Ardeinae, Leach, 1820

Scofield, R. Paul, Worthy, Trevor H. & Tennyson, Alan J. D., 2010, A Heron (Aves: Ardeidae) from the Early Miocene St Bathans Fauna of Southern New Zealand, Records of the Australian Museum 62 (1), pp. 89-104 : 95-96

Subfamily Ardeinae

(Day Herons, Egrets, Night Herons)

Support for the inclusion of Matuku in Ardeidae is provided by a single unambiguous apomorphy: the absence of a plantar metatarsal groove (sulcus flexorius) and coincident presence of metatarsal facet. The tarsometatarsi of night herons (tribe Nycticoracini ) differ from those of other members of the Ardeidae , by the following combination of characters ( Steadman et al., 2000):

1 The trochlea metatarsi IV is slightly grooved distally, rather than deeply grooved or ungrooved.

2 The distal foramen (foramen vasculare distale) is small and placed more proximally than the proximal end of trochlea metatarsi III.

3 The trochlea metatarsi III is deflected laterally from the axis of the shaft (corpus tarsometatarsi) in night herons (this character is shared only with bitterns).

4 The trochlea metatarsi II has slight deflection from the shaft (corpus tarsometatarsi) so extends only slightly mesad of the shaft, not markedly.

5 The crista plantaris medialis is prominent proximally.

6 There is a lack of obvious dorsal metatarsal (sulcus extensorius) and plantar metatarsal grooves (sulcus flexorius) with the crista plantaris lateralis being indistinct.

Matuku otagoense differs from members of Nycticoracini in all these features and most noticeably in the lack of lateral deflection of trochlea metatarsi III and in having a large distal foramen. Additionally, members of this tribe have the medial margin of the shaft immediately distal to the cotyla medialis dorso-plantarly compressed forming a prominent thin crest, which Matuku otagoense lacks.

Tarsometatarsi of day herons and egrets (Tribes Ardeini and Egrettini respectively) have obvious dorsal metatarsal and plantar metatarsal grooves, with a distinct abbreviation description mm

tarsometatarsus (holotype S.50003) A maximum distal width 12.9 B maximum distal depth 7.9 C width of trochlea metatarsi III 3.8

preserved length 92.6 D estimated total length ca. 98

right coracoid (S.50004) E maximum cranial width (from humeral facet to brachial tuberosity) 8.0 F maximum shaft width (below procoracoid) 5.4 G length of humeral facet 8.3 H depth of humeral facet 5.7

left quadrate (S.50852)

I depth from capital squamosum to cond. lateralis 16.9 J depth from capital squamosum to cond. medialis 16.9

left quadrate (S.50854)

I depth from capital squamosum to cond. lateralis 16.8 J depth from capital squamosum to cond. medialis 16.9

axis (S.50853)

K width of facies artic. cranialis 4.1 L inter condyle distance 13.6 M width single zygapophysis caudalis 3.6 N depth single zygapophysis caudalis 3.6 O greatest width (estimated across zygapophyses caudalis) 10.3

lateral intermuscular line (crista plantaris lateralis). The tarsometatarsi of Egretta and most Ardea are much longer with comparatively narrower shafts than Matuku otagoense , but those of Butoroides and Ardea ibis are shorter and more gracile than the fossil. We conclude therefore, that the St Bathans fossil is not an ardein heron.

Subfamily Cochleariinae (Boat-billed Herons) The tarsometatarsus of Cochlearius (Cochlearinae) is very similar to that of Nycticorax but differs in the following characters: in Cochlearius the dorsal metatarsal groove is slightly deeper and usually more well defined; the intercotylar prominence usually projects less proximally; the trochlea metatarsi III is less elevated relative to the trochlea metatarsi IV; the trochlea metatarsi II is less wide. None of these features are found in Matuku otagoense .