Taxonomic revision of the Peruvian genus Pilobaloderes Kulzer, 1958 (Coleoptera, Tenebrionidae, Pimeliinae, Praociini)

Abstract The monotypic genus Pilobaloderes Kulzer (Pimeliinae: Praociini), endemic to Peruvian Andes, is revised. Based on examination of recently collected specimens, we describe the female of the type species and a new species, Pilobaloderes aquilonarius sp. nov., emphasizing dimorphic and diagnostic characters of the protibiae. A redescription of the genus and its species, with remarks about sexual dimorphism are included. Habitus photographs, illustrations of protibiae, genital features, and a distribution map are also presented.


INTRODUCTION
The monotypic genus Pilobaloderes was proposed by Kulzer (1958) for a new species P. gebieni, described from a single male specimen collected in the Northern Peruvian Andes, and placed within the tribe Nycteliini (Tenebrionidae: Pimeliinae). Flores (2001) transferred this genus and Praocidia Fairmaire from Nycteliini to Praociini on the basis of new, constant tribal level characters (e.g. base of mandible twice as thick as the apex, prothorax semi-mobile and distance between meso-and metacoxae exceeding half mesocoxal length).
In recent years, we found six additional specimens of Pilobaloderes: two males and a female assigned to a new species, recovered from pitfall trapping samples, and two males and a female of P. gebieni, housed in Peruvian entomological collections. The objectives of this paper are to describe and illustrate a new species of Pilobaloderes, to describe the female of P. gebieni and to illustrate its female genitalia. As a result of these findings, the generic diagnosis of the genus is updated.
The present publication is registered in the ZooBank Life Science Identifier with the following LSID code: urn:lsid:zoobank. org:pub:21906DB3-3E8C-472D-8793-F9E243C078CF. Body length was measured dorsally, along the midline, from the anterior margin of the labrum to the apex of elytra. Terminology used in the descriptions follows Flores (2001) except that "frontal process" is replaced with epicanthus, "proepisternum" is replaced with hypomeron, and "mesosternum" with mesoventrite (Matthews et al. 2010); in protibiae "external process" is replaced with apical process (Doyen 1984: Fig. 41). Terminology and ratios of male genitalia were taken from Flores (1996), namely basal lamina of tegmen/lateral styles length (B/E) and median lobe/tegmen length (L/T). Terminology of female genitalia and ratio paraproct/coxite length (P/C) were those proposed by Doyen (1994). Following the suggestion of Kaminski et al. (2020) to assess homologies in the morphology of female genitalia, we used characters from a recent study of another genus of Praociini, Parapraocis (Flores & Giraldo 2020).
Label data from separate labels are given verbatim within square brackets and new lines on the same label are separated by a diagonal slash (/). Distribution map (Fig. 15) was prepared using SimpleMappr (Shorthouse 2010). For distribution of the species we used the biogeographic classification of Morrone (2014) and the ecosystems map of MINAM (2018).
Ventral surface of trochanters setose; setae on ventral femoral surface arising from tubercles.
Sexual dimorphism. Male protibiae with distal part curved inward, distal margin equal to 1/3 protibial length, with one spur, without apical process, distal part of inner margin concave, slender than proximal part, inner margin with fine setae, outer margin with short, stout setae, protarsomeres 2-4 as long as wide, tarsi with numerous setae on ventral surface (Figs. 7-8). Female protibiae straight throughout, with two spurs longer than in male, without apical process, distal part of inner margin straight, with fine and stout setae, outer margin with stout setae longer than in male, protarsomeres 2-4 wider than long; tarsi with sparse setae on ventral surface (Fig. 9).
Male genitalia (Figs. 10-13). Rods of abdominal sternum IX close at basal third, not inclined dorsally at base. Dorsal membrane of proctiger concave, with two sclerotized areas. Basal lamina of tegmen long (B/E > 1.0). Lateral styles of tegmen distally close, apex narrow, widest at base, with setae on lateral margin and with a subapical tuft of setae on ventral surface. Median lobe moderate (0.75 < L/T ≤ 1.00), sheathshaped, a half width of lateral styles of tegmen.
Female genitalia (P. gebieni; Fig. 14). Spiculum with arms "V"-shaped. Paraprocts glabrous; coxites with setae, divided into two visible lobes: the basal lobe bears oblique baculi and the apical lobe is composed of the fully fused second, third and fourth lobes, which bears lateral gonostyli, basal lobe of coxite not extended over paraproct, separated from the apical lobe by a transverse pleat and shorter than the apical lobe; midventral sclerite distally broadened. Paraprocts long (2.0 < P/C ≤ 3.0); proctigeral baculus shorter than paraproct baculus; apicodorsal lobe of proctiger extending about ½ length of coxite. Vagina saccate. Spermathecal accesory gland longer than vagina, with duct not annulate. Spermatheca with two basal tubes as long as vagina, all similar in length, and unbranched.
Distribution. Known from the type locality at Otuzco province (2100 m) and also from Cajatambo province (2254 m), in Andean scrub of the northern and central Peruvian Andes (MINAM 2018) (Fig. 15).
Etymology. The specific epithet is a Latin adjective meaning northern, referring to the fact that this species represents the northernmost distribution of the genus.

DISCUSSION
The genus Pilobaloderes is an interesting Peruvian endemic, whose scarce number of known specimens stems from both apparently small populations and scarce collection efforts in Andean ecosystems. Together with Pilobaloderes, the genera Platyholmus and  Kulzer (1958) noted the remarkable distally inward-curved protibiae in the holotype male of Pilobaloderes gebieni and the lack of an apical process, with only one apical spur (Flores 2001: Fig. 6). These features are unique among genera of Praociini (Flores 2001) and are also confirmed in the males examined here, the holotype of the new species P. aquilonarius (Fig. 8) and two males of P. gebieni (Fig. 7).
In this study we examined for the first time female specimens of Pilobaloderes and we found that there are many features in protibiae indicating sexual dimorphism . In females the protibia has two apical spurs as well as in males and females of remaining genera of Praociini; curvature and fine setae on internal surface in protibiae are exclusive to males (Figs. 7-8) while female specimens have protibiae straight with fine and stout setae (Fig. 9). Additionally, there are also differences between both sexes in protarsomeres 2-4 and setae on ventral surface of all tarsi: male with protarsomeres 2-4 as long as wide, tarsi with numerous setae on ventral surface (Figs. 7-8); female with protarsomeres 2-4 wider than long, tarsi with sparse setae on ventral surface (Fig. 9).
Pilobaloderes aquilonarius sp. nov. differs from P. gebieni by having the clypeus with a U-shaped anterior margin, epicanthus rounded ( Fig. 4), epipleuron glabrous, pseudopleuron with setae arising from large tubercles twice than diameter of each seta, ventral femoral surface with sparse setae (Fig. 6), male protibiae with distal half of inner margin concave, with a row of setae on dorsal margin and remaining internal surface glabrous (Fig. 8), while Pilobaloderes gebieni has the clypeus with a concave anterior margin, epicanthus subquadrate (Fig. 3), epipleuron setose, pseudopleuron with setae arising from small tubercles the same size as the diameter of each seta, ventral femoral surface densely setose (Fig. 5), male protibiae with distal third of inner margin concave and internal surface velvet-like (Fig. 7).