The genus Pilobalia Burmeister 1875 in Peru: updated checklist and distribution records (Coleoptera: Tenebrionidae: Pimeliinae: Nycteliini)

: Pilobalia (Pimeliinae: Nycteliini) is an endemic genus of the Andean region of South America, distributed in Peru, Bolivia, Chile and Argentina. e objective of this work was to update the knowledge of the genus in the Peruvian territory, providing an updated checklist of species and new distribution records. From examination of around 580 specimens, a total of 26 species and two subspecies of Pilobalia are recorded for Peru, incorporating two that were not previously recorded, P. decorata immaculata (Blanchard) and P. oblonga (Blanchard). Also distribution maps and comments about its distribution patterns are provided.

and listing the species known at that date.Fairmaire (1876;1878;1902;1903) added five species and Gebien (1936) designated Pilobalia decorata (Erichson, 1834) as type species of the genus.In his revision of the Nycteliini tribe, Kulzer (1954) reviewed the genus, described twenty species, assigned subspecies rank to Pilobalia immaculata (Blanchard, 1843) and presented a key for all species known until then.Subsequent contributions of Kulzer (1955Kulzer ( , 1958Kulzer ( , 1959) ) added seven species and assigned subspecies rank to Pilobalia murina Kulzer, 1954. Later, Molinari (1968) and Peña (1973) described four and five species respectively, all of them from Argentina.More recently, Ferru & Pizarro-Araya (2007) offered the first Chilean records of Pilobalia torresi Molinari, 1968 andPilobalia escobari Peña, 1973 based on specimens collected in the Altiplano of Tarapaca Region, including morphological redescriptions and environmental characterization of collection sites.
Within the tenebrionid fauna of Peru, the genus Pilobalia is currently represented by 25 species and one subspecies, with a high rate of endemism (about 96%) and with an imprecise number of undescribed species observed in collecting trips and entomological collections (Smith et al., 2015;Giraldo & Flores, 2016).Most of its species are distributed in Andean environments, including western Andean ranges (1000 m -3800 m), inter-Andean valleys (1500m -3300 m) and high plateaus or "Puna" (3800 m -5000 m) (Giraldo & Flores, 2016) (Fig. 1a).Available published records account for its presence in particular habitats such as "lomas" vegetation in coastal desert (Aguilar, 1976), quinoa and potato crops (Escalante et al., 1981;Rasmussen et al., 2003) and high Andean Polylepis forests (Rossi et al., 2018).
e purpose of the present work is to update the knowledge of the genus Pilobalia, providing an updated checklist of Pilobalia species and new distribution records in Peruvian territory.
e checklist includes distribution status (endemic or new record), synonymy, type specimens examined (directly or indirectly), type localities (incorrectly spelled in quotation marks, doubtful with a question mark) and material examined, as available for each species.e distribution records of specimens that were not assigned to described species due to their poor condition, doubtful resemblance to known species, or preliminary assignment to undescribed species were summarized in a table indicating regions and provinces according to Peruvian territorial jurisdictions, number of specimens found for each of them, as well as geographic coordinates and altitude data.Overall, type and non-type localities were employed to plot distribution maps for the genus in Peru.e frequency of distribution records according to its latitude and altitude were plotted with histograms and their patterns were interpreted taking into account habitat selection of genus and collecting effort performed in Peruvian territory.
Type locality: Cajamarca (Cajabamba 4000 m).According to the updated checklist presented here, the genus Pilobalia in Peru is now represented by 26 species and two subspecies.It has been possible to examine type specimens of eleven species, which represents a 39% of the recorded species and subspecies in Peru.In the Peruvian collections, specimens corresponding to 10 species and two subspecies were found, namely P. alboscripta, P. blancasi, P. crassicornis, P. crassicosta, P. decorata decorata, P. decorata immaculata, P. decorata titschacki, P. michelbacheri, P. oblonga, P. ruficollis, P. unicolor and P. weyrauchi.Otherwise, sixteen species are currently known only from their type specimens and are not properly represented in Peruvian collections.Among these species with poorly known distribution, P. baeri, P. becki, P. eyi, P. gracilipes, P. löffleri, P. oberthüri, P. ornata, P. philippi, P. subnuda, P. tenella, P. tristis and P. voogdi have more or less welldefined type localities, so their distributions must be restricted and hitherto overlooked by collecting surveys in Peru.For P. haagi, P. lineata and P. soror, the label data of type specimens only indicates "Peru" without further details, so its precise distribution will only be defined with more collecting effort.e status of P. dorsoplicata is even more uncertain following notes by Kulzer (1954), with a type specimen extensively damaged and bearing label data "Peru", so this species should be declared nomen dubium according to International Code of Zoological Nomenclature.
Distribution records of undetermined specimens of genus Pilobalia are presented in Table I. ese records include 275 specimens from 15 regions and 41 provinces of the Peruvian territory.A high number of specimens not reliably assigned to described species is not surprising for a genus of wingless darkling beetles prone to speciation by vicariant orographic barriers and this biological trait partly explains why its systematics studies are still in progress.
Table I.Distribution records of undetermined specimens of the genus Pilobalia arranged in regions and provinces of Peruvian territory.Specimen numbers in parentheses.Geographic coordinates in decimal degrees and altitude in meters Taking into account all the available distribution records, distribution maps were elaborated, including 240 localities (Fig. 1).ese records place the northern limit of the Nycteliini tribe to around 6°S, some 7°f urther north than on the map presented by Flores & Triplehorn (2002).As expected according to previous works (Peña 1973, Giraldo & Flores 2016), records are mostly located along the different altitude levels of the Andes mountain range, with very few to the west (coastal desert) and east (tropical forests) of the Andes.e records in the coastal desert are located between 12-13°S, these correspond specifically to Pilobalia blancasi collected in patches of fog-dependent vegetation called "lomas", as documented in early works by Aguilar (1976) and by the specimens found in the collections.e label data of some specimens suggest that they were collected in tropical areas between 5-13°S, from 150 to 2200 meters of altitude.At first glance, tropical areas do not have suitable habitats for the genus, however the presence of semi-arid patches or dry micro-habitats cannot be ruled out, which should be verified with a greater collection effort in these places.
e histogram plot of latitude data shows higher frequencies (0.57) for southern latitudes from 12°30'0" S (Fig. 4a).is pattern could be explained by the fact that the Southern Peruvian Andes have a wider area, mostly covered with highland grasslands, which are also easier places for collecting, using a combination of pitfall trapping and direct searching under rocks.e histogram plot of altitude data shows higher frequencies (0.76) for altitudes above 3000 m (Fig. 4b).is means that the genus Pilobalia would have largest populations and species number inhabiting highland plains and interandean valleys, while ravines covered with cacti and shrubs at lower altitudes would be secondary habitats.Also, as stated above, collecting is easier in larger areas and more difficult in narrow places, where populations could also be smaller.