Ligyrus Burmeister, 1847

López-García, Margarita M. & Deloya, Cuauhtémoc, 2022, Cladistic analysis reveals polyphyly of Tomarus (Coleoptera: Scarabaeidae: Dynastinae): new classification and taxonomic revision, Zootaxa 5211 (1), pp. 1-119 : 22-24

Genus Ligyrus Burmeister, 1847 revised status

Ligyrus Burmeister, 1847: 542 .

Type species: Scarabaeus gibbosus DeGeer, 1774 by subsequent designation ( Casey 1915: 178).

Ligyrodes Casey, 1915: 179 .

Type species: Scarabaeus relictus Say, 1825: 194 by original designation.

Ligyrellus Casey, 1915: 206 (as subgenus).

Type species: Podalgus villosus Burmeister, 1847: 120 here designated.

Oxygrylius Casey, 1915: 208 new synonym.

Type species: Ligyrus ruginasus LeConte, 1856: 20 by original designation.

Description. (n = 5,691). Length 11.3–21.8 mm. Humeral width 5.9–11.5 mm. Head: Clypeus triangular, subtriangular, or trapezoidal ( Fig. 1C–G ). Apex of clypeus with 1 or 2 triangular to transverse teeth, not or slightly separated. Ocular canthus rounded to acute, with or without ventral setae, without dorsal setae. Frons with tumescences or high carina, entire or interrupted at middle. Mentum triangular to subrectangular ( Fig. 2A–E ); surface flat to strongly convex. Mentum and ligula separate or fused dorsally. Ligula reduced or well developed, covered with short, sparse or long, dense setae; ligular lobes fused or not. Maxillary apical palpomere 2.0–2.5 times longer than the second. Maxilla with galea rectangular (3.0–3.5 times longer than wide); with 3–6 well-developed teeth, sometimes with 1 to 2 rudimentary teeth. Mandible with 2 apical teeth and a lateral widely rounded lobe; tooth 1 with apex acute, longer and narrower than tooth 2. Labrum subquadrate (as long as wide) to rectangular; apex rounded to slightly bilobed; with long, dense setae. Antenna with 10 antennomeres, club long to very long (1.5–2.0 times longer than antennomeres 2–7). Pronotum: Apical marginal bead complete. Apex with or without tubercle; without fovea or with deep, wide fovea. Elytra: Inner surface of apex with transverse, small tubercles forming 50–166 parallel lines. Wings: RA with dense, large peg-like setae on medial ventral region; with peg-like setae on dorsal surface ( Fig. 7B–E ). Edge of RA 3 with dense to sparse setae. Abdomen: Apex of tergite IV with a diagonal line of 9–14 short to large, transverse, parallel carinae. Sternite VIII emarginate in male; entire in female. Pygidium without rugosity. Propygidium without stridulatory area. Venter: Prosternum narrow, acute to slightly rounded. Propleura with long, dense setae on all the surface, sparser on medial area. Apex of prosternal process spherical to flat; with or without dorsal long setae. Metepisternum with incomplete, very thin carina; inner surface with deep, large punctures, with long setae; outer surface homogeneously rugose, with long, dense setae. Metasternum with small, deep, confluent punctures; with long, dense setae. Legs: Male protarsus simple or enlarged; inner claw simple or enlarged ( Fig. 10C–E ). Protibia tridentate, sometimes with denticles ( Fig. 11E ); basal tooth slightly distant from others. Metafemur with well-defined anterior row of punctures. Apical margin of mesotibia and metatibia entire to crenulate. Female genitalia: Subcoxite 1.5–2.0 times wider than long. Coxite subquadrate (as long as wide) to subrectangular (wider than long); surface flat to strongly concave. Subcoxite wider and subequal to longer than coxite. Male genitalia: Phallobase 1.2–1.3 times longer than parameres. Parameres without dorsal teeth (rarely with a dorsal long teeth), with ventral tooth. Internal sac with copulatory lamella and short to long lamellar spiny belt; accessory lamella simple (entire structure with shapes variable among the species).

Diagnosis. Ligyrus can be differentiated from other Pentodontini by the following: frontoclypeus with carina or tumescences; antennal club long to very long (1.5–2.0 times as long as antennomeres 2–7); mentum triangular to subrectangular ( Fig. 2A–E ); ligula narrow to wide; ligular lobes fused or not, with a narrow emargination; galea with 3–6 teeth ( Fig. 3A–C ); pronotum with apical marginal bead complete; pronotal tubercle small to large; fovea deep, oval to triangular or absent; metepisternum with long setae; protibia tridentate, with or without additional denticles, basal tooth distant from others ( Fig. 11C–G ); protarsus of male simple or enlarged ( Fig. 10C ); internal sac with copulatory lamella and lamellar spiny belt, accessory lamellae simple ( Fig. 21C–E ); surface of coxite flat to strongly concave ( Fig. 13C–G ); and stridulatory apparatus consisting of a diagonal strip of short, transverse, parallel carinae on apex of sternite IV ( Fig. 8B–C ) and apical inner surface of elytra with transverse small tubercles forming parallel lines ( Fig. 8E–F ).

Composition. Eighteen species. Tomarus adoceteus , T. pullus , and P. cicatricosus considered by Morón & Grossi (2015) in the genus Ligyrus are excluded and placed in other genera, while L. ruginasus and L. peninsularis (previously in Oxygrylius ) are included in Ligyrus , as well as three species described recently in the genus Tomarus : L. spinipenis , L. moroni , and L. paranaensis . It is difficult to assess whether the fossil species Ligyrus compositus Wickham, 1911 and L. effetus Wickham, 1914 from Florissant, Colorado (Late Eocene) belong to Ligyrus , but any diagnostic character of the genus coincides with the descriptions or illustration of the fossils presented by Wickham (1911, 1914).

Geographic distribution. Species of Ligyrus are found from southeastern Canada to northern Argentina, including the West Indies, in deserts and dry to humid forests (mainly pine/oak and cloud forests). No species are found in Amazonia.

Phylogenetic relationships. Ligyrus (sensu Morón & Grossi 2015) was found as a heterogeneous group of three subgenera Ligyrus (sensu stricto), Anagrylius , and Ligyrodes , which coincided in part with the Casey (1915) subgenera. Ligyrus (sensu stricto) is paraphyletic with respect to Oxygrylius as its species are closely related, especially those from North America.

Taxonomic remarks. Burmeister (1847) described the genus Ligyrus to group some species of Heteronychus and Podalgus with a kind of stridulatory apparatus on the inner surface of the elytra, which is not found in other Dynastinae . Casey (1915) separated the group in three genera ( Ligyrus , Ligyrodes , and Oxygrylius ) and several subgenera as shown in Table 1. Then, Endrödi (1969) presented a different classification using part of the Casey subgenera for Ligyrus and considering Oxygrylius as a different genus. The name Ligyrus was maintained as a valid name for more than 150 years until Ratcliffe (2003) revalidated the name Tomarus by having priority over Ligyrus , and his proposal was widely accepted. Morón & Grossi (2015) separated the genus into Ligyrus and Tomarus , grouping the species by the number of mandibular teeth, and presence of a pronotal fovea. Ligyrus (sensu Morón & Grossi 2015) coincides only in part with the classification presented in this work. Oxygrylius has been treated as a separate genus for most authors except Hardy (1964), who considered it a synonym of Bothynus (name used erroneously for species of Ligyrus ). Hardy (1964) found a specimen of L. gibbosus with triangular apex as in Oxygrylius , and so he thought it could be caused by a mutation in a single character. That is consistent with the results of the cladistic analysis, as there are many other characters supporting the grouping of these two species with Ligyrus , particularly with Ligyrus (sensu stricto) (i.e., presence of frontoclypeal carina, mentum triangular, galea rectangular, coxite strongly concave, structure of the stridulatory apparatus, shape of accessory lamella, etc.).

Key to the subgenera of Ligyrus

1 Head with carina, complete or interrupted at middle ( Fig. 1E–G ). Antennal club very long (2 times longer than antennomeres 2–7). Ocular canthus with ventral setae. Mentum triangular, very narrow at apex ( Fig. 2B–D ). Mesotibia strongly narrowed before apex ( Fig. 12E–F ) and long (as long as mesotarsus).Apical margin of mesotibia and metatibia entire to slightly crenulate ( Fig. 12E–F, K–L ). Metacoxa with setae on anterior corners. Accessory lamella irregular, elongate ( Fig. 21C–E ).... Ligyrus

- Head with tumescences ( Fig. 1C–D ). Antennal club long (1.5–1.7 times longer than antennomeres 2–7). Ocular canthus without ventral setae. Mentum subrectangular (base as wide as apex) ( Fig. 2A, E ). Mesotibia slightly narrowed before apex and short (shorter than mesotarsus). Apical margin of mesotibia and metatibia crenulate ( Fig. 12C–D, I–J ). Metacoxa without setae on anterior corners. Accessory lamella T or U-shaped........................................................... 2

2 Pronotum with small tubercle and fovea. Prosternal process spherical with dorsal setae, without transverse sulcus. Protibia without basal denticle ( Fig. 11C ). Male protarsus with inner claw simple. Internal sac with raspula; accessory lamella T-shaped ( Fig. 21C ). Female coxite strongly concave ( Fig. 13C )............................................... Anagrylius

- Pronotum without tubercle or fovea. Prosternal process flat without dorsal setae, with deep transverse sulcus. Protibia with basal denticle ( Fig. 11D–E ). Male protarsus enlarged, with inner claw subrectangular, apex truncate and a small acute projection ( Fig. 10C–E ). Internal sac without raspula; accessory lamella U-shaped ( Fig. 21D ). Female coxite flat ( Fig. 13D ). Ligyrodes

Figures

FIGURE 1. Head. A) Euligyrus ebenus, B) Proculigyrus cicatricosus, C) Ligyrus (Ligyrodes) peruvianus, D) L. (Anagrylius) moroni, E) L. (Ligyrus) ruginasus, F) L. (Ligyrus) nasutus, G) L. (Ligyrus) bidentulus, H) Tomarus adoceteus, I) T. maimon, J) T. pullus, K) T. pumilus.

FIGURE 2. Labium. A) Ligyrus (Anagrylius) moroni, B) Ligyrus (Ligyrus) allonasutus, C) L. (Ligyrus) gibbosus, D) L. (Ligyrus) villosus, E) L. (Ligyrodes) relictus, F) Proculigyrus cicatricosus, G) Euligyrus ebenus, H) E. similis, I) Tomarus gyas, J) Tomarus selanderi, K) Tomarus subtropicus. Abbreviations: LL: Ligular lobes, LP: Labial palpus, M: Mentum, S: Suture.

FIGURE 3. Maxilla. A) Ligyrus (Anagrylius) moroni, B) L. (Ligyrodes) sallaei, C) Ligyrus (Ligyrus) allonasutus. Numeration of teeth of galea: D) Euligyrus similis, E) L. (Ligyrodes) sallaei, F) Tomarus gyas, G) L. (Ligyrus) fossor, H) L. (Ligyrus) allonasutus.

FIGURE 7. Left hindwing in ventral view. A, C) Euligyrus similis, B, D) Ligyrus (Anagrylius) cuniculus, E) L. (Ligyrus) burmeisteri, F) Tomarus gyas, G) T. maternus, H) T. rostratus.

FIGURE 8. Stridulatory apparatus. A, D) Proculigyrus cicatricosus, B, E) Ligyrus (Ligyrus) burmeisteri, C, F) L. (Ligyrodes) relictus, G, K) Tomarus amazonicus, H, L) T. maimon, I, M) T. maternus, J, N) T. gyas.

FIGURE 10. Protarsus and inner claw. A–B) Euligyrus similis, C–E) Ligyrus (Ligyrodes) sallaei.

FIGURE 11. Protibia in frontal view.A) Euligyrus similis, B) Proculigyrus cicatricosus, C) Ligyrus (Anagrylius) moroni, D) L. (Ligyrodes) relictus, E) L. (Ligyrodes) sallaei, F) L. (Ligyrus) allonasutus, G) L. (Ligyrus) villosus, H) Tomarus bituberculatus, I) T. colombianus, J) T. pullus.

FIGURE 12. Mesotibia (A–F). A) Euligyrus similis, B) Proculigyrus cicatricosus, C) Ligyrus (Anagrylius) moroni, D) L. (Ligyrodes) sallaei; E) L. (Ligyrus) allonasutus, F) L. (Ligyrus) villosus. Metatibia (G–L). G) Euligyrus similis, H) Proculigyrus cicatricosus, I) Ligyrus (Anagrylius) moroni, J) L. (Ligyrodes) sallaei, K) L. (Ligyrus) allonasutus, L) L. (Ligyrus) villosus.

FIGURE 13. Female genital plates. A) Euligyrus ebenus, B) Proculigyrus cicatricosus, C) Ligyrus (Anagrylius) moroni, D) L. (Ligyrodes) sallaei, E) L. (Ligyrus) allonasutus, F) L. (Ligyrus) bidentulus, G) L. (Ligyrus) neglectus, H) Tomarus laticaudus, I) T. maternus, J) T. rostratus, K) T. subtropicus. Abbreviations: SCx: Subcoxite, Cx: Coxite.

FIGURE 21. Internal sac. A) Euligyrus ebenus, B) Proculigyrus cicatricosus, C) Ligyrus (Anagrylius) moroni, D) L. (Ligyrodes) sallaei, E) L. (Ligyrus) allonasutus. Abbreviations:AL:Accessory lamellae, Br: Brush of setae, CL: Copulatory lamella, LSB: Lamellar spiny belt, Ra: Raspula.