Cynolebias alexandri Castello & Lopez 1974, sp. nov.
Creators: name: Castello, Hugo Patricio
name: Lopez, Rogelio Bartolome
Publisher: name: Zenodo
Year: 1974
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Cyprinodontiformes
Rivulidae
Cynolebias
Cynolebias alexandri

description: Cynolebias alexandri Castello & Lopez, sp. nov. *   
 Holotype male; Ichthyol.; M.A.C.N. #6438 (total length 44 mm; standard length 36 mm). Type locality: Parque Unzue, Gualeguaychu, Provincia de Entre Rios. Collector: Mr. R. Barbetti, 13/X/1972.   
 Allotype female: M.A.C.N. #6439 (total length 41 mm; standard length 32 mm). Same locality and data as holotype.   
 Paratypes: #1-4 (1 male, 3 females): M.A.C.N. #6437 (total lengths 41- 29 mm; standard lengths 32- 23 mm). Locality: Gualeguaychu, Provincia de Entre Rios. Coll.: Mr.J.O. Fernandez-Santo, and Mr. J. Castelli. 20 /VII/1972.   
#5-11 (4 males, 3 females): M.A.C.N. #6425 (total lengths 53-82 mm; standard lengths 43- 24 mm). Locality: As in the holotype.  
 • C. alexandri is so named by request of aquarists Fernandez-Santo and Castelli, from Buenos Aires, who discovered the species at Entre Rios, Argentina.   
#12-18 (5 males. 2 females): M.A.C.N. #2738 (total lengths 33- 27 mm; standard lengths 26- 21 mm). Locality: Gualeguaychu, Provincia de Entre Rios. Coll.: Miss M.L Elizalde. 17/IV/1941.  
 Diagnosis: Males with 7-10 dark vertical bars on the grayish green sides of the body, not counting the one passing through the eye; dorsal and anal fins begin on second of total length; a small dark spot on the first three dorsal rays, less conspicuous than one on the anal fin; ins reddish; body long and thin. Dorsal fin of female begins about middle of body; females without vertical bars.   
 Males: Dorsal rays 22-24 Females: Dorsal rays 17-18   
Anal rays 21-24 Anal rays 18-19  
 Description of Holotype male: Standard length 36 mm. Head 3.6 in standard length; eye 4.0 in head and 1.5 in interorbital space. Pectoral fin with 11 rays, short, almost equal to head length. Dorsal fin with 24 rays, originating on second third of body length about over tip of pectoral fin, its height 1.4 in head length and its base 2.3 in standard length. Anal fin with 24 rays, beginning precisely between third and fourth vertical bars; fin slightly higher than, and with its base almost equal to, that of the dorsal fin. Caudal fin with 21 rays, rounded. Twenty-six scales along a mid-longitudinal line.   
The vertical bars are placed as follows: a short one below the eye, rather wide, but narrower above; eight black bars on right side, the first at pectoral fin base, the second on the end of the same fin. the third ending ventrally at the anal origin, the fourth to the seventh extending from the dorsal to the anal fins, the eighth inconspicuous and encircling the caudal peduncle. The first to seventh bars are increasingly wider and curved toward the direction of the head; the seventh is almost straight. These bars are almost vertical on the left side.  
 Description of the Allotype: Standard length 32 mm. Head 3.2 in standard length; eye 3.5 in head and 1.3 in interorbital space. Pectoral fin with 10 rays, 1.2 in head length. Dorsal fin with 19 rays, originating in the middle of the body like the anal fin, its height 1.8 in head length and its base almost equal to the head. Anal fin with 21 rays, deeper than the dorsal fin, 1,5 in head length, and its base 1.2 in head length. Caudal fin with 22 rays, rounded.   
The color pattern consists of dark irregular spots, especially on the posterior half of the body.  
 Color of live males: The background color is a delicate gray-greenish with 7-10 darkish vertical bars, some of them curved, from the posterior margin of the opercle to the caudal peduncle; they are narrower than the light interspaces. A bar just behind the opercle is incomplete and inconspicuous. An oblique bar crosses the jaw and reaches the upper edge of the orbit. There is an opercular spot of iridescent grayish color. When males are resting or not excited, the bars are less evident except for the first three or those placed before the dorsal and anal fins.   
The fins are black in formalin-preserved specimens, blue in live animals. There are small darkish spots alternating with translucent spaces on the base of the dorsal fin and continuous with the vertical bars. From the spots, two lines of chromatophores bifurcate, each one superimposed with a dorsal fin ray. The first three dorsal and anal fin rays are darkly pigmented, the pectoral fins are translucent, and the pelvic fins black. The dorsal, anal, and caudal fins of an excited specimen exhibited small greenish ocelli against a dark blue background. The anal fin is fringed by an iridescent greenish band.  
 Color of live females: The females are brown with small irregular darkish spots all over the body, more evident on the posterior half of the body. They do not exhibit vertical bars like the males, nor the two caudal peduncle spots as in the case of C. adloffi from Brazil. A short bar passes through the eye. The vertical fins are spotted.   
 Comparisons: Cynolebias alexandri is most closely related to (C. adloffi, C. viarius, C. cheradophilus, and C. luteoflammulatus. but differs from these in details of color pattern and in fins. These species are contrasted in the accompanying table. C. alexandri s eems to be closest to C. luteoflammulatus, males having a grayish-green background color instead of orangish as in C. luteoflammulatus. In female C. luteoflammulatus the dorsal origin is at the second third of the body as in the male; C. alexandri is sexually dimorphic in this character, the female dorsal originating at mid body, the male at the second third.   
 We wish to express our gratitude for the invaluable assistance of our colleagues and to aquarists J.O. Fernandez-Santo and J. Castelli from Buenos Aires, Argentina; also to Dr. R. Vaz Ferreira from Montevideo and to Dr. Herbert R. Axelrod of T.F.H. Publications, who aided us in the recognition and description of this new species Cynolebias.
description: Published as part of Castello, Hugo Patricio & Lopez, Rogelio Bartolome, 1974, Cynolebias alexandri, a new species of annual killifish from Argentina, with notes on C. bellottii, pp. 34-40 in Tropical Fish Hobbyist 23 (1) on pages 35-40, DOI: 10.5281/zenodo.11130390