Color profile: Disabled Composite Default screen Neotropical species of Dietta (Coleoptera: Leiodidae: Leiodinae: Estadiini) 810 Stewart B Peck,1 Joyce Cook Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada The Canadian Entomologist 135: 775 – 810 (2003) Abstract—The genus Dietta Sharp, 1876 was previously known in the Neotropics only by D. sharpi Matthews, 1887 from Panama. This paper describes a new subge- nus of Dietta, Mesodietta subgen. nov., occurring in Middle America and northern South America west of the Andes, composed of D.(M.) sharpi Matthews and eight additional new species: D.(M.) esmeraldas sp. nov., D.(M.) latidens sp. nov., D.(M.) lobidens sp. nov., D.(M.) mesoamerica sp. nov., D.(M.) mexicanus sp. nov., D.(M.) puntarenas sp. nov., D.(M.) rectispina sp. nov., and D.(M). uncinata sp. nov. Additionally, seven new species of Dietta, subgenus Dietta, are described: D.(D.) argentinensis sp. nov., D.(D.) atlantica sp. nov., D.(D.) geraisensis sp. nov., D.(D.) guiana sp. nov., D.(D.) huanuco sp. nov., D.(D.) pauloensis sp. nov., and D.(D.) sucumbios sp. nov. Peck SB, Cook J. 2003. Les espèces néotropicales de Dietta (Coleoptera : Leiodidae : Leiodinae : Estadiini). The Canadian Entomologist 135 : 775–810. Résumé—Jusqu’à maintenant, on ne connaissait qu’une seule espèce néotropicale du genre Dietta Sharp, 1876 soit D. sharpi Matthews, 1887 du Panama. On trouvera ici la description d’un nouveau sous-genre de Dietta, Mesodietta subgen. nov., qui habite l’Amérique centrale et le nord de l’Amérique du Sud, à l’ouest des Andes et qui comprend D. (M.) sharpi Matthews, ainsi que huit espèces additionnelles nou- velles : D. (M.) esmeraldas sp. nov., D. (M.) latidens sp. nov., D. (M.) lobidens sp. nov., D. (M.) mesoamerica sp. nov., D. (M.) mexicanus sp. nov., D. (M.) puntarenas sp. nov., D.(M.) rectispina sp. nov. et D. (M.) uncinata sp. nov. On trouvera égale- ment la description de sept nouvelles espèces de Dietta, sous-genre Dietta : D. (D.) argentinensis sp. nov., D. (D.) atlantica sp. nov., D. (D.) geraisensis sp. nov., D. (D.) guiana sp.nov., D. (D.) huanuco sp. nov., D. (D.) pauloensis sp. nov. et D. (D.) sucumbios sp. nov. [Traduit par la Rédaction] Introduction The genus Dietta is an unusual and poorly known component of the beetle fauna of the Neotropics. During general sorting of medium-sized to small beetles, they are most often first thought to be small scarab beetles, in spite of the non-scarab shape of the antennae. They have also been thought to be unusual silphids (where the genus Dietta was once classified), allied to the genus Nicrophorus Fabricius. The conspicuous indicator that they belong in the Leiodidae is that the eighth antennal segment is smaller than the seventh and ninth, the common hallmark of most Leiodidae (Fig. 1). The genus Dietta is based on Dietta sperata Sharp, 1876 from Australia. The genus Dietta has a tropical, southern subtropical, and warm temperate distribution (Newton 1998), and is known from Australia (3 species), Africa and Madagascar (16 species, Peck 2003), and 1 Corresponding author (e-mail: [email protected]). 775 J:\ent\ent13506\N02-111.vp November 17, 2003 11:40:36 AM Color profile: Disabled Composite Default screen 776 THE CANADIAN ENTOMOLOGIST November/December 2003 FIGURE 1. Dietta (Mesodietta) rectispina. Habitus. Body length 4.6 mm. the Neotropics. This suggests a “Gondwanan” distribution pattern and may hint at a Gondwana origin. Only one species of Dietta was previously known from the Neotropics: Dietta sharpi Matthews, 1887 described from Volcan Chiriqui, western Panama. This paper describes 15 additional species from the Neotropics. Undoubtedly, many more species remain to be discovered. Most Neotropical collections of the genus Dietta are from moist or wet lowland or montane tropical and subtropical forests. Only one spe- cies from the Neotropics is known from strongly seasonal and open savanna or scrub forest habitats, which is where the genus Dietta is known to occur abundantly in south- ern Africa and Australia (Peck 2003; SB Peck, unpublished data). In the past, speci- mens were only rarely collected, and these were at lights or in Malaise traps. The extensive use of large-area flight-intercept traps (FIT) (Peck and Davies 1980) has dra- matically increased the number of Neotropical specimens now available for study to nearly 600. Intensive sampling in Costa Rica, for the Instituto Nacional de J:\ent\ent13506\N02-111.vp November 17, 2003 11:40:38 AM Color profile: Disabled Composite Default screen Volume 135 THE CANADIAN ENTOMOLOGIST 777 Biodiversidad (INBIO) countrywide species diversity study, has produced the largest number of specimens. Estadiine beetles have never been found on any items that could be considered to be their food or that of their larvae, and larvae are unknown. It is assumed that both adults and larvae feed on subterranean fungi, because of the robust digging legs and large and strong mandibles of the adults, and the fact that the seemingly closely related Sogdini leiodines are known to feed on such fungi (Newton 1998). It is also of note that females are collected much more frequently in flight-intercept traps than males, and that males are not known for several species. Newton (1998) clarified the systematic position of the genus Dietta. The genus is now placed in the leiodid subfamily Leiodinae, forming the sole genus in the tribe Estadiini. In general appearance, the genus Dietta most closely resembles members of the tribe Sogdini; this tribe contains eight genera, including the relatively common north temperate genus Hydnobius Schmidt. The tribe Estadiini is characterized by hav- ing a deeply emarginate labrum; tarsal formula 5-5-5 in both sexes, with the first tarsomere being much smaller than the second; and the mesocoxae being widely sepa- rated by a distance about equal to their length. The sexes are usually difficult to sepa- rate externally. Dissection is often needed to confirm the sex of a specimen. This study has found that males of most species have tufts of fine pale setae on the undersides of some pro- and meso-tarsal segments, and these are not found in the females. The body lengths of the Neotropical species range from about 3 to 5 mm. Previous work and this study have shown that the most useful characters to sepa- rate the species are (i) the patterns of teeth on the inner edges of the mandibles, (ii) the shape and position of teeth on the metathoracic trochanter and tibia, and (iii) the shape of the median lobe of the aedeagus and its internal armature and parameres. We have not been able to find a sclerotized spermatheca. Material and methods Five hundred and ninety-seven specimens of Estadiini from Mexico, Central America, and South America were examined. Males were dissected, the genitalia mounted in Euparal medium on microslides, and then pinned with the specimens from which they originated. Drawings were traced from microprojector images, then inked on mylar drawing paper. Measurements were made from dry specimens with a linear ocular micrometer in a binocular microscope. Pronotal length was measured on the dor- sal midline. Elytral length was measured laterally from base to apex (chord of the arc). Total length is given as pronotal length plus elytral length. Greatest width was measured dorsally at the widest point of the two closed elytra. The following acronyms are used to indicate source or depository of specimens: BMNH British Museum (Natural History), London, United Kingdom CMNH Carnegie Museum of Natural History, Pittsburgh, Pennsylvannia, United States of America CMNC Canadian Museum of Nature, Ottawa, Ontario, Canada FMNH Field Museum of Natural History, Chicago, Illinois, United States of America FSCA Florida State Collection of Arthropods, Gainesville, Florida, United States of America INBIO Instituto Nacional de Biodiversidad, Santo Domingo, Costa Rica JMMC Jean-Michel Maes collection, Leon, Nicaragua SEMC Snow Entomology Museum, University of Kansas Museum of Natural His- tory, Lawrence, Kansas, United States of America J:\ent\ent13506\N02-111.vp November 17, 2003 11:40:38 AM Color profile: Disabled Composite Default screen 778 THE CANADIAN ENTOMOLOGIST November/December 2003 TABLE 1. Character polarization of Dietta species grouped by continent. Character Plesiomorphic state Apomorphic states 1. Mandibles: basal row of small teeth Absent (0) Present (1) 2. Antennal segments 7, 9, and 10 Sparsely setose (0) Segment 10 densely setose (1); segments 7, 9, and 10 densely setose (2) 3. Length of antennal segment 11 Equal to or greater Less than width (1) than width (0) 4. Clypeus Heavily sclerotized, Thin and pale (1) dark (0) 5. Apex of prosternal process Narrow (0) Triangular (1); pentagonal (2) 6. Procoxal cavities Widely open (0) Narrowly open (1); narrowly closed (2); strongly closed (3) 7. Hypomeral processes Not fused to prosternal Fused to prosternal process (1) process (0) 8. Aedeagus median lobe Entire (0) Bifurcated (1) 9. Parameres Short (0) Elongate (1) 10. Armature of internal sac Setae (0) Sclerotized teeth (1) NOTE: Outgroup is Hydnobius matthewsi Crotch. TABLE 2. Character matrix of Dietta species grouped by continents. Character* 12345678910 Outgroup 0 0 0 0000000 South America 0 0 1 1100001 Australia 0 0 1 111000? Africa 0 1 1 112000? Central America 1 2 0 0231110 NOTE: 0, plesiomorphic state; 1, 2, or 3, apomorphic states; ?, missing data. * Characters: 1, mandibles: basal row of small teeth; 2, antennal segments 7, 9, and 10; 3, length of antennal segment 11; 4, clypeus; 5, apex of prosternal process; 6, procoxal cavities; 7, hypomeral processes; 8, aedeagus median lobe; 9, parameres; 10, armature of internal sac. MZSP Museum of Zoology, University of São Paulo, São Paulo, Brazil SBPC Stewart B Peck Collection, Ottawa, Ontario, Canada TAMU TexasA&MUniversity, College Station, Texas, United States of America USNM United States National Museum, Washington, District of Columbia, United States of America Characters and character states used for the phylogenetic analyses are provided (Tables 1, 3).