The Lucanidae, Are a Scarabs Is the Number of Segments in the Family Within the Superfamily Club

Morphology

The scarab-like beetles: An important character that is used Scarabaeoidea to differentiate lucanids from other Th e stag beetles, the Lucanidae, are a scarabs is the number of segments in the family within the superfamily club. In the Australian Lucanidae the Scarabaeoidea. Members of this antennal club is composed of three to superfamily generally have lamellate seven segments and the antennae have antennae. Th e terminal segments of this 10 segments in total. The antennae vary highly developed organ form a club, from being geniculate (elbowed) to non- composed of plates known as lamellae. Th e geniculate and have a relatively long typical scarab lamellae can be compressed scape (first segment of the antenna). The into a ball or spread out in a fan-like genus Lissapterus has at the most only a manner. In the Lucanidae the antennal slightly pectinate antennal club whereas club is quite variable and is in some species in the genus Ceratognathus the comb- fl abellate rather than lamellate. like segments are quite long (especially in males) and movable, but cannot be The main morphological characters of closed fully into a compact club. the Australian Lucanidae A very conspicuous character of Body elongate, some robust, 5–72 mm these beetles is their sexual dimorphism. Head prognathous, males often with Males of many species have large, ornate prominent mandibles, some branched mandibles, while females have smaller Antennae with long scape, often and very simple ones. The mandibles of geniculate, three to seven loose male Lucanidae are often used in combat segmented club that cannot be with rival males, especially when completely closed attempting to mate with a nearby female Eyes entire or with a partial or complete or in self-defence against would-be canthus predators. Usually it is quite easy to Labrum and clypeus usually fused to distinguish the sexes through their frons mandibles, although in some cases the Scutellum visible smallest males look very much like Abdomen with five visible ventrites females and several species show only Legs relatively long and slender, protibia minimal sexual dimorphism. The sexes well developed are indistinguishable externally in some Tarsal formula 5–5–5 genera (e.g. Figulus). Usually brown or black, some species Another well-known character in have lighter dorsal patterns, some this family is the allometric development vividly metallic.

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Schematic map of a non-specific stag beetle (based on Ryssonotus nebulosus), dorsal view. 1. Frons, 2. Pronotum, 2a. Disc, 3. Scutellum, 4. Suture, 5. Elytra, 6. Hind-or metafemur, 7. Hind- or metatarsus, 8. Hind- or metatibia, 9. Mesotarsus, 10. Mesotibia, 11. Mesofemur, 12. Mesothorax, 13. Fore- or profemur, 14. Fore- or protibia, 15. Fore- or protarsus, 16. Maxillary palp, 17. Antenna, 18. Mandible, 19. Eye, 20. Vertex. Drawing: Esther Bolz.

Schematic map of the head of a non-specific Schematic map of the head of a non-specific stag beetle (based on Lucaninae female), stag beetle (based on Lucaninae female), dorsal ventral view. 1. Labrum, 2. Mentum, 3. Gula view. 1. Frons, 2. Vertex, 3. Mandible, 4. Labrum, (throat), 4. Gena (cheek), 5. Eye, 6. Canthus, 5. Canthus, 6. Eye, 7. Postocular margin, 7. Antenna, 8. Galea (outer lobe of the maxilla), 8. Preocular margin, 9. Galea (outer lobe of the 9. Mandible, 10. Maxillary palp, 11. Labial palp. maxilla). Drawing: Esther Bolz, after Holloway. Drawing: Esther Bolz after Holloway.

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Antenna of Syndesus cornutus. Drawing: Esther Bolz. Antenna of a Lamprima sp. Drawing: Esther Bolz.

of the male mandible (the size of the mandible is proportional to the size of the body), which has often confounded taxonomists. The marked differences in the teeth of the mandibles may depend on the overall body size of the male. In this book, where this occurs, we will simply refer to small males of a species as ‘minor males’ and large males as ‘major males’. Australian lucanids are mostly black, dark brown or, in the case of the subfamily Lampriminae, a vivid colour with a metallic lustre. The scutellum is always visible, although sometimes it may be rather small.

Antenna of a male Ceratognathus sp. Drawing: Esther Bolz.

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Stag beetles have always interested beetles) and Bolboceratinae coleopterists, amateurs and professionals (Geotrupidae, earth-boring dung alike. Many of these beetles have beetles) (Smith et al. 2006). Glaresidae spectacular shapes, their larvae lead are small, 2.5–6.5 mm long beetles that cryptic lives and, in most species, people don’t occur in Australia and practically do not commonly encounter the adults nothing is known about their biology. in their habitats. The Lampriminae and Some lucanid beetles have secluded, many of the tropical Lucaninae are long life cycles, spent mostly inside or splendidly coloured while others show under decaying, fungus-ridden logs or an amazing variety in the male standing dead and rotting trees. mandibular size and structure – these are Development from egg to adult can take some of the outstanding characteristics several years, depending on the species of this family which made these beetles and local circumstances. Lucanid larvae, so popular. Their aesthetic appeal and like most other wood-eating insects, the rarity of some species represent great must employ the help of microorganisms value to collectors. In several cultures to digest food with high cellulose the stag beetle represents a mythical or content. Recent studies have shown that mystical element and some important female lucanid beetles possess microbe- representations of it can be found already storing organs (mycangia) containing in Renaissance art (e.g. Dürer’s famous microorganisms closely related to drawing of the European stag beetle). xylose-fermenting yeasts (Tanahashi Undoubtedly, the study of this beetle et al. 2010). After laying an egg, the female family has great scientific importance. discharges some of these microorganisms The family Lucanidae consists of on and around it, thus leaving a digestion scarab type beetles belonging to the aiding ‘starter pack’ for the offspring superfamily Scarabaeoidea. In the past (Fremlin 2015). So far this research has this family was considered to be the most focused only on European and Japanese primitive family within the Scarabaeoidea lucanid species – the Australian lucanid (Lawrence and Newton 1995). More fauna has yet to be investigated. recent research, however, proposes that As the developing larva grows, it the Glaresidae (glaresid beetles) are the moults several times. The stages between most primitive family of scarabs and moults are known as instars. Stag beetle places the Lucanidae between Glaresidae larvae have three instars. Once the larva and Trogidae (skin or hide beetles) and reaches its full size, it pupates. For in the same clade with Passalidae (bess pupation to happen, the larva must first

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make a cavity (pupal chamber) within apparatus on the mid and hind coxae of the rotting wood or in the soil where it the legs and by the large fleshy pads on developed. Pupal duration is usually either side of the vertical or Y-shaped several weeks or a month depending on anal opening. the species, and the newly emerged adult Stag beetles have exarate pupae. The needs to harden and will remain in the appendages are free and quite pupal chamber for a similar amount of recognisable, but movement is limited to time or for many months if the time of the abdominal segments. The pupa may year or conditions are not appropriate. wriggle a little when irritated, but Young beetles with unhardened otherwise remains inactive. exoskeletons and immature colouring While larvae consume considerable are known as teneral adults. amounts of rotten wood and have even The lucanid larva has typical been found in rotten structural timber scarabaeoid characteristics as it appears (Lawrence 1981a), it is believed that as the usual, whitish, C-shaped scarab adults of many species eat very little or ‘curl grub’. The head is strongly don’t eat at all. This assumption is based sclerotised and the mandibles are stout on the study of some species’ reduced and strong, adapted to feed on decaying mouthparts and studies of their wood. alimentary canal. Adults of some Lucanid larvae can stridulate, Lamprima species feed on plant although this may not be readily secretions and possibly nectar and observed and is often not audible to the certainly do feed on soft fruit when kept human ear. It is thought that stridulation in captivity. Other species (e.g. helps to establish the presence of a larva Cacostomus squamosus) are known to to other larvae in a population and may feed on the exuding sap of injured trees. help in promoting avoidance behaviour. For a large percentage of Australian Lucanid larvae can be distinguished Lucanidae, nothing much is known from the larvae of other scarab families about adult feeding nor breeding habits. by the location of the stridulatory The biology of the Australian stag beetles

A characteristic stag beetle larva. Photo: PZ. The sclerotised head of a stag beetle larva. Photo: PZ.

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The large fleshy pads at the posterior of a stag beetle larva. Photo: GH. is not thoroughly researched although captivity. This topic is discussed with some species are successfully bred in more details on pages 212–215.

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The Australian fauna shows definitive This supercontinent started to break up connections to the fauna of the ancient in the early Jurassic, ~180 million years Gondwana and also to Asia. The ago. The parts that separated moved adjective ‘Gondwanan’ is often used in apart, taking with them their flora and biogeography, the study of the fauna, like travellers on gigantic rafts, distribution of species and ecosystems dispersing over huge areas. Many in geographic space and through aspects of Southern Hemisphere geological time. Gondwana, the ancient, biogeography refer to patterns of enormous continent, included most of distribution of living organisms, the landmasses in today’s Southern especially when these seem to be related Hemisphere, including Antarctica, and are restricted to two or more of the South America, Australia and also some now discontinuous regions that were others that are now north of the Equator. once part of Gondwana.

A stag beetle that can fly: Lamprima latreillii Macleay, 1819. Photo: PZ

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The discovery of two extant species Ancestors of some of our stag of Sphaenognathus (p. 72) and one beetle species belonging to genera extinct, fossil Syndesus (p. 67) species are Dorculus, Dorcus, Prosopocoilus and perhaps the best examples (in Lucanidae) Figulus could have arrived from Asia of our Gondwanan origins. through the connecting expanses of Biogeographic connections between dry land. Australia and Asia are still poorly Some of our endemic species are understood, although the plate tectonics good fliers but others, mainly those that of the Indo-Pacific region is now well exist in much more specialised habitats described. During the Pleistocene and lead cryptic lives, have lost the (2 588 000 to 11 700 years ago), extended ability to fly; examples are Lissapterus periods of glaciation caused decreases of and Lissotes, which live under or within sea levels by more than 100 m in decaying timber. Australasia. During these periods, Kim and Farrell (2015) recently landbridges formed between South-East researched lucanid relationships and Asia and northern Australia. Migration divergence time estimates and how of plants and animals was possible Gondwanan break-up effected throughout the epoch. biogeographical developments.

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