Rediscovery of the syntypes of Corydoras meridionalis R. von Ihering, 1911 (Teleostei, Siluriformes, Callichthyidae) and designation of lectotype

Rediscovery of the syntypes of Corydoras meridionalis R. von Ihering, 1911 (Teleostei, Siluriformes, Callichthyidae) and designation of lectotype

Heraldo A. Britski^I,II; André L.C. Mendonça^I

^IMuseu de Zoologia, Universidade de São Paulo, Caixa Postal 42.494, 04218-970, São Paulo, SP, Brasil

^IIE-mail: [e-mail]

RESUMO

Os síntipos de Corydoras meridionalis Rodolpho von Ihering, 1911, tidos como desaparecidos da coleção de peixes do Museu de Zoologia da USP, foram encontrados; os exemplares tinham sido identificados como C. ehrhardti Steindachner, 1910, espécie atualmente considerada sinônimo sênior da primeira. O exame desses sintipos permite confirmar a sinonímia proposta. Dados sobre os síntipos são apresentados e comparados com os dados das descrições originais de C. ehrhardti e C. meridionalis, sendo comentadas as poucas diferenças encontradas entre eles. É designado o lectótipo de C. meridionalis e uma fotografia deste é apresentada.

Palavras-chaves: Taxonomia; Bagre; Peixe de água doce Neotropical.

ABSTRACT

Syntypes of Corydoras meridionalis Rodolpho von Ihering, 1911, once regarded as lost, were recently found in the collection of fishes of the Museu de Zoologia da USP. The syntypes had been identified as C. ehrhardti Steindachner, 1910, currently considered a senior synonym of that species. Examination of the rediscovered syntypes corroborates the proposed synonymy. Data on the syntypes are presented and compared with information in the original descriptions of C. ehrhardti and C. meridionalis; a few discrepancies found are discussed. A lectotype is designated for C. meridionalis and a photograph of the specimen is provided.

Keywords: Taxonomy; Catfish; Neotropical freshwater fish.

INTRODUCTION

Corydoras meridionalis was described by Rodolpho von Ihering (1911) on the basis of an unspecified number of specimens; however it is possible to assume that more than one specimen was examined because it is stated in the original description in two languages: "Compr.: até 60 mm." (Portuguese) and "Korperlange: bis 60 mm." (German), meaning that the largest specimen examined had 60 mm of length (possibly total length). The syntype series of C. meridionalis was deposited at the fish collection of the Museu Paulista, now Museu de Zoologia da Universidade de São Paulo (MZUSP). Britski (1969), in a paper dealing with fish types deposited at that institution, informed that he was unable to find the syntypes of C. meridionalis.

Nijssen & Isbrücker (1980) considered Corydoras meridionalis a synonym of C. ehrhardti Steindachner, an action we presume was largely based on Ihering's description of C. meridionalis (whose data mostly agree to those mentioned for C. ehrhardti) and also on the closeness of the type localities of both species in the state of Santa Catarina, Brazil: "Colonia Hansa" for C. meridionalis and "Fluβgebiet des Jaraguá" for C. ehrhardti. Colonia Hansa (now Corupá) is located in the Jaraguá river basin, state of Santa Catarina, Brazil (about 26º21'S 48º29'W). Many authors followed Nijssen & Isbrücker (1980) in considering C. meridionalis as a junior synonym of C. ehrhardti, including recent catalogs and lists by Reis (2003), Ferraris (2007), and Menezes et al. (2007).

In an ongoing revision of the Corydoras collections at MZUSP we were fortunate to find out a lot containing the syntypes of C. meridionalis. The lot containing three specimens was identified as C. ehrhardti and its label includes the following data: "MZUSP 426 Colonia Hansa, Santa Catarina, det. Miranda-Ribeiro, 1918". In the fish collection catalog book of MZUSP the data pertaining to number 426 indicates the collector as W. Ehrhardt. It is clear then that this lot is the same mentioned by Miranda-Ribeiro (1918), where he listed the fishes from the Museu Paulista, with the folloowing remarks: "Corydoras ehrhardti Steind. 4 exemplares. Coll. Hansa, Santa Catharina (n.426 - det. Cor. meridionalis)" (p.721). It is also quite evident that Miranda-Ribeiro indicated that the fishes he identified as C. ehrhardti were previously identified as Corydoras meridionalis.

For some decades after 1914 there was no curator in charge of the fish collection at Museu Paulista. Therefore the museum director at that time sent a large collection of fishes to the Museu Nacional at Rio de Janeiro, where they were examined by Alípio de Miranda-Ribeiro and formed the basis of his 1918 paper listing the fishes that he had identified. Miranda Ribeiro examined the syntypes of Corydoras meridionalis and identified them as C. ehrhardti but unfortunately did not make any other comment about his decision. However, it is reasonable to assume that Miranda-Ribeiro had already considered C. meridionalis as a junior synonym of C. ehrhardti, prior to Nijssen & Isbrücker (1980).

A lectotype for Corydoras meridionalis is herein elected and designated. Data from the lectotypes and two paralectotypes are compared to data taken from the original description of the two species, and a photograph of the lectotype is provided. There is no need to provide a full description of these types as the species (C. ehrhardti) is well known. Therefore only partial comments are made on the data presented, especially about the discrepancies among them.

MATERIAL AND METHODS

Measurements and counts herein used follow Reis (1997) except for head length (measured to posterior most portion of operculum) and number of scutes between dorsal and adipose fin, which is the median dorsal azygous scutes that precede the adipose fin. In addition, the pectoral-fin spine length (ossified portion) and the first pelvic-fin ray length (from base to tip) were also measured. Measurements of the syntypes are expressed in mm. Proportional measurements of the syntypes are expressed as fractions of standard length or fractions of head length, following the original descriptions of Corydoras ehrhardti and C. meridionalis. Measurements and counts were taken on the left side of the specimens whenever possible.

RESULTS

The largest specimen in the syntype series of Corydoras meridionalis (MZUSP 426, 43.6 mm SL) is designated as lectotype (Fig. 1). The other two syntypes (MZUSP 104670, 42.8 mm and 29.3 mm SL) are thus paralectotypes. Data from these types are presented in Table 1 along with all the counts and proportions given by Steindachner (1910) and Ihering (1911) in the original descriptions of C. ehrhardti and C. meridionalis, respectively. Analysis and comparisons of these data as well as those taken from other specimens of C. ehrhardti from different localities of Southeastern Brazil (Comparative material) corroborate that C. meridionalis is a junior synonym of Steindachner's species.

DISCUSSION

The specimens described by Steindachner (1910) as Corydoras ehrhardti were sent to the Vienna Museum by Wilhelm Ehrhardt. Steindachner does -not mention this in his article but the name of the -species was obviously given in honor to its collector. Besides, Lambourne (1995) reported that W. Eh-rhardt collected the types of C. ehrhardti in 1909, ap parently obtaining these data from people in the Vienna Museum. On the other hand, the catalog book of the MZUSP fish section records that the speci mens of C. meridionalis sent to the Museu Paulista by Ehrhardt were collected in 1908. Therefore it is possible that Ehrhardt sent the Corydoras specimens first (1908) to the Museu Paulista and subsequently (1909) to the Vienna Museum. Actually not only specimens of Corydoras but also a collection of fishes represented by about fourteen species collected in 1908 were sent by Ehrhardt from Colonia Hansa (= Corupá) to the Museu Paulista, according to a survey we have recently accomplished. Ehrhardt was a vigorous collector who also sent zoological material from Santa Catarina state to European museums, especially amphibians and reptiles, in addition to fishes and mammals (Gutsche et al., 2007). The two species of Corydoras in question were almost simultaneously published (1910 and 1911), and it is reasonable to suppose that Ihering sent for publication his C. meridionalis unaware of the description of C. ehrhardti by Steindachner.

Another aspect to be considered relates to the number of specimens in the syntype series. As mentioned, R. v. Ihering did not refer to the number of specimens he examined when describing the new species, but it is reasonable to assume he examined more than one; Miranda-Ribeiro informed that he examined four specimens of Corydoras ehrhardti (= syntypes of C. meridionalis) but there are only three specimens in the jar we discovered. Such discrepancy can only be explained by the loss of one specimen from the series examined by Miranda-Ribeiro (1918); or from the original syntype series, if we consider that Ihering described the new species on the basis of those four specimens mentioned by Miranda-Ribeiro. In any case, the loss of fish specimens from lots in the Museu Paulista (= MZUSP) was frequent during the period while the institution did not have a fish curator, and several such cases are reported by Britski (1969).

Although Ihering probably examined more than one specimen of Corydoras meridionalis, he described the species on the basis of only one individual. This can be inferred by the lack of mention of any variation of descriptiove data, as shown in Table 1.

The typical blotches on the body of Corydoras ehrhardti, below the dorsal and adipose fins, are very faint on the lectotype (Fig. 1) and paralectotypes of C. meridionalis, but are undoubtedly present.

Table 1 shows that the data of the lectotype and paralectotypes of Corydoras meridionalis match generally those reported by Steindachner and Ihering, and some minor differences can be attributed to intraspecific variation. The only mismatch of data are the proportions SnL/OD and IW/OD and pectoral-and anal-fin ray counts in Ihering, and the counts of pel-vic-fin ray in both Ihering and Steindachner.

The discrepancy of proportions SnL/OD and IW/OD may be attributed to Ihering's different way (or mistake) in measuring orbital diameter. However, additional specimens of Corydoras ehrhardti of different sizes and localities (see list of Comparative material) were measured and counted, showing great variation in those proportions (1.61-2.26 and 1.41-2.26, respectively) bringing Ihering's data to ours and Steindachner's.

We attribute Ihering's count I+7 for pectoral-fin rays to the difficulty in observing the last rays of that fin that are very weak and covered by relatively thick skin. Accurate counting of those rays can only be made by removing the skin of the basal portion of the rays. Thus the right count for the pectoral fin should be I+8, a count unfortunately not mentioned by Steindachner. Maybe the same explanation could be used for Ihering's anal-fin ray count (6).

The number of pelvic-fin rays mentioned by both Steindachner and Ihering is 7. We have counted always 6 rays (i+5) not only in the syntype series of Corydoras meridionalis but in many other individuals of C. ehrhardti (see list of Comparative material). In addition, according to Nijssen (1970), i+6 pelvic-fin rays is very unusual in Corydoras. So we cannot explain this discrepancy (Table 1), but we can assert that C. ehrhardti commonly has i+5 pelvic-fin rays.

Comparative material of Corydoras ehrhardti from Brazil

São Paulo: MZUSP 70620 (1), Rio Tejuco, near mouth of Rio Ribeira de Iguape at road to Itapirapuã Paulista; Paraná: MZUSP 41812 (2), Rio Negrinho, drainage of Rio Iguaçu; MZUSP 45673 (1), Rio Guabiroba, drainage of Rio Tibagi, Parque Estadual de Vila Velha, Ponta Grossa; MZUSP 81572 (132), Rio Pitangui, tributary to Rio Tibagi, Santa Rita at road Abapã-Castro (BR-090), Castro; MZUSP 71861 (3), Rio Capivari, Fazenda Capivari, Campina Grande do Sul; MZUSP 79689 (5), Rio Verde, Ponta Grossa; Santa Catarina: MZUSP 41709 (6), creek at road Campo Alegre-São Bento do Sul; MZUSP 41797 (6), Rio Lindo at road Pirabeiraba-Campo Alegre (SC-301), Pirabeiraba; MZUSP 37736 (1), creek tributary to Rio Itapocu, Corupá.

ACKNOWLEDGEMENTS

We are indebted to Naércio A. Menezes and José Lima de Figueiredo who provided important suggestions and criticism for the improvement of the manuscript, as well as detailed review of the English. Leandro M. Sousa prepared the photograph of the lectotype of Corydoras meridionalis.

Recebido em: 22.12.2009

Aceito em: 08.03.2010

Impresso em: 31.03.2010

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Publication Dates

• Publication in this collection
  07 Apr 2010
• Date of issue
  2010

History

• Accepted
  08 Mar 2010
• Received
  22 Dec 2009