Etnier, David A.

Robison, Henry W.

UARK (University of Arkansas )

Journal of the Arkansas Academy of Science Volume 58 Article 19 2004 Unusual Hybognathus (Osteichthyes, Cyprinidae) from Lower White River, Arkansas David A. Etnier University of Tennessee Henry W. Robison Southern Arkansas University Follow this and additional works at: https://scholarworks.uark.edu/jaas  Part of the Zoology Commons Recommended Citation Etnier, David A. and Robison, Henry W. (2004) "Unusual Hybognathus (Osteichthyes, Cyprinidae) from Lower White River, Arkansas," Journal of the Arkansas Academy of Science: Vol. 58 , Article 19. Available at: https://scholarworks.uark.edu/jaas/vol58/iss1/19 This article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able to read, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking prior permission from the publisher or the author. This General Note is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu. 109GENERAL NOTESAn Unusual Hybognathus (Osteichthyes, Cyprinidae)from Lower White River, ArkansasDavid A.EtnierDepartment of Ecology and Evolutionary BiologyUniversity of TennesseeKnoxville,TN 37996-1610*Corresponding AuthorThe cyprinid genus, Hybognathus, is currently treated ascontaining seven species (Schmidt, 1994) of which threehave been documented to occur in Arkansas, namely,Hybognathus nuchalis (Mississippi silvery minnow), H.placitus(Plains minnow), and H. hayi (cypress minnow) (Robisonand Buchanan, 1988). A fourth species, Hybognathus argyritis(western silvery minnow), known from neighboringMissouri, but not heretofore collected from Arkansas, is thefocus of this paper.Hybognathus nuchalis, H. argyritis, and H. placitusconstitute a close-knit group having recent distributionalrelationships that seem to reflect their distributions inpreglacial times (Pflieger, 1971). H.nuchalis is widespread inthe central Mississippi Valley whereas H. argyritus has itsdistributional center in the upper Missouri River system,and H.placitus is widespread inthe central and plains states.Pfleiger (1971) resurrected the name Hybognathus argyritisGirard for the form in the Missouri River system, and herestricted the name H. nuchalis Agassiz to the form in thecentral Mississippi Valley.On 17 October 2003 a University ofTennessee Regionalraunas class collected and preserved 45 Hybognathuspecimens from river miles 14-15, lower White River,Desha/Arkansas county line, Arkansas. One of these (39mm SL) has a basioccipital process characteristic of H.argyritis, a species not known from Arkansas (Robison andJuchanan, 1988). It was entered into the University ofTennessee Research Collection of Fishes (UT) as H argyritisUT 44.10001). Etnier noted at the time that its eye did noteem appreciably smaller than that ofa 41 mm SL specimenof H. nuchalis from the same collection (UT 44.10002, 44pecimens, 41-75 mm SL). A more careful examination ofhe "//. argyritis''' specimen indicated that its eye was evenarger (3.2 mm) than that of the 41mm SL H. nuchalis fromUT 44.10002 (3.0 mm). Comparison witha 40 mm SL H.argyritis (UT 44.7179) fromMissouri River Mile 16.4 made itclear (eye diameter 2.1 mm) that we did not have a typicalspecimen of H.argyritis.tTwo characters serve to best separate H.nuchalis from H.rgyritis - the shape of the basioccipital process and the sizeHenry W. Robison*Department of BiologySouthern Arkansas UniversityMagnolia, AR 71754-9354of the eye. Pflieger (1971) stated that the only trulydiagnostic character for separating H. nuchalis and H.argyritis is the shape of the basioccipital process. In H.nuchalis, the basioccipital is greatly expanded posteriorly,and the posterior margin is deeply emarginate (Niazi andMoore, 1962; Fig. 21). The process in H. argyritis is lessexpanded posteriorly, and the posterior margin is truncateor only shallowly emarginate (Etnier and Starnes, 1993; Fig.82). In H.placitus the basioccipital process is narrow andpeg-like with the muscles nearly touching at the point ofattachment to the process whereas the process itself is broadand blade-like with muscles well-separated at the point ofattachment to the basioccipital process inH. nuchalis and H.argyritis (Pflieger, 1997).Eye length is greater in H. nuchalis than in H. argyritis.In H. nuchalis the eye diameter is greater than the width ofthe mouth opening whereas in H. argyritis the eye diameteris less than the mouth opening. In H. argyritis the headlength is 4-4.8 times the eye diameter whereas inH. nuchalisthe eye is slightly larger, and head length is only 3.6-4.2times the eye diameter.Possible identifications of this lower White Riverspecimen are (1) a southern "race" of//, argyritis with a largeeye; (2) a hybrid between H.placitus and H. nuchalis; (3) ahybrid between H. nuchalis and some other cyprinid; (4) amisidentification of a non-Hybognathus minnow; (5) ariverine waif of H. hayi, a species associated with cypressswamps; (6) mere within population variation inbasioccipital shape inH. nuchalis; or (7) an unknown speciesof Hybognathus. Possibility (2) seems unlikely, as H.placitusis known from only extreme western Arkansas and has anextremely small eye; (3) and (4) seem unlikely as the coiledgut, black peritoneum, and pharyngeal tooth count andshape are typical for Hybognathus, and the specimen isdefinitely not Notropis nubilus; (5) a 39 mm SL H.hayi fromthe Hatchie River system, TN, has a much more terminalmouth and more broad basioccipital process (1.1 mm vs. 0.6mm); and (6) we examined the basioccipital process ofall44specimens inUT 44.10002 and from hundreds of additionalHybognathus collected in the lower Mississippi River andhave not noted visible variation. The most likelypossibilities are thus a large-eyed southern race of H.argyritis or an unknown species. Since a dam is alreadyJournal of the Arkansas Academy of Science, Vol. 58, 2004109Journal of the Arkansas Academy of Science, Vol. 58 [2004], Art. 19Published by Arkansas Academy of Science, 2004An Unusual Hybognathus (Osteichthyes, Cyprinidae) from Lower White River, Arkansas110under construction at White River mile 0.5, efforts shouldbe made to secure additional specimens in the lower Whiteand Arkansas rivers and adjacent Mississippi River.Literature CitedEtnier, D. A., and W. C. Starnes. 1993. The fishes ofTennessee. Univ.Tennessee Press, Knoxville,TN. 689 pp.Niazi, A. D., and G. A. Moore. 1962. The weberianapparatus of Hybognathus placitus and H. nuchalis(Cyprinidae). Southwest. Nat. 7:41-50.Pflieger, W. L. 1971. A distributional study of Missourifishes. Univ.Kansas Mus. Nat. Hist,Publ. 20:225-570.Pflieger, W. L. 1997. Fishes ofMissouri. 2nd.ed. MissouriDept. Conservation, Jefferson City,MO. 372 pp.Robison, H. W., and T. M. Buchanan. 1988. Fishes ofArkansas. Univ. Arkansas Press, Fayetteville, AR. 536 pp.Schmidt, T. R. 1994. Phylogenetic relationships of thegenus Hybognathus (Teleostei: Cyprinidae). Copeia1994:622-630Journal of the Arkansas Academy of Science, Vol 58, 2004110Journal of the Arkansas Academy of Science, Vol. 58 [2004], Art. 19https://scholarworks.uark.edu/jaas/vol58/iss1/19

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Unusual Hybognathus (Osteichthyes, Cyprinidae) from Lower White River, Arkansas

ScholarWorks@UARK

Journal of the Arkansas Academy of ScienceVolume 58 Article 192004Unusual Hybognathus (Osteichthyes, Cyprinidae)from Lower White River, ArkansasDavid A. EtnierUniversity of TennesseeHenry W. RobisonSouthern Arkansas UniversityFollow this and additional works at: http://scholarworks.uark.edu/jaasPart of the Zoology CommonsThis article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able toread, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking priorpermission from the publisher or the author.This General Note is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the ArkansasAcademy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu.Recommended CitationEtnier, David A. and Robison, Henry W. (2004) "Unusual Hybognathus (Osteichthyes, Cyprinidae) from Lower White River,Arkansas," Journal of the Arkansas Academy of Science: Vol. 58 , Article 19.Available at: http://scholarworks.uark.edu/jaas/vol58/iss1/19109GENERAL NOTESAn Unusual Hybognathus (Osteichthyes, Cyprinidae)from Lower White River, ArkansasDavid A.EtnierDepartment of Ecology and Evolutionary BiologyUniversity of TennesseeKnoxville,TN 37996-1610*Corresponding AuthorThe cyprinid genus, Hybognathus, is currently treated ascontaining seven species (Schmidt, 1994) of which threehave been documented to occur in Arkansas, namely,Hybognathus nuchalis (Mississippi silvery minnow), H.placitus(Plains minnow), and H. hayi (cypress minnow) (Robisonand Buchanan, 1988). A fourth species, Hybognathus argyritis(western silvery minnow), known from neighboringMissouri, but not heretofore collected from Arkansas, is thefocus of this paper.Hybognathus nuchalis, H. argyritis, and H. placitusconstitute a close-knit group having recent distributionalrelationships that seem to reflect their distributions inpreglacial times (Pflieger, 1971). H.nuchalis is widespread inthe central Mississippi Valley whereas H. argyritus has itsdistributional center in the upper Missouri River system,and H.placitus is widespread inthe central and plains states.Pfleiger (1971) resurrected the name Hybognathus argyritisGirard for the form in the Missouri River system, and herestricted the name H. nuchalis Agassiz to the form in thecentral Mississippi Valley.On 17 October 2003 a University ofTennessee Regionalraunas class collected and preserved 45 Hybognathuspecimens from river miles 14-15, lower White River,Desha/Arkansas county line, Arkansas. One of these (39mm SL) has a basioccipital process characteristic of H.argyritis, a species not known from Arkansas (Robison andJuchanan, 1988). It was entered into the University ofTennessee Research Collection of Fishes (UT) as H argyritisUT 44.10001). Etnier noted at the time that its eye did noteem appreciably smaller than that ofa 41 mm SL specimenof H. nuchalis from the same collection (UT 44.10002, 44pecimens, 41-75 mm SL). A more careful examination ofhe "//. argyritis''' specimen indicated that its eye was evenarger (3.2 mm) than that of the 41mm SL H. nuchalis fromUT 44.10002 (3.0 mm). Comparison witha 40 mm SL H.argyritis (UT 44.7179) fromMissouri River Mile 16.4 made itclear (eye diameter 2.1 mm) that we did not have a typicalspecimen of H.argyritis.tTwo characters serve to best separate H.nuchalis from H.rgyritis - the shape of the basioccipital process and the sizeHenry W. Robison*Department of BiologySouthern Arkansas UniversityMagnolia, AR 71754-9354of the eye. Pflieger (1971) stated that the only trulydiagnostic character for separating H. nuchalis and H.argyritis is the shape of the basioccipital process. In H.nuchalis, the basioccipital is greatly expanded posteriorly,and the posterior margin is deeply emarginate (Niazi andMoore, 1962; Fig. 21). The process in H. argyritis is lessexpanded posteriorly, and the posterior margin is truncateor only shallowly emarginate (Etnier and Starnes, 1993; Fig.82). In H.placitus the basioccipital process is narrow andpeg-like with the muscles nearly touching at the point ofattachment to the process whereas the process itself is broadand blade-like with muscles well-separated at the point ofattachment to the basioccipital process inH. nuchalis and H.argyritis (Pflieger, 1997).Eye length is greater in H. nuchalis than in H. argyritis.In H. nuchalis the eye diameter is greater than the width ofthe mouth opening whereas in H. argyritis the eye diameteris less than the mouth opening. In H. argyritis the headlength is 4-4.8 times the eye diameter whereas inH. nuchalisthe eye is slightly larger, and head length is only 3.6-4.2times the eye diameter.Possible identifications of this lower White Riverspecimen are (1) a southern "race" of//, argyritis with a largeeye; (2) a hybrid between H.placitus and H. nuchalis; (3) ahybrid between H. nuchalis and some other cyprinid; (4) amisidentification of a non-Hybognathus minnow; (5) ariverine waif of H. hayi, a species associated with cypressswamps; (6) mere within population variation inbasioccipital shape inH. nuchalis; or (7) an unknown speciesof Hybognathus. Possibility (2) seems unlikely, as H.placitusis known from only extreme western Arkansas and has anextremely small eye; (3) and (4) seem unlikely as the coiledgut, black peritoneum, and pharyngeal tooth count andshape are typical for Hybognathus, and the specimen isdefinitely not Notropis nubilus; (5) a 39 mm SL H.hayi fromthe Hatchie River system, TN, has a much more terminalmouth and more broad basioccipital process (1.1 mm vs. 0.6mm); and (6) we examined the basioccipital process ofall44specimens inUT 44.10002 and from hundreds of additionalHybognathus collected in the lower Mississippi River andhave not noted visible variation. The most likelypossibilities are thus a large-eyed southern race of H.argyritis or an unknown species. Since a dam is alreadyJournal of the Arkansas Academy of Science, Vol. 58, 2004109Journal of the Arkansas Academy of Science, Vol. 58 [2004], Art. 19Published by Arkansas Academy of Science, 2004An Unusual Hybognathus (Osteichthyes, Cyprinidae) from Lower White River, Arkansas110under construction at White River mile 0.5, efforts shouldbe made to secure additional specimens in the lower Whiteand Arkansas rivers and adjacent Mississippi River.Literature CitedEtnier, D. A., and W. C. Starnes. 1993. The fishes ofTennessee. Univ.Tennessee Press, Knoxville,TN. 689 pp.Niazi, A. D., and G. A. Moore. 1962. The weberianapparatus of Hybognathus placitus and H. nuchalis(Cyprinidae). Southwest. Nat. 7:41-50.Pflieger, W. L. 1971. A distributional study of Missourifishes. Univ.Kansas Mus. Nat. Hist,Publ. 20:225-570.Pflieger, W. L. 1997. Fishes ofMissouri. 2nd.ed. MissouriDept. Conservation, Jefferson City,MO. 372 pp.Robison, H. W., and T. M. Buchanan. 1988. Fishes ofArkansas. Univ. Arkansas Press, Fayetteville, AR. 536 pp.Schmidt, T. R. 1994. Phylogenetic relationships of thegenus Hybognathus (Teleostei: Cyprinidae). Copeia1994:622-630Journal of the Arkansas Academy of Science, Vol 58, 2004110Journal of the Arkansas Academy of Science, Vol. 58 [2004], Art. 19http://scholarworks.uark.edu/jaas/vol58/iss1/19

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Unusual Hybognathus (Osteichthyes, Cyprinidae) from Lower White River, Arkansas

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