A Revision of the Argentinean Endemic Genus Eucranium Brulléé (Coleoptera: Scarabaeidae: Scarabaeinae) with Description of one New Species and New Synonymies

The South American genus Eucranium Brulléé has been revised and now includes six species: E. arachnoides Brulléé, E. belenae Ocampo new species, E. cyclosoma Burmeister, E. dentifrons Guéérin-Mééneville, E. planicolle Burmeister, and E. simplicifrons Fairmaire. Eucranium pulvinatum Burmeister is a new junior synonym of Eucranium arachnoides Brulléé, and Eucranium lepidum Burmeister is a new junior synonym of E. dentifrons Guéérin-Mééneville. The following lectotypes and neotypes are designated: Eucranium pulvinatum Burmeister, lectotype; Eucranium planicolle Burmeister, lectotype; Psammotrupes dentifrons Guéérin-Mééneville, neotype; and Eucranium lepidum Burmeister, neotype. Description of the genus and new species, diagnosis and illustrations, and distribution maps are provided for all species. A key to the species of this genus is provided, and the biology and conservation status of the species are discussed.


Introduction
The tribe Eucraniini (Scarabaeidae: Scarabaeinae) constitutes a monophyletic group and includes four genera, Anomiopsoides Blackwelder, Ennearabdus van Lansberge, Eucranium Brullé, and Glyphoderus Westwood (Zunino 1983;Philips et al. 2002;Ocampo and Hawks 2006). This work showed that Eucranium consists of six species. The genus is endemic to Argentina and distributed in the Monte and Chacoan biogeographic provinces (based on Morrone 2006 schema); the previous records for Ecuador and Bolivia are erroneous (Martínez 1959).
The other three Eucraniini genera, Glyphoderus, Anomiopsoides, and Ennearabdus, were revised by Ocampo (2004Ocampo ( , 2005Ocampo ( , 2007Ocampo ( , 2010. The purpose of this contribution is to provide a taxonomic revision of the genus Eucranium including the description of one new species, to provide diagnosis and key to species, and to discuss their distribution, biology, and conservation status.

Materials and Methods
Specimens were examined, dissected, and illustrated using a dissecting stereomicroscope (10-40x). Mouth parts and male genitalia were dissected and cleaned in a dilute solution (~10%) of potassium hydroxide and neutralized in a dilute solution (~ 10%) of acetic acid. The male genitalia were placed in a glycerin-filled vial pinned under the specimen.
Body measurements, puncture density, puncture size, and density of setae were based on the following standards: Body length was measured from the middle of the anterior margin of the pronotum (at the middle) to the apex of the elytra, plus head length from the apex of clypeal process to the base of the head (head was measured separately because its variable position made it impractical to measure total body length). Body width was measured across mid-pronotum. Puncture density was considered "dense" if punctures were nearly confluent to less than 2 puncture diameters apart, "moderately dense" if punctures were 2-6 diameters apart, and "sparse" if punctures were separated by more than 6 diameters. Puncture size was defined as "small" if punctures were 0.02 mm or smaller, "moderate" if 0.02-0.07 mm, and "large" if 0.07 mm or larger. Setae were defined as "sparse" if there were few setae, "moderately dense" if the surface was visible but with many setae, and "dense" if the surface was not visible through the setae. Elytral carinae were counted from the elytral suture. Specimen labels were copied literally using "/" between lines and ";" between labels. sculptures. These characters rendered variable within species and were not reliable for species identification or description. In this work, new characters were explored and used to define species. Among these are Elytral pseudoepipleuron, pseudoepipleural angle with respect to elytral disc, elytral 8th striae (shape and sculpture), and shape and development of mesotibial spurs. Species male genitalia were studied in order to find species-specific patterns in the shape of the paremares, but the findings were not informative at this level. Internal sacs of paremeres were extracted and studied and these structures provided highly valuable information for phylogenetic analysis, however, they are impractical for species identification. Nevertheless, the information from the paremeres internal sacs is currently being used in a separate project on Eucraniini evolutionary biology (Ocampo et al in prep Gillet 1911: 983. Eucranium Brullé;Bruch 1911: 188. Eucranium Brullé;Blackwelder 1944: 197. Eucranium Brullé;Ocampo 2004Ocampo : 2555.
The genus Eucranium consists in six known species.
Supplementary distribution maps, locality data, and modeled distribution of E. arachnoides are provided at: http://www.biofinity.unl.edu

Phylogenetic relationships
Based on recently published phylogenetic analysis Hawks, 2006, Monahan et al. 2007) and a more comprehensive analysis based on molecular and morphological data including all known species in the tribe (Ocampo et al unpublished) the genus Eucranium constitutes a monophyletic group. In these analysis, Eucranium is the sister taxon to the monotypic genus Ennearabdus and a clade composed by Anomiopsoides + Glyphoderus. Evidence indicates that Eucranium and Ennearabdus diverged early from the Eucraniini common ancestor, and Anomiopsoides and Glyphoderus diverged from a more recent ancestor (Ocampo and Hawks, 2006, Ocampo unpublished data). "MUSEUM PARIS / D'ORBIGNY 1834"; "Anomiopsis / aelianus / Blanch"; "TYPE"; "Anomiopsis / aelianus Blanch / HOLOTYPE".
The type of Pachysoma lacordairei Laporte was not studied and it was nor possible to find it at MNHN where it should be deposited, this type is presumably lost.

Diagnosis
Males ( Figure 1) and females of Eucranium arachnoides can be distinguished from other Eucranium species by the following combination of characters: Elytron with pseudoepipleuron developed, pseudoepipleuron forming a <65° angle with elytral disc (Figures 1, 2); elytron with outer margin of 8th striae not carinated, if carinated, carinae poorly defined and never reflexed (specimens from western and southern Mendoza province). Mesotarsus longer than mesotibial spur; body size: length 18.4-30.4 mm.

Remarks
Based on morphological evidence it was concluded that there are no differences between E. pulvinatum Burmeister and E. arachnoides Brullé and these species are placed in synonymy.
Eucranium arachnoides is the species in the genus with the largest distributional range, and E. arachnoides presents considerable variation. Variation can be observed in the development of the pseudoepipleuron, body size, pronotal and elytral punctures, and male genitalia (slight differences in shape of parameres). These differences are not consistent among individuals of the same population. Based on the species concept used in this work to recognize Eucranium species, all these differences are attributed to intraspecific variation. Molecular information is needed to elucidate weather isolated populations (i.e., western Mendoza province, North Western Córdoba, and Eastern Buenos Aires) constitute independent evolutionary lineages and if they should be treated as different species.

Biology and conservation
Biology and behavior of this species were recently discussed by Zunino et al. (1989), Monteresino and Zunino (2003), Ocampo and Philips (2005), and Ocampo and Hawks (2006). This species has the largest distributional range among Eucranium species. Populations of this species generally have a small, patchy distribution and consequently susceptibly to local extinction if changes in the environmental conditions occur. The only known populations of E. arachnoides that are currently in a protected area are those from Reserva Natural Ñacuñán and Reserva Natural La Payunia in the Mendoza province.

Etymology
I take great pleasure in naming this species after my daughter Belén Victoria.

Biology and conservation
Specimens of E. belenae were observed carrying goat pellets and small pieces of dry horse dung at daylight hours (Video 1).
Nocturnal activity also has been observed for this species, although no foraging has been noticed at night (Ocampo and Philips 2005). This species occurs in sand dunes in northeastern Mendoza province, which includes Reserva Natural Telteca; this protected habitat (~32,000 has) contributes to the conservation of E. belenae (Figure 13).

Diagnosis
Males ( Figure 14) and females of E. cyclosoma can be recognized distinguished from other Eucranium species by the following combination of characters: Elytron with pseudoepipleuron not developed ( Figure  15); apex of mesotarsus reaches apex of outer mesotibial spur or not (viewed with tarsus extended parallel to tibial longitudinal axis) ( Figure 16); mesotibial outer spur distinctively broad at apical 1/2, asymmetrical ( Figure 16) (in some specimens this is character is not evident because the spur is worn down); elytral disc with interstriae smooth, evenly flat, 8 th stria not sulcate; northwestern Argentina; size 19.9-30.7 mm.

Biology and conservation
Specimens of E. cyclosoma were observed carrying small pieces of dry horse dung at daylight hours over sand dunes in Catamarca province (Video 2, Figure 18). Conservation status of this species has not been assessed. This species in not known to occur in any protected area.

Diagnosis
Males ( Figure 19) and females of E. dentifrons can be distinguished from other Eucranium species by the following combination of characters: Elytron with well defined pseudoepipleuron, pseudoepipleuron forming a 45-60° angle with elytral disc (Figures 19, 20); elytron with carina on outer margin of 8th stria, carina reflexed or rounded and reflexed; 7th interestria transversally rugose (most specimens), elytra with or without tubercles on humeral area; length 17.8-27.1 mm.

Remarks
Based on morphological evidence it was concluded that there are no differences between E. lepidum Burmiester and E. dentifrons (Guérin-Méneville) and so these species are placed in synonymy.
Eucranium dentifrons presents considerable variation in pronotal and elytral sculpture. Variation in puncture size and density on the pronotum and elytra is found among Figure 18. Habitat of E. cyclosoma close to Capillitas in Catamarca, Argentina. Figure 19. Eucranium dentifrons, male dorsal view. Figure 20. Eucranium dentifrons, elytron dorsolateral view. Figure 21. Habitat of Eucranium dentifrons in Península Valdes, Chubut, Argentina. High quality figures are available online.

18 20 21
specimens of the same population and among populations. Variation is also found in rugosity on elytral interval seven, been in most specimens obvious and in some specimens slightly evident (although always present). These differences are more obvious among specimens from Neuquén and western Río Negro province.

Biology and conservation
Specimens of E. dentifrons have been observed caring and provisioning their borrows with guanaco dung pellets and small pieces of dry horse dung at daylight over sand dunes in Península Valdez, Chubut, and in Chocón and near Las Lajas, Neuquén (personal observation) ( Figure 21).
Conservation status of this species has not been assessed. The only protected area where E. dentifrons is known to occur is Península Valdéz in Chubut province.

Remarks
Eucranium planicolle is the smallest species in the genus and exhibits less variation than do other species of Eucranium.

Diagnosis
Males ( Figure 24) and females of E. simplicifrons can be distinguished from other Eucranium species by the following combination of characters: Elytron with or without pseudoepipleuron, if present, pseudoepipleuron forming an <65° angle with elytral disc (Figures 24, 25); elytron with outer margin of 8th stria not carinated, if carinated, carina poorly defined and never reflexed; apex of mesotarsus when extended passes apex of outer mesotibial spur (viewed with tarsus extended parallel to tibial longitudinal axis) ( Figure 26); mesotibial outer spur slightly broader on apical 1/3, nearly symmetrical ( Figure 26); size, length 19.5-27.7 mm. Santiago del Estero.

Remarks
Eucranium simplicifrons is the rarest species in the genus in entomological collections, presumably because it occurs in areas relatively poorly collected.

Biology and conservation
With the exception that the species is diurnal (personal observation) nothing is known about the biology of E. simplicifrons. Conservation status of this species has not been assessed; the species does not occur in any protected area.

Biogeography and Conservation
Morphological divergence of Eucranium and known geographic distribution suggest that the genus constitutes an endemic taxon in Chaco and Monte biogeographic provinces. Biogeographically, the Monte and Chaco are interesting regions forming an extensive transitional zone between Neotropical and Andean biotas (Rundel et al. 2007;Morrone 2006). South American deserts constitute very old habitats as elucidates from the presence of many endemic suprageneric and generic taxa well adapted to arid conditions (Roig Juñent et al. 2001;Hawks 2006, Ocampo et al. 2010). In the Monte and Chaco, endemic, relictual taxa coexist with other endemic taxa that would have speciated in the area but with sister groups in neighbouring non-desert regions (ex. Aclopinae, Allidiostomatinae (Scarbaeidae), Taurocerastes (Geotrupidae). Thus, the Monte and Chacoan biota have multiple origins with most genera being from Neotropical origin followed by groups with Patagonian or Andean affinities.
Species of Eucranium are distributed across a ~2000 km long (North-South) and 500 km wide (East West) range. Nevertheless, species in this genus show little sympatry, E. arachnoides and E. planicolle partially share they distributional range, while the rest of the species, E. belenae, E. cyclosoma, E. dentifrons, and E. simplicifrons are isolated from other species in the genus or only share a few localities (ex. E. arachnoides and E. dentifrons in Río Negro province). Eucranium species have high endemicity and populations have patchy distributions that make them susceptibly to local extinction if changes in the environmental conditions occur. Nothing is known for Eucranium species' population dynamics or habitat conservation status. Only two species, E. belenae and E. dentifrons are distributed within natural reserves or protected areas. It is well documented that there are genetic implications for small population size, among these it is a decline of genomic variation resulting from allelic loss (O'Brien 1994). According to Meffe and Carrol (1997) for the long term viability of a population it is important for it to maintain genetic variability which would enable the population to adaptively tolerate changes in environmental conditions. Further more, Keller et al. (2004), based on a study of a flightless ground beetle, provided evidence that even abundant species can be seriously affected by habitat fragmentation. Considering that all species in the genus Eucranium are flightless, and consequently with limited expansion or migration abilities, they are mostly associated to fragile environments (such as sand dunes), in order to preserve these species it is critical to understand their population dynamics and their habitat conservation status. Eucranium is characterized by its unusual morphology and unique biology and behavior, and it constitutes an old evolutionary lineage. Vane-Wright et al. (1991) proposed that these characteristics would make the genus Eucranium of high conservation value.