Towards a revision of the South American genus Praocis Eschscholtz (Coleoptera, Tenebrionidae), with estimation of the diversity of each subgenus

Abstract A review of the subgenera of the South American genus Praocis Eschscholtz (Pimeliinae: Praociini) is presented. Praocis comprises 77 species and 8 subspecies arranged in nine subgenera distributed in arid lands from Central Peru and Bolivia to the Southern part of Patagonia in Chile and Argentina. For each subgenus of Praocis: Praocis Eschscholtz, Mesopraocis Flores & Pizarro-Araya, subgen. n., Anthrasomus Guérin-Méneville, Filotarsus Gay & Solier, Postpraocis Flores & Pizarro-Araya, subgen. n., Hemipraocis Flores & Pizarro-Araya, subgen. n., Orthogonoderes Gay & Solier, Praonoda Flores & Pizarro-Araya, subgen. n., and Praocida Flores & Pizarro-Araya, subgen. n., we present a diagnosis using new and constant characters of adult morphology such as clypeal configuration, length and proportion of antennomeres 9, 10 and 11, arrangement of apical tomentose sensory patches on antennomeres 10 and 11, anterior margin of prosternum, lateral margin of elytron, ventral surface of profemora, and shape of protibiae. An identification key for the nine subgenera of Praocis is presented. Type species are designated for the five new subgenera; for Mesopraocis: Praocis calderana Kulzer, for Postpraocis: Praocis pentachorda Burmeister, for Hemipraocis: Praocis sellata Berg, for Praonoda: Praocis bicarinata Burmeister, for Praocida: Praocis zischkai Kulzer, and for the previously described subgenus Orthogonoderes: Praocis subreticulata Gay & Solier. The current number of species and the estimated number of species to be described are presented. The distribution ranges of the subgenera, including new records from collections and recent expeditions, are given. Habitat preferences and a discussion of the biogeography of the genus are also presented.


Introduction
The genus Praocis Eschscholtz belongs to the Praociini, an endemic Neotropical tribe of Pimeliinae with 151 species arranged in 15 genera (Flores and Pizarro-Araya 2012). Praocis is the most specious genus of the tribe (52% of the species). It comprises 77 species and 8 subspecies, arranged in nine subgenera (Flores and Pizarro-Araya 2012), distributed from central Peru to the southern part of Patagonia in Argentina and Chile. The distribution of Praocis species coincides with the whole distribution of the tribe (Fig. 1) and is related to the arrangement of the Andes mountain range in arid and semiarid lands of southern South America (Flores and Pizarro-Araya 2006).
The last revision of Praocis was made by Kulzer (1958) in the context of a tribal review. Kulzer (1958) classified the species of Praocis into 10 subgenera, six of which were new: Mesopraocis, Postpraocis, Parapraocis, Hemipraocis, Praonoda, and Praocida, plus the four previously recognized as valid by Solier (1840): Praocis s. str., Anthrasomus Guérin-Méneville 1834, Orthogonoderes Gay & Solier, 1840, and Filotarsus Gay & Solier, 1840. Kulzer (1958 did not characterize his new subgenera nor designate type species, but in his key he mentioned character states for identifying some of them except between Anthrasomus and Filotarsus, and between Orthogonoderes and Praocida, which can be keyed only by body size. Kulzer (1958) also failed to assess the geographic distribution of the subgenera, reporting only isolated localities of the species.
The subgeneric classification of the genus was recently reviewed (Flores and Pizarro-Araya 2012) and the genus was redefined on the basis of five constant character states. The subgenus Parapraocis was excluded from Praocis because its species exhibit different character states from those defining the genus and it was recognized as a separate genus within Praociini (Flores and Pizarro-Araya 2012).
In the current study we report new constant characters to define each Praocis subgenus, such as shape of clypeus, frons and clypeal suture, length and proportion of antennomeres 9, 10 and 11, arrangement of apical tomentose sensory patches on antennomeres 10 and 11, and ventral surface of profemora. We also used the characters defined by Kulzer: shape of anterior margin of prosternum, posterior angles of pronotum, lateral margin of pronotum, lateral margin of elytron, shape of body and apical process of protibiae.
The objectives of this study are to present elements for a revision of the genus Praocis by incorporating new constant characters from external morphology to define each subgenus, to designate type species for some subgenera that remain unavailable, to estimate the diversity of each subgenus, to detail the geographic distribution and habitat of each subgenus and to report new distributional records for some subgenera.

Material and methods
Material examined. The present study is based on an examination of specimens deposited in the following collections (we follow Arnett et al. 1993  The remaining five names of the subgenera proposed by Kulzer (1958): Mesopraocis, Postpraocis, Hemipraocis, Praonoda, and Praocida are unavailable because Kulzer (1958) did not designate type species for these subgenera. To be available, every new genus-group name published after 1930 must, in addition to satisfying the provisions of Article 13.1 (ICZN 1999), be accompanied by the fixation of a type species in the original publication (Article 67.4.1 ICZN 1999). These five names will be made available for the first time in this article. To fix the current interpretation of these names and to ensure stability as these names were used in previous works (Peña 1966;Flores 2007Flores , 2009Alfaro et al. 2009;Flores et al. 2011;Flores and Pizarro-Araya 2012;Cortés-Contreras et al. 2013), we use the same names proposed by Kulzer (1958), present a diagnosis of each subgenus and hereby designate the type species on the basis of the specific names available for this nomenclatural act, the type specimens are not lost and the species is representative of the characters of the subgenus.
Characters. For each subgenus of Praocis we present a diagnosis using the following characters and character states: Clypeal configuration (characters 1-3). The anterior margin of clypeus, in most subgenera, extends beyond the lateral expansion of frons (Fig. 3); in some species of Filotarsus it appears at same level as lateral expansion of frons. The width of the anterior margin of the clypeus, in most subgenera, does not exceed half the interocular width ( Fig. 3), while in some species of Filotarsus it is equal to interocular width. The clypeal suture shows two different states: as horizontal groove (Fig. 4), the clypeus being lower than frons; and as vertical groove, in this state the clypeus and frons are at the same level (Fig. 3).
Arrangement of apical tomentose sensory patches on antennomeres 10 and 11 (characters 6-7) are also variable among the subgenera. The apical tomentose sensory patches on antennomere 10 are arranged in two areas subequal in size (Fig. 6), or in a dorsally continuous semicircle (Fig. 5). On antennomere 11, the apical tomentose sensory patches are located in a single area on the distal third ( Fig. 6) or on the distal half of its surface (Fig. 5).
The anterior margin of the prosternum (character 8) presents two states: with a narrow sharp edge or lacking that edge. The lateral margin of the elytron (character 9) can be not defined, rounded, continuous between dorsal area of elytron and pseudopleuron, or well defined by a narrow, sharp carina-shaped edge or by a wide longitudinal, prominent edge. The ventral surface of the profemora (character 10) presents a row of setae on the anterior edge or lacks that row of setae. The shape of protibiae (character 11) varies between explanate, distal margin width exceeding 1/3 of protibial length, and not explanate, distal margin width equal to 1/4 of protibial length.
Distribution. With the distributional data published (Kulzer 1958;Peña 1966;Ferrú and Elgueta 2011;Flores and Pizarro-Araya 2012) and from specimens deposited in the examined collections we made approximate maps of the current geographic distribution for each subgenus. New records are reported for some subgenera and enlargement of their distribution. As a result of recent expeditions (Alfaro et al. 2009;Flores et al. 2011) we recorded the subgenera present on Pacific islands and Peninsula Valdés in the Atlantic Ocean. For distribution of the species we used the biogeographic classification by Morrone (2006).
Estimation of the diversity of each subgenus. Based on the types of known species (deposited at FMNH, MACN, MLPA, MNHUB, MNHN, MNNC, and NHMB) and the keys of Kulzer (1958), all specimens available in collections were determined and we identified specimens belonging to species to be described. Other unnamed species were found in collecting trips made for our projects in IADIZA and LEULS since 2001 until now. A list of the unnamed species by subgenus was made with these records and the diversity of each subgenus and of the whole genus was estimated, including the species to be described.
Species list. Based on the last revision of the genus (Kulzer 1958) and on most recent studies of types and new synonymies (Flores 2007(Flores , 2009Pizarro-Araya 2010, 2012;Flores et al. 2011), we made a list of species included for each subgenus. Some species were described after Kulzer`s revision (Kaszab 1964(Kaszab , 1969Molinari 1969;Marcuzzi 1977Marcuzzi , 2001 or rediscovered (Flores 2007), so we assigned these species to some subgenus according to the diagnostic characters presented here.

Results
Genus Praocis Eschscholtz, 1829 http://species-id.net/wiki/Praocis Generic characteristics. The species of Praocis can be recognized by having maxillary palps with last segment axe-shaped (apex twice as wide as base), antennomere 3 shorter than 4 + 5 combined, pronotum with anterior margin concave, width of posterior margin exceeding width of anterior margin, single lateral margin slender, expanded, remote from disc, and anterior angles rounded; mesosternum inclined forward, separated from prosternum; elytron with punctuate surface; apterous.
Diagnosis. Clypeus with anterior margin extending beyond to lateral expansion of frons, width of anterior margin not exceeding half the interocular width, clypeal suture as a vertical groove, not covered by frons, clypeus and frons at same level; antennomere 10 wider than long, antennomere 9 longer than antennomere 10, antennomere 11 longer than antennomere 10; apical tomentose sensory patches on antennomere 10 in a dorsally continuous semicircle, on antennomere 11 on distal half; prosternum with a narrow edge on anterior margin; lateral margin of elytron well defined; ventral surface of profemora with a row of setae on anterior edge; protibiae explanate.
Diversity. This subgenus contains 18 species of which 2 species were recently described (Flores and Pizarro-Araya 2012), increasing 13 percent the number of species ( Fig. 33).
Habitat. The distribution range of the subgenus extends from sea level to an altitude of ~1300 m. Most species are distributed between the Huasco coastal desert and the coastal shrub steppe (Gajardo 1994), with 4 and 10 species each, and are ecologically related to shrub and herbaceous vegetation (perennial and annual) characteristic of the Chilean Coastal Desert (CCD), in sandy soils or clayey, poorly-permeable soils (Flores and Pizarro-Araya 2012;Cortés-Contreras et al. 2013; collection data FMNH, IADIZA, LEULS, and pers. obs.). One species (Praocis (P.) costata Solier) inhabits deciduous woodlands of Nothofagus spp. (Gajardo 1994) in the Valdivian Forest biogeographic province (Morrone 2006) (Fig. 16 Kulzer, 1958, present designation. Diagnosis. Clypeus with anterior margin extending beyond to lateral expansion of frons, width of anterior margin not exceeding half the interocular width, clypeal suture as a vertical groove, not covered by frons, clypeus and frons at same level; antennomere 10 wider than long, antennomere 9 of equal length to 10, antennomere 11 of equal length to 10; apical tomentose sensory patches on antennomere 10 in two areas subequal in size, on antennomere 11 on distal third; prosternum with a narrow edge on anterior margin; lateral margin of elytron not defined; ventral surface of profemora with a row of setae on anterior edge, protibiae very explanate. Distribution. Species of Praocis (Mesopraocis) are endemic to northern Chile and occur from 25°South (Paposo, Antofagasta Region) to 31°South (Caleta Limarí, Coquimbo Region) in the biogeographic provinces of Atacama and Coquimbo (Morrone 2006) (Fig. 17).
Diversity. This subgenus contains 4 species (Kulzer 1958) plus 1 species to be described, 5 species in total, with a 25 percent increase in the number of species (Fig. 33).
Habitat. The distribution range of the subgenus extends from sea level to an altitude of ~1325 m. All Mesopraocis species are associated with coastal dunes stabilized with vegetation or paleodunes in the transitional coastal desert of Chile and have nocturnal habits, remaining during the day under stones or plants (Cortés-Contreras et al. 2013, collection data FMNH, IADIZA, LEULS, MNNC, and pers. obs.) (Fig. 18).
Diversity. This subgenus contains 7 species/subspecies (Kulzer 1958;Flores 2007Flores , 2009) plus 3 species to be described, 10 species in total, with a 43 percent increase in the number of species (Fig. 33).
Habitat. Species of Praocis (Postpraocis) have diurnal habits, remaining during the night under stones or plants. In central Chile they can be observed walking on coastal plains or in sandy places lying from sea level to an altitude of ~1300 m. In Argentina, northern Chile and Bolivia, they occur from 1600 m in high altitudinal valleys associated with the Andes mountain range to an altitude of 4200 m in the high Puna plateau, in sandy soils or clayey, poorly permeable soils (Ferrú and Elgueta 2011;Cortés-Contreras et al. 2013; collection data FMNH, IADIZA, LEULS, and pers. obs.) (Fig. 20) Diagnosis. Clypeus with anterior margin extending beyond to lateral expansion of frons, width of anterior margin not exceeding half the interocular width, clypeal suture as a horizontal groove covered by frons, clypeus lower than frons; antennomere 10 wider than long, antennomere 9 longer than antennomere 10, antennomere 11 longer than antennomere 10; apical tomentose sensory patches on antennomere 10 in two areas subequal in size, on antennomere 11 on distal half; prosternum with a narrow edge on anterior margin; lateral margin of elytron not defined; ventral surface of profemora without a row of setae on anterior edge, protibiae not explanate.
Diversity. This subgenus contains 5 species/subspecies (Kulzer 1958;Flores 2007) plus 1 species to be described, 6 species in total, with a 20 percent increase in the number of species (Fig. 33).
Habitat. Species of Praocis (Anthrasomus) have nocturnal habits, remaining during the day under stones or plants in coastal plains, gullies, and transverse valleys in semiarid Chile. They occur from sea level to an altitude of 2800 m, in stony-clayey, poorly permeable soils (collection data FMNH, IADIZA, LEULS, and pers. obs.) (Fig. 22)  Diagnosis. Clypeus with anterior margin extending beyond to lateral expansion of frons or at same level as lateral expansion of frons, width of anterior margin not exceeding half the interocular width or width of anterior margin same as interocular width, clypeal suture as a vertical groove, not covered by frons, clypeus and frons at same level or clypeal suture as a horizontal groove not covered by frons, clypeus lower than frons; antennomere 9 longer than antennomere 10, antennomere 11 longer than antennomere 10; apical tomentose sensory patches on antennomere 10 in a dorsally continuous semicircle, on antennomere 11 on distal half; prosternum with a narrow edge on anterior margin; lateral margin of elytron not defined; ventral surface of profemora without a row of setae on anterior edge, protibiae explanate.
New records. We present a new record for the Peninsula Valdés in Argentina (Flores et al. 2011).
Habitat. Species of Praocis (Hemipraocis) have diurnal and crepuscular habits, hiding during the night under shrubs, stones or buried in sand. They inhabit the Patagonian steppes and coastal Pampa from sea level to an altitude of 1700 m, in sandy soils or clayey, poorly permeable soils (Flores et al. 2011; collection data FMNH, IADIZA, and pers. obs.) (Fig. 26).
Diversity. This subgenus contains 2 species (Kulzer 1958) plus 2 species to be described, 4 species in total, with a 100 percent increase in the number of species (Fig. 33).
Habitat. Species of Praocis (Praonoda) have diurnal and crepuscular habits, hiding during the night under shrubs or stones. They inhabit the Patagonian steppes from sea level to an altitude of 1250 m, in sandy soils or clayey, poorly permeable soils (collection data FMNH, IADIZA and pers. obs.) (Fig. 28).

Type species.
Praocis subreticulata Gay & Solier in Solier, 1840, present designation. Diagnosis. Clypeus with anterior margin extending beyond to lateral expansion of frons, width of anterior margin not exceeding half the interocular width, clypeal suture as a horizontal groove covered by frons, clypeus lower than frons; antennomere 9 longer than antennomere 10, antennomere 11 shorter than antennomere 10; apical tomentose sensory patches on antennomere 10 in two areas subequal in size, on antennomere 11 on distal third; prosternum without a narrow edge on anterior margin; lateral margin of elytron well defined; ventral surface of profemora without a row of setae on anterior edge, protibiae explanate.
New records. We present a new record of Praocis argentina Kulzer for the Atlantic coast in Argentina, the isthmus of Peninsula Valdés, 42°30'S.
Diversity. This subgenus contains 23 species (Kulzer 1958;Flores 2007Flores , 2009) plus 10 species to be described, 33 species in total, with a 43 percent increase in the number of species (Fig. 33).
Habitat. Species of Praocis (Orthogonoderes) have diurnal and crepuscular habits, hiding during the night under shrubs or stones. In central Chile they can be observed in coastal dunes stabilized with vegetation or paleodunes, gullies, coastal plains, transverse valleys and Coastal and Andean mountain ranges from sea level to an altitude of 2700 m. In Argentina, Bolivia, Peru, and northern Chile, they occur from 1600 m high altitudinal valleys associated with the Andes mountain range to an altitude of 4200 m in the high Puna plateau, in sandy soils or in clayey, poorly permeable soils (Cortés-Contreras et al. 2013; collection data FMNH, IADIZA, LEULS, and pers. obs). The only species inhabiting Patagonian steppes, Praocis (Orthogonoderes) argentina, is recorded from 1700 m in southern Mendoza to sea level on the Atlantic coast in Argentina (collection data IADIZA, LEULS, and pers. obs.). Orthogonoderes is the only subgenus inhabiting both the Pacific and Atlantic coasts of South America (Fig. 30).  Kulzer, 1958;Praocis penai Kulzer, 1958(incorrect original spelling: peñai, Article 32.5 ICZN 1999; Praocis chilensis (Gray, 1832); Praocis insularis Kulzer, 1958;Praocis tibiella Kulzer, 1958;Praocis argentina Kulzer, 1962; Praocis magnoi Molinari, 1969.  Diagnosis. Clypeus with anterior margin extending beyond to lateral expansion of frons, width of anterior margin not exceeding half the interocular width, clypeal suture as a horizontal groove not covered by frons, clypeus lower than frons; antennomere 9 longer than antennomere 10, antennomere 11 longer than antennomere 10; apical tomentose sensory patches on antennomere 10 in two areas subequal in size, on antennomere 11 on distal third; prosternum without a narrow edge on anterior margin; lateral margin of elytron well defined; ventral surface of profemora without a row of setae on anterior edge, protibiae explanate.

Species included. Praocis cribrata
Distribution. Species of Praocis (Praocida) inhabit southern Peru, central and southern Bolivia and northern Argentina. They occur from 12°South (Cuzco, Peru) to 31°South in Cordoba (northern Argentina), in the biogeographic provinces of Puna, Chaco, and Pampa (Morrone 2006) (Fig. 31). Praocida is the only subgenus of Praocis inhabiting the biogeographic province of Chaco.
New records. We present a new record of Praocis (Praocida) teniucosta Kulzer for the mountains in South Buenos Aires province (38°S).
Diversity. This subgenus contains 4 species (Kulzer 1958;Flores 2009) plus 3 species to be described, 7 species in total, with a 75 percent increase in number of species (Fig. 33).
Habitat. Species of Praocis (Praocida) have nocturnal habits, hiding during the day under shrubs, stones or logs in clayey, poorly permeable soils. They occur from 1200 m in the Chacoan forest to an altitude of 4000 m in Puna (collection data FMNH, IADIZA and pers. obs.) (Fig. 32).

Estimation of the diversity of the whole genus
Praocis currently contains 77 species and 8 subspecies (Flores and Pizarro-Araya 2012) arranged in 9 subgenera (Fig. 33). Taking into account the 34 currently undescribed species, the genus will have 119 species/subspecies (Fig. 33), with a 47 percent increase in the number of species in the entire genus. All these undescribed species fall within the present generic concept of Praocis. An assessment of the subgeneric characters presented herein among these species to be described show a preliminary affiliation as detailed in Fig. 33. Three species that did not fit in any generic concept of Praociini or subgeneric concept of Praocis were recently described in a new genus, Patagonopraocis (Flores and Chani-Posse 2005).

Character states
A table was made with the character states used in the diagnoses (Table 1). This table summarizes the distribution of character states among the subgenera. It can be observed that each subgenus can be defined by a particular combination of these characters, stated in each diagnosis. For the characters here named 1-3, different species of Filotarsus present both the states found for each character, which are constant and well defined in all the species of the other subgenera, suggesting that in Filotarsus there are at least two groups of species which will be elucidated further by examining all the species of the subgenus and conducting a cladistic analysis of the group. Some character states appear as unique for some subgenera such as antennomere 11 of equal length to 10 in Mesopraocis and antennomere 11 shorter than antennomere 10 in Orthogonoderes. One third of the characters analysed here are from the antennae, suggesting the importance of studying the length and proportion of antennomeres 9, 10 and 11 and the arrangement of the apical tomentose sensory patches on antennomeres 9, 10 and 11. Using these character states, we presented a preliminary identification key for the subgenera of Praocis.

Biogeography
The distribution of the whole genus Praocis is related to the arrangement of the Andes mountain range in southern South America. The Andes are the only high mountain chain in the continent, running along the Pacific coast of South America from Venezuela down South to Tierra del Fuego, extending over 8500 km and separating xeric habitats both eastward and westward (Flores and Pizarro-Araya 2006). Among the genera of Pimeliinae, the distributional patterns of the nine subgenera of Praocis were analysed in relation to the Andes mountain range. We found three distribution Table 1. Characters studied and distribution of character states among the subgenera of Praocis.  (Figs 15, 17, 21); three endemic subgenera east of the Andes, in Patagonian steppes, Monte, Chaco and eastern Puna (Argentina, Bolivia and Peru), Hemipraocis, Praonoda and Praocida (Figs 25,27,31); and three subgenera widely distributed on both sides of the Andes and inhabiting also high altitudes of the Andes, Postpraocis, Filotarsus and Orthogonoderes (Figs 19, 23, 29). Based on these distribution patterns, and despite the current lack of a phylogeny for the genus, we can hypothesize that the ancestor of all Praocis species was older than the uplift of these mountains and the distribution of the species of six current subgenera was affected by a vicariant event caused by the uplift of the Andes. This vicariant event, which was analyzed in known phylogenies of tribes and genera of Pimeliinae in South America, left genera and species both east and west of the Andes (Flores and Pizarro-Araya 2006).