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Great Plains Research: A Journal of Natural and Social Sciences Great Plains Studies, Center for

August 1991

The Lucanidae and Passalidae (Insecta: Coleoptera) of Nebraska

Brett C. Ratcliffe University of Nebraska-Lincoln, [email protected]

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Ratcliffe, Brett C., "The Lucanidae and Passalidae (Insecta: Coleoptera) of Nebraska" (1991). Great Plains Research: A Journal of Natural and Social Sciences. 24. https://digitalcommons.unl.edu/greatplainsresearch/24

This Article is brought to you for free and open access by the Great Plains Studies, Center for at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Great Plains Research: A Journal of Natural and Social Sciences by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. THE LUCANIDAE AND PASSALIDAE (INSECTA: COLEOPTERA) OF NEBRASKA

Brett C. Ratcliffe

Systematics Research Collections, W436 Nebraska Hall University of Nebraska State Mweutn Lincoln, NE 68588-0514

Abstract. A faunal study of the five species of Lucanidae and one species of Passalidae that occur in Nebraska is presented. All of these species are near the extreme western limit of their geographic range in North Anterica, and five of the six species are reported from Nebraska for the first time. The treatment for each species consists of synonymy, description, general dism'bution, Nebraska locality records, temporal distribution in the state, remarks on identification, reference to larval desc@tions when available, and information about the biology and ecology of each species when known. Dism'bution maps, showing the Nebraska records, are given for each species. Habitus drawings of the adult of each species as well as line drawings illustrating larval characters are provided. A key to all the Nebmska species of Lucanidae is provided.

There is no need to be frightened. It is true some of the creatures are odd, but I find the situation rather heartening than otherwise. It gives one a feeling of confidence to see nature still busy with experiments, still dynamic, and not through nor satisfied because a Devonian fish managed to end as a two-legged character with a straw hat. ---Loren Eiseley The Ittuneme Journey

The Scarabaeoidea is a large, cosmopolitan superfamily of beetles comprised of the families Scarabaeidae, Lucanidae, and Passalidae. In Nebraska, there are 203 species in these three families: Scarabaeidae (197), Lucanidae (5), and Passalidae (1). The Scarabaeidae in the state were treated in detail by Ratcliffe (1991), and the remaining two families are reviewed here. The stag and passalid beetles in Nebraska have not been treated previously due in large measure to the fact that they have never before been recognized as occurring in Nebraska; five of the six species are here recorded from Nebraska for the first time and constitute new state records. 250 Great Plains Research Vol.1 No.2

All of these species are very near the westernmost limit of their geographic ranges. Because they are usually associated with eastern deciduous forests, a prairie state like Nebraska is not usually considered as having suitable habitat. Most of our species are found in extreme southeastern Nebraska where eastern deciduous forest is present in patches or as gallery forests along watercourses. There is also a significant lack of collecting in most of Nebraska, and so our knowledge of the state's insect fauna remains fragmentary at best. This lack of entomological information is even more pronounced when extended to species that are usually encountered only at lights or as a result of chopping apart rotted logs and stumps where they live.

Materials and Methods

The results of this study are based on the examination of all the specimens known to exist in the principal research collections in Nebraska. The majority of specimens come from the systematics research collections of the Division of Entomology of the University of Nebraska State Museum. These collections, numbering about 1.75 million specimens, are recognized as one of the top 20 collections in North America (Conference of Directors of Systematics Collections 1971; Fischer et al. 1975) and represent a century of data gathering in the prairie biome. The collection at Hastings College is small but contains important locality records. Conventional artificial keys to all the taxa involved are presented, and an attempt was made to utilize key characters that are consistently expressed and easily observed. The keys and descriptions are all augment- ed by illustrations to assist the reader in correctly identifying specimens. The illustrations consist of line drawings and habitus drawings on pebble board. Dot maps show county distributions for each species based on label data. Each genus and species-level taxon is introduced with its chronologi- cal, nomenclatural history. An abbreviated description of each species follows. To avoid subjectivity, a note on puncture size is important. Minute punctures are generally not seen with 12.5 X magnification but are easily seen with 50 X magnification. Small punctures are easily seen with 12.5 X magnification and can be seen with the unaided eye. Large punctures are easily seen without the aid of instruments. Remarks on the overall, and then Nebraska, distribution for each species is presented following the description. The actual locality data is followed by the temporal distribution. The "Remarks" section is divided into (a) distinguishing features of the adult, (b) reference to larval descriptions, and (c) life history and ecological information. Nebraska Stag Beetles 25 1

Key to the Families of Adult Scarabaeoidea in Nebraska

1. Antenna with segments of club flattened, capable of being closed together...... Scarabaeidae 1'. Antenna with segments of club usually not flattened, not capable of being tightly closed together ...... 2 2. Antenna straight or slightly curved. Elytra glossy black, deeply striated ...... Passalidae 2'. Antenna geniculate (except Cemchus). Elytra not deeply striate ...... Lucanidae

FAMILY LUCANIDAE

The lucanids, or stag beetles, consist of about 1,050 species occurring worldwide, with the richest species diversity in Asia (Benesh 1960). In the United States there are approximately 30 species in ten genera (Arnett 1968). Nebraska has five species, nearly all near the extreme western limit of their range. All five are here reported for the first time for Nebraska and constitute new state records. The most recent world catalog is that of Benesh (1960) wherein he recognized eight subfamilies, four of which occur in the United States (three in Nebraska) (Benesh 1960). The classification of the North American species is relatively stable. In a radical departure from established classifications, however, Howden and Lawrence (1974) proposed a significant rearranging of genera within subfamilies for the North American taxa, but it remains to be seen from a phylogenetic standpoint whether these realignments will be accepted. Their hypothesis has not yet been addressed. The Lucanidae is closely related to the Scarabaeidae and, along with the family Passalidae, forms the superfamily Scarabaeoidea. Unlike the Scarabaeidae, however, the members of the Lucanidae are unable to close the segments forming the club of the antenna. The antenna in most species is geniculate, or "elbowed," although in the Sinodendrinae and some Aesalinae it is straight. Most species are characterized by pronounced sexual dimorphism due to the increased development of the mandibles in the males. In some tropical species, the mandibles can easily exceed half the body length; and in a few species it is longer than the body (Fig. 1). The growth of the mandibles is allometric. Within a species, those males with greatly devel- oped mandibles are customarily referred to as male majors whereas those with small mandibles are called male minors. This kind of differential mandibular development is evident in Nebraska's three species in the Great Plains Research Vol.1 No.2

Figure. 1. Cyclommafus imperator Boileau from New Guinea. From Didier and Seguy 1953.

genera Lucanus and Dorcus and to a much lesser extent in the two species in Platycems and Ceruchus. Arrow (1951) discussed at length the morphology and possible rationale for large mandibles and horns. Very little is known of the habits of adult lucanids. They are often attracted to lights at night, and some species feed at sap flows from fluxing trees during the night. Adults of some of the smaller species have been taken feeding on flowers. The larvae, for the most part, live in and feed on decaying wood in rotting deciduous and coniferous trees. There are a few observations of larvae feeding on the roots of grasses and shrubs. In gestalt, the whitish, C-shaped larvae resemble those of Scarabaeidae, but in lucanids the anal opening is longitudinal or Y-shaped whereas in scarabs it is usually transverse or occasionally Y-shaped. Nebraska Stag Beetles 253

Key to the Species of Adult Lucanidae in Nebraska

Antenna straight ...... Ceruchus piceus (Weber) Antenna geniculate ...... 2 Elytra smooth or nearly so. Foretibia usually with 4 large teeth on lateral edge ...... 3 Elytra striate-punctate. Foretibia serrulate or with 4-6 small teeth on lateral edge ...... 4 Femora yellowish brown. Mandible of male with 1 tooth ...... Lucanus capreolus (L.) Femora piceous to black. Mandible of male with several teeth ...... Lucanus placidus Say Eye emarginate, with canthus interrupting anterior margin ...... Dorcus parallelus (Say) Eye entire, canthus absent ...... Platycerus virescens (Fabr.)

Key to the Species of Larval Lucanidae in Nebraska (after Ritcher 1966)

1. Thoracic spiracles with concavities of respiratory plates facing cephalad (Fig. 2). Trochanters of metathoracic legs each with stridulatory area consisting of a single, longitudinal row of short, transverse ridges (Figs. 3-4). Inner margin of left mandible (distad of molar area) with 1 or more teeth (Fig. 9). Raster with 2 patches of spine-like setae (Figs. 11-12) ...... 2 1'. Thoracic spiracles with concavities of respiratory plates facing caudoventrad or cephaloventrad. Trochanters of metathoracic legs each with stridulatory area consisting of a patch of small teeth or granules (Fig. 7). Inner margin of left mandible (distad of molar area) smooth, not toothed (Fig. 10). Raster without spine-like setae (Fig. 13) ...... Ceruchus piceus (Weber) 2. Trochanter of metathoracic leg with long, pointed, apical lobe (Fig. 4). Claws with 4-6 setae (Fig. 3) ...... Lucanus capreolus (L.)and placidus Say 2'. Trochanter of metathoracic leg swollen apically but lacking a strongly projecting lobe (Fig. 5). Claws with 2 setae ...... 3 3. Coxae of mesothoracic legs each with stridulatory area consisting of slightly curved, longitudinal row of subconical teeth posterior to which is a patch of small granules (Fig. 6) ...Dorcus parallelus (Say) 3'. Coxae of mesothoracic legs each with stridulatory area consisting of several oblique rows of subconical granules (Fig. 8) ...... Platycents virescens (Fabr.) Great Plains Research Vol.1 No.2

Figures. 2-13. Larval Lucanidae: (2) Dorcus parallelus, third stage larva (setae omitted); (3) Lucanus placidus, right mesothoracic leg; (4) Lucanus placidus, left mesothoracic leg; (5) Dorcus parallelus, left mesothoracic leg; (6) Dorcus parallelus, right mesothoracic leg; (7)Cenlchlls sp., left mesothoracic leg; (8) Plarycen~ssp., left mesothoracic leg; (9) Dorcusparallelus, dorsal view of left mandible; (10) Ceruchus piceus, dorsal view of left mandible; (11) Dorcus parallelus, venter of last abdominal segment; (12) Lucanus placidus, venter of last abdominal segment; (13) Ceruchus piceus, venter of last abdominal segment. From Ritcher (1966) by permission. Nebraska Stag Beetles 255

Subfamily AESALINAE

This diverse subfamily is comprised of five tribes (Benesh 1960). The Nicagini consists of one genus found in North America and Asia. The Platycerini contains four genera, three of which are restricted to California, Oregon, Washington, and British Columbia; the fourth genus, Platycems, is widespread in Asia, Europe, North Africa, and North America. The Ceruchini has one genus occurring in Europe, India, Asia and North America, while the single genus in the Ceratognathini is found in Australia and New Zealand. The Aesalini contains one genus found in Europe, Asia, and Mexico.

Genus Plarycm

Platycems Geoffroy 1762: 62. Systenocems Weise 1883: 93. Systenus Sharp and Muir 1912: 573.

Eight species are placed in the genus Plaiycems (Benesh 1960). Five of these species occur in the United States with one in Nebraska. The Holarctic species were revised by Benesh (1946). The larvae subsist in decomposing logs of generally soft-wooded, deciduous trees. Life cycles have not been established for each life stage although the length of the life cycle is apparently only one year. Benesh (1946) described the egg of one species, and Ritcher (1966) described the larva of another.

Plarycm virescens (Fabr.) (Figs. 8, 14, 17)

Lucanus virescens Fabricius 1775: 817. Lucanus quercus Weber 1801: 85. Lucanus securidens Say 1823: 249. Plaiycems scantoides Sturm 1843: 136. Platycents angustus Casey 1908: 280. Platycems iowanus Casey, 1908: 280. Platycems peregrinus Casey 1908: 280.

Description.--Length 7.6-12.0 mm; width across humeri 2.8-3.9 mm. Color piceous to black (most common), shining, occasionally with brassy or green reflection. Helzd: Surface completely punctate; punctures moderate in size, dense, frequently a little larger andlor confluent in females. Clypeal region 256 Great Plains Research Vol.1 No.2 strongly depressed with apex deeply and broadly emarginate in male, less so in female. Eyes entire, canthus absent. Mandibles in male stout, usually subequal to length of head, externally bisinuate, and curved dorsomedially toward apex; apex multidentate and with sparse, long, pale setae on inner edge; base with a strong tooth medially. Females with mandibles short, stout, curved medially toward acute apex; basal tooth reduced. Antenna geniculate. Pronofunt: Surface completely, densely punctate; punctures moderately large becoming a little larger and/or confluent in females, especially laterally. All margins bordered. Eljttra: Surface with 5 finely impressed striae between suture and humerus. Intervals and sides with large punctures. Legs: Foretibia serrulate.

Distribution.--Platycents virescens is a relatively abundant species in the northeastern portion of the United States east of the Mississippi River and in eastern Canada (Benesh 1946). Between the Mississippi River and the Rocky Mountains it is less abundant. It extends west as far as south- eastern Nebraska and is reported here as a NEW STATE RECORD.

Locality Records (Fig. 17).--12 Nebraska specimens examined. LANCASTER CO. (12): Lincoln, Roca.

Temporal Distribution.--April (7), May (4), June (1).

Remarks--The entire eyes in combination with the geniculate antennae, small size, and heavily punctate dorsal surface will serve to separate this species from other stag beetles in Nebraska. The larval stage is known but apparently has not been described. Ritcher (1966) described an Oregon species, Platycerus oregonensis Westwood. Adults and larvae can be found in rotting tree trunks and beneath bark. Adults have been seen feeding on the new shoots and buds of young pear trees (Riley 1870) and frequently on flowers such as those of blackberry (Dillon and Dillon 1961). Blatchley (1910) observed adult activity in Indiana between late March to late October. Hoffman (1937) recorded the duration of pupation as 11 days and 13 days for two specimens. The larvae feed on rotting wood, but their precise life history has never been worked out. Nebraska Stag Beetles

Figure. 14. PIaiycerus virescens (Fabr.). 258 Great Plains Research Vol.1 No.2

Genus Ceruchus

Ceruchus Macleay 1819: 115. Platycerus Latreille 1807: 133 (preoccupied). The genus Ceruchus is composed of seven species (Benesh 1960). Three species occur in North America, two in Asia, one in Europe, and one in India. A modern revision of the genus has not been done although the latest catalog by Benesh (1960) has stabilized the nomenclature. Of the North American species, one is found in the northeastern quadrant of the United States and in southeastern Canada while the other two species occur in California to Vancouver Island. The biology of these species is not very well known other than they live in rotting tree trunks and stumps.

Ceruchus piceus (Weber) (Figs. 7, 10, 13, 15, 17)

Lucanus piceus Weber 1801: 84. Tarandus amencanus Dejean 1837: 194. Plarycerus balbi Castelnau 1840: 174. Ceruchus quercicula Melsheimer 1843: 136 (nonzen nudunz). Ceruchus virginiensis Casey 1914: 372.

Description.--Length (excluding mandibles) 9.5-14.3 mm; width across humeri 3.9-5.1 mm. Color piceous to black, shining. Hend: Males with broad, deep pit in center of head, absent in females. Surface in males with large, umbilicate punctures behind eyes, on vertex, and in central depression; surface between eye and central depression with strong, cariniform, oblique rugae extending posterolaterally. Surface in females with large punctures; punctures dense, occasionally confluent, umbilicate. Eye in lateral view not interrupted by canthus. Mandibles in male majors a little shorter than length of head, stout, curved inwardly to pointed apex; 1 median tooth present at base and another strong, long tooth present at about middle; median tooth projects forward and upward from plane of mandibles; a sparse fringe of long, testaceous setae present between apex and median tooth. Male minors with similar, but smaller, mandibles. Mandibles in females short, stout, acute, with short submedian tooth and a narrow, blade-like molar area between tooth and base. Antenna simple, not geniculate. Pronoturn: Surface in males moderately punctate on disc, moderate in size, becoming slightly larger and denser laterally; surface in females with punctures a little larger and denser. Base completely margined. Elytra: Surface with 5 deeply impressed striae between suture Nebraska Stag Beetles

Figure. 15. Ceruchus piceus (Weber). 260 Great Plains Research Vol.1 No.2 and humerus. Intervals convex, moderately punctate, punctures small to mostly moderate in size (usually slightly larger in females). Sides punctate striate but not as distinctly. Legs: Profemora with large, oval patch of testaceous setae on dorsal surface at base. Protibia with 4-6 moderately large teeth on lateral edge with smaller serrations between teeth.

Distribution.--Ceruchus piceus is known (albeit imprecisely due to a lack of published records) from the northeastern United States and Ontario and Quebec in Canada (Wickham 1899; Blackwelder and Arnett 1974). The specimens from Nebraska are on the extreme western edge of the range of this species and represent a NEW STATE RECORD.

Locality Records (Fig. 17).--11 Nebraska specimens examined. NEMAHA CO. (9): Brownville; Southeast Nebraska (2).

Temporal Distribution.--April (9), May (1).

Remarks.--The straight antennae, relatively small size, and striate elytra will distinguish this species from all other lucanids in Nebraska. The larval stage was described in detail by Peterson (1960) and Ritcher (1966). Fuchs (1882) superficially described the pupa. Ceruchuspiceus is often locally abundant and yet little is known of its life history. Adults and larvae have been taken from rotting logs of elm, birch, and Norway pine (Hoffman 1937), oak (Blatchley 1910), and beech, chestnut, willow, birch, and black cherry (Felt 1906). The Nebraska specimens were taken from rotting oak trunks.

Subfamily DORCINAE

This large subfamily is divided into four tribes. The Prosopocoilini, with 18 genera, occurs in South America (5 genera), Africa (2 genera), and Asia (12 genera). The Rhaetulini is comprised of four genera occurring in Asia and India and one genus in Central and South America. The Dorcini contains six genera, all of which are strictly Asian except for Dorcus which occurs in North America, Europe, North Africa, and Asia. The Pseudodorcini has ten genera: one in Hawaii, two in Australia, one in South America, and six in Asia. Nebraska Stag Beetles

Genus DcKcus

Dorcus Macleay 1819: 111. Lucanus Castelnau 1840: 173 (in part). Dynodorcus Didier 1931: 197 (in part). The genus Dorcus contains 31 species. Most of the species occur in Asia and India although two species are found in southern Europe, two in the eastern United States, and one in Mexico (Benesh 1960). One of the US species extends into southeastern Nebraska. A modern treatment for all the species in the genus has not been undertaken; Benesh (1937) provided a relatively detailed synopsis of the US species. The most recent world catalogs are those of Didier and Seguy (1953) and Benesh (1960). Life history information for the US species is generally lacking although, like most other species, they are known to develop in rotting tree trunks. The larval stage has been described but apparently not reared in order to establish length of instars, parasites, or predators.

Doil.clcs parallelus (Say) (Figs. 2, 5, 6, 9, 11, 16, 17)

Lucanus parallelus Say 1823: 248. Lucanus voeti Schonherr 1817: 326 (nomen nudum). Lucanus oblongus de Charpentier 1825: 214. Dorcus costatus LeConte 1866: 380. Dorcus nanus Casey 1908: 278. Dorcus parallelus var. carnochani Angel1 1916: 70.

Description.--Length (excluding mandibles) 15.0-26.0 mm; width across humeri 6.4-10.9 mm. Color piceous to black, weakly shining. Head: Male majors with surface shagreened, moderately punctate; punctures small, becoming sparser posteriorly; male minors with punctures becoming very large anteriorly and laterally; females with surface densely, confluently punctate, punctures large and deep; vertex impunctate. Eye canthus, in lateral view, protrudes across anterior edge of eye. Mandibles in male majors each about 314 length of head, curved to acuminate apex, stout, with a large dorsal tooth projecting at about 45O inward and upward; male minors similar but mandibles variably smaller, a little more or less 213 length of head; females with mandibles short, about half length of head or less, dorsal surface weakly to distinctly concave and with a short median tooth on inner edge. Antennae geniculate. Pronotum: Male majors with surface weakly alutaceous, punctate; punctures small and moderate in Great Plains Research Vol.1 No.2

Figure. 16. Dorcus parallelus (Say). Nebraska Stag Beetles 263 density on disc, becoming large on sides and very large on basal and espe- cially lateral margins. Male minors with punctures larger and denser all over; females with surface coarsely punctate on disc and lateral thirds coarsely, confluently punctate. Base completely margined. Elytra: Surface punctate-striate. Striae impressed, densely punctate, punctures large, most confluent. Intervals weakly costate with sparse, moderate punctures. Anterior angle strongly dentiform. Legs: Anterior femur with 4-6 small, lateral teeth.

Distribution.--Dorcusparallelusis found in the northeastern United States from New York south to South Carolina and Tennessee to Indiana (Leng 1920). The Nebraska localities listed below constitute a NEW STATE RECORD. The oak and linden gallery forests in which this species occurs in Nebraska are clearly on the westernmost edge of the range of this beetle.

Locality Records (Fig. 17).--2 Nebraska specimens examined. DOUGLAS CO. (1): Omaha; OTOE CO. (1): Nebraska City.

Temporal Distribution.--June (2).

Figure. 17. Nebraska distribution map for P. virescens, C. piceus, and D. parallelus. 264 Great Plains Research Vol.1 No.2

Remarks.--The striate elytra in combination with geniculate antennae and the eye divided by a canthus will easily distinguish this species from other stag beetles in Nebraska. The larval stage was described by Ritcher (1966), and the male pupa was briefly mentioned and illustrated by Fuchs (1882). According to Ritcher (1966), Dorcus parallelus is a common eastern species. Dillon and Dillon (1961) indicated adults are readily attracted to lights and larvae can be found in the roots and stumps of decayed oak, linden, and maple trees. Apparently nothing else is known of its life history.

Subfamily LUCANINAE

This subfamily is divided into four tribes (Odontolabini, Lucanini, Rhyssonotini, and Chiasognathini) and thirteen genera (Benesh, 1960). Members of each of the two genera occurring in the Rhyssonotini are Australian whereas those in the two genera of Chiasognathini are South American. The three genera comprising the Odontolabini occur in India and Asia. The remaining six genera in the Lucanini are more generally distributed in Asia (primarily), India, Africa (two genera), and Europe and North America (sharing one genus, Lucanus).

Genus Lucanus

Lucanus Scopoli 1763: 1. Hexaphyllus Mulsant 1839: 119. Pseudolucanus Hope 1845: 30 (subgenus).

The genus Lucanus presently contains 50 species distributed in Asia, Europe, and North America (Benesh 1960). Most of the species occur in Asia while four species are found in the United States. Two species in the genus occur in Nebraska. The genus as a whole has not been the subject of a monograph. Keys to the US species can be found in some of the older literature, such as Fuchs (1882), Blatchley (1910), and Dillon and Dillon (1961). The most recent synoptic catalogs are those of Didier and Seguy (1953) and Benesh (1960)- In spite of the relative abundance across eastern North America of the two species that occur in Nebraska, surprisingly little is actually known of their life history. Ritcher (1966) indicated he was unable to distinguish between the larvae of these two species. The literature suggests that L. capreolus apparently develops in rotting stumps and logs (Dillon and Nebraska Stag Beetles 265

Dillon 1961; Arnett 1968) while the larvae of L. placidus seemingly feed on the roots of shrubs (Milne 1933).

The generic placement of capreolus and placidus has varied between Pseudolucanus (van Roon 1910; Leng 1920; Didier and Seguy 1953; Dillon and Dillon 1961; Arnett 1968; Blackwelder and Arnett 1974) to Lucanus (Benesh 1960; Ritcher 1966). Benesh is the most recent lucanid specialist (as differentiated from a compiler like Arnett or the Dillons), and so his generic placement is followed here.

Lucanus capreolus (L.) (Figs. 18, 21)

Scarabaeus capreolus Linnaeus 1763: 391. Lucanus duma Fabricius 1775: 2. Lucanus muticus Thunberg 1806: 205. Lucanus trigonus Thunberg 1806: 200. Pseudolucanus capreolus ab. nigricephalus Benesh 1938: 273.

Description.--Length (excluding mandibles) 20.0-36.0 mm; width across humeri 8.0-16.0 mm. Color light to dark reddish brown, femora yellowish brown, weakly shining. Head: Vertex sparsely to moderately punctate, punctures moderate in size. Frons and clypeus densely punctate (male minors) to densely rugopunctate (male majors); females with frons and clypeus coarsely rugopunctate. Eye canthus protrudes across anterior edge of eye in lateral view. Mandibles in male majors each subequal to length of head, curved medially to pointed apex, stout, and with a small median tooth at about anterior third; male minors similar but smaller; females with mandibles about half length of head, similar to those of male except with strong, dorsal ridge. Antenna geniculate. Pronotum: Small specimens with moderately dense, small punctures on disc, punctures becoming larger and denser laterally. Larger specimens similar but surface rugopunctate laterally. Base completely margined. Elytra: Surface completely, densely punctate, punctures small. Anterior angle rounded to weakly dentiform. Legs: Anterior femur normally with 4 lateral teeth.

Distribution.--Lucanus capreolus is known from Quebec and Ontario in Canada and the northeastern quadrant of the United States west to Nebraska and Kansas. Southeastern Nebraska is on the extreme western edge of its range. The specimens listed below represent a NEW STATE RECORD. Great Plains Research Vol.1 No.2

Figure. 18. Lucanus capreolus (L.). Nebraska Stag Beetles 267

Locality Records (Fig. 21).--69 Nebraska specimens examined. ADAMS CO. (18): no data; CASS CO. (1): Plattsmouth; DOUGLAS CO. (2): Omaha; GAGE CO. (1): Beatrice; JEFFERSON CO. (1): no data; LANCASTER CO. (38): Lincoln; RICHARDSON CO. (5): Indian Cave State Park; SALINE CO. (1): DeWitt; SARPY CO. (1): Schramm Park; SEWARD CO. (1): 7 mi. S. Garland.

Temporal Distribution.--May (3), June (12), July (51), August (2).

Remarks.--The relatively large size in combination with nonstriated elytra and yellowish brown femora will easily distinguish this species from all other Lucanidae in the state. The immature stages are known, having been taken from decaying logs and stumps. Ritcher (1966) indicated that he was unable to separate larval L. capreolus from either L. placidus or L. elophus. His description of L. placidus, therefore, also describes L. capreolus. In spite of the relative abundance of this handsome stag beetle, its life history appears not to have been studied and temains unknown. Like other stags, the eggs are laid in rotting trees where the larvae then devel- op. Adults may be found on sap flows or at sugared baits, and they are readily attracted to lights.

Lucanus placidus Say (Figs. 3, 4, 12, 19, 21) Lucanus placidus Say 1825: 202. Lucanus rupicapra Dejean 1837: 193 (nonten nudunt). Lucanus lentus Castelnau 1840: 171. Description.--Length (excluding mandibles) 19.0-32.0 mm; width across humeri 8.4-14.0 mm. Color usually black, occasionally dark reddish brown, pronotum weakly shining, elytra opaque. Head: Vertex moderately punctate, becoming densely punctate on frons and clypeus in males or coarsely rugopunctate in females; punctures small and moderately large, mixed. In lateral view, eye canthus interrupts anterior margin of eye. Mandibles in male majors subequal in length to head, curved medially to pointed apex, cariniform on dorsolateral edge, with 5-7 small teeth on median edge; mandibles in male minors smaller, usually with 2-4 small, medial teeth; mandibles in females short, stout, with 1 medial tooth. Antenna geniculate. Pronoturn: Surface along midline usually moderately punctate, becoming densely punctate on disc and confluently punctate or rugopunctate on sides; punctures moderately large, deep. Base completely margined. Elytra: Surface finely shagreened, densely punctate in males, 268 Great Plains Research Vol.1 No.2 confluently punctate to rugopunctate in females; punctures moderately large. Anterior angle rounded. Legs: Anterior femora normally with 4 lateral teeth, broader in females, and with a large, oval patch of golden setae on dorsal surface at base.

Distribution.--Lucanusplac~dusis a relatively abundant species in Ontario, Canada, and in Illinois, Indiana, Kentucky, Michigan and Pennsylvania in the United States (Blackwelder and Arnett, 1974). It is also known from Michigan, Ohio, Missouri, Alabama, Kansas, Iowa, Oklahoma, New Mexico, New York, and Minnesota (Milne, 1933). Like most other eastern species of Lucanidae, Nebraska is at the westernmost edge of the range of L. placidus. Considering the customary occurrence of stag beetles only in Nebraska's eastern deciduous forests, the records throughout much of Nebraska are surprising. The specimens listed below are a NEW STATE RECORD.

Locality Records (Fig. 21).--13 Nebraska specimens examined. BROWN CO. (1): Long Pine; CASS CO. (1): Cedar Creek; CHERRY CO. (1): Dewey Lake; DOUGLAS CO. (1): Waterloo; FRANKLIN CO. (1): no data; HOLT CO. (1): Spencer Dam; HOWARD CO. (1): St. Paul; MADISON CO. (1): Meadow Grove; NUCKOLLS CO. (3): no data; RICHARDSON CO. (1): Indian Cave State Park; SALINE CO. (1): Crete.

Temporal Distribution.--May (I), June (9), July (2), August (1).

Remarks--This species may be separated from all other stag beetles in Nebraska by its large size, presence of 4-7 teeth on each mandible of the males, and by the presence of an oval patch of golden tomentum at the base of the profemora on the dorsal surface. The larval stage was described by Ritcher (1966) who was unable to distinguish between L. placidus and L. capreolus. Milne (1933) described and illustrated the pupal stage. Based on collecting records, this species is not abundant in Nebraska. This may reflect, however, a simple lack of collecting effort for these insects. What little is known of the biology of this species was provided by Milne (1933). Adult beetles, after emergence from the subterranean pupal cell, tunnel to just beneath the surface of the ground usually during the afternoon preceding escape from the ground. Emergence from the ground always occurred between dusk and 10 PM. Milne never found specimens after 10:30 PM either at lights, clinging to vegetation, or having re-entered the ground. He noted the beetles he was studying were excep- tionally abundant in a localized, sandy area. Nebraska Stag Beetles

Figure. 19. Lucanus placidus Say. 270 Great Plains Research Vol.1 No.2

Specimens were never observed to oviposit, but first instar larvae were found in grass sod. Later instar larvae were commonly encountered at a depth of about 30 cm feeding on the roots of live oaks, Virginia creeper, Boston ivy, and other shrubs. As many as 140 adults were taken on the night of maximum emergence from a plot of two square yards! Milne postulated a four-year life cycle for the Toronto locality. Shenefelt and Simkover (1950) reported larvae occasionally damaging roots of conifers in tree nurseries in Wisconsin. Hoffman (1937) conducted partially successful rearing experiments and found pupation to average 29.6 days (range 29-30 days, 7 individuals). One adult female lived 489 days.

FAMILY PASSALIDAE

The primarily pantropical family Passalidae contains about 500 species (Schuster 1978). The last world catalog for the family is that of Hincks and Dibb (1935; 1958). About 285 species occur in the New World (Blackwelder 1944), and apparently only one species now inhabits the United States, including Nebraska (Schuster 1983). Reyes-Castillo (1970) provided the most recent synoptic treatment of adult morphology and grouping of American genera. He divided the Passalidae into two subfami- lies, the Aulacocyclinae (Oriental and Australian regions) and Passalinae (pantropical). The Passalinae were divided into the tribes Proculini (Neotropical) and Passalini (pantropical). Schuster and Reyes-Castillo (1981) presented a key to larvae for individuals from 21 of the 22 New World genera. So far as is known, most species live in rotting wood. The most widely distributed species are those of tropical lowlands below 1500 m while a few species (mostly Proculini) are found above 2800 m. Most species occur in moist forests although some species occur in dry forests and even in the nests of desert ants (Schuster 1978). All life stages of Passalidae are found in galleries excavated by the adults where both adults and larvae feed on wood pulp. Most species live in hardwood, but some are found in conifers or even in palms. These beetles have been variously referred to as social, subsocial, or communal. Reyes-Castillo and Halffter (1984) favor the subsocial description because of parental cooperation and care of young as well as sibling cooperation to care for younger individuals of the same generation. Larvae and adults both stridulate, and adults have been observed to prepare food for first instar larvae and to help with preparation of a pupal cell. Scarabaeoid larvae taken from rotting logs can be immediately recognized as Passalidae because they appear to have only two pair of legs; Nebraska Stag Beetles 27 1 the rnetathoracic leg is greatly reduced (Figs. 22, 23). As many as ten species of passalid have reportedly been found in a single rotting log (Luederwaldt 1931). Larval identification is greatly facilitated by the facts that larvae are usually associated with adults and that the galleries of each different species do not impinge on each other.

WCaenius dkjuncncs (Illiger) (Figs. 20-29)

Scarabaeus intemptus Linnaeus 1764: 35 (name preoccupied). Passalus disjunctus Illiger 1800: 78. Passalus comutus Fabricius 1801: 256. Passalus distinctus Weber 1801: 79. Passalus bos Kuwert 1891: 171.

Description.--Length 26.4-37.0 mm; width across humeri 9.4-12.8 mm. Color black, shining. Head: Surface strongly excavated between eyes, rim of excavation toothed above each eye, center of excavation with prominent, hooked horn; horn vertical for half its length, bent abruptly forward for remainder of length, apex triangular. Clypeus foreshortened, very narrow. Antenna 10-segmented, apical 3 segments enlarged. Mandibles large, 314 length of head, laterally compressed, with 1 tooth on dorsal edge subapi- ally and with 3 apical teeth. Pronorum: Surface sparsely, minutely punctate; disc with deep, longitudinal sulcus. Base margined except narrowly at center. Elytra: Surface with 5 punctate, grooved striae between suture and humerus and 5 grooved striae between humerus and lateral edge. Intervals convex, sparsely and minutely punctate. Legs: Foretibia slender with 7-9 lateral teeth.

Distribution.--0dontotaeniusdisjuncrus is confined to the deciduous forests of the eastern United States from central Florida to Massachusetts and west to eastern Texas, Oklahoma, Kansas, Nebraska, and southeastern Minnesota (Schuster 1983). In Nebraska, it is known from the southeast- ern corner of the state.

Locality Records (Fig. 21).--15 Nebraska specimens examined. CASS CO. (6): Plattsmouth; RICHARDSON CO. (6): Falls City, Rulo; No data (3).

Temporal Distribution.--March (6), April (6). In actuality, specimens can be found nearly any time of the year by inspecting the logs in which they live. Hibernation occurs in the Nebraska population due to cold winters. Great Plains Research Vol.1 No.2

Remarks.--The relatively large body size, strongly grooved elytra, and black color in combination with the elongate, subparallel, dorso-ventrally compressed body form will distinguish this beetle from all others in the state. The larval stage was described by Hayes (1929), Peterson (1960), Ritcher (1966; Figs. 22-29), and Schuster and Reyes-Castillo (1981). Also known as the "patent leather beetle," "horned passalus," or "Betsy beetle," 0. disjunchts has been studied extensively because of its interesting habits, large size, and availability. The observations of Gray (1946) are the most complete and are summarized here. Passalid beetles make tunnels in hardwood logs of nearly all species of trees except pine and cedar. The availability of down timber and its degree of decomposition are more important for passalid activity than the species of hardwood. The number of years a log is habitable by passalid beetles is variable and depends on moisture conditions, size of the log, and whether the wood remains suitable for food. Tunneling is difficult until a log begins to rot, and so most logs are suitable at two to five years old. Gray observed one large oak log in North Carolina inhabited by passalids for over ten years. Tunnels generally follow the grain of the wood, and tunnels can routinely attain a length of ten feet. Adults are present in the logs at all seasons while eggs, larvae, and pupae are found only during the warmer months. Even though possessing fully developed metathoracic wings, this species rarely takes flight. Gray conducted experiments to induce it to fly, but failed to get it to do so. Hunter and Jump (1964) observed actual flight. The wings are also used in stridulation. Stridulation in adults was accurately described by Babb (1901) who disproved the statements of Riley (1872), LeConte (1878), and Ohaus (1900) that the elytra were used in sound production. A pair of rasp-like, oval areas on the fifth abdominal tergite are rubbed against sclerotized folds of the hind wings when the abdomen is raised. A sharp squeaking noise is made. Hermann and Anderson (1974) discussed the complex wing-folding in this species. Larval stridulatory organs consist of the greatly reduced metathoracic leg (shaped like a bear paw; Fig. 23) which is vibrated rapidly over a striated area on the mesocoxa. The sound produced is feeble but can be distinctly heard if the larva is held close to the ear. Adults rarely stridulate except when disturbed. On being disturbed, however, they will emit loud squeaks that may serve as a signal of danger to others in the colony. Larval stridulation, on the other hand, is more or less continuous and may serve to keep adults informed as to the location of the young. Adults may live at least two years and possibly longer. The life cycle from egg to adult takes 2.5-3.0 months to complete, a relatively short time Nebraska Stag Beetles

Figure. 20. Odontotaenit~sdisjzinctr~s (Illiger). 274 Great Plains Research Vol.1 No.2 for so large a beetle. There is only one generation per year, and immature stages can be found only during portions of the summer. Oviposition occurs primarily in May and June. Egg-laying for each female continues over a period of two or more weeks. Eggs are always laid in the midst of finely chewed, decayed wood that has been previously pre- pared by the adults. Eggs are bright red when laid, gradually turn dark green, and hatch in about 16 days. New eggs are ovoid and average 3.2 x 2.4 mm. At the time of hatching, the average size has increased to 3.7 x 3.2 mm as a result of water absorption. Normally, 20-35 eggs are laid although 60 were found in one batch. Since the eggs are not all laid at the same time, there is a considerable difference in hatching time, which leads to considerable variation in larval size in any one colony. There are three larval instars. First instar larvae are most abundant in June and early July, and the length of the stadium averages 12-18 days. First instar larvae are unable to survive unless they eat wood that has been prepared for them by the adults. Even after extensive experimentation by Pearse et al. (1936), the reasons for this remain unclear. Unlike termites, 0. disjunctus does not depend on wood-digesting protozoans in its gut. Newly hatched larvae remain close to the egg nest, but as they become older they extend their wanderings in the tunnels. Larvae are white upon

.,".,", LUCANUS capreolus

ODONTOTAENIUS • • ma * disjunctus

Figure. 21. Nebraska distribution map for L. capreoll~s,L. placidlis, and 0. disjuncfi~s. Nebraska Stag Beetles

Figures. 22-29. Odontotaenius disjuncm larval features: (22) third stage larvae; (23) left mesothoracic and metathoracic (arrow) legs; (24) epipharynx; (25) dorsal view of left mandible; (26) ventral view of left mandible; (27) head; (28) dorsal view of left maxilla and labium; (29) venter of last two abdominal segments. From Ritcher (1966) by permission. Great Plains Research Vol.1 No.2 hatching but take on their characteristic bluish tinge after feeding for a short while. The adults are extremely active and extend the tunnels as the larvae grow. Adults line the galleries with finely chewed pulp which seems to be the only source of food for the larvae. Second instar larvae are found in late June and throughout July, and 10-15 days for this stage is typical. Third instar larvae are found in July and most of August, and they average 25 days during the stadium. There is a brief prepupal stage lasting about five days during which the larva stops feeding, becomes fat in appearance, and wanders about looking for a place to pupate. A cocoon of mud or wood chips is customarily built around the prepupa by the adults, and the prepupa rolls over and over to compact the wood chips and to smooth the inner surface (Miller 1932). The pupal stage lasts 10-12 days. Upon emergence from the pupal case, teneral adults remain in their pupal cases for several days because sclerotization of the integument takes place slowly. Some adults go from reddish black to black in a few weeks while in others it may take several months. Zelia vertebrafa Say (Diptera: Tachinidae) is a serious parasite of larval 0. disjunctus. The larvae of this fly, rarely observed before mid-July, feed inside juvenile passalids. No larva parasitized by the fly ever becomes an adult. Gray noted infestations typically ran from 33-60% of a passalid colony. He also observed that many other scarab larvae lived in the same log as the passalid, but that they were not parasitized by this fly. Larvae of the nematode, Chondronenla passali (Leidy) infect the abdominal cavity of third instar larvae, pupae, and especially adults of 0. disjunctus (Pearse ef al. 1936; Gray 1946; Nickle and Pilitt 1969). As many as 4,260 larval nematodes were found in a single adult beetle, and the average number of nematodes in a single beetle at any season of the year was 471 (Pearse et al. 1936). Adults of the nematode apparently live free in the surrounding moist, decayed wood and grass (Christie and Chitwood 1931). Nothing in the literature suggests what adult beetle mortality is as a result of nematode infection. Numerous species of mites are associated with adult 0. disjuncnts. Some may possibly be injurious while others may be phoretic commensals. At present, mite relationships with this passalid remain unclear.

Conclusions

The Lucanidae and Passalidae occurring in Nebraska are eastern species at the westernmost extent of their ranges. All are forest-adapted species trying to survive on the edge of the largely inhospitable habitat of Nebraska's grasslands. Platycerus virescens, Ceruchus Piceus, Dorcus Nebraska Stag Beetles 277 parallelus, and Odontotanius disjuncnts are restricted to the eastern deciduous forests found in extreme eastern Nebraska. This is due to their narrower ecological requirements for suitable climate and forest type. However, the sate is dissected by riverbottom forests that provided natural pathways for some forest-adapted species to enter the plains. It is these forested corridors that have provided westward dispersal routes for Lucanus capreolus and L. placidus in Nebraska. These two species apparently have broader ecological tolerances and have dispersed into areas only marginally "forested." In Nebraska, scarab beetles associated with eastern deciduous forests comprise 25% of the Scarabaeidae found in the state (Ratcliffe 1990). Most of these are found in the eastern third of the state, and many of these are in gallery forests that extend well into areas of former tallgrass prairie. All of the lucanids and passalids in Nebraska show the same pattern of exploitation of floodplain prairie and forest corridors for dispersal. Acknowledgments

I thank Mark Marcuson (Scientific Illustrator, University of Nebraska State Museum) for the habitus drawings of the adults of the Nebraska species. Gail Littrell, also University of Nebraska State Museum, did the word processing. The Oregon State University Press is acknowledged for its permission to use larval illustrations from Ritcher (1966).

References

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