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Morphological and Genetic Comparisons of Golden Crayfish, Orconectes luteus, and Rusty Crayfish, O. rusticus, with range corrections in Iowa and Minnesota

Journal of Crustacean Biology (Impact Factor: 1.02). 05/2004; 24(4):603-617. DOI: 10.1651/C-2483

ABSTRACT The distribution of the rusty crayfish, Orconectes rusticus, has been purported to include large portions of Iowa and Minnesota among many other states, whereas the golden crayfish, O. luteus, has been reported from Kansas, Arkansas, Missouri, and Illinois. Recent collections made in several river basins in Iowa and southern Minnesota and examination of museum specimens collected in Iowa revealed that many records attributed to O. rusticus are in fact O. luteus. We provide a suite of quantitative and qualitative characteristics, both morphological and genetic, that distinguish O. luteus and O. rusticus and also demonstrate that female O. luteus exhibit form alternation. Comparisons of mitochondrial 16S rRNA haplotypes among populations of O. luteus, O. rusticus, O. cf. rusticus, O. placidus, and O. virilis revealed relatively high levels of sequence divergence among taxa as well as within some taxa. We conclude that O. luteus is a native species in Iowa and southern Minnesota with introduced populations of O. rusticus occurring in both states. A more thorough survey of these states, particularly Iowa, is needed to assess the distributions of O. rusticus and O. luteus. If O. rusticus has a relatively restricted distribution in Iowa, efforts to control its anthropogenic and natural dispersal may be more effective if implemented in the near future. Our study indicates the need for more research in taxonomy, even in regions where the fauna is thought to be known well, in order for the conservation of native species and detection and management of nonindigenous species to be successful.

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    ABSTRACT: A new crayfish is described from the main channel of the lower Ohio River between Illinois and Kentucky based on examination of over 185 specimens. The new species, with gonopods of form I males typical of the subgenus Procericambarus (sensu Fitzpatrick), accounts for some of the variation previously ascribed to Orconectes placidus in Illinois. O. pardalotus is most similar to allopatric O. forceps, O. barrenensis, and O. durelli but can be distinguished from them and other species using colour in life, shape of chelae, and other characters. Colour in life can be used to diagnose O. pardalotus, and preserved specimens can be distin-guished from sympatric O. placidus and many other species by the shape of the chelae and the absence of a distomedian carpal spine on the first pereiopod of O. pardalotus (present in O. placidus) and can be distin-guished further from O. luteus using denticle arrange-ment on the chelae and structure of the gonopods of form I males. O. pardalotus is associated with rocky microhabitats at and below the summer minimum water level of the Ohio River. Notes about reproductive period and oviposition of captive specimens are provided. Zusammenfassung Beschrieben wird eine neue Flusskrebsart vom Hauptarm des unteren Ohio River zwischen Illinois und Kentucky auf der Grundlage von über 185 Exemplaren. Die Merkmale der Gonopoden bei männlichen Exem-plaren (Form I) der neuen Art, wie sie für die Untergat-tung Procericambarus (sensu Fitzpatrick) typisch sind, entsprechen teils den Variationen, die früher Orconectes placidus in Illinois zugeordnet wurden. Am meisten ähnelt O. pardalotus den allopatrischen For-men O. forceps, O. barrenensis und O. durelli, doch lässt sich die neue Art durch Lebendfärbung, Form der Scheren und weitere Merkmale unterscheiden. Die Lebendfärbung eignet sich zur raschen Bestimmung von O. pardalotus, während bei konservierten Exem-plaren die Unterscheidung zur sympatrischen Art O. placidus und vielen anderen Arten durch die Gestalt der Scheren möglich ist; außerdem fehlt bei O. pardalotus am ersten Pereiopod der distomediane Carpalstachel (bei O. placidus vorhanden); zur Unterscheidung von O. luteus dienen die Anordnung der Zähnchen an den Scheren und die Struktur der Gonopoden bei Män-nchen (Form I). Lebensraum von O. pardalotus bilden felsige Mikrohabitate unterhalb des sommerlichen Niedrigwasserspiegels im Ohio. Angefügt sind einige Bemerkungen zur Fortpflanzungszeit und Eiablage nach Beobachtungen an gefangenen Exemplaren. Résumé Est décrite une nouvelle Ecrevisse du cours principal du bas Ohio River, entre l'Illinois et le Kentucky, sur base de l'examen de plus de 185 spécimens. La nou-velle espèce, avec de gonopodes de la forme I des mâles typiques pour les sous-genre Procericambarus (sensu Fitzpatrick), rend compte de la variation autre-fois attribuée à Orconectes placidus de l'Illinois. O. pardalotus se rapproche le plus des allopatriques O. forceps, O. barrenensis et O. durelli, mais se distingue d'elles et d'autres espèces par la couleur in vivo, la forme de la chéla et d'autres caractéristiques. La couleur in vivo peut servir à diagnostiquer O. pardalo-tus et les spécimens conservés peuvent se distinguer de l'O. placidus sympatrique et de beaucout d'autres espèces par la forme de la chéla et l'absence d'une épine carpienne distomédiane sur le premiere péréiopode d'O. pardalotus (présente chez O. placidus) et peut être distinguée ensuite d'O. luteus par l'agencement des denticules sur la chéla et par la structure des gonopodes de mâles de forme I. O. pardalotus est inféodé aux microhabitats rocheux, à hauteur de et sous le niveau minimum estival de l'Ohio River. Des données sont fournies sur la période de reproduction et sur le positionnement des oeufs pour des spécimens en captivité. Sommario Una nuova specie di gambero è descritta dal canale principale del fiume Ohio inferiore tra l'Illinois e il Ken-tucky sull'esame di oltre 185 esemplari. La nuova specie, con gonopodi maschili di forma I tipici del genere Procericambarus (sensu Fitzpatrick), raccoglie alcune delle variazioni precedentemente descritte per Orconectes placidus dell'Illinois. Orconectes pardalo-tus è più simile alle specie allopatriche O. forceps, O. barrenensis, e O. durelli, ma può essere distinta da esse e da altre specie sulla base del colore in vita, della forma delle chele e di altri caratteri. La colorazione può essere usata per diagnosticare O. pardalotus e gli esemplari conservati possono essere distinti dalla specie simpatrica O. placidus e da molte altre specie per la forma delle chele e per l'assenza di una spina carpale distomediana sul primo pereiopode di O. pardalotus (presente in O. placidus) e può essere dis-tinta ulteriormente da O. luteus utilizzando la dispo-sizione dei dentelli sulle chele e la struttura dei gonopodi maschili di forma I. Orconectes pardalotus è associato a microhabitat rocciosi a livello o al di sotto del limite idrometrico estivo minimo del fiume Ohio. Vengono fornite alcune note sul periodo riproduttivo e la deposizione delle uova in specie in cattività.
    aqua, Journal of Ichthyology and Aquatic Biology. 01/2005; 10(2):57-72.

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