Introduction

The genus Aleuas includes a few species found in the southern part of South America. Its species are very distinctive: they cannot be mistaken for those of any other South American genus. Together with the genus Zygoclistron, they constitute the tribe Aleuasini of the Copiocerinae, as defined by Amedegnato (1974). The general aspect of Aleuas species is different from those of Zygoclistron, mainly because of the green or yellowish color and rather smooth integument of most species; those of Zygoclistron being mostly brown to straw-yellow, and their integument rugose. Also the color-pattern of the species of Zygoclistron is very different from that of the species of Aleuas.

For the making of the present revision, the types of all the described species were examined and compared with specimens recently collected. Among the latter, representatives of four undescribed species were found.

Materials and methods

Materials.— Most of the specimens used for this work have been collected by the author. Others were borrowed from the Academy of Natural Sciences of Philadelphia and the Museu Nacional de Rio de Janeiro. All existing types of the species previously described have been studied and photographed and some have been compared with specimens in the collection in Montevideo. Methods employed were those usual in taxonomic studies:

Genitalia.— For some of the types and many other specimens these have been dissected, cleaned in a solution of KOH and preserved in glycerin. Details of the cleaning and preparation of genitalia are recorded in Carbonell 2004: 64.

Measurements.— Measures were taken with a sliding stage, its displacement registered by an attached dial caliper. Accuracy is in the range of 1/10 of a millimeter. These measurements are indicated in Fig. 36.

Colors.— Colors named (number designation in parens) according to the nomenclature given in Smithe (1975), have been used to compare to the colors of the specimens. These names are given as a general indication since tones and hues may vary in different specimens of the same species.

Genus ALEUAS Stål 1878 Figs 1, 37

Fig. 1.

Genera Aleuas and Zygoclistron, differences most visible on head and pronotum indicated by arrows. A. Head frontal. B. Transverse section of metazona. A. vitticollis, male, from Argentina, Corrientes, Arroyo San Joaquin. Zygoclistron trachystictum, male, from Paraguay, Dept. Caaguazú, near Ihú. Scale line 5 mm.

Etymology.—The derivation is probably Alevas or Aleuas, the name of a tyrant in ancient Thessaly.

Size.—Among the specimens measured for this work, the largest male belongs to A. vitticollis, with a total length of 35.8 mm, the smallest to A. curtipennis (22 mm); among the females, the largest is A. albinae (60 mm) and the smallest A curtipennis (32.1 mm). See Tables 1 to 8.

Caryology.—The species of Aleuas whose caryology have been studied have the following chromosomic formulae (Mesa et al. 1982:520):

Note that the only species with 2n=22 is A. paraguayensis, all the others having 2n=20.

Origin.—The center of origin of the genus seems to be that part of southern S. America that includes northern and central Argentina, East Paraguay and the Brazilian states of Mato Grosso and Mato Grosso do Sul. In this area occurs the largest number of species of the genus.

Distribution.— (Fig. 37). According to the data in the literature and by my own observations, the species of Aleuas have been found in southern South America east of the Andes, between parallels 14° 25′S (Diamantino, in State of Mato Grosso, Brasil,) and the province of Chubut in Argentina (approx. 44°S). Within this large territory, the concrete localities from which specimens of these insects have been available for this study or are mentioned in the literature, allow me to indicate the following geographical areas where species of this genus might be present. Those marked with an asterisk (*) are the ones where the species have been actually found:

Habitat.— There are few observations on the habitat of these species, which are found mostly in grasslands and other rather open plant formations. In the complex of acridoid species that is found in the mentioned area, the species of Aleuas are neither common nor abundant. On the map of Cabrera and Willink (1973) of the Botanical Provinces of South America it can be seen that the area occupied by this genus, as defined above, includes parts of the provinces of Cerrado, Paranense, Chaqueña, Espinal, Pampeana, Monte and Patagonica. All these biogeographical provinces have open areas covered with grasses and other herbaceous plants where the species of this genus are found. Some, as the Pampeana, are mostly grassland. Ronderos et al. (1981: 74) mention A. lineatus and A. vitticollis as belonging to the grassland acridid fauna; Sanchez says likewise (1981: 228–9), but also states that neither was numerically abundant in that plant formation.

Food-plants.—My own observations indicate that A. lineatus feeds on grasses (Gramineae or Poaceae) and probably also on Cyperaceae. A. vitticollis and A. albinae live in dense associations of grasses (see below) where they probably do not have ready access to plants of other families. COPR (1982: 181) states that A. lineatus feeds on natural grasses, lucerne or alfalfa (Medicago sativa) and also on other (undetermined) cultivated plants. Gangwere and Ronderos (1975: 178), with reference to A. lineatus and A. vitticollis, state that their mandibles are of the graminivorous type, that their feces contain mostly residues of grasses, and that they are unselectively polyphagous. Liebermann (1948: 88, 1950: 10, 1967: 109), Sanchez and De Wysiecki (1993: 31), mention that A. lineatus is frequently found in cultures of alfalfa, but also on prairie dominated by Stipa brachychaeta, and on millet (Panicum miliaceum). I have no data on the food of other species, but the fact that they generally live on grasslands may point to similar feeding habits.

Pathology.— All data on this subject refer to A. lineatus. Luna et al. (1981: 245) say that it is susceptible to infection with Nosema locustae (Microsporida, Nosematidae). Lange and De Wysieki (1996:27) did not find infection with that pathogen in one population of this species. Lange (1992) did not find specimens attacked by Perezia diochroplusiae (Microspora, Pereziidae) or Nosema locustae in Prov. of Buenos Aires. The same author (1996: 108) discovered that A. lineatus is apparently resistant to the fungus Entomophaga grylli, that attacks other grasshoppers.

Taxonomy.— Most of the morphological characters of the species of this genus can be seen in the corresponding illustrations. Only a few of these features that are considered generically important will be mentioned here. Integument smooth on head, abdomen and legs; from impresso punctate to slightly rugose on pronotum. Head globose, slightly opisthognathous; antennae filiform; fastigium very short and blunt in some species, angular in others, always shorter than the width of interocular space. Pronotum: prozona longer than metazona in most known species, equal to it in A. albinae; median dorsal carina from slightly elevated to almost obsolete, lateral carinae absent; anterior margin evenly rounded to almost straight, posterior margin either rounded or slightly angulate in different species; prosternal tubercle spiniform, slightly retrorse. Tegmina and wings from well-developed and reaching or surpassing end of abdomen, to reduced to a variable extent, this more frequently in females than in males.

Fore and middle legs without particularities, the hind with carinae well-marked, smooth; hind tibiae with 7 to 9 external spines (exceptionally 6 or 10) and 8 to 10 internal ones (exceptionally 12); some in the apical part modified, as a part of the stridulatory apparatus. Intermesosternal space closed or very narrowly open in males, open in females; intermetasternal space closed in males, open in females. General coloration green in some species, light brown in others; some species having green and brown forms.

Stridulatory mechanism. (Fig. 35) This apparatus and the sounds produced are described in detail by Lorier et al. (2002). It consists of modified spines on the internal side of the distal end of the hind tibiae, which are almost parallel to the tibial axis, and modified cross veins on the radial area of the tegmen, elevated over its general surface. Stridulation is produced by rapid movements of the hind tibia that run its modified apical spines over the said veinlets. The sounds produced are not very loud. Species of Zygoclistron have the same type of stridulating apparatus, but it is worth mentioning that, while the raised crossveins on the tegmina are very conspicuous, in that genus there are no modified spines on the hind tibiae; the normal spines seem to effect that function. A. curtipennis and A. uruguayensis lack the stridulatory mechanism.

Key to species of the genus Aleuas.

Males

Females

Aleuas albinae n.sp. Figs 2, 3, 20, 21, 22, 23, 25B, 27, 37. Table 1

Fig. 2.

Aleuas albinae n. sp. habitus. Male from Uruguay, Dept. Florida, Casupá. Length 41.8 mm. Scale line 5 mm.

Fig. 3.

Aleuas albinae n. sp. habitus. Female from Uruguay, Dept. Florida, Casupá. Length 60.2 mm. Scale line 5 mm.

Etymology.— Specific name dedicated to my wife Albina, without whose help much of my work could not have been done.

Taxonomy.— One of the largest species (Table 1). Fastigium in dorsal view projected forwards in a very obtuse angle; frontal margin of pronotum almost straight, slightly curved; sides of posterior margin in an almost right angle (Fig. 22); median carina of pronotum very slightly marked. Male cerci strongly incurved, with spatulate apices (Fig. 25), a character shared within the genus only with A. lineatus, but found in most species of Zygoclistron. Furculae of the 10th abdominal segment of males absent in this species (and in A. lineatus), though present in all the other species (Figs 25, 26). Stridulatory mechanism with three modified spines on hind tibiae in both sexes (as in A. paraguayensis, Fig. 35). Phallic complex (Fig. 27): characteristic are the massive apical valves of the endophallus.

Chromatic characters.— General coloration light apple-green (61). Dusky-brown (19) lateral postocular bands continued on sides of pronotal disk; a white (slightly yellowish) band immediately below it on prozonal lateral lobes, that disappears on metazona; lower margins of lateral lobes narrowly fringed with white. Fore and middle legs light cinnamon; hind femora apple-green (61) with upper surface yellow in females, black markings on internal side (female) as shown in Fig. 23. Hind tibiae and tarsi vinaceous (4).

Affinities.—This species seems very closely related to A. lineatus, from which, however, it can be readily separated by its much larger size and other characters as indicated in the respective descriptions and in the keys.

Habitat.— The habitat of this species is the same as described below for A. vitticollis. Like the latter species, it is nocturnal and, being far less common, it is almost impossible to find specimens in the daytime. Unlike A. vitticollis, all specimens, male and female, are long-winged; we have never found a short-winged individual.

Known distribution.— (Fig. 37). Uruguay: probably most of the country. The nocturnal habits of this species, its restricted habitat and the fact of its being rather scarce, make its presence probable in areas of Argentina and Brasil where it has not been found to date.

Aleuas curtipennis Bruner 1911 Figs 4, 5, 20, 21, 22, 23, 26D, 28, 37, Table 2

Fig. 4.

Aleuas curtipennis Bruner 1911, habitus. Male from Brazil, Mato Grosso, Chapada dos Guimaraes. Length 22.5 mm. Scale line 5 mm.

Fig. 5.

Aleuas curtipennis Bruner 1911, habitus. Female from Brazil, Mato Grosso, Chapada dos Guimaraes. Length 32 mm. Scale line 5 mm.

Etymology.— Latin, curtus, short and penna, wing or feather.

Taxonomy.— A small-sized species (Table 2). Fastigium in dorsal view projected forwards in an obtuse angle; pronotum with tegument rugose, anterior margin evenly curved, posterior with sides in an obtuse angle (females) or an almost right angle (males), median dorsal carina marked, more prominent in females than in males (Figs 21, 22). Both sexes short-winged, tegmina reaching to about middle of abdomen. End of abdomen in males (Fig. 26): furculae prominent, triangular, divergent; epiproct with an acute caudal projection; cerci conical, short, slightly incurved, not surpassing end of epiproct. Without stridulatory mechanism. Phallic complex (Fig. 28): apical valves of archendophallus in dorsal view mark the most important difference with other species.

Chromatic characters.— General coloration from raw-umber (23) on its darker parts, to buff (24) on lighter ones. Antennal segments mostly fuscous (21), narrowly banded with buff (124) at their apices: area of contact of metathoracic epimeron-episternum black; tegmina with buff (124) veins over a much darker (brown) membrane. All legs mostly buff (124), hind tibiae carmine (8). Inner side of hind femora in females widely marked with black (Fig. 23).

Affinities.— This seems most closely related to A. uruguayensis, these two species lacking the stridulatory mechanism present in all the other species.

Habitat.— Low places with herbaceous vegetation and shrubs.

Known distribution.— Brasil: Mato Grosso, Mato Grosso do Sul and Goias. For what we know of the distribution of the species of Aleuas, this is the northernmost, being recorded between parallels lat 14° 24′S (Diamantino, Mato Grosso) and lat 19° 01′S (Corumbá, Mato Grosso do Sul) (Fig. 37).

Aleuas gracilis Stål 1878 Figs 6, 7, 20, 21, 22, 24, 26B, 29, 37, Table 3

Fig. 6.

Aleuas gracilis Stål 1878, habitus. Male from Brazil, Minas Gerais, between Uberaba and Araxa. Length 32 mm. Scale line 5 mm.

Fig. 7.

Aleuas gracilis Stål 1878, habitus. Female from Paraguay, Dept. Paraguarí, Sapucay. Length 44.9 mm. Scale line 5 mm.

Etymology.— Latin, gracilis, slim, slender.

Taxonomy.— Males small-sized, females considerably larger (Table 3). Fastigium in dorsal view projecting forwards, its sides forming a right angle (slightly acute in some specimens). Disk of pronotum with anterior margin curved, posterior one with sides in an obtuse angle, apex rounded; median dorsal carina well-marked, somewhat prominent in females. Tegmina reaching almost end of second abdominal segment in females, nearly apex of abdomen in males; end of male abdomen (Fig. 26): furculae placed close together, their inner margins contiguous; epiproct triangular, acutely pointed; cerci conical, very slightly incurved, not surpassing end of epiproct. Stridulatory mechanism with two modified pre-apical spines on hind tibiae in males and females. The latter have abbreviated tegmina lacking the corresponding stridulatory crossveins; this might mean that there are also long-winged females, as in the case of A. vitticollis, where the stridulatory apparatus may be functional. Phallic complex (Fig. 29): apical valves of endophallus arch in dorsal and lateral views are characteristic.

Chromatic characters.— General color of body and legs light tawny (38). Postocular bands chestnut (32), continued on upper parts of lateral lobes of pronotum and on tegmina; in females a narrow median band of same color along median dorsal carina of pronotum, continued on terga of metanotum and first abdominal segment; caudal margins of abdominal segments narrowly margined with same color. Tegmina of males very pale apple-green (61) on area above R veins (cubital and vannal areas). Inner pagina of hind femora in females narrowly marked with black, this mark much wider and darker in males; hind tarsi in both sexes superiorly red, this color also on apices of hind tibiae.

Affinities.— Seems closely related to A. vitticollis.

Habitat.— Grassland with shrubs.

Known distribution.— Brasil: Mato Grosso do Sul. Paraguay: eastern part (Fig. 37).

Aleuas lineatus Stål 1878 Figs 8, 9, 20, 21, 22, 24, 25A, 30, 37. Table 4

Fig. 8.

Aleuas lineatus Stål 1878, habitus. Male from Argentina, Prov. Chaco, Arroyo Palometa at National Route 11. Length 31.5 mm. Scale line 5 mm.

Fig. 9.

Aleuas lineatus Stål 1878, habitus. Female from Argentina, Prov. Chaco, Arroyo Palometa at National Route 11. Length 40.3 mm. Scale line 5 mm.

Etymology.— From Latin, linea, thread or line, referring to the dark lines on pronotum.

Taxonomy.— In its general aspect and coloration, this species looks like a smaller form of A. albinae. Head: integument smooth, matte; fastigium in dorsal view (Figs 21, 22), short, blunt, sides converging in an obtuse angle. Pronotum (Figs 21, 22): anterior margin of disk slightly curved or straight, posterior one projecting caudad in an obtuse angle, its apex rounded. Tegmina and wings surpassing end of abdomen in both sexes. Male abdominal terminalia (Fig. 25) with furculae absent or barely marked as undulations of margin of 10th segment, placed far apart; epiproct subquadrate with small triangular projection in posterior edge; cerci very large, strongly incurved, their apices spatulate (similar to those of A. albinae). Stridulatory mechanism with three modified pre-apical spines in the hind tibiae of males, none in the females; where the crossveins that in other species are raised, these are flat and hence without sound-producing function. Phallic complex (Fig. 30) similar in general to that of A. albinae, main differences lie in shape of epiphallus and of cingulum in dorsal view.

General coloration light apple-green (61) to straw-yellow (56). Cinnamon (39) postocular bands continued on sides of pronotum where there are, immediately below them, white bands continuous on pro- and metazona; lower margins of pronotal lobes narrowly fringed with white. All legs straw-yellow (56), including hind tibiae and tarsi. Tegmina light apple-green at sides, the discal or vannal part very pale flesh-color (5).

Affinities.— As said above, very closely related to A. albinae.

Habitat.— Usually found in rather humid places, where the vegetation of grasses and Cyperaceae is rather dense (but usually not in the places described below as the habitat of A. vitticollis). It is even abundant in hills and sierras, whenever a small spring makes a patch of denser vegetation grow surrounded by much drier grassland. But it seems tolerant of drier situations, since some specimens can also be found (but not abundantly) in drier places with less dense vegetation. It is a diurnal species but also shows some nocturnal activity.

Known distribution.— Bruner (1906:668) wrote: “This is the most abundant and, at the same time, most widely distributed species of the genus”. Working about a hundred years later, I have verified Bruner's statement. Recorded from Argentina: Provinces of Buenos Aires, La Pampa, Formosa, Chaco, Corrientes, San Juan, Tucumán, Santa Fe, Entre Rios, Mendoza, Rio Negro and Chubut. Brasil: Rio Grande do Sul. Paraguay: eastern part. Uruguay: whole country. According to what is known of its distribution in Argentina and Paraguay, it is very probable that its distribution in Brasil is much larger than recorded and includes the large area between Mato Grosso and Rio Grande do Sul (Fig. 37).

Aleuas paraguayensis n. sp. Figs 10, 11, 20, 21, 22, 24, 25C, 31, 37. Table 5

Fig. 10.

Aleuas paraguayensis n. sp. habitus. Male from Paraguay, Dept. Caaguazú, near Ihú. Length 25.8 mm. Scale line 5 mm.

Fig. 11.

Aleuas paraguayensis n. sp. habitus. Female from Paraguay, Dept. Caaguazú, near Ihú. Length 37.8 mm. Scale line 5 mm.

Etymology.— Refers to the country of its origin.

Taxonomy.— A medium-sized species (Table 5). Head rather large and globose, especially in females, its integument very smooth and shiny; fastigium very short, in superior view roundly curved in females (Fig. 22), obtusely angulate in males (Fig. 21). Pronotum (Figs 21, 22): median carina almost obsolete; integument impresso-punctate over most of the surface, except in discal part of prozona, that being covered with cicatricose depressions placed close together. Tegmina and wings reaching or surpassing end of abdomen in both sexes. Male terminalia (Fig. 25) with triangular furculae placed close together, epiproct subquadrate, with small triangular projection in middle of caudal edge; cerci conical, incurved, greatly surpassing caudal end of epiproct. Stridulatory mechanism (Fig. 35) has three pre-apical modified spines in hind tibiae of both sexes, and a long series of prominent crossveins on the tegmina. Phallic complex (Fig. 31): apical valves of archendophallus of characteristic shape, in lateral view similar to same in most species of Zygoclistron (as figured in Carbonell 1969).

Chromatic characters: the most colorful member of the genus. Antennae, lateral areas on pronotal prozona, and hind tarsi, scarlet (14). General body color sulphur yellow (57) to straw-yellow (56). Head with small black areas above antennal sockets (Fig. 20), and the following black bands: from upper parts of antennal sockets, continued narrowly on front margin of eyes; two sets of postocular bands, one from upper part of eyes to occiput, bordered on both sides with sulfur-yellow (157), other from lower part of margin of eye, fading towards middle of genae; another along basis of mandibles, the latter with black apices. Fore legs: tibiae cinnamon-rufous (40), femora with tawny (38) bands on upper surface: middle legs with femora sulphur-yellow (57), tibiae tawny (38) to scarlet (14) on upper surface: hind legs straw-yellow (56) with black bands along upper lateral carinae, this color fading to gray on upper parts of region of pinnae: hind tibiae black at bases, becoming flesh-color (5) and scarlet (14) at their tips. Tegmina sulphur-yellow (57) with pale yellow veins.

Affinities.—Not clear: epiproct of the same general shape as that of A. lineatus and A. albinae; cerci similar in form to those of A. curtipennis, A. gracilis and A. uruguayensis, but proportionally much longer.

Habitat.— The place where the known specimens of this species were found was mostly grassland, with spots of bushy vegetation.

Known distribution.— Has been found only once in the province of Caaguazú of Paraguay, a few kilometers south of the town of Ihú (Fig. 37).

Aleuas paranensis n. sp. Figs 12, 13, 20, 21, 22, 23, 26C, 32, 37. Table 6

Fig. 12.

Aleuas paranensis n. sp. habitus. Male from Argentina, Prov. Corrientes, Arroyo San Joaquin at Provincial Route 126. Length 28 mm. Scale line 5 mm.

Fig. 13.

Aleuas paranensis n. sp. habitus. Female from Argentina, Prov. Corrientes, Arroyo San Joaquin at Provincial Route 126. Length 44.5 mm. Scale line 5 mm.

Etymology.— From the name of the Paraná River, that flows in the area where the species was found.

Taxonomy.— A medium-sized species, females much larger than males (Table 6). Head: integument smooth, matte; fastigium in dorsal view triangular, its sides forming a right angle in males, a slightly acute one in females (Figs 21, 22). Pronotum: integument impressopunctate; front edge of pronotal disk slightly curved, almost straight, caudal one more definitely curved, in both sexes (Figs 21, 22) Tegmina and wings: reduced, reaching first third of abdomen in females, a little over half of it in males. Abdominal end in males (Fig. 26) with triangular furculae placed close together, epiproct triangular with slightly curved sides, cerci simple, conical, not reaching end of epiproct. Stridulatory mechanism with two modified pre-apical spines on hind tibiae, the stridulatory cross veins very prominent, covering a much larger area of the tegmina of males than in any other species. The known females are short-winged and without stridulatory crossveins. Phallic complex (Fig. 32) seems close to that of A. vitticollis.

Chromatic characters.— General coloration cinnamon (39), russet (34) in parts. Head: in front view russet (34), with black areas above antennal sockets (Fig. 20); dorsally with median longitudinal russet area that turns gradually cinnamon (39) to the sides; in lateral view, very wide postocular bands that take up most of genae, with narrow light cinnamon (39) bands above and below it. This wide russet band continues on pronotal lateral lobes, and so does the narrow light-colored band on lower edges of genae, that on inferior edge of pronotal lobes becoming almost white. The rest of the body, tegmina and most of legs are light cinnamon (39); hind tibiae and tarsi in males are red; in females almost black internally on the apical third, turning light cinnamon (39) towards femoral articulation. Inner pagina of femora light cinnamon (39) in males, mostly black (Fig. 23) in females.

Affinities.— Not clear, but probably closer to A. vitticollis than to any other species of the genus.

Habitat.— The place where the species was collected is mostly grassland.

Known distribution.— Argentina: South of the Province of Corrientes. Brasil: State of Rio Grande do Sul (Fig. 37).

Aleuas uruguayensis n. sp. Figs 14, 15, 20, 21, 22, 24, 25D, 33, 37. Table 7

Fig. 14.

Aleuas uruguayensis n. sp. Habitus. Male from Uruguay, Dept. Rivera, Lunarejo. Length 27.3 mm. Scale line 5 mm.

Fig. 15.

Aleuas uruguayensis n. sp. Habitus. Female from Uruguay, Dept. Rivera, Lunarejo. Length 44.7 mm. Scale line 5 mm.

Etymology.— Refers to the country where it was found.

Taxonomy.— A small species, particularly the males (Table 7). Head: integument smooth, matte; fastigium in dorsal view projected forwards in a slightly obtuse angle (Figs 21, 22), a distinct median carina running from fastigium to occiput. Pronotum: integument strongly rugose, a well-marked, prominent median carina on pro- and metazona; anterior margin of pronotal disk strongly curved, posterior one obtuse-angulate (Figs 21, 22). Tegmina and wings much reduced in female, reaching end of 2^nd abdominal segment; well developed and reaching end of abdomen in males. Abdominal male terminalia (Fig. 25): furculae triangular, acute, placed close together; epiproct subtriangular, with curved sides; cerci conical, tips incurved, reaching end of epiproct. Stridulatory mechanism absent. Phallic complex does not show any close relationship with any of the other species, and its cingulum (Fig. 33E) has a peculiar shape.

Chromatic characters.— The only specimens at hand are rather teneral, so their colors may not correspond to those in mature specimens. General coloration buff (24); eyes, posterior part of pronotal metazona and tegmina tawny (38); ends of hind tibiae in male reddish, in female dark brown. In both sexes, a distinct black area at limit of metathoracic epimeron-episternum, and in females the dorsal parts of metanotum and first abdominal terga, as seen between the bases of the tegmina, and also a median band on epiproct, are black.

Affinities.—Seems close to A. curtipennis, with which it shares the absence of a stridulatory mechanism.

Habitat.— Herbaceous vegetation near a small stream.

Known distribution.— Has been found only in northern Uruguay, in the east of the Department of Rivera (Fig. 37).

Aleuas vitticollis Stål 1878 (= A. brachypterus Bruner 1906) Figs 16, 17, 18, 19, 20, 21, 22, 23, 26A, 34, 37. Table 8

Fig. 16.

Aleuas vitticollis Stål 1878, habitus. Male from Argentina, Prov. Corrientes Arroyo San Joaquin at Provincial Route 126. Length 38 mm. Scale line 5 mm.

Fig. 17.

Aleuas vitticollis Stål 1878, habitus. Brachypterous female from Uruguay, Dept. Flores, Arroyo Pinto. Length 50.6 mm. Scale line 5 mm.

Fig. 18.

Aleuas vitticollis Stål 1878, habitus. Macropterous female from Uruguay, Dept. Rivera, Tranqueras. Length 52.2 mm. Scale line 5 mm.

Fig. 19.

Aleuas vitticollis Stål 1878. Variability of pattern on head and pronotum in males and females. A, female, green form, from Uruguay, Dept. Flores, Arroyo Pinto. B, female, brown form, from Argentina, Prov. Corrientes, Arroyo San Joaquin; C, male from Argentina, Chaco, Arroyo Palometa; D, male from Uruguay, Rivera, Tranqueras; E, male from Paraguay, Paraguarí, Sapucay. Scale line 5 mm.

Fig. 20.

Genus Aleuas, frontal views of head; species as indicated. Rows A, B, females; C, D, males. Scale line 5 mm.

Fig. 21.

Genus Aleuas, dorsal views of head + pronotum, males, species as indicated. Scale line 5 mm.

Fig. 22.

Genus Aleuas, dorsal views of head and pronotum, females, species as indicated. Scale line 5 mm.

Etymology.— From Latin vitta a band or ribbon and collum, the neck, referring to the dark bands on the pronotum.

Taxonomy.— A rather large species, especially the females (Table 8). Head (Figs 20, 21, 22): integument smooth, matte; fastigium in dorsal view short, rather rounded or slightly angulated forwards in a very obtuse angle. Pronotum (Figs 21, 22), integument markedly pitted throughout, in dorsal view the anterior margin very slightly curved, almost straight; posterior one curved or very obtusely angulate; most females short-winged, their tegmina reaching the hind margin of the third abdominal tergite; about 1% of them long-winged, though their tegminae do not quite reach the abdominal end, all males long-winged, tegmina not or barely reaching abdominal end. Stridulatory mechanism: only two subterminal spines on hind tibiae slightly modified; in males and long-winged females, very few (5–7) crossveins adapted for this function. Male abdominal terminalia (Fig. 26) with very acute triangular furculae, placed close together, subtriangular epiproct, cerci simple, acute, slightly outcurved at apices.

Fig. 23.

Genus Aleuas, internal view of hind legs, females, species as indicated. Scale line 5 mm.

Fig. 24.

Genus Aleuas, internal view of hind legs, females, species as indicated. Scale line 5 mm.

Fig. 25.

Genus Aleuas, end of male abdomen, dorsal and lateral views, species as indicated. Scale lines 1 mm.

Chromatic characters.— Females of this species have two color forms, one pale apple-green (61), the other pale cinnamon (39). All long-winged specimens found are of the green form. All specimens of both forms have fuscous (21) postocular bands continued on the sides of the pronotum and on the tegmina; reaching almost the end of the tegmina in short-winged specimens of the cinnamon form; marked only on their bases and gradually fading away on first half of the tegmina in short and long-winged specimens of the green form; another fuscous band runs along median longitudinal prothoracic carina and continues on dorsum of abdominal segments I and II, visible between bases of tegmina.

While in the green form genae and lateral lobes of the pronotum are apple-green, the latter narrowly fringed with white on their lower margin, in the cinnamon form, genae and lateral lobes of pronotum are marked with two or more tenuous longitudinal fuscous bands, not seen in green specimens; the lower part of the genae in these cinnamon specimens is cream-color (54); of this same color are wide bands along lower parts of lateral lobes, that continue on mesothoracic episterna. Fore and middle legs are of the prevalent body color; in the cinnamon form they are brownish, including the tarsi: hind femora are colored like the body, hind tibiae in all specimens have black bases, the rest of the tibiae and the tarsi are purple (101). No different color forms found in the males. Vertex of head mostly fuscous (21); yellow (157) bands begin on upper part of eyes and reach occiput above the fuscous postocular bands. Pronotal disk and upper (vannal) areas of tegmina light apple-green (61), rest of tegmina of a very pale hue of this color; lateral lobes of pronotum with same longitudinal fuscous bands as described for the female, a cream-color (54) wide band begins on lower parts of cephalic genae, covers the lower part of pronotal lateral lobes and continues on mesosterna and mesepimera; on pronotal lobes, above the mentioned cream-color band is a tenuous citrine (51) band, and between this and the upper piceous band the surfaces are mostly sulphur-yellow (57), with some irregular tenuous spots of citrine or cinnamon color. All legs buff-yellow (53), the fore and middle ones with indistinct cinnamon-rufous bands on upper parts of femora; hind tibiae buff-yellow (53) on external sides; interior and upper surfaces, and tarsi mostly scarlet; tibial spines white with black apices.

As indicated in the second part of this work, Stål's type of this species is a long-winged female, while in Bruner's type series according to his description, there is a short-winged one of the same species, hence the specific name (brachypterus) given to it by Bruner.

Fig. 26.

Genus Aleuas, end of male abdomen, dorsal and lateral views, species as indicated. Scale lines 1 mm.

Fig. 27.

Aleuas albinae n. sp. Phallic complex. Scale line 1 mm. A, lateral view, without epiphallus; B, cingulum, lateral; C endophallus, lateral; D, dorsal view, without epiphallus; E, cingulum, dorsal; F, endophallus, dorsal; G, epiphallus, dorsal; H, same, frontal; I, same, lateral.

Fig. 28.

Aleuas curtipennis Bruner. Phallic complex. Scale line 1 mm. Letters A to I, see caption to Fig. 27.

Fig. 29.

Aleuas gracilis Stål. Phallic complex. Scale line 1 mm. Letters A to I, see caption to Fig. 27.

Fig. 30.

Aleuas lineatus Stål. Phallic complex. Scale line 1 mm. Letters A to I, see caption to Fig. 27.

Fig. 31.

Aleuas paraguayensis n. sp. Phallic complex. Scale line 1 mm. Letters A to I, see caption to Fig. 27.

Fig. 32.

Aleuas paranensis n. sp. Phallic complex. Scale line 1 mm. Letters A to I, see caption to Fig. 27.

Known distribution.— Brasil: Mato Grosso, Mato Grosso do Sul (probably from this state south to Rio Grande do Sul). Paraguay (east). Uruguay: whole country. Argentina: from Formosa and Misiones south to Buenos Aires and La Pampa (Fig. 37).

Affinities.— Closer to A. paranensis than to any other species.

Habitat.— The habitat and ethology of this species have been described by Carbonell (1956). It has been found only in a particular habitat, formed by dense associations of tall grasses (about 1 m high) in low and humid places near water. The species was rare in collections, until the discovery that it is active only at night; in the daytime the insects are hidden at the base of the dense grass formations. At night the insects climb to the upper parts of the vegetation to feed and to mate. In the same places where it was very difficult to find one specimen in the daytime, they could be collected by the hundred at night. The grasses on which this species live are Panicum grumosum and Paspalum exaltatum. Another grass species that forms dense associations in low places is Cortaderia selloana, but A. vitticollis was not found in this habitat. Aleuas albinae shares this particular habitat with A. vitticollis, but is considerably scarcer. Both species are, in Uruguay at least, late developing ones; the first adults are usually found late in January or in the first days of February.

Fig. 33.

Aleuas uruguayensis n. sp. Phallic complex. Scale line 1 mm. Letters A to I, see caption to Fig. 27.

Fig. 34.

Aleuas vitticollis Stål. Phallic complex. Scale line 1 mm. Letters A to I, see caption to Fig. 27.

Fig. 35.

Stridulatory mechanism in Aleuas. A, Left tegmen, arrow indicates area of crossveins which are part of the stridulatory mechanism; B, region of the tegmen where these crossveins are located, arrow indicates the area; C, superior view of this area on right tegmen, arrows indicate the crossveins projecting from tegmen surface; D, apical part of right hind tibia, dorsal; E, same, lateral: arrows indicate the three tibial spines involved in stridulation. The species is A. paraguayensis. Scale lines 1 mm.

Fig. 36.

Measurements taken, as registered in Tables 1 to 8.

Fig. 37.

Genus Aleuas Stål. Geographical distribution of genus and species.

It is worth mentioning here that a species of the related genus Zygoclystron (Z. trachystictum Rehn 1905) also has nocturnal habits. It does not live on grasses but in patches of the composite plant, Vernonia nodiflora. Like A. vitticollis, it stays hidden during the day, and becomes active at night, when it climbs the Vernonia plants and can be easily found (Carbonell 1969).

Discussion on the taxonomy of the genus and its species

As already mentioned in the introduction of this work, the genus Aleuas is very closely related to Zygoclistron. The species of these genera look different, and cannot be confused. However, when trying to define their differences, one finds they are not so great as they seem at first sight; they look different mainly because of their different colors and color patterns. The most important differences are given in the following table; some are shown in Fig. 1.

The relationships among the species of Aleuas are difficult to interpret. A. albinae and A. lineatus are so much alike, that the first seems to be a larger version of the second. The most important morphological difference lies in the abdominal terminalia of the males, (Figs 25, A, B) but even these are small. On the other hand, these male terminalia are different from those of the rest of the species of the genus, and similar to those of the genus Zygoclistron. The females, except for their different sizes, are so much alike that the most visible difference lies in the colors of their hind tibiae. A. gracilis, A. paranensis and A. vitticollis show clear affinities. A. paraguayensis seems rather isolated; its male terminalia have an epiproct like that in A. albinae and A. lineatus, but the cerci are different, shaped as in the rest of the species. Its chromatic characters are also peculiar. A. curtipennis and A. uruguayensis are different from the rest of the species of the genus, and the males of both species lack the stridulatory mechanism present in all the others.