Aegithus, Fabricius 1801

Skelley, Paul E., 2009, Pleasing fungus beetles of the West Indies (Coleoptera: Erotylidae: Erotylinae), Insecta Mundi 2009 (82), pp. 1-94 : 20-22

Genus AEGITHUS Fabricius 1801

Aegithus Fabricius 1801: 9 . Type species: Chrysomela clavicornis Linnaeus 1758 , by original designation according to Blackwelder 1947: 53, also by subsequent designation of Hope 1841: 114; after synonymy of Coccinella surinamensis Linnaeus under Chrysomela clavicornis Linnaeus. ~ Hope 1841: 114; Lacordaire 1842: 32, 276-295; Crotch 1873b: 145-147; Crotch 1876: 489-496; Chapuis 1876: 49, 55-56; Gorham 1888: 85-92; Kuhnt 1909: 9, 17; Kuhnt 1911: 8-11; Deelder 1942: 51, 57-59; Blackwelder 1945: 456-457; Alvarenga 1965: 81; Alvarenga 1994: 51-57; Dode 2000: 275.

Aegithomimus Mader 1942: 177. Type species: Aegithus (Aegithomimus) multistriatus Mader 1942 , by monotypy. ~ Alvarenga 1965: 81 [subgenus of Aegithus ]; Alvarenga 1977: 105 (synonymy).

Diagnosis. Defining characters for Aegithus are: clypeal sides not narrowed at base (wedge-shaped), and a globose, hemispherical body form ( Fig. 4, 6-7 , 38-39 ). Secondary diagnostic characters that are moderately variable among species include: coxal lines on metasternal surface ( Fig. 40-41 , lacking on many mainland species); meso- and metafemur with posterior marginal bead; antennomere IX length = antennomere XI ( Fig. 38-39 ); males with minute tomentose patch on first abdominal ventrite ( Fig. 40 ); coarse punctures at base of pronotum along nearly entire margin.

Description. Length 6.1-16.8 mm; width 4.6-14.5 mm. Body oval, rounded on sides and weakly to strongly hemispherical dorsally; body black to reddish-brown, some with elytral color patterns.

Head surface glossy to dull by microreticulation, punctures fine; clypeus width = 1.7-2.0 x length, divergent toward base or not, anterior edge truncate, surface punctures moderate in size; ocular striae attaining base of antenna or base of epistome. Antenna entirely black, antennomeres generally elongate; antennomere II subglobose; antennomere III length = 3 x width, as long as antennomeres IV+V combined; antennomeres IV-VII rounded apically, all equal in width; antennomere VIII somewhat triangular, angular apically, could be considered part of club; antennomere IX length = antennomere III, triangular or trapezoidal, sides divergent basally; antennomere X transverse; antennomere XI subcircular. Terminal maxillary palpomere triangular, weakly to strongly widened. Terminal labial palpomere triangularly dilated medially, not as wide as terminal maxillary palpomere. Mentum with raised triangular plate with distinct marginal bead, anterior angle acute to 90 o.

Pronotum glossy or dulled, punctation as on head, surface variably convex; strongly narrowed anteriorly, anterior edge medially straight, curving forward laterally, with fine entire marginal bead; anterior angles acute or broadly rounded, posterior angles approximately 90 o, angular or rounded; base sinuate or shallowly V-shaped, with weak medial lobe; base with marginal bead laterally or entirely lacking, often with row of coarse punctures along margin. Scutellum weakly triangular to weakly pentagonal, edges rounded, length = 1.0-1.2 x width. Elytra glossy or dull; lacking basal marginal bead; strial punctures visible or not, in rows or not, gemellate (paired) or not. Wings present, fully developed or not.

Prosternum variably convex, not keeled, but usually with medial projection on anterior margin, pinched or not; anterior edge with fine, entire marginal bead; surface relatively smooth, finely punctate; lines fine, continuous around coxal cavity; base distinctly concave. Mesosternum with lines continuous around coxal cavity. Metasternum with lines not continuous around mesocoxal cavity, extending onto surface of metasternum, variable in length; surface smooth, glossy or dull, finely punctate. Abdomen with lines continuous around metacoxal cavity, scattered fine punctures on terminal ventrites. Femur with marginal bead, angular in cross section; shortened, apex of meso- and metafemur often not visible from above. Tibia distinctly carinate on lateral edge. Tarsi with well-developed ventral pads on tarsomeres I-III; metatarsomere I length = metatarsomere II+III combined. Male of some species with pilose spot on first abdominal ventrite (e.g., A. clavicornis , A. lebasii ). Male genitalia with median lobe elongate and weakly hooked at apex.

Distribution. Aegithus is widespread in the Neotropics, with species native to Grenada and recently established on Hispaniola and Jamaica.

Larvae. Aegithus larvae were first diagnosed by Lacordaire (1832: 364; 1833: 89-90) for “ Erotylus surinamensis ”. Roberts (1958: 281) briefly diagnosed larvae of Aegithus meridionalis Crotch and Aegithus quadrinotatus Chevrolat. The following diagnosis is based on the full description of A. clavicornis larvae by Teixeira and Casari (1998), and direct study of A. lebasii larvae from Jamaica ( Fig. 44-45 ).

Body elongate, with dark tergites, covered with spicules, scoli, and aristate or simple setae. Head setose, with short setiferous slender spines or tubercles. Antennal length about half head width. Tergites of T2-A8 dorsally with 3 long, branched scoli on each side. Abdominal epipleurites with single, large, branched scoli; urogomphi short, about as long as an abdominal segment. Spiracles annular.

Remarks. Generic limits, relationships, and placement of some taxa remain problematic within Erotylini . Likewise, the historical practice of identifying taxa based solely on written descriptions has led to many species being placed in incorrect genera or to the production of incorrect synonyms. Previously cited characters used to define genera and subgenera often vary among species presently assigned to these taxa and lead to descriptions like the one above. Considering these daunting problems, some species are difficult to confidently place in some genera (e.g., Aegithus and Iphiclus ) and generic limits remain vague. A larger revisionary study with deep taxon sampling is needed to assess additional generic characters and resolve these tenuous generic limits.

Aegithus and Iphiclus are diverse mainland genera with few representatives naturally occurring in the West Indian fauna. Addressing mainland species to resolve generic limits is outside the scope of this work. Thus, traditional concepts of these genera and species placements were maintained.

Figures

Figure 2-11. Key characters. 2-3) Anterior view of head and pronotum. 2) Iphiclus suturalis. 3) Notaepytus flavitarsis. 4-5) Lateral habitus. 4) Aegithus clavicornis. 5) Iphiclus suturalis. 6-11) Dorsal habitus. 6) Aegithus clavicornis. 7) Aegithus lebasii. 8) Iphiclus guadeloupensis. 9) Iphiclus suturalis. 10) Cubyrus sapphirus. 11) Ischyrus quadripunctatus.

Figure 38-41. Aegithus spp., dorsal and ventral habitus. 38, 40) A. clavicornis. 39, 41) A. lebasii.

Figure 42-45. Aegithus spp., male genitalia and larva. 42) A. clavicornis. 43) A. lebasii. 44-45) A. lebasii larva, lateral and dorsal view. Genitalic scale line = 1 mm.