Journal of Arid Environments (2001) 47: 77–94
doi:10.1006/jare.2000.0688, available online at http://www.idealibrary.com on
Monte Desert (Argentina): insect biodiversity and
natural areas
Sergio Roig-Jun 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 biogeographical
interest because it lies between the Neotropical and Antarctic regions. A preliminary list of some insect families shows a high proportion of endemic genera
and species, supporting the hypothesis that it constitutes a natural area with its
own biodiversity. The distribution of some insect species shows great concordance with the area occupied by the Monte Desert, indicating its limits. However
the complete series of records are not enough to define the boundaries exactly.
The distributional patterns of several endemic species suggest that within
Monte there are five natural areas: Northern, Central, Uspallata-Calingasta,
Southern, and PenmH nsula de ValdeH s. The limits of the Northern and UspallataCalingasta areas are due to physiographical features (mountains) whereas the
remaining areas are delimited by climatic barriers. An analysis based on
phylogenetic information shows that these areas of endemism reflect different values with respect to their biodiversity. The Northern area has the
highest values of importance and has no protected areas.
2001 Academic Press
Keywords: Monte Desert; insects; biodiversity; areas of endemism; conservation priority
Introduction
Arid lands represent approximately 60% of the total area of Argentina, and they are
located 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 also
a cold steppe, but located in the high northern mountains. Monte is a warm shrub desert
extending between Puna and Patagonia at the east of the Andean mountains, from Salta
(243 35S) to Chubut (433 26S) provinces (Morello, 1958).
The Monte Desert lies between the Neotropical and Antarctic regions and presents
several genera of shrubs (Aloysia Ortega & PalaH vy-Verdéra, Capparis LinneH , Cercidium
Ruiz & Pavon, and Larrea Cavanilles) that are desert vicariant genera in the New World.
Patagonia and Puna are evolutionarily related, whereas the Monte faunal and floral
elements are more closely related to those of the Pampa and Chaco biogeographical
provinces (Ringuelet, 1961), although some Patagonian elements also occur in the
Central 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-JUN 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). Works
based on insects usually concern just a particular taxon (Porter, 1975; Terán, 1973) or
a small area (Stange et al., 1976). In addition, most of them were developed in the
Northern 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 natural
area, comparing its species richness and endemicity with the closest biogeographical
area (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 coincident
or not with the plant-based definition of the Monte; and (2) to find out if it constitutes
a homogeneous area where all species are widely distributed or if there are natural areas
within the Monte delimited by distributional patterns of endemic species. Finally, we are
interested in evaluating the biological importance of the Monte Desert and determining
if 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 the
western subandean area of the country, in the provinces of Salta, TucumaH n, Catamarca,
La Rioja, San Juan, Mendoza, La Pampa, Neuquén, RmH o Negro, Buenos Aires and
Chubut (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 ranges
from 13 to 15)53C.
The biogeographical province of Monte is defined as a xeric biome according to its
vegetation and physiognomy (Cabrera, 1953; Morello, 1958; Roig, 1998). The predominant vegetation is a shruby steppe, with characteristic endemic flora mainly of the
family Zygophyllaceae (Larrea, Bulnesia, and Plectocarpa Gillies). The Monte could be
defined as the Cercidium praecox Ruiz & PavoH n (Leguminosae) area of distribution as
well as the several endemic legumes. There are also edaphic communities of many
species such as the woods of Prosopis LinneH (Prosopis flexuosa De Candolle, P. chilensis
(Moldenke) and P. alpataco (Phillipi), shrubs of Baccharis LinneH (Asteraceae) in humid
places, 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 the
biogeographical province of the Monte, which mainly corresponds to the subandean
district 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 the
fauna 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 of
their 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 accepted but not rigorously tested. Stange et al. (1976) found that several genera present in the
former are also present in the latter, with fewer species in the Monte than in the
INSECT BIODIVERSITY OF MONTE DESERT
79
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.
Argentinean Chaco. To compare insect biodiversity between Chaco and Monte we used
16 families belonging to different insect orders (Table 1). These families represent
17,958 species recorded for 1888 genera (in 164 subfamilies) in the Neotropics. The
Monte 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 the
Chaco, the 1135 species recorded represent 6·32%, the 350 genera 18·53% and the 85
subfamilies and tribes 51·82% of the Neotropics. These data support the hypothesis of
Stange et al. (1976) that the species richness is higher in Chaco than in Monte. As
a percentage of the Neotropical fauna, the Chaco has about twice the number of species
of the Monte, about 6% more genera, and 12% more suprageneric groups. The reverse
appears to be the case when a comparison is made using endemic taxa. We find that
Monte represents an area with higher endemicity than Chaco (Table 1). As shown in
Table 1, the percentage of endemicity of the groups present in Monte is 35·01% for
species, 10·86% for genera, and 1·56% for supraspecific taxa, whereas for Chaco it is
S. ROIG-JUN ENT ET AL.
80
Table 1. Taxa present in Monte and Chaco (no. taxa present/no. endemic taxa)
Family
Subfamily/Tribes
Neotr. Chaco
Gryllotalpidae
Proscopidae
Ommexechidae
Tristiridae
Romaleidae
Acrididae
Miridae
Pachynomidae
Cupedidae
Ommatidae
Karumidae
Carabidae
Tenebrionidae
Scarabeidae
(Scarabeinae)
Formicidae
Mutilidae
Total
% of Neotropic
% of endemism
Genera
Monte Neotr. Chaco
Species
Monte Neotr.
Chaco
Monte
2
1
2
2
2
11
8
2
1
1
1
50
55
8
2/0
1/0
1/0
0/0
1/0
7/0
7/0
1/0
0/0
1/0
0/0
28/1
24/0
5/0
2/0
1/0
2/0
1/0
1/0
6/0
6/0
0/0
1/0
1/0
0/0
20/0
11/1
5/0
6
23
12
17
100
295
411
2
1
1
2
335
465
57
2/0
4/0
3/0
0/0
5/0
29/1
83/4
1/0
0/0
1/0
0/0
96/6
43/3
21/0
2/0
4/0
6/3
2/1
4/0
17/0
56/9
0/0
1/0
1/0
1/1
54/0
28/5
11/2
65
165
31
25
457
1643
1759
9
1
2
3
4432
4331
1058
4/0
4/1
9/0
11/6
7/0
8/4
0/0
2/1
11/2
4/0
56/14
22/3
168/17 120/41
1/0
0/0
0/0
1/0
2/0
2/0
0/0
2/2
332/49 146/25
116/46
99/53
80/19
44/25
16
2
7/0
2/0
5/0
2/0
119
42
38/0
24/3
23/0
20/4
3000
977
191/76
158/108
164
85/1
64/1
1888
350/17
51·82
1·17
39·02
1·56
18·53
4·85
87/12
62/42
230/25 17958 1135/331 614/215
12·18
10·86
6·32
3·41
29·16 35·01
29·16%, 4·85% and 1·17%, respectively. The percentage of endemic species on Monte
depends on the group. Taxa with highest numbers of endemic species are: Nemopteridae (Neuroptera, 100% of endemicity), Karumidae (Coleoptera, 100%), Eucranini
scarabeid 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 of
endemic species, such as carabid beetles (13·0%), Formicidae (13·79%), and Ichneumonidae (9·8%, Porter, 1975).
Data analysed in this work show that the Monte area has lower diversity (in total
number of species) than the Chaco, supporting the idea of Stange et al. (1976),
suggesting a trend where biodiversity decreases with aridity, while endemicity shows the
opposite trend. By considering the number and percentage of endemic species and
genera (Table 1), we propose that the Monte constitutes a natural area independent
from the Chaco. The presence of numerous species and genera exclusive to Monte
justifies this area as an independent evolutive center where one-third of the biodiversity
of insects assessed in the present work have originated. This hypothesis for the Monte
area 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 the
families Ommatidae and Cupedidae of Archostemata, an archaic group of Coleoptera,
widely distributed there (Marvaldi & Roig-Jun ent, 1998); the Belidae, a basal family of
Curculionoidea, represented by species of Oxycoryninae associated with parasitic plants
of the family Hydnoraceae (Kuschel, 1959, 1995); the Plumariidae (Hymenotera:
Chrysidoidea) with three genera in Argentina and other two in South Africa, all
distributed in arid and semi-arid areas (Roig-Alsina, 1994); and other arthropods such
INSECT BIODIVERSITY OF MONTE DESERT
81
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, Dijocaria
Carvalho & Carpintero; 12, Mendozaphylus Carvalho &
Carpintero; 13, Neocaulotops Carvalho & Gomes; 14, Sanluizia
Carvalho.
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 and
the Near East, with its genera Syndaesia Maury and Valdesia Maury restricted to the
Monte in Argentina (Maury, 1998).
Monte Desert as a natural area: delimitation
Entomological studies on the Monte are restricted to some systematic revisions that have
greatly 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 Desert
based on distributional patterns of insects.
Identification and definition of natural areas has been classically done using endemism, at generic or specific level. Previous authors have delimited the Monte area
through corological or ecological methods, overlapping the distribution areas of some
vertebrate (MuK ller, 1973) and arthropod species (Roig-Jun ent, 1994). The congruent
82
S. ROIG-JUN ENT ET AL.
limits of distribution for two or more species provide an operational tool to determine
areas 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 Monte
biogeographical province, as defined by its vegetation. As an example, in Fig. 1 the two
species from all revisited with the highest number of records, a tenebrionid beetle
Megelenophorus americanus (Lacordaire) and a carabid beetle Mimodromius punctaticeps
(Liebke) are shown. At present no insect species have been found that show a distribution strictly coincident with the Monte area as defined by vegetation. This could account
for some endemic species of the Monte being restricted to a portion of it, such as the
Northern, Central or Southern part. On the other hand, widespread species of
Monte also have localities outside this area (Fig. 1), mainly in the transitional areas
between the Monte and the biogeographical provinces of Chaco, Espinal or Patagonia.
These are considered to be ‘mixed areas’ (Morello, 1958) with elements from Monte
and other biogeographical provinces.
The overlapping method is, however, inadequate for estimating the real shape of
natural 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 to
determine their overlapping. Delimitation of the Monte area on the basis of insect
distribution patterns is also difficult because there are few species with relatively
complete records of localities. There are important gaps even for those species with
a 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 relatively
well-known distribution (Fig. 1) do not represent a good tool when information about
smaller areas (Fig. 2) is needed, i.e. to define possible protected areas. Further, data
appear to be biased because most known localities are placed on or near routes, leading
to 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 its
entomofauna show the possibility of the existence of several smaller endemic areas. As
Figure 2. Distribution of Mimodromius punctaticeps and Megelenophorus americanus in central
Monte area. Routes are marked in dark grey.
INSECT BIODIVERSITY OF MONTE DESERT
83
Figure 3. Northern area of endemism of Monte (dark grey). Localities: 1, AndalgalaH ; 2,
Chilecito; 3, Copacabana; 4, Santa MarmH a; 5, Corral Quemado; 6, Cerro Colorado; 7, Cafayate; 8,
Ban ado; 9, Amaicha del Valle; 10, La CieH naga; 11, Colpes; 12, Schaqui; 13, Can 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, and
at local or regional level other problems should be taken into account to determine areas
of endemism. First, there are the problems mentioned above about the lack of distributional information and the bias of data localities (Figs 2–5). A second important
84
S. ROIG-JUN ENT ET AL.
Figure 4. Central and Uspallata-Calingasta (dark grey) areas of endemism of Monte. UspallataCallingasta area localities: 1, Uspallata; 2, Picheuta; 3, Quebrada Santa Elena and Cerros
Colorados; 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, MascasmH n; 31,
Nonogasta; 32, AsuncioH n, 33, Desaguadero; 34, south Valle FeH rtil; 35, Las Tumanas; 36, San
Carlos; 37, El Carrizal; 38, Can oH n del Atuel; 39, N acun 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, FortmH n MalarguK e; 52, Pichi
Ciego; 53, Piedra Pintada; 54, Between Vinchina and Alto El JaguK el.
INSECT BIODIVERSITY OF MONTE DESERT
85
Figure 5. Southern area and PenmH nsula de ValdeH s, (dark grey) areas of endemism of Monte.
PenmH nsula de ValdeH s localities: 1, PenmH nsula ValdeH s; 2, Punta Delgada; 3, Puerto PiraH mides; 4,
Punta Norte; 5, Puerto Madryn; 6, Trelew. Southern area localities: 7, Dique Ameghino; 8, Piedra
del Aguila; 9, Aguada Cecilio; 10, General Conesa; 11, Casa de Piedra; 12, Ranquil Norte; 13,
Cinco Saltos; 14, RmH o Salado; 15, RmH o 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,
FortmH n MalarguK e.
difficulty concerns the congruent distributional limits of species, since the distributions of members of a diverse assemblage are usually non-sympatric. The strict sympatry of endemic species is scarce at regional level of the Monte area. Harold & Mooi
(1994) suggested that assemblages lacking distributional information should be
S. ROIG-JUN ENT ET AL.
86
Table 3. Endemic species of Carabidae, Curculionidae, Scarabeidae, and
Tenebrionidae used to establish the natural areas of Monte
Area
Northern
Central
CalingastaUspallata
Southern
PenmH nsula
de ValdeH s
Species
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; Nyctelia
vageimpressa; Platyholmus catamarcanus; Psectrascelis
infravestita; P. linearis; Schizaraeus acuticosta.
Curculionidae: Enoplopactus lizeri; E. sanjuaninus.
Scarabeidae: Glyphoderus sterquilinus.
Tenebrionidae: Calymmophorus cucullatus; Emmallodera
perlifera; Entomoderes satanicus; Epipedonota laevisulcata;
Nyctelia alutacea; N. explanata; N. subsulcata; Pectinepitragus
pubescens; Pimelosomus willinki; Platyholmus diversecostatus;
Psectrascelis nitida; P. vestita; Scotobius wittmeri; Thylacoderes
seminulum, T. sphaericus.
Carabidae: Barypus mendozensis.
Curculionidae: Cylydrorhinus oblongus; Mendozella curvispinis.
Tenebrionidae: Calymnophorus uspallatensis; Epipedonota senex;
Nyctelia paracepunctata; N. plicatipennis; Physogaster
longipilis; P. chechoi; P. nov. sp.; Platyholmus uspallatensis,
P. nov. sp.; Psectrascelis deplanata; P, mamillonea;
Scelidospecta lobata; S. granulosa; S. roigi.
Carabidae: Barypus dentipennis; B. schajovskoyi; Cnemalobus
neuquensis; 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.
Carabidae: Cnemalobus litoralis
Tenebrionidae: Nyctelia circumundata; Psectrascelis sulcicollis.
considered as members of the same areas of endemism. The researcher may then
introduce information independently of biotic distribution, i.e. physiographical features.
These authors argue that such designed areas are hypotheses which further data could
reject or support.
There are several endemic assemblages of species (Table 3) that allow the identification of five natural areas within the Monte Desert. Data from physiography and
ecological restrictions provide the hypothetical limits of these areas. In this analysis we
use species of four families of Coleoptera (Carabidae, Curculionidae, Scarabeidae, and
Tenebrionidae; Table 3) whose distributions are well-known because they are the
groups best represented in entomological collections. Based on these species the five
recognized areas are:
1. Northern area (Fig. 3). This is a long surface from Salta to Northern La Rioja
provinces. It is formed by three longitudinal valleys (CalchaqumH , Quilmes and Santa
INSECT BIODIVERSITY OF MONTE DESERT
2.
3.
4.
5.
87
MarmH a), at the oriental boundary of the Puna (Morello, 1958), reaching ‘Campo El
Arenal’ in Catamarca. This area also includes the ‘BolsoH n de Pipanaco’, Tinogasta
in Catamarca and Famatina in La Rioja. The Northern area is nearly completely
limited by mountain chains until the 28340, and partially separated from the
Central part of the Monte by the mountain chains of Sierra de Velazco and
Famatina in La Rioja, where the Monte area is very narrow. This Northern area
shares several insect taxa and floristic elements with the biogeographical province
of Chaco, that are not found in other parts of Monte. Several endemic genera
belong to this area, mainly in the valleys of Catamarca, TucumaH n and Salta. Its
climate is subtropical (Morello, 1958), with a mean annual temperature of 153C.
Central area (Fig. 4). This ranges from the province of La Rioja to Southern
Mendoza. This area of the Monte constitutes a wide strip of land (almost 200 km
from east to west), where mountain chains are insular such as the Precordillera and
Pie de Palo. It contacts widely with the Chacoan biogeographical province in the
north-east and with the Espinal in the east. Its climate is subtropical, warm
temperate. This area has several elements that belong to the Neotropical and
Patagonian biotas. The southern part of this area is connected with the Southern
area of the Monte by a long fringe of about 300 km of longitude, without a clear
biogeographical barrier, and with elements from both the Southern and Central
areas of the Monte.
Uspallata-Calingasta valley (Fig. 4). This is a small area of endemism within the
Monte that ranges from northern San Juan province, reaching to north of Mendoza. It consists of two high altitude longitudinal valleys, that run 300 km from
north to south from 1900 to 2400 m of altitude. It is the most arid region with
scarce 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).
Southern area (Fig. 5). This streches from south of Mendoza to east central
Chubut, and constitutes the greatest area of endemism within the Monte. It
represents a wide area that ranges from the Andes foothills to the Atlantic coast and
consists of homogeneous sandy plains. Roig (1998) has recently analysed the
northern part of the Patagonia geographical region, constituted by the Monte,
showing that it is formed by steppes with nanophanerophytes in a semi-arid
climate. It presents a wide ecotonal fringe at the west and south in Patagonia and
north with the Espinal. This area is rich in endemic species of several Patagonian
genera. It is the coldest area of the Monte, with Mediterranean climate, and mean
annual temperatures ranging from 113 to 133C.
PenmH nsula de ValdeH s (Fig. 5). This is the smallest area of endemism of the Monte,
confined to the PenmH nsula de ValdeH s and to the littoral Monte of Chubut province.
It is coincident with the Shrub Atlantic district of the Monte (Roig, 1998). The
western limit is constituted by precipitation, a 160 mm isohyet, reaching 250 mm
in its more humid places. It is formed by steppes with nanophanerophytes but with
a maritime climate.
Priorities for conservation: an example with cladistic measures
The distributional information developed below considerably affects the conservation 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 distribution
of the species and to evaluate their biological importance.
The 16 protected areas within the Monte represent only 1·52% of the total surface
(Roig-Jun ent & Claver, 1999). These protected areas are not sufficient for
88
S. ROIG-JUN ENT ET AL.
biodiversity conservation and, because of their distribution, the reserves function as
islands within an increasingly degraded landscape. The criteria applied to create these
protected areas tended in most cases towards preservation of the landscape or of the
natural forests. Almost nothing is known about the entomofauna and the species
represented in these protected areas (Roig-Jun ent & Claver, 1999).
Owing to the increasing human activities it is urgently necessary to estimate the
proportion of protected species and to know which ones should be protected. As
conservation of all areas and all species is not possible, efficient methodological tools
should be used for priority decisions, to ensure as much conservation of the biodiversity
as possible (Morrone & Crisci, 1992).
Identification of insect conservation areas in the Monte by means of traditional
priorization criteria, such as species richness (Williams et al., 1991) or endemism (Kerr,
1997) is difficult. This is mainly because our knowledge of species richness and
distribution of insects in the Monte is still very scarce, even for the currently protected
areas.
Several methods proposed during the last decade incorporate phylogenetic information 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 biodiversity
conservation in the Monte. It has also been applied by Morrone et al. (1996) to propose
conservation 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 where
each species is included. These values of information (I) reflect the proportion with
which each species contributes to the groups; the total value is divided by the one of each
species obtaining the basal weights (Q). Then these values can be standardized by
dividing 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 particular 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 propose
priorities of biodiversity conservation in the Monte areas of endemism, defined above,
Figure 6. Cladogram and values for species according to phylogenetic information of genus
Entomoderes (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 taxon
belongs; Q, quotient of the total information for the whole group; W, weight for each taxon;
P, percentage.
INSECT BIODIVERSITY OF MONTE DESERT
89
Figure 7. Cladogram and values for species according to phylogenetic information of genus
Enoplopactus (Coleoptera: Curculionidae). Legend as Figure 6.
Figure 8. Cladogram and values for species according to phylogenetic information of genus
species of genus Bulnesia (Zygophyllaceae). Legend as Figure 6.
Figure 9. Cladogram and values for species according to phylogenetic information of species of
genus Cnemalobus (Coleoptera: Carabidae). Legend as Figure 6.
S. ROIG-JUN ENT ET AL.
90
Figure 10. Cladogram and values for species according to phylogenetic information of species of
genus Pompilocalus (Hymenoptera: Pompilidae). Legend as Figure 6.
Table 4. Percentages of importgance of the areas based on six genera used in this
analysis
Taxa
Entomoderes
Enoplopactus
Bulnesia
Cnemalobus
Pompilocalus
Doeringiella
Total
Chaco
12·9
32·5
36·1
3·0
9·6
33·6
21·2
Northern Central Southern Uspallata PenmH nsula Others
Monte Monte Monte Calingasta Valdés
areas
42·6
47·5
31·4
36·3
6·5
10·3
29·1
12·4
20·0
3·8
3·0
9·8
8·2
9·5
4·1
—
—
9·0
6·7
16·5
6·0
1·5
—
—
—
3·3
5·2
1·6
—
—
—
6·0
4·9
1·4
2·0
26·0
—
32·2
42·2
50·0
21·0
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 of
insects and plants: Entomoderes Solier (Tenebrionidae; Flores & Roig-Jun 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-Jun ent & Flores, 1995; Fig. 9), Pompilocalus Roig-Alsina (Pompilidae; RoigAlsina, 1989a; Fig. 10), and Doeringiella Holmberg (Anthophoridae; Roig-Alsina,
1989b, Fig.11). Figures 6}11 show cladograms of these genera and the distribution of
each species with the values, following Vane-Wright et al. (1991). By adding the values
for all the species inhabiting the same area, we assigned a value to that particular area
INSECT BIODIVERSITY OF MONTE DESERT
91
Figure 11. Cladogram and values for species according to phylogenetic information of species of
genus Doeringiella (Hymenoptera: Anthophoridae). Legend as Figure 6.
(Table 4). The value of species occurring in more than one area was divided by the
number of areas where the species occurs, and this resulting value was added to each of
the areas where it occurs. According to these results (Table 4), the areas are ranked for
priority in conservation as follows: (1) Northern Monte, 29·1% importance; (2) Chaco,
21·2%; (3) Central Monte, 9·5%; (4) Southern Monte, 6·0%; PenmH nsula de ValdeH s, 2·0%;
and Uspallata-Calingasta valley, 1·6%.
All the reserves currently placed in the biogeographic province of the Monte are
within the Central and Southern Monte areas, the Northern area being without any
protected surface (Roig-Jun ent & Claver, 1999). Paradoxically, the results of the present
paper show the Northern area of the Monte as the most important for conservation.
92
S. ROIG-JUN ENT ET AL.
Therefore, we emphasize the necessity for setting reserves in the northern Monte area to
protect several endemic species, allowing maintenance of as much as possible of the
biodiversity.
Conclusions
The results of the present study lead to the conclusion that the alfa diversity of the Monte
is lower than the alfa diversity of the Chaco, but that the Monte area has a higher
proportion of endemic taxa than Chaco. Consequently, although the traditional hypothesis that Monte is an impoverished Chaco may be true, the high proportion of species
that 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 available
information on distributional patterns of these Monte insects is still very incomplete,
showing a serious lack of information. Based exclusively in four rather well-known
Coleoptera families, five areas of endemism are proposed for the Monte. These areas are
distributed latitudinally from the north to the south, the Central and Southern areas
being larger than the Northern area, Uspallata-Calingasta valley, and PenmH nsula de
Valdés. The lack of information, together with the increasing human activity, emphasize
the necessity for survey research in conservation. The conservation value for different areas of endemism herein proposed have been evaluated, with the Northern area of
Monte deemed to present the highest priority for conservation. Paradoxically, no
protected area is currently located within this area, and this highlights the need to set
conservation areas in the Northern Monte (i.e. in Catamarca, TucumaH n and Salta
provinces).
The present knowledge of the insects of the Monte is still too scarce to allow complete
comparative studies, for example between Monte and Chaco or Patagonia. A more
exhaustive study of the Monte biodiversity will require collaboration between several
research 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 Investivaciones
CientmH ficas y TeH cnicas, Argentina (CONICET, PIP 4678). The National Geographic Society also
supported part of the field work in Patagonian areas. We thank Henry Noel Le HoueH rou, Charles
A. Triplehorn, Jorge Crisci, Juan JoseH Morrone-Luppi, and Esperanza Cerden o for their comments on the manuscript. MarmH a Elena Soler helped with the English.
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