Research Article |
Corresponding author: Gustavo E. Flores ( gflores@mendoza-conicet.gob.ar ) Academic editor: Patrice Bouchard
© 2022 Gustavo E. Flores, Jaime Pizarro-Araya.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Flores GE, Pizarro-Araya J (2022) Revision of the subgenus Mesopraocis Flores & Pizarro-Araya of the Neotropical genus Praocis Eschscholtz (Coleoptera, Tenebrionidae, Pimeliinae). ZooKeys 1100: 29-55. https://doi.org/10.3897/zookeys.1100.78769
|
The second part of a revision of the species of the genus Praocis Eschscholtz is presented. The subgenus Mesopraocis Flores & Pizarro-Araya, distributed in northern Chile from 25° South to 31° South, is revised. This article includes a redescription of the subgenus, redescriptions of its species, an identification key, and a discussion on morphological adaptations of the species to fossorial life. Habitus photographs, scanning electron micrographs of head, antennae, prosternum, abdomen, and protibiae, illustrations of genital features, and distribution maps are presented. Conical pegs sensilla on tibiae are described and illustrated using SEM for the first time for a South American tenebrionid species. A new Praocis species is described: Praocis (Mesopraocis) arenicola sp. nov. Praocis (Mesopraocis) flava Kulzer, 1958 is synonymised with P. (M.) pilula Laporte, 1840. Other species of the subgenus are: P. (M.) calderana Kulzer and P. (M.) nitens Kulzer. A statement on the variation in the number of antennomeres in P. (M.) pilula is appended.
Atacama, Chile, conical pegs sensilla, fossorial adaptations, Mesopraocis, new species
Praocis Eschscholtz is the type genus of the Praociini, an endemic Neotropical tribe of Pimeliinae with 149 species/subspecies arranged in 15 genera (
Of the nine subgenera of Praocis, six of them inhabit northern and central Chile from 25° South to 42° South: Praocis s. str., Orthogonoderes Gay & Solier, Filotarsus Solier, Mesopraocis Flores & Pizarro-Araya, Postpraocis Flores & Pizarro-Araya, and Anthrasomus Guérin-Méneville (
As with most members of Pimeliinae, species of Praocis are flightless (
Praocis (Mesopraocis) Flores & Pizarro-Araya, 2014 comprises four species endemic to Northern Chile, inhabiting coastal areas from 25° South (Paposo, Antofagasta Region) to 31° South (Caleta Limarí, Coquimbo Region). The objectives of this study are to revise the subgenus Praocis (Mesopraocis) by incorporating new characters from external morphology and genital features, to describe a new species, to detail their geographic distribution, and to analyze the fossorial adaptations of the species to sandy habitats. In
The present study is based on examination of specimens borrowed from the following collections and curators (we follow
For this research we have searched for the type series of the species Praocis (Mesopraocis) pilula Laporte, 1840. According to
Measurements were recorded with a micrometer eyepiece microscope. Body length was measured dorsally, along the midline, from the anterior margin of the labrum to the apex of elytra. Terminology used in descriptions follows recent papers dealing with the genus Praocis (
Terminology of protibial sensilla follows
The phylogenetic species concept of
Scanned electron micrographs (Figs
Scanning electron micrographs of body details of Praocis (Mesopraocis) pilula A head in dorsal view, 45× B antenna with 11 antennomeres, dorsal view, 70× C antenna with 10 antennomeres, ventral view, 100× D antenna with 9 antennomeres, dorsal view, 160× E prosternum and hypomeron, 25× F meso, metaventrite, abdomen, and pseudopleuron, 17×.
Scanning electron micrographs of body details of Praocis (Mesopraocis) pilula A protibia, posterior face, 37× B protibia, anterior face, 65× C conical pegs sensilla type 1 (CP1) (on outer margin of tibia), 700× D conical pegs sensilla type 2 (CP2) (on antero-distal margin of protibia), 750×. Arrows indicate conical pegs sensilla type 1.
Exact label data are cited only for the holotypes, where brackets delimit the text of individual labels and new lines on the same label are separated by a diagonal slash (/). Geographic coordinates of the collecting sites were recorded using a GPS Garmin eTrex, Vista C. The distribution map was generated using ArcMap 9.0 (Environmental Systems Research Institute, Redlands, California). For distribution of the species we used the biogeographic classification of
Praocis (Mesopraocis) Flores & Pizarro-Araya, 2014: 60. Type species: Praocis calderana Kulzer, 1958 (original designation).
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.
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.
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.
Legs. Distance between meso- metacoxae exceeding half mesocoxal length (Fig.
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.
Male and female genitalia of Praocis (Mesopraocis) species A-D male A, B Praocis (Mesopraocis) calderana, dorsal and ventral views C, D Praocis (Mesopraocis) nitens, dorsal and ventral views. Abbreviations: bl, basal lamina of tegmen, ls, lateral styles of tegmen, ml, median lobe E ovipositor (ventral view), spiculum ventrale and internal female reproductive tract of Praocis (Mesopraocis) pilula. Abbreviations: bc, baculi of coxite, bp, baculi of paraproct, c, coxite, g, gonostyli, m, midventral sclerite, o, oviduct, p, paraproct, r, rectum, s, spermatheca, sag, spermathecal accessory gland, sp, spiculum ventrale, v, vagina, 1, 2, 3, 4, coxite lobes. Scale bars: 1 mm.
Female terminalia and genitalia (Fig.
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 (
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 (
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 (
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 (
1 | Pronotum with posterior angles not produced, central area of posterior margin extending beyond lateral extents of posterior margin; body widest behind elytral humeri; antennae reaching anterior quarter of lateral margin of pronotum; pseudopleuron with punctures equal density on all surface, separated by two to four puncture diameters from which emerge decumbent setae (Fig. |
Praocis (Mesopraocis) pilula Laporte |
– | Pronotum with posterior angles produced, central area of posterior margin not extending beyond lateral extents of posterior margin; body widest at prothorax; antennae reaching anterior third of lateral margin of pronotum; pseudopleuron with punctures separated by three to six puncture diameters on lower surface and separated by one to two puncture diameters on upper surface from which emerge erect setae | 2 |
2 | Upper margin of eyes lacking supraocular groove; antennomere 9 wider than long and equal length to 10; first metatarsomere twice as long as metatarsomeres 2–3 combined (Fig. |
Praocis (Mesopraocis) calderana Kulzer |
– | Eyes with supraocular groove, starting in the middle of upper margin of eye and ending on upper postgenal margin; antennomere 9 longer than wide or equal length than wide, and longer than 10; first metatarsomere 1.4–1.6 × longer than metatarsomeres 2–3 combined | 3 |
3 | Frons, epicanthus and elytra with impressed punctures, frons and epicanthus with puncture depth the same size than diameter, elytra with puncture depth larger than diameter; antennomere 9 longer than 11 and narrow than 10, antennomere 11 wider than long; posterior ¾ of epipleuron with a row of punctures the same diameter and depth than punctures on pseudopleuron (Fig. |
Praocis (Mesopraocis) nitens Kulzer |
– | Frons, epicanthus and elytra with shallow punctures, frons and epicanthus with puncture depth smaller than diameter, elytra with puncture depth the same size than diameter; antennomere 9 of equal length than 11 and of equal width to 10, antennomere 11 longer than wide; posterior ¾ of epipleuron with a row of punctures smaller diameter and depth than punctures on pseudopleuron (Fig. |
Praocis (Mesopraocis) arenicola sp. nov. |
Praocis pilula
Laporte, 1840: 187;
Coelus hirticollis
Solier, 1840: 212;
Praocis flava
Kulzer, 1958: 32 (rev.);
Length 5.00–9.25 mm. Body, antennae, legs black, dark brown to light brown, body widest behind elytral humeri. Head. Clypeus with punctures bearing short setae on centre and long setae at sides, width of anterior margin exceeding half the interocular width; frons with punctures bearing short setae on centre and long setae at sides and posterior half (Fig.
Thorax. Pronotum with anterior angles rounded, not produced, remote from eyes and epicanthus, lateral margins declivous, disc convex reaching lateral margins (Fig.
Elytron. Pseudopleuron with abundant punctures from which emerge long, golden, decumbent setae, punctures equally dense on all surface, separated by two to four puncture diameters (Fig.
Legs. Ventral surface of protrochanters with hair brush. Apical process of distal margin of protibiae equal to length of protarsomeres 1–3 combined; protibial length twice the width of distal margin. First metatarsomere 1.4–1.6 times longer than metatarsomeres 2–3 combined (Fig.
Abdomen. Ventrites 1–3 with sparse punctures separated by two to four puncture diameters; ventrite 4 with sparse punctures separated by one to two puncture diameters; ventrite 5 with punctures on central area separated by two to four puncture diameters, on lateral thirds separated by one to two puncture diameters.
Male genitalia. Basal lamina of tegmen equal width throughout, with base concave. Lateral styles of tegmen with proximal margin straight, slightly bisinuate at sides, with setae on distal 1/5 of ventral surface. Median lobe proximally narrow, half the width of tegmen, with apical aperture small.
Intraspecific variation. Antennae can exhibit 9, 10 or 11 antennomeres, the same individual can bear both antennae with different number of antennomeres (Fig.
Allotype of Praocis (Mesopraocis) flava: [Coquimbo] [Alotypus/ Praocis/ flava m./ det. H. Kulzer 1957] (
Chile. Atacama Region: Copiapo Province: E. Rodillo sand dunes 476 m, 27°1'5.3"S, 70°40'36."W, 30.x.2012, M. Elgueta, 9 (IADIZA), Rodillo sand dunes 14 m, 27°00'6.1"S, 70°47.4'10."W, 30.x.2012, M. Elgueta, 1 (IADIZA), Punta Frodden, 20 km N. Caldera, 26.iv.1956, L.E. Peña, 30 (
Praocis calderana
Kulzer, 1958: 32 (rev.);
Length 6.25–9.00 mm. Body, antennae, legs black, dark brown to light brown, body widest at prothorax. Head. Clypeus with punctures bearing short setae on all surface, width of anterior margin equal to half the interocular width; frons with punctures bearing short setae on all surface, border of punctures not elevated; frontoclypeal suture lacking setae; eyes lacking supraocular groove; antennae reaching anterior third of lateral margin of pronotum; antennomere 9 wider than long, 11 longer than wide, antennomere 9 of equal length to 10 and shorter than 11, antennomere 9 of equal width to 10 and wider than 11, antennomere 10 wider than 11.
Thorax. Pronotum with anterior angles rounded, produced, very close to eyes and epicanthus, lateral margin explanate, disc convex not reaching lateral margins (Fig.
Elytron. Pseudopleuron with sparse punctures of which emerge short, erect setae, becoming long, dense on anterior half of upper surface, punctures separated by three to six puncture diameters on lower surface, separated by one to two puncture diameters on anterior half of upper surface; epipleuron with a fringe of long golden setae on anterior half of edge, texture different than that of elytron, shiny, almost smooth, with sparse punctures and setae.
Legs. Ventral surface of trochanters with single long setae. Apical process of distal margin of protibiae equal to length of protarsomeres 1–3 combined; protibial length twice the width of distal margin. Metatarsomere 1 twice as long as metatarsomeres 2–3 combined.
Abdomen. Ventrites 1–3 with sparse punctures separated by two to four puncture diameters; ventrite 4 with sparse punctures separated by one to two puncture diameters; ventrite 5 with punctures on central area separated by two to four puncture diameters, on lateral thirds separated by one to two puncture diameters.
Male genitalia (Fig.
Holotype male: [Caldera/ (8 km SE)/ Costa Atacama/ 17.vi.1955/ Coll: L.E. Peña] [Holotypus/ Praocis/ calderana m./ det. H. Kulzer 1957] (
Chile. Antofagasta Region: Antofagasta Province: Antofagasta. 20 km N Paposo, vi.1985, L.E. Peña, 4 (
Praocis nitens
Kulzer, 1959: 561;
Length 7.87–10.62 mm. Body, antennae, legs black to dark brown, body widest at prothorax. Head. Clypeus with punctures bearing short setae on all surface, width of anterior margin equal to half the interocular width; frons with punctures bearing short setae on all surface, border of punctures on frons and epicanthus elevated; frontoclypeal suture with short or long setae; eyes with supraocular groove; antennae reaching anterior third of lateral margin of pronotum; antennomere 9 longer than wide, 11 wider than long, antennomere 9 longer than 10 and 11, antennomere 9 narrower than 10 and wider than 11, antennomere 10 wider than 11.
Thorax. Pronotum with anterior angles rounded, not produced, remote from eyes and epicanthus, lateral margins declivous, disc convex reaching lateral margins (Fig.
Elytron. Pseudopleuron with sparse punctures of which emerge long, erect setae, becoming long, dense on anterior half of upper surface, punctures separated by three to six puncture diameters on lower surface, separated by one to two puncture diameters on anterior half of upper surface; epipleuron with a fringe of long golden setae on anterior half of edge, shiny, almost smooth, with sparse punctures and setae on anterior quarter, and with a row of punctures with same diameter and depth as on pseudopleuron located on posterior three fourths.
Legs. Ventral surface of protrochanters with hair brush. Apical process of distal margin of protibiae equal to length of protarsomeres 1–2 combined; protibial length 2.5 times the width of distal margin. First metatarsomere 1.4–1.6 times longer than metatarsomeres 2–3 combined (Fig.
Abdomen. Ventrites 1–2 with sparse punctures separated by two to four puncture diameters; ventrites 3–4 smooth on central area, with punctures on lateral thirds separated by two to four puncture diameters; ventrite 5 with punctures on central area separated by two to four puncture diameters, on lateral thirds separated by one to two puncture diameters.
Male genitalia (Fig.
Holotype male: [Huasco/ Atacama/ 20–22.x.1957/ Coll: L.E. Peña] [Holotypus/ Praocis/ (Mesopraocis)/ nitens m./ det. H.
Chile. Atacama Region: Copiapo Province: Rodillo, Caldera, xi.1991, H. Vásquez, 10 (
The specific epithet is a Latin adjective, referring to the fact that this species inhabits sandy places.
Pronotum with central area of posterior margin not extending beyond lateral extents of posterior angles; body widest at prothorax; width of anterior margin of clypeus equal to half the interocular width. Praocis (Mesopraocis) arenicola sp. nov. superficially resembles Praocis (Mesopraocis) nitens by having pronotum with lateral margins declivous, disc convex reaching lateral margins; eyes with supraocular groove; antennomere 9 longer than wide or equal length than wide, and longer than 10. Praocis (Mesopraocis) arenicola sp. nov. differs from P. (M.) nitens by having frons, epicanthus, elytron with shallow punctures; frons and epicanthus with puncture depth smaller than diameter; elytron with puncture depth the same size than diameter; antennomere 9 of equal length than 11 and of equal width to 10; antennomere 11 longer than wide. Praocis (Mesopraocis) nitens has frons, epicanthus, elytron with impressed punctures; frons and epicanthus with puncture depth the same size than diameter; elytron with puncture depth larger than diameter; antennomere 9 longer than 11, narrower than 10; antennomere 11 wider than long.
Length 6.62–10.00 mm. Body, antennae, legs black to dark brown, body widest at prothorax. Head. Clypeus with punctures bearing short setae on all surface, width of anterior margin equal to half the interocular width; frons with punctures bearing short setae on all surface, border of punctures not elevated; frontoclypeal suture with short setae; eyes with supraocular groove; antennae reaching anterior third of lateral margin of pronotum; antennomeres 9 and 11 longer than wide, antennomere 9 longer than 10 and shorter than 11, antennomere 9 of equal width to 10 and wider than 11, antennomere 10 wider than 11.
Thorax. Pronotum with anterior angles rounded, not produced, remote from eyes and epicanthus, lateral margins explanate, disc convex not reaching lateral margins (Fig.
Elytron. Pseudopleuron with sparse punctures from which emerge long, erect setae, becoming a dense fringe on anterior half of upper surface, punctures separated by three to six puncture diameters on lower surface, separated by one to two puncture diameters on anterior half of upper surface; epipleuron with a fringe of long golden setae on anterior half of edge, almost smooth, with sparse punctures and setae on anterior quarter and with a row of punctures smaller diameter and depth than on pseudopleuron located on posterior three fourths.
Legs. Ventral surface of protrochanters with hair brush. Apical process of distal margin of protibiae equal to length of protarsomeres 1–3 combined; protibial length 2.5 times the width of distal margin. First metatarsomere 1.4–1.6 times longer than metatarsomeres 2–3 combined.
Abdomen. Ventrites 1–3 with sparse punctures separated by two to four puncture diameters; ventrite 4 with sparse punctures separated by one to two puncture diameters; ventrite 5 with punctures on central area separated by two to four puncture diameters, on lateral thirds separated by one to two puncture diameters.
Male genitalia. Basal lamina of tegmen equal width throughout, with base concave. Lateral styles of tegmen with proximal margin concave, with setae on distal 1/6 of ventral surface. Median lobe equal width throughout, one third the width of tegmen, with apical aperture small.
Holotype male: [Chile: III Región, Chañaral/ sur Flamenco dunas/ 58m 26°35'55.9"S, 70°35'45"W, 30.x.2012/ Coll: Mario Elgueta] [Praocis (Mesopraocis)/ arenicola sp. nov./ HOLOTYPUS male/ Det. G. Flores and/ J. Pizarro-Araya 2021] (
Chile. Atacama Region: Copiapo Province: Torres del Inca, 26.60759°S, 70.69839°W, x.2017, Coll: A. Zúñiga, 2 (IADIZA).
Members of Praocis (Mesopraocis) inhabit loose sands of coastal grassy dunes covered with more or less scattered vegetation and according to the
All species of Praocis (Mesopraocis) spend most of their lives within the substrate (larvae, pupae, and adults) and they possess many of the morphological modifications described by
Body subglobular. This shape of the body increases the volume of the subelytral cavity which is hypothesised to be a protection from heat and to reduce respiratory water loss (
Very short antennae. In taxa that burrow through loose sand, the antennae often become shortened, sometimes with the fusion of segments (
Foretibia shape. In sand-burrowing or sand-swimming forms, the foretibiae are commonly specialized as lamellate digging tools as in Eusattus muricatus and ciliatus species groups (
Pronotal setal fringe. Burrowing Pimeliinae often have fimbriate lateral body margins. Usually the setae are set on the lateral margin of pronotum (= carina of
All species of Praocis (Mesopraocis) have elytral surface texture smooth, lacking rugosity and tubercles, devoid of carinae or striae, and lateral margin not defined (Fig.
It has been hypothesised that psammophily has evolved independently in a number of unrelated taxa (
We acknowledge curators for the loan of type specimens. We thank CONAF (the Chilean National Forestry Corporation) for permitting us to work in protected areas (Projects N°018/2011, N°006/2014, N°028/2015, N°005/2017 and CONAF-SIMEF N°008/2017). We are grateful to Fermín M. Alfaro, Juan E. Barriga-Tuñon, Andres A. Ojanguren-Affilastro, Alberto Castex, Pablo Agusto, Juan E. Calderon, Álvaro Zúñiga-Reynoso, Reinhard Predel, Lapo Ragionieri, and Marcel Bläser for their assistance in the field. Luis Letelier (University of Talca) for providing Geographic Information System (GIS) support. To Silvina Lassa for help with preparing SEM photos (MEBYM – Laboratorio de Microscopía Electrónica de Barrido y Microanálisis, IANIGLA – CONICET, Mendoza). To Rolf Aalbu, Alfredo Giraldo-Mendoza and Kojun Kanda (reviewers) for suggestions improving the manuscript. Research by GEF was partially supported by CONICET, Argentina, NSF DEB-1754630 (USA), and by the Deutsche Forsch – ungsgemeinschaft (DFG, German Research Foundation) – Projektnummer 268236062 – SFB 1211. Trip to Budapest Museum of GEF was supported by CONICET, Argentina and by a grant awarded by The Ernst Mayr Grants Committee (Harvard University). JPA thanks DIDULS PR2121210 and DIDULS PEQMEN212124 projects of the University of La Serena, La Serena, Chile, to the funding of the Ministry of Education of Chile, through the MINEDUC performance agreement: Implementation of a competitive model of innovation and creation: preparing the University of La Serena for 2030, ULS19101 and the Integrated Forest Ecosystem Assessment and Monitoring System (SIMEF by its Spanish acronym), INFOR-IEB Agreement.