Boletín de la Sociedad Zoológica del Uruguay, 2023

Vol. 32 (1): e32.1.3

ISSN 2393-6940

https://journal.szu.org.uy

DOI: https://doi.org/10.26462/32.1.3

ABSTRACT

This is the first record of the rare calanoid copepod

Odontodiaptomus thomseni for Brazil since this species

was described by Brehm (1933) from Uruguay. There

were found 11 individuals in four sampling sites. This

record extends beyond Uruguay River Basin and La Plata

River Basin the distribution of this species.

Keywords: Zooplankton, few records, rare.

RESUMEN

Primer registro de Odontodiaptomus thomseni

Brehm (1933) (Copepoda, Calanoida) en el estado de

Rio Grande do Sul, Brasil. Este es el primer registro del

raro O. thomseni para Brasil desde que esta especie fue

descrita por Brehm (1933) de Uruguay. Este registro se

extiende más allá de la cuenca del río Uruguay y la cuenca

del río La Plata la distribución de esta especie.

Palabras clave: Zooplancton, pocos registros, rara.

The lack of records of freshwater copepod

Odontodiaptomus thomseni led to its inclusion in the

Red List of threatened species (IUCN) category of

data deficient (IUCN, 2022). The first and valid record

for O. thomseni is that of its original description by

Brehm (1933) from Uruguay. Samples taken in 2010

allowed to produce the second record for O.thomseni

in Salto Grande reservoir, which is located in the lower

stretch of the Uruguay River, between Uruguay and

Argentina, within at the La Plata River Basin

(Perbiche-Neves et al, 2012). In this occasion, the

author´s found just three specimens (two males and

one female).

This note presents the first record of O. thomseni

in Guaíba Lake (29º55' to 30º37' S and 50° 56' to 51°

46' W), Rio Grande do Sul state, Brazil, handing an

updated scenario of its geographic distribution

besides the Uruguay River Basin. Also, is the third

official record since its description by Brehm (1933),

confirming its rarity but not too restricted geographic

distribution. The Guaíba Lake is formed mainly by the

rivers Jacuí, Caí, Sinos and Gravataí, which together

drain the second major area of the state, back just to

Uruguay river basin. The Lake has an area of 2,459.91

km², covering the total or partial areas of 14

municipalities, and with an estimated human

population for the basin whith approximately

1,285,614 inhabitants, with a density of 523

inhabitants / km .

Plankton samples were collected on August in

2018, from four sites: site 1 (29°57'46.6"S and

51°20'45.1"W), site 2 (9°58'32.4"S and 51°15'20.1"W),

site 3 (30°00'46.6"S and 51°13'07.5"W), and site 4

(29°56'34.5"S and 51°16'03.7"W) (Fig. 1). The

organisms were collected by vertical and horizontal

hauls with samplings undertaken on each sampling

occasion to form a 300 L composite sample. The

samples were filtered through a zooplankton net (68

μm) and preserved in 4% formalin.

Bol. Soc. Zool. Uruguay (2ª época). 2023. ISSN 2393-6940Vol. 32 (1): e32.1.3

FIRST RECORD OF Odontodiaptomus thomseni Brehm (1933) (COPEPODA,

CALANOIDA) IN RIO GRANDE DO SUL STATE, BRAZIL

1* 2 3 4

Jorge Laço Portinho , Raquel Freiry , Gilmar Perbiche-Neves , and Cristina Stenert

1Departamento de Biodiversidade, Universidade Estadual Paulista (UNESP) Rio Claro, 13506-692,

São Paulo, Brasil.

2Limnosul, Rua Teófilo Souto Maior, 152 – centro, Sapucaia do Sul, Rio Grande do Sul, Brasil.

3Laboratório de Plâncton, Departamento de Hidrobiologia, CCBS, Universidade Federal de São Carlos, São

Carlos, São Paulo, Brasil. E-mail:

4Programa de Pós-Graduação em Biologia de Ambientes Aquáticos Continentais, Instituto de Ciências

Biológicas, Universidade Federal do Rio Grande (FURG), Rio Grande, RS, Brasil.

Fecha de recepción: 5 de enero de 2023

Fecha de aceptación: 2 de mayo de 2023

*Corresponding author: jorgeportinho@gmail.com

JORGE LAÇO PORTINHO et al.

Bol. Soc. Zool. Uruguay (2ª época). 2023. ISSN 2393-6940Vol. 32 (1): e32.1.3

Fig. 1. Records of O. thomseni. The original description by BREHM (1933) was from Uruguay. The circle shows the rediscovered of O. thomseni after 77 years by Perbiche-Neves (2012)

from Salto Grande Reservoir (Uruguay and Argentina) and the squares mark the present new records from Rio Grande do Sul State, South of Brazil.

3FIRST RECORD OF Odontodiaptomus thomseni Brehm

A total of 11 individuals was identified from four sites

analyzed. Three individuals (three males) were

deposited in the Museum of Zoology in the UNISINOS

University (samples MZUNISINOS Cru0001,

MZUNISINOS Cru0002). A general view of the

collected O. thomseni males specimens are shown in

Fig. 2A and B. The taxonomic diagnosis using scanning

electron microscopy as well as light microscope

observations can be found in Perbiche-Neves et al.

(2012).

All four collection points where we recorded O.

thomseni were located on the shores of Lake Guaíba,

which experiences seasonal fluctuations in water

levels and has extensive areas colonized by flooded

arboreal vegetation and aquatic macrophytes. In

2010, Perbiche-Neves et al. (2012) collected

specimens of O. thomseni in the Salto Grande

reservoir, which is located on the border of Uruguay

(Salto Grande Province) and Argentina. The water

quality at the collection site was generally

characterized by deep, warm (> 28 ºC), and well-

oxygenated waters (> 6.00 mg/L) that exhibited high

levels of nutrients (total nitrogen > 611.00 mg/L and

phosphorus > 36.00 mg/L) and phytoplankton

biomass ( > 4.30 mg/L).

Odontodiaptomus (Kiefer, 1936) genera contains

only three species: O. thomseni (Brehm, 1933), O.

michaelseni (Mrázek, 1901) and O. paulistanus

(Wright, 1936). With the exception of O. paulistanus,

the other two species are rare, and we know nearly

nothing regarding their geographical distribution,

biology, and ecological. As mentioned, this is the third

record of O. thomseni. About the congeners, O.

michaelseni have been only recorded in areas close to

the mouth of the Rio da Prata, in Uruguay and

Argentina, and was not found since it is ordinal

description. O. paulistanus

as been recorded in water bodies in the

state of Minas Gerais (Wright, 1936, 1937), Paraná

(Lopes et al., 1997; Lansac-Tôha et al., 2009), and

São Paulo (Matsumura-Tundisi & Tundisi, 2011). Of all

cited studies for O. paulistanus, most part are included

in the La Plata Basin, but few not, are from basins that

run direct to the coast. This new record indicates that

is relatively common in

Brazil, it h

Bol. Soc. Zool. Uruguay (2ª época). 2023. ISSN 2393-6940Vol. 32 (1): e32.1.3

Fig. 2. Odontodiaptomus thomseni from Guaíba Lake, Rio Grande do Sul State, Brazil. A general view of male, and

B right and left fifth legs, frontal view.

JORGE LAÇO PORTINHO et al.

the species has a somewhat broader geographic

distribution, but still quite restricted considering the

continent or the Neotropical Region. This is valid for

the genus Odontodiaptomus, although it has only

three species.

The Neotropical Region support the third richest

diaptomid fauna in the world, with 82 species

(Boxshall Defaye, 2008). In Brazil, there are 57

species of freshwater diaptomids describe at moment.

However, this number is certainly underestimated,

since knowledge of the Brazilian freshwater copepod

fauna is disparate if we consider the artificial and

natural habitats separately. Much of the knowledge we

have about copepods comes from artificial lakes

formed by damming medium and large rivers is large.

In addition, the record of O. thomseni in Guaíba

Lake is part of an environmental consultancy work, in

which the company carried out a regional inventory of

aquatic communities, including zooplankton. Two

important points should be highlighted in this regard: (i)

a good formation of the taxonomist specialist to identify

species in consulting companies, and (ii) the use of

gray literature, which are documents produced in the

governmental, academic, commercial spheres, which

can be published in scientific journals, and contribute to

the knowledge of the species.

JLP was funded by National Program for Post

Doctoral of the Coordination for the Improvement of

Higher Education Personnel (PNPD/CAPES) –

process number 88887. 473604/2020-00, addressed

to postdoctoral fellowship in the Postgraduate Program

in Ecology, Evolution and Biodiversity at São Paulo

State University (UNESP).

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Editor de Sección: Ana Verdi

Bol. Soc. Zool. Uruguay (2ª época). 2023. ISSN 2393-6940Vol. 32 (1): e32.1.3