Diestostemma bituberculatum Signoret 1855
Creators: name: Pinto, Ângelo Parise
name: Mejdalani, Gabriel
name: Takiya, Daniela Maeda
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Cicadellidae
Diestostemma
Diestostemma bituberculatum

description: Diestostemma bituberculatum (Signoret, 1855)
LSID http://zoobank.org/urn:lsid:zoobank.org:act:25310920-DBED-4E7C-8BDE-8F4054B0FD38 (Figures 3–4, 13–14, 17–18, 27–28, 39–40, 48–49, 59–62, 75–77, 88, 93)
Tettigonia bituberculata Signoret, 1855: 528, pl. 21, fig. 19 (description of male and female syntypes from Rio-Negro [BRAZIL. Amazonas State] in NHMW; comparison with D. albipennis, illustration of habitus of the male [?] in dorsal view);— Kirkaldy (1907: 87, as types species of Leucopepla);— Young & Beier (1964: 567, designation of male lectotype);— Evans (1947: 169, mention as type species of Leucopepla);— Metcalf (1965: 469, catalog, as type species of Leucopepla);— Young (1968: 30, mention as type species of Leucopepla);
Leucopepla bituberculata (Signoret, 1855):— Kirkaldy (1907: 12, 87, comb. nov. as type species of Leucopepla);— Melichar (1924: 211, key, redescription of male and female, comparison with D. atropunctulatum);— Metcalf (1965: 470, catalog);— Schmidt (1928: 37, mention as type species of Leucopepla, comparison with D. rubriventris);
Diestostemma bituberculata (Signoret, 1855):— Walker (1858: 241, comb. nov., catalog);— McKamey (2007: 287, catalog, records from Guyana, French Guiana, Brazil, Argentina, and Uruguay based on Metcalf 1965 and Young 1968);— Paradell et al. (2012: 6, question the occurrence in Argentina);
Diestostemma bituberculatum (Signoret, 1855):— Schmidt (1910: 34, 49–50, key, reproduction of the original description);— Young (1968: 32, 35, 38, figs. 21e–f, i, key, illustrations of female sternite VII in ventral view, connective and stylus in dorsal view and aedeagus in lateral view, records from Guyana, French Guiana, and Brazil);— Zanol & Menezes (1982: 16, record from Brazil).
Material examined (3 ♂, 3 ♀). FRENCH GUIANA. [Cayenne Arrondissement]: 1 ♂, 1 ♀, [Régina commune], 23 km SE Roura on Kew Rd, MV Light (04°34’8.10”N, 52°11’09”W, 238 m a.s.l.), 16–17.IV.2007, D.G. Hall & J.E. Eger leg. (FSCA); 2 ♂, [Roura commune], Kaw Mountain Reserve, unpaved logging road, nr. Amazone Lodge, MV Lights and inspection of vegetation (04°32’57.8”N, 52°12’49.7”W, 287 m a.s.l.), II.2005, J.R. Cryan & J.M. Urban leg. (INHS); [Saint-Laurent-du-Maroni Arrondissement]: 2 ♀, [Saül commune], PM-APL, Bélvédère de Saül, Malaise (03°37’22”N, 53°12’57”W, 308 m a.s.l.), 09.IX.2010, SEAG leg. (DZRJ).
Type repository. Lectotype male by subsequent designation (Young & Nast 1963) and paralectotype female in NHMW, examined by photos (©2016, Natural History Museum Vienna, Hemiptera Image Collection / H. Bruckner).
Measurements (mm, n = 5). Females are larger than males; all upper bounds of intervals correspond to females. Total length (from anterior of head to tip of forewings) 19.2–21.9; crown length 2.4–2.9; interocular distance 2.4–2.9; transocular distance 3.8–4.3; distance between compound eye and mesal line 1.3–1.5; distance between ocellus and mesal line 0.9–1.4; pronotal disc maximum width 5.2–6.0; pronotal disc maximum length 3.6– 4.1; forewing length 15.3–17.9; metathoracic femur length 3.7–4.6; metathoracic tibia length 7.1–8.4.
Diagnosis. A large, dorsolaterally white and ventrally realgar colored Diestostemma, with two pronotal humps and small dark areas on the forewing. Males and females of D. bituberculatum can be distinguished from almost all species, except D. cavichiolii sp. nov. and D. rubriventris, by the pronotal disc virtually lacking dark areas. Diestostemma bituberculatum can be distinguished from D. rubriventris by the H-shaped distal SDV of the forewing (Figs. 48–49; distal SDV large and round in D. rubriventris, Figs. 54–55) and from D. cavichiolii sp. nov. by its larger size with total length 19.2–21.9 mm (18.3–20.8 mm in D. cavichiolii sp. nov.), realgar colored venter of abdomen (Figs. 39–40; yellowish-brown in D. cavichiolii sp. nov.), and pronotal humps strongly projected (Figs. 3–4, 18; distinctly less projected in D. cavichiolii sp. nov., Figs. 5–6, 20).
Males can be distinguished from other species of the D. bituberculatum complex by the abruptly anteriorly curved aedeagal process, forming an angle of about 90° in lateral view, bifurcated into a pair of thin, slightly flattened rami in lateral view (Figs. 75–77; aedeagal process gently curved forming obtuse angle, bifurcated into a pair of expanded or slightly expanded flattened rami in the remaining species, Figs. 72–74, 78–86).
Females have the posterior margin of sternite VII trilobed, with mesal lobe strongly projected, extending distally farther than lateral lobes (Fig. 88), which allows separating D. bituberculatum from all species of this complex except D. albinoi sp. nov. Distinguishing female characters between these two species are given under the diagnosis of the latter species.
Distribution. Recorded from the Amazonia Domain in Guyana, French Guiana, and Amazonas State in Brazil. Its occurrence in southern South American countries Uruguay and Argentina, as cited by Metcalf (1965), is a mistake (see below and in Paradell et al. 2012). Very likely, it is an exclusively tropical South American species occurring at the Amazonian formations of the Brazilian subregion (Fig. 93).
Etymology. The specific name bituberculatum is a declinable adjective. This compound word is formed by the Latin numeral prefix bi- (two, double) plus tuberculum (stem tubercul -; noun n., 2nd decl.; small swelling, protuberance) plus the adjectival suffix – atus –a –um (equipped with) in its neuter form. This name, meaning ‘equipped with two bumps or protuberances,’ refers to the two pronotal humps observed in all species of the D. bituberculatum complex and some species of other groups of Diestostemma (e.g., D. nervosum group). Given that this specific name is an adjective and the genus name is neuter in gender, in agreement with article 31.2 of the International Code of Zoological Nomenclature (ICZN 1999) they must agree in gender, thus the correct spelling is D. bituberculatum, which was firstly adopted by Schmidt (1910). McKamey (2007, p. 287) incorrectly catalogued D. bituberculata following his assumption of an “implicit” new combination by Young (1968, p. 32) of the transfer of Tettigonia bituberculata Signoret, 1855 to Diestostemma. This mistake possibly occurred because Young (1968) only presented specific names and not the full combination with the genus-group name or because he did not use the expression “new combination” for this species. However, McKamey (2007) overlooked the key and figure captions in Young’s (1968, p. 35, 38) monograph, where he clearly stated the combination “ D [iestostemma] bituberculatum ”. Nevertheless, Walker (1858, p. 241) had already previously combined this specific name with Diestostemma.
Remarks. This species was originally described from “Rio-Negro” (Figs. 13–14), which researchers would now identify with little doubt as the large river in the Brazilian Amazonia. Metcalf (1965) and Young (1968) cited its occurrence for Argentina and Uruguay, very likely based on the same locality of Rio Negro. Papavero (1994, p. 113) mentioned a longtime confusion among two homonymous Rio Negro localities in South America, one at the Amazonian Basin and the other referring to Rio Negro Province of southern Argentina. Rio Negro is also an important river crossing Uruguay. All of this would lead both Metcalf (1965) and Young (1968) to consider its occurrence in the Pampean biogeographical province and Andean Region either in Argentina or Uruguay. However, there are no records of specimens of this group (D. bituberculatum complex) outside the Amazonian Basin. The southernmost record for D. bituberculatum is located at 03°08’S, and recently records from Argentina were considered doubtful (Paradell et al. 2012). Hence, D. bituberculatum must be removed from the checklists of these countries.
Since the milestone monograph by Young (1968), structures of the male genitalia are used as a source of taxonomic characters for Diestostemma, including the shape of the arms of the connective. However, we observed strong variation in the few males of D. bituberculatum examined (Figs. 61–62), suggesting that other characters should be used in combination with the male genitalia to confirm species identifications.
description: Published as part of Pinto, Ângelo Parise, Mejdalani, Gabriel & Takiya, Daniela Maeda, 2017, Unraveling the white-clothed Diestostemma Amyot & Serville: a taxonomic revision of the American sharpshooters of the D. bituberculatum complex (Hemiptera: Cicadellidae), pp. 135-164 in Zootaxa 4281 (1) on pages 144-145, DOI: 10.11646/zootaxa.4281.1.14, http://zenodo.org/record/816007