ZOOLOGISCHE ABHANDLUNGEN - hotelwebservice€¦ · ZOOLOGISCHE ABHANDLUNGEN Staatliches Museum fur Tierkunde Dresden Band 51 Ausgegeben: 10. Dezember2001 Description of Cnesterodon

ZOOLOGISCHE ABHANDLUNGEN Staatliches Museum fur Tierkunde Dresden

Band 51 Ausgegeben: 10. Dezember2001

Description of Cnesterodon raddai sp. n. from a swamp near Resistencia, Rio Parana basin,

Argentina (Teleostei: Cyprinodontiformes: Poeciliidae)

With 1 table and 4 figures

MANFRED K. MEYER & VOLLRAD ETZEL

Nr. 17

Ab stra et . Cnesterodonraddai sp. n . (locus typicus: swamp near Resistencia, Rio Rarana basin, Argentina), is described, illustrated and compared to all members of the genus Cnesterodon. The new species is closely related to Cnesterodon decemmaculatus (JENYNS). Cnesterodon raddai sp. n. differs from all hitherto known members of the genus Cnestero­don in morphological characters and colouration.

Resume n. Cnesterodon raddai sp. n. (localidad tipo: Resistencia, Rio Parana basin, Ar­gentina) es descrita, ilustraqa y comparada con todos los miembros del genero Cnestero­don. La nueva especie esta estrechamente relacionada con Cnesterodon decemmaculatus (JENYNS). Cnesterodon raddai sp . n. difiere de los otros miembros del genero Cnesterodon en carateristicas morfol6gicas y coloraci6n.

Kurz fas sung . Beschreibung von Cnesterodon raddai sp. n. aus einem Sumpf bei Re­sistencia, Becken des Rio Parana, Argentinien (Teleostei: Cyprinodontiformes: Poeci­liidae). - Cnesterondon raddai sp. n . (locus typicus: Sumpf bei Resistencia, Becken des Rio Parana, Argentinien) wird beschrieben, abgebildet sowie mit allen bisher bekannten Cnesterodon-Taxa verglichen. Die neue Art ist eng mit Cnesterodon decemmaculatus (JENYNS) verwandt und unterscheidet sich von allen anderen Cnesterodon-Arten in mor­phologischen Merkmalen und Farbmustern.

Key words . Cyprinodontiformes, Poeciliidae, Cnesterodon, taxonomy, new species, Ar­gentina.

Introduction

The poeciliid genus Cnesterodon GARMAN (1895) with the type species, decemmaculatus (JENYNS, 1842), by monotypy, from Maldonado, Uruguay, included until now six valid spe­cies. All taxa of the genus are distributed in southeastern South America, from the Mato Grosso, Brazil to Argentina.

ROSA & COSTA (1993) recognized for Cnesterodon, together with the type species, the fol­lowing taxa: carnegiei HASEMAN, 1911 from Serrinha, Rio Iguassu, Parana, Brazil, breviro­stratus ROSA & COSTA, 1993 from Rio das Antas system, Cambara do Sul, Rio Grande do Sul, Brazil, and septentrionalis RosA & COSTA, 1993 from a swamp near the C6rrego do Rancho fountainhead, Muncipio de Alto Araguaia, Mato Grosso, Brazil.

Authors' addresses: Manfred K. Meyer, Schwalheimer Hauptstrasse 22, D-61231 Bad Nauheim (Germany) Dr. Vollrad. Etzel, Hamburg-Amerika-Strasse 6, D-2?472 Cuxhaven (Germany)

www.pecescriollos.de

248 Zoo!. Abh. Mus. Tierkde. Dresden 51, Nr. 17 (2001)

In the following years two additional species of Cnesterodon from upper Rio Parana basin were described by LUCINDA & GARAVELLO (2000), namely hypselurus from Rio Cilada, Rio Paranapanenta drainage, Brazil, and omorgmatos from Rio das Torres, Rio Iguassu basin, Brazil.

ROSA & COSTA (1993) diagnosed Cnesterodon by nine so-called putative autapomorphies, and designated eight of them as unique among the subfamily Poeciliinae (PARENTI, 1981). Although we were not successful in corroborating the monophyly of Cnesterodon in all the described terms of ROSA & COSTA (1993), the monophyly for Cnesterodon herein is based on four derived characters.

The present paper describes one new freshwater species of the genus Cnesterodon (Poeci­liinae) from Northeastern Argentina.

Materials and methods

The new species of the genus Cnesterodon described in this paper is based on 22 adult males and females. The holotype and a series of paratypes have been deposited in the Staatliche Naturhistorische Sammlungen Dresden, Museum filr Tierkunde, and the Na­turmuseum Senckenberg, Frankfurt/M_ain. Comparative material examined: Cnesterodon decemmaculatus from Buenos Aires, Argen­tina; Cnesterodon carnegiei from Rio Iguassu basin, Brazil.

Measurements and counts follow standard practice (MILLER, 1948). Measurements were made by vernier callipers reading to 0.1 mm. The number of specimens for all counts is greater or equal to 10. The gonopodium length is measured from the origin to the tip of ray 3, excluding the distal appendix. The gill-raker count of the first arch includes any gill rakers in the angle of the gill arch. The last two rays in the dorsal and anal fin are counted as a single ray. Vertebral count includes the hypural plate as one vertebra. Nomenclature of the sensory canal system of the head follows the standard of GOSLINE (1949).

Abbreviations: AL= length of anal fin ; APL= distance anus to pectoral fin; A-CN = autapomorphy of Cnesterodon; BD =depth of body; CPL= length of caudal peduncle; CPD= depth of caudal peduncle; ED= diameter of eye; F =female ; GL =length of gono­podium; HL =length of head; HT = holotype; IOW = interorbital width; J =juvenile; MTD =fish collection of the Staatliche Naturhistorische Sammlungen Dresden, Museum ftir Tierkunde; PL =length of pectoral fin; PT= paratype; SMF =fish collection of the Na­turmuseum Senckenberg, Frankfurt/Main; SNL =length of snout; SL= standard length; S-CN = synapomorphy of Cnesterodon; TL =total length; VL =length of ventral fin.

Cnesterodon GARMAN, 1895

Di a g no sis : The genus Cnesterodon is characterized by the following derived characters: S-CN(l) reduction or absence of gonapophyses and usually the absence of a ligastyle, S-CN(2) retrorse claw of gonopodium ray 5 central with a spine-like outgrowth, S-CN(3) males with a dark triangular-shaped spot posterior to the gonopodium base, S-CN(4) sixth to ninth pleural ribs of males with wing-like extension, anteriorly curved and elongate.

Species included : brevirostratus, carnegiei, decemmaculatus, raddai sp. n., septen­trionalis, and with reservation hypselurus and omorgmatos.

Type species: C. decemmaculatus (JENYNS, 1843)

Cnesterodon raddai sp. n. (Figs. 1-4)

Material: Holotype: Male (MTD F 25416), SL= 16.6 mm, swamp near Resistencia, Rio Parana basin, Argentina; 09. September 1986, V. ETZEL et al. leg. Para types: 8 females, 3 males (MTD F 25417- 25427); 6 females , 2 males (SMF 28888); vicinity of Resistencia, Rio Parana basin, Argentina ; 20. June 1999, A. DIAZ (Brazil).

www.pecescriollos.de

M EYER & ETZEL: Description of Cnesterodon raddai sp. n. from Argentina 249

Fig. 1 (above): Cnesterodon raddai sp. n ., male, holotype (MTD F 25416). - Fig. 2 (below): Cnesterodon raddai sp. n. , female, paratype (MTD F 25418).

Etymology: The new taxon is named in honour of Prof. Dr. A. C. R ADDA, Wien (Austria). He was the first who recognized that this taxon represents an undescribed species of Cnesterodon (RADDA, 1979).

Diagnosis: Cnesterodon raddai sp. n. is a very small species of Cnesterodon (max. SL ea. 20 mm), which is distinguished from all other species of the genus by the following charac­ters: bony style at tip of gonopodium ray 3 tub- shaped and long, vs . longer in decemmacu­latus, gutter-shaped in carnegiei and septentrionaiis, and sinuous-shaped in brevirostratus; principal caudal rays 10-11, vs. 9- 10 in septentrionalis, 14-15 in carnegiei, decemmaculatus and brevirostratus; 1-4 short dark markings on body side, vs. 5-10 in decemmaculatus, 5-10 long and broad vertical dark markings in carnegiei, 6-11 long and slender vertical dark markings in septentrionalis, and 4- 13 irregularly shaped vertical markings in breviro­stratus. Cnesterodon raddai sp. n. is also distinguished by the following unique combination of characters: ligastyle absent and external teeth of jaws incisiform, vs. ligastyle absent and external teeth of jaws pointed in brevirostratus and carnegiei, ligastyle absent and external teeth of jaws canine-like in septentrionalis, ligastyle present and external teeth of jaws incisiform in decemmaculatus.

Description: Body slender, head long, 4.0 - 4.2 in standard length. Longitudinal scale series 30- 32 ; predorsal scale series 16-18; scale series around caudal peduncle 14 to 16. Number of vertebra 31- 33; pleural ribs 14; epipleural ribs 6- 7; in males ribs 6-8 anteriorly elongate,

www.pecescriollos.de

250 Zoo!. Abh. Mus. Tierkde. Dresdert 51, Nr. 17 (2001)

'~-----------------Fig. 3: Tip of the gonopodium of Cnesterodon raddai sp. n.

reaching pelvic girdle and subdistaljointed, distal forming a rod-shaped structure; ribs 6-10 in males distal with expansions. Gill rakers on the first arch 6-7. Teeth of upper and lower jaws unicuspid and recurved, those of the outer row incisiform and well separated, middle region most prominent not numerous, inner teeth numerous, small and pointed. Upper pharyngeal bones kidney-shaped. The teeth of the pharyngeal bone plates are small, pointed and recurved, each side with a total of> 60 and < 80 teeth. Lower pharyngeal bone (ceratobranchial 5) with a total of> 160 and< 210 curved unicuspid teeth , number of posterior rows 22- 24, number of medial rows 5-6, those of posterior rows higher than those directly in front. The two halves of the lower pharyngeal are heart­shaped and are close together along the midline. The pharyngeal arms are very short, the tips are spatulated and thorn-shaped. Ceratobranchial 4 without teeth, hypobranchial 4 absent. Supraorbital canal system weakly developed, formula: 3, 4a, 6-7; preopercular canal posteriorly forming a groove with 2-3 neuromasts, anteriorly represented by 2-4 neuro­masts ; preorbital canal represented by 3- 4 neuromasts; mandibular canal weakly develop­ed. Gonopodium long and slender, 2.4-2.5 in standard length; ray 3 broadly expanded and shorter as ray 4a, spine-like elements not present, base of ray 3 somewhat thickened, seg­ments broader than long; ray 4a much longer than ray 4p, ray 4a with a well developed spine-like distal segment, 4p with 4-5 paired serrae, ray 5a nearly as long as ray 5p, tip with a well developed claw, claw central with a spine-like outgrowth. Bony style at tip of gonopodium ray 3 long and arched, origin of the bony style between second and third sub-

Tab. 1: Measurements (in mm) of holotype and paratypes of Cnesterodon raddai sp. n.

TL SL HL SNL BD IOW GL ED APL CPL CPD PL VL AL HT{M) 20.40 16.60 4-30 1.20 3.60 1.20 6.40 l.30 1.70 6.00 2.10 2-50 1.30 PT(F) 24.30 19.40 5.10 1.40 4.70 1.90 1.50 5.30 6.50 2.40 3.40 1.80 3.30 PT{F) 23.80 l9.10 5.00 l.30 4.10 1.80 1.40 5.10 6.50 2.30 3.30 1.70 3-20 PT(F) 23.40 18.80 4.90 1.20 4.40 1.60 1.30 5.00 6.30 2.20 3.20 1.60 3.10 PT(F) 25.70 20.40 5.30 1.60 4.20 2.00 1.70 5.60 6.90 2.50 3.60 1.90 3.50 PT(F) 24.40 19.50 5.10 1.40 4.00 1.90 1.60 5.50 6.60 2.40 3.40 1.80 3.40 PT(F) 24.90 19.70 5.10 1.40 4.10 1.80 1.60 5.40 6.70 2.40 3.30 1.80 3.40 PT(M) 21.20 16.80 4.40 1.10 3.70 1.20 6.60 l.30 1.70 6.10 2.10 2.40 1.40 PT{F) 24.80 19.70 5.20 1.40 4.10 1.90 1.60 5.50 6.70 2.40 3.40 1.70 3.50 PT{F) 24.30 19.40 5.20 1.30 4.00 1.90 1.50 5.50 6.60 2-30 3.30 1.70 3.40 PT(M) 16.90 13.80 3.60 0.90 3.30 1.00 5.80 1.10 1.40 5.10 1.80 2.10 1.20 PT(M) 18.80 15.30 4.00 1.10 3.40 1.10 6.20 1.20 1.50 5.50 1.90 2.40 l.30

www.pecescriollos.de

MEYER & ETZEL: Description of Cnesterodon raddai sp. n. from Argentina 251

Fig. 4: Cnesterodon raddai sp. n., aquarium specimen, male.

distal segment of ray 4a, membranous tissue of bony style well developed; rays 6-7 very thickened distally, ray 7 shorter as ray 6; both rays curved dorsally. The gonopodial suspensorium is without gonapophyses. A ligastyle is not present. Gonac­tinostal complex has eight gonactinosts without outgrows, gonactinosts 2- 4 fused to a plate and with small and roundecrsuperior lateral wings, inferior lateral wings rounded and well developed. Fins well developed; dorsal (6- 7 rays) small, origin in both sexes behind the insertion of anal fin ; caudal 22 to 24 (10-11 branched) rays, anal of female small (rays 9); pectoral long (10-11 rays), in males very long reaching over the ninth rib; ventral fin (3- 6 rays), in females 6, in males 3, the first two and the last ray stunted and forming naps, in females ventral fins reaching over the anus and in males reaching to the base of the gonopodium.

Colouration: Males and females with no well pronounced sex-specific colouration. Ground colour of body of adult females and males greyish silver; body side with one series of 1-4 vertical bars , which are broad and most prominent on the rear body half along longitudinal region, the last 1- 2 bars usually rounded; males usually with a ventral dark spot behind the gonopodium base. Fins and gonopodium hyaline.

Comparison and relationships: On the basis of synapomorphies, Cnesterodon raddai sp. n. are unequivocally attached to the genus Cnesterodon. The derived characters of Cnestero­don are given in the generic diagnosis. Synapomorphies between Cnesterodon raddai sp. n. and Cnesterodon decemmaculatus: S- CN(5) subdistal segments of gonopodium ray 3 much longer than high; S-CN(6) bony gonopodium style tub-shaped; S-CN(7) origin of bony gonopodium style between the second and third or third and fourth segment of gonopodium ray 4a. Synapomorphies between Cnesterodon raddai sp. n. , Cnesterodon decemmaculatus and Cnesterodon brevirostratus: S-CN(8) bony style at tip of the gonopodium without a ventral projection; S-CN(9) dark markings on side of body short, not reaching dorsal and ventral profile. In comparison to Cnesterodon decemmaculatus (including omorgmatos), the new species is further distinguished by a lower number of dorsal fin rays, 6-7 vs . 7- 8 (rarely 9) ; lower number of ventral fin rays in males, 3 vs. 4- 5; higher number of ventral fin rays in females, 6 vs . 4-5; lower number of caudal fin rays, 23 vs. 25- 27; lower number of epipleural ribs, 6- 7 vs. 7-8; less membranous tissue of bony style of the gonopodium, vs . well developed membranous tissue.

www.pecescriollos.de

252 Zoo!. Abh. Mus. Tierkde. Dresden..51, Nr. 17 (2001)

In contrast to Cnesterodon carnegiei (including hypselurus), the new taxon shows further a lower number of dorsal fin rays , 6-7 vs. 7-8; higher number of ventral fin rays in females, 6 vs. 5; lower number of caudal fin rays, 23 vs. 25-29; lower number of epipleural ribs, 6- 7 vs . 10-12; bony style at tip of the gonopodium without a ventral projection, vs. ventral projection of bony style present; gonactinosts 2-4 of gonopodial suspensorium system fused to a plate, vs. not fused to a closed plate (not known for hypselurus); inferior wings of gonactinosts 2-4 rounded, vs. pointed dorsally (not known for hypselurus). In comparison to brevirostratus, C. raddai sp. n. is further distinguished by a lower num­ber of dorsal fin rays, 6-7 vs. 7- 8; lower number of ventral fin rays in males , 3 vs . 4 ; higher number of ventral fin rays in females, 6 vs. 5; lower number of caudal fin rays , 23 vs. 28-29; lower number of epipleural ribs, 6-7 vs. 7-14; pointed snout, vs. blunt snout. In comparison to Cnesterodon septentrionalis, the new species is further distinguished by a lower number of ventral fin rays in males , 3 vs. 4; higher number of ventral fin rays in females, 6 vs. 5; higher number of longitudinal scale series, 30-32 vs. 25-26; bony style at tip of the gonopodium without a ventral projection, vs. ventral projection of the bony style present.

Habitat and associates: Cnesterodon raddai sp. n. is restricted so far as known to central Rio Parana basin in the north of Argentina, but it would not be surprising to find the new species also further north in the region of Rio Paraguay basin. The turbid, still water is 3 to 50 cm deep and 2.0 m wide at the point of collection. The ground is predominantly of mud. The edges of the swamp are overgrown with grass, Sagittaria and not identified swimming plants. Cnesterodon raddai sp. n. is the only species of fishes found in that area. Cnesterodon raddai sp. n. was collected in September 1986. At the type locality water tem­peratures varied from 20°C to 22°C, pH 7.0, GH dH < 1.

Acknowledgements

The authors gratefully acknowledge the collaboration and assistance of the following persons : Herr H. ZETZSCHE, Naturmuseum Senckenberg, Frankfurt (M.) ; Frau I. RADDA, Wien; Herr Dr. K. Busse, Museum A. Koenig, Bonn; Frau K. MEYER, Bad Nauheim; Frau Dr. M. ETZEL, Cuxhaven; Frau C. EHRICH (former Tarija, Bolivia), and Herr R. EHRICH, Berlin; Herr Kees DE JONG, Hoorn; Herr Dr. A. ZARSKE, Museum fur Tierkunde Dresden; Herr R. HAASE, Stuhr; Herr K. W. FEHLAU, Gummersbach.

References

GOSLINE, W. A. (1949): The sensory canals of the head in some cyprinodont fishes, with particular reference to the genus Fundulus. - Occas. Papers Mus. Zoo!. Univ. Michi­gan 519: 1-17.

LUCINDA, P.H. F. & J. C. GARAVELLO (2000): Two new species of Cnesterodon GARMAN, 1895 (Cyprinodontiformes: Poeciliidae) from the upper Rio Parana drainage . - Comun. Mus. Cienc. Tecnol. PUCRS, Ser. Zoo!. 13: 119-138.

MILLER, R.R. (1948): The cyprinodont fishes of the Death Valley system of eastern Califor­nia and southwestern Nevada. - Misc. Puhl. Mus. Zoo!. Univ. Michigan 68: 1-155.

PARENTI, L. R. (1981): A phylogenetic and biogeographic analysis of Cyprinodontiform fishes. - Bull. Am. Mus. Nat. Hist. 168, art. 4: 335-557.

RADDA, A. C. (1979): Die Tribus Cnesterodontini. Eine Ubersicht. - Aquaria 26: 129- 134. ROSA, R. S. & W. J .E. M. COSTA (1993): Systematic revision of the genus Cnesterodon (Cy­

prinodontiformes: Poeciliidae) with the description of two new species from Brazil. - Copeia (3): 696-708.

(Received on July 25, 2001)

www.pecescriollos.de