Ischyrus Lacordaire 1842
Creators: name: Skelley, Paul E.
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Erotylidae
Ischyrus

description: Genus ISCHYRUS Lacordaire 1842   
 Ischyrus Lacordaire 1842: 89-131. Type species: Erotylus quadripunctatus Olivier 1792: 431,437; subsequent designation by Crotch 1873a: 353; 1873b: 144. Name conservation proposal by Skelley and Goodrich 1994; conservation ruling and acceptance in ICZN 1996. ~ Skelley 1998b: 1-134 [partial revision].   
 Micrischyrus Alvarenga 1965: 86. Type species: Erotylus quadripunctatus Olivier 1792: 431,437; original designation. New name for Ischyrus Lacordaire 1842, sensu Crotch 1873a,b, not Ischyrus Dejean 1836: 428. ~ Alvarenga 1994: 12-17.   
 Diagnosis. Ischyrus has historically been characterized by coarsely faceted eyes, triangular mental plate, relatively compact antennal club with antennomere IX transverse and semicircular, terminal antennomeres always black, terminal maxillary palpomere being wider than the terminal labial palpomere, femora with distinct marginal bead; and body unicolorous black to distinctly patterned.   
 Description. [Modified from Skelley (1998b) to be directly comparable with other tritomine genera treated here. Refer to Skelley (1998b) for additional descriptive details.] Length 3.5-9.9 mm; width 1.9-5.5 mm. Body shape parallel-sided, to elongate, slightly flattened to convex dorsally; weakly microreticulate, surface dull to shining; dorsal punctation coarse; unicolorous black to variously banded or spotted, yelloworange with black pattern, never blue; terminal antennomeres and legs always brown to black, never pale.   
Head usually coarsely punctate; ocular striae present, not surpassing antennal base anteriorly; stridulatory files present in some. Eyes prominent, coarsely faceted. Antennae elongate, rarely attaining the base of the pronotum, usually only attaining basal quarter; antennomere II globose, length usually slightly greater than width; antennomere III length = 3 x width; antennomeres IV-VIII variously proportioned but always longer than wide; antennomere VIII little wider than VII, apically angled, not appearing as part of club; antennomere IX broad, semicircular to trapezoidal at base, width = 1.0-1.5 x length. Mentum with triangular plate, width = length. Terminal maxillary palpomere symmetrical or asymmetrical, triangular to somewhat hemispherical, width = 1.5-2.0 x length. Terminal labial palpomere expanded medially, asymmetrical, length = 0.5-1.5 x width, width = 0.25-0.80 x width of terminal maxillary palpomere. Genal lobes weakly developed, sharply edged, rounded.  
Pronotum with anterior marginal bead only behind eyes; base lacking marginal bead; sides at anterior angle arch toward eyes; base with small group of coarse puncture in shallow depression on either side of midline. Wings present, fully developed.  
Prosternum with anterior marginal bead, usually pinched medially. Mesosterum posteriorly slightly sinuate, transverse, width = 1.5 x length, punctation small to moderate, usually indistinct. Mesocoxal lines on metasternum absent to moderate in length, often distinct. Metasternum not shortened, distance between meso-and metacoxae = approximately 2 x intermesocoxal width, sternal line faint medially. Meso- and metafemora angled in cross-section, with sharp posterior marginal bead. Male genitalia with flagellum thin and hair-like, rarely thickened or modified.  
 Distribution. Ischyrus is restricted to the New World (Canada to Argentina), with highest diversity in mainland tropical areas.   
 Larvae. This diagnosis is based I. quadripunctatus from the US (illustrated in Skelley 1998b). Head bicolored, mostly pale with broad dark patches separated by pale bands along frontal suture and gena; T1 notum pigmented, with pale lateral arch creating a fake eye-spot; T2-A9 dorsally pigmented. T1-A8 terga with distinct prominent marginal tubercles and tergal surfaces with prominent tubercles which become larger and more spine-like on posterior segments, tubercles of more posterior segments often bifid; A9 tergum with urogomphi prominent, short, well separated; spiracles of A1-8 weakly raised. Larvae of I. quadripunctatus have been collected on resupinate white polypore fungi growing on suspended dead wood (P. Skelley, pers. obs.). Skelley et al. (1991) and Goodrich and Skelley (1993) provide specific host records for this and other Erotylinae. More detailed descriptions for immature I. quadripunctatus can be found in Chapuis and Candèze (1853), Chapuis (1876), Weiss (1920), and Skelley (1988, including pupa; 1998b).   
 Remarks. As presently understood, Ischyrus has over 60 species, mostly tropical, but many more await description. The North and Central American members were recently revised (Skelley 1998b), but much work remains before there is a clearer understanding of generic limits for South American members and their relationship with Megischyrus Crotch (1873b). Ischyrus (sensu lato) is an assemblage of several distinct lineages, and the creation of Cubyrus is the first action to recognize and define one of these lineages. Only one member of Ischyrus is present in the West Indies, the widespread I. quadripunctatus (Olivier).
description: Published as part of Skelley, Paul E., 2009, Pleasing fungus beetles of the West Indies (Coleoptera: Erotylidae: Erotylinae), pp. 1-94 in Insecta Mundi 2009 (82) on pages 48-49, DOI: 10.5281/zenodo.5405085