Praocis (Mesopraocis) Flores & Pizarro-Araya, 2014

Flores, Gustavo E. & Pizarro-Araya, Jaime, 2022, Revision of the subgenus Mesopraocis Flores & Pizarro-Araya of the Neotropical genus Praocis Eschscholtz (Coleoptera, Tenebrionidae, Pimeliinae), ZooKeys 1100, pp. 29-55 : 29

publication ID	https://dx.doi.org/10.3897/zookeys.1100.78769
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scientific name	Praocis (Mesopraocis) Flores & Pizarro-Araya, 2014
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Subgenus Praocis (Mesopraocis) Flores & Pizarro-Araya, 2014

Praocis (Mesopraocis) Flores & Pizarro-Araya, 2014: 60. Type species: Praocis calderana Kulzer, 1958 (original designation).

Redescription.

Length 5.00-10.62 mm; habitus oval, convex; dorsal surface with short setae, ventral surface densely setose; pseudopleuron with long golden setae on upper surface, forming with the setae of the hypomeron a continuous row of long golden setae surrounding the body. Body, antennae, legs black, dark brown to light brown.

Head. Clypeal anterior margin concave, extended beyond epicanthus; frontoclypeal suture distinct, as a vertical groove, not covered by frons, clypeus and frons at same level; clypeus and frons with round punctures, epicanthus subquadrate (Fig. 1A View Figure 1 ). Antennae equal in length in both sexes; antennomere 10 wider than long; apical tomentose sensory patches on antennomeres 9 and 10 in two areas subequal in size, on antennomere 11 on distal third (Fig. 1B-D View Figure 1 ).

Thorax. Pronotum strongly convex, widest behind midpoint or at base, lacking carinae or striae; anterior margin concave, lacking carinate edge, width of anterior margin exceeding half the width of posterior margin; with lateral margins concave in anterior half and subparallel in posterior half (Fig. 4A-D View Figure 4 ); disc with sparse round punctures, each bearing a short, decumbent seta, visible at higher magnification (50 ×); punctures of disc smaller than punctures of elytron; prosternum horizontal, with carinate edge on anterior margin, broadened below gula (Fig. 1E View Figure 1 ); prosternal process subrectangular forming a straight angle, produced backwards, not reaching the midpoint of the space between pro, mesocoxae. Mesoventrite inclined forward, separated from prosternum (Fig. 1F View Figure 1 ). Hypomeron with shallow grooves not reaching lateral margin of pronotum, with a fringe of short or long golden setae below lateral margin of pronotum (Fig. 1E View Figure 1 ). Hypomeron with tubercles; mesepisternum and metepisternum with punctures. Metaventrite smooth on central area, with punctures on lateral thirds, and with two transverse grooves parallel to metacoxae (Fig. 1F View Figure 1 ). Metacoxal cavity closed laterally by metaventrite and abdominal ventrite 1.

Elytron convex, surface punctate, lacking carinae or striae, lateral margin not defined; pseudopleuron with a fringe of long golden setae on anterior half or entire upper surface (Fig. 1F View Figure 1 ), forming with the setae of the hypomeron a continuous fringe of long golden setae surrounding the body; epipleuron distinct, finely ridged throughout (Fig. 1F View Figure 1 ), gradually widening anteriorly, anterior quarter four times as wide as posterior half, anterior margin reaching elytral humeri and posterior angle of pronotum. Wingless, subelytral cavity sealed.

Legs. Distance between meso- metacoxae exceeding half mesocoxal length (Fig. 1F View Figure 1 ). Pro, mesofemora straight, metafemora curved inward. Femora with long, fine setae on anterior, posterior surfaces and dorsal fringe, abundant on pro, mesofemora, sparse on metafemora; ventral surface of profemora with a row of long setae on anterior edge. Protibiae explanate, apical process concave from behind (Fig. 2A View Figure 2 ), inner margin armed with a row of stout setae, outer margin concave; postero-distal, outer margins and posterior face with conical pegs sensilla type 1 (CP1) (Fig. 2A, B View Figure 2 ), antero-distal margin with conical pegs type 2 (CP2) (Fig. 2B View Figure 2 ), anterior and posterior faces (Fig. 2A, B View Figure 2 ) with long, fine setae (sensilla trichoidea) arising on punctures; posterior face of protibiae and inner, outer faces of meso, metatibiae with short, stout setae, arising on tubercles; meso, metatibiae with conical pegs type 1 on posterior face and type 2 on distal end. Pro, mesofemora longer than pro, mesotibiae; metafemora shorter than metatibiae; metatibiae straight. Tarsi bearing sparse decumbent setae on ventral surface; protarsomere 1 equal to combined length of tarsomeres 2-4, subequal to tarsomere 5 (Fig. 2B View Figure 2 ).

Abdomen. Ventrites 1-4 with sparse punctures each bearing a short seta; ventrite 5 with sparse punctures on central area separated by two to four puncture diameters, on lateral thirds separated by one to two puncture diameters. Male sternites VII and VIII emarginated.

Male terminalia and genitalia (Fig. 3A-D View Figure 3 ). Rods of spiculum gastrale V-shaped, joined at the apex. Dorsal membrane of proctiger concave, without sclerotized areas. Basal lamina of tegmen long (B/E> 1.0) (Fig. 3A, C View Figure 3 ). Lateral styles of tegmen distally close, with apex narrow, with setae on lateral margins (Fig. 3B, D View Figure 3 ), widest at base, and not overlapping median lobe dorsally. Median lobe tubulous, moderate (0.75 <L/T ≤ 1.00) and apex rounded (Fig. 3A, C View Figure 3 ).

Female terminalia and genitalia (Fig. 3E View Figure 3 ). Spiculum ventrale with arms short, “V” -shaped. Paraprocts long (2.0 <P/C ≤ 3.0), with setae; proctigeral baculus equal to length of paraproct baculus; apicodorsal lobe of proctiger extending about ½ length of coxite. 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 equal width throughout. Vagina saccate. Spermathecal accessory gland longer than vagina, with duct not annulate. Spermatheca with six basal tubes or less, all similar in length and branching pattern.

Geographic distribution.

Species of Praocis (Mesopraocis) are endemic to northern and central Chile and occur from 25° South (Paposo, Antofagasta Region) to 31° South (Caleta Limarí, Coquimbo Region) in the Atacama and Coquimban biogeographic provinces ( Morrone 2015) (Figs 5 View Figure 5 , 6 View Figure 6 ). Up to two sympatric species have been recorded together in the distribution area of the subgenus. But all four species can be sympatric with the remaining species (Figs 5 View Figure 5 , 6 View Figure 6 ) and there are no geographic barriers that separate species.

Habitat.

The distribution range of the subgenus extends from sea level to an altitude of ~1325 m. All Praocis (Mesopraocis) species are associated with coastal dunes stabilized with scattered vegetation and inland aeolian dunes located in the central valley (JPA pers. obs.) in the transitional coastal desert of Chile ( Cortés-Contreras et al. 2013; Flores and Pizarro-Araya 2014). Some species have been recorded in Pacific islands such as Choros, Damas, and Gaviota from the Choros Archipelago ( Alfaro et al. 2009). They are associated with shrubby and herbaceous vegetation (perennial and annual) characteristic of coastal dunes such as Nolana spp. ( Solanaceae ), Rhodophiala spp. ( Amaryllidaceae ), Leucocoryne spp. (Leucocoryneae), Cristaria spp. ( Malvaceae ).

Biology.

Adults have nocturnal habits, remaining buried in the sand during the day and appearing a short while after sunset (JPA pers. obs.), when sand surface cools down and night-moisture appears ( Koch 1961). Adults eat flowers and detritus of dune vegetation and larvae feed on tubers and roots of dune plants (JPA pers. obs.). Laboratory observations on oviposition: the females dig a depth ranging from 10 to 20 cm in the substrate and laid eggs individually or in groups of 3 to 5. The egg chorion is covered by a protective layer of mucilage to which sand grains adhere during oviposition. The resulting sand layer is thought to act as both a thermal insulator against the wide temperature oscillations that daily occur in these semiarid environments and as a mimicry strategy against edaphic predators, such as carabid larvae (e.g., Calosoma vagans Dejean), scorpions (e.g., Brachistosternus spp.), solpugids (e.g., Ammotrechelis spp., Mummucia spp.), and spiders (e.g., Lycinus spp.) (JPA pers. obs.).

Ecology.

In a taxonomic diversity study of epigean tenebrionids in the Choros Archipelago (Coquimbo Region), Praocis (Mesopraocis) pilula reached 5.9% of total abundance, with specimens recorded in coastal dunes of Choros, Damas, and Gaviota islands ( Alfaro et al. 2009). In other research conducted in Coastal Cordillera near Punta de Choros (Coquimbo Region), specimens of Praocis (Mesopraocis) pilula were caught in paleodunes stabilized with vegetation, making up 3.1% of the total catch ( Cortés-Contreras et al. 2013). Finally, Pizarro-Araya et al. (2012) performed a survey in continental dunes of Atacama Region and captured specimens of Praocis (Mesopraocis) calderana Kulzer, 1958 which were 2.8% of the total assemblage of terrestrial arthropods.