Clade for ARTHROPODA & ONYCHOPHORA
SEGMENTED PROTOSTOMIA (after Ruppert & Barnes 1994 p. 1052, Brusca & Brusca 1990 p. 683)
=========== ANNELIDA (segmented worms) | <<=OTHER PROTOSTOMIA==| ==O==== ONYCHOPHORA (velvet worms) =P==| ==R================================== TO ARTHROPODA ===>
(** plesiomorphic- a primitive state, not unique to clade): b) ventro-lateral appendages c) must molt to grow d) ectodermal cilia lost e) extensive hemocoel ('open' circulatory system), coeloms reduced f) heart with openings to hemocoel (ostia) | b) unique oral papillae c) lobopod limbs d) tracheal system b) two tagmata (head, trunk) c) calcification of cuticle d) fully segmental sclerites (body-wall cuticular plates) e) each body segment has 2 sclerites (dorsal tergum, ventral sternum) f) jointed appendages with intrinsic muscles g) complete loss of motile cilia/flagella (except some sperm) |
==A========= Arachnida (spiders, mites, scorpions, etc.) ==C==| ========= CHELICERATA ===========| ==X========= Merostomata (horseshoe crabs) | | | ===P============= Pycnogonida (sea spiders) | <<=| ===== TRILOBITOMORPHA ======================== (extinct trilobites) | | | | ====== Symphyla (symphylans) | | ==S==| | | | ====== Chilopoda (centipedes) | | ===Myriapoda======| =T==| | =========== Diplopoda (millipedes) | | | === UNIRAMIA==| ==Entognatha=== Collembola (springtails) | | | | | | ==Hexapoda====| == Thysanura (silverfish and firebrats) | | (Insecta) ==Ectognatha=| =M=| == to Pterygota (winged insects) =======> | == to CRUSTACEA ===========================================================>
(** plesiomorphic- a primitive state, not unique to clade): b) mouth lies before segment 1 embryologically c) segment #1 limbs= chelicerae (no antennae; may be pincer-like or fangs) b) 1st or 2nd abdominal segment modified as genital somite b) ovigers (unusual 3rd pair limbs) c) abdomen reduced or absent d) long, 9-segmented walking legs e) multiple pairs of gonopores on some/all legs f) loss of compound eyes b) loss of compound eyes b) abdominal limbs modified as book gills c) long, spiked telson b) segment #1 limbs= antennae c) 4 pair post-oral head segments with biramous limbs similar to thoracic limbs b) body dorso-ventrally flattened c) limbs of post-oral head segments similar to limbs of thorax (all with two branches, biramous?)** | b) 5 pair head appendages (2 pair antennae, 1 pair mandibles, 2 pair maxillae) c) body segment cuticle of 4 sclerites (tergum, 2 lateral pleura, sternum) d) mouth anterior to segment 3 in adult b) mandible is 'whole-limb' c) unique tracheal system d) uniramous limbs (exopodite lost) b) loss of compound eyes c) loss of palps on 1° & 2° maxillae d) repugnatorial glands b) loss of compound eyes c) loss of palps on 1° & 2° maxillae d) repugnatorial glands b) maxillipeds modified as raptorial poison fangs b) 3-segment thorax with limbs c) 11-segment abdomen, no limbs |
====1============================= Cl. Remipedia <<==C==| | ===3========================== Cl. Cephalocarida =2==| | ==5======================= Cl. Branchiopoda (fairy shrimp, water fleas, etc.) =4==| | ==7=================== Cl. Maxillopoda (copepod, ostracod, barnacle, etc.) ==6=| | ==8============== SubCl. Phyllocarida (Or. Leptostraca) =Mal=| | =====10====== SubCl. Hoplocarida (mantis shrimps) ==9=| | ==11= SupOr. Peracarida (mysids, amphipods, isopods, etc.) ==Eumal=| ==12= SupOr. Eucarida (krill, shrimps, lobsters, crabs, etc.)
(** plesiomorphic- a primitive state, not unique to clade): b) 2° antennae biramous c) mandible is simple (gnathobasic) d) sessile (non-stalked), compound eyes** e) many similar, biramous, phyllopodousthoracic limbs** f) telson with rami g) nauplius larvae b) raptorial mouth appendages c) segment #6= maxilliped d) many similar trunk segments (no trunk tagmata) with paddle-like biramous legs e) pre-antennal process f) eyes lost b) reduced number of body segments b) abdomen of 11 segments c) segment #5= leg-like d) compound eyes lost b) abdomen has fewer than 9 segments b) abdomen has fewer than 8 segments b) abdomen has fewer than 5 segments c) unique naupliar eyes & loss of lateral compound eyes |
b) abdomen of 7 segments + telson c) carapace covers head & thorax** d) 1° antennae biramous e) stalked eyes f) gills on thoracic limbs b) abdomen of 7 segments + telson** c) 2° maxilla like thoracic limbs** d) similar, phyllopodous thoracic limbs** b) thoracic limbs stenopodous c) long muscular abdomen d) telson lacks rami b) limbs of first 5 thoracic segments uniramous & subchelate c) thorax segment #2 with very large subchela d) moveable rostrum e) gills on pleopods b) thoracic oostegites form brood chamber c) pre-juvenile manca stage b) 3 pair maxillipeds (except euphausids) c) last 5 pair thoracic limbs uniramous (except euphausids) d) well-developed gills under carapace (except euphausids) e) brood eggs on pleopods (except euphausids) |
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Copyright © 2000 by A. Richard Palmer. All rights reserved.
(revised Jan. 18, 2000)