Supplementary Information Characters used in phylogenetic analysis 316 of 337 characters listed below are extracted from Edgecombe (2004). That work provides literature citations for each character, together with cross-references to discussions of the characters in previous publications. New characters (characters 45-49, 65-67, 82, 89-92) are added or refined (69-70, 81, 88, 336-337) from more recent publications, for which citations are given below.
Euthycarcinoidea is coded as a single terminal taxon, with most information derived from the best preserved taxa, Heterocrania rhyniensis and Euthycarcinus kessleri. Interpretations of euthycarcinoid morphology that underpin codings are discussed below. Characters that are scored in Euthycarcinoidea are highlighted in bold. Mulistate
characters with ordered transformation series are indicated by ORDERED.
Dorsal closure of embryo: (0) definitive dorsal closure (dorsal covering of embryo participates in the definitive dorsal closure); (1) provisional dorsal closure (embryonic dorsal covering degenerates without participating in the definitive closure, which is exclusively derived from the embryo).
Ectoteloblasts forming part of metanaupliar/egg-naupliar region of germ band: (0) absent; (1) present, at anterior border of blastopore.
Origin of fat body: (0) fat body cells develop from vitellophages in yolk; (1) fat body cells develop from walls of mesodermal somites.
Midgut developed within the yolk: (0) midgut cells enclose the yolk; (1) lumen of embryonic midgut lacking yolk globules.
Fate map ordering of embryonic tissues: (0) presumptive mesoderm posterior to presumptive midgut; (1) presumptive mesoderm anterior to midgut; (2) mesoderm midventral, cells sink and proliferate, midgut internalises during cleavage; (3) mesoderm diffuse through the ectoderm; (4) midgut develops from anterior and posterior rudiments at each end of midventral mesoderm band.
Embryological development: (0) with a growth zone giving rise to both the prosoma and opisthosoma; (1) with a growth zone giving rise to the opisthosoma.
Engrailed expressed in mesoderm patterning: (0) present; (1) absent.
Epimorphic development: (0) absent; (1) present.
Nauplius larva or egg-nauplius: (0) absent; (1) present.
Pupoid stage (motionless stage after hatching, pupoid remains encased in embryonic cuticle): (0) absent; (1) present.
Sclerotisation of cuticle into hard, articulated tergal exoskeleton: (0) absent; (1) present.
Cuticle calcification: (0) absent; (1) present.
Cilia: (0) present in several organ systems (including nephridia, genital tract, and photoreceptors); (1) present in (at most) sperm.
Tendon cells with tonofilaments penetrating epidermis: (0) absent; (1) present.
Dorsal longitudinal ecdysial suture with forking on head: (0) absent; (1) present.
Transverse and antennocellar sutures on head shield: (0) absent; (1) present.
Resilin protein: (0) absent; (1) present.
Moulting gland: (0) absent; (1) present.
Bismuth staining of Golgi complex beads: (0) not staining; (1) staining.
Metanephridia with sacculus with podocytes: (0) absent; (1) present.
Distribution of segmental glands: (0) on many segments; (1) on at most last four cephalic segments and first two post-cephalic segments; (2) on at most second antennal and/or maxillary segments. ORDERED
Maxillary nephridia: (0) absent in postembryonic stadia; (1) paired; (2) fused nephridia of both maxillary segments.
Coxal gland orifice, leg I: (0) absent; (1) present.
Tömösváry organ (protocerebral “temporal organs” at side of head behind insertion of antenna): (0) absent; (1) present.
Malpighian tubules formed as endodermal extensions of the midgut: (0) absent, (1) present.
Malpighian tubules formed as ectodermal extensions of the hindgut: (0) absent; (1) single pair of Malpighian tubules at juncture of midgut and hindgut; (2) multiple pairs of tubules at anterior end of hindgut.
Form of ectodermal Malpighian tubules: (0) elongate; (1) papillate.
Neck organ: (0) absent; (1) present.
Hemoglobin: (0) absent; (1) present.
Subcutaneous hemal channels in body wall: (0) absent; (1) present.
Dorsal heart with segmental ostia and pericardial sinus: (0) absent; (1) present .
Interval valves formed by lips of ostiae projecting deeply into the heart lumen to prevent haemolymph backflow within the heart: (0) absent; (1) present.
Circumesophageal circulatory vessel ring with ventral, trumpet-shaped opening towards head: (0) absent; (1) present.
Slit sensilla: (0) absent; (1) present.
Ganglion formation: (0) ganglia formed from an invagination of the ventral organ; (1) neuroblasts.
Early differentiating neurons aCC, pCC, RP2, U/CQ, EL and AUN: (0) absent; (1) present.
EC neurons: (0) ECa and EPa only; (1) ECa, ECp and ECI.
Anterior pair of serotonergic neurons with neurites that cross to contralateral side: (0) absent; (1) present (Harzsch, 2004).
Posterior pair of serotonergic neurons with neurites that cross to contralateral side: (0) absent; (1) present (Harzsch, 2004).
Innervation of mouth area by anterior stomogastric nervous system: (0) absent; (1) present.
Ganglia of pre-oesophageal brain: (0) protocerebrum; (1) protocerebrum and deutocerebrum; (2) proto-, deuto- and tritocerebra.
Ganglia of post-oral appendages fused into single nerve mass: (0) absent; (1) present.
Fan-shaped body with neurons extending laterally into protocerebral lobes: (0) absent; (1) present.
Midline neuropil 1: (0) absent; (1) present.
Midline neuropil 2: (0) absent; (1) present.
Arcuate body in brain: (0) absent; (1) present.
Ellipsoid body in brain: (0) absent; (1) present.
Noduli in brain: (0) absent; (1) present.
Protocerebral bridge, composed of small bushy dendrites that intersect axons between the two halves of the brain; dendrites supply complex pattern of axonal projections to the fan-shaped body: (0) absent; (1) present.
Mushroom body calyces: (0) absent; (1) present.
Deutocerebral olfactory lobes with glomeruli: (0) absent; (1) present (Fanenbruck et al., 2004).
Deutocerebral olfactory-globular tract: (0) absent; (1) uncrossed; (2) with chiasma (Fanenbruck et al., 2004).
Deutocerebrum with bipartite antennular neuropils: (0) absent; (1) present (Fanenbruck et al., 2004).
Cephalon composed of one pair of preoral appendages and (at least) three pairs of postoral appendages: (0) absent; (1) present. The euthycarcinoid head has a single preoral appendage pair, the antenna (see character 117), with the mandible being the next appendage (character 133). Post-mandibular cephalic appendages have not been demonstrated (see character 159); we interpret the “buccal complex” best known in Euthycarcinuskessleri (Gall & Grauvogel, 1964, pl. 2) as the hypopharynx.
Cephalic tagma with four post-pedipalpal locomotory limbs (0) fewer limbs; (1) present (Vilpoux & Walossek, 2003). The tagmosis of euthycarcinoids does not correspond to that of chelicerates.
Prosoma with shield: (0) absent; (1) present.
Transverse furrows on prosomal carapace corresponding to margins of segmental tergites: (0) absent; (1) present.
Cephalic kinesis (movable ophthalmic / antennular segments and articulated rostrum): (0) absent; (1) present. The division of the head shield of euthycarcinoids into two cephalic tergites has been compared to Anostraca, in which the mandibular or cervical groove separates the sensory (first and second antennal) and gnathal regions of the head (Wilson & Almond, 2001: 154). In Mystacocarida, a strong groove on the dorsal side of the head shield separates the antennular and post-antennular segments (Olesen, 2001, fig. 4A). The difference in position of the grooves in branchiopods and mystacocarids cautions against forcing a homology with euthycarcinoids. The probability of homology between euthycarcinoids and anostracans is strained by the latter lacking a head shield or carapace. The present character is coded for a more elaborate style of cephalic kinesis in Malacostraca (Leptostraca and Stomatopoda), in which a rostrum, and antennular and ophthalmic sclerites have articulations with specific shared details of their musculation (Siewing, 1963).
Flattened head capsule, with head bent posterior to the clypeus, accommodating antennae at anterior margin of head: (0) absent; (1) present.
Lateral eyes: (0) absent; (1) simple lens with cup-shaped retina; (2) stemmata; (3) facetted; (4) onychophoran eye. The ‘sphaeroidal processes’ of euthycarcinoids (Schram & Rolfe, 1982) are most likely eyes, based on their size, shape, style of preservation, and position at the lateral margin of the head. Facets have not been observed in any euthycarcinoid but the shape of the ‘sphaeroidal processes’ is more similar to compound/faceted eyes (state 3) than to simple eyes. This inference is used for coding characters 75-79.
Compound eye stalked, basally articulated: (0) absent (eye sessile); (1) present. The ‘sphaeroidal processes’ of euthycarcinoids have no evidence for eye stalks. They are sufficiently well preserved in several species (e.g., Euthycarcinus kessleri) to regard this absence as real rather than a preservational defect.
Clear zone between dioptric apparatus and retina: (0) absent (apposition eye); (1) present (superposition eye).
Optic chiasma between lamina and medulla: (0) absent (uncrossed axons); (1) present.
Medulla divided into two layers by Cuccatini bundle: (0) undivided; (1) divided (Sinakevitch et al., 2003).
Lobula or protolobula receiving crossed axons from medulla: (0) absent; (1) present (Sinakevitch et al., 2003).
Third optic neuropil (lobula) separated from protocerebrum: (0) protolobula contiguous with protocerebrum; (1) lobula separated from protocerebrum (Sinakevitch et al., 2003).
Fourth optic neuropil (lobula plate), receiving uncrossed axons from medulla: (0) absent; (1) present (Sinakevitch et al., 2003).
Lateral eye rhabdomes with quadratic network: (0) absent; (1) present.
Number of median eyes: (0) none; (1) four; (2) three; (3) two; (4) one (embryonic).
Inverted median eye: (0) absent; (1) present.
Median eyes fused to naupliar eyes: (0) absent; (1) present.
Type of sensory cells in naupliar eye: (0) inverse; (1) everse.
Tapetal cells in cups of naupliar eye: (0) absent; (1) present.
Dorsal frontal organs: (0) absent; (1) present.
Ocular tubercle: (0) absent; (1) present.
Trichobothria innervated by several sensory cells, with dendrites having only indirect contact with the hair base: (0) absent; (1) present.
Basal bulb in trichobothria: (0) absent; (1) present.
Head/mouth orientation: (0) head prognathous, mouth directed anteroventrally; (1) head hypognathous, mouth directed ventrally; (2) mouth directed posteriorly. An anterior or ventral direction for the mouth has been argued based on the anterior extent of the sternites in Synaustrus (Edgecombe & Morgan, 1999) but without less equivocal data, as might be provided by sediment fill of the gut, this character is left unscored.
Labrum: (0) absent; (1) present. Coding accepts the interpretation of Wilson & Almond (2001, fig. 3B, for Smithixerxes pustulosus) that a triangular structure at the posterior edge of the cephalic doublure is a labrum.
Fleshy labrum with setulate sides and specialised glands: (0) absent; (1) present.
Entognathy (overgrowth of mandibles and maxillae by cranial folds): (0) absent; (1) present.
Admentum differentiated latero-ventrally on each side of head capsule, developed from posterior part of mouth fold: (0) absent; (1) present.
Sclerotic sternum formed by antennal to maxillulary sternites: (0) absent; (1) present.
Tritosternum: (0) absent; (1) present.
Hypopharynx: (0) absent or only a median lingua; (1) complete hypopharynx consisting of lingua and paired superlinguae.
Fulturae: (0) absent or limited to a hypopharyngeal suspensorium; (1) present, in groove between arthrodial membrane of maxilla and labium, connecting hypopharynx with posterior tentorial apodemes.
Posterior process of tentorium fused anteriorly with hypopharyngeal bar and transverse bar: (0) absent; (1) present. Given the strong preservation of trunk apodemes in several species of euthycarcinoids, the lack of tentorial apodemes in well-preserved material (especially Euthycarcinus kessleri) is scored as an absence rather than as a preservational ambiguity.
Post-cephalic filter feeding apparatus with sternitic food groove: (0) absent; (1) present. The wide, simple sternites of euthycarcinoids, coupled with the absence of strong setae on the coxae (Anderson & Trewin, 2003, pl. 1, fig. 3 for Heterocrania), indicate that branchiopod-style filter feeding was not practiced.
Appendage of second (deutocerebral) head segment: (0) locomotory leg 1; (1) antenna; (2) chelicera/chelifore; (3) jaw. The antenna of euthycarcinoids is coded as homologous with the first antenna (antennule) of Crustacea or the antenna of myriapods and hexapods. The fact that some crustaceans (notably branchiopods and terrestrial isopods) reduce the first antenna, such that the second antenna might be the first head appendage observed in a fossil (Wilson & Almond, 2001: 154) is acknowledged. However, the form of the euthycarcinoid antenna is typical of a sensorial, uniramous (first) antenna, as in myriapods and hexapods, rather than resembling the second antenna of branchiopods, and the antenna attaches near the anteroventral margin of the head shield (Schram and Rolfe, 1982).
Appendage on third (tritocerebral) head segment: (0) unspecialized locomotory leg; (1) second antenna; (2) intercalary appendage absent; (3) pedipalp; (4) oral papilla with slime glands and adhesive glands. Following the interpretation of the antenna of euthycarcinoids in character 117, an appendage is lacking between the antenna and mandible.
Single segmented antennal scale: (0) absent; (1) present.
Antennal naupliar protopod: (0) short; (1) long.
Distal-less expressed in mandible or positionally homologous appendage: (0) present (including transient expression in embryo and in palp); (1) absent in all ontogenetic stages.
Mandible (gnathobasic appendage of third limb-bearing metamere is main feeding limb of adult head, embedded beneath labrum, lacking Distal-less expression at inner margin): (0) absent; (1) present. Details of the euthycarcinoid mandibles (such as gene expression) are of course unknown. In spite of this, the appendage interpreted as a mandible in Apankura, Heterocrania, and Euthycarcinus is morphologically similar to a mandible, notably in the strong sclerotisation of its gnathal edge, and is clearly the main mouthpart of the adult head.
Mandible form: (0) antenniform, biramous, with protopod, endopod, and seven-segmented exopod; (1) with mandibular body and gnathal lobe.
Mandibular base plate forming side of head: (0) absent; (1) present. The mandibles of euthycarcinoids have no stipes or base plate, and the flattened head shield makes it unlikely that the mandibular would contribute to the side of the head capsule as is the case for diplopods and symphylans.
Independently musculated gnathal lobe, flexor arising dorsally on the cranium: (0) absent; (1) present.
Pectinate lamellae on mandible: (0) absent; (1) present.
Mandibular ‘shovel’ with terminal teeth: (0) absent; (1) present.
Second (anterior) mandibular articulation with the cranium, movement limited to transverse adduction around a horizontal axis of swing: (0) absent; (1) present.
Ball-and-socket mandibular articulation: (0) absent; (1) present, formed between clypeal condyle and mandibular ridges.
Mandibular scutes: (0) absent; (1) present (mandible composed of 2-5 movable scutes formed by subdivision of gnathal lobe).
Four sclerites of mandible intersecting at cruciform suture: (0) absent; (1) present.
Mandibular palp: (0) present (appendage of third limb-bearing cephalic metamere with telopodite); (1) absent throughout ontogeny; (2) present in larva, absent in adult. Euthycarcinoid mandibles lack a palp in adults, but the state in larvae is unknown; an “either state 1 or 2” coding is used.
Hand-shaped ‘movable appendage' between pars incisivus and pars molaris on mandible: (0) absent; (1) present.
Posterior tentorial apodemes: (0) absent; (1) present as metatentorium. See character 112 for the absence of tentorial apodemes in euthycarcinoids that preserve the trunk apodemes.
Pre- and metatentorium fused: (0) absent; (1) present.
Posterior suspension of anterior apodemes to cranial wall: (0) absent; (1) present.
Anterior tentorium: (0) absent (separate rod-like anterior tentorial apodemes); (1) anterior part of tentorial apodemes forms arched, hollow plates that approach each other mesially but remain separate; (2) anterior tentorium an unpaired roof. ORDERED
Salivary glands: (0) arise as ectodermal invaginations on second maxilla/labium; (1) arise as mesodermal segmental organs of first maxillae.
Opening of maxillulary salivary glands: (0) pair of openings at base of second maxillae; (1) median opening in midventral groove of labium; (2) median opening in salivarium, between labium and hypopharynx.
Maxillae on fourth limb-bearing metamere: (0) absent; (1) present. A complex setose structure medially in the post-mandibular part of the head of Euthycarcinuskessleri was described by Gall & Grauvogel (1964) as a buccal complex, according to them possibly including a hypophraryx and maxillae. No convincing evidence for an appendage was given, and their reconstruction of this region lacks any limbs. Their “buccal complex” is more similar to a setose hypopharynx than to a maxilla. Wilson & Almond (2001, fig. 3B) interpreted a structure in Smithixerxes pustulosus as a possible first maxilla, but it is a featureless wedge that cannot be identified as an appendage with a reasonable degree of confidence (it lacks articulations, setae or endites). Given the superb preservation of Euthycarcinuskessleri and the complex structure of the “buccal complex” we intepret euthycarcinoids as having a densely setose hypopharynx in the medial post-mandibular region, and lacking differentiated maxillae.
First maxillary precoxal segment: (0) absent; (1) present.
Number of medially-directed lobate endites on basal podomere of first maxilla: (0) two endites; (1) one endite.
First maxillary palps: (0) present (telopodite present on appendage of fourth metamere); (1) absent.
First maxilla divided into cardo, stipes, lacinia, and galea, with similar musculation and function: (0) absent; (1) present.
Interlocking of galea and superligua: (0) absent; (1) present.
First maxilla coalesced with sternal intermaxillary plate: (0) absent; (1) present, with unfused stipital and intermaxillary components; (2) mental elements of gnathochilarium consolidated. ORDERED
Second maxillae on fifth metamere: (0) appendage developed as trunk limb; (1) well developed maxilla differentiated as mouthpart; (2) vestigial appendage; (3) appendage lacking. Whether the third post-tritocerebral segment of euthycarcinoids is incorporated into the head is not known; following from discussion under character 159, if this segment is part of the head it appears to lack an appendage. Because the segmental limits of the head are uncertain, second maxillary characters are not scored.
Egg tooth on second maxilla: (0) absent (no embryonic egg tooth on cuticle of fifth limb-bearing metamere); (1) present.
Maxillary plate [basal parts of appendage of fifth limb-bearing metamere (second maxilla or labium) medially merged, bordering side of mouth cavity]: (0) absent; (1) present.
Coxae of second maxilla medially fused: (0) absent (coxae of appendage of fifth metamere not fused); (1) present.
Comb-like fringe of simple bristles on tarsus of telopodite of second maxilla: (0) absent; (1) present.
Symphylan-type labium (anterior plate with a row of papilla-bearing lobes distally and tapering proximal arms that extend back to a pair of cervical sclerites): (0) absent; (1) present.
Linea ventralis: (0) absent; (1) present.
Divided glossae and paraglossae: (0) undivided pair of glossae and paraglossae; (1) glossae and paraglossae bilobed.
Rotation of labial Anlagen: (0) absent; (1) present.
Widened apical segment of labial palp: (0) absent; (1) present.
Collum covering posterior part of head capsule and part of segment II: (0) absent; (1) present.
Direct articulation between first and fourth articles of telopodite of maxilliped: (0) absent; (1) present.
Coxosternite of maxilliped sclerotised in midline: (0) coxae separated medially, with sternite present in adult; (1) coxosternal plates meeting medially, with flexible hinge; (2) coxosternal plates meeting medially, hinge sclerotised and non-functional. ORDERED
Maxilliped coxosternite deeply embedded into cuticle above second trunk segment: (0) not embedded; (1) embedded.
Maxilliped segment with pleurite forming a girdle around coxosternite: (0) small lateral pleurite; (1) large girdling pleurite.
Tergite of maxillipede segment fused with tergite of first pedigerous segment: (0) separate tergites; (1) single tergite.
Sternal muscles truncated in maxilliped segment, not extending into head: (0) sternal muscles extended into head; (1) sternal muscles truncated.
Atrium between the inferomediana connecting the cardiac primary filter grooves with the pyloric filter grooves: (0) absent; (1) present.
Gut caeca: (0) absent; (1) present along midgut; (2) restricted to anterior part of midgut. Several species of euthycarcinoids preserve the gut, and none have caeca, which are as well preserved as the rest of the gut when the latter is preserved in other fossil arthropods (e.g., trilobites and trilobitomorphs).
Proctodeal dilation: (0) posterior section of hindgut simple, lacking a dilation; (1) proctodeum having a rectal ampulla with differentiated papillae.
Pyloric region with ring of flattened cells with thick intima: (0) absent; (1) present.
Peritrophic membrane: (0) absent; (1) present.
Radiating, tubular diverticula with intracellular final phase of digestion: (0) absent; (1) present.
Fusion of all (opisthosomal) tergites behind opercular tergite into a thoracetron: (0) absent; (1) present. Euthycarcinoids have free post-abdominal segments.
Opisthosoma greatly reduced, forming a slender tube emerging from between the posteriormost legs, with terminal anus: (0) absent; (1) present.
Lamellate respiratory organs derived from posterior wall of opisthosomal limb buds: (0) absent; (1) present.
Position of lamellate respiratory organs: (0) on opisthosomal segments 3-7; (1) on opisthosomal segments 4-7; (2) on opisthosomal segments 2-3.
Type of lamellate respiratory organs: (0) book gills; (1) book lungs.
Appendage on first opisthosomal segment: (0) appendage present on first opisthosomal segment in post-embryonic stages; (1) appendage absent.
Limb VII as chilaria: (0) absent; (1) present.
First opisthosomal segment: (0) broad; (1) narrow, developed as pedicel.
Claspers as a modified anterior thoracopod (coding restricted to taxa with phyllopodous limbs): (0) absent; (1) present.
Abdomen (limb-free somites between the terminal segment and limb-bearing trunk segments, posterior to expression domain of Ubx, abdA and abdB): (0) absent; (1) present. Although the postabdomen of Euthycarcinoidea is limbless, its Hox gene expression domains are unknown.
Pereion tagmosis: (0) one locomotory tagma; (1) two locomotory tagmata.
Thorax with three limb-bearing segments: (0) absent; (1) present.
Meso- and metathorax in mature stages bearing wings: (0) absent; (1) present.
Wing flexion: (0) absent; (1) present.
Segmentation of pleon: (0) seven segments; (1) six segments (including sixth pleomere fused with telson).
Diplosegments: (0) absent; (1) present. Decoupling of the sternites and tergites in euthycarcinoids is unlike the precise diplosegmentation of millipedes.
Dorsal endosternal suspensor of fourth postoral segment with anterolateral carapacal insertion: (0) absent; (1) present.
Tergal scutes extend laterally into paratergal folds: (0) absent; (1) present. Transverse sections through Heterocrania rhyniensis show the paraterga (Anderson & Trewin, 2003, text-fig. 8).
Paramedian sutures: (0) absent; (1) present.
Intercalary sclerites: (0) absent; (1) developed as small rings; (2) developed as pretergite and presternite. ORDERED
Trunk heterotergy: (0) absent; (1) present (alternating long and short tergites, with reversal of lengths between seventh and eighth pedigerous segments).
Trunk sternites: (0) each segment with large sternum; (1) sternal area divided into two hemisternites by linea ventralis; (2) sternal area mostly membranous, with pair of small sternites; (3) sternal plate (at least that of thoracic segments II and III) bears a Y-shaped ridge/apodeme; (4) sternites extended rearwards to form substernal laminae; (5) thoracic sternal areas reduced and partly invaginated along median line; (6) sternites lacking. Large, simple sternites (state 0) are shared by all euthycarcinoids.
Trunk endoskeleton in each segment: (0) pair of lateral connective plates; (1) pair of sternocoxal rods (ventral apodemes); (2) complex connective endosternite; (3) endoskeleton mainly cuticular, composed of two intrasegmental furcal arms and an intersegmental spinal process. The preabdominal apodemes of euthycarcinoids are scored the same as in Symphyla (Edgecombe & Morgan, 1999).
Pleural part of trunk segments: (0) pleurites absent; (1) supracoxal arches (catapleural and anapleural arches) on each segment; (2) pleural part of thoracic segments II and III consisting of single sclerite with large pleural process; (3) pleuron in each thoracic segment consists of single sclerite divided into anterior and posterior parts by pleural suture, from which pleural apophysis is invaginated, internal end connected to furcal arm. Transverse sections of Heterocraniarhyniensis showing the leg attachments (Anderson & Trewin, 2003, text-fig. 8) indicate that pleurites are absent.
Procoxal and metacoxal pleurites surround coxa: (0) pleurites absent or incompletely surrounding coxa; (1) procoxa and metacoxa surround coxa. Heterocrania rhyniensis demonstrates the absence of pleurites encircling the coxa (Anderson & Trewin, 2003).
Elongate coxopleurites on anal legs: (0) absent; (1) present.
Pleuron filled with small pleurites: (0) absent; (1) present.
Longitudinal muscles attach to intersegmental tendons: (0) absent; (1) present.
Lobopods with pads and claws: (0) absent; (1) present.
Articulated limbs with intrinsic muscles: (0) absent; (1) present.
Fundamentally biramous post-antennal limbs (endopod and exopod): (0) absent; (1) present. Euthycarcinoid preabdominal appendages are uniformly uniramous in the best preserved species (Euthycarcinus kessleri; Heterocrania rhyniensis; Schramixerxes gerem). A proposed antenniform exopod on some appendages of Euthycarcinus ibbenburensis (Schultka, 1991) is of uncertain identity.
Coxopodite(s) with gnathobasic endite lobes medially: (0) absent; (1) present. As in myriapods and hexapods, the presence of endites on the mandible is coded. Preabdominal limbs lack coxal endites (Anderson & Trewin, 2003, text-figs. 8, 9, pl. 1, fig. 3). Heterocrania rhyniensis provides the most reliable data for protopodal/coxal characters 239-243.
Paddle-like epipods: (0) absent; (1) present.
Trunk limbs with lobate endites formed by folds in limb bud, with indistinct proximal-distal axis of polarity: (0) absent; (1) present.
Coxal swing: (0) coxa mobile, promotor-remotor swing between coxa and body; (1) coxa with limited mobility or immobile, promotor-remotor swing between coxa and trochanter. The enlarged basal segment of the preabdominal legs of Heterocraniarhyniensis is coded as the coxa.
Coxopodite articulation: (0) arthrodial membrane; (1) pleural condyle; (2) sternal condyle; (3) sternal and pleural condyles; (4) internal plate. A pigmented knob at the inner margin of the coxa in Heterocrania rhyniensis (Anderson & Trewin, 2003, text-fig. 8A) is interpreted as a condyle. Its position is most consistent with a sternal articulation as in myriapods, being similarly positioned to the condyle at the proximal junction of the coxa and sternite in Lithobius (Manton, 1965: fig. 58).
Coxal vesicles: (0) absent; (1) present at limb base on numerous trunk segments; (2) on distal part of first abdominal appendage. Coding follows Edgecombe & Morgan (1999) in interpreting the sternal pores of euthycarcinoids as possible coxal vesicles.
Styli: (0) absent; (1) present.
Furcula: (0) absent; (1) present.
Musculi laterales: (0) absent; (1) present.
Coxotrochanteral joint: (0) simple; (1) complex. The identity of a trochanter in euthycarcinoids is uncertain, though if the enlarged basal segment (Anderson & Trewin, 2003, text-fig. 8) is the coxa, then state 0 is probably applicable.
Trochanteronotal muscle: (0) absent; (1) present.
Trochanter distal joint: (0) mobile; (1) short, ring-like trochanter lacking mobility at joint with prefemur.
Origin of posterior transpatellar muscle: (0) arises on distodorsal surface of femur, traverses femoropatellar joint ventral to axis of rotation, receives fibres from wall of patella; (1) arises on distal process of femur, traverses femoropatellar joint dorsal to axis of rotation, does not receive fibres from patella.
Tibiotarsus: (0) separate tibia and tarsus; (1) unjointed tibiotarsus.
Tarsus segmentation: (0) not subsegmented; (1) subsegmented.
Tarsal organ: (0) absent; (1) present.
Origin of pretarsal depressor muscle: (0) pretarsal depressor originates on tarsus; (1) pretarsal depressor originates on patella.
Pretarsal levator muscle: (0) present; (1) absent (depressor is sole pretarsal muscle).
Pretarsal claws: (0) paired; (1) unpaired.
Pretarsal claw(s) articulation: (0) on pretarsal base; (1) on distal tarsomere.
Plantulae: (0) absent; (1) present.
Tracheae/spiracles: (0) absent; (1) pleural spiracles; (2) spiracles at bases of walking legs, opening into tracheal pouches; (3) single pair of spiracles on head; (4) dorsal spiracle opening to tracheal lungs; (5) open-ended tracheae with spiracle on second opisthosomal segment; (6) many spiracles scattered on body. The absence of spiracles in euthycarcinoids is coded as a lack of tracheae.
Longitudinal and transverse connections between segmental tracheal branches: (0) tracheae not connected; (1) tracheae connected.
Pericardial tracheal system with chiasmata: (0) dendritic tracheae; (1) long, regular, pipe-like tracheae with specialised moulting rings.
Abdominal spiracles: (0) present (pleural spiracles on posterior part of trunk); (1) absent on first abdominal segment; (2) absent on all abdominal segments.
Abdominal segment XI modified as cerci: (0) absent; (1) present.
Articulate furcal rami: (0), absent; (1) present.
Uropods: (0) absent; (1) present.
Styliform post-anal telson: (0) absent; (1) present. The telson of euthycarcinoids is styliform, at least superficially like that of xiphosurans and scorpions. However, the anus of euthycarcinoids opens on the ventral side of the telson (Schram & Rolfe, 1982, pl. 3, figs. 1, 2), as in stem-group crustaceans such as Martinssonia (Müller and Walossek, 1986), rather than opening in front of the telson as in chelicerates
Anal segment with a pair of large sense calicles, each with a long sensory seta: (0) absent; (1) present.
Egg cluster guarded until hatching, female coiling around egg cluster: (0) absent; (1) females coils ventrally around cluster; (2) female coils dorsally around cluster.
Peripatoid and foetoid stages protected by mother: (0) absent; (1) present.
Female gonopod used to manipulate single eggs: (0) absent; (1) present.
Female abdomen with ovipositor formed by gonapophyses of segments VIII and IX: (0) absent; (1) present. No structure like an ovipositor is present in euthycarcinoids.
Gonangulum sclerite fully developed as ovipositor base, articulating with tergum IX and attached to 1st valvula/valvifer: (0) absent; (1) present.
Ovipositor opening at anteroventral part of opisthosoma: (0) absent; (1) present.
Legs on seventh trunk segment transformed into gonopods: (0) absent; (1) present. The legs of all preabdominal segments in euthycarcinoids are serially similar, without any differentiated in a gonopod-like manner.
Dignathan-type penes: (0) absent; (1) present. Following from the previous character, penes are not present in euthycarcinoids.
Penis (spermatopositor) opening on anteroventral part of opisthosoma: (0) absent; (1) present.
Male parameres: (0) undifferentiated; (1) pair of ‘lateral plates’ on segment XI; (2) pair of parameres on segment IX (second pair variably present on segment VIII); (3) incorporated into phallic apparatus as sclerites.
Penis on abdominal segment IX: (0) absent; (1) present.
Male gonopore location: (0) posterior end (opisthogoneate); (1) somite 11 (sixth pereion segment); (2) somite 12 (seventh pereion segment); (3) somite 8 (first opithosomal segment); (4) behind legs of somite 8 (second pair of trunk legs); (5) somite 13 (eighth pereion segment); (6) somite 17 (twelfth pereion segment); (7) somite 16; (8) on multiple leg bases; (9) between segments VIII and IX, more or less hidden by hind border of sternum VIII; (10) somite 19 (fourteenth trunk segment); (11) somite 9 (fourth pereion segment); (12) dorsal.
Female gonopore position: (0) on same somite as male; (1) two segments anterior to male; (2) six segments anterior to male; (3) seven segments anterior to male.
Striated core in subacrosomal space: (0) absent; (1) present.
Centrioles in sperm: (0) proximal and distal centrioles present, not coaxial; (1) coaxial centrioles; (2) single centriole; (3) centrioles absent in mature sperm; (4) doublet centrioles, each with a radial ‘foot’.
Centriole adjunct: (0) absent; (1) present.
Sperm ‘accessory bodies’ developed from the centriole: (0) absent; (1) present.
Cristate, non-crystalline mitochondrial derivatives in sperm: (0) absent; (1) present.
Connecting bands between axoneme and mitochondria: (0) absent; (1) present.
Axoneme parallels entire length of nucleus: (0) absent; (1) present.
Supernumary axonemal tubules (peripheral singlets): (0) absent; (1) formed from the manchette; (2) formed from axonemal doublets.
Number of protofilaments in wall of accessory tubules: (0) 13; (1) 16.
Nucleus of sperm forms spiral ridge: (0) absent; (1) present.
Nucleus of sperm with a manchette of microtubules: (0) absent; (1) present.
Coiling of spermatozoan flagellum: (0) absent (filiform sperm); (1) present.
Medial microtubules in spermatozoan axoneme: (0) two (9+2); (1) three (9 + 3); (2) none (9 + 0); (3) 12 + 0.
Sperm conjugation: (0) absent; (1) present.
Female spermathecae formed by paired lateral pockets in mouth cavity: (0) absent; (1) present.
Ovary shape: (0) sac- or tube-shaped, entire; (1) divided into ovarioles; (2) ovarian network.
Asymmetry of oviducts and ejaculatory ducts: (0) left and right ducts symmetrical; (1) left ducts rudimentary or absent.
Location of ovary germarium: (0) germarium forms elongate zone in the ventral or lateral ovarian wall; (1) germarium in the terminal part of each egg tube; (2) single, median mound-shaped germarium on the ovarian floor; (3) paired germ zones on ovarian wall.
Site for oocyte growth: (0) in ovarian lumen; (1) on outer surface of ovary, in hemocoel, connected by egg stalk.
Coxal organs on last pair of legs: (0) absent; (1) present.
Crural glands: (0) absent; (1) present.
Pair of repugnatorial glands in the carapace: (0) absent; (1) present.
Pleural defense glands with benzoquinones: (0) absent; (1) present.
labial expression domain: (0) expressed over multiple segments; (1) expression confined to second antennal/intercalary segment.
proboscipedia expression domain: (0) colinear with labial and Deformed domains; (1) anterior boundary of main expression domain of proboscipedia behind anterior boundary of Deformed.
Deformed expression domain: (0) expressed over three or more segments; (1) expression confined to mandibular and first maxillary segment.
Antennapedia expression domain: (0) strong throughout trunk; (1) restricted from the posterior of embryo.
Relative position of COI and COII: (0) COI/COII; (1) COI/tRNAL(UUR)/COII.
Relative position of tRNA-L: (0) lsu rRNA/L1/L2/NADH 1; (1) lsu rRNA/L1/NADH 1; (2) NADH 1/H'/lsu rRNA/L1; (3) lsu rRNA/L1/L2/Cytb (Lavrov et al., 2004).
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