Adephaga (from Greek ?d?f????, adephagos, "gluttonous"), with more than 40,000 recorded species in 10 families, is a suborder of highly specialized beetles and the second largest suborder of the order Coleoptera. Members of this suborder are adephagans, a term which notably include ground beetles, tiger beetles, predacious diving beetles, and whirligig beetles. The majority of the species belong to the family of carabids, or ground beetles (Carabidae).
Adephagans have simple feelers with no pectination or clubs. The galea of the first maxilla usually consists of two segments. Adult adephagans have visible notopleural suture. The first visible abdominal sternum is completely separated by the hind coxae, which is one of the most easily recognizable traits of adephagans. There are 5 segments on each foot.
The transverse fold of the hindwing is near the wing tip. The median nervure ends at this fold, where it is joined by a cross nervure.
Adephagans have four malpighian tubules. Unlike in other beetles, yolk chambers alternate with egg chambers in the ovarian tubes of adephagans. The coiled, tubular testes consist of a single follicle; and the ovaries are polytrophic.
All families of adephagan have paired pygidial glands located postero-dorsally in the abdomen, which are used for secreting chemicals. The glands consist of complex invaginations of the cuticle lined with epidermal cells contiguous with the integument. The glands have no connection with the rectum and open on the eighth abdominal tergum.
Secretions pass from the secretory lobes, which are aggregations of secretory cell, through a tube to a reservoir lined with muscles. This reservoir then narrows to a tube leading to an opening valve. The secretory lobes differ structurally from a taxon to another: it may be elongate or oval, branched basally, apically or unbranched.
Delivery of glandular compounds
The secretion is realized in one of the following three manners:
- Oozing: if the gland is not muscle-lined, the discharge is limited in amount,
- Spraying: if the gland is muscle-lined, which is typically the case of carabids, the substances are ejected more or less forcefully,
- Crepitation: only associated with the Brachininae carabids and several related species. See bombardier beetle for a detailed description of the mechanism.
The secretion differ in the chemical constituents, according to the taxa. Gyrinids, for instance, secrete norsesquiterpenes such as gyrinidal, isogyrinidal, gyrinidione or gyrinidone. Dytiscids discharge aromatic aldehydes, esters and acids, especially benzoic acid. Carabids typically produce carboxylic acids, particularly formic acid, methacrylic acid and tiglic acid, but also aliphatic ketones, saturated esters, phenols, aromatic aldehydes and quinones. Accessory glands or modified structures are present in some taxa: the Dytiscidae and Hygrobiidae also possess paired prothoracic glands secreting steroids; and the Gyrinidae are unique in the extended shape of the external opening of the pygidial gland.
The function of many compounds remain unknown. Yet hypothesis have been advanced:
- Toxins or feed deterrent against predators. Some compounds indirectly play this role by easing the penetration of the deterrent into the predator's integument.
- Antimicrobial and antifungal agents (especially in Hydradephaga),
- A means to increase wetability of the integument (especially in Hydradephaga),
- Alarm pheromones (especially in Gyrinidae),
- Propellant on water surfaces (especially in Gyrinidae),
- Condition plant tissues associated with oviposition.
Distribution and habitat
Habitats range from caves to rainforest canopy and alpine habitats. The body forms of some are structurally modified for adaptation to habitats: members of the family gyrinidae live at the air-water interface, rhysodines in heartwood, paussine carabids in ant nests.
Most species are predators. Other less typical forms of feeding include: algophagy (family Haliplidae), seed-feeding (arpaline carabids), mycophagy (rhysodine carabids), snail-feeding (licinine and cychrine carabids). Some species are ectoparasitoids of insects (brachinine and lebiine carabids) or of millipedes (peleciine carabids).
Reproduction and larval stage
Some species are ovoviviparous, such as pseudomorphine carabids.
The larvae are active, with well-chitinized cuticle, often with elongate cerci and five-segmented legs, the foot-segment carrying t wo claws. Larvae have a fused labrum and no mandibular molae.
Adephagans diverged from their sister group in the late Permian, the most recent common ancestor of living adephagans probably existing in the early Triassic, around 240 million years ago. Both aquatic and terrestrial representatives of the suborder appear in fossil records of the late Triassic. The Jurassic fauna consisted of trachypachids, carabids, gyrinids, and haliplid-like forms. The familial and tribal diversification of the group spans the Mesozoic, with a few tribes radiating explosively during the Tertiary.
The phylogeny of adephagans is disputed. The group is usually divided into two main groups:
- The Geadephaga, comprising the two terrestrial families Carabidae and Trachypachidae (the Trachypachidae is sometimes considered a subfamily of the Carabidae), and
- The Hydradephaga, gathering all other families, which are aquatic. li>
This division is often criticized, as mounting evidence is pointing out that the two groups are not monophyletic.
List of subgroups of the order Coleoptera
- "Adephaga". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=109226.
- Adephaga Tree of Life
The Suborder Adephaga is a member of the Order Coleoptera. Here is the complete "parentage" of Adephaga:
- Domain: Eukaryota
Whittaker & Margulis,1978 - eukaryotes
- Kingdom: Animalia
C. Linnaeus, 1758 - animals
- Subkingdom: Bilateria
(Hatschek, 1888) Cavalier-Smith, 1983 - bilaterians
- Branch: Protostomia
Grobben, 1908 - protostomes
- Infrakingdom: Ecdysozoa
A.M.A. Aguinaldo et al., 1997 ex T. Cavalier-Smith, 1998 - ecdysozoans
- Superphylum: Panarthropoda
- Phylum: Arthropoda Latreille, 1829 - Arthropods
- Superphylum: Panarthropoda Cuvier
- Infrakingdom: Ecdysozoa A.M.A. Aguinaldo et al., 1997 ex T. Cavalier-Smith, 1998 - ecdysozoans
- Branch: Protostomia Grobben, 1908 - protostomes
- Subkingdom: Bilateria (Hatschek, 1888) Cavalier-Smith, 1983 - bilaterians
- Kingdom: Animalia C. Linnaeus, 1758 - animals
The Suborder Adephaga is further organized into finer groupings including:
- Family (9): Amphizoidae · Carabidae · Cicindelidae · Dytiscidae · Gyrinidae · Haliplidae · Hygrobiidae · Noteridae · Rhysodidae
Amphizoa is a genus of beetles, placed in its own family, Amphizoidae. It comprises six species, three from western North America and three from China. The vernacular name "trout-stream beetle" comes from the original finding of A. insolens and A. lecontei in high mountain streams, although other species occur at lower elevation. They are notable as a possible intermediate stage between terrestrial and aquatic beetles; while living in the water, they are not good swimmers and physically resemble ground beetles more than other types of water beetle. [more]
Ground beetles are a large, cosmopolitan family of beetles, Carabidae, with more than 40,000 species worldwide, approximately 2,000 of which are found in North America and 2,700 in Europe. [more]
The tiger beetles are a large group of beetles known for their aggressive predatory habits and running speed. The fastest species of tiger beetle can run at a speed of 9 km/h (5.6 mph), which, relative to its body length, is about 22 times the speed of former Olympic sprinter Michael Johnson, the equivalent of a human running at 480 miles per hour (770 km/h). As of 2005, about 2,600 species and subspecies were known, with the richest diversity in the Oriental (Indo-Malayan) region, followed by the Neotropics. [more]
Dytiscidae ? based on the Greek dytikos (d?t????), "able to dive" ? are the predaceous diving beetles, a family of water beetles. They are about 25 mm (one inch) long on average, though there is much variation between species. Dytiscus latissimus, the largest, can grow up to 45 mm long. Most are dark brown, blackish or dark olive in color with golden highlights in some subfamilies. They have short, but sharp mandibles. Immediately upon biting they deliver digestive enzymes. The larvae are commonly known as water tigers. The family has not been comprehensively cataloged since 1920, but is estimated to include about 4,000 species in over 160 genera. [more]
The whirligig beetles are a family (Gyrinidae) of water beetles that usually swim on the surface of the water if undisturbed, though they swim actively underwater when threatened. They get their common name from their habit of swimming rapidly in circles when alarmed, and are also notable for their divided eyes which are believed to enable them to see both above and below water. [more]
The Haliplidae are a family of water beetles who swim using an alternating motion of the legs. They are therefore clumsy in water (compared e.g. with the Dytiscidae or Hydrophilidae), and prefer to get around by crawling. The family consists of about 200 species in 5 genera, distributed wherever there is freshwater habitat; it is the only extant member of superfamily Haliploidea. They are also known as crawling water beetles or haliplids. [more]
Noteridae is a family of water beetles closely related to the Dytiscidae, and formerly classified with them. They are mainly distinguished by the presence of a distinctive "noterid platform" underneath, in the form of a plate between the second and third pair of legs. The family consists of about 230 species in 12 genera, and is found worldwide, more commonly in the tropics. They are sometimes referred to as burrowing water beetles. [more]
Rhysodidae (sometimes called wrinkled bark beetles) is a family of beetles, consisting of several hundred species in about 20 genera. [more]
At least 25 species and subspecies belong to the Family Rhysodidae.
More info about the Family Rhysodidae may be found here.
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