Ento-301 Lecture

Autapomorphy

Uniquely derived character

Synapomorphy

Shared derived character

Symplesiomorphy

Shared ancestral character

Monophyletic group

A group of organisms which includes the most recent common ancestor of all its members and all of the descendants of that most recent common ancestor.

Paraphyletic Group

A group of organisms which includes the most recent common ancestor of all of its members, but not all of the descendants of that most recent common ancestor

Polyphyletic Group

A group of organisms which does not include the most recent common ancestor of those organisms; the ancestor does not possess the character shared by members of the group

Tagmosis

Amalgamation of segments into functional units

Sclerite

A plate on the body wall surrounded by membrane or sutures

Tergum

Dorsal plate, tergite

Sternum

Ventral plate, sternite

Pleuron

Side plate, pleurite

Pregenital segments

First 7 abdominal segments; similar in structure

Genital segments

Abdominal segments 8 and 9

Postgenital segments

Abdominal segments 10 and 11

Remigium

The main part of the wing that is powered by thoracic muscles

Clavus

Anal area + Jugal area

Fold-lines

The line in which the wings can be folded

Flexion-lines

Lines on which the wings flex during flight

Axillary area

Muscle attachment site

6 parts of the head

1. Preantennal (ocular)

2. Antennal

3. Labral

4. Mandibular

5. Maxillary

6. Labial

What are the two functional units of the head?

1. Cephalic sensory

2. Mouthparts

Tentorium

The four apodemes that meet internally to form a brace for the head.

5 parts of the mouth

1. Labrum

2. Hypopharynx

3. Mandibles

4. Maxillae

5. Labium

Protura

What is the only hexapod without antennae?

Protostomia

Develops mouth first

Ecdysozoa

Develops anus first

Ecdysozoans

Arthropods belong to this clade.

Panarthropoda

Animals with paired segmental ventrolateral appendages.

Tardigrada (water bears)

Onychophora (Velvet Worms)

Arthropoda

The three Phyla of Panarthroda

Body divided into at least two tagmata.

All panarthropods have these.

Chelicerata & Mandibulata

Two extant Monophyletic groups of Arthropoda.

Artiopoda

The extinct group of Arthropoda that included Trilobites.

Permian-Triassic extinction events.

When Artiopoda went extinct.

Chelicerata

• Pycnogonida – sea spiders

• Euchelicerata

  • Xiphosura – horseshoe crabs

  • Arachnida – spiders, mites, scorpions

Myriapoda

• Chilopoda – centipedes

• Diplopoda – millipedes

• Pauropoda

• Symphyla 

“Crustacea”

• Number of groups varies

• Paraphyletic grade

• Active area of research

• Ostracoda - seed shrimp

• Malacostraca - crabs, shrimps, lobsters

• Copepoda - copepods

• Thecostraca – barnacles

• Branchiopoda – brine shrimps

• Remipedia – likely sister to Hexapoda

Order Protura

• ~500 species worldwide

• Soil dwelling

• No eyes, no antennae, no tentorium, no cerci

• Front legs enlarged, with many sensilla (serve role of antennae)

• Anamorphic development – segments added posteriorly during development

Order Protura

1. no compound eyes 

2. no antennae

3. prognathous (mouthparts directed forward)

4. pseudoculus on head - probably remnants of antennae, thought to be humidity receptors

5. anamorphosis (abdominal segments added with each molt)

6. no cerci

7. styli present on abdominal segments I, II, and III

8. adult abdomen with 12 segments* 

Order Collembola

• ~6,000 species

• 4-segmented legs

• 6-segmented abdomen with a jumping organ (furcula and retinaculum)

• Leaf litter (detritivores)

• One of the most abundant animals in the world (~100,000 per cubic meter)

Order Collembola

1. rudimentary eyes or ocelli often present, 

2. antennae present 

3. often hypognathous 

4. epimorphosis (abdominal segments not added at molts)

5.  legs with 4 segments

   • coxa, trochanter, femur, tibio-tarsus 

6. abdomen 6-segmented and without cerci

7. Specialized abdominal appendages: 

   • collophore or ventral tube on segment 1

   • retinaculum on segment 3:  a hook that holds the furcula 

   • furcula on segment 4: acts as a spring 

Hypogastruridae 

• Collembola

• 1^st  thoracic segment is distinct 

– Visible dorsally 

– With setae 

• Furcula often reduced or lacking 

Isotomidae

• Collembola

• 1^st  thoracic segment  not distinct: 

– Often not visible dorsally 

– Without dorsal setae

Sminthuridae

• Collembola

• • Globular body with fused abdominal segments 

  • Antennae longer than head (“rabbit”)

  • Developed furcula and “eyes” present

  
  

Diplura

• ~800 species worldwide

• No eyes, no tentorium, two prominent cerci (either long and filiform or short and forcep-like), moniliform antennae

• Herbivorous or predaceous

Order Diplura

1. no compound eyes 

2. prognathous

3. epimorphosis 

4. adult abdomen with 11 apparent segments

5. cerci present

6. Abdominal segments 2-7 with styli 

7. 2 tarsal claws

Major characteristics of the Class Insecta

• Typically with ocelli and compound eyes

•  Ectognathous (external) mouthparts

•  Loss of musculature in the antennal flagellum

•  Primitively 11-segmented abdomen with gonopores on segment 8 (female) and 9 (male)

•  Well-developed tracheal system with spiracles

•  Larval/nymphal development epimorphic

Apterygota

Primitive and paraphyletic insect group including two wingless orders; Archaeognatha and Zygentoma.

Archaeognatha

• Jumping bristletails

• ~450 species worldwide

• Two extant families: Machilidae and Meinertellidae

• Living fossil

• Under bark, in litter, and in rock crevices,

• Feed on algae, lichens, and vegetable debris

• Indirect sperm transfer

Zygentoma

• Silverfish or firebrat

• ~550 species worldwide

• Five extant families

• Sister to Pterygota

• Omnivorous (some can digest cellulose)

• Indirect sperm transfer

Palaeoptera

Unable to fold wings flat over abdomen

Neoptera

“new wing”: wings capable of being folded back against their abdomen at rest, with wing articulations that derives from separate movable sclerites in the wing base.

Palaeoptera

Flight muscles attached directly to wing bases.

Neoptera

Flight muscles compress and expand the thorax.

“Basal Ephemeroptera” Hypothesis

The phylogenetic hypothesis that has Ephemeroptera as the Basal group and Odonata and Neoptera branching off from a common ancestor.

“Basal Odonata” Hypothesis

The phylogenetic hypothesis that has Odonata as the Basal group and Ephemeroptera and Neoptera branching off from a common ancestor.

“Palaeoptera” Hypothesis

The phylogenetic hypothesis that has Palaeoptera as the Basal group and Neoptera branching off from a shared common ancestor. This is the one supported by DNA evidence.

Ephemeroptera

1) 2 pairs of wings (usually), both membranous 

2) short, bristle-like antennae as adults

3) adults don't feed (mouthparts vestigial)

4) abdomen 10 segmented with 2 or 3 long caudal filaments (cerci + median caudal filament)

5) immatures are aquatic (naiads: hemimetabolous) and have abdominal gills

Lentic

Inhabiting still waters

Lotic

Inhabiting moving waters

Benthic

Inhabiting lowest zone of water, near the bottom.

Odonata

• 2 pairs membranous wings 

• antenna short and style-like

• adult mouthparts biting/chewing - all stages predaceous

• strong, active fliers, with meso- and metathorax enlarged and strengthened to house the large flight muscles

• immatures are naiads (hemimetabolous)

• Mobile head with large compound eyes and three ocelli

• Four wings elongate, many-veined, membranous

• Males have secondary genitalia

• Nymphs aquatic with up to 20 instars

• Nymphs have modified labium for capturing prey

Polyneoptera

• Superorder Dictyoptera

  • Order Blattodea (cockroaches and termites)

  • Order Mantodea (praying mantises)

• Order Orthoptera (grasshoppers, crickets, katydids)

• Order Dermaptera (earwigs)

• Order Embioptera (web-spinners)

• Order Plecoptera (stoneflies)

• Order Grylloblattodea (ice-crawlers)^{[note 1]}

• Order Mantophasmatodea (gladiators)^{[note 1]}

• Order Phasmatodea (stick and leaf insects)

• Order Zoraptera (angel insects)

Dictyoptera

• Superorder consisting of Mantodea (mantis) and Blattodea (cockroach and termite)

• Proventriculus has six internal, longitudinal folds (plicae) each possessing sclerites with teeth

Synapomorphy

A shared trait that evolved from a common ancestor.

Phasmatodea

• Cylindrical stick-like or flattened leaf-like

  • tarsi usually 5-segmented

• Prognathous, mandibulate

• Fore wings form leathery tegmina; hind wings broad with toughened fore margin (if present)

• Often wingless

• Elongate legs

  • Ovipositor short and concealed

• Cerci one-segmented

  • Biting/chewing mouthparts; herbivores

Autotomy

When an animal sheds a body part, often as a defense mechanism.

Myrmecochory

• Seed dispersal by ants

• Seeds have food bodies called elaiosomes

• Chemically attractive

• Phasmatodean eggs carried by ants

Embiidina

• Elongate, cylindrical

• Prognathous, biting mouthparts

• No ocelli

• Wingless in all females

• Basal fore tarsus swollen with silk gland

• Cerci two-segmented

Plecoptera

• Fore and hind wings nearly equal in size

• At rest, wings partly wrap abdomen and extend beyond abdominal apex

• Abdomen soft with filamentous cerci

• Immature aquatic

• Abdominal gills

Grylloblattodea

• Found only at high elevations in the mountains of China, Siberia, Japan, western United States and Canada, Altai and Sayan mountain ranges

• Some species are cave dwellers

• eyes small or absent

• wingless

• slender and elongate, pale and pubescent

• antennae long and filiform, 23-45 segments

• female with sword-shaped ovipositor

• cerci long, 5- or 8-segmented

• Prognathous

• stout coxa adapted for running

Mantophasmatodea

• Newest order of insect discovered 

• Smallest order with 8 described species

• Hypognathous

• Long antennae

• Wingless

• Fore and mid legs raptorial

• Endemic to South Africa and Namibia

Zoraptera

• Small, termite-like

• Gregarious lifestyle, with individuals living in colonies up to about 120 individuals

• Polymorphism in populations; with blind, apterous individuals dominating during colony life, but populations produce eyed alates (individuals with wings) for dispersal and founding new colonies

• biting/chewing mouthparts

• 2 pairs of membranous wings with very reduced venation sometimes present

• antennae moniliform

• tarsi are 2-segmented

• cerci are present

Dermaptera

• Elongate and flattened

• Prognathous 

• Antennae short to moderate

• Fore wings modified to leathery tegmina

• Hind wings semi-circular

• Cerci modified as forceps

• Mostly omnivorous

• Maternal care

  • Egg care

  • Nymphal care

  • Defense

  • Providing food

Proventriculus

A muscular part of an insect's digestive system that connects the crop to the stomach. 

Mantodea

• Head small, mobile, triangular

• Large compound eyes

• Elongated prothorax

• Fore legs raptorial

• Ootheca papery or cardboard-like in texture

• External male genitalia asymmetrical

Blattodea

• Antennae slender, filiform

• Pronotum oval, shield-like, covering much of head and thorax

• Legs adapted for running; tarsi 5-segmented

• Front wings thickened; hind wings membranous, pleated

• Cerci short, multi-segmented

• Hardened capsule-like oothecae (egg case)

• Viviparity

• Maternal care

  • Extreme case: Thorax porcellana from India, nymphs feed on mother’s haemolymph

Termitoidae

Termites used to be in its own order, Isoptera, but recent studies have confirmed that they are simply unusual eusocial cockroaches, thus it was reduced to epifamily…

Isoptera (not an order)

• two pairs of membranous wings, if present, approximately equal in size and shape and folding flat over body.  

• wings shed - break off along a basal, weakened line

• cerci very short

• eusocial, with castes

• Primary reproductives: queen and king

• Supplementary reproductives: potentially reproductive, but with arrested development

• Sterile: workers and soldiers

• Nymphs: developmental instars of reproductives

• Larvae: instars of sterile lineages
  

Physogastry

A condition where an arthropod's abdomen becomes greatly enlarged and membranous.

Trichonympha

The protozoans found in the gut of termites to help digest certain materials.

Trophallaxis

Anal fluid fed upon by other members of the colony.

Mid Ordovician Period

Hexapoda’s First Common Ancestor developed around this time.

Late Ordovician Period

Protura and Collembola’s common ancestor developed around this time.

Mid to Late Ordovician Period

Diplura and Insecta’s common ancestor developed around this time.

Phenotypic Plasticity

An ability of a single genotype to produce different phenotypes in response to environmental conditions.

Aposematism

The advertising by an animal to potential predators that it is not worth attacking or eating. This unprofitability may consist of any defenses which make the prey difficult to kill and eat, such as toxicity, venom, foul taste or smell, sharp spines, or aggressive nature. These advertising signals may take the form of conspicuous coloration, sounds, odours, or other perceivable characteristics.

Cibarium

A pouchy space in front of the mouth cavity of some insects, used to store and chew food.