Southwestern Association of Naturalists
A New Intergeneric Cyprinid Hybrid (Notropis pilsbryi X Chrosomus erythrogaster) from Oklahoma Author(s): Henry W. Robison and Rudolph J. Miller Source: The Southwestern Naturalist, Vol. 16, No. 3/4 (Feb. 18, 1972), pp. 442-444 Published by: Southwestern Association of Naturalists Stable URL: http://www.jstor.org/stable/3670081 . Accessed: 02/12/2014 17:33 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp
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A NEW INTERGENERIC CYPRINID HYBRID (NOTROPIS PILSBRYI x CHROSOMUS ERYTHROGASTER) FROM OKLAHOMA- We collecteda hybrid betweenthe duskystripedshiner,NotropispilsbryiFowler,and the southernredfromCloudCreekat StateHighway bellydace,Chrosomus erythrogaster Rafinesque, 116,Delaware County,Oklahomaon 11 October1969.The specimenis on depositat This appearsto be the firstdocumented OklahomaStateUniversity. occurrence of thishybridcombination. Phillipsand Etnier(J. Minn.Acad. Sci.,35: 96-97,1969) statedthatC. erythroanomagasteris knownto hybridizewithseveralcyprinids, includingCampostoma lum (Hubbs and Bailey, Pap. Mich. Acad. Sci., Arts and Lett.,37: 143, 1952), Clinostomuselongatus (Trautman,Fishes of Ohio, Ohio State Univ., 1957), Clinostomusfunduloides(Trautman, loc. cit.), Semotilus atromaculatusand Notropis
cornutus(Crossand Minckley,Publ. Univ.Kan. Mus. Hist.,13: 4, 1960; Minckley, Publ. Univ. Kan. Mus. Nat. Hist.,11: 431, 1959), but did notmentionthepresent N. pilsbryihas been recordedto hybridizewithDionda nubila and combination. Notropisrubellus(Moore and Paeden,Am. Midl. Nat.,44: 92, 1950). Five comparably sizedspecimens ofeach parenttypewereselectedforcomparison withthehybrid.Ten morphometric characters weremeasuredtothenearest0.1 mm andcountswereaveraged characters werecounted.Measurements and eightmeristic meansare presented withthehybrid fortheparentspeciessamplesand theresultant valuesin table1. TABLE 1 characteristics ofmeristic and morphometric ofhybridNotropispilsbryi Comparison X Chrosomuserythrogasterand both parental species N. pilsbryi
Pharyngealteeth Standardlength Laterallinescales Predorsalscales ScalesaboveL.1. ScalesbelowL.1. Circumference scales Anal rays Pectoralrays Dorsalrays Predorsallength* Postdorsal length Bodydepth Caudalped.depth Snoutlength Eye length Post-orbital length Widthofdorsalband Lengthofmid-caudal rays Averagehybridindex *
2,4-4,2 65.8 40.6 16.2 6.8 4.8 29.2 9.0 17.8 8.0 .496 .535 .204 .089 .072 .084 .114 .027 .123
Hybrid
C. erythrogaster
1,5-4,1 64.2 57 25 11 7 43 8 17 8 .505 .530 .206 .099 .073 .072 .122 .022 .147
0,5-5,0 56.2 80.0 43.0 16.4 13.8 71.4 8.0 15.2 8.0 .558 .498 .220 .135 .067 .063 .118 .017 .159
Expressed as thousandths of standard length.
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Index
42 33 44 24 33 100 32 15 14 13 22 57 50 67 39.00
Hybrid index values were calculated according to the method describedin Hubbs, et al. (Cont. Lab. Vert. Biol., 22: 6-8, 1943). Characteristicsof the N. pilsbryisample were assigned index values of 0 while those of the C. erythrogastersample were assigned values of 100. The calculated value for each characteristicof the hybrid gives an indication of a relative positionbetween (usually) the two parental values. The mean of all values calculated for hybrids usually approaches 50, although table 1 shows the present hybrid to resemble N. pilsbryi somewhat more closely in the total aggregate of measured characteristics(perhaps because the specimens were of more equal size). The hybrid is closer to N. pilsbryiin 10 of the 14 characteristicstabulated. Pharyngeal teeth countsrevealed the hybridto be preciselyintermediate between the parental forms. The overall appearance of the hybrid is somewhat more similar to N. pilsbryi than to C. erythrogaster(Fig. 1), but tends to be intermediatein most pigmentary and configurationalcharacteristics.Snout length and post-orbitallength, however, are slightlylarger in the hybridthan in either parent species. Likewise, both parent species have a distinct,broad lateral band and a narrow dorsolateral band, whereas
Fig.1. Lateral view of Notropispilsbryi,NotropispilsbryiX Chrosomuserythrogoaster and Chrosomus fromtopto bottom. erythrogaster,
443
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the dorsolateral band is poorly developed in the hybrid. A prominentcaudal spot slightly differentiatedfromthe lateral band seems to be present iri the hybrid and in C. erythrogaster.A decrease in scale size coupled with retentionof the orderly position of scale rows foundin N. pilsbryihas createdthe apparent presence of about 5 faint horizontal lines above each dorsolateral band of the hybrid; such bands are not evidentin eitherparent species. The lateral line is incompletein C. erythrogaster, but complete in the hybrid and in N. pilsbryi. In summary, this hybrid is fairly typical of most cyprinidhybridsin that most characteristicsappear to be more similar to one or the other parent species while a few are close to precise intermediacy and the overall morphologyof the hybridapproaches intermediacy. It seems likely that this individual, like most cyprinidhybrids,was the result of random cross-fertilizationrather than any breakdown in behavioral isolating mechanisms. Both species spawn close to the gravel bottomor over pebble nests of other cyprinids. Hankinson (Pap. Mich. Acad. Sci., Arts and Lett., 15: 411-425, 1932) and Raney (Zoologica, 32: 125-132, 1947) observed breeding swarms of C. erythrogasterand C. oreas, respectively,spawning over Nocomis nests in Michigan and Virginia. Miller (Southwest. Nat., 12: 463-468, 1967) observed a breeding aggregate of N. pilsbryi over a Semotilus atromaculatus nest in eastern Oklahoma. Since both S. atromaculatus and Nocomis biguttatusare found in Cloud Creek, a reasonable guess about the hybrid'sorigin might be that both parental species were spawning over the same pebble nest,with some chance combinationof contraspecific gametes occurring.-Henry W. Robison and Rudolph I. Miller, Department of Zoology, Oklahoma State University,Stillwater, 74074. Present address of Robison: Department of Biology, Southern State College, Magnolia, Arkansas 71753. Since the manuscript was submitted the American genus Chrosomes has been placed in the synonomyof the European genus Phozinus, thereforethe correctname of the southernredbellydace is Phoxinus erythrogaster. STERNOTHAERUS MINOR PELTIFER IN LOUISIANA.-A specimen of Sternothaerus minor peltiferSmith and Glass was collected by Crain on 1 August 1966, 1.75 mi S and 0.75 mi W of State Line, Washington Parish, from Stubbs Creek, a small stream in the Pearl River drainage system,using a small fishhook baited with an earthworm.This is apparently the firstspecimen of this subspecies from within the boundaries of Louisiana, although a specimen was reported from the Pearl River (Louisiana-Mississippi boundary) by Tinkle (Tulane Stud. Zool., 6(1): 1-56, 1958). The specimen is LSUMZ 16996 in the Louisiana State University Museum of Zoology. Features of pattern of this turtle suggested that it might be an aberrant S. carinatus. Specimens of S. m. peltiferand S. carinatus from southern and eastern Mississippi (part of the collections of the Department of Biology, University of Southern Mississippi) were consequentlyexamined for comparisonwith the Louisiana specimen. The high carapace and mid-vertebralkeel typical of S. carinatus are not present in any of the Mississippi S. m. peltifernor in the Louisiana specimen. The carapace angle of the Washington Parish specimen approaches 1800. The carapace height is 44 mm; the length 123 mm. A slight dorsal keel on the posteriorvertebral is the only evidence of a mid-vertebralkeel. One gular scute, typical of S. m. peltifer,is present in the Washington Parish 444
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