Rhinoleucophenga joaquina sp. nov. (Diptera: Drosophilidae) from the Neotropical region

Rhinoleucophenga joaquina sp. nov. (Diptera: Drosophilidae) da região Neotropical

SYSTEMATICS, MORPHOLOGY AND PHYSIOLOGY

Hermes J Schmitz^I; Marco S Gottschalk^II; Vera L S Valente^{I, II}

^IPrograma de Pós-Graduação em Genética e Biologia Molecular; [e-mail]; [e-mail]

^IIPrograma de Pós-Graduação em Biologia Animal, Lab. Drosophila. Univ. Federal do Rio Grande do Sul, C. postal 15053, Av. Bento Gonçalves 9500, Bloco B, Prédio 43323, sala 210, Agronomia, 91501-970, Porto Alegre, RS; [e-mail]

ABSTRACT

The genus Rhinoleucophenga Hendel comprises 18 nominal species and has a Neotropical and Nearctic distribution. A new species was found in a collection in Florianópolis, SC, Brazil, and is described as Rhinoleucophenga joaquina sp. nov. The specimens found were reared from flowers of Dyckia encholirioides (Bromeliaceae), collected in a region of restinga on the dunes. The use of flowers as breeding site for Rhinoleucophenga has never been reported before.

Key words: Taxonomy, new species, Steganinae, Insecta, Brazil

RESUMO

O gênero Rhinoleucophenga Hendel compreende 18 espécies nominais e possui distribuição Neotropical e Neártica. Uma nova espécie foi encontrada em coleta realizada em Florianópolis, SC, e é descrita como Rhinoleucophenga joaquina sp. nov. Os espécimes encontrados emergiram de flores de Dyckia encholirioides (Bromeliaceae) coletadas em região de restinga sobre dunas. Este é o primeiro registro da utilização de flores como sítio de oviposição para Rhinoleucophenga.

Palavras-chave: Taxonomia, nova espécie, Steganinae, Insecta, Brasil

Rhinoleucophenga Hendel is a genus with Neotropical and Nearctic distribution and currently comprises 18 nominal species. This genus is classified in the subfamily Steganinae, tribe Gitonini and subtribe Acletoxenina (Grimaldi 1990). It was erected by Hendel (1917) and new species were included by Duda (1927, 1929) and Malogolowkin (1946). Additionally, the genus Pseudophortica Sturtevant was synonymized under Rhinoleucophenga by Malloch & McAtee (1924), one species was transferred from Drosophila Fallén to Rhinoleucophenga by Vilela (1990) and the five American species originally described as Gitona Meigen are currently allocated in this genus by some authors (Brake & Bächli 2008).

The taxonomy and biology of species of this genus are poorly known. As result of our efforts to survey Drosophilidae species associated with living flowers, an undescribed species of Rhinoleucophenga was found in the dunes of Joaquina beach, in Florianópolis (SC), southern Brazil. This species is described in here.

Material and Methods

The new species described in here was reared from flowers of a terrestrial bromeliad, Dyckia encholirioides (Bromeliaceae), collected at the Parque Municipal das Dunas da Lagoa da Conceição, in the municipality of Florianópolis, state of Santa Catarina, Brazil (27°38'S; 48°28'W), on the 28^th of October, 2006. The park comprises a region of coastal sand dunes and restinga vegetation between Joaquina Beach and a coastal lagoon (Lagoa da Conceição), in the Santa Catarina Island, southern Brazil. The plant species was identified by one of us (HJS), and constitutes one important element of the flora of the shrubby restinga of the region (Falkenberg 1999).

One hundred living flowers at the stage of anthesis were collected, and separated from the axis of the inflorescence of D. encholirioides. The collection was carried out in the inner stable dunes, covered with herbaceous and brushy vegetation, in the western portion of the park. The flowers collected were taken into plastic bags to the laboratory, transferred to vials with vermiculite and kept in a temperature-controlled room at 25°C. Twenty days later, six individuals of an undescribed species of Rhinoleucophenga emerged from the flowers, and another one emerged the day after. All seven specimens were males. No other insect emerged from the flowers.

The specimens were aged for 3-4 days after emergence and placed in ethanol: distilled water: acetic acid: glycerol (6:4:1:1). Measurements were taken with a reticle adjusted to an optical stereomicroscope. Male terminalia were disarticulated after treatment with 10% potassium hydroxide (KOH) and acid fuchsine (Wheeler & Kambysellis 1966, modified by Bächli et al 2004), and dissected in glycerol. Photos were taken with a digital camera coupled to an optical stereomicroscope, and drawings of male terminalia were made with a camara lucida attached to an optical microscope with a 10 x objective lens and a 10 x ocular lens.

The terminology follows Vilela (1990) and Bächli et al (2004). The measurements are given by averages followed by the ranges in parentheses.

The type-series was deposited in the Museu de Ciências Naturais (MCNZ), Fundação Zoobotânica do Rio Grande do Sul, Porto Alegre, RS, Brazil. The specimens were pinned (double-mounted) and the disarticulated terminalia kept in microvials with glycerol, with the respective specimens. Before pinning, the specimens were dried with 100% ethanol, ethylene glycol and xylene, as described by Bächli et al (2004). Herbarium vouchers were deposited in the Herbário ICN, at the Universidade Federal do Rio Grande do Sul, Porto Alegre.

Rhinoleucophenga joaquina sp. nov.

Type series. Male holotype labelled "Rhinoleucophenga joaquina; HOLOTYPE B&; Brasil, Santa Catarina, Florianópolis, Joaquina; 27°38'S; 48°28'W; 28.x.2006 col.: H J Schmitz; ex: flores de Dyckia encholirioides". Six male paratypes labelled "Rhinoleucophenga joaquina; PARATYPE B&; Brasil, Santa Catarina, Florianópolis, Joaquina; 27°38'S; 48°28'W; 28.x.2006 col.: H J Schmitz; ex: flores de Dyckia encholirioides". Postabdomen of holotype and two of the paratypes dissected, stored in microvials with glycerin, together with the respective specimen.

Type locality. Joaquina, Florianópolis, Santa Catarina, Brazil.

Diagnosis. Head and thorax mainly brownish. Aristae microtrichose, with ca. 10-15 very short dorsal branches and no ventral branch. One strong pair of prescutellar acrostichal setae. Legs yellow, wings hyaline. Abdomen yellow, with black, medially interrupted marginal bands on tergites and a medial black stripe extending from the tip of the abdomen to tergite III or IV. Male terminalia as in Fig 1.

Description. Male. Head. Frons brownish, covered with ca. 9 (8-12) frontal setulae in each side and ca. 48 (35-54) scattered interfrontal setulae, frontal length 0.62 (0.60-0.64) mm; frontal index 1.12 (1.03-1.28), top-to-bottom width ratio 1.18 (1.10-1.24). Ocellar triangle brown and prominent, around 35% (28-43%) of frontal length. Orbital setae black, distance of or3 to or1 70% (60-82%) of or3 to vtm, or1/or3 ratio 1.29 (0.63-1.87), or2/or1 ratio 0.30 (0.19-0.45), postocellar setae 14% (12-17%) and ocellar setae 52% (45-73%) of frontal length, vt index 0.67 (0.60-0.76). One pair of large vibrissae, vibrissal index 0.28 (0.19-0.42). Face brown. Carina prominent, nose-like, broadened downwards. Cheek index 4.69 (4.0-6.12). Eye index 1.32 (1.26-1.45). Occiput brownish, paler medially. Antennae brownish. Aristae minutely pubescent, with ca. 10-15 very short dorsal branches and no ventral branch (Fig 3). Proboscis yellow. Palpus brownish, with ca. 20 black setae along lower margin.

Thorax length 1.85 (1.62-2.00) mm. Scutum homogeneously brown or with three faint longitudinal stripes slightly darker (Fig 4); more than 10 irregular rows of acrostichal setulae. One strong pair of prescutellar acrostichal setae, about 59% (54-64%) of posterior dorsocentral setae. Transverse distance of dorsocentral setae 4.22 x (3.75-5.00 x) of longitudinal distance, dc index 0.45 (0.42-0.51). Scutellum brown, distance between apical scutellar setae about 82% (67-100%) of that between apical and basal one; basal scutellar setae divergent; scut index 1.05 (0.97-1.13). Just one pair of postpronotal setae. One pair of proepisternal setae, about 65% (50-78%) of postpronotal setae. Pleura brown, sterno index 0.96 (0.86-1.08), median katepisternal setae absent. Halteres whitish. Legs yellow.

Wings hyaline, veins yellow; length 3.03 (2.88-3.19) mm, length to width ratio 2.18 (2.09-2.28). Indices: C, 3.02 (2.84-3.31); ac, 1.30 (1.18-1.50); hb, 0.53 (0.40-0.60); 4C, 1.01 (0.97-1.15); 4v, 2.35 (2.16-2.59); 5x, 1.54 (1.39-1.62); M, 0.85 (0.81-0.96); prox. x, 0.92 (0.84-1.04).

Abdomen yellow, with black, medially interrupted marginal bands on tergites and a medial black stripe extending from the tip of abdomen to tergite III or IV (Fig 5).

Body length 4.59 (4.22-4.80) mm.

Terminalia (Fig 1). Surstyli fused to epandrium, in each side with 18-19 black rod-shaped prensisetae slightly round at tip. Decasternum absent. Hypandrium width greater than length. Aedeagus as a ring, dorsoventrally flattened, with two terminal processes linked to aedeagal apodeme in the anterior region. Paraphysis long, erect, dorsoventrally flattened, slightly shorter than aedeagus, bearing three setulae at tip, beyond three or four setulae placed subdistally (the latter missing in the holotype). Aedeagal apodeme long and rod-shaped.

Female. Unknown.

Etymology. The species name refers to its type locality, the dunes of Joaquina beach.

Distribution. Known only for the type locality.

Biology. Bred from flowers of Dyckia encholirioides.

Discussion

Rhinoleucophenga joaquina sp. nov. will not fit or will run wrongly in the available keys to Drosophilidae genera. It runs to Gitona in several of them (Sturtevant 1921, Patterson & Mainland 1944, Wheeler 1952, Bächli et al 2004) due to its unusual micropubescent aristae, contrasting to the plumose aristae of most of its congeners. If the micropubescent aristae are not taken into account and are treated as plumose, this species runs to Rhinoleucophenga in the keys of Sturtevant (1921), Malloch & McAtee (1924), Wheeler (1952, 1987) and Okada (1989). In the key of McAlpine (1968) for Drosophilidae genera with bare or micropubescent aristae, it runs to "Nearctic species assigned to Gitona" (but the mesonotum is not spotted). The traditional circumscription of Rhinoleucophenga comprises only species bearing plumose aristae. However, several authors pointed out that the Neotropical and Nearctic species that have bare or micropubescent aristae which were assigned to Gitona, were actually incorrectly placed (McAlpine 1968, Wheeler & Takada 1971, Ashburner 1981, Bächli et al 2004, but see Grimaldi 1990 for a different opinion), and are classified as Rhinoleucophenga in the world catalogue of Brake & Bächli (2008). These species are R. americana (Patterson), R. bivisualis (Patterson), R. brasiliensis (Costa Lima), R. fluminensis (Costa Lima) and R. sonoita (Wheeler). Here, we also adopted a wider circumscription of Rhinoleucophenga, in agreement with Brake & Bächli (2008), including these species and the newly described R. joaquina sp. nov. in the genus Rhinoleucophenga instead of Gitona.

The morphological characters of R. joaquina sp. nov. fit well into the diagnosis of the genus provided by Malogolowkin (1946). In addition, it does not have the thorax spotted as Gitona. Furthermore, the analysis of male terminalia confirmed its identity as a Rhinoleucophenga species. It differs from all of its congeners by its colour pattern, the micropubescent aristae and the male terminalia (in comparison with the descriptions in Duda 1927, 1929, Patterson 1943, Malogolowkin 1946, Costa Lima 1935, 1937, 1950, Wheeler 1949, 1952, Wheeler & Takada 1971, Vilela 1990). Although the male terminalia were not described for most of the species of the genus, R. joaquina sp. nov. clearly differs from all the other species by its colour pattern, especially the abdominal medial black stripe, and by the micropubescent aristae, contrasting with the clearly plumose aristae of almost all of its congeners. Furthermore, it is also very different from other species of the genus with micropubescent aristae. It differs from all of them by the abdominal medial black stripe, and from R. americana, R. bivisualis and R. sonoita in not having the thorax spotted. The aristal morphology is also quite different: at least R. bivisualis and R. brasiliensis clearly have ventral branches (Costa Lima 1937, Patterson 1943), which are lacking in R. joaquina sp. nov.

The lack of more detailed information on species of this genus, especially on male terminalia morphology, makes difficult to establish the relationships of R. joaquina within the genus.

The ecology of Rhinoleucophenga is also badly known. Rhinoleucophenga americana and R. sonoita were recorded to breed in cacti (Wheeler 1952). Rhinoleucophenga obesa (Loew), R. brasiliensis and R. fluminensis are known to prey on coccids during the larval stage (review in Ashburner 1981). Sturtevant (1921) mentioned having examined specimens of R. obesa collected "on persimmons". The presence of Rhinoleucophenga in flowers has never been reported. Although we have collected flowers of many other species of plants in order to obtain drosophilids in Joaquina dunes as well as in other sites, no other specimen of R. joaquina sp. nov. was found. Its biology remains obscure. If it is a host-specific flower-breeding species or if it can exploits other breeding sites remains unknown.

Acknowledgments

The authors thank to the two referees for valuable contributions. This research was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).

Received 17/III/08.

Accepted 08/IX/09.

Edited by Marcelo Duarte - MZ/USP

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Rhinoleucophenga joaquina sp. nov. (Diptera: Drosophilidae) from the Neotropical region

Rhinoleucophenga joaquina sp. nov. (Diptera: Drosophilidae) da região Neotropical

Publication Dates

• Publication in this collection
  29 Jan 2010
• Date of issue
  Dec 2009

History

• Received
  17 Mar 2008
• Accepted
  08 Sept 2009