Erythromachus Milne-Edwards 1874
Creators: name: Hume, Julian Pender
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Aves
Gruiformes
Rallidae
Erythromachus

description: Genus Erythromachus Milne-Edwards, 1874
Erythromachus Milne-Edwards 1874, p.6, pls.11–12. Type by monotypy: E. leguati Milne-Edwards
Etymology: From Greek eruthros = red, and makhç = battle, combat, in reference to the rail’s aggression shown towards red cloth.
Revised Diagnosis: Erythromachus differs from other Mascarene genera by the following characters:
Cranium (Fig. 6, 22): cranium medium-sized; in lateral view, dorso-ventrally compressed; small fonticuli orbitocraniales; large foramen n. optici; processus postorbitalis short and triangular; fossae temporales shallow.
Rostrum (Fig. 6, 22): os premaxillare long, os nasale narrow, and total length nearly 60% longer than cranium length; in lateral view, shallow; narial opening extremely long, extending for 66% the length of the rostrum; foramina neurovascularia present, not extending to rostral edge of narial opening; os nasale narrow; in ventral view, deep, wide sulcus.
Mandible (Fig. 6): rostrum mandibulae long and narrow terminating in a sharp point, length symphysis approximately 65% of cranium length; in dorsal view, processus mandibulae medialis indistinct; processus retroarticularis small; sulcus on crista intercotylaris deeply excavated; cotyla lateralis weakly U-shaped; os dentale long, narrow and terminating in a pointed tip; large foramina neurovascularia, deeply set and running almost to a deep sulcus situated in centre of mandible.
Scapula (Fig. 7): small and narrow; in lateral view, margo dorsalis distinct; facies articularis humeralis shallow; acromion blunt, rounded and directed dorsad; tuberculum coracoideum indistinct.
Coracoid (Fig. 8): short but shaft wide; in dorsal aspect, cotyla scapularis deep, oval-shaped; large foramen n. supracoracoidei sternal to processus procoracoideus; impressio m. sternocoracoidei deeply excavated.
Sternum (Fig. 9): small; processus craniolateralis narrow, directed laterad; in dorsal aspect; tuberculum labri externi indistinct; foramen pneumaticum on midline shallow; in ventral view; spina externa variable, reduced or more distinct and square-shaped; in lateral view, carina sterni extremely reduced; apex carinae directed ventrad.
Humerus (Fig. 10): extremely reduced, shaft curved dorsoventrally; in caudal aspect, incisura capitis deeply excavated; fossa pneumotricipitalis shallow; in cranial view, crista bicipitalis, short, square-shaped; fossa m. brachialis shallowly excavated.
Radius (Fig. 11): short; sulcus tendinosa deep extending proximad approximately ¼ of total length radius length; facies articularis radiocarpalis deflected ventrally; in ventral aspect, depressio ligamentosa deeply excavated.
Ulna (Fig. 12, 22): short and strongly arched dorso-ventrally proximally; tuberculum ligamentosa collateralis prominent; in caudal aspect, olecranon indistinct; processus cotylaris dorsalis short.
Carpometacarpus (Fig. 22): in dorsal aspect, processus extensorius short and rounded; os metacarpale majus robust; os metacarpale minus weakly arched creating narrow spatium intermetacarpale; proximal synostosis long.
Pelvis (Fig. 14, 22): in dorsal view, ala preacetabularis weakly expanded laterally; in lateral view, foramen ilioischiadicum is equal or slightly larger than foramen acetabuli; canalis iliosynsacralis extend to distal edge of foramen ilioischiadicum.
Femur (Fig. 15, 22): extremely robust; in cranial view, shaft curved medially and directed caudally at the proximal end; crista trochanteris strongly deflected mediad; in medial aspect, shaft strongly arched dorsally; in caudal aspect, condylus medialis larger than condylus lateralis.
Tibiotarsus (Fig. 15, 22): short, but robust; sulcus extensorius shallow and restricted proximally; canalis extensorius circular, less oval; pons supratendineus arched.
Fibula: short and robust; in dorsal view, caput fibulae narrow and weakly grooved caudally; tuberculum m. iliofibularis pronounced and excavated cranially.
Tarsometatarsus (Fig. 15): short, but extremely robust; in dorsal aspect, trochleae metatarsorum distinctly splayed, especially trochlea metatarsi II; metatarsi II directed slightly dorsad; presence of an ossified bridge connecting retinaculi extensorii individually variable; in plantar aspect, crista medialis hypotarsi central, not deflected laterally; in plantar aspect, surface area of foramen vasculare distale shallowly excavated; fossa metatarsi I extends proximad; hypotarsi deflected laterad; on proximal end, crista medialis flexoris digitorum longus present; sulci for tendon of musculus flexor perforatus digiti II and musculus flexor hallucis longus present.
Remarks: Milne-Edwards (1874), when describing Erythromachus, possessed both the original accounts and the first subfossil remains then recently discovered in caves on the Plaine Corail, Rodrigues (Fig. 4). These, along with elements of Rodrigues Night Heron Nycticorax megacephalus (Milne-Edwards, 1874), Rodrigues Turtle Dove Nesoenas rodericanus (Milne-Edwards, 1874) and Rodrigues Parrot Necropsittacus rodricanus (Milne-Edwards, 1867a), were sent to Milne-Edwards in Paris by Edward Newton, brother of Alfred Newton, professor at the UMZC (Milne-Edwards 1869b; A. Newton 1875b; Hume 2007, 2011a, 2014a, b) (data taken from labels). From these he determined that a flightless rail, related to Aphanapteryx on Mauritius, had once occurred on Rodrigues, and proposed a new genus, Erythromachus. As better material became available it was later referred to Aphanapteryx by Günther & Newton (1879); however, Piveteau (1945) noted that distinct differences in the cranium justified the generic separation of Erythromachus, which was an assignation followed by Olson (1977), Mourer-Chauviré et al. (1999) and others, and applied here. As recently shown in the endemic scops owls of Mauritius and Rodrigues (Louchart et al. 2018), there is precedent for differing evolutionary pathways for the two endemic genera of rails.
description: Published as part of Hume, Julian Pender, 2019, Systematics, morphology and ecology of rails (Aves: Rallidae) of the Mascarene Islands, with one new species, pp. 1-107 in Zootaxa 4626 (1) on pages 32-33, DOI: 10.11646/zootaxa.4626.1.1, http://zenodo.org/record/3335513