Ligyrus Casey 1915
Creators: name: López-García, Margarita M.
name: Deloya, Cuauhtémoc
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Dynastidae
Ligyrus

description: Subgenus Ligyrus Casey, 1915 revised status
Ligyrus Casey, 1915: 192 (as subgenus).
Type species: Scarabaeus gibbosus De Geer, 1774 by subsequent designation (Casey 1915: 178).
Description. (n = 4,381). Length 11.3–18.0 mm. Humeral width 5.9–10.0 mm. Head: Clypeus triangular to subtriangular (Fig. 1E–G). Apex of clypeus with 1 or 2 triangular teeth, not or slightly separated. Ocular canthus rounded to acute, with ventral setae, without dorsal setae. Frons with carina, entire or interrupted at middle. Mentum triangular (Fig. 2B–D), surface flat to strongly convex. Mentum and ligula separate. Ligula reduced, covered with short, sparse setae; ligular lobes fused, apex straight. Maxillary apical palpomere 2.0–2.5 times longer than the second. Maxilla with galea rectangular (3.0–3.5 times longer than wide) (Figs. 3C, 4D–E); with 3–4 well-developed teeth (Fig. 3H), sometimes with 1–2 rudimentary teeth (Fig. 3G). Mandible with 2 apical teeth and a lateral widely rounded lobe (Fig. 5D–E); tooth 1 with apex acute, longer and narrower than tooth 2. Labrum subquadrate (as long as wide); apex rounded to slightly bilobed; with long, dense setae (Fig. 6A–B). Antenna with 10 antennomeres, club very long (2 times longer than antennomeres 2–7). Pronotum: Anterior marginal bead complete. Apex without tubercle or with acute tubercle; without fovea or with deep, wide fovea. Elytra: Inner surface of apex with transverse small tubercles forming 50–115 parallel lines (Fig. 8E–F). Wings: RA with dense, large peg-like setae on medial ventral region (Fig. 7E); with peg-like setae on dorsal surface. Edge of RA 3 with dense to sparse setae. Abdomen: Apex of tergite IV with a diagonal line of 9–11 short to large, transverse, parallel carinae (Fig. 8B–C). Sternite VIII emarginate in male; entire in female. Pygidium without rugosity (Fig. 9C–E). 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 slightly oval, with 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; inner claw simple. Protibia tridentate; basal tooth slightly distant from others (Fig. 11F–G). Apical margin of mesotibia and metatibia entire (Fig. 12E–F). Female genitalia: Subcoxite 1.5–2.0 times wider than long (Fig. 13E–G). Coxite subquadrate to subrectangular; surface flat to strongly concave. Subcoxite 2 times wider and longer than or subequal in length to coxite. Male genitalia: Phallobase 1.2–1.3 times longer than parameres. Parameres without dorsal teeth (rarely with a dorsal long tooth), with ventral tooth. Internal sac with copulatory lamella and short to long lamellar spiny belt; accessory lamella irregular (Fig. 21E).
Diagnosis. The subgenus Ligyrus can be differentiated by the following: Triangular to subtriangular clypeus (Fig. 1E–G), clypeal teeth triangular to transverse; frontoclypeus with carina entire or interrupted at middle (Fig. 1E–G); mentum triangular (Fig. 2B–D); mentum and ligula separate; ligula reduced; covered with short, sparse setae; ligular lobes fused; galea with 3–4 well-developed teeth, sometimes with 1–2 rudimentary teeth (Fig. 3C, G, H); antennal club very long; pronotum with or without fovea or tubercle; protibia tridentate, basal tooth slightly distant from others (Fig. 11F–G); protarsus of male simple, inner claw simple; internal sac with copulatory lamella and short to long lamellar spiny belt; accessory lamella irregular (Fig. 21E); stridulatory apparatus consisting of a diagonal line of 9–11 short to large, transverse, parallel carinae on apex of sternite IV and apical inner surface of elytra with transverse small tubercles forming 50–115 parallel lines.
Composition. Thirteen species are recognized as members of the subgenus Ligyrus.
Geographic distribution. This is the most widely distributed subgenus with species ranging from Argentina to Canada, including the West Indies. Species are mainly found in dry ecosystems such as deserts and dry forests.
Key to the species of the subgenus Ligyrus
1. Frontoclypeal carina interrupted at middle (Fig. 1G). Mesotibia not or only slightly narrowed before apex. Maxilla with 4–6 teeth. Species from the West Indies and South America....................................................... 2
- Frontoclypeal carina complete (Fig. 1E–F). Mesotibia strongly narrowed before apex (Fig. 12E). Maxilla with 3 teeth (Fig. 3C, H). Species from North or Central America................................................................. 8
2. Maxilla with 6 teeth (Fig. 3G). Parameres with a large, dorsal tooth on each side, apex straight (Fig. 15L). Female coxite strongly concave (Fig. 13G)............................................ Ligyrus (Ligyrus) fossor (Latreille, 1813)
- Maxilla with 4–5 teeth. Parameres without dorsal teeth with a ventral tooth each side, apex variable. Female coxite flat (Fig. 13F)................................................................................................ 3
3. Pronotum without fovea or tubercle....................................................................... 4
- Pronotum with fovea and tubercle. If fovea absent, then pronotum nearly smooth, with minute, sparse punctures.......... 6
4. Parameres with acute, triangular apex (Figs. 15P, 18H). Metatibia strongly narrowed before apex. Apex of metatibia with 19 spinules. Brazil .................................... Ligyrus (Ligyrus) paranaensis (López-García & Deloya, 2019)
- Parameres with apex truncate to round (Fig. 15K). Metatibia not narrowed before apex, sides nearly parallel. Apex of metatibia with 25–29 spinules................................................................................... 5
5. Parameres wide, with parallel sides, and minute spines on apicolateral 3rd; ventral teeth short, triangular. Argentina .. Ligyrus (Ligyrus) spinipenis (Neita & Ratcliffe, 2017)
- Parameres slender, apex narrowed, without spines on apicolateral 3rd; ventral teeth long (Fig. 15K). Bolivia, Argentina, and Brazil .......................................................... Ligyrus (Ligyrus) burmeisteri Steinheil, 1874
6. Frontal carina widely interrupted at middle. Pronotum and elytra nearly smooth, with minute, sparse punctures. Pronotal fovea absent. Pronotal tubercle absent, with a slight swelling at apex. Peru, Chile, and Argentina ........................................................................................... Ligyrus (Ligyrus) villosus (Burmeister, 1847)
- Frontal carina narrowly interrupted at middle. Pronotum and elytra strongly punctate, with small to large punctures. Pronotal fovea small to large. Pronotal tubercle large, conical to triangular............................................... 7
7. Pronotal fovea large, deep, about 1.2 times interocular width. Clypeus short and with lateral margins perpendicularly elevated. Clypeal teeth triangular to transverse, separated by a tooth diameter. Brazil, Argentina, and Uruguay ................................................................................... Ligyrus (Ligyrus) rubripes (Boheman, 1858)
-. Pronotal fovea small, shallow, 1/4 times interocular width. Clypeus long, strongly narrowed towards apex, lateral margins not elevated. Clypeal teeth long, acute, not separated. Argentina .............. Ligyrus (Ligyrus) bidentulus Fairmaire, 1892
8. Pronotum without fovea or tubercle (apex sometimes with small swelling)........................................ 9
- Pronotum with prominent fovea and tubercle.............................................................. 10
9. Frontoclypeal carina bilobed (Fig. 1F). Apex of pronotum with a small swelling. Ventral teeth of parameres long (Fig. 15N). Yucatán (Mexico)................................................ Ligyrus (Ligyrus) nasutus (Burmeister, 1847)
- Frontoclypeal carina straight. Apex of pronotum flat. Ventral teeth of parameres short (Fig. 15I). Western Mexico to Panama ............................................. Ligyrus (Ligyrus) allonasutus López-García & Deloya, new species
10. Clypeus triangular, ending in a central acute teeth, sometimes slightly bifid...................................... 11
- Clypeus subtriangular, with 2 acute to transverse teeth....................................................... 12
11. Parameres strongly widened at apex, without acute ventral teeth (Fig. 15S). Southeastern United States of America and northern Mexico .......................................................... Ligyrus (Ligyrus) ruginasus LeConte, 1856
- Parameres slightly widened at apex, with medial acute teeth (Fig. 15Q). Southwestern United States of America and Baja California Peninsula.................................................. Ligyrus (Ligyrus) peninsularis (Casey, 1915)
12. External surface of protibial, in frontal view, nearly smooth, with only minute, sparse punctures. Pronotum and elytra deeply punctate, punctures large, round. Apical half of parameres wide and with parallel sides, ventral tooth wide and located apically (Fig. 15O). United States of America .................................. Ligyrus (Ligyrus) neglectus (LeConte, 1847)
- External surface of protibia, in frontal view, deeply punctate. Pronotum and elytra with minute to small punctures. Apical half of parameres slender and slightly narrowed, ventral tooth triangular and located medially (Fig. 15M). United States of America and Mexico ....................................................... Ligyrus (Ligyrus) gibbosus (De Geer, 1774)
description: Published as part of López-García, Margarita M. & Deloya, Cuauhtémoc, 2022, Cladistic analysis reveals polyphyly of Tomarus (Coleoptera: Scarabaeidae: Dynastinae): new classification and taxonomic revision, pp. 1-119 in Zootaxa 5211 (1) on pages 35-36, DOI: 10.11646/zootaxa.5211.1.1, http://zenodo.org/record/7345007