Hemigrammus tridens is a small characid described by Eigenmann (in Eigenmann & Ogle, 1907) from Paraguay River, in the country Paraguay. The species has a conspicuous trident-shaped caudal spot, few perforated lateral line scales, scales on the caudal fin, and two pentacuspidate teeth in the outer series of the premaxilla. Hemigrammus tridens is found in the Paraná River basin of both, Argentina and Paraguay. The records from Argentina are the first for this species in the country. Comments on the type series are added.Fil: Azpelicueta, Maria de Las M.. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados; ArgentinaFil: Koerber, Stefan. Universitat Dusseldorf; Alemani

Azpelicueta, Maria de Las M.

Koerber, Stefan

Revue suisse de zoologie

Fig. 5. Map showing the three collecting sites of Hemigrammus tridens in the Paraná Basin. Circle: Paraguay (Country), Güyraugua River; star: Argentina, Corrientes, San Cosme; triangle: Argentina, Chaco, Puerto Tirol.Published as part of Azpelicueta, María de las Mercedes & Koerber,  Stefan, 2017, Hemigrammus tridens Eigenmann (Characiformes, Characidae): first records of a small tetra from the Paraná River basin, pp. 67-71 in Revue suisse de Zoologie 124 (1) on page 70, DOI: 10.5281/zenodo.32266

Azpelicueta, María de las Mercedes

Koerber,  Stefan

ZENODO

Fig. 5 in Hemigrammus tridens Eigenmann (Characiformes, Characidae): first records of a small tetra from the Paraná River basin

Hemigrammus tridens is a small characid described by Eigenmann (in Eigenmann & Ogle, 1907) from Paraguay River, in the country Paraguay. The species has a conspicuous trident-shaped caudal spot, few perforated lateral line scales, scales on the caudal fin, and two pentacuspidate teeth in the outer series of the premaxilla. Hemigrammus tridens is found in the Paraná River basin of both, Argentina and Paraguay. The records from Argentina are the first for this species in the country. Comments on the type series are added.Facultad de Ciencias Naturales y MuseoConsejo Nacional de Investigaciones Científicas y Técnica

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<i>Hemigrammus tridens</i> Eigenmann (Characiformes, Characidae): First records of a small tetra from the Paraná River basin

Azpelicueta, María de las Mercedes, Koerber,  Stefan (2017): Hemigrammus tridens Eigenmann (Characiformes, Characidae): first records of a small tetra from the Paraná River basin. Revue suisse de Zoologie 124 (1): 67-71, DOI: 10.5281/zenodo.32266

ISSN 0035-418INTRODUCTIONThe basin of the Río de la Plata comprises three large rivers: Paraná, Paraguay, and Uruguay. There are several tetras, e.g., Hemigrammus ulreyi (Boulenger, 1891) or Hyphessobrycon elachys Weitzman, 1985, which live in environments of Paraguay and Paraná Rivers. Hemigrammus tridens is a small characid described by Eigenmann (in Eigenmann & Ogle, 1907) based on two specimens from the arroyo Pypucú which is a tributary of the Río Apa (Eigenmann & Kennedy, 1903), Paraguay River basin, in the country Paraguay. Géry (1977) divided the genus Hemigrammus in several artifi cial groups; one of them is the Hemigrammus-tridens-group, based on the presence of a caudal spot, usually a longitudinal band or line along body and the absence of a humeral spot. Britski et al. (1999) mentioned its presence among the ichthyofauna of the Pantanal, Paraguay River basin (Mato Grosso, Brazil), and it was cited in several papers, usually, associated to descriptions of species: Uj & Géry (1989), Zarske & Géry (2002, as Hyphessobrycon tridens), Bertaco & Carvalho (2005), and Carvalho et al. (2010). For other collecting localities see Ota (2010) who included H. tridens in her thesis about the species of the genus Hemigrammus Gill, 1858 in the Paraguay River basin. The objective of this short contribution is to record this small tetra found at environments of the Paraná River, in the Provinces of Corrientes and Chaco, Argentina, and to report its presence in the Paraná River basin of the country Paraguay. The records from Argentina are the fi rst for this species in the country.MATERIAL AND METHODSSpecimens were fi xed in formaldehyde and subsequently transferred to ethanol 70%. Measurements were taken following Fink & Weitzmann (1974), and are indicated in Table 1. Counts indicate the value followed by the number of specimens between brackets. Institutional abbreviations follow Sabaj-Pérez (2016). Material examinedParaguay River basin:CAS 58609, photograph of holotype, Hemigrammus tridens Eigenmann, 1907.MHNG 2544.071, 3 specimens, 15.5-18.2 mm SL, Paraguay, Concepción, Riacho El Postillón, 6 km from Puerto Max, coll.: F. Baud, C. Dlouhy, V. Mahnert, J.-L. Perret, C. Vaucher, B. Jacquet, and A. Colman. October 20, 1979. Paraná River basin: MHNG 2179.022, 1 specimen, 19.5 mm SL, Argentina, Chaco, Puerto Tirol, affl uent of a lagoon, coll.: A. Pira.MHNG 2678.025, 5 specimens (3 measured, 1 female, 3 males), 16.5-17.3 mm SL, Argentina, Corrientes, Depto. San Cosme, RN 12, km 1072, 27°22’34”S-58°23’47”W (taken from Google Earth), permanent lake in the premises of Olho-Porá, coll.: S. Koerber and J.O. Fernández Santos, September 23, 1995.Revue suisse de Zoologie (March 2017) 124(1): 67-71Hemigrammus tridens Eigenmann (Characiformes, Characidae):fi rst records of a small tetra from the Paraná River basinMaría de las Mercedes Azpelicueta1 & Stefan Koerber21 Facultad de Ciencias Naturales y Museo-Conicet, UNLP, Paseo del Bosque, 1900 La Plata, Argentina. E-mail: azpelicueta@gmail.com2 Friesenstr. 11, 45476 Muelheim, Germany. E-mail: pecescriollos@koerber-germany.deAbstract: Hemigrammus tridens is a small characid described by Eigenmann (in Eigenmann & Ogle, 1907) from Paraguay River, in the country Paraguay. The species has a conspicuous trident-shaped caudal spot, few perforated lateral line scales, scales on the caudal fi n, and two pentacuspidate teeth in the outer series of the premaxilla. Hemigrammus tridens is found in the Paraná River basin of both, Argentina and Paraguay. The records from Argentina are the fi rst for this species in the country. Comments on the type series are added.Keywords: Hemigrammus tridens - Paraná River basin - Argentina - Paraguay - complementary description.Manuscript accepted 24.11.2016DOI: 10.5281/zenodo.32266668 M. M. Azpelicueta & S. KoerberOrigin of dorsal fi n nearer caudal fi n than eye; dorsal fi n ii,9 rays (9). Pectoral fi n falling short anal-fi n origin or surpassing it in males, pectoral fi n with i,10(3),11(6) rays. Pelvic fi n with i,7 rays, surpassing anal fi n origin; pelvic-fi n origin in a vertical through second or third scale anterior to dorsal-fi n origin; pelvic fi n with hooks in all branched rays. Anal fi n short with iii-iv,15(2),16(3),17(4) rays; its origin in a vertical through second scale posterior to last dorsal-fi n ray insertion; anal fi n of males with anterior lobe very well developed, formed by six or seven branched rays. Hooks developed from last unbranched anal-fi n ray to middle anal-fi n length in most specimens (Fig. 3) although one specimen with hooks until last rays. Anal-fi n hooks large, located one pair per segment, up to 12 in a ray, in both branches, and decreasing in number backward. Snout short; eye larger than snout; mouth terminal, at horizontal through upper half of eye. Maxilla long, surpassing anterior margin of eye. Two maxillary teeth, pentacuspidate. Premaxilla with an inner series of fi ve teeth and an outer series formed by two teeth, all of them pentacuspidate (Fig. 4). Dentary with three or four large teeth followed by three to fi ve small teeth. Three or four fi rst teeth pentacuspidate, CI-FML 7107 (ex MHNG 2742.079), 8 specimens, 15.0-16.9 mm SL, Paraguay, Caaguazú, small tributary of Río Güyraugua, Paraná River basin, South of the route between Asunción and Ciudad del Este, coll.: S. Fisch-Muller, C. Dlouhy and V. Mahnert, July 11, 1990. MLP 10917 (ex MHNG 2742.079), 2 specimens, 16.4-17.2 mm SL, all collecting data same as of previous. MHNG 2494.019, 2 specimens, 17.4-18.4 mm SL, Paraguay, Itapuá, arroyo Pirayu-í, coll.: C. Weber and C. Dlouhy, October 10, 1986. RESULTSHemigrammus tridens (Figs 1-2) has a conspicuous caudal-fi n spot as a “jet-black band” across the end of the caudal peduncle and caudal fi n. It extends forward, forming a blunt median point and backward along edge of caudal-fi n rays also, especially marked in the base of middle caudal-fi n rays. Thin lateral band along body. Humeral spot absent or present as a very faint spot of scattered chromatophores.Table 1. Measurements of nine specimens of Hemigrammus tridens from the Paraná River basin in Argentina and Paraguay. Güyraugua N=5. San Cosme N=3. Puerto Tirol N=1.Hemigrammus tridens Paraguay Argentina ArgentinaGüyraugua San Cosme Puerto Tirolmin max min maxSL 15.00 16.90 16.50 17.30 19.50Percentage in SLpredorsal length 1.67 1.84 2.2 2.4 1.86prepelvic length 1.75 2.01 1.76 1.84 1.88preanal length 1.48 1.56 1.48 1.59 1.47maximum body depth 2.78 2.95 2.89 3.00 3.07head length 3.16 3.25 3.05 3.11 3.36anal-fi n base 3.78 3.9 4.12 4.2 3.82pectoral length 5.0 3.96 4.17 4.71 4.02ventral length 3.95 4.84 4.24 4.71 4.43pelvic fi n/anal fi n length* 2.8 3.05 2.73 2.84 2.63anal fi n/caudal rays length** 2.56 2.67 2.63 2.74 2.56Percentage in head lengthsnout 3.69 4.08 3.7 3.92 3.6eye 2.00 2.22 2.29 2.54 1.98interobital distance 3.06 3.69 2.94 3.17 3.05postorbital distance 2.04 2.4 2.1 2.43 2.14  *length between pelvic-fi n origin and anal-fi n origin; **length between anal-fi n origin and middle caudal-fi n rays.Hemigrammus tridens in  Paraná River basin 69remaining teeth tricuspidate or conic. Number of lateral line scales: 30(5) or 31(4); perforated scales of lateral line: 3(1),4(3),5(2),6(3); transverse scales: 5/3-3.5(3) or 5/3.5(6). DISCUSSIONEigenmann & Ogle (1907) commented that species of Hemigrammus Gill, 1858 differ from Astyanax Baird & Girard, 1854, by the incomplete lateral line. Nonetheless, the diagnosis of the genus Hemigrammus following Eigenmann (1918) is based on the presence of an incomplete lateral line, caudal fi n scaled, premaxillary teeth in two rows, and maxillary teeth lacking or reduced in number, restricted to the upper portion of the bone, a defi nition still in usage. Ota (2010) considered that the humeral spot of H. tridens – if present – is only a faded concentration of chomatophores in the study of the genus Hemigrammus from Paraguay Basin. The genus, considered today within Pristellinae (Géry & Boutière, 1964; Eschmeyer et al., 2016), contains about 60 species. Uj & Géry (1989) discussed the inclusion of H. tridens in the genus because they could not fi nd scales in the caudal fi n. However, in the material examined, few specimens from the Paraná river basin have scales in the caudal fi n. The small scales of the caudal fi n fall down easily. Ota (2010) examined a large number of specimens, many of them without caudal-fi n scales, considering that those small scales may be lost. Hemigrammus tridens was so far only known from several localities in the Paraguay River basin. The specimens examined belong to three collecting sites of the Paraná River basin, downstream from its confl uence Figs 1-2. (1) Hemigrammus tridens, MHNG 2678.025, 17.3 mm SL, male. (2) Detail of the caudal spot. Scale bars = 1 mm.Figs 3-4. (3) Hemigrammus tridens, MHNG 2678.025, 17.3 mm SL, male, anal fi n with hooks. (4) Hemigrammus tridens, CI-FML 7107, 17.0 mm SL, female, premaxilla and maxilla. Scale bars = 1 mm.70 M. M. Azpelicueta & S. Koerberwith the Paraguay River (Fig. 5). Güyraugua river is a tributary of Monday river in the country Paraguay. Puerto Tirol is located on the coast of Paraná River in Argentina. The environment in which H. tridens was collected close to San Cosme is a permanent lake, more than 1 m deep, with profuse vegetation and abundant wood on substrate (Fig. 6). In this habitat the following species were found: Aphyocharax nattereri, Hyphessobrycon elachys, H. eques, H. igneus, H. luetkenii, Moenkhausia dichroura, Serrapinnus calliurus, Pyrrhulina australis, Apistogramma borellii, Cichlasoma dimerus, and Laetacara dorsigera (captured in December 1994 and/or September 1995).COMMENTS ON THE STATUS OF THE TYPE SPECIMENSEigenmann & Ogle (1907) described Hemigrammus tridens based on two specimens, designated “Type” and “Cotype”, from the Pypucú stream in Paraguay, being then deposited both at the Indiana University collection (IU 11262). These specimens are today housed at the California Academy of Sciences in the lots CAS 58609 (holotype) and CAS 61474 (paratype). This type status is supported by the article 72.4.6 of the International Code of Zoological Nomenclature (1999). A decade later, Eigenmann (1918) mentioned a third specimen from the same locality which was not included in the original description. This additional specimen is also still available in San Francisco (CAS 61475) and the CAS online database states that it was initially also from lot IU 11262 with the remark as “collected w/ type series, but non-type” because the article before mentioned expressively excluded other specimens not nominated as types. Eschmeyer et al. (2016) list a potential additional paratype specimen from the collection of Zoologisches Museum Berlin as “?ZMB 17146 [from Eigenmann] (1) Corumba”. This specimen is available in the ZMB-collection. The respective label states “Typus”, probably noted on the label by August Brauer (Peter Bartsch, pers. comm.), director of ZMB from 1906 to 1917. Also, the label provides information about Eigenmann and Anisits as donators, Anisits as collector and 328 as Anisits’ collector’s fi eld number. The ZMB holds yet another specimen (ZMB 17258) from Corumbá with Anisits’ collector’s number 305a. This one is not labeled as type. Eigenmann et al. (1907) have seen specimens from the afore mentioned collector’s lots, but they did not identify the specimens as Hemigrammus tridens. In this paper, specimens from Anisits’ lot 328 are mentioned as Hemigrammus ulreyi from Corumbá and from lot 305, as small individuals similar to Moenkhausia agassizii. As both papers were published in 1907, one would expect that Eigenmann had recognized additional specimens of Hemigrammus tridens while determining these lots.Anisits spent nearly his whole professional life in Paraguay; around 1907 he moved to Berlin where he passed away in 1911 (Zarske, 2012). One year after his death, a note was published (Anisits, 1912) in which he confi rmed that he did not send all material to Eigenmann but retained what he considered duplicates for his own further studies and that he donated those to the ZMB-collection. It is a mandatory condition for types that the author/s of a new species has determined the specimens. Fig. 5. Map showing the three collecting sites of Hemigrammus tridens in the Paraná Basin. Circle: Paraguay (Country), Güyraugua River; star: Argentina, Corrientes, San Cosme; triangle: Argentina, Chaco, Puerto Tirol.Fig. 6.  Permanent lake close to San Cosme (27°22’34”S-58°23’47”W), RN 12, km 1072,  Depto. San Cosme, Corrientes, Argentina. Hemigrammus tridens in  Paraná River basin 71Considering the article 72.4.6 the specimens in the Collection of the ZMB are not type material. Also, article 72.4.1.1 does not apply in this case.ACKNOWLEDGMENTSAuthors thank S. Fisch-Muller for the donation of specimens from Paraguay, A. Vanegas-Ríos and S. Gouiric-Cavalli for the photographs of the specimen, the late J.O. Fernández Santos for his expertise in the fi eld, F. Carvalho for several suggestions on the manuscript, P. Bartsch for information about the material in ZMB. REFERENCESAnisits J.D. 1912. Ein neues Vorkommen von Gyrinurus ba trachostoma Mir. Ribeiro. Sitzungsbericht der Gesell-schaft naturforschender Freunde zu Berlin 9: 465-468.Bertaco V.A., Carvalho T.P. 2005. New characid fi sh, Hemi-grammus skolioplatus (Characiformes: Characidae) from upper Rio Tapajós drainage, central Brazil. Comunicações do Museu de Ciências e Tecnologia da PUCRS 18(2): 141-150.Britski H.A., Silimon K.Z.S., Lopes B.S. 1999. Peixes do Pan-tanal. 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