Neuer Killifsch: Laimosemion ubim

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Neuer Killifsch: Laimosemion ubim

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Laimosemion ubim, a new miniature killifish from the Brazilian Amazon (Teleostei: Rivulidae)

Wilson J. E. M. Costa and Henrique Lazzarotto

Ichthyol. Explor. Freshwaters, Vol. 24, No. 4, pp. 371-378, 3 figs., 1 tab., April 2014


Abstract
Laimosemion ubim, new species, is described from a small stream tributary of Lago Amanã system, Central Amazon, northern Brazil, based on external and internal anatomical morphological characters. It is considered closely related to other species of Laimosemion, subgenus Owiyeye, from the same region. It is distinguished from all other rivulids by having double-branched epipleural ribs, a condition never found among cyprinodontiforms, and from all its congeners by having hypertrophied teeth on the anterior portion of the outer row of the premaxilla and dentary in males. It reaches a maximum adult size of about 18 mm SL and exhibits several reductive characters, as expected for a miniature species, including a notable reductive character state – four branchiostegal rays. Introduction Evolutionary events of miniaturization, consisting of extreme reduction in body size within a lineage (Hanken & Wake, 1993), are a common phenomenon among freshwater teleost fishes in tropical regions of the world (e. g., Weitzman & Vari, 1988; Kottelat & Vidthayanon, 1993; Costa & Le Bail, 1999). Early fish collectors and taxonomists neglected miniature fish species in their samples and studies, as reported by Weitzman & Vari (1988) and Costa & Le Bail (1999), but as a result of collections directed to more specialized habitats and use of appropriated collecting techniques, * new reports about miniature freshwater fishes (i. e., maturing at sizes under 20 mm SL, or reaching 26.0 mm SL as maximum adult size, as established by Weitzman & Vari (1988), have became frequent in the literature (Mattos et al., 2013). A great part of reported miniaturization events in freshwater fishes involves species inhabiting swampy forests with acidic waters (e. g., Costa, 1998; Britz & Kottelat, 2003; Kottelat et al., 2006; Conway et al., 2011; Britz et al., 2012). Among Amazonian killifishes found in that habitat, cases of miniaturization are known in the poeciliid genus Fluviphylax and in the rivulid genera Laimosemion, Melanorivulus, Plesiolebias and Spec

http://www.pfeil-verlag.de/04biol/pdf/ief24_4_07.pdf
Laimosemion ubim male.JPG
Laimosemion ubim male.JPG (30.43 KiB) 1292 mal betrachtet
Laimosemion ubim female.JPG
Laimosemion ubim female.JPG (36.26 KiB) 1280 mal betrachtet
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