The Project Gutenberg eBook of Five Natural Hybrid Combinations in Minnows (Cyprinidae)

This ebook is for the use of anyone anywhere in the United States and most other parts of the world at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this ebook or online at www.gutenberg.org. If you are not located in the United States, you will have to check the laws of the country where you are located before using this eBook.

Title: Five Natural Hybrid Combinations in Minnows (Cyprinidae)

Author: Frank B. Cross

W. L. Minckley

Release date: April 12, 2011 [eBook #35838]

Language: English

Credits: Produced by Chris Curnow, Erica Pfister-Altschul, Joseph
Cooper and the Online Distributed Proofreading Team at
http://www.pgdp.net

*** START OF THE PROJECT GUTENBERG EBOOK FIVE NATURAL HYBRID COMBINATIONS IN MINNOWS (CYPRINIDAE) ***

Transcriber's Note

The follow suspected error has been corrected in this text: On page 3, C. erythogaster changed to C. erythrogaster.

University of Kansas Publications
Museum of Natural History

Volume 13, No. 1, pp. 1-18
June 1, 1960

Five Natural Hybrid Combinations
in Minnows (Cyprinidae)

BY
FRANK B. CROSS AND W. L. MINCKLEY

University of Kansas
Lawrence
1960

University of Kansas Publications, Museum of Natural History

Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
Robert W. Wilson

Volume 13, No. 1, pp. 1-18
Published June 1, 1960

University of Kansas
Lawrence, Kansas

PRINTED IN
THE STATE PRINTING PLANT
TOPEKA, KANSAS
1960

28-3424

Five Natural Hybrid Combinations
in Minnows (Cyprinidae)

BY
FRANK B. CROSS AND W. L. MINCKLEY

The hybrid fishes described herein are Chrosomus erythrogaster (Rafinesque) × Notropis cornutus frontalis (Agassiz), C. erythrogaster × Semotilus atromaculatus (Mitchill), Campostoma anomalum plumbeum (Girard) × S. atromaculatus, Gila nigrescens (Girard) × Rhinichthys cataractae (Valenciennes), and Notropis venustus venustus (Girard) × Notropis whipplei (Girard). Two of the combinations have been reported, without descriptions, in literature (citations below), and Hubbs (1955: Fig. 3) graphically indicated hybridization between the same genera with which this paper is concerned, but did not designate the species involved.

All specimens of C. erythrogaster × N. c. frontalis, C. erythrogaster × S. atromaculatus, C. a. plumbeum × S. atromaculatus, and N. v. venustus × N. whipplei were taken in a period of severe drought in Kansas and Arkansas. All were from small, spring-fed streams that support large populations of fishes. That the drought of 1953-1956 had pronounced effects on stream habitats in Kansas has been documented by Minckley and Cross (1959). Satisfactory sites for spawning may have been few, but an abundance of adult fishes persisted from earlier, wet years. Unusual crowding of spawning fishes would increase the opportunity for fertilization of the eggs of one species by sperm from another species. We think that the hybrids reported here (excepting G. nigrescens × R. cataractae) are explainable on the basis of crowding; we have no information about stream-conditions where the last-named hybrid was found. Generally, hybridization of fishes seems most common in areas that have been subject to radical climatic change in the past 20,000 or fewer years (Hubbs, 1955:18-19), and in streams that have been altered recently by the activities of man (Hubbs and Strawn, 1956:342, and others). Streams from which we report hybrids probably were affected by overgrazing of their watersheds; overgrazing was unusually severe in the drought.

Most of the hybrids were recognized as unusual at the time of capture, and were saved as part of numerically selective samples from the streams (rather than being discovered in the laboratory, in random samples).

Our measurements were made by methods defined by Hubbs and Lagler (1958); values are expressed as thousandths of the larger dimension.

Chrosomus erythrogaster × Notropis cornutus frontalis: KU 3872 (26.7 mm. in standard length) and KU 4170 (46.6 mm.) from Deep Creek, Riley Co., Kansas, Sec. 23, T. 11S, R. 7E, Dec. 14, 1957, and Apr. 26, 1958, respectively; and KU 4185 (39.3 mm.) from Bluff Creek, Pottawatomie Co., Kansas, Sec. 15, T. 6S, R. 8E, June 29, 1958. Compared in Table 1 with five specimens of C. erythrogaster, KU 3914 (39.3 to 47.3 mm., mean 43.0 mm.) from the same locality and of the same date as KU 3872 (above); and with five specimens of N. c. frontalis, KU 4184 (41.0 to 46.5 mm., mean 42.5 mm.) from the same locality and of the same date as KU 4185 (above). This cross has previously been recorded by Trautman (1957:326, 355) and by Minckley (1959:431).

The head-lengths of the hybrids are greater than in specimens of like size of C. erythrogaster or N. c. frontalis (Table 1). Hubbs and Miller (1943:373-374) reported that hybrids of Gila orcutti × Siphateles mohavensis have larger, more robust heads than either of the parental species, perhaps because of heterosis. The enlarged heads in hybrids of C. erythrogaster and N. c. frontalis result primarily from elongation of the postorbital region, with lesser elongation of the snout and orbit. The enlarged head affects measurements obtained for other structures that are parts of the head (and expressed as proportions of standard length or head-length), causing a tendency toward N. c. frontalis when the head-part is divided by standard length, and greater intermediacy or a tendency toward C. erythrogaster when the head-part is divided by head-length. In characters in which the parental species differ most (size of eye, length of upper jaw, and width of gape), the hybrids are intermediate between the parental species, regardless of whether the measurements are expressed as proportions of head-length or standard length; however, tendencies toward one or the other of the parental species (dependent on the divisor) can also been seen in these characters. Some experimentally propagated hybrids show highly variable, and sometimes extreme characters, rather than intermediacy of meristic and proportional characters (Hubbs, 1956).

Table 1. Comparisons of Three Specimens of Chrosomus erythrogaster × Notropis cornutus frontalis with Specimens of the Parental Species (means are above, ranges in parentheses below)

Chrosomus erythrogaster
KU 4170 and 4185
KU 3872
Notropis c. frontalis

Standard lengths
43.0
(39.3-47.3)
43.0
(39.3-46.6)
26.7
...
42.5
(41.0-46.5)

Head-length

Standard length

253
(246-262)
282
(280-283)
307
...
276
(273-283)

Orbital length

Standard length

067
(063-071)
075
(071-079)
101
...
083
(080-086)

Orbital length

Head-length

263
(252-272)
266
(250-282)
329
...
300
(291-310)

Snout-length

Standard length

069
(068-071)
073
(071-075)
071
...
068
(066-071)

Snout-length

Head-length

272
(262-280)
260
(255-265)
232
...
245
(233-260)

Interorbital width

Standard length

069
(065-071)
074
(069-079)
079
...
068
(067-069)

Interorbital width

Head-length

272
(262-286)
263
(245-280)
256
...
245
(241-250)

Gape-width

Standard length

056
(051-059)
065
(059-071)
064
...
065
(062-066)

Gape-width

Head-length

222
(204-241)
230
(209-250)
207
...
233
(224-239)

Upper jaw-length

Standard length

057
(051-061)
082
(076-088)
112
...
083
(080-086)

Upper jaw-length

Head-length

223
(206-237)
292
(273-311)
268
...
301
(284-315)

Postorbital length

Standard length

113
(108-120)
130
(129-130)
124
...
123
(121-125)

Postorbital length

Head-length

444
(432-456)
460
(455-464)
402
...
446
(431-457)

Length of depressed dorsal fin

Standard length

224
(217-232)
250
(247-252)
255
...
237
(233-243)

Length of depressed dorsal fin

Head-length

885
(869-892)
886
(871-900)
829
...
858
(836-890)

Number scales in lateral line
71.7
(68-76)
53.0
(53.0)
52(?)
...
38.8
(38-39)

Pharyngeal teeth
0,5-5,0
1,5-4,1
((?)-4,1)
1,5-4,2
2,4-4,2

Anal rays
8
8
8
usually 9

Vertebrae
37-40
39
...
38-39

In pigmentation, all three of the hybrids are intermediate between the parental species. The mid-lateral band (which is dark and discrete in C. erythrogaster, but faint, broad, and diffuse in N. c. frontalis) is broader and fainter in the hybrids than in Chrosomus, but is better developed than in N. c. frontalis. The dorsolateral dark band of C. erythrogaster is present in the hybrids, but is less distinct than in that species, and less distinct than the mid-lateral band of the hybrids themselves. The dorsolateral band is not present in N. c. frontalis. The color of the peritoneum in the hybrids is the glossy, jet-black of C. erythrogaster in two specimens, and the dusky-black of N. c. frontalis in one.

Chrosomus and Notropis differ greatly in the length and convolution of the intestine. Chrosomus has a long, coiled gut, which is crossed by the mid-ventral line eight or nine times; in N. c. frontalis, the intestine forms a flat, S-shaped loop that does not cross the mid-ventral line. In the two largest hybrids (KU 4170 and 4185), the gut is intermediate, crossing the mid-ventral line four times. In the smaller hybrid (KU 3872) the gut crosses the mid-ventral line twice but the configuration of the anterior loops indicates that the same intestinal convolutions that were found in the larger specimens would have developed in KU 3872 as the gut elongated with increase in size of the fish.

Both Deep and Bluff creeks are clear, gravel-bottomed streams draining parts of the Flint Hills Area of Kansas. A description of Flint Hills streams and lists of fishes occurring in them have been published by Minckley (1956 and 1959), and by Minckley and Cross (1959).

Chrosomus erythrogaster × Semotilus atromaculatus: KU 2947 (28.0 mm. in standard length) from Mill Creek, Wabaunsee Co., Kansas, Sec. 30, T. 12S, R. 9E, Mar. 22, 1953. Compared in Table 2 with five specimens of C. erythrogaster, KU 2836 (27.2 to 31.0 mm., mean 28.5) from the same locality and of the same date as KU 2947 (above); and with five specimens of S. atromaculatus, KU 1954, 2499, 2703, and 2838 (25.5 to 31.1 mm., mean 28.9 mm.) from streams in the same area.

This hybrid is intermediate between the two species in number of scales and pharyngeal teeth, and has a composite of the pigmentation found in the parental fishes (Table 2). For diagnostic purposes, greater importance is attached to the characters mentioned above than to proportional measurements, which are subject to considerable error because of the small size of the specimens. The few measurements that were taken indicate that this hybrid, like C. erythrogaster × N. c. frontalis, has a larger head than do specimens of like size of either parental species. The enlarged head affects measurements obtained for other structures that are parts of the head; only the length of the upper jaw, which is greatly different in the parental species, is actually intermediate in KU 2947.

Mill Creek is a clear stream, similar to Deep and Bluff creeks but somewhat larger. Mill Creek had an exceptionally large population of fishes at the time the hybrid was found, but Chrosomus and Semotilus were neither unusually common nor rare.

Two other crosses, both of which have been described in the literature, also have been found in Mill Creek. These are N. c. frontalis × S. atromaculatus, and N. c. frontalis × Notropis rubellus (Agassiz).

Table 2. Comparison of One Specimen of Chrosomus erythrogaster × Semotilus atromaculatus with Specimens of the Parental Species (means are above, ranges in parentheses below)

Chrosomus erythrogaster
KU 2947
Semotilus atromaculatus

Dark lateral band
intense
intense
intense

Light dorsolateral band
well-defined
poorly developed
absent

Dark dorsolateral band
intense
poorly developed
absent

Color of peritoneum
black
black
silvery

Length of gut
long with transverse coils
short, with a single forward loop
short, with a single forward loop

Pharyngeal teeth
0,5-5,0
1,5-5,2
usually 2,5-4,2

Number scales in lateral line
usually 70 or more, embedded
about 67 slightly embedded
usually fewer than 65, not embedded

Barbels
absent
absent
usually present

Vertebrae
37-40
39
42-43

Head-length

Standard length

272
(266-277)
310
300
(292-308)

Upper jaw-length

Standard length

071
(069-074)
097
110
(104-114)

Upper jaw-length

Head-length

263
(254-273)
310
366
(356-382)

Interorbital width

Standard length

103
(101-106)
114
116
(114-118)

Interorbital width

Head-length

381
(372-400)
372
388
(380-400)

Orbital length

Standard length

081
(075-085)
083
078
(076-084)

Orbital length

Head-length

296
(271-313)
267
261
(255-273)

Campostoma anomalum plumbeum × Semotilus atromaculatus: KU 4013 (three males, 86.0 to 96.0 mm. in standard length, mean 89.5 mm.) from Timber Creek, Scott Co., Kansas, Sec. 2, T. 16S, R. 33W, June 19, 1958. Compared in Table 3 with five specimens of C. a. plumbeum, KU 4034 (85.7 to 93.1 mm., mean 90.2 mm.) from the Smoky Hill River, Wallace Co., Kansas, Sec. 26, T. 13S, R. 39W, June 20, 1958; and with five specimens of S. atromaculatus, KU 4012 and 4047 (85.0 to 97.5 mm., mean 91.7 mm.) from the same locality and of the same date as KU 4013 (above), and Sappa Creek, Decatur Co., Kansas, Sec. 29, T. 2S, R. 28W, June 23, 1958, respectively. This hybrid combination has previously been recorded by Johnson (1945).

Table 3. Comparisons of Three Specimens of Campostoma anomalum plumbeum × Semotilus atromaculatus with Specimens of the Parental Species (means are above, ranges in parentheses below)

Campostoma a. plumbeum
KU 4013 (three spec.)
Semotilus atromaculatus

Standard lengths
90.2
(85.7-93.1)
89.5
(85.7-96.2)
91.7
(85.0-97.5)

Predorsal length

Standard length

511
(505-517)
533
(523-542)
557
(547-564)

Head-length

Standard length

251
(244-258)
276
(273-278)
289
(280-299)

Snout-length

Standard length

090
(086-096)
088
(087-091)
085
(082-087)

Orbital length

Standard length

044
(043-045)
048
(047-049)
049
(048-050)

Interorbital width

Standard length

075
(073-078)
094
(091-099)
110
(104-113)

Distance from tip of mandible to tip of maxillary

Standard length

057
(053-063)
076
(072-078)
098
(095-104)

Gill rakers (1st arch)
30
(29-31)
17
(16-18)
9
(8-10)

Number scales in lateral line
54
(53-55)
54
(54-55)
56
(52-64)

Predorsal scale-rows
25
(23-27)
27
(27-28)
35
(34-36)

Anal rays
7
(6-7)
7.3
(7-8)
8
8

Vertebrae
40
42-44[A]
42-43

[A] Three deformed vertebrae in one specimen with 44; other two specimens have 42 vertebrae.

The hybrids seem uniformly intermediate between the parental species. Application of the hybrid index to the characters listed in Table 3 results in a value of 55.7 when C. a. plumbeum is assigned the value 0.

The pharyngeal arches of the hybrids are peculiarly deformed. Expressed in terms of the one-or two-rowed arrangement common to all North American cyprinids, tooth-counts of 0,5-4,1; 1,3(?)-4,0; and 2,5-4,1 best fit the three fish. However, one arch bears only three teeth, all deformed and badly aligned, plus a pit that presumably represents a lost fourth tooth. At the other extreme, one arch bears eight teeth, some of which are attached to the arch between and behind others that are countable as part of the basic main row. Supernumerary teeth and other deformities may have resulted from abnormalities in the replacement process. In some cases, replacement teeth probably failed to develop; in others, replacement teeth seemingly developed, but attached to the arch in abnormal positions, with or without loss of previous teeth, causing irregularity in alignment. Hubbs (1951) described an irregular (seemingly three-rowed) alignment in a fish that Hay (1888:249) reported from western Kansas as Squalius elongatus. However, Hubbs considered the specimen to be an aberrant example of S. atromaculatus, and the characteristics that he lists for it do not correspond closely with those of the hybrid specimens that we have. Evans and Deubler (1955:32) found three rows of teeth in two of 150 specimens of Semotilus, and attributed the abnormality to failure of old teeth to fall out after formation of new teeth. The teeth of Campostoma usually number 0,4-4,0, and those of Semotilus 2,5-4,2. The pharyngeal arches are much smaller in Campostoma than in Semotilus.

The peritoneum is mottled dark and silvery in the hybrids; it has a composite of the coloration in the parental species rather than a blended shade. The intestine has two diagonal loops crossing the ventral part of the body cavity, and the hindgut lies high in the cavity, along the left side of the air bladder. In Campostoma, the long gut is transversely coiled around the air bladder, whereas in Semotilus the gut forms a longitudinal, flattened, S-shaped loop, ventral to the air bladder.

In the hybrids, the mouth is slightly oblique and nearly terminal. The lower lip is thick and fleshy, but has only a suggestion of the projecting mandibular shelf that is unique in Campostoma. The upper lip is uniform in width, not medially expanded as in S. atromaculatus. One of the hybrids lacks barbels, one has a Semotilus-like barbel on the right side only, and one has a vestigial barbel on the right side and an anomalous barbel that is nearly terminal on the left upper lip.

In coloration, the hybrids lack the spot in the anterior base of the dorsal fin that is characteristic of Semotilus, but each has a poorly-developed dark lateral band, and a weak basicaudal spot. This band and spot are usually prominently developed in S. atromaculatus and usually are absent in adults of C. a. plumbeum.

In the position and obliquity of the mouth, basic color pattern (diffuse lateral band and basicaudal spot), and the presence in one specimen of a nearly terminal, barbel-like structure, the hybrids somewhat resemble Hybopsis biguttata (Kirtland), which occurs rarely in the Kansas River Basin. These partial similarities are coincidental, because other characters of the hybrids make relationship with H. biguttata implausible. The high number of gill rakers (Table 3) and the length and position of the gut indicate strongly that the three specimens are hybrids with C. anomalum as one parent; the pharyngeal arches, though deformed, indicate that the other parental species has two rows of teeth, with five teeth in the main row. Only S. atromaculatus, among species in the Kansas River Basin, usually has such a dental formula, and other characters of our three specimens fit expectations in a hybrid between that species and C. a. plumbeum.

Timber Creek, where the three hybrids were collected, is a small, spring-fed, sandy-bottomed tributary to Scott County State Lake in the extreme southwestern part of the Kansas River Basin. The stream was less than 10 feet wide and six inches deep, except in three pools near road crossings. The hybrids were found in two of these pools, along with numerous S. atromaculatus and one adult C. a. plumbeum.

Another specimen of C. a. plumbeum × S. atromaculatus (KU 4841, 39.3 mm. in standard length) was taken in the North Platte River at Lisco, Garden County, Nebraska, on September 11, 1959. That specimen has 7 anal rays and 52 scales in the lateral line; otherwise, it is similar to the three hybrids described above.

Gila nigrescens × Rhinichthys cataractae: KU 4253 (a male, 60.6 mm. in standard length), from New Mexico, Bernalillo County, Rio Grande 12 mi. S Bernalillo on U. S. Highway 85 (Corraleo Bridge). Compared in Table 4 with six specimens of G. nigrescens: KU 4251, 4254, and 4262 (63.1-72.4 mm. in standard length, mean 66.4 mm.); and with five specimens of R. cataractae: KU 4248, 4258, and 4264 (55.6-65.0 mm. standard length, mean 59.5 mm.). Comparative material was taken at the same locality as KU 4253 and at nearby localities in the Rio Grande.

The hybrid is intermediate in almost all of the features in which the parental species differ from each other. For six of the characters included in Table 4, the hybrid index is 49.7 per cent, when Gila is assigned the value 0 (height of dorsal fin and numbers of fin rays and teeth excluded). There is no enlargement of the head in KU 4253, such as was found in Gila orcutti × Siphateles mohavensis (Hubbs and Miller, 1943:373), Chrosomus erythrogaster × Notropis cornutus frontalis, and C. erythrogaster × Semotilus atromaculatus. The height of the dorsal fin, which Hubbs and Miller (loc. cit.) found to be extreme in G. orcutti × S. mohavensis, exceeds the average for the parental species in G. nigrescens × R. cataractae also; but, dorsal fins as high as that of the hybrid were found in some individuals of both parental species. In R. cataractae, all fins are more rounded and more expansive than in G. nigrescens, and fins other than the dorsal have an intermediate size in the hybrid. This intermediacy has doubtful significance, because fin-size in Rhinichthys varies greatly with body-size, sex, and probably with the state of sexual development. Rhinichthys matures at smaller size than Gila, and never becomes so large as that species.

Gila nigrescens and R. cataractae differ strikingly in features involving the snout and mouth, and these differences provide the most conclusive evidence that KU 4253 is a hybrid of these species. The projecting, fleshy snout of R. cataractae is bridged to the ventral mouth by a frenum that is approximately 3 mm. wide in specimens 60 mm. in standard length. In Gila, the snout does not project beyond the mouth, which is oblique, lacks a frenum, and is larger than in Rhinichthys. The snout of the hybrid projects less than in R. cataractae and is bridged to the upper lip by a frenum 1.7 mm. wide. The mouth of the hybrid is intermediate in size, obliquity, and thickness of the lips. Rhinichthys has barbels, Gila lacks them, and the hybrid has one vestigial barbel, on the right side. The lower surface of the head of Rhinichthys is broad and flattened, with pronounced rugosity on the gular area and isthmus. In Gila the underside of the head is convex, with comparatively smooth membranes; the hybrid is intermediate, but tends toward Gila.

Table 4. Comparisons of One Specimen of Gila nigrescens × Rhinichthys cataractae with Specimens of the Parental Species (means are above, ranges in parentheses below)

Gila nigrescens
KU 4253
Rhinichthys cataractae

Standard lengths
66.4
(63.1-72.4)
60.6
59.5
(55.6-65.0)

Head-length

Standard length

282
(277-290)
281
281
(273-293)

Orbital length

Standard length

063
(063-065)
054
044
(041-047)

Snout-length

Standard length

083
(081-085)
092
106
(099-113)

Dorsal fin-height

Standard length

225
(212-238)
234
221
(206-234)

Postorbital length

Standard length

140
(134-142)
135
131
(127-136)

Distance from tip of mandible to tip of maxillary

Standard length

081
(079-085)
076
066
(064-069)

Length of infralabial groove

Standard length

060
(058-064)
045
036
(034-038)

Upper jaw
protractile
non-protractile
non-protractile

Number scales in lateral line
60
(58-63)
63
65
(63-67)

Anal fin-rays
8
(7-8)
7
7
(7)

Pelvic fin-rays
9
(9)
8
8
(8-9)

Pectoral fin-rays
16
(16-18)
16-15
13
(13-14)

Pharyngeal teeth
2,5-4,2
2,5-4,2
2,4-4,2

Table 5. Comparisons of One Specimen of Notropis v. venustus × Notropis whipplei with Specimens of the Parental Species, and with N. lutrensis × N. v. venustus. Measurements (lengths and depths) Are Expressed as Thousandths of Standard Length (means above, ranges in parentheses below)

Notropis whipplei
KU 3516
Notropis venustus, KU 3510
Notropis venustus, from Gibbs (1957a)
Notropis lutrensis × N. venustus

Standard length
50.6
(45.0-54.0)
47.8
47.3
(44.5-49.6)

44.7
(43.3-47.3)

Predorsal length
525
(513-535)
523
534
(519-547)
523
532
(528-538)

Dorsal origin to caudal base
497
(493-502)
508
497
(478-504)
496
508
(502-514)

Prepelvic length
505
(498-518)
492
505
(500-510)

499
(486-517)

Head-length
257
(250-262)
255
261
(256-267)
260
263
(261-267)

Caudal peduncle-length
217
(211-220)
221
224
(213-230)

224
(214-231)

Caudal peduncle-depth
110
(106-116)
119
127
(124-133)
125
126
(122-131)

Head-depth
170
(167-173)
182
186
(182-190)

190
(189-192)

Snout-length
079
(076-083)
079
080
(072-083)

081
(078-082)

Eye-diameter
069
(063-078)
069
070
(066-072)
073 [A]
070
(068-074)

Postorbital length, head
112
(108-115)
115
116
(112-120)

117
(115-120)

Upper jaw, length
078
(076-081)
077
081
(076-082)
079
077
(076-081)

Body depth
239
(233-248)
253
278
(261-288)
274
282
(275-294)

Lateral-line scales
36-37
36
36-38
36.5
(34-39)

Scales above lateral-line
13
14
15
15
(13-16)

Anal fin-rays
9
9
8
8
(7-8)

Pectoral fin-rays
14
(14-15)
14-14
15
(14-16)
14.2
(12-17)

Caudal spot
Absent
Present
Present
Present
Present

Vertebrae
37-38
38
37

[A] Orbital diameter.

The air bladder of KU 4253 is nearly as large as in Gila, and much larger than the degenerate air bladder of R. cataractae. Although the hybrid appears to be male, the gonads (especially the right one) are poorly developed. The hybrid is intermediate in curvature of the lateral line, which is nearly straight in Rhinichthys and strongly decurved in Gila.

Specimen No. 4253 is mostly pallid, resembling Gila much more than Rhinichthys in pigmentation. A mid-dorsal dark streak is conspicuous in the hybrid, especially anteriorly, but is less intense than in Gila. Rhinichthys lacks a well-developed dorsal stripe. The preorbital and suborbital areas are more heavily pigmented in the hybrid than in Gila, but not nearly so dark as in Rhinichthys. The hybrid has a faint dark basicaudal spot that is variably developed in Rhinichthys but absent in Gila.

Notropis venustus venustus × Notropis whipplei: KU 3516 (a male, 47.8 mm. in standard length), from Arkansas, Sevier Co., Winters Creek where it is crossed by U. S. Highway 71, 5 mi. N of Little River Bridge, March 8, 1956. Compared in Table 5 with four specimens of N. whipplei, KU 3517 (45.0-52.6 mm. in standard length, mean 50.6 mm.), same locality and date as KU 3516; four specimens of N. v. venustus, KU 3510 (44.5-49.6 mm. in standard length, mean 47.3 mm.), Louisiana, Winn Parish, Little Naches Bayou on U. S. Highway 71, 8.8 mi. NW Montgomery, March 4, 1956; three specimens of Notropis lutrensis (Baird and Girard) × N. v. venustus, KU 3510 (43.3-47.3 mm. in standard length, mean 44.7 mm.), same locality and date as N. v. venustus above; and with tabulated data on N. v. venustus from Gibbs (1957a:185-186). All specimens are from the lower Red River Drainage; other series of N. whipplei, N. venustus, and N. lutrensis × N. venustus, from the Red River Drainage and elsewhere, were examined but are not tabulated because of differences in size, and because of geographic variability that has been discussed by Gibbs (1957a).

The Subgenus Cyprinella of Notropis, to which N. venustus and N. whipplei belong, has been studied intensively by Gibbs (1957a and b). Notropis venustus differs conspicuously from N. whipplei in having a large dark basicaudal spot; also, N. venustus usually has 8 (rather than 9) anal rays, and 15 (rather than 13) scales above the lateral line immediately anterior to the dorsal fin. Specimens of N. v. venustus from the Red River Drainage, where the most robust representatives of the species are found, differ from N. whipplei in depth of head, body, and caudal peduncle (Table 5).

KU 3516 has a composite of the 9-rayed anal fin of N. whipplei and the caudal spot (albeit diffuse) of N. venustus; and, the hybrid is intermediate in body-proportions that distinguish the two species, especially depth of head, body, and caudal peduncle. In other features KU 3516 has values within the overlapping ranges of variation of whipplei and venustus except that the ratio of postdorsal length to standard length is extremely long in the hybrid, and the ratio of prepelvic length to standard length is extremely short (Table 5). Both extreme values for the hybrid seem to result from the cumulative influence of characters in which the parental species differ slightly in mean value (especially head-length, in which the hybrid is like whipplei, and caudal peduncle-length, in which the hybrid approaches venustus, despite the 9-rayed anal fin of the hybrid). The basicaudal spot of the hybrid is like that of N. v. venustus except for being less intense.

Notropis venustus hybridizes extensively with N. lutrensis (Hubbs, Kuehne, and Ball, 1953:226-230; Hubbs and Strawn, 1956), and that combination occurs in streams near the locality where KU 3516 was taken. KU 3516 resembles N. lutrensis × N. v. venustus in many ways, but is more slender than the latter hybrid. The depth of head, body, and caudal peduncle are greater in N. lutrensis than in N. venustus (much greater than in N. whipplei); therefore, specimens of N. lutrensis × N. venustus are usually deeper than N. venustus, whereas KU 3516 is less deep. KU 3516 has a rather sharp snout and thin, straight lips that are strongly suggestive of N. whipplei, rather than N. lutrensis, in which the snout is rounded and the lips are more obliquely decurved. There is less pigment underlying the anterior lateral-line scales in KU 3516 than in N. lutrensis × N. venustus, and melanophores on the scale-pockets of KU 3516 are arranged in narrower, more distinct submarginal bars than in N. lutrensis × N. venustus. Because of the difference in pigmentation, the lateral scales of N. whipplei (and of KU 3516) appear more narrowly diamond-shaped than the lateral scales of N. lutrensis or N. lutrensis × N. venustus. The lengths and heights of the scales are approximately the same in all three species.

Winters Creek, where KU 3516 was taken, flowed approximately five cubic feet per second at the time our collection was made; a landowner on the stream stated that it had been dry, except for pools, in the previous two summers. The water was somewhat gray, but nearly clear. The habitat consisted mainly of short riffles, with average depth of four inches, and pools to depths of two feet. Twelve species of fish, including N. whipplei but not N. lutrensis or N. venustus, were found; other minnows were Semotilus atromaculatus, N. chalybaeus, N. cornutus, N. umbratilis, and Campostoma anomalum.

LITERATURE CITED

Evans, H. E., and Deubler, Jr., E. E.

1955. Pharyngeal tooth replacement in Semotilus atromaculatus and Clinostomus elongatus, two species of cyprinid fishes. Copeia, 1955 (1):31-41, February 18.

Gibbs, Jr., R. H.

1957a. Cyprinid fishes of the Subgenus Cyprinella of Notropis. III. Variation and subspecies of Notropis venustus (Girard). Tulane Studies in Zoology, 5(8):175-203, August 7.

1957b. Cyprinid fishes of the Subgenus Cyprinella of Notropis. I. Systematic status of the Subgenus Cyprinella, with a key to the species exclusive of the lutrensis-ornatus complex. Copeia, 1957(3):185-195, August 26.

Hay, O. P.

1888. A contribution to the knowledge of the fishes of Kansas. Proc. U. S. Nat. Mus., 10:242-253, March 1.

Hubbs, C. L.

1951. Identification of cyprinid fish reported from Kansas as Squalius elongatus. Trans. Kansas Acad. Sci., 54(2):190-192, June 15.

1955. Hybridization between fish species in nature. Systematic Zoology, 4(1):1-20, March.

Hubbs, C. L., and Lagler, K. F.

1958. Fishes of the Great Lakes Region. Cranbrook Inst. Sci., Bull. 26, revised ed., xiii + 213 pp.

Hubbs, C. L., and Miller, R. R.

1943. Mass hybridization between two genera of cyprinid fishes in the Mohave Desert, California. Papers Michigan Acad. Sci., Arts, and Lett., 28(1942):343-378, pls. 1-4, February.

Hubbs, C.

1956. Relative variability of hybrids between the minnows, Notropis lepidus and N. proserpinus. Texas Jour. Sci., 8 (4):463-469, December.

Hubbs, C., Kuehne, R. A., and Ball, J. C.

1953. The fishes of the upper Guadalupe River, Texas. Texas Jour. Sci., 5(2):216-244, June.

Hubbs, C., and Strawn, K.

1956. Interfertility between two sympatric fishes, Notropis lutrensis and Notropis venustus. Evolution, 10(4):341-344, December.

Johnson, R.

1945. Ever hook a hybrid? Minnesota Conservation Volunteer, 8(49): 18-22.

Minckley, W. L.

1956. A fish survey of the Pillsbury Crossing Area, Deep Creek, Riley County, Kansas. Trans. Kansas Acad. Sci., 59(3):351-357, October 31.

1959. Fishes of the Big Blue River Basin, Kansas. Univ. Kans. Publ., Mus. Nat. Hist., 11(7):401-442, May 8.

Minckley, W. L., and Cross, F. B.

1959. Distribution, habitat, and abundance of the Topeka shiner, Notropis topeka (Gilbert) in Kansas. Amer. Midl.-Nat., 61(1):210-217.

Trautman, M. B.

1957. The fishes of Ohio. Ohio State Univ. Press, xviii + 683 pp.

Transmitted March 2, 1960.

◻
28-3424

*** END OF THE PROJECT GUTENBERG EBOOK FIVE NATURAL HYBRID COMBINATIONS IN MINNOWS (CYPRINIDAE) ***

Updated editions will replace the previous one—the old editions will be renamed.

Creating the works from print editions not protected by U.S. copyright law means that no one owns a United States copyright in these works, so the Foundation (and you!) can copy and distribute it in the United States without permission and without paying copyright royalties. Special rules, set forth in the General Terms of Use part of this license, apply to copying and distributing Project Gutenberg™ electronic works to protect the PROJECT GUTENBERG™ concept and trademark. Project Gutenberg is a registered trademark, and may not be used if you charge for an eBook, except by following the terms of the trademark license, including paying royalties for use of the Project Gutenberg trademark. If you do not charge anything for copies of this eBook, complying with the trademark license is very easy. You may use this eBook for nearly any purpose such as creation of derivative works, reports, performances and research. Project Gutenberg eBooks may be modified and printed and given away—you may do practically ANYTHING in the United States with eBooks not protected by U.S. copyright law. Redistribution is subject to the trademark license, especially commercial redistribution.

START: FULL LICENSE

THE FULL PROJECT GUTENBERG LICENSE

PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK

To protect the Project Gutenberg™ mission of promoting the free distribution of electronic works, by using or distributing this work (or any other work associated in any way with the phrase “Project Gutenberg”), you agree to comply with all the terms of the Full Project Gutenberg™ License available with this file or online at www.gutenberg.org/license.

Section 1. General Terms of Use and Redistributing Project Gutenberg™ electronic works

1.A. By reading or using any part of this Project Gutenberg™ electronic work, you indicate that you have read, understand, agree to and accept all the terms of this license and intellectual property (trademark/copyright) agreement. If you do not agree to abide by all the terms of this agreement, you must cease using and return or destroy all copies of Project Gutenberg™ electronic works in your possession. If you paid a fee for obtaining a copy of or access to a Project Gutenberg™ electronic work and you do not agree to be bound by the terms of this agreement, you may obtain a refund from the person or entity to whom you paid the fee as set forth in paragraph 1.E.8.

1.B. “Project Gutenberg” is a registered trademark. It may only be used on or associated in any way with an electronic work by people who agree to be bound by the terms of this agreement. There are a few things that you can do with most Project Gutenberg™ electronic works even without complying with the full terms of this agreement. See paragraph 1.C below. There are a lot of things you can do with Project Gutenberg™ electronic works if you follow the terms of this agreement and help preserve free future access to Project Gutenberg™ electronic works. See paragraph 1.E below.

1.C. The Project Gutenberg Literary Archive Foundation (“the Foundation” or PGLAF), owns a compilation copyright in the collection of Project Gutenberg™ electronic works. Nearly all the individual works in the collection are in the public domain in the United States. If an individual work is unprotected by copyright law in the United States and you are located in the United States, we do not claim a right to prevent you from copying, distributing, performing, displaying or creating derivative works based on the work as long as all references to Project Gutenberg are removed. Of course, we hope that you will support the Project Gutenberg™ mission of promoting free access to electronic works by freely sharing Project Gutenberg™ works in compliance with the terms of this agreement for keeping the Project Gutenberg™ name associated with the work. You can easily comply with the terms of this agreement by keeping this work in the same format with its attached full Project Gutenberg™ License when you share it without charge with others.

1.D. The copyright laws of the place where you are located also govern what you can do with this work. Copyright laws in most countries are in a constant state of change. If you are outside the United States, check the laws of your country in addition to the terms of this agreement before downloading, copying, displaying, performing, distributing or creating derivative works based on this work or any other Project Gutenberg™ work. The Foundation makes no representations concerning the copyright status of any work in any country other than the United States.

1.E. Unless you have removed all references to Project Gutenberg:

1.E.1. The following sentence, with active links to, or other immediate access to, the full Project Gutenberg™ License must appear prominently whenever any copy of a Project Gutenberg™ work (any work on which the phrase “Project Gutenberg” appears, or with which the phrase “Project Gutenberg” is associated) is accessed, displayed, performed, viewed, copied or distributed:

This eBook is for the use of anyone anywhere in the United States and most other parts of the world at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org. If you are not located in the United States, you will have to check the laws of the country where you are located before using this eBook.

1.E.2. If an individual Project Gutenberg™ electronic work is derived from texts not protected by U.S. copyright law (does not contain a notice indicating that it is posted with permission of the copyright holder), the work can be copied and distributed to anyone in the United States without paying any fees or charges. If you are redistributing or providing access to a work with the phrase “Project Gutenberg” associated with or appearing on the work, you must comply either with the requirements of paragraphs 1.E.1 through 1.E.7 or obtain permission for the use of the work and the Project Gutenberg™ trademark as set forth in paragraphs 1.E.8 or 1.E.9.

1.E.3. If an individual Project Gutenberg™ electronic work is posted with the permission of the copyright holder, your use and distribution must comply with both paragraphs 1.E.1 through 1.E.7 and any additional terms imposed by the copyright holder. Additional terms will be linked to the Project Gutenberg™ License for all works posted with the permission of the copyright holder found at the beginning of this work.

1.E.4. Do not unlink or detach or remove the full Project Gutenberg™ License terms from this work, or any files containing a part of this work or any other work associated with Project Gutenberg™.

1.E.5. Do not copy, display, perform, distribute or redistribute this electronic work, or any part of this electronic work, without prominently displaying the sentence set forth in paragraph 1.E.1 with active links or immediate access to the full terms of the Project Gutenberg™ License.

1.E.6. You may convert to and distribute this work in any binary, compressed, marked up, nonproprietary or proprietary form, including any word processing or hypertext form. However, if you provide access to or distribute copies of a Project Gutenberg™ work in a format other than “Plain Vanilla ASCII” or other format used in the official version posted on the official Project Gutenberg™ website (www.gutenberg.org), you must, at no additional cost, fee or expense to the user, provide a copy, a means of exporting a copy, or a means of obtaining a copy upon request, of the work in its original “Plain Vanilla ASCII” or other form. Any alternate format must include the full Project Gutenberg™ License as specified in paragraph 1.E.1.

1.E.7. Do not charge a fee for access to, viewing, displaying, performing, copying or distributing any Project Gutenberg™ works unless you comply with paragraph 1.E.8 or 1.E.9.

1.E.8. You may charge a reasonable fee for copies of or providing access to or distributing Project Gutenberg™ electronic works provided that:

• You pay a royalty fee of 20% of the gross profits you derive from the use of Project Gutenberg™ works calculated using the method you already use to calculate your applicable taxes. The fee is owed to the owner of the Project Gutenberg™ trademark, but he has agreed to donate royalties under this paragraph to the Project Gutenberg Literary Archive Foundation. Royalty payments must be paid within 60 days following each date on which you prepare (or are legally required to prepare) your periodic tax returns. Royalty payments should be clearly marked as such and sent to the Project Gutenberg Literary Archive Foundation at the address specified in Section 4, “Information about donations to the Project Gutenberg Literary Archive Foundation.”

• You provide a full refund of any money paid by a user who notifies you in writing (or by e-mail) within 30 days of receipt that s/he does not agree to the terms of the full Project Gutenberg™ License. You must require such a user to return or destroy all copies of the works possessed in a physical medium and discontinue all use of and all access to other copies of Project Gutenberg™ works.

• You provide, in accordance with paragraph 1.F.3, a full refund of any money paid for a work or a replacement copy, if a defect in the electronic work is discovered and reported to you within 90 days of receipt of the work.

• You comply with all other terms of this agreement for free distribution of Project Gutenberg™ works.

1.E.9. If you wish to charge a fee or distribute a Project Gutenberg™ electronic work or group of works on different terms than are set forth in this agreement, you must obtain permission in writing from the Project Gutenberg Literary Archive Foundation, the manager of the Project Gutenberg™ trademark. Contact the Foundation as set forth in Section 3 below.

1.F.

1.F.1. Project Gutenberg volunteers and employees expend considerable effort to identify, do copyright research on, transcribe and proofread works not protected by U.S. copyright law in creating the Project Gutenberg™ collection. Despite these efforts, Project Gutenberg™ electronic works, and the medium on which they may be stored, may contain “Defects,” such as, but not limited to, incomplete, inaccurate or corrupt data, transcription errors, a copyright or other intellectual property infringement, a defective or damaged disk or other medium, a computer virus, or computer codes that damage or cannot be read by your equipment.

1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the “Right of Replacement or Refund” described in paragraph 1.F.3, the Project Gutenberg Literary Archive Foundation, the owner of the Project Gutenberg™ trademark, and any other party distributing a Project Gutenberg™ electronic work under this agreement, disclaim all liability to you for damages, costs and expenses, including legal fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH DAMAGE.

1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a defect in this electronic work within 90 days of receiving it, you can receive a refund of the money (if any) you paid for it by sending a written explanation to the person you received the work from. If you received the work on a physical medium, you must return the medium with your written explanation. The person or entity that provided you with the defective work may elect to provide a replacement copy in lieu of a refund. If you received the work electronically, the person or entity providing it to you may choose to give you a second opportunity to receive the work electronically in lieu of a refund. If the second copy is also defective, you may demand a refund in writing without further opportunities to fix the problem.

1.F.4. Except for the limited right of replacement or refund set forth in paragraph 1.F.3, this work is provided to you ‘AS-IS’, WITH NO OTHER WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PURPOSE.

1.F.5. Some states do not allow disclaimers of certain implied warranties or the exclusion or limitation of certain types of damages. If any disclaimer or limitation set forth in this agreement violates the law of the state applicable to this agreement, the agreement shall be interpreted to make the maximum disclaimer or limitation permitted by the applicable state law. The invalidity or unenforceability of any provision of this agreement shall not void the remaining provisions.

1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the trademark owner, any agent or employee of the Foundation, anyone providing copies of Project Gutenberg™ electronic works in accordance with this agreement, and any volunteers associated with the production, promotion and distribution of Project Gutenberg™ electronic works, harmless from all liability, costs and expenses, including legal fees, that arise directly or indirectly from any of the following which you do or cause to occur: (a) distribution of this or any Project Gutenberg™ work, (b) alteration, modification, or additions or deletions to any Project Gutenberg™ work, and (c) any Defect you cause.

Section 2. Information about the Mission of Project Gutenberg™

Project Gutenberg™ is synonymous with the free distribution of electronic works in formats readable by the widest variety of computers including obsolete, old, middle-aged and new computers. It exists because of the efforts of hundreds of volunteers and donations from people in all walks of life.

Volunteers and financial support to provide volunteers with the assistance they need are critical to reaching Project Gutenberg™’s goals and ensuring that the Project Gutenberg™ collection will remain freely available for generations to come. In 2001, the Project Gutenberg Literary Archive Foundation was created to provide a secure and permanent future for Project Gutenberg™ and future generations. To learn more about the Project Gutenberg Literary Archive Foundation and how your efforts and donations can help, see Sections 3 and 4 and the Foundation information page at www.gutenberg.org.

Section 3. Information about the Project Gutenberg Literary Archive Foundation

The Project Gutenberg Literary Archive Foundation is a non-profit 501(c)(3) educational corporation organized under the laws of the state of Mississippi and granted tax exempt status by the Internal Revenue Service. The Foundation’s EIN or federal tax identification number is 64-6221541. Contributions to the Project Gutenberg Literary Archive Foundation are tax deductible to the full extent permitted by U.S. federal laws and your state’s laws.

The Foundation’s business office is located at 809 North 1500 West, Salt Lake City, UT 84116, (801) 596-1887. Email contact links and up to date contact information can be found at the Foundation’s website and official page at www.gutenberg.org/contact

Section 4. Information about Donations to the Project Gutenberg Literary Archive Foundation

Project Gutenberg™ depends upon and cannot survive without widespread public support and donations to carry out its mission of increasing the number of public domain and licensed works that can be freely distributed in machine-readable form accessible by the widest array of equipment including outdated equipment. Many small donations ($1 to $5,000) are particularly important to maintaining tax exempt status with the IRS.

The Foundation is committed to complying with the laws regulating charities and charitable donations in all 50 states of the United States. Compliance requirements are not uniform and it takes a considerable effort, much paperwork and many fees to meet and keep up with these requirements. We do not solicit donations in locations where we have not received written confirmation of compliance. To SEND DONATIONS or determine the status of compliance for any particular state visit www.gutenberg.org/donate.

While we cannot and do not solicit contributions from states where we have not met the solicitation requirements, we know of no prohibition against accepting unsolicited donations from donors in such states who approach us with offers to donate.

International donations are gratefully accepted, but we cannot make any statements concerning tax treatment of donations received from outside the United States. U.S. laws alone swamp our small staff.

Please check the Project Gutenberg web pages for current donation methods and addresses. Donations are accepted in a number of other ways including checks, online payments and credit card donations. To donate, please visit: www.gutenberg.org/donate.

Section 5. General Information About Project Gutenberg™ electronic works

Professor Michael S. Hart was the originator of the Project Gutenberg™ concept of a library of electronic works that could be freely shared with anyone. For forty years, he produced and distributed Project Gutenberg™ eBooks with only a loose network of volunteer support.

Project Gutenberg™ eBooks are often created from several printed editions, all of which are confirmed as not protected by copyright in the U.S. unless a copyright notice is included. Thus, we do not necessarily keep eBooks in compliance with any particular paper edition.

Most people start at our website which has the main PG search facility: www.gutenberg.org.

This website includes information about Project Gutenberg™, including how to make donations to the Project Gutenberg Literary Archive Foundation, how to help produce our new eBooks, and how to subscribe to our email newsletter to hear about new eBooks.