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Studies on Neotropical Fauna and Environment Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/nnfe20 On the species of Ellis, 1912, translucent sand‐dwelling Gymnotid fishes from (Pisces, Cypriniformes, Gymnotoidei) H. Nijssen a , I. J. H. Isbrücker b & J. Géry c a Curator of Fishes, Dept. of Ichthyology, Zoologisch Museum, Plantage Middenlaan 53, Amsterdam, The Netherlands b Dept. of Ichthyology, Zoologisch Museum, Plantage Middenlaan 53, Amsterdam, The Netherlands c Argentonesse, Castels, Saint‐Cyprien, France Published online: 21 Nov 2008.

To cite this article: H. Nijssen , I. J. H. Isbrücker & J. Géry (1976): On the species of Gymnorhamphichthys Ellis, 1912, translucent sand‐dwelling Gymnotid fishes from South America (Pisces, Cypriniformes, Gymnotoidei), Studies on Neotropical Fauna and Environment, 11:1-2, 37-63 To link to this article: http://dx.doi.org/10.1080/01650527609360496

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On the Species of Gymnorhamphichthys Ellis, 1912, Translucent Sand-dwelling Gymnotid Fishes from South America (Pisces, Cypriniformes, Gymnotoidei)

by

H. Nijssen, I. J. H. Isbrücker & J. Géry (Amsterdam - St. Cyprien)

INTRODUCTION Gymnorhamphichthys hypostomus was originally described by Ellis (in Eigen- mann, 1912: 436-437), based on the holotype, 215 mm total length, from San Joaquin, Rio Guaporé system, Bolivia. There were ten paratypes, 75 to 180 mm total length. Four paratypes were collected in the Rio Guaporé system (Rio Mamoré, Bastos, and Maciel), five are from the Essequibo river system, (formerly British-) Guyana (Konawaruk and Tumatumari), and one from the upper Rio Parana (Puerto Bertoni). The holotype was figured in 1913 (Ellis, pi. 23, fig. 2), and the head of another specimen, with a much shorter snout, in the dendrogram (Ellis, loc. cit., pi. 15). Urumara rondoni was originally described by A. de Miranda Ribeiro (1920: 6-7) from the single holotype, 140 mm total length, from the Rio Guaporé system, Rio 17 de Fevereio, a tributary of Rio Cautario. It was figured for the first time by Curra & P. de Miranda Ribeiro (1961, fig. 1). Gymnorhamphichthys hypostomus petiti was originally described and figured by Géry & Vu (1964: 486-492, pi. 1). The holotype and 21 paratypes, 73 to 122 mm total length, are from the upper Rio Araguaia. The authors suggested a synonymy of Gymnorhamphichthys with Urumara, but as they had not examined type material of either, verification of this hypothesis was im- possible. The contrary opinion, i.e. that the two genera are distinct, was expressed by Fernandez-Yépez (1968?: 33). We were faced with this controversy when we started our study of 158 Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 polymorphic specimens (one is shown in fig. 14). These were collected during recent expeditions to Surinam (the Brokopondo Research Project, 1964-1967, sponsored by the Foundation for Scientific Research in Surinam and the Netherlands Antilles, with the financial aid of the Netherlands' Foundation for the Advancement of Tropical Research). Completion of our study was made possible by the help of many colleagues, who provided addi- tional material from Guyana, Venezuela, Colombia, Bolivia, and Brazil, 38 H. NÜSSEN et al.

including the type material of Gymnorhamphichthys hypostomus, Urumara rondoni, and Gymnorhamphichthys hypostomus petiti. We have considered all the examined samples as representatives of two species: Gymnorhamphichthys hypostomus (known from six specimens), and Gymnorhamphichthys rondoni (all other specimens), treating Gymno- hypostomus petiti as a junior synonym of Gymnorhamphichthys rondoni. We are grateful to the following persons for the loan of material and/or for information: Dr M. Boeseman and Dr G. F. Mees, Rijksmuseum van Natuurlijke Historie, Leiden (RMNH), Dr J. E. Böhlke and Mr W. G. Saul, Academy of Natural Sciences, Philadelphia, Penn. (ANSP), Dr H. A. Britski, Museu de Zoologia, Universidade de Sâo Paulo (MZUSP), Mrs M. M. Dick and Dr T. R. Roberts, Museum of Comparative Zoology, Cambridge, Mass. (MCZ), Dr W. N. Eschmeyer and Miss P. Sonoda, California Academy of Sciences, San Francisco, Calif. (CAS), Dr J. P. Gosse and Mr E. Walschaerts, Institut Royal des Sciences Naturelles de Belgique, Brussels (IRScNB), Dr P. H. Greenwood, Mrs Dr R. H. Lowe-McConnell, and Mr G. Howes, British Museum (Natural History), London (BMNH), Dr H. A. Knôppel, Max- Planck-Institut für Limnologie, Pion (MPIL), Dr H. Travassos, Museu Nacional, Rio de Janeiro (MNRJ), Dr S. H. Weitzman and Mr W. L. Fink, National Museum of Natural History, Washington D.C. (USNM), Dr L. P. Woods, Field Museum of Natural History, Chicago, 111. (FMNH). The material indicated by GSC is located in the personal collection of the third author at Saint-Cyprien, France. Mr G. Howes (BMNH) kindly read the manuscript. The photographic illustrations were made by Mr L. A. van der Laan, Instituut voor Taxonomische Zoologie (Zoologisch Museum), Amster- dam (ZMA). Figure 15 was made by Dr J. P. Gosse. A visit to Cambridge, Mass, was made possible by a grant of the Netherlands Organization for the Advancement of Pure Research (Z.W.O.) to the first author.

HISTORICAL ACCOUNT AND CONCLUSIONS Ellis (in Eigenmann, 1912: 436) recognized Gymnorhamphichthys as a new , stating: "Anterior portion of sides without scales, but other characters much the same as in Rhamphichthys". Describing the single species in this genus, Gymnorhamphichthys hypostomus, Ellis (loc. cit.: 437) remarks: "... anus on or a little behind the vertical from the posterior margin of the eye...", "... snout produced, straight and tubular, its length varying in a direct Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 ratio with that of the body...", and: "The snout is also subject to variation, growing longer in the larger fish, hence the rather large range of the measurements in which the length of the head or snout figure...". Ellis gives for the snout in head ratio a variation of 1.6 to 2.0. We examined the holotype and nine paratypes of Gymnorhamphichthys hypostomus (one of the three paratypes of Tumatumari, CAS (IUM 12613) is missing) and found that Ellis' statement regarding the position of the anus must GYMNORHAMPHICHTHYS SPECIES FROM SOUTH AMERICA 39

have been based on the holotype and on the two paratypes from Konawaruk only, which have the anal pore situated on the vertical extending from the eyes. In the remaining paratypes the anal pore is situated more posteriorly, viz., in the specimens from Upper Rio Parana and from Tumatumari (the second available paratype from Tumatumari is damaged) between gill opening and a vertical extending from the pectoral fin base; in the specimen from Rio Mamoré just in front of the vertical from the pectoral fin base; and in the specimens from Bastos and Maciel at the vertical from the pectoral fin base. A. de Miranda Ribeiro (1920: 6), apparently unaware of the existence of the genus Gymnorhamphichthys, described a new genus, Urumara, stating: "Faciès de Rhamphichthys. Dorsal adipose inexistente, caudal idem, em seu logar uma cauda terete, filiforme. Anus entre as peitoraes; anal posterior â estas." A more complete generic diagnosis of Urumara was given by Curra & P. de Miranda Ribeiro (1961: 474), reading: "Cuerpo totalmente desnudo; origen del orificio anal entre las verticales que pasan por el borde posterior del opérculo y la base de las pectorales." We examined the single holotype of Urumara rondoni, sent to Amsterdam by Dr H. Travassos. The specimen (fig. 5) is now in bad condition (not well preserved and the snout bent). The posterior portion of the fish is, however, scaled. The anal pore is just in front of a vertical extending from the pectoral fin base. In these characters the specimen agrees with the paratype of Gymnorhamph- ichthys hypostomus from Rio Mamoré. When describing Urumara rondoni, A. de Miranda Ribeiro did not refer to Gymnorhamphichthys hypostomus. Curra & P. de Miranda Ribeiro (loc. cit.: 475) compared Urumara rondoni with Ellis' description of Gymnorhamphichthys hypostomus, stating: "Similar a Rhamphichthys y Gymnorhamphichthys de los cuales, difiere fundamental- mente en la posicion del orificio anal y en la escamacion." It appears that they did not examine type material of Gymnorhamphichthys hypostomus. There are numerous very small scales present on the posterior part of the body in both Gymnorhamphichthys hypostomus and in Urumara rondoni. The minute scales become clearly visible in preserved specimens after having been dried a little. It is apparent that all (re-examined) paratypes of Gymnorhamph- ichthys hypostomus belong to the same species as represented by the holotype of Urumara rondoni. As there is no evidence to support generic status for Urumara, it is considered a synonym of Gymnorhamphichthys. Thus the paratypes of G. hypostomus are re-designated as G. rondoni. Géry & Vu (loc. cit.: 488) distinguished Gymnorhamphichthys hypostomus petiti from the nominate subspecies mainly by the differences in the position of the anus and in the number of anal fin rays, stating: "Les deux Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 différences essentielles, outre quelques proportions qui seront discutées plus loin, résident dans la position de l'anus et le nombre des rayons de l'anale." Géry & Vu did not examine a paratype of the nominate subspecies having the same anal position as in their subspecies Gymnorhamphichthys hypostomus petiti. They admit not having examined adult specimens and state (loc. cit.: 489): „Ellis (1913) précise que l'anus, chez la sous-espèce nominale, se trouve situé sur une verticale passant par l'oeil. Aucun de nos exemplaires n'a l'orifice 40 H. NIJSSEN et al.

anal placé aussi en avant, mais il faut faire remarquer que le plus grand (holotype, 87 mm de longueur standard) n'est certainement pas adulte...". Concerning the fewer anal fin rays in their subspecies, they remark (loc. cit.: 489): „Le nombre des rayons de l'anale, qui ne nous paraît pas être influencé par la longueur des spécimens est très nettement inférieur à celui de la sous- espèce nominale." The somewhat shorter snout and head in Gymnorhamphichthys hypostomus petiti are apparently due. to the fact that this subspecies is based on juvenile specimens only, which are indistinguishable as far as these characters are concerned from several paratypes of Gymnorhamphichthys hypostomus (= Gymnorhamphichthys rondonî) of the same size. Comparing Gymnorhamphichthys hypostomus petiti with the redescription of Urumara rondoni, Géry & Vu (loc. cit.: 492) doubted the validity of the latter genus and species. After discussing the differences mentioned by Curra & P. de Miranda Ribeiro concerning scalation, anus position, height of the body, and the angle of the snout with the axis, they state: "II y a donc une certaine probabilité pour que A. de Mirando Ribeiro (1920) ait décrit comme genre nouveau un jeune de G. hypostomus, d'autant plus que les localités typiques coïncident."

The holotype of Gymnorhamphichthys hypostomus and five specimens from Colombia differ from the remaining 324 specimens examined in the higher number of anal fin rays: more than 180, rather than less than 174. They also have a smaller eye, while five of these six specimens show distinct midlateral dark blotches, absent in the other 324 specimens. The remaining 324 specimens (including 9 paratypes of Gymnorhamphichthys hypostomus, the holotype of Urumara rondoni, and the holotype and 20 paratypes of Gymnorhamphichthys hypostomus petiti) represent a second, polymorphic species of Gymnorhamphichthys, viz. Gymnorhamphichthys rondoni (A. de Miranda Ribeiro, 1920).

Gymnorhamphichthys Ellis, 1912 Gymnorhamphichthys Ellis, in Eigenmann, 1912: 436 (original diagnosis; type-species, by original monotypy, Gymnorhamphichthys hypostomus Ellis, 1912). Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 Urumarä Alipio de Miranda Ribeiro, 1920:6-7 (original diagnosis; type-species, by original mönotypy, U[rumara\ rondoni Alipio de Miranda Ribeiro, 1920). Urumaria; Fowler, 1951: 419 (misspelling). Urumara; Géry & Vu, 1964: 485 et seq. (correct spelling).

The following characters are used in this study (fig. 1, table 1): GYMNORHAMPHICHTHYS SPECIES FROM SOUTH AMERICA 41

an - the distance measured from tip of snout to centre of anal pore or to anterior tip of anal papilla, hi - the head length, measured from tip of snout to highest point of the gill opening. la - length of anal fin. pal - the pre-anal fin length, measured from tip of snout to base of first anal fin ray. si - the standard length, measured from tip of snout to base of last anal fin ray. sn - the snout length, measured from tip of snout to anterior rim of eye. tl - the total length, measured from tip of snout to tip of caudal filament.

The abbreviation N indicates the number of specimens.

Fig. 1. Diagram of a Gymnorhamphichthys showing methods of measurement (explanation in text).

Gymnorhamphichthys hypostomus Ellis, 1912 (figs. 2-4a, 6-11, tables 1-2) Gymnorhamphichthys hypostomus Ellis, in Eigenmann, 1912:436-437 (original description; holotype only; type locality: "San Joaquin, Bolivia"), — Ellis, 1913: 139-140, pi. 23, fig. 2 (nearly a repetition of original description; holotype figured).

Specimens examined: BOLIVIA. — FMNH 54554 (ex-CM 3182), 1 specimen (holotype), 211 mm tl (tip of caudal filament regenerated), Est. Béni, Rio Guaporé system, Rio Machupo at San Joaquin, coll. J. D. Haseman, 5-IX-1909. Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013

COLOMBIA. — CAS (SU 50679), 1 specimen, 144 mm si (tip of caudal filament broken), Caqueta Prov., small brook across Rio Orteguaza from ,Tres Esquinas (00°45' N, 75° 15' W), coll. T. D. White, J. N. Reynolds, L. Wulff & G. S. Myers, 13-11-1958; — ANSP 128496,1 specimen, ZMA 112.988, 1 specimen, 252-256 mm tl, Meta Prov., Quebrada Venturosa, 1/4 creek 42 H. NÜSSEN et al.

Table 1: Morphometric data of five specimens of Gymnorhamphichthys hypostomus (samples 01 through 03) and of 200 specimens of G. rondoni (samples 04 through 37). Sample 0I=FMNH 54554 (holotype of G. hypostomus; the specimen of sample 02 is shown in fig. 3; sample 11=MNRJ 3631 (holotype of G. rondoni); sample 19=GSC 340.1 (holotype of G. h. petiti); sample 31 = BMNH 1972. 12.4.24 (one), MCZ 46888 (one), CAS (IUM 12613) (two), and BMNH 1972.12.4.2-15 (one); sample 32=CAS (IUM 12641) (two), and USNM 190551 (one); sample 33=MCZ 48557 (one), MCZ 48558 (one), and MCZ 46888 (three). The specimen of sample 35 is shown in fig. 12.

sample country locality N tl (mm) si (mm) sl/hl 01 Bolivia Rio Machupo 1 broken 182 4.6 02 Colombia Rio Orteguaza 1 broken 144 5.9 03 Colombia Quebrada Venturosa, Rio Metica 3 (N = 2) —256 167-187 5.8-6.5 04 Brazil Rio Cueiras 2 97-204 67-143 5.4-5.5 05 Brazil Barro Branco Creek 9 (N = 7) 222-269 145-173 5.0-5.4 06 Brazil Rio Sanabani 1 broken 153 4.6 07 Brazil Rio Prêta da Eva 1 195 139 5.6 08 Brazil Japu Creek 3 206-227 156-168 4.6-5.1 09 Brazil Rio Uaupés 2 103-119 72- 83 6.3-7.0 10 Brazil Sao Salvador Creek 1 187 133 5.5 11 Brazil Rio 17 de Fevereio I 118 85 6.9 12 Brazil Rio Cururu 3 (N = 2) 150-160 107-114 5.1-5.3 13 Brazil Rio Cururu 1 broken 81 6.4 14 Brazil Rio 7 de Setembre 1 broken 79 7.7 15 Brazil Suiâ Missu Creek I broken 56 5.9 16 Brazil Yamarikumâo Lake 2 96-117 64- 81 5.9-6.1 17 Brazil 5 km from Posto Diaurum 2 119-160 82-109 4.8-5.4 18 Brazil Base camp stream 3 101-143 68- 98 5.9-6.2 19 Brazil Ilha do Bananal 1 121 86 6.5 20 Surinam Gran Rio 23 124-168 95-118 5.3-6.0 21 Surinam Parwapa Creek 25 (N = 23) 160-214 (N=23) 121-154 (N = 23) 4.9-5.6 22 Surinam Jenjee Creek 13 {N= 11) 171-196 124-141 5.1-5.6 23 Surinam Marowijne Creek 7 132-168 98-123 5.7-6.3 24 Surinam Makambi Creek 1 87 64 5.9 25 Surinam Compagnie Creek 1 197 145 5.3 26 Surinam Coppename River 20 128-181 94-128 5.0-5.8 27 Surinam Coppename River 3 128-170 109-126 5.3-6.1 28 Surinam Nickerie River 25 (N = 24) 127-181 91-136 5.3-6.1 29 Surinam Avanavero Falls 6 (N = 5) 181-206 (N=5) 130-142 (N=5) 5.3-5.8 30 Surinam Sipaliwini River 1 176 139 5.5 31 Guyana - explanation in legend - 5 63-131 46- 97 5.6-6.9 32 Guyana - explanation in legend - 3 (N = 2) 141-148 98-115 5.8-6.1 33 Guyana - explanation in legend - 5 159-178 117-128 5.0-5.5 34 Venezuela upper Rio Orinoco 6 (N = 5) 123-191 81-129 6.2-6.7 35 Colombia Rio Orteguaza 1 broken 147 5.3 36 Colombia Rio Orteguaza 18 (n=16) 73-155 55-122 5.8-6.7 37 Colombia Rancho El Viento 3 113-136 75- 91 5.6-6.2 Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 GYMNORHAMPHICHTHYS SPECIES FROM SOUTH AMERICA 43

sl/sn si/ pal sl/an hl/sn hi/an tl/la 7.3 4.6 6.8 1.6 1.5 — 10.1 5.9 6.1 1.7 1.0 —

9.8-11.2 5.9-6.5 7.4-12.2 1.7 1.1-2.1 (N = 2) .63-1.64 9.1-11.0 5.2-8.9 5.8-6.1 1.7-2.0 1.1 .63-1.74 8.3- 9.2 4.9-5.3 (N=l) 6.4 1.6-1.7 (N=l) 1.3 (N = 7) .84-1.93 7.3 4.5 8.6 1.6 1.9 9.6 5.8 10.2 1.7 1.8 .70 7.4- 8.8 4.7-5.2 10.8-12.4 1.6-1.7 2.3-2.5 .68-1.71 14.0-16.7 6.3-6.8 7.2- 7.5 2.1-2.3 1.0-1.1 .63-1.71 10.2 5.3 10.7 1.8 2.1 .73 13.7 6.3 7.0 2.0 1.0 .65 9.5- 9.9 5.3-5.5 5.6- 8.7 1.9 1.1-1.7 (N = 2) .72-1.73 13.1 6.3 7.1 2.0 1.1 18.2 7.9 9.2 2.4 1.2 — 13.3 5.6 6.1 2.3 1.0 — 11.6-13.6 5.9-6.1 6.8- 6.9 2.0-2.2 1.1 1.73-1.80 8.7-10.5 4.8-5.7 8.1- 9.1 1.8-2.0 1.5-1.9 1.76-1.86 11.0-12.4 5.7-6.2 6.5- 7.4 1.9-2.0 1.0-1.2 1.74-1.80 13.7 6.9 5.9 2.1 0.9 1.65 9.3-11.2 5.5-6.3 5.0-11.9 1.7-1.9 1.1-2.1 (N=l 1)1.56-1.75 (N=23) 7.9-10.0 (N = 23) 5.0-6.2 (N = 23) 8.8-12.5 1.6-1.9 1.6-2.3 (N = 23) 1.59-1.82 8.7- 9.9 5.5-6.1 9.8-12.0 1.6-1.8 1.9-2.2 (N=l 1)1.55-1.77 10.3-11.8 5.8-6.5 6.4- 7.2 1.8-1.9 I.1-1.2 1.59-1.73 12.3 5.8 6.3 2.1 1.1 1.64 9.1 5.5 10.6 1.7 2.0 1.66 8.4-10.6 5.2-6.0 8.3-12.6 1.7-1.8 1.7-2.3 1.54-1.83 9.2-11.2 5.4-6.1 12.4-14.5 1.7-1.9 2.3-2.4 1.41-1.65 9.5-11.2 5.5-6.3 6.5-12.7 1.8-2.0 1.2-2.2 (N = 24) 1.53-1.74 (N = 5) 9.6-11.0 (N = 5) 5.2-5.5 (N = 5) 10.1-12.1 1.8-2.0 1.8-2.2 (N=3) 1.69-1.80 9.9 5.5 9.9 1.8 • 1.8 1.55 10.4-17.0 5.5-6.5 5.9- 7.1 1.9-2.5 1.0-1.1 1.65-1.76 11.2-12.1 5.6-5.7 11.4-12.9 1.9-2.0 2.0-2.1 (N=2) 1.74-1.75 8.8-10.4 5.2-5.4 9.4-11.9 1.7-1.9 1.8-2.2 . 1.64-1.72 10.7-14.2 6.4-7.2 6.6- 8.8 1.7-2.1 1.0-1.4 (N = 5) 1.53-1.8 8.3 5.3 10.0 1.6 1.9 — 10.7-12.8 (N= 17) 5.7-6.7 (N=I7) 5.7-6.9 1.8-2.0 (N = 17) 1.0-1.1 (N= 15) 1.46-1.69 9.1-11.3 5.7-6.4 6.2- 6.7 1.5-1.9 1.0-1.2 1.72-1.82 Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 44 H. NÜSSEN et al.

Fig. 2. Gymnorhamphichthys hypostomus from Colombia, Quebrada Venturosa (ZMA 112.988), tl 252 mm, showing midlateral blotches (snout bend during preservation). Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013

Fig. 3. Gymnorhamphichthys hypostomus from Colombia, Rio Orteguaza (CAS (SU 50679)), si 144 mm, showing differences in shape of head, size of eye, and colour pattern (compare with sympatric specimen of Gymnorhamphichthys rondoni shown in fig. 12). GYMNORHAMPHICHTHYS SPECIES FROM SOUTH AMERICA 45

Fig. 4. Colour pattern in a) Gymnorhamphichthys hypostomus, holotype, tl >212 mm, — and in four specimens of Gymnorhamphichthys rondoni: b) Brazil, Rio Cuieras, tl 204 mm, c) Brazil, Sao Salvador Creek, tl 187 mm, d and e) Surinam, Jenjee Creek, tl 178 and 187, respectively.

mile above road between La Balsa and Puerto Lopez (approximately 04° 05' N, Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 72°58' W), coll. J. E. Böhlke, W. G. Saul & W. Smith-Vaniz, 15-III-1973; — ANSP 124254, 1 specimen, 167 mm si (tip of caudal filament broken), Meta Prov., Rio Metica, about 1.5 km east of Rajote (03°56' N, 73°03' W), coll, J. E. Böhlke, W. G. Saul & W. Smith-Vaniz, 19-111-1973; — ANSP 124255, 1 specimen, 139 mm long (damaged), Meta Prov., Cano Emma, Hacienda 'El Viento', 32 km ENE of Puerto Lopez (04° 09' N, 72° 39' W), coll. J. W. Richardson jr, 15-11-1973. 46 H. NIJSSEN et al.

Description. — Actual measurements of the holotype: tl 211 mm (tip of caudal filament regenerated), si 182 mm, hi 39.2 mm, sn 24.8 mm, pal 39.5 mm, an 26.9 mm, eye 1.3 mm. A formal redescription is omitted here. A discussion of certain characters and differences with Gymnorhamphichthys rondoni is given in the section on G. rondoni.

Gymnorhamphichthys rondoni (A. de Miranda Ribeiro, 1920) (figs. 4b-e, 5-16, tables 1-2) Gymnorhamphichthys hypostomus; Ellis, in Eigenmann, 1912: 436-437 (origi- nal description; in part; paratype localities: "Rio Mamoré", "Konawaruk", "Bastos", "Maciel, Rio Guaporé", "Puerto Bertoni, Alto Parana", "Tumatumari"), — Ellis, 1913: 139-140, pi. 15 (nearly identical repetition of original description), — Knöppel, 1970: 335 (2 pyloric app.), page 337 (insect larvae), page 348 (listed). U[rumara\ rondoni Alipio de Miranda Ribeiro, 1920: 6-7 (original description; type locality: Brazil, "... rio Dezesete de Fevereio, affluente da margem esquerda do Alto Cautario, valle do Amazonas"). Urumaria rondoni; Fowler, 1951: 419 (in footnote; misspelling). Urumara rondoni; Curra & Paulo de Miranda Ribeiro, 1961: 474-482, figs. 1-2, 1 table, 1 page errata (redescription of the holotype; comparison with Gymnorhamphichthys and Rhamphichthys). Urumara rondoni; Géry & Vu, 1964: 485, 492 (discussion). Gymnorhamphichthys hypostomus petiti Géry & Vu, 1964: 486-492, figs. 1-3, pi. 1, table 1 (original description; type locality: Brazil: "Ilha do Bananal, haut Rio Araguaia,..."). Gymnorhamphichthys hypostomus ssp. Géry & Vu, 1964: 490, table 1 (mor- phometric and meristic data of a specimen from Surinam, Makambi Creek, RMNH 18407). Gymnorhamphichthys hypostomus "cf. ssp. nov." Knöppel, 1970: 297 (Ig. Barro Branco; stomach contents). Gymnorhamphichthys sp. Knöppel, 1970: 329, table 45 (same specimens as recorded on page 297). Specimens examined: PARAGUAY. — CAS (IUM 12642), 1 specimen (paratype of Gymnorhamph- Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 ichthys hypostomus), 125 mm tl, Est. Alto Parana, Rio Parana at Puerto Bertoni, coll. A. de W. Bertoni, 1910.

BRAZIL. — GSC, 2 specimens, 97-204 mm tl, Est. Amazonas, Rio Negro sys- tem, Rio Cueiras, a few hours by boat above Manaus, coll. E. J. Fittkau, 1965; — MPIL 1291/1299, 9 specimens, 219 (tip of caudal filament broken)- 269 mm tl, Est. Amazonas, Barro Branco Creek in the "Réserva Ducke" above GYMNORHAMPHICHTHYS SPECIES FROM SOUTH AMERICA 47

Manaus, coll. E. J. Fittkau, XI-1965 (specimens MPIL 1296 and 1297 deposited at GSC); — MZUSP 7444, 1 specimen, 201 mm tl (tip of caudal filament broken), Est. Amazonas, Rio Sanabani at Silves (02° 48' S, 58° 08' W), coll. Amazonia Expedition 7/8-XII-1967; — IRScNB 16431, 1 specimen, 195 mm tl, Est. Amazonas, Rio Prêta da Eva, upper course, coll. G. Marlier, 28-11-1964; — IRScNB 17783, 3 specimens, 206-227 mm tl, Est. Amazonas, Rio Uaupés system, Japu Creek at left bank of Rio Tiquié, coll. J. P. Gosse, 7-XII-1967; — IRScNB 17784, 2 specimens, 103-119 mm tl, Est. Amazonas, tributary at right bank of Rio Uaupés at Trovao, 20 km upstream of mouth of Rio Uaupés, coll. J. P. Gosse, 9-XII-1967; — IRScNB 17785, 1 specimen, 187 mm tl, Est. Acre, Sao Salvador Creek at left bank of Rio Mao near Cruzeio do Sul, coll. J. P. Gosse, 30-XI-1967; — MNRJ 3631, 1 specimen (holotype of Urumara rondonî), 118 mm tl (bad condition), Est. Rondonia, Rio Guaporé system, Rio 17 de Fevereio at left bank of upper Rio Cautario, coll. C. M. da S. Rondon, no date; — FMNH 54555, 1 specimen (paratype of Gymnorhamphichthys hypostomus), 160 mm tl, Est. Rondonia, Rio Mamoré, below mouth of Rio Guaporé, coll. J. D. Haseman, 19-IX-1909; — MCZ 9398, 2 specimens, 98-132 mm si (tip of caudal filaments broken; bad condition), Est. Para, Rio Tapajôs, coll. Dexter, Talisman & James, Thayer Expedition, 1865; — IRScNB 17786, 3 specimens, 130-160 mm tl (tip of caudal filament broken in one specimen), Est. Para, Rio Cururu, tributary at left bank of upper Rio Tapajös, coll. J. P. Gosse, 20-XI-1964; — IRScNB 17787, 1 specimen, 113 mm tl (tip of caudal filament broken), same locality as IRScNB 17786, coll. J. P. Gosse, 19-XI-1964; — FMNH 54556 (ex-CM 3184 a-b), 2 specimens (paratypes of Gymnorhamphichthys hypostomus), 73-108 mm tl, Est. Mato Grosso, Rio Alegre at Bastos, 8 miles S of Villa de Mato Grosso, Rio Guaporé system, coll. J. D. Haseman, 26/28-VI-1909; — FMNH* 54557 (ex-CM 3185a), 1 specimen (paratype of Gymnorhamphichthys hypostomus), 78 mm tl, Rio Guaporé at Maciel, coll. J. D. Haseman, 1909; — GSC, 1 specimen, 79 mm si (tip of tail broken), Est. Mato Grosso, Rio 7 de Setembre, tributary of upper Rio Xingü, coll. E. J. Fittkau, VII-1965; — IRScNB 17788, 1 specimen, 56 mm si (tip of tail broken), Est. Mato Grosso, Suiâ Missu Creek at Posto Diauarum, tributary of upper Rio Xingû, coll. J. P. Gosse, 24-X-1964; — IRScNB 17789, 2 specimens, 96-117 mm tl, Est. Mato Grosso, creek from Yamarikumäo Lake at Suiâ Village, upper Rio Xingü, coll. J. P. Gosse, 3-IX-1964; — IRScNB 17790, 2 specimens, 119-160 mm tl, Est. Mato Grosso, forest creek, 5 km from Posto Diauarum, upper Rio Xingü, coll. J. P. Gosse, 12-XI-1964; — BMNH 1972.12.4.25-27, 3 specimens, 101-143 mm tl, Est. Mato Grosso, base camp stream, Xaventina- Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 Cachimbo expedition, coll. R. H. Lowe-McConnell, 28-1V-1968; — GSC 340, 22 specimens (holotype and paratypes of Gymnorhamphichthys hypostomus petitî), 73-122 mm tl, Est. Goiâs, Ilha do Bananal, upper Rio Araguaia, coll. H. Schultz, VII-1959 (1 specimen deposited in Zoologische Sammlung des Bayerischen Staates, not re-examined). 48 H. NÜSSEN et al.

Fig. 5. Gymnorhamphichthys rondoni, holotype, showing the condition of the specimen (MNRJ 3631) nowadays.

SURINAM. — ZMA 106.023, 6 specimens, 143-162 mm tl, Suriname River system, creek at right bank of Gran Rio, 2.5 km NE of Awa (=Awara) Falls, depth 20-100 cm, width 2 m, running water, bottom sand, fish poison, coll. H. Nijssen, 28-1-1967; — ZMA 106. 923, 1 specimen, 149 mm tl, Suriname River system, Gran Mau Creek at right bank of Gran Rio, 1 km N.E. of Dombaai (=Bendi Watra) Village, depth 50-100 cm, width 5 m, bottom sand and mud, fish poison, coll. H. Nijssen, 30-1-1967; — ZMA 106.027, 14 specimens, 124-168 mm tl, Suriname River system, creek at right bank of Gran Rio, 4 km N.E. of Awa Fall, depth 30-150 cm, width 6 m, running water, bottom sand, fish poison, coll. H. Nijssen, 31-1-1967 (2 specimens deposited in Universidad del Salvador, San Miguel, Argentina); — ZMA 106.021, 5 speci- mens, 144-160 mm tl, Suriname River system, creek at left bank of Gran Rio, 3 km N.E. of Awa Fall, depth 20-100 cm, width 2 m, running water, bottom sand and mud, fish poison, coll. H. Nijssen, l-H-1967; — ZMA 106.029, 23 specimens, and ZMA • 106.055, 2 specimens, 160-214 mm tl, Suriname River system, Parwapa (=Paba) Creek at left bank of Suriname River, 2.5 km N. of Botopasi Village at Foetoenakaba (=Voettoekaba) Village, depth 50-100 cm, width 8 m, running water, bottom sand, fish poison, coll. H. Nijssen, 20-111-1967; — ZMA 106.022, 13 specimens, 171-196 mm tl, Suriname River system, Jenjee Creek at right bank of Suriname River, 7.5 km N. of Botopasi Village, depth 30-120 cm, widt 3 m, running water, bottom sand, fish poison, coll. H. Nijssen, 21-111-1967; — ZMA 106.020, 7 specimens, 132-168 mm tl, Suriname River system, Marowijne (=Gran) Creek, 63 km S. of dam at Afobaka, depth 150 cm, running water, bottom Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 sand and decaying leaves, fish poison, coll. H. Nijssen, 20-X-1966; — RMNH 18407,1 specimen, 87 mm tl, Suriname River system, Makambi Creek, coll. D. C. Geijskes, 27 - IX-1938; — RMNH 26677, 1 specimen, 197 mm tl, Suriname River system, Compagnie Creek, coll. G. F. Mees, 15-III-1966; — ZMA 106.028, 20 specimens, 128-181 mm tl, Coppename River system, creek at left bank of Coppename River on northern slope of Wilhelmina Mountains (03°52' N, 56°55' W), depth 30-100 cm, width 4 m, running water, bottom GYMNORHAMPHICHTHYS SPECIES FROM SOUTH AMERICA 49

sand and mud, fish poison, coll. H. Nijssen, 18-V-1967; — ZMA 106.019, 3 specimens, 128-170 mm tl, Coppename River system, creek at right bank of Coppename River on northern slope of Wilhelmina Mountains (03°52'30" N, 56° 53' W), depth 50-200 cm, width 3-5 m, running water, bottom sand and mud, fish poison, coll. H. Nijssen, 19-V-1967; — ZMA 106.030, 54 specimens, 127-179 mm tl, Nickerie River system, creek at right bank of Nickerie River, 12 km W.S.W. of Stondansie Falls, depth 50-100 cm, width 7 m, running water, bottom sand, fish poison, coll. H. Nijssen, 5-IV-1967; — ZMA 106.026, 2 specimens, 150-156 mm tl, Nickerie River system, Stondansie Falls in Nickerie River, width 80 cm, bottom sand and rocks, fish poison, coll. H. Nijssen, 5-IV-1967- — RMNH 26678, 6 specimens, 181-206 mm tl, Corantijn River system, Avanavero Falls in Kabalebo River, coll. G. F. Mees, 24-IX-1965: — RMNH 26679, 1 specimen, 176 mm tl, Corantijn River system, Sipaliwini River near airstrip Sipaliwini, coll. G. F. Mees, 23-I-1966.

Fig. 6. Comparison of the head shape of the holotype of Gymnorhamphichthys hypostomus (upper figures), and the holotype of Gymnorhamphichthys rondoni (lower figures), showing different angles of the snout with the axis — a) taken from Curra & P. de Miranda Ribeiro (1961, figs. 2b and c), b) our interpretation of the same figures.

GUYANA. — CAS (IUM 12641), 2 specimens (paratypes of G. hypostomus), 141-148 mm tl, Essequibo River at Konawaruk, coll. C. H. Eigenmann, 1908; — CAS (IUM 12613), 2 specimens (paratypes of G. hypostomus), 95-98 mm tl, lower Potaro River at Tumatumari, coll. C. H. Eigenmann, 1908; — Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 BMNH 1972.12.4.24,1 specimen, 128 mmtl, Sandcreek Rockpool, tributary of Rupununi River, coll. R. H. Lowe-McConnell, 30-IV-1961; — BMNH 1972.12.4.2-15, 14 specimens, 62-88 mm tl, Rupununi River, sandbank at- Karanambo, coll. R. H. Lowe-McConnell, 25-IX-1957; — BMNH 1972.12.4. 16-20, 5 specimens, 58-96 mm tl, Rupununi River at Karanambo, in sand, coll. R. H. Lowe-McConnell, 27-XM958; — USNM 190551,1 specimen, 115 mm si (tip of tail broken), Rupununi River at Dadanawa, no date; — MCZ 48557, 50 H. NÜSSEN et al.

1 specimen, 171 mm tl, Crusa Creek, tributary of Rupununi River at Moco- Moco settlement, coll. C. Hopkins, Roth & Cichocki, 3-V-1971; — MCZ 48558, 1 specimen, 163 mm tl, Kumaka Swamp, Moco-Moco Creek, tributary of Rupununi River, seine,, coll. C. Hopkins, 13-V-197I; — MCZ 46888, 4 specimens, 131-178 mm tl, Moco-Moco Creek, tributary of Rupununi River, coll. C. Hopkins, 15-IX-1969; — BMNH 1972.12.4.21-23, 3 specimens, 112-125 mm tl, Rupununi District, coll. R. H. Lowe-McConnell, l-XII-1958; — BMNH 1972.7.27.531, 1 specimen, 120 mm tl, Mazaruni River, coll. M. Alleridge, no date; — BMNH 1972.7.27.902, 1 specimen (broken), Rupununi River, sandcreek pools, coll. R. H. Lowe-McConnell, IV-1961.

•s. 11 .5.0

a u.o

13.0 S 1 • • a .„ . . A 12.0

* 00 0 0 • •••s •", 11.0 g . \

0» « •• • V . •

10.0 S

• * 8o# X * 9.0

• 0 8.0 * 0 •

X 0 7.0 • * •V ": K 6.0 X 0 X

S.O 0

(0 SO 60 70 80 90 100 110 120 130 liO 150 160 170 180 190 il in mm

Fig. 7. Relation of ratio standard length/pre-anal papil length in standard length in 5 specimens of Gymnorhamphichthys hypostomus (represented by triangles), and in 188 specimens of Gymnorhamphichthys rondoni (specimens from Surinam and Guyana are represented by open circles, specimens from other localities by crosses. Black dots represents a circle and a cross at the same spot). Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 VENEZUELA. — IRScNB 15236, 16 specimens (bad state), 103-191 mm tl, upper Rio Orinoco, between San Fernando de Atabapo and Casiquiare Canal, coll. de Wavrin, 1935.

COLOMBIA. — CAS (SU 67918), 48 specimens, 55-147 mm si (several tips of caudal filaments broken), Caqueta Prov., small brook across Rio Orte- GYMNORHAMPHICHTHYS SPECIES FROM SOUTH AMERICA 51

guaza from Très Esquinas (00°45' N, 75° 15' W), coll. T. D. White, J. N. Reynolds, L. Wulff & G. S. Myers, 13-11-1958; — CAS (SU 50491), 2 specimens, 83-133 mm tl, same locality as CAS (SU 67918), coll. T. D. White & G. S. Myers, 7-II-1958; — ANSP 121626, 3 specimens, 113-136 mm tl, Meta Prov., Rancho El Viento (second stream after entering ranch, stream past ranch house), across Rio Meta, about 4 km from Puerto Lopez, depth to 30 cm, coll. J. E. Böhlke, N. Foster & J. Thomerson, 28-111-1971.

-i '

90

85

80

7.5

X 7.0 0 0 M 65 x XDI XX X • OK MO X 0 0 XO 0 60 0 «0 O 0 X A 0 X 01 0 X« O X '4 X 0 0 00 00 000 0 0 0 00 000 0 00 X OOOOOOO» 0 0 «X 5.5 o ooo» ooao s oo oo en 0 0 X 0 00 0 OOO 00 X X 0 0 0« 5.0 0 0 0 0 0 0 X 0 0

X X iS • A

to 40 50 60 70 60 90 100 120 130 KO 150 160 170 110 190 si in mm

Fig. 8. Relation of ratio standard length/head length in standard length in 5 specimens of Gymnorhamphichthys hypostomus and in 191 specimens of Gymnorhamphichthys ron- doni, showing relatively longer heads in large specimens, due to the differential growth of the snout. Symbols as in fig. 7.

Description. — Morphometric data of 200 specimens and anal fin ray counts of 74 specimens are compiled in tables 1 and 2. Shape and colour pattern of Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 some representative specimens are shown in figures 4, 12, 13, and 14. Figure 15 shows some osteological features. The relations of the ratio of standard length/pre-anal papil length in standard length, of the ratio standard length/ head length in standard length, of the ratio standard length/ snout length in standard length, and of the ratio total length/anal fin length in total length, are given in scatter diagrams, figures 7, 8, 9, and 10, respectively. In these diagrams, specimens from Surinam and Guyana are represented by open 52 H. NÜSSEN et al.

circles, specimens from other localities by crosses; in these figures a black triangle represents the holotype of Gymnorhamphichthys hypostomus, and open triangles represent the other specimens of G. hypostomus. Black dots represent a circle and a cross at the same spot. The localities are indicated in figures 11 and 16. In 34 samples of 1 to 25 individuals, the total length varies from 63 to 269 mm, the standard length from 46 to 173 mm. The head length is contained 4.6-7.7 in standard length, the snout 7.3-17.0 in standard length (1.5-2.5 in head length), the distance from snout to anal fin 4.5-8.9 in standard length, and the distance from snout to anus (anal pore or anal papilla) 5.0-14.5 in standard length (0.9-2.5 in head length). The length of the anal fin varies from 1.41-1.93 in total length, and the number of anal fin rays varies from 136-173. Some of the data indicate that the material examined could eventually prove to be hetero- geneous. It is clear from the counts of the anal fin rays of 74 specimens of this species and of 5 specimens of Gymnorhamphichthys hypostomus, that the latter have the number of anal fin rays well above the mean for G. rondoni (see table 2).

Table 2: Anal fin counts in five specimens of Gymnorhamphichthys hypostomus (above dotted line), and of 74 specimens of G. rondoni.

locality N si (mm) A Rio Machupo (holotype) 1 182 181 Rio Orteguaza 1 144 196 Quebrada Venturosa, Rio Metica 3 167-187 199-207 Barro Branco Creek 4 145-171 145-153 Japu Creek 2 156-162 144-149 Rio Uaupés 2 103-119 153-163 Sao Salvador Creek 1 133 158 Rio Cururu 3 107-114 154-173 Suiâ Missu Creek 1 56 136 Yamarikumao Lake 2 64- 81 143-148 5 km from Posto Diaurum 2 82-109 139-143 Jénjee Creek 1 133 162

Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 Marowijne Creek 7 98-123 143-169 Makambi Creek 1 87 157 Compagnie Creek 1 145 166 Nickerie River 10 105-136 157-172 Tumatumari 2 67- 68 171 Konawaruk 2 98-103 155-158 Crusa Creek, Kumaka Swamp, and Moco-Moco Creek 4 118-126 155-172 Rio Orteguaza 1 147 154 Rio Orteguaza 28 57-123 144-167 GYMNORHAMPHICHTHYS SPECIES FROM SOUTH AMERICA 53

POSITION OF THE ANAL PORE

(1) The anal papilla. The measurement an indicates either the position of the anal opening or the tip of the anal papilla. Several juvenile specimens and some larger specimens do not possess an anal papilla at all (figs. 13d and g). Others bear an indication of a minute anal papilla (fig. 13e), whereas there are also specimens with a distinct anal papilla pointing downwards (fig. 13a). The measurement an is taken in all these cases to the centre of the anal pore. Many specimens, how- ever, have developed an anal papilla which protrudes far forward, often covering the anal opening entirely (figs. 13b, c and f)- In these cases it was often found difficult to locate the anal opening without damaging the anal papilla and the area around it, as it is enclosed tightly between folds of skin in the midline between the branchiostegal membrane. Therefore, the measurement an is taken to the tip of the anal papilla in such cases. In fig. 13 the position of the anal opening is indicated by an arrow.

17.0

16.0

15.0

11.0

13.0

12.0

11.0

10.0 • :• .„ .v v . 9.0 O «O ." OlIflORO

8.0

<0 50 60 70 80 90 100 110 120 130 U0 150 160 170 180 190 ft in mm Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 Fig. 9. Relation of ratio standard length/ snout length in standard length in 5 specimens of Gymnorhamphichthys hypostomus and in 192 specimens of Gymnorhamphichthys ron- doni, showing relatively longer snouts in large specimens. Symbols as in fig. 7. (2) The position of the anal pore. The position of the anal pore may change during growth as the results of measurements of the distance between the snout tip and the anal pore (or papilla) 54 H. NÜSSEN et al.

indicate. In the one extreme it is situated far anterior to a vertical extending from the eye; in the other it is situated on a vertical extending from the pectoral fin base. The range of the anal pore position, measured from snout tip and expressed as proportions of head length (hi/an) or standard length (si/an), is shown in figures 7 and 13 and in table 1 (0.9-2.5 in head length). At this stage no explanation can be given for this observed variability in pore position, but the following possibilities have been considered: 1) That the most posterior position is a juvenile character. Of the specimens with a standard length less than 100 mm, about 86% have hi/an <1.2 or si/an <7.5. However, it has also been found in sexually mature individuals. 2) That it is a sexually dimorphic character. Again, there is no evidence for this as the entire range of variation is found in both sexes. 3) That it can be correlated with geographical distribution. But an examination of the 70 specimens collected in the Suriname river system showed the following: In 44 specimens the anal pore is situated anteriorly to the eye, 9 specimens have the anal pore situated just below the eye, whereas in 17 specimens it is situated posteriorly to the eye. Of 54 specimens from the Nickerie river system, 8 have the anal pore situated anteriorly to the eye, 5 below the eye, and 41 posteriorly to the eye, which is a reverse situation to that found in the Suriname river system. Expressed as proportions of the head length, 25 spe- cimens from Nickerie River (ZMA 106.030), 91-136 mm standard length, have the following distance between snout tip and origin of the anal pore (number of specimens in parentheses): 1.2 (7), 1.3 (3), 1.4 (2), 1.5 (1), 1.6 (1), 1.7 (3), 1.8 (1), 1.9 (2), 2.0 (1), 2.1 (3), 2.2 (1). Such a considerable variability is also found in large series from other localities. It is expressed in standard length and plotted for all examined material in fig. 7. Seven specimens from Marowijne Creek (ZMA 106.020), 98-123 mm standard length, are much less variable, alUiaving the anal pore close to a vertical extending from the pectoral fin base: six specimens have 1.1 and one has 1.2 expressed as a proportion of the head length. All twenty-three specimens from Coppename River (ZMA 106.028), 94-126 mm standard length have the anal pore anterior to the eye: 1.7(1), 1.9 (4), 2.0 (8), 2.1 (2), 2.2 (3), 2.3 (2), and 2.4 (2). The variability in the position of the anal pore makes this unsuitable for use as a taxonomic character. Physiological and perhaps ecological studies may indicate the reason for this variability.

Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 SHAPE OF THE HEAD AND LENGTH OF THE SNOUT We have found in our material the same positive allometry for the snout that was found by Ellis in her material, and by Géry & Vu in 22 specimens from Ilha do Bananal. This is expressed in fig. 9. The snout length in juveniles up to 90 mm si may vary considerably, as shown in fig. 9 (from 9.1 to 18.2 in standard length). Specimens longer than GYMNORHAMPHICHTHYS SPECIES FROM SOUTH AMERICA 55

90 mm si always have a snout ratm of less than 13.0 in standard length. Specimens longer than 150 mm si have a snout length of 7.3 to 8.9 in standard length.

"uo

its

t.eo

1.7S X • 0 0» #

1.70

0 O X O 0« 0 0 00 0 « O 00 00 0 O 1.65 0 I 00

1.10

1.55

1.50

1.45

1.(0

80 100 120 UO 160 180 200 220 2&Q 260 200 tl in mm Fig. 10. Relation of ratio total length/anal fin length in total length in 2 specimens of Gymnorhamphichthys hypostomus and in 173 specimens of Gymnorhamphichthys ron- doni, showing variability in anal fin length, without correlation. Symbols as in fig. 7.

Curra & P. de Miranda Ribeiro (1961), discussing the validity of the genus Urumara, compared the head of the holotype of Urumara rondoni with the head of the holotype of Gymnorhamphichthys hypostomus. The differences in the angle of the snout with the axis mentioned by Curra & P. de Miranda Ribeiro for Gymnorhamphichthys hypostomus (6°) and Urumara rondoni (12°) are due to the fact that the latter species is represented by a single juvenile specimen, which was compared with the figure of the adult holotype of the former species. Géry & Vu (1964) measured a variation in the angle of the

Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 snout with the axis from 0° to 12° in their 22 specimens. Moreover, figure 2 of Curra & P. de Miranda Ribeiro (our fig. 6a), showing the supposed difference between Gymnorhamphichthys and Urumara, is somewhat mis- leading and poorly executed cf. fig. 6b which shows the differences of the shape of the head in an adult specimen (above), and in a juvenile specimen (below), commonly found in Gymnorhamphichthys rondoni (unfortunately, no juvenile specimens of Gymnorhamphichthys hypostomus are known to us). The snout of the holotype of Urumara rondoni is in bad shape, as shown in fig. 5. 56 H. NÜSSEN et al.

Fig. 13'shows the variability found in the shape of the head and in the length of the snout. Fig. 13f shows an adult specimen 221 mm total length, and fig. 13g a juvenile specimen of about 70 mm total length (tip of caudal filament broken). Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013

Fig. 11. MapofSouth America showing localities where Gymnorhamphichthys hypostomus (star means holotype, cross means non-type) and Gymnorhamphichthys rondoni (square means holotype, triangle means holotype of Gymnorhamphichthys hypostomus petiti, dot means non-type) were collected. GYMNORHAMPHICHTHYS SPECIES FROM SOUTH AMERICA 57

NUMBER OF ANAL FIN RAYS Ellis (1913: 139) records 165 to 210 anal fin rays in Gymnorhamphichthys hypostomus without reference to particular specimens. However, we were unable to find a specimen that possessed 210 fin rays. Of the nine available specimens of Ellis' type material we re-examined, the holotype possesses the highest number of anal fin rays (181). Curra & P. de Miranda Ribeiro (1961: 476) record "154 (?)" anal fin rays in the holotype of Urumara rondoni. Géry & Vu (1964: 488) mention 147 to 170 anal fin rays for their subspecies Gymnorhamphichthys hypostomus petiti, and 161 for a specimen from Surinam (RMNH 18407, Makambi Creek). The number of anal fin rays in the type material of Gymnorhamphichthys hypostomus petiti falls within the range of the variation found in several populations: 136 to 173. The five specimens of Gymnorhamphichthys hypostomus having the anal fin undamaged show a range of 181 to 207 anal fin rays (see table 2). Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013

Fig. 12. Gymnorhamphichthys rondoni from Colombia, Rio Orteguaza (CAS (SU 67918), si 147 mm (compare with sympatric specimen of Gymnorhamphichthys hypostomus shown in fig. 3). 58 H. NÜSSEN et al. Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 10mm Fig. 13. Gymnorhamphkhthys rondoni. Outlines showing variability in shape of head, snout length, and position of the anal pore: a, b, and c) Surinam, Nickerie River (ZMA 106.030), male 149 mm tl, female 161 mm tl and a specimen 153 mm tl (broken), respectively, d and e) Surinam, Marowijne Creek (ZMA 106.020), specimens of 147 and 167 mm tl, respecti- vely, 0 Brazil, Japu Creek (IRScNB 17783), a specimen 221 mm tl, g) Brazil, Suiâ Missu Creek (IRScNB 17788), a specimen 70 mm tl (broken). GYMNORHAMPHICHTHYS SPECIES FROM SOUTH AMERICA 59

NUMBER OF VERTEBRAE Radiographs were made from 10 specimens from Surinam, Nickerie River (ZMA 106.030). Six have 12 and four have 11 abdominal vertebrae. The following numbers of caudal vertebrae were counted (number of specimens in parentheses): 61 (1), 69 (1), 81 (1), 84 (1), 85 (1), 86 (1), 87 (2), 91 (1), the tenth specimen was mutilated and had 57 caudal vertebrae only. This variation in numbers of the caudal vertebrae can be accounted for by the fact that some specimens have been injured and the vertebrae have regenerated as a single partly ossified column.

Fig. 14. Gymnorhamphichthys rondoni from Jenjee Creek, Suriname River system, 133 mm si (ZMA 106.022). Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013

Fig. 15. Radiograph of Gymnorhamphichthys rondoni from Nickerie River, Surinam (ZMA 106.030), 120 mm si. 60 H. NÜSSEN et al.

COLOUR In life, Gymnorhamphichthys rondoni is translucent except for the head and body cavity. Vertebrae and fin rays are as clearly visible as shown in the radiograph in fig. 15. There is no conspicuous pigmentation. Specimens fixed initially in formaldehyde or alcohol become opaque yellowish white, while black pigmentation becomes visible. Figs. 4b-e, 12 and 14 give an impression of the variability found in the distribution of pigment. In some specimens pigment is entirely absent. Some series consist of specimens with almost the same pigmentation pattern (e.g. MPIL 1291/1299, fig. 4b). Other samples show more variability and may contain specimens with or without distinct dorsal blotches together with specimens with or without the distinct dorsal stripe (fig. 4d-e). The midlateral stripe may also be subject to variation. It should be noted that the pattern and the density of pigmentation can be influenced by the method of preservation. Gymnorhamphichthys hypostomus seems to be characterized by having about 10 to 12 dark brown to black mid- lateral blotches (in alcohol). Although of the six known specimens one (CAS 50679) is poorly pigmented (fig. 3).

ECOLOGY In Surinam, Gymnorhamphichthys rondoni was mostly found in small creeks (width up to about 8 m), with running water and sandy bottoms. It is a sand-dwelling species. The remarkable anterior position of the anal opening enables the to get rid of their excrements without having to leave their buried positions. Lissmann & Schwassmann (1965: 153) provide the following information on Gymnorhamphichthys hypostomus (most likely it refers to Gymnorhamphichthys rondoni, which is the commoner species): "Like all other gymnotids it is a nocturnal . It spends the daylight hours buried in sand and emerges after sunset to swim about actively until shortly before dawn, when it again enters the sand. Correlated with the phases of activity and rest is a marked difference in the frequency of electric organ discharges. It is low when the fish is in the sand, and high when it is freely swimming."

NOTE ON GYMNORHAMPHICHTHYS APURENSIS

Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 Apart from Gymnorhamphichthys hypostomus and G. rondoni as defined in the present paper, there is only one other nominal species described in this genus: Gymnorhamphichthys apurensis Fernandez Yépez, 1968. Assuming that it really belongs to this genus, G. apurensis shows an aberrant colour pattern as compared to G. hypostomus and G. rondoni. Fernandez Yépez' original description provides too little information to clearly recognize Gymnorhamphichthys apurensis as a distinct species. It was based on the GYMNORHAMPHICHTHYS SPECIES FROM SOUTH AMERICA 61

holotype, 354 mm total length (A.F.Y. 51.169), and three paratypes, 316-389 mm total length (A.F.Y. 51.045, 51.251, and 51.079), collected from the Rio Apure, Venezuela (type locality: "... Rio Bucaral (Paso Don Pancho), afluente del Rio Apure"). This size is much larger than the largest known specimen of Gymnorhamphichthys (G. rondoni, 269 mm total length), and approaches the size of a representative of the genus Rhamphichthys. Fernandez Yépez distinguished his species from the others by its relative weight, and by proportions as compared to that of Gymnorhamphichthys hypostomus, sensu Fernandez Yépez. The anal position of Gymnorhamphichthys apurensis is slightly behind the vertical extending from the eye. Fernandez Yépez describes the colour pattern as "marmoleado". He does not give any fin ray counts. Unfortunately, we did not succeed in our attempts to borrow any type material and until a. more thorough description is prepared, we feel that apurensis should be considered a species inquirendae. Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013

Fig. 16. Map of Surinam showing localities where Gymnorhamphichthys rondoni was collected. 62 H. NÜSSEN et al.

SUMMARY

Gymnorhamphichthys hypostomus and Gymnorhamphichthys rondoni are species with considerable variation in the length of the snout and in the position of the anal pore. A total of three hundred and thirty specimens were examined, including the holotype and 9 paratypes of Gymnorhamphichthys hypostomus Ellis, 1912, the single holotype of Urumara rondoni A. de Miranda Ribeiro, 1920, and the holotype and 20 paratypes of Gymnorhamph- ichthys hypostomus petiti Géry & Vu, 1964. A total of 205 specimens were measured: 1 from Bolivia, 34 from Brazil, 125 from Surinam, 13 from Guyana, 6 from Venezuela, and 26 from Colombia. The results are presented mostly in tables and diagrams, with a short discussion of the most variable characters.

RÉSUMÉ Gymnorhamphichthys hypostomus et Gymnorhamphichthys rondoni sont des poissons qui présentent une variation considérable de la longueur du museau et de la position de l'anus. Trois cent-trente specimens ont été éxaminés, y compris l'holotype et 9 paratypes de Gymnorhamphichthys hypostomus Ellis, 1912, l'unique holotype de Urumara rondoni A. de Miranda Ribeiro, 1920, et l'holotype et 20 paratypes de Gymnorhamphichthys hypostomus petiti Géry & Vu, 1964. 205 specimens ont été mesurés, provenant de diverses localités: 1 de Bolivie, 34 du Brésil, 125 du Surinam, 13 de Guyana, 6 du Vénézuela et 26 de Colombie. Les résultats sont présentés surtout sous forme de tableaux et de figures, la discussion ne concernant que les caractères très variables.

RESUMEN Gymnorhamphichthys hypostomus y Gymnorhamphichthys rondoni son especies con una variación considerable de la largura del hocico y de la posición del agujero anal. Trescientos y trenta ejemplares han sido examinados, inclusive el holotipo y nueve paratipos de Gymnorhamphichthys hypostomus Ellis, 1912, el unico holotipo de Urumara rondoni A. de Miranda Ribeiro, 1920, y el holotipo y viente paratipos de Gymnorhamphichthys hypostomus petiti Géry & Vu, 1964. Se había medido un total de 205 ejemplares: 1 originario de Bolivia, 34 del Brasil, 25 del Surinam, 13 de Guyana, 6 de Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013 Venezuela, y 26 de Colombia. Los resultados figuran las más veces en cuadros y diagramas, acompañados de una breve discusión de los rasgos característicos mÿs variables. GYMNORHAMPHICHTHYS SPECIES FROM SOUTH AMERICA 63

LITERATURE

Curra, R. A. & Miranda Ribeiro, P. de, 1961. Notas sistemáticas sobre Urumarã Rondoni Miranda Ribeiro, 1920 (Pisces Gymnotoidei-). Bol. Inst. Oceanograf., vol. I, n° 2, pp. 474-481, figs. 1-2, tab. I. Ellis, M. M. (in Eigenmann, C. H.), 1912. The freshwater fishes of British Guiana, including a study of the ecological grouping of species and the relation of the fauna of the plateau to that of the lowlands. Mem. Carnegie Mus., vol. V, n° I, pp. i-xix, pp. 1-578, figs. 1-39, pls. I-CIII. Ellis, M. M. 1913. The gymnotid eels of tropical America. Mem. Carnegie Mus., vol. VI, n° III, pp. 109-195, figs. 1-33, pis. XV-XXIII. Fernández-Yépez, A., 1968. Contribución al conocimiento de los peces . Evencias, vol. I, n° 20, 8 pp. text, 5 pp. figures. Fernández-Yépez, A., 1968-1969. Peces continentales neotropicales. Evencias, vol. I, n° 21, pp. i-vi, 1-101, figs. 1-27. Fowler, H. W., 1951. Os peixes de água doce do Brasil. Arq. Zool. Est. São Paulo, vol. VI, entr. 3a, pp. 405-625, figs. 448-589. Géry, J. & Vu, T. T., 1964. Gymnorhamphichthys hypostomus petiti ssp. nov. un curieux poisson gymnotoïde arénicole. Vie et Milieu, suppl. n° 17, pp. 485-498, figs. 1-3, pl.I, tab. I. Knöppel, H. A., 1970. Food of Central Amazonian fishes- contributions to the nutrient-ecology of Amazonian rain-forest-streams. Amazoniana, vol. II, n° 3, pp. 257-352, figs. 1-3, tabs. 1-50. Lissmann, H. W. & Schwassmann, H. O., 1965. Activity rhythm of an , Gymnorhamph- ichthys hypostomus, Ellis. Z. vergl. Physiol. vol. 51, pp. 153-171, figs. 1-9. Miranda Ribeiro, A. de, 1920. Peixes (excl. Characinidae). Comm. Linhas Tel. Estr. Matto- Grosso ao Amazonas, Zool., Hist. Nat. Ann. 5, n° 58, pp. 1-15. Address of the Authors: Dr. H. Nijssen, Curator of Fishes and Mr. I. J. H. Isbrücker, Dept. of Ichthyology, Zoologisch Museum, Plantage Middenlaan 53, Amsterdam, The Nether- lands. Dr. J. Géry, Argentonesse, Castels, 24220 Saint-Cyprien, France. Downloaded by [MNHN Muséum National D'Histoire Naturelle] at 01:36 08 May 2013