Monte Desert (Argentina): insect biodiversity and natural areas

Journal of Arid Environments (2001) 47: 77–94doi:10.1006/jare.2000.0688, available online at http://www.idealibrary.com on

Monte Desert (Argentina): insect biodiversity andnatural areas

Sergio Roig-Jun8 ent*, Gustavo Flores, Silvia Claver, Guillermo Debandi& Adriana Marvaldi

IADIZA (Instituto Argentino de Investigaciones de las Zonas Aridas),CC 507, 5500 Mendoza, Argentina

(Received 11 October 1999, accepted 19 July 2000)

Monte is a warm shrub desert of Argentina, having particular biogeographicalinterest because it lies between the Neotropical and Antarctic regions. A pre-liminary list of some insect families shows a high proportion of endemic generaand species, supporting the hypothesis that it constitutes a natural area with itsown biodiversity. The distribution of some insect species shows great concord-ance with the area occupied by the Monte Desert, indicating its limits. Howeverthe complete series of records are not enough to define the boundaries exactly.The distributional patterns of several endemic species suggest that withinMonte there are five natural areas: Northern, Central, Uspallata-Calingasta,Southern, and PenmHnsula de ValdeH s. The limits of the Northern and Uspallata-Calingasta areas are due to physiographical features (mountains) whereas theremaining areas are delimited by climatic barriers. An analysis based onphylogenetic information shows that these areas of endemism reflect dif-ferent values with respect to their biodiversity. The Northern area has thehighest values of importance and has no protected areas.

( 2001 Academic Press

Keywords: Monte Desert; insects; biodiversity; areas of endemism; conserva-tion priority

Introduction

Arid lands represent approximately 60% of the total area of Argentina, and they arelocated in three main biogeographical provinces: Patagonia, Puna, and Monte (Cabrera& Willink, 1973). Patagonia is a cold steppe of low altitude in the south. Puna is alsoa cold steppe, but located in the high northern mountains. Monte is a warm shrub desertextending between Puna and Patagonia at the east of the Andean mountains, from Salta(243 35@S) to Chubut (433 26@S) provinces (Morello, 1958).

The Monte Desert lies between the Neotropical and Antarctic regions and presentsseveral genera of shrubs (Aloysia Ortega & PalaH vy-Verdera, Capparis LinneH , CercidiumRuiz & Pavon, and Larrea Cavanilles) that are desert vicariant genera in the New World.Patagonia and Puna are evolutionarily related, whereas the Monte faunal and floralelements are more closely related to those of the Pampa and Chaco biogeographicalprovinces (Ringuelet, 1961), although some Patagonian elements also occur in theCentral and Southern part of the Monte (Roig et al., 1980).

*Corresponding author. E-mail: [email protected]

0140-1963/01/010077#18 $35.00/0 ( 2001 Academic Press

78 S. ROIG-JUN3 ENT ET AL.

Most faunal studies developed in the Monte area are based on vertebrates (Dabbene,1910; Cabrera & Yepes, 1940; Ringuelet, 1961; Fittkau, 1969; MuK ller, 1973). Worksbased on insects usually concern just a particular taxon (Porter, 1975; Teran, 1973) ora small area (Stange et al., 1976). In addition, most of them were developed in theNorthern area of the Monte, comparing this area with the Sonoran Desert (Cates& Rohades, 1977; Kingsolver et al., 1977; Schultz et al., 1977; Simpson et al., 1977;Medel & Vasquez, 1994; Medel, 1995), whereas the other areas remain scarcely known.

Our main purpose in this paper is to establish if the Monte Desert constitutes a naturalarea, comparing its species richness and endemicity with the closest biogeographicalarea (Chaco). If Monte constitutes a natural area, two aspects have to be considered: (1)definition of its boundaries, testing whether the range of insect distribution is coincidentor not with the plant-based definition of the Monte; and (2) to find out if it constitutesa homogeneous area where all species are widely distributed or if there are natural areaswithin the Monte delimited by distributional patterns of endemic species. Finally, we areinterested in evaluating the biological importance of the Monte Desert and determiningif the right degree of protection exists.

Study area: the Monte Desert

The biogeographical province of the Monte is restricted to Argentinean territory,ranging from parallel 243 to 433 South. It represents more than 38 million hectares in thewestern subandean area of the country, in the provinces of Salta, TucumaH n, Catamarca,La Rioja, San Juan, Mendoza, La Pampa, Neuquen, RmHo Negro, Buenos Aires andChubut (Fig. 1). Its landscape consists of sandy plains, plateaus and mountain bases.Annual rainfall ranges from 80 to 200 mm, and the annual mean temperature rangesfrom 13 to 15)53C.

The biogeographical province of Monte is defined as a xeric biome according to itsvegetation and physiognomy (Cabrera, 1953; Morello, 1958; Roig, 1998). The pre-dominant vegetation is a shruby steppe, with characteristic endemic flora mainly of thefamily Zygophyllaceae (Larrea, Bulnesia, and Plectocarpa Gillies). The Monte could bedefined as the Cercidium praecox Ruiz & PavoH n (Leguminosae) area of distribution aswell as the several endemic legumes. There are also edaphic communities of manyspecies such as the woods of Prosopis LinneH (Prosopis flexuosa De Candolle, P. chilensis(Moldenke) and P. alpataco (Phillipi), shrubs of Baccharis LinneH (Asteraceae) in humidplaces, Atriplex LinneH (Chenopodiaceae) in clayish soils, and Allenrolfea vaginata(Griseb) and Suaeda divaricata (Moquin) in salty soils.

Based mainly on its vertebrates, the Monte was defined as a Subandean province(Dabbene, 1910; Cabrera & Yepes, 1940; Ringuelet, 1961; Fittkau, 1969; MuK ller,1973). Cabrera & Willink (1973) gathered vegetation and fauna, establishing thebiogeographical province of the Monte, which mainly corresponds to the subandeandistrict of Cabrera & Yepes (1940). Subsequent entomological studies (Stange et al.,1976) support the concept of ‘Monte’ proposed by Cabrera & Willink (1973).

Several studies on historical biogeography provide explanations for the origin of thefauna and flora of the Monte (Morello, 1958; Ringuelet, 1961; MuK ller, 1973; Porter,1975; Solbrig et al., 1977). Its biotic elements have a great historical value because oftheir contact with Antarctic and Neotropical elements.

Monte Desert as a natural area: insect biodiversity comparison

The hypothesis that the Monte is an impoverished Chaco has been traditionally accep-ted but not rigorously tested. Stange et al. (1976) found that several genera present in theformer are also present in the latter, with fewer species in the Monte than in the

Figure 1. Distribution of Mimodromius punctaticeps (Carabidae) and Megelenophorus americanus(Tenebrionidae). Monte area is represented by dark grey, while transitional areas with Chaco,Patagonia and Espinal are represented by light grey.

INSECT BIODIVERSITY OF MONTE DESERT 79

Argentinean Chaco. To compare insect biodiversity between Chaco and Monte we used16 families belonging to different insect orders (Table 1). These families represent17,958 species recorded for 1888 genera (in 164 subfamilies) in the Neotropics. TheMonte taxa represent 3·41% (614) of this Neotropical diversity of species, 12·18% (230)of genera, and 39·02% (64) of suprageneric taxa (subfamilies and tribes). For theChaco, the 1135 species recorded represent 6·32%, the 350 genera 18·53% and the 85subfamilies and tribes 51·82% of the Neotropics. These data support the hypothesis ofStange et al. (1976) that the species richness is higher in Chaco than in Monte. Asa percentage of the Neotropical fauna, the Chaco has about twice the number of speciesof the Monte, about 6% more genera, and 12% more suprageneric groups. The reverseappears to be the case when a comparison is made using endemic taxa. We find thatMonte represents an area with higher endemicity than Chaco (Table 1). As shown inTable 1, the percentage of endemicity of the groups present in Monte is 35·01% forspecies, 10·86% for genera, and 1·56% for supraspecific taxa, whereas for Chaco it is

Table 1. Taxa present in Monte and Chaco (no. taxa present/no. endemic taxa)

Family Subfamily/Tribes Genera Species

Neotr. Chaco Monte Neotr. Chaco Monte Neotr. Chaco Monte

Gryllotalpidae 2 2/0 2/0 6 2/0 2/0 65 4/0 4/1Proscopidae 1 1/0 1/0 23 4/0 4/0 165 9/0 11/6Ommexechidae 2 1/0 2/0 12 3/0 6/3 31 7/0 8/4Tristiridae 2 0/0 1/0 17 0/0 2/1 25 0/0 2/1Romaleidae 2 1/0 1/0 100 5/0 4/0 457 11/2 4/0Acrididae 11 7/0 6/0 295 29/1 17/0 1643 56/14 22/3Miridae 8 7/0 6/0 411 83/4 56/9 1759 168/17 120/41Pachynomidae 2 1/0 0/0 2 1/0 0/0 9 1/0 0/0Cupedidae 1 0/0 1/0 1 0/0 1/0 1 0/0 1/0Ommatidae 1 1/0 1/0 1 1/0 1/0 2 2/0 2/0Karumidae 1 0/0 0/0 2 0/0 1/1 3 0/0 2/2Carabidae 50 28/1 20/0 335 96/6 54/0 4432 332/49 146/25Tenebrionidae 55 24/0 11/1 465 43/3 28/5 4331 116/46 99/53Scarabeidae 8 5/0 5/0 57 21/0 11/2 1058 80/19 44/25(Scarabeinae)Formicidae 16 7/0 5/0 119 38/0 23/0 3000 191/76 87/12Mutilidae 2 2/0 2/0 42 24/3 20/4 977 158/108 62/42

Total 164 85/1 64/1 1888 350/17 230/25 17958 1135/331 614/215

% of Neotropic 51·82 39·02 18·53 12·18 6·32 3·41% of endemism 1·17 1·56 4·85 10·86 29·16 35·01


29·16%, 4·85% and 1·17%, respectively. The percentage of endemic species on Montedepends on the group. Taxa with highest numbers of endemic species are: Nemop-teridae (Neuroptera, 100% of endemicity), Karumidae (Coleoptera, 100%), Eucraniniscarabeid beetles (83%), Mutilid wasps (67·7%), Anthidiini bees (60%, Stange et al.,1976), and Tenebrionid beetles (56·9%). Other groups have a relatively low number ofendemic species, such as carabid beetles (13·0%), Formicidae (13·79%), and Ichneu-monidae (9·8%, Porter, 1975).

Data analysed in this work show that the Monte area has lower diversity (in totalnumber of species) than the Chaco, supporting the idea of Stange et al. (1976),suggesting a trend where biodiversity decreases with aridity, while endemicity shows theopposite trend. By considering the number and percentage of endemic species andgenera (Table 1), we propose that the Monte constitutes a natural area independentfrom the Chaco. The presence of numerous species and genera exclusive to Montejustifies this area as an independent evolutive center where one-third of the biodiversityof insects assessed in the present work have originated. This hypothesis for the Montearea is also supported by several other insect families with endemic species present there,and also by several endemic genera with more than one species (Table 2).

As additional evidence, the Monte is also rich in relictual species, belonging to thefamilies Ommatidae and Cupedidae of Archostemata, an archaic group of Coleoptera,widely distributed there (Marvaldi & Roig-Jun8 ent, 1998); the Belidae, a basal family ofCurculionoidea, represented by species of Oxycoryninae associated with parasitic plantsof the family Hydnoraceae (Kuschel, 1959, 1995); the Plumariidae (Hymenotera:Chrysidoidea) with three genera in Argentina and other two in South Africa, alldistributed in arid and semi-arid areas (Roig-Alsina, 1994); and other arthropods such

Table 2. List of endemic genera of Monte

Orthoptera: Ommexechidae: 1, Neuquenina Rosas Costas; 2, Calcitrema Eades;Acrididae: 3, Papipappus Saussure;Tristiridae: 4, Pappacris Uvarov.

Hemiptera: Miridae: 5, Hyporhinocoris Reuter; 6, Cafayatina Carvalho& Carpintero; 7, Carpinteroa Carvalho; 8, Clivinemidea Carvalho& Gomes; 9, Comefulvius; 10, Ganocapsinus Carvalho; 11, DijocariaCarvalho & Carpintero; 12, Mendozaphylus Carvalho &Carpintero; 13, Neocaulotops Carvalho & Gomes; 14, SanluiziaCarvalho.

Neuroptera: Brucheiseridae: 15, Corydalus Latreille;Nemopteridae: 16, Veurice NavaH s; 17, Pastrania Orfila.

Hymenoptera: Mutillidae: 18, Scaptodactyla Burmeister;Icnhneumonidae: 19, Leptixys Townes; 20, Catadacus Townes;Vespidae: 21, Cuyodynerus Willink;Thiphiidae: 22, Calchaquila Genise;Plumariidae: 23, Maplurius Roig-Alsina.

Coleoptera: Scarabeidae: 24, Anomiopsoides* Blackwelder; 25, Eucranium* BrulleH ;26, Glyphoderus* Westwood; 27, Eudinops Burmeister; 28,Scybalophagus* Martinez; 29, Ennearabdus van Lansberge; 30,Burmeisteriellus Berg; 31, Thronistes Burmeister; 32, Colacus Ohaus;33, Pseudoliogenys Moser;

Staphylinidae: 34, Coloderella Bernhauer;Histeridae: 35, Wasmannister Bruch;Karumidae: 36, Drilocephalus Pic;Tenebrionidae: 37, Phrynocarenum Gebein; 38, Megelenophorus*Gebien; 39, Thylacoderes Solier; 40, Schizaraeus Kulzer; 41,Pectinepitragus Pic; 42, Epitragella Kulzer;Meloidae: 43, Wagneronota Dernier;Buprestidae: 44, Achardella* Obenb; 45, Calchopoecilla Thompson;Curculionidae: 46, Mendozella Hustache;Bruchidae: 47, Pectinobruchus Kingsolver;Cerambycidae: 48, Ranqueles Gounelle; 49, Paraethecerus Bruch.

*Genera with many species on Monte and with one of them extends its range out of it.


as the gondwanic Daesiidae (Solifuga) with extant species in South Africa, Spain andthe Near East, with its genera Syndaesia Maury and Valdesia Maury restricted to theMonte in Argentina (Maury, 1998).

Monte Desert as a natural area: delimitation

Entomological studies on the Monte are restricted to some systematic revisions that havegreatly enlarged the knowledge of the number and distribution of species (Willink, 1947;MonroH s, 1953; Roig-Alsina, 1989a, b; Porter, 1975; TeraH n, 1973; Stange et al., 1976).Nevertheless, none of these authors have proposed the delimitation of Monte Desertbased on distributional patterns of insects.

Identification and definition of natural areas has been classically done using en-demism, at generic or specific level. Previous authors have delimited the Monte areathrough corological or ecological methods, overlapping the distribution areas of somevertebrate (MuK ller, 1973) and arthropod species (Roig-Jun8 ent, 1994). The congruent


limits of distribution for two or more species provide an operational tool to determineareas of endemism at large scale (MuK ller, 1973; Platnick, 1991; Morrone, 1994).

Several species show a range of distribution more or less coincident with the Montebiogeographical province, as defined by its vegetation. As an example, in Fig. 1 the twospecies from all revisited with the highest number of records, a tenebrionid beetleMegelenophorus americanus (Lacordaire) and a carabid beetle Mimodromius punctaticeps(Liebke) are shown. At present no insect species have been found that show a distribu-tion strictly coincident with the Monte area as defined by vegetation. This could accountfor some endemic species of the Monte being restricted to a portion of it, such as theNorthern, Central or Southern part. On the other hand, widespread species ofMonte also have localities outside this area (Fig. 1), mainly in the transitional areasbetween the Monte and the biogeographical provinces of Chaco, Espinal or Patagonia.These are considered to be ‘mixed areas’ (Morello, 1958) with elements from Monteand other biogeographical provinces.

The overlapping method is, however, inadequate for estimating the real shape ofnatural areas, because the shape of the area depends on the number of species used.Similarly, when a large data set of distribution is available there are no strict methods todetermine their overlapping. Delimitation of the Monte area on the basis of insectdistribution patterns is also difficult because there are few species with relativelycomplete records of localities. There are important gaps even for those species witha relatively well-known distribution, mainly in the Central and the Southern parts(Fig. 1). Distributional data of species in the Monte show that those with relativelywell-known distribution (Fig. 1) do not represent a good tool when information aboutsmaller areas (Fig. 2) is needed, i.e. to define possible protected areas. Further, dataappear to be biased because most known localities are placed on or near routes, leadingto data gaps in the real distribution (Figs 2}5).

Natural areas within the Monte Desert

The wide latitudinal range of Monte Desert and the distributional patterns of itsentomofauna show the possibility of the existence of several smaller endemic areas. As

Figure 2. Distribution of Mimodromius punctaticeps and Megelenophorus americanus in centralMonte area. Routes are marked in dark grey.

Figure 3. Northern area of endemism of Monte (dark grey). Localities: 1, AndalgalaH ; 2,Chilecito; 3, Copacabana; 4, Santa MarmHa; 5, Corral Quemado; 6, Cerro Colorado; 7, Cafayate; 8,Ban8 ado; 9, Amaicha del Valle; 10, La CieH naga; 11, Colpes; 12, Schaqui; 13, Can8 armuyo; 14,BeleH n; 15, Yacochuya; 16, 20 km south of Alemania; 17, Campo El Arenal; 18, Punta Balasto; 19,Hualfin; 20, Palo Blanco; 21, Pituil; 22, Chiquimil; 22, Caspinekango; 23, Tinogasta; 24, Pilciao;25, Paso San Francisco.


was mentioned above, there are several problems of delimitated areas of endemism, andat local or regional level other problems should be taken into account to determine areasof endemism. First, there are the problems mentioned above about the lack of distribu-tional information and the bias of data localities (Figs 2–5). A second important

Figure 4. Central and Uspallata-Calingasta (dark grey) areas of endemism of Monte. Uspallata-Callingasta area localities: 1, Uspallata; 2, Picheuta; 3, Quebrada Santa Elena and CerrosColorados; 4, Sierra La Higuera; 5, Qda. Los Chacayes; 6, Tambillos; 7, Paramillos Uspallata; 8,Yalguaraz; 9, El Leocinto; 10, Calingasta; 11, Campo El Leoncito; 12, 10 km south Tocota; 13,Iglesia; 14, Las Flores; 15, Agua Negra; 16, Angualasto. Central area localities: 17, El Nihuil; 18,Agua Escondida; 19, Villavicencio; 20, Papagallos; 21, El Challao; 22, El Azufre; 23, Bermejo; 24,Zonda; 25, Palmira; 26, BorbolloH n; 27, San Rafael; 28, Guadales; 29, Telteca; 30, MascasmHn; 31,Nonogasta; 32, AsuncioH n, 33, Desaguadero; 34, south Valle FeH rtil; 35, Las Tumanas; 36, SanCarlos; 37, El Carrizal; 38, Can8 oH n del Atuel; 39, N3 acun8 aH n; 40, Jarilla; 41, El Manzano; 42,Potrerillos; 43, Cacheuta; 44, Rinconada; 45, Pie de Palo; 46, Vinchina; 47, Difunta Correa; 48,Talampaya; 49, 50 km, south Talampaya; 50, Arroyo Alumbre; 51, FortmHn MalarguK e; 52, PichiCiego; 53, Piedra Pintada; 54, Between Vinchina and Alto El JaguK el.


Figure 5. Southern area and PenmHnsula de ValdeH s, (dark grey) areas of endemism of Monte.PenmHnsula de ValdeH s localities: 1, PenmHnsula ValdeH s; 2, Punta Delgada; 3, Puerto PiraHmides; 4,Punta Norte; 5, Puerto Madryn; 6, Trelew. Southern area localities: 7, Dique Ameghino; 8, Piedradel Aguila; 9, Aguada Cecilio; 10, General Conesa; 11, Casa de Piedra; 12, Ranquil Norte; 13,Cinco Saltos; 14, RmHo Salado; 15, RmHo Agrio; 16, San Antonio Oeste; 17, Bajo el Gualicho; 18,Carmen de Patagones; 19, Villa Regina; 20, Los Alamos; 21, 20 km W Agua Escondida; 22,FortmHn MalarguK e.


difficulty concerns the congruent distributional limits of species, since the distribu-tions of members of a diverse assemblage are usually non-sympatric. The strict sym-patry of endemic species is scarce at regional level of the Monte area. Harold & Mooi(1994) suggested that assemblages lacking distributional information should be

Table 3. Endemic species of Carabidae, Curculionidae, Scarabeidae, andTenebrionidae used to establish the natural areas of Monte

Area Species

Northern Carabidae: Mimodromius proseni.Curculionidae: Enoplopactus catamarcensis: E. hylula.Scarabeidae: Anomiopsoides aberrans; A. catamarcae:

A. heteroclyta; A. pereirae; Glyphoderus monticola.Tenebrionidae: Discopleurus argentinensis; Ecnomoderes

barbatus; Entomoderes pustulosus; E. infernalis; E. subauratus;Epipedonota intercostata; E. plicatissima; Nycteliavageimpressa; Platyholmus catamarcanus; Psectrascelisinfravestita; P. linearis; Schizaraeus acuticosta.

Central Curculionidae: Enoplopactus lizeri; E. sanjuaninus.Scarabeidae: Glyphoderus sterquilinus.Tenebrionidae: Calymmophorus cucullatus; Emmallodera

perlifera; Entomoderes satanicus; Epipedonota laevisulcata;Nyctelia alutacea; N. explanata; N. subsulcata; Pectinepitraguspubescens; Pimelosomus willinki; Platyholmus diversecostatus;Psectrascelis nitida; P. vestita; Scotobius wittmeri; Thylacoderesseminulum, T. sphaericus.

Calingasta- Carabidae: Barypus mendozensis.Uspallata Curculionidae: Cylydrorhinus oblongus; Mendozella curvispinis.

Tenebrionidae: Calymnophorus uspallatensis; Epipedonota senex;Nyctelia paracepunctata; N. plicatipennis; Physogasterlongipilis; P. chechoi; P. nov. sp.; Platyholmus uspallatensis,P. nov. sp.; Psectrascelis deplanata; P, mamillonea;Scelidospecta lobata; S. granulosa; S. roigi.

Southern Carabidae: Barypus dentipennis; B. schajovskoyi; Cnemalobusneuquensis; Mimodromius fleissi; M. nigroeburneus;M. phaeoxanthus; M. straneoi.

Tenebrionidae: Emmallodera crenatocostata; E. hirtipes;Epipedonota reticulata; Leptynoderes fuscula; N. dorsata;N. rugosa; Patagonogenius collaris; Scotobius casicus.

Scarabeidae: Eucranium dentifrons.PenmHnsula Carabidae: Cnemalobus litoralis

de ValdeH s Tenebrionidae: Nyctelia circumundata; Psectrascelis sulcicollis.


considered as members of the same areas of endemism. The researcher may thenintroduce information independently of biotic distribution, i.e. physiographical features.These authors argue that such designed areas are hypotheses which further data couldreject or support.

There are several endemic assemblages of species (Table 3) that allow the identifica-tion of five natural areas within the Monte Desert. Data from physiography andecological restrictions provide the hypothetical limits of these areas. In this analysis weuse species of four families of Coleoptera (Carabidae, Curculionidae, Scarabeidae, andTenebrionidae; Table 3) whose distributions are well-known because they are thegroups best represented in entomological collections. Based on these species the fiverecognized areas are:

1. Northern area (Fig. 3). This is a long surface from Salta to Northern La Riojaprovinces. It is formed by three longitudinal valleys (CalchaqumH , Quilmes and Santa


MarmHa), at the oriental boundary of the Puna (Morello, 1958), reaching ‘Campo ElArenal’ in Catamarca. This area also includes the ‘BolsoH n de Pipanaco’, Tinogastain Catamarca and Famatina in La Rioja. The Northern area is nearly completelylimited by mountain chains until the 28340@, and partially separated from theCentral part of the Monte by the mountain chains of Sierra de Velazco andFamatina in La Rioja, where the Monte area is very narrow. This Northern areashares several insect taxa and floristic elements with the biogeographical provinceof Chaco, that are not found in other parts of Monte. Several endemic generabelong to this area, mainly in the valleys of Catamarca, TucumaH n and Salta. Itsclimate is subtropical (Morello, 1958), with a mean annual temperature of 153C.

2. Central area (Fig. 4). This ranges from the province of La Rioja to SouthernMendoza. This area of the Monte constitutes a wide strip of land (almost 200 kmfrom east to west), where mountain chains are insular such as the Precordillera andPie de Palo. It contacts widely with the Chacoan biogeographical province in thenorth-east and with the Espinal in the east. Its climate is subtropical, warmtemperate. This area has several elements that belong to the Neotropical andPatagonian biotas. The southern part of this area is connected with the Southernarea of the Monte by a long fringe of about 300 km of longitude, without a clearbiogeographical barrier, and with elements from both the Southern and Centralareas of the Monte.

3. Uspallata-Calingasta valley (Fig. 4). This is a small area of endemism within theMonte that ranges from northern San Juan province, reaching to north of Men-doza. It consists of two high altitude longitudinal valleys, that run 300 km fromnorth to south from 1900 to 2400 m of altitude. It is the most arid region withscarce vegetation, and is limited to the west by the Andean Cordillera(5000–6000 m high) and to the east by the Precordillera (3000 m high).

4. Southern area (Fig. 5). This streches from south of Mendoza to east centralChubut, and constitutes the greatest area of endemism within the Monte. Itrepresents a wide area that ranges from the Andes foothills to the Atlantic coast andconsists of homogeneous sandy plains. Roig (1998) has recently analysed thenorthern part of the Patagonia geographical region, constituted by the Monte,showing that it is formed by steppes with nanophanerophytes in a semi-aridclimate. It presents a wide ecotonal fringe at the west and south in Patagonia andnorth with the Espinal. This area is rich in endemic species of several Patagoniangenera. It is the coldest area of the Monte, with Mediterranean climate, and meanannual temperatures ranging from 113 to 133C.

5. PenmHnsula de ValdeH s (Fig. 5). This is the smallest area of endemism of the Monte,confined to the PenmHnsula de ValdeH s and to the littoral Monte of Chubut province.It is coincident with the Shrub Atlantic district of the Monte (Roig, 1998). Thewestern limit is constituted by precipitation, a 160 mm isohyet, reaching 250 mmin its more humid places. It is formed by steppes with nanophanerophytes but witha maritime climate.

Priorities for conservation: an example with cladistic measures

The distributional information developed below considerably affects the conserva-tion decisions, because maps of species distribution are useful at different levels: (1)at the species level, they help to identify which species are rare or in danger of extinction,giving a preliminary idea about ecological restrictions; and (2) at the geographical level,they allow definition and delimitation of biogeographical areas to explain the distributionof the species and to evaluate their biological importance.

The 16 protected areas within the Monte represent only 1·52% of the total surface(Roig-Jun8 ent & Claver, 1999). These protected areas are not sufficient for


biodiversity conservation and, because of their distribution, the reserves function asislands within an increasingly degraded landscape. The criteria applied to create theseprotected areas tended in most cases towards preservation of the landscape or of thenatural forests. Almost nothing is known about the entomofauna and the speciesrepresented in these protected areas (Roig-Jun8 ent & Claver, 1999).

Owing to the increasing human activities it is urgently necessary to estimate theproportion of protected species and to know which ones should be protected. Asconservation of all areas and all species is not possible, efficient methodological toolsshould be used for priority decisions, to ensure as much conservation of the biodiversityas possible (Morrone & Crisci, 1992).

Identification of insect conservation areas in the Monte by means of traditionalpriorization criteria, such as species richness (Williams et al., 1991) or endemism (Kerr,1997) is difficult. This is mainly because our knowledge of species richness anddistribution of insects in the Monte is still very scarce, even for the currently protectedareas.

Several methods proposed during the last decade incorporate phylogenetic informa-tion for conservation priority (Vane-Wright et al., 1991; Humphries et al., 1991;Williams et al., 1991). The method of Vane-Wright et al. (1991), reviewed in Morrone& Crisci (1992), appears to us to be a practical tool to set priority areas for biodiversityconservation in the Monte. It has also been applied by Morrone et al. (1996) to proposeconservation priorities in temperate areas of the world. Vane-Wright et al. (1991)proposed an index taking into account the number of clades in the cladogram whereeach species is included. These values of information (I) reflect the proportion withwhich each species contributes to the groups; the total value is divided by the one of eachspecies obtaining the basal weights (Q). Then these values can be standardized bydividing each of them by the lowest value of Q, obtaining the taxonomic weights (W),which can also be expressed as percentages (P). Measures of species inhabiting a par-ticular area can be added up to give a value to that area.

In the present paper we have applied this cladistic measure (Figs 6}11) to proposepriorities of biodiversity conservation in the Monte areas of endemism, defined above,

Figure 6. Cladogram and values for species according to phylogenetic information of genusEntomoderes (Coleoptera: Tenebrionidae). Areas are coded as: C: Chaco; CM: Central Monte;NM: Northern Monte; SM: Southern Monte; and ** others areas not considered in this work.References for values (after Vane-Wright et al., 1991): I, number of groups to which each taxonbelongs; Q, quotient of the total information for the whole group; W, weight for each taxon;P, percentage.

Figure 7. Cladogram and values for species according to phylogenetic information of genusEnoplopactus (Coleoptera: Curculionidae). Legend as Figure 6.

Figure 8. Cladogram and values for species according to phylogenetic information of genusspecies of genus Bulnesia (Zygophyllaceae). Legend as Figure 6.

Figure 9. Cladogram and values for species according to phylogenetic information of species ofgenus Cnemalobus (Coleoptera: Carabidae). Legend as Figure 6.


Figure 10. Cladogram and values for species according to phylogenetic information of species ofgenus Pompilocalus (Hymenoptera: Pompilidae). Legend as Figure 6.

Table 4. Percentages of importgance of the areas based on six genera used in thisanalysis

Northern Central Southern Uspallata PenmHnsula OthersTaxa Chaco Monte Monte Monte Calingasta Valdes areas

Entomoderes 12·9 42·6 12·4 4·1 1·5 — 26·0Enoplopactus 32·5 47·5 20·0 — — — —Bulnesia 36·1 31·4 3·8 — — — 32·2Cnemalobus 3·0 36·3 3·0 9·0 — 6·0 42·2Pompilocalus 9·6 6·5 9·8 6·7 3·3 4·9 50·0Doeringiella 33·6 10·3 8·2 16·5 5·2 1·4 21·0Total 21·2 29·1 9·5 6·0 1·6 2·0 28·6

The column totals correspond to the mean for each column.


and in the Chacoan region. We have used cladistic information about six genera ofinsects and plants: Entomoderes Solier (Tenebrionidae; Flores & Roig-Jun8 ent, 1997;Fig. 6); Enoplopactus Heller (Curculionidae; Lanteri, 1990; Fig. 7), Bulnesia Gay(Zygophyllaceae; Crisci et al., 1979; Fig. 8), Cnemalobus GueH rin-MeH neH ville (Carabidae;Roig-Jun8 ent & Flores, 1995; Fig. 9), Pompilocalus Roig-Alsina (Pompilidae; Roig-Alsina, 1989a; Fig. 10), and Doeringiella Holmberg (Anthophoridae; Roig-Alsina,1989b, Fig.11). Figures 6}11 show cladograms of these genera and the distribution ofeach species with the values, following Vane-Wright et al. (1991). By adding the valuesfor all the species inhabiting the same area, we assigned a value to that particular area

Figure 11. Cladogram and values for species according to phylogenetic information of species ofgenus Doeringiella (Hymenoptera: Anthophoridae). Legend as Figure 6.


(Table 4). The value of species occurring in more than one area was divided by thenumber of areas where the species occurs, and this resulting value was added to each ofthe areas where it occurs. According to these results (Table 4), the areas are ranked forpriority in conservation as follows: (1) Northern Monte, 29·1% importance; (2) Chaco,21·2%; (3) Central Monte, 9·5%; (4) Southern Monte, 6·0%; PenmHnsula de ValdeH s, 2·0%;and Uspallata-Calingasta valley, 1·6%.

All the reserves currently placed in the biogeographic province of the Monte arewithin the Central and Southern Monte areas, the Northern area being without anyprotected surface (Roig-Jun8 ent & Claver, 1999). Paradoxically, the results of the presentpaper show the Northern area of the Monte as the most important for conservation.


Therefore, we emphasize the necessity for setting reserves in the northern Monte area toprotect several endemic species, allowing maintenance of as much as possible of thebiodiversity.

Conclusions

The results of the present study lead to the conclusion that the alfa diversity of the Monteis lower than the alfa diversity of the Chaco, but that the Monte area has a higherproportion of endemic taxa than Chaco. Consequently, although the traditional hypoth-esis that Monte is an impoverished Chaco may be true, the high proportion of speciesthat are exclusive to Monte suggests an evolutionary history independent from Chaco.We conclude that the Monte constitutes a natural area.

There are some species that could be used to delimit the Monte area, but the availableinformation on distributional patterns of these Monte insects is still very incomplete,showing a serious lack of information. Based exclusively in four rather well-knownColeoptera families, five areas of endemism are proposed for the Monte. These areas aredistributed latitudinally from the north to the south, the Central and Southern areasbeing larger than the Northern area, Uspallata-Calingasta valley, and PenmHnsula deValdes. The lack of information, together with the increasing human activity, emphasizethe necessity for survey research in conservation. The conservation value for differ-ent areas of endemism herein proposed have been evaluated, with the Northern area ofMonte deemed to present the highest priority for conservation. Paradoxically, noprotected area is currently located within this area, and this highlights the need to setconservation areas in the Northern Monte (i.e. in Catamarca, TucumaH n and Saltaprovinces).

The present knowledge of the insects of the Monte is still too scarce to allow completecomparative studies, for example between Monte and Chaco or Patagonia. A moreexhaustive study of the Monte biodiversity will require collaboration between severalresearch teams and we hope this work represents a first step towards this goal.

The field work of this study was supported by a grant of Consejo Nacional de InvestivacionesCientmHficas y TeH cnicas, Argentina (CONICET, PIP 4678). The National Geographic Society alsosupported part of the field work in Patagonian areas. We thank Henry Noel Le HoueH rou, CharlesA. Triplehorn, Jorge Crisci, Juan JoseH Morrone-Luppi, and Esperanza Cerden8 o for their com-ments on the manuscript. MarmHa Elena Soler helped with the English.

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Monte Desert (Argentina): insect biodiversity and natural areas

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