ARTÍCULOS ORIGINALES

The Triassic insect fauna from Argentina. Blattoptera and Coleoptera from the Ischichuca Formation (Bermejo Basin), La Rioja Province

Rafael Gioia Martins-Neto¹ and Oscar Florencio Gallego²

¹Programa de Pós-graduação em Ciências Biológicas, Comportamento e Biologia Animal, Universidade Federal de Juiz de Fora. Centro de Ensino Superior de Juiz de Fora. Sociedade Brasileira de Paleoartropodologia-Campus Universitário- Martelos. 36036-900, Juiz de Fora, Minas Gerais, Brasil. martinsneto@terra.com.br
²Micropaleontología, Facultad de Ciencias Exactas y Naturales y Agrimensura-Universidad Nacional del Nordeste y Área Paleontología, Centro de Ecología Aplicada del Litoral - Consejo Nacional de Investigaciones Científicas y Técnicas. Casilla de Correo 128, 3400 Corrientes, Argentina. ofgallego@live.com.ar

Abstract. Fossil insect taxa from the Ischichuca Formation (late Middle Triassic to early Late Triassic), La Rioja Province (Argentina) are described. One new genus and six new species are proposed: Hermosablatta pygmaea sp. nov. (Blattoptera, Mancusoblattidae), Ademosyne umutu sp. nov., Ischichucasyne cladocosta sp. nov. (Coleoptera, Permosynidae), Argentinosyne ischichucaensis sp. nov. (Coleoptera, Schizocoleidae), Babuskaya elaterata gen. et sp. nov. (Coleoptera, Elateridae?) and Argentinocupes sara sp. nov. (Coleoptera, Cupedidae?). Other previously described Triassic insect species, such as Ademosyne punctuada Martins-Neto and Gallego, Argentinosyne frenguellii Martins-Neto and Gallego, and Argentinocupes pulcher Martins-Neto and Gallego are reported for the first time from this formation.

Resumen. La fauna de insectos triásicos de la Argentina. Blattoptera y Coleoptera de la Formación Ischichuca (cuenca del Bermejo), provincia de La Rioja. En esta contribución se describen nuevos insectos fósiles de la Formación Ischichuca (Triásico Medio alto a Triásico Superior bajo), provincia de La Rioja (Argentina). Se proponen un género y seis especies nuevas, Hermosablatta pygmaea sp. nov. (Blattoptera, Mancusoblattidae), Ademosyne umutu sp. nov., Ischichucasyne cladocosta sp. nov. (Coleoptera, Permosynidae), Argentinosyne ischichucaensis sp. nov. (Coleoptera, Schizocoleidae), Babuskaya elaterata gen. et sp. nov. (Coleoptera, Elateridae?) y Argentinocupes sara sp. nov. (Coleoptera, Cupedidae?). Otras especies de insectos triásicos descriptos previamente son reportados por primera vez para esta formación, a saber: Ademosyne punctuada Martins-Neto y Gallego, Argentinosyne frenguellii Martins-Neto y Gallego y Argentinocupes pulcher Martins-Neto y Gallego.

Key words. Blattoptera; Coleoptera; Ischichuca Formation; Triassic; Argentina.

Palabras clave. Blattoptera; Coleoptera; Formación Ischichuca; Triásico; Argentina.

Introduction

In this paper, the third report of fossil insect remains (Hexapoda, Insecta) from the Ischichuca Formation (quebrada de Ischichuca Chica locality, La Rioja Province, Argentina) is presented (figure 1.1). This is the first record of insects of the orders Blattoptera (cockroaches) and Coleoptera (beetles) from this geological unit. Martins-Neto and Gallego (2001, 2006) described the first known insects from the Ischichuca Formation (Lariojaprosbole melchori Martins-Neto and Gallego and Gallegomorphoptila kotejai Martins-Neto and Gallego, Auchenorrhyncha).

Figure 1. 1, Geologic map of the Bermejo Basin (modified from Stipanicic and Bonaparte, 1979 and Kokogian et al., 2001) / mapa geológico de la cuenca del Bermejo (modificado de Stipanicic y Bonaparte, 1979 y Kokogian et al., 2001). 2, Stratigraphic section from the quebrada Ischichuca Chica, La Rioja province, with the stratigraphic position of the described insects (adapted from Melchor, 2002) / sección estratigráfica de la quebrada Ischichuca Chica, provincia de La Rioja, con la posición estratigráfica de los insectos descriptos (adaptado de Melchor, 2002). Species recorded in each insect level / Especies registradas en cada uno de los niveles con insectos (IL), IL1. Hermosablatta pygmaea sp. nov., Ademosyne umutu sp. nov., Argentinosyne frenguellii Martins-Neto and Gallego and Argentinocupes sara sp. nov., IL2. Ischichucasyne cladocosta sp. nov., Gallegomorphoptila kotejai Martins-Neto and Gallego and Lariojaprosbole melchori Martins-Neto and Gallego. IL3-4. Argentinosyne ischichucaensis sp. nov., IL-5. Ademosyne punctuada Martins-Neto and Gallego and IL6. Babuskaya elaterata gen et sp. nov.

The previously described Triassic insect species from Argentina were reported by Gallego (1997), Gallego and Martins-Neto (1999), Martins-Neto and Gallego (1999, 2001, 2006) and Martins-Neto et al. (2003, 2005, 2006a, 2006b, 2007, 2008).

Material and methods

The terminology adopted here for Blattoptera wing veins follows Kukalova-Peck (1991) and Martins-Neto et al. (2005): ScP, posterior subcosta; RA, anterior radius; RP, posterior radius; MA, anterior media; MP, posterior media; CuA, anterior cubitus; CuP, posterior cubitus; f, height from the main CuP curvature to d, in relation to the tegmen base; d: Anal area diagonal, from CuP origin at CuP distal extremity, at the anal margin. The terminology used here for Coleoptera elytron follows Ponomarenko (1969) and Martins-Neto et al. (2006b).
The repository and institutional abbreviations used here are PULR-I: Paleontology Collection, Museo de Ciencias Naturales, Universidad Nacional de La Rioja, La Rioja, Argentina, and CTES-PZ: Paleozoological Collection, Facultad de Ciencias Exactas y Naturales y Agrimensura, Universidad Nacional del Nordeste, Corrientes, Argentina.

Geological setting

The insect fauna described in this paper comes from the Ischichuca Formation, which belongs to the Agua de la Peña Group of the Bermejo rift basin (figure 1.1). The Ischichuca Formation is predominantly composed of shallow and deep lacustrine facies with progradational deltaic successions (Melchor, 1998). In particular, insect remains came from dark brown to olive-green claystones with abundant plant remains from the middle to the basal upper parts of the unit. This interval is interpreted as a shallow, partially saline lake (perennial playa lake association facies, L2 from Melchor, 2005, 2007) to a deep freshwater lake (deep freshwater lake association facies, L3 from Melchor, 2005, 2007). The Ischichuca Formation continental palynologic assemblage is closely comparable to those of the Ipswich Microflora from Australia (Zavattieri and Melchor, 1999). Macroscopic plant remains from this unit were included by Spalletti et al. (1999) in the Dyctiophyllum castellanosii, Johnstonia stelzneriana, Saportaea dichotoma (CSD) association biozone of early Middle Triassic age. Disagreement exists on the age of the Ischichuca Formation, because most authors considered that this unit is approximately of the same age as the Potrerillos Formation (Stipanicic and Bonaparte, 1979; Stipanicic, 1983; Kokogian et al., 1999). However, in the recent chronostratigraphic scheme of Spalletti et al. (1999) the Ischichuca Formation is restricted to the lower part of the Middle Triassic. Conversely, Zavattieri and Melchor (1999) suggested that the age of the Ischichuca Formation, based on the palynological content, is late Ladinian to early Carnian (see also Bossi et al., 2002, p. 146-147 and Stipanicic and Marsicano, 2002, Anexo 13, p. 340-343). This is in agreement with a previous palynological assessment of a Carnian age for the overlying Los Rastros Formation (Zavattieri and Batten, 1996). According to this assessment, a preliminary analysis based on the continental invertebrate biota (insects and conchostracans) suggests that the lower Cacheuta, the upper Los Rastros, the middle-upper Ischichuca (all from Argentina) and the lower "Santa Juana" Formation (from Chile) assemblages are similar and probably, in part, of the same age (Gallego and Martins Neto, 2005).

Systematic paleontology

Order Blattoptera Brunner, 1882
Superfamily Blattoidea sensu Handlirsch, 1906
Family Mancusoblattidae Martins-Neto and Gallego (Martins-Neto et al., 2005)

Genus Hermosablatta Martins-Neto and Gallego (Martins-Neto et al., 2005)

Type species. Hermosablatta pectinata Martins-Neto and Gallego (Martins-Neto et al., 2005), p. 714, figs. 3.N-Q; 5.D.

Hermosablatta pygmaea sp. nov. Figures 2.1, 3.1

Figure 2. 1-2, Schematic drawing showing some of the main diagnostic wing characters of two Hermosablatta species / dibujo esquemático de los principales caracteres diagnósticos alares de dos especies de Hermosablatta; 1, Hermosablatta pygmaea sp. nov., drawn from holotype / dibujado del holotipo, PULR-I 319; 2, Hermosablatta pectinata Martins-Neto and Gallego drawn from the holotype / dibujado del holotipo, PULR-I 284, (modified from / modificado de Martins-Neto et al., 2005, Fig. 3N); 3, Ademosyne punctuada Martins-Neto and Gallego, drawn from supplementary material / dibujado del material suplementario, PULR-I 315 (with a detail of the punctate costae and the granulate ornamentation between them / con un detalle de las costillas punteadas y de la ornamentación granulada entre ellas); 4-5, Argentinosyne ischichucaensis sp. nov., drawn from holotype / dibujado del holotipo, PULR I316 part /parte (4) and from the paratype / y del paratipo, PULR-I 316a counterpart / contraparte (5), respectively (with a detail of the granulate ornamentation) / respectivamente (con un detalle de la ornamentación granulada); 6-7, Ischichucasyne cladocosta sp. nov., drawn from holotype / dibujado del holotipo, PULR-I 317; 6, showing the bifurcated veins at the basal area / mostrando las venas bifurcadas en el área basal; 7, with a detail of the striated ornamentation between costae / con un detalle de la ornamentación estriada entre las costillas; 8, Babuskaya elaterata sp. nov., drawn from holotype / dibujado del holotipo, PULR-I 318. Terminology / terminología: CuA, CuP, anterior and posterior cubitus, respectively / cubital anterior y posterior, respectivamente; MA, MP, anterior and posterior media, respectively / media anterior y posterior, respectivamente; RA, RP, anterior and posterior radius, respectively / radial anterior y posterior, respectivamente; ScP, posterior sub-costa / subcostal posterior; m-cu, media-cubitus crossvein / vena intercalar media-cubital; r-m, radius-media cross-vein / vena intercalar radial-media. Scale bar / escala =1 mm (except in / excepto en A = 0,5 mm).

Figure 3. 1, Hermosablatta pygmaea sp. nov., holotype / holotipo, PULR-I 319; 2, Ademosyne punctuada Martins-Neto and Gallego, material / material, PULR-I 340; 3, Ademosyne umutu sp. nov., holotype / holotipo, PULR-I 278; 4, Argentinosyne frenguellii Martins-Neto and Gallego, material / material, PULR-I 341; 5, Argentinosyne ischichucaensis sp. nov., holotype / holotipo, PULR-I 316; 6, Ischichucasyne cladocosta sp. nov., paratype / paratipo CTES-PZ 7322; 7, Babuskaya elaterata sp. nov., holotype / holotipo, PULR-I 318; 8, Argentinocupes pulcher Martins-Neto and Gallego material / material, PULR-I 342; 9, Argentinocupes sara sp. nov., holotype / holotipo, PULR-I 315. Scale bar / escala = 1 mm (except in / excepto en 1 = 0.5 mm).

Etymology. From pygmaeus, -a (Latin), refers to the small size of the specimen.

Holotype. PULR-I 319.
Type locality. Quebrada de Ischichuca Chica, La Rioja Province, Argentina.
Type stratum. Middle third (Isch-65) from the Ischichuca Formation, (IL 1, figure 1.2).

Age. Late Middle Triassic to early Late Triassic.
Diagnosis (based on tegmen fragment): Hermosoblatta with: 1) RP with just 3 secondary branches (5 branches in Hermosablatta? sp. and 7 branches in H. pectinata and H. crassatella). 2) RA with 4 secondary branches (unbranched in H. pectinata and Hermosablatta? sp. and with 1 branch in H. crassatella), reaching the costal area after the midlength level (at 1/3 of tegmen base in H. pectinata). 3) Unbranched MA which origin is before the tegmen midlength (at 1/3 of tegmen base in H. pectinata and H. crassatella). 4) Three branched CuA (four branched in H. pectinata and H. crassatella and six branched in Hermosablatta? sp.), all branches dichotomous, pectinated and oblique to anal margin. 5) Last CuA distal secondary branch origin before MA origin. 6) CuP trespasses the tegmen midlength. 7) Large anal area, occupying more than 70% of the tegmen width.
Description. The tegmen (male?) fragment is 0.85 mm long (total estimated 1.20 mm), lacking the distal and proximal extremities, and 0.55 mm wide (estimated 0.6 mm because the distal extremity of RA and last distal secondary branch of CuA are almost entirely present), probably two times longer than wide. ScP is not preserved but judging by the RA fragment, surely ScP might cross the midlength of the tegmen. RA, has 4 secondary branches. Additionally, H. pygmaea sp. nov. exhibits a small number (3) of RP secondary branches compared with the other known species of the genus. MA is unbranched in this species and MA origin is at 1/3 of the tegmen base. The anal area is not preserved in this specimen but judging by the preserved CuA morphology whose secondary branches are pectinated and oblique to anal margin, CuP must be long, probably occupying approximately 70% of the tegmen width (as in H. crassatella Martins-Neto and Gallego - the more distal secondary branch of CuA is closer than the first third of the tegmen width). The f parameter is at ¼ of the CuP base.
Discussion. Hermosablatta pygmaea sp. nov. has a tegmen two times longer than wide, with ScP distally multibranched, the last branch trespassing the mi-dlength of the tegmen, very far from CuP distal extremity (as in Hermosablatta pectinata Martins-Neto and Gallego, H. crassatella Martins-Neto and Gallego and Hermosablatta? sp. described from the Los Rastros Formation, Bermejo Basin, La Rioja, Argentina, Martins Neto et al., 2005). MA is unbranched (as in other Hermosablatta species); MA origin at 1/3 of the tegmen base (as in H. crassatella). Hermosablatta pygmaea sp. nov. shares with H. pectinata Martins-Neto and Gallego and H. crassatella Martins-Neto and Gallego RA the last branch reaching the costal margin after the midlength of the tegmen, RA with 4 secondary branches, unbranched MA and its origin at midlength of the tegmen and a large anal area, occupying around 50% to 70% of the tegmen width with CuA secondary branches pectinated and oblique to anal margin. Hermosablatta pygmaea sp. nov. differs from other known species of the genus in the small number of RP secondary branches (3) compared with the 7 branches presented in H. pectinata and H. crassatella. H. pygmaea sp. nov. also differs with both species in the MA origin and CuP distal extremity perpendicularly aligned to both costal and anal margins, with CuA oblique in H. pygmaea. Due to this fact the new species probably shares with the family Delpuenteblattidae the long CuP with a typical sigmoid morphology. Comparisons made with other Gondwanan Triassic species demonstrate that: Mancusoblatta pulchella Martins-Neto and Gallego (Los Rastros Formation, Bermejo Basin) differs in ScP branch restricted to 1/3 of the tegmen length. "Triassoblatta" cargnini Pinto and Ornellas, 1974 (Santa Maria Formation, southern Brazil) and "Triassoblatta" grandis Dodds, 1949 (Australian Triassic) differ in the presence of massive intercalary veins. "T." triquestra Dodds, 1949, "T." deiscens Dodds, 1949 and "T." intramedia Dodds, 1949 (all from the Australian Triassic), differ by having no distinct RA.
Remarks. Based on direct and indirect evidences, the present fragment is attributed to the genus Hermosablatta Martins-Neto and Gallego. The attribution to a new species is mainly due to the extremely small size of the specimen (this could be the smallest known species of Blattoptera). This small size can have at least two explanations. It might be a brachypterous Blattoptera, but the lack of preserved body elements does not permit us to be conclusive in this respect. Second, it might be a stressed Blattoptera (maybe due to palaeoecological problems - ecological nanism for example, see Martins-Neto, 2006).

Order Coleoptera Linnaeus, 1758
Family Permosynidae Tillyard, 1924 (includes Ademosynidae Ponomarenko, 1969)

Remarks. According to Ponomarenko (2003) isolated coleopteran elytra with the presence of 11 longitudinal punctuate striae, short scutellar striae and submarginal striae, first striae from sutural margin, composite, reaching the elytron apex, eleventh striae bordering the anteapical margin, belong to the genus Permosyne Tillyard, 1924 rather than to Ademosyne Handlirsch, 1906. It is due to the fact that the holotype of the type species of the latter genus is not an isolated elytron but a complete beetle and, therefore, should be treated within a natural classification. Formal "families" were proposed for isolated elytra: Permosynidae Tillyard for elytra with sulci and Schizocoleidae Rohdendorf for smooth elytra or elytra without tegular rows of punctures. The holotype of typical species of genus Ademosyne has ventral structures of body, and Ponomarenko (1969) have proposed the family Ademosynidae for whole rests only. Many generic names were proposed for different types of isolated elytra. Most part of elytra described as Permosynidae (and Ademosynidae) do not belong to archostematan beetles but can be referred to Adephagian and Polyphagian (Ponomarenko, 2003, 2006). Due to this confused systematic panorama, we consider that it is not necessary to modify the taxonomic assignment for the present insect material until this situation is clarified. Nevertheless, the Triassic coleopteran elytra described by Martins-Neto et al. (2006a, 2006b) and in the present paper as Ademosyne differ from the diagnosis of Permosyne by having 6 to 11 punctate to smooth longitudinal striae, instead of 11 longitudinal punctuate striae (including a short scutellar and a submarginal striae) in the latter (Ponomarenko, 2003).

Genus Ademosyne Handlirsch, 1906

Type species. Ademosyne major Handlirsch, 1906, p. 402, Pl. 39, Fig. 14.

Ademosyne punctuada Martins-Neto and Gallego (in Martins Neto et al. 2006b) Figures 2.3, 3.2

Material. PULR-I 340 (Isch-114, IL 5, figure 1.2).

Locality. Quebrada de Ischichuca Chica, La Rioja Province, Argentina.
Stratigraphic unit. Middle third (Isch-114) from the Ischichuca Formation, (IL 5, figure 1.2).
Age. Late Middle Triassic to early Late Triassic.
Description. Elytron 2.6 mm long as preserved and 1.58 mm wide (relation L/W around 1.6), with narrow lateral border. Six punctate, not convergent costae. Space between costae constituted by small granules homogeneously distributed over the whole elytron surface.
Remarks. This specimen is very similar to others which also occur at the Río Gualo locality, La Rioja Province (Los Rastros Formation) in all observed morphological aspects (Martins-Neto et al., 2006b), only differing by having a relation length/width = 1.6, one of the smallest rate for the genus (1.6 in A. arcucciae Martins-Neto and Gallego). Ademosyne punctuada has a combination of characters present in other Triassic species, such as the L/W ratio (2.47 in A. punctuada; 2.72 in A. hexacostata Martins-Neto and Gallego and 2.47 in A. arcucciae), usually 9 costae (as in A. arcucciae), occasionally 6 (as in A. hexacostata), costae not convergent, subparallel (as in A. hexacostata), and the space between costae bearing small, homogeneously distributed granules (as in all previously described species). The presence of punctate costae in A. punctuada was previously reported for A. parva Dunstan, 1923 and A. brevis Dunstan, 1923 from the Ipswich Series (Australia). Both species differ from A. punctuada in the costae convergent to the elytron apex, L/W ratio (1.8 in A. brevis and 2.5 in A. parva), and general ovate outline.

Ademosyne umutu sp. nov. Figure 3.3

Etymology. Latinized from umutu (Quechua, argentinean native language), little. Femenine.

Holotype. PULR-I 278 (Isch-65, IL 1, figure. 1.2).
Type locality. Quebrada de Ischichuca Chica, La Rioja Province, Argentina.
Type stratum. Middle third (Isch-65) from the Ischichuca Formation, (IL 1, figure 1.2).

Age. Late Middle Triassic to early Late Triassic.
Diagnosis (based on isolated elytron): The main characters of this taxon are: 1) Elytron with narrow lateral border. 2) 7 to 8 costae (9 in A. arcucciae, 11 in A. elongatus, 6 in A. hexacostata), convergent to the posterior elytron extremity (nonconvergent in A. arcucciae, A. elongates and A. punctuada and subparallel in A. hexacostata). 3) Elytron surface with irregularly and concave small sized cells (granulate cells in A. arcucciae, small square granules in A. elongatus, A. punctuada and A. hexacostata), homogeneously distributed.
Description. Elytron, 1.8 mm long and 0.9 mm wide (relation L/W = 2.0), with narrow lateral border and strong triangular outline. Ornamentation constituted by irregularly and concave small-sized row of cells, homogeneously distributed over the whole elytron surface. Anterolateral margin slightly curved; posterolateral margin quite straight. Seven to eight well defined costae converging to the posterior extremity of the elytron.
Discussion. Small sized Ademosyne species are similar to the length and width range of A. arcucciae, differing however by having a relation length/width = 2, the smallest rate for the genus (2.47 +/- 0.28 in A. arcucciae). The ornamentation pattern is less evident than in the other species of the genus. Although just one specimen is known, it exhibits enough diagnostic characteristics to constitute a new species in the genus.

Genus Ischichucasyne Martins Neto and Gallego (in Gallego et al., 2005)

Type species. Ischichucasyne santajuanaensis Martins Neto and Gallego (in Gallego et al., 2005), p. 300-301, text Fig. 2C; Pl. 3, Fig. 7.

Ischichucasyne cladocosta sp. nov. Figures 2.6-7, 3.6

Etymology. Refers to the branching pattern of the elytron costae.

Holotype. PULR I 317, Isch-85, (IL 2, figure 1.2).
Paratype. CTES-PZ 7322, Isch-85, (IL 2, figure 1.2).
Type locality. Quebrada de Ischichuca Chica, La Rioja Province, Argentina.
Type stratum. Middle third (Isch-114) from the Ischichuca Formation, (IL 5, figure 1.2).

Age. Late Middle Triassic to early Late Triassic.
Diagnosis. The main characters of this taxon are: 1) Ademosyne-like elytron shape, with 9 to 11 well defined smooth costae (6 in I. santajuanaensis). 2) Multibranched costae close to the anterolateral margin (trichotomus at the proximal part in I. santajuanaensis), convergent to the elytron base (to the distal border in I. santajuanaensis). 3) Space between costae striated (granulated in I. santajuanaensis). 4) Elytron three and half times longer than wide (four times in I. santajuanaensis). 5) Lateral margin slightly convex and distally convex. 6) Sutural margin slightly straight, wide bordered. 7) Apex rounded and narrow.
Description. Elytra with elongated shape, 7.3 mm long and 2.08 mm wide (relation L/W = 3.5), with narrow lateral border. Costae 9 to 11, smooth, divergent and proximally multibranched. Space between costae striated, homogeneously distributed over the whole elytron surface.
Discussion. Ischichucasyne cladocosta sp. nov. differs from I. santajuanaensis Martins Neto and Gallego (in Gallego et al., 2005; from the Upper Triassic, Chile) by having an elytron three and half times longer than wide (4 in I. santajuanaensis), and 9 to 11 costae (6 in I. santajuanaensis).

Family Schizocoleidae Rohdendorf, 1961

Genus Argentinosyne Martins-Neto and Gallego (in Martins-Neto et al., 2006b)

1997. Tillyardopsis Dunstan. Gallego: 514; lám. IH, partim.
1997. Mesostigmodera? Etheridge and Olliff. Gallego: 514; lám. IJ, partim.
1999. Mesostigmodera Etheridge and Olliff. Gallego and Martins-Neto: 87; fig. 6, partim.

Type species. Argentinosyne frenguellii Martins-Neto and Gallego (in Martins-Neto et al., 2006b), figs. 3.A1-A5; 4.D.

Diagnosis emend. (based on isolated elytron). The main characters of this taxon are: 1) Elytron without costae and ornamentation constituted by homogeneous granules or punctae. 2) Elytron with elongated shape, two to four times longer than wide, widest at its midlength. 3) Elytron dimensions with a great range of variations. 4) Lateral margin sigmoid and bordered, strongly arcuate apically. 5) Sutural margin bordered slightly straight to irregularly convex. 6) Elytron apex rounded.
Discussion. The genus Argentinosyne is assigned by Martins-Neto et al. (2006a, 2006b) to the family Permosynidae. In Martins-Neto et al. (2008), based on new morphological evidence (given by the specimen described here) and according to Ponomarenko's proposal (2006), the authors consider that this morphogenus (of isolated elytra), with smooth elytra (lacking striae on its surface) or elytra without tegular rows of puncture, belongs to the Schizocoleidae Rohdendorf, 1961.
Argentinosyne differs from the Australian Triassic genera, Ademosyne Handlirsch, 1906 and Platycrossos Dunstan, 1923 by the absence of costae (well-defined in Ademosyne and Platycrossos), and also in the great size and elytra shape of largest specimens. The elytron length varying from 1.2 to 18.0 mm (media 14.88 mm, standard deviation +/- 1.80 mm), and width varying from 0.9 to 3.5-5.5 mm (media 4.40 mm, standard deviation +/- 0.65 mm). The rate length/width varying from 3.3 to 4.2 (media 3.48 mm, standard deviation +/- 0.46).
Noncostate genera from Australia, as Tillyardiopsis Dunstan, 1923, Mesostigmodera Etheridge and Olliff, 1890 and Reeveana Dunstan, 1923 slightly resemble Argentinosyne (Gallego ,1997 and Gallego and Martins-Neto,1999). The three Australian taxa differ from Argentinosyne in the elytron shape (equal sutural and lateral borders and boat-like outline in Reeveana and Tylliardiopsis), broad sutural border and an acute apex (in Mesostigmodera) and ornamentation (smooth only in Reeveana, with sigmoid rows of granules in Mesostigmodera and convergent in Tylliardiopsis).

Argentinosyne frenguellii Martins-Neto and Gallego (in Martins Neto et al., 2006b) Figure 3.4

Material. PULR-I 341 (Isch 65, IL 1, figure 1.2).

Locality. Quebrada de Ischichuca Chica, La Rioja Province, Argentina.
Stratigraphic unit. Middle third (Isch-65) from the Ischichuca Formation, (IL 1, figure 1.2).
Age. Late Middle Triassic to early Late Triassic.
Description. Specimen without well-delimited costae, around three times longer than wide. Elytron 3.0 mm long and 0.9 mm wide (relation L/W = 3.33), with slightly lateral border. Sutural margin slightly convex and lateral margin convex, apically arcuate. Wide elytron apex. Ornamentation constituted by very small punctae homogeneously distributed over the whole elytron surface.
Remarks. The specimen described here is much smaller than the type specimen of A. frenguellii Martins Neto and Gallego (from Los Rastros Formation), and very similar to the figured specimen (PULR-I 225, fig. 3.A2) in Martins-Neto et al. (2006b). The Australian Triassic species Tylliardopsis tubercula-ta Dunstan, 1923 and T. variotuberculata Dunstan, 1923 differ from the new specimen in having a boat-like elytron shape, ornamented with 9 to 16 conver-gent rows of granules (more than 16 straight rows in A. frenguellii) and also in the L/W ratio (2.6 in both species). Mesostigmodera typica Etheridge and Olliff, 1890 from the Australian Triassic, differs from A. frenguellii in the broad sutural border and the acute apex, the elytron ornamented with sigmoid rows of granules and the L/W ratio (3.1 in M. typica).

Argentinosyne ischichucaensis sp. nov. Figures 2.4-5, 3.5

Etymology. Refers to the Ischichuca Formation, where the material comes from.

Holotype. PULR I 316, Isch-139, (IL 4, figure 1.2).
Paratype. CTES-PZ 7323, 7323a and PULR I 316a, Isch-107, (IL 3, figure 1.2).
Type locality. Quebrada de Ischichuca Chica, La Rioja Province, Argentina.
Type stratum. Middle third (Isch-107, 139) from the Ischichuca Formation, (IL 3, 4, figure 1.2).

Age. Late Middle Triassic to early Late Triassic.
Diagnosis. (based on both elytra) The main characters of this taxon are: 1) Elytron surface homogeneously ornamented with medium-sized granules (smooth in A. gualoensis and A. losrastrosensis and small granules in A. frenguellii, rugose waved granules in A. gonaldie and rugose in A. rugosa), without well-defined costae. 2) Elytron with rounded shape (elliptical elongated shape in A. gualoensis and A. rugosa), three times longer than wide (two times in A. losrastrosensis, two and half times in A. gonaldie, four times in A. frenguellii). 3) Elytron with narrow lateral border (conspicuous in A. gonaldie and A. frenguellii). 4) Lateral margin continuously rounded, apically acute. 5) Sutural margin slightly straight. 6) Antero-lateral margin slightly curved; posterolateral margin quite straight. 7) Apex with a general rounded outline (acute in A. punctuada, A. rugosa and A. losrastrosensis).
Description. Elytra length varying from 5.5 to 6.5 mm and width varying from 1.8 to 2.2 mm (relation L/W = 2.9 to 3.1), with narrow lateral border. Elytron with rounded shape, three times longer than wide. Lateral margin continuously rounded, apically acute. Sutural margin slightly straight. Anterolateral (humeral) margin slightly curved; posterolateral margin quite straight. Apex with a general rounded outline. Ornamentation constituted by medium-sized granules homogeneously distributed over the whole elytron surface.
Discussion. Similar to Argentinosyne gualoensis Martins-Neto and Gallego described from the Los Rastros Formation (in Martins Neto et al., 2006b) in most morphometrical aspects, but differing by having rather medium-sized granules on the elytron surface (small granules in A. frenguellii and smooth in A. gualoensis).

Family Elateridae? Leach, 1815

Remarks. According to Carpenter (1992, p. 303-305) the diagnosis of the family is: « Small to large, elongate beetle, body usually slighty flattened. Antennae usually serrate, less commonly filiform or pectinate ; pronotum large with a pronotal process fitting into a cavity (click mechanism) on mesosternum, hind angles of pronotum acute and projecting posteriorly, fore coxal cavities open posteriorly ; all tarsi with 5 segments ; abdomen with 5 visible sternites. Adults on foliage ; larvae mainly phytophagous on roots, some carnivorous. Jur. - Holo. » We support the assigment to a formal family Elateridae because, this elytra is not broken, the outline and the convex basal margin are regular, and it does not show a broken surface or margin. On the other hand, this placement is also supported by similarities with other Triassic material. Although, the specimen lacks the majority of the diagnostic characters of the family, it presents the «hind angles of pronotum acute…» according with the feature of the basal area, with more or less right angles.

Babuskaya gen. nov.

Type species. Babuskaya elaterata sp. nov.

Etymology. Refers to Babuska (Russian), designation for grand-mother (in diminutive).
Diagnosis. The main characters of this taxon are: 1) Elytron triangular in shape, with rugose surface. 2) Humeral margin slightly convex. 3) Apical margin notably acuminated, with a remarkable posterolateral marginal border.
Discussion. Babuskaya gen. nov. is similar to Elaterites Heer, 1847 recorded from the Australian Triassic (Dunstan, 1923) and an unnamed material from the Triassic of Germany (Brauckmann and Schluter, 1993; Fig. 18) in the general morphological aspects (elytron triangular), but greatly differs by having a prominent posterolateral border, a rugose surface and costae not defined. Gemelina Martins-Neto and Gallego from the Los Rastros Formation (in Martins-Neto et al., 2006b) differs in the large size of the elytron, apex slightly acuminate, posterolateral margin straight and granulated surface. Cardiosyne Martins-Neto and Gallego from the Los Rastros Formation (in Martins-Neto et al., 2006b) differs in the heart shape of the elytron, with smooth surface, proximal margin roof-like with a thick and conspicuous border.

Babuskaya elaterata sp. nov. Figures 2.8, 3.7

Etymology. Refers to the triangular, elaterid-like, elytron shape.

Holotype. PULR I 318 (Isch-125; IL 6, figure 1.2).
Type locality. Quebrada de Ischichuca Chica, La Rioja Province, Argentina.
Type stratum. Middle third (Isch-125) from the Ischichuca Formation, (IL 6, figure 1.2).

Age. Late Middle Triassic to early Late Triassic.
Diagnosis. The main characters of this taxon are: 1) Elytron triangular in shape, with rugose surface. 2) Humeral margin slightly convex. 3) Apical margin notably acuminated, with a remarkable posterolateral marginal border. 4) Elytron 2 times longer than wide.
Description. Elytron triangular, 6.0 mm long and 3.0 wide (relation L/W = 2.0), with thick lateral border. Humeral margin slightly convex (close to roof-like) and apex accuminated. Anterolateral margin straight and posterolateral margin parallel, distally (around 1/3 of the apex) converging to the anterolateral one. Ornamentation constituted by transversal rugose undulations, homogeneously distributed on the whole elytron surface.

Family Cupedidae? Laporte, 1836

Remarks. According to Carpenter (1992, p. 285-286) the diagnosis of the family is: "Small to large beetles, usually elongate and flattened or cylindrical, antennae with eleven segments, of diverse form and length, abdomen with 5 distinct sternites. Elytra with distinct venation, all main veins present except CuP and A1; rows of cells present between main veins. Trias - Holo". Labandeira (1994) proposed a Permian to Recent record for this family. The studied material only lacks sternite segments and antennae characters, being the others diagnostic characters all present. However our material lacks recent cupedid synapo-morphies, which is typical for this group of fossils, because they are preserved generally as disarticulated material and lack soft parts of diagnostic importance.

Genus Argentinocupes Martins-Neto and Gallego (in Martins-Neto et al., 2006b)

Type species. Argentinocupes pulcher Martins-Neto and Gallego (in Martins-Neto et al., 2006b), figs. 3.E; 5.E.

Diagnosis emend. The main characters of this taxon are: 1) Elytron elliptical with straight to arcuate outline, with 7 to 10 slightly curved granulated costae. 2) Space between costae filled by 8 to 11 homogeneous rows of square granulated ornamentation.
Discussion. Similar to Simmondsia Dunstan, 1923 from the Australian Triassic (Ipswich Series) and Moltenocupes Zeuner, 1961 from the Triassic Molteno Formation (South Africa) in its ornamentation pattern (homogeneous rows of square granulated ornamentation). However, it differs in the square constituted by depressions or alveolae (in Simmondsia), and in the number of costae (7 to 10 in Argentinocupes, 9 in Simmondsia, 10 in Moltenocupes). Additionally Argentinocupes has costae slightly curved (quite straight in Simmondsia, straight upward and curved downward in Moltenocupes). Also, Argentinocupes (probably A. abdalai Martins-Neto and Gallego, in Martins-Neto et al., 2006b) resembles the specimen figured by Papier et al. (2005) as Species 21 (Lower-Middle Triassic "Grès à Voltzia", France) by its 8 slightly curved costae and 9 rows of square ornamentation.

Argentinocupes pulcher Martins-Neto and Gallego (in Martins-Neto et al., 2006b) Figure 3.8

Material. PULR-I 342 (Isch 65; IL 1, figure 1.2).

Locality. Quebrada de Ischichuca Chica, La Rioja Province, Argentina.
Stratigraphic unit. Middle third (Isch-65) from the Ischichuca Formation, (IL 1, figure 1.2).
Age. Late Middle Triassic to early Late Triassic.
Diagnosis emend. The main characters of this taxon are: 1) Elytron small with elliptical shape (acute in Simmondsia subpiriformis and Moltenocupes townrowi). 2) Elytron with 7 narrow costae (8 in S. subpiriformis and 11 in M. townrowi). 3) Space between costae filled by 8 homogeneous rows with square-granulated ornamentation (9 regular square in S. subpiriformis and 12 in M. townrowi).
Description. Elytron small, elliptical, apex rounded and base slightly convex. Elytron 2.4 mm long as preserved, and 0.7 mm wide with seven slightly curved granulated costae. Space between costae filled by eight homogeneous rows of square granulated ornamentation.
Remarks. The specimen described here is much smaller than the type specimen of A. pulcher from the Los Rastros Formation. Simmondsia subpiriformis Dunstan, 1923 and Moltenocupes townrowi Zeuner, 1961, the morphologically closest Triassic cupedid-like coleopterans from Gondwana, differ in the ovate elytron shape, more acute elytron apex and a more regular square ornamentation between costae. Also M. townrowi remains include the head, mouth parts, antennae and sternites; its total length (from the head to the elytron apex) is 23 mm.

Argentinocupes sara sp. nov. Figure 3.9

Etymology. Latinized from sara (Quechua, argentinean native language), allusive to the elytron ornament, similar to the ear of corn. Feminine.

Holotype. PULR-I 315 (Isch 65; IL 1; figure 1.2).
Type locality. Quebrada de Ischichuca Chica, La Rioja Province, Argentina.
Type stratum. Middle third (Isch-65) from the Ischichuca Formation, (IL 1, figure 1.2).

Age. Late Middle Triassic to early Late Triassic.
Diagnosis. The main characters of this taxon are: 1) Elytron with arcuate shape (elliptical in A. pulcher and acute in Simmondsia subpiriformis and Moltenocupes townrowi). 2) Elytron with 10 curved granulated costae (7 narrow costae in A. pulcher, 8 in S. subpiriformis and 11 in M. townrowi). 3) Space between costae filled by 11 rows of square granulated ornamentation (8 in A. pulcher and 9 regular square in S. subpiriformis and 12 in M. townrowi).
Description. Elytron 3 mm long as preserved, and 1.3 mm wide, with arcuate shape, ornamented by ten slightly curved granulated costae. Space between costae filled by eleven homogeneous rows of square granulated ornamentation.
Remarks. Argentinocupes sara sp. nov. differs from A. pulcher by the number of the costae (10 in A. sara sp. nov. and 7 in A. pulcher), in the number of rows of square granulated ornamentation (11 and 8, respectively), the elytron shape less arcuate in A. pulcher with the elytron apex acute. The Australian Simmondsia subpiriformis and African Moltenocupes townrowi, the morphologically closest related Triassic cupedid-like coleopterans from Gondwana, differ from the new species in the elytron shape, more acute elytron apex and the more regular square ornamentation between costae.

Discussion

The insect species described here have a typical stratigraphical distribution pattern, but the reason for such a spreading would require larger insect collections. The species Hermosablatta pygmaea, Ademosyne umutu, Argentinosyne frenguellii, Argentinocupes sara (IL1, see figure 1.2), Ischichucasyne cladocosta, Gallegomorphoptila kotejai and Lariojaprosbole melchori (IL2 see figure 1.2) come from a perennial playa lake association facies (L2) while Argentinosyne ischichucaensis (IL3-4, see figure 1.2), Ademosyne punctuada (IL-5, see figure 1.2) and Babuskaya elaterata (IL6, see figure 1.2) come from a deep freshwater lake association facies (L3). The last species comes from a transitional interval to wave-dominated littoral deposits (L4).
The record of specimens of blattopteran (H. pygmaea) and coleopteran (Argentinosyne frenguellii and Argentinocupes pulcher) of small size allow us to interpret this as and ecological response (possibly ecolog-ical dwarfism). This small-sized insects would perhaps be related to stressed environmental conditions (as occurs in the Santana Formation, Lower Cretaceous, Brazil, Martins-Neto, 2006). This is indeed reflected by the presence of evaporitic facies in the initial lacustrine interval of the Ischichuca Formation (Zavattieri and Melchor, 1997; Bellosi et al., 2001). Undoubtedly, these still tentative conclusions need more extensive insect collections and detailed studies to be confirmed.
In a recent paper focused on Triassic coleoptera, Papier et al. (2005) analyze the coleopteran diversity in the Lower-Middle Triassic from the Grès à Voltzi (France). These authors concluded that among 584 specimens, there are 32 "morphospecies". Papier et al. (2005) designated their coleopterans only as unnamed numbered species, because they disagree with the use of binominal names for isolated coleopteran elytra, as the elytron does not have enough diagnostic characteristics for a natural classification. However, Martins-Neto et al. (2006b) show that morphometric parameters are a useful tool for systematic purpose because different coleopteran taxa have different morphometric patterns and for-mally isolated coleopteran elytra can be classified into a parataxonomic system.
According to Papier et al. (2005), the Order Coleoptera is the most diverse order in the "Grès à Voltzia" fauna and they conclude that this group was already much diversified in the beginning of the Triassic. These conclusions agree with preliminary observations of Martins-Neto et al. (2006b), because at least 16 species are recognized among 190 collected specimens for the Middle to Upper Triassic of Argentina. The figured specimens of Papier et al. (2005) show that the "Grès à Voltzia" fauna is composed of eight species of "reticulated forms", probably related to the Permian Taldycupedidae and Triassic Cupedidae and Tricoleidae. The Species 21 (fig. 5.C) resembles the Cupedidae? Argentinocupes abdalai Martins-Neto and Gallego (in Martins-Neto et al., 2006b) from the Cacheuta Formation (Upper Triassic). From the eleven smooth species, only two (25, 27; figs. 6.A, C) resemble the genus Argentinosyne from the Argentinean Triassic. Many of the striated forms (13 species) are similar to Ademosyne Handlirsch (e.g. 1, 3, 4, 6, 7, 10, 13; figs 1.A, C, D; 2.A, B, C, D; 3.B, C, D; 4.A).
The record of coleopterans Argentinosyne frenguellii, Argentinocupes pulcher, Ademosyne punctuada, and the genus Ischichucasyne and the hemipteran Gallegomorphotilinae (Gallego and Martins-Neto, 2005; Gallego et al., 2005; Martins-Neto and Gallego, 1999, 2001, 2006; Martins-Neto et al., 2003, 2006a, b) in both stratigraphic units (Ischichuca and Los Rastros formations) allow us to identify a possible "assemblage biozone" restricted to the late Middle Triassic to early Late Triassic of Argentina. This zone could be extended to the same chronostratigraphic levels of Chile (Santa Juana Formation) and Australia (Ipswich Series) (Gallego and Martins-Neto, 2005). The record of insect of Polycitellidae (Glosselytrodea) and Scytinopteromorpha (Hemiptera), adding the presence of Permosinydae (Coleoptera) and Gallegomorphoptilinae (Hemiptera) in the Triassic studied sequences, supports the tentative definition of a "superzone" that characterize the late Middle Triassic to the early Upper Triassic of Gondwana.

Acknowledgements

The authors are grateful to the reviewers for their helpful comments and suggestions that improved the manuscript; to R.N. Melchor for providing the studied material and important information and suggestions about the sedimentology and stratigraphic provenance of the studied specimens; to J. Schneider for opportune comments, suggestions and criticism on an earlier version of this manuscript; and to A. Krapovicas for his help with the Quechua language terms. Also to G.Barrios for making the digital figures and M.E. Gonaldi from the Museo de Ciencias Naturales for her assistance with the catalogue of the specimens. Very special thanks to our colleagues, T. DeVries, S. Nielsen, K. Adami-Rodrigues and W. Volkheimer for revised the last version of the manuscript, and Juanita Vallejos for helping with the English revision in the first steps of this paper. This work was partially supported by the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET-Argentina), Grant 5581, the Secretaría General de Ciencia y Técnica, Universidad Nacional del Nordeste (Grant PI-64/04, PI-075/07) and the Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT) and Universidad Nacional del Nordeste (PICTO-UNNE 226) to O.F.G.

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Recibido: 16 de noviembre de 2006.
Aceptado: 7 de marzo de 2009.