Clade for ARTHROPODA & ONYCHOPHORA
SEGMENTED PROTOSTOMIA (after Ruppert & Barnes'94 p. 1052, Brusca & Brusca'90 p. 683)
=========== ANNELIDA (segmented worms)
|
<<=OTHER PROTOSTOMIA==| ==O==== ONYCHOPHORA (velvet worms)
=P==|
==R================================== to ARTHROPODA ===>
P- a) elongate body of many similar segments**, b) ventro-lateral appendages, c) growth by molting, d) ectodermal cilia lost
CHELICERATA: a) two tagmata (cephalothorax without distinct head, abdomen)**, b) mouth lies before first segment embryologically, c) segment #1 limbs= chelicerae (no antennae; may be pincer-like or fangs)
C (Crustacea): a) 1st antennae uniramous**, b) 2nd antennae biramous, c) mandible is simple (gnathobasic), d) sessile (non-stalked), compound eyes**, e) many similar, biramous, phyllopodous thoracic limbs**, f) telson with rami, g) nauplius larvae
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Copyright © 1998 by A. Richard Palmer. All rights reserved. (revised April 4, 1998)
O- a) external segmentation suppressed, b) unique oral papillae, c) lobopod limbs, d) tracheal system
R- a) lateral compound eyes, 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)
Phylum ARTHROPODA (tree/traits: Brusca & Brusca 1990 p. 485, 538, 589, 598, 659, 683, 691; taxa in FULL UPPER CASE indicate the four arthropod subphyla)
SUB-PHYLUM: CLASS:
==A========= Arachnida (spiders, mites, scorpions, etc.)
==C===|
=========CHELICERATA============| ==X========= Merostomata (horseshoe crabs)
| |
| ==P=============== Pycnogonida (sea spiders)
|
<<=| =====TRILOBITOMORPHA========================== (extinct trilobites)
| |
| | ==== Thysanura (silverfish and firebrats)
| | ==Insecta==|
| | | ==== Pterygota (winged insects)
=T==| ==Hexapoda===|
| | =============== Collembola (springtails)
| ==UNIRAMIA====|
| | | ========== Chilopoda (centipedes)
| | ===Myriapoda======|
=M==| ========== Diplopoda (millipedes)
|
= to CRUSTACEA ===========================================================>
*Traits supporting each clade (** plesiomorphic- a primitive state, not unique to clade):
C: a) cephalothorax carapace shield, b) 1st or 2nd abdominal segment modified as genital somite
P: a) pre-oral proboscis, b) ovigers (unusual 3rd pair limbs), c) abdomen reduced or absent, d) 9-segmented walking legs, e) multiple pairs of gonopores on some or all legs, f) loss of compound eyes
A: a) abdominal limbs reduced, lost or modified as spinnerets, b) loss of compound eyes
X: a) enlarged cephalothorax with large shield, b) abdominal limbs modified as book gills, c) long, spiked telson
T: a) mouth lies before second segment embryologically, b) segment #1 limbs= antennae, c) 4 pair post-oral head segments with limbs similar to thoracic limbs
TRILOBITOMORPHA: a) 3 tagmata (cephalon, thorax, pygidium), b) body dorso-ventrally flattened, c) limbs of post-oral head segments similar to limbs of thorax (all biramous)**
M (Mandibulata): a) 2 tagmata (head, trunk of many similar segments)**, 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)
UNIRAMIA: a) 2nd antennae lost, b) mandible is 'whole-limb', c) unique tracheal system, d) uniramous limbs
Hexapoda: a) 2nd maxillae fuse as labium, b) 3-segment thorax with limbs, c) 11-segment abdomen without limbs
Myriapoda: a) loss of compound eyes, b) loss of palps on 1st and 2nd maxillae, c) repugnatorial glands
CRUSTACEA: a) 1st antennae uniramous**, b) 2nd antennae biramous, c) mandible is simple (gnathobasic), d) sessile (non-stalked), compound eyes**, e) many similar, biramous, phyllopodous thoracic limbs, f) telson with rami, g) nauplius larvae
Subphylum CRUSTACEA (tree/traits as for Arthropoda)
====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=|
Mal= Cl. Malacostraca | ==11= SupOr. Peracarida (mysids, amphipods, isopods, etc.)
==Eumal=|
==12= SupOr. Eucarida (krill, shrimps, lobsters, crabs, etc.)
Eumal= SubCl. Eumalacostraca
*Traits supporting each clade (** plesiomorphic- a primitive state, not unique to clade):
1: a) 1st ntennae biramous, a) raptorial mouth appendages, b) segment #6= maxilliped, c) many similar trunk segments (no trunk tagmata) with paddle-like biramous legs, d) pre-antennal process, e) eyes lost
2: a) 3 tagmata (head, thorax, abdomen), b) reduced number of body segments
3: a) abdominal appendages lost, b) abdomen of 11 segments, c) segment #5= leg-like, d) compound eyes lost
4: a) fully developed carapace, b) abdomen has fewer than 9 segments
5: a) maxillae (segments #4 & #5) reduced or absent (trunk segment number & limbs vary greatly)
6: a) thorax has fewer than 11 segments, b) abdomen has fewer than 8 segments
7: a) thorax has fewer than 7 segments , b) abdomen has fewer than 5 segments, c) unique naupliar eyes & loss of lateral compound eyes
Mal (Malacostraca): a) thorax of 8 segments with similar limbs, b) abdomen of 7 segments + telson, c) carapace covers head & thorax**, d) 1st antennae biramous, e) stalked eyes, f) gills on thoracic limbs
8: a) 2nd antennae uniramous, b) abdomen of 7 segments + telson **, c) 2nd maxilla like thoracic limbs, d) similar, phyllopodous thoracic limbs**
9: a) abdomen of 6 segments + telson, b) thoracic limbs stenopodous, c) long muscular abdomen, d) telson lacks rami
10: a) carapace covers head & 4 thoracic segments, b) limbs of first 5 thoracic segments uniramous, subchelate, c) thorax segment #2 with large subchela, d) moveable rostrum, e) gills on pleopods
Eumal (Eumalacostraca): a) carapace covers head & thorax (primitively)**
11: a) carapace not fused with all head & thorax segments**, b) thoracic oostegites form brood chamber, c) pre-juvenile manca stage
12: a) carapace fused dorsally with all head & thorax segments, 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)