Male imago description of Americabaetis longetron Lugo-Ortiz & McCafferty (Ephemeroptera: Baetidae), and First Key to adults of the genus

Descrição da imago macho de Americabaetis longetron Lugo-Ortiz & McCafferty (Ephemeroptera: Baetidae) e primeira chave para adultos do gênero

SYSTEMATICS, MORPHOLOGY AND PHYSIOLOGY

Male imago description of Americabaetis longetron Lugo-Ortiz & McCafferty (Ephemeroptera: Baetidae), and First Key to adults of the genus

Descrição da imago macho de Americabaetis longetron Lugo-Ortiz & McCafferty (Ephemeroptera: Baetidae) e primeira chave para adultos do gênero

Frederico F. Salles; Rafael Boldrini

Depto. Ciências da Saúde, Biológicas e Agrárias, Centro Universitário Norte do Espírito Santo, Univ. Federal do Espírito Santo, Rua Humberto de Almeida Franklin, 257, Bairro Universitário, 29.933-415, São Mateus, ES

ABSTRACT

The male imago of Americabaetis longetron Lugo-Ortiz & McCafferty is described based on nymphs reared on field in the municipality Alfredo Chaves, Espírito Santo state, Brazil. The species can be distinguished from the others male imagos of the genus by the following combination of characters: 1) turbinate eyes uniformly separated from each other, upper surface ellipsoidal; 2) terga with a light yellowish brown band along midline; 3) genitalia with first segment distinctly constricted medioapically; 4) length of body relatively long (6.3 mm). The first key to the male imagos of the genus is also proposed.

Keywords: Taxonomy, identification key, Espírito Santo, Neotropics

RESUMO

A imago macho de Americabaetis longetron Lugo-Ortiz & McCafferty é descrita a partir de ninfas criadas em campo no município de Alfredo Chaves, ES. A espécie pode ser diferenciada das outras imagos machos do gênero pela seguinte combinação de características: 1) olhos turbinados uniformemente separados, superfície dorsal elipsoidal; 2) tergitos com linha longitudinal mediana castanho-clara amarelada; 3) primeiro artículo do fórceps com uma constrição medioapical distinta; 4) comprimento do corpo relativamente longo (6,3 mm). É proposta a primeira chave para identificação das imagos machos do gênero.

Palavras-chave: Taxonomia, chave de identificação, Espírito Santo, Neotrópico

Americabaetis Kluge is a widespread Pan-American genus of Baetidae (Ephemeroptera) distributed from Argentina to USA (south Texas) (Domínguez et al. 2006, Wiersema & McCafferty 1999), including also the Antilles (Kluge 1992, Hofmann et al. 1999). Eleven valid species are known from South America, four from the Antilles, two exclusively from Central America and one from Central and North America. Of these 18 species, A. bridarolli (Navás), A. jorgenseni (Esben-Petersen), A. oldendorffi (Weyenbergh), A. peterseni (Hubbard), and A. weiseri (Navás) are known exclusively from adults; A. boriquensis (Lugo-Ortiz & McCafferty ), A. intermedius (Lugo-Ortiz & McCafferty), A. labiosus Lugo-Ortiz & McCafferty, A. longetron Lugo-Ortiz & McCafferty, and A. maxifolium Lugo-Ortiz & McCafferty are known exclusively from nymphs; A. alphus Lugo-Ortiz & McCafferty, A. humilis Hoffman & Thomas, A. naranjoi (Kluge), A. pleturus (Lugo-Ortiz & McCafferty), A. robacki (Lugo-Ortiz & McCafferty), and A. spinosus Hoffman & Thomas are known from nymphs, male and female imagos; whereas A. lugoi Waltz & McCafferty, a parthenogenetic species, and A. titthion are known from nymphs and female imagos (Waltz & McCafferty 1999, Wiersema & McCafferty 1999, Lugo-Ortiz & McCafferty 1996, Kluge 1992, Hofmann et al. 1999, Salles et al. 2004, Domínguez et al. 2006).

A key to the nymphs of Americabaetis described so far was provided by Waltz & McCafferty (1999), and Domínguez et al. (2006) presented a key to the nymphs of South America. However, for the identification of the imagos no key was available until now. The aim of this paper is to present the description of the male imago of A. longetron and to propose the first key to the male imagos of the genus.

Material and Methods

Nymphs of A. longetron were caught on the marginal vegetation of the river, and the adults were obtained by rearing these nymphs in the field. Terms used in descriptions of thorax are from Kluge (1994). The material is deposited in the Entomological Collection of the Universidade Federal do Espírito Santo.

The five species known exclusively from adults (A. bridarolli, A. jorgenseni, A. oldendorffi, A. peterseni, A. weiseri) are not treated in the key once they were tentatively placed in Americabaetis by Lugo-Ortiz & McCafferty (1999). Their original descriptions are old, inadequate and, as pointed out by Domínguez et al. (2006), they cannot be reliably distinguished based on the known characters. A. pleturus and A. naranjoi are keyed together once they cannot be distinguished from each other based on the characters given in the literature. However, A. naranjoi is highly unlikely to be found outside of the Antilles (Wiersema & McCafferty 1999).

Americabaetis longetron Lugo-Ortiz & McCafferty, 1996 (Figs. 1-4)

Americabaetis longetron Lugo-Ortiz & McCafferty, 1996: 165, Domínguez et al., 2006: 70.

Male Imago

Diagnoses. The male imago of A. longetron can be distinguished from others species of the genus by the following combination of characteristics: 1) turbinate eyes uniformly separated from each other, upper surface ellipsoidal (Fig. 1); 2) terga with a light yellowish brown band along midline (Fig. 3); 3) genitalia (Fig. 4) with first segment distinctly constricted medioapically; 4) body relatively long (6.3 mm).

Description. Body length: 6.3 mm. Forewings: 5.1-5.8 mm. General coloration reddish brown.

Head (Fig. 1). Light yellowish brown with V shaped brown mark; ocelli surrounded with brown. Antennae whitish, scape and flagellum slightly washed with brown. Turbinate eyes uniformly separated from each other, upper surface ellipsoidal, orangish; basal half of stalk brown, paler toward apex, apical half light yellowish brown.

Thorax . Pro and metanota brown; mesonotum brown with light yellowish brown mark on anteronotal transverse impression, light yellowish brown along lateroparapsidal suture, posterior scutal protuberance dark brown. Legs whitish. Leg I: tibia 1.5 times the length of femur, tarsi subequal in length to the femur and with four segments decreasing in length apically. Legs II and III: tibia subequal in length to the femur, tarsi 0.35 times the length of femur. Wings with small stain of yellowish brown (Fig. 2); membrane hyaline except for costal and subcostal area translucent; longitudinal veins light brown, transversal veins whitish.

Abdomen (Fig. 3). Terga brown, light yellowish brown band along midline; segments 2 to 7 with anterolateral light yellowish brown marks as in Fig. 3; posterior margin of segments 1 to 7 dark brown. Sterna light brown, lateral margins brown. Genitalia (Fig. 4) light brown, third segment whitish; first segment distinctly constricted medioapically. Cerci whitish, segments apically surrounded with brown.

Material examined. Three male imagos (reared): Brazil, Espírito Santo, Alfredo Chaves, Nova Mantova, S 20º39'22", W 40º50'13", 13.x.2007, R. Boldrini col.; 1 male imago (reared): same locality, 04.xi.2007, same collector.

Key to the Male Imagos of Americabaetis

1. Upper surface of turbinate eyes circular; marginal intercalary veins often single......................................................................................A. humilis (West Indies: Guadalupe)

1'. Upper surface of turbinate eyes ellipsoidal; marginal intercalary veins often double.............................................2

2(1'). First segment of forceps distinctly constricted medioapically..................................................................................3

2'. First segment of forceps not constricted medioapically..4

3(2). Turbinate eyes uniformly separated from each other; terga with a light yellowish brown band along midline..........A. longetron (South America: Brazil, Paraguay and Uruguay)

3'. Turbinate eyes anteriorly divergent; terga not as above....A. pleturus (Central and North America: Costa Rica, Nicaragua, Belize, Honduras, Mexico and USA) / A. naranjoi (Cuba)

4(2'). Base of second segment of forceps dark, remainder of genitalia pale.............A. spinosus (Guadalupe, West Indies)

4'. Genitalia not as above; distributed in South America...5

5(4'). Turbinate eyes uniformly and widely separated from each other.................................................................................A. alphus (Argentina, Bolivia, Brazil, Chile and Paraguay)

5'. Turbinate eyes closely separated from each other, anteriorly divergent.............A. robacki (Peru and Uruguay)

Acknowledgments

Financial support from Fundação de Apoio à Ciência e Tecnologia do Espírito Santo (FAPES) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) is acknowledged.

Received 01/II/08. Accepted 18/IX/08.

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• Waltz, R. & W.P. McCafferty. 1999. Additions to the taxonomy of Americabaetis (Ephemeroptera: Baetidae): A. lugoi, n. sp., adult of A. robacki, and key to larvae. Entomol. News 110: 39-44.
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Publication Dates

• Publication in this collection
  01 Dec 2008
• Date of issue
  Oct 2008

History

• Received
  01 Feb 2008
• Accepted
  18 Sept 2008