Hollandsche Maatschappij der Wetenschappen te Haarlem (Ser. 2) 18: 1-136, pls 1-28.
BÖHLKE, E. B. 1984. Catalogue of the type specimens in the ichthyological collections of the Academy of Natural Sciences of Philadelphia. Academy of Natural Sciences of Philadelphia Special Publication 14, viii+246 pp.
BOULENGER, G. A. 1911. Catalogue of the Freshwater Fishes of Africa in the British Museum (Natural History). London. Volume 2: i-xii + 1-529.
COPE, E. D. 1869. Supplement on some new species of American and African fishes. Transactions of the American Philosophical Society 13 (2): 400-407.
DAGET, J., GOSSE, J. P. & THYS VAN DEN AUDENAERDE, D. F. E. (Eds). 1984. Check-list of the freshwater fishes of Africa. ORSTOM-MRAC., vol. 1, xviii+410 pp.
DEJEN, E., RUTJES, H. A., DE GRAAF, M., NAGELKERKE, L. A. J., OSSE, J. W. M. & SIBBING, F. A. 2002. The ‘small barbs’ Barbus humilis and B. trispilopleura of Lake Tana (Ethiopia): are they ecotypes of the same species? Environmental Biology of Fishes 65 (4): 373-386.
DU CHAILLU, P. B. 1861. Explorations and Adventures in Equatorial Africa. New York, Harper and Brothers, 531 pp., map.
DU CHAILLU, P. B. 1867. A Journey to Ashango-Land: and Further Penetration into Equatorial Africa. New York, D. Appleton and Co., xxiv+501 pp., map.
ESCHMEYER, W. N. 2010. Catalog of Fishes. California Academy of Sciences (online; last revised 6 May 2010).
GREENWOOD, P. H. 1962. A revision of certain Barbus (Pisces, Cyprinidae) from East, Central, and South Africa. Bulletin of the British Museum (Natural History) 8 (4): 153-208.
GREENWOOD, P. H. 1970. A revision of the cyprinid species Barbus (Enteromius) radiatus Peters, 1853, with a note on the synonymy of the subgenera Beirabarbus and Enteromius. Revue de Zoologie et Botanique africaine 82 (1-2): 1-12.
HERRE, A. W. C. T. 1936. A new cyprinid genus and species and a new characin from Portuguese East Africa. Proceedings of the Biological Society of Washington 49: 99-101.
KARAMAN, M. S. 1971. Süsswasserfische der Turkei. 8. Teil. Revision der Barben Europas, Vorderasiens und Nordafrikas. Mittheilungen Hamburgischen Museum und Institute 67: 175-254.
LOISELLE, P. V. 1973. Description of a new species of Barbus (Pisces Cyprinidae) from West Africa. Revue de Zoologie et de Botanique Africaines 87 (2): 379-390.
LOISELLE, P. V. & WELCOMME, R. L. 1971. Two new species of Barbus (Pisces: Cyprinidae) from southeastern Dahomey. Revue de Zoologie et de Botanique Africaines 83 (1-2): 1-15.
MUKAI, Y., YOSHIKAWA, H. & KOBAYASHI, H. 1994. The relationship between the length of the cupulae of free neuromasts and feeding ability in larvae of the willow shiner Gnathopogon elngatus caerulescens (Teleostei, Cyprinidae). Journal of Experimental Biology 197: 399-403.
MUKAI, Y. & KOBAYASHI, H. 1995. Development of free neuromasts with special reference to sensory polarity in larvae of the willow shiner, Gnathopogon elongatus caerulescens (Teleostei, Cyprinidae). Zoological Science 12: 125-131.
MUKAI, Y. 2006. Role of free neuromasts in larval feeding of willow shiner Gnathopogon elongatus caerulescens Teleostei, Cyprinidae. Fisheries Science 72 (4): 705-709.
STEWART, D. J. 1977. Geographic variation of Barbus radiatus Peters, a widely distributed African cyprinid fish. Environmental Biology of Fishes 1 (2): 113-125.
TWEDDLE, D., BALIRWA, J., MACLENNAN, D., OKARONON, J., TUMWEBAZE, R., GETABU, A. & BASSA, S. 2006. Occurrence of Barbus profundus Greenwood 1970 (Telostei: Cyprinidae) in mid-water in Lake Victoria. African Journal of Aquatic Science 31 (1): 155-157
WEBB, J. F. & SHIREY, J. E.. 2003. Postembryonic development of the cranial lateral line canals and neuromasts in zebrafish. Developmental Dynamics 228: 370-385.