Thorax of Apterygota (similar to Prothorax of Pterygota) spiracle NOTUM or TERGUM anapleurite coxapleurite coxa coxal articulation sternopleurite Anteriad (head points this way) STERNUM Modifications of the PROTHORAX: defense, offense, & competition pronotal shield (Blattodea) elongate prothorax (Mantodea & Raphidioptera) prothorax camouflage & defense protection prothoracic extensions (Hemiptera: Membracidae) thorn ant mimic mimic prey capture sexual selection (Coleoptera: Scarabaeidae) 1
The Pterothorax (the wing-bearing thorax): Meso- & Metathoraces prothoracic wing?? Paleodictyoptera Carboniferous, 325 mya Tergum of basic Pterygota mesothorax metathorax (PROTHORAX) PRIMARY SEGMENTATION MESOTHORAX ACROTERGITE PRESCUTUM SCUTUM SCUTELLUM POSTNOTUM PRESCUTUM antecostal suture WING BASE NOTUM (= acrotergite of metathorax) antecostal suture METATHORAX POSTNOTUM (ABDOMEN) (developmentally, this is the acrotergite of the first abdominal segment) 2
Sternum of basic Pterygota Mesothorax (morphology is not very consistent) (Prothorax) PRESTERNUM SPINASTERNUM (= SPINA) PRIMARY SEGMENTATION BASISTERNUM STERNELLUM sternal pit (or furcal pit) (Metathorax) spinal pit Pleuron of basic Pterygota PROTHORAX acrotergite basalare sclerite pleural wing process pleural coxal process MESOTHORAX primary segmentation SCUTUM epimeron episternum METATHORAX postnotum = (acrotergite of metathorax) wing base subalare sclerite pleural suture trochantin coxal segment of leg PRESTERNUM BASISTERNUM STERNELLUM sternal pit spinal pit and SPINASTERNUM 3
Cross-section of pterothorax longitudinal flight muscles TERGUM WING dorso-ventral (tergo-sternal) flight muscles sternal pit spinal pit sternal pits phragma primary segmentation pleural suture pleural apophysis sternal apophysis sterno-pleural muscles pleural wing process sternal apophysis Sternal flight-muscle modifications longitudinal flight muscles spinal apophysis Fusion of pterothoracic components shades of red = prothorax shades of blue = mesothorax shades of magenta = metathorax shades of green = abdominal Unitized pterothorax of Hymenoptera Unitized pterothorax of Diptera (Tipulidae) MESOTHORAX PRESCUTUM PROTHORAX SCUTUM SCUT- ELLUM METATHORAX ABDOMEN haltere 4
Thoracic changes due to secondary aptery CASTE polymorphism: Formicidae SEASONAL polymorphism: Aphidae SEXUAL dimorphism: BALANCED polymorphism: tussock moth Gryllidae (Gryllus firmus) hind wing Secondary aptery within orders [note: never in Odonata] Blattodea (cockroaches) Phasmatodea (stick insects) Gromphadorhina portentosa Timema spp. Dermaptera (earwigs) Hemiptera (true bugs) Mesoveliidae Hemimerina Arixeniina Forficulina 5
Secondary aptery of entire orders Mallophaga Mantophasmatodea Siphonaptera (fleas) Notoptera Anoplura Psocodea Phthiraptera (but only if Phthiraptera is considered an order) Psocoptera Grylloblattodea The insect leg (generalized Orthoptera) femur tibia trochanter male Aukland Tree Weta leg of Weta tarsus (with 4 tarsomeres) coxa tendency toward fusion 1 2 3 4 plantulae pretarsus Significance of multiple tarsomeres: 1 5 1 tendency toward fusion with thorax 6
subcoxa femur tibia tarsus tergum epicoxa (forms wing hinge? subcoxa wing exite coxa pretarsus 3 rd leg of Machilis showing intrinsic & extrinsic muscles trochanter coxa trochanter exites patella Reconstruction of ancestral insect leg (after Kukalová-Peck 1987) prefemur femur tibia pretarsus tarsus The insect foot (pretarsus) extensor tendon ultimate tarsomere arolium aroliar pad unguis (ungues) pulvillus (pulvilli) auxilium (auxilia) unguitractor plate unguitractor tendon (from femur or tibia) Blow fly (Calliphoridae: Diptera) Grasshopper (Orthoptera) 7
Plecoptera Leg modifications Unspecialized (homonomous) More specialized (heteronomous) Coleoptera (harlequin beetle) Muscoid Diptera (legless) 8