Neoschmidia, T. G. Hartley, 2003

Hartley, Thomas G., 2003, Neoschmidia, a new genus of Rutaceae from New Caledonia, Adansonia (3) 25 (1), pp. 7-12 : 8-9

Relationships of Neoschmidia

Neoschmidia appears to be most closely related to Halfordia F. Muell. , differing mainly in its axillary (vs. terminal) inflorescences, its 5-carpelled and - loculed (vs. 3 to 5-carpelled and -loculed), nearly apocarpous (vs. completely syncarpous or at apex septicidally fissured) ovary and fruit, its paired (vs. solitary) ovules, and its dry, follicular (vs. fleshy, drupaceous) fruit. As currently construed ( HARTLEY 2001b), Halfordia is monospecific and occurs in eastern Australia, New Guinea, New Britain, Vanuatu, and New Caledonia. ENGLER (1931), in the standard major work on Rutaceae , placed Halfordia in subfamily Toddalioideae tribe Toddalieae , but it now appears that all Malesian- Australasian plants he placed there are more correctly included in Rutoideae , and that within that subfamily Halfordia is best placed in tribe Zanthoxyleae (see HARTLEY 2001b).

It is worthwhile mentioning that Halfordia appears to have no other close relatives. The genus Skimmia Thunb. , which ranges from the Himalayas eastward to Japan and south to Vietnam and the Philippines ( TAYLOR 1987), closely resembles it superficially, but differs significantly in having haplostemonous (vs. diplostemonous) flowers, tetracolporate (vs. tricolporate) pollen ( HARTLEY 2001a), and a membranaceous testa which lacks sclerotesta (vs. testa thin and brittle, with sclerotesta).

Although Neoschmidia appears to be most closely related to Halfordia , it is most similar to Philotheca Rudge ( Rutoideae tribe Boronieae ), differing mainly in a single feature: its embryo has flattened, elliptic-oblong cotyledons that are about twice as wide as the hypocotyl, whereas that of Philotheca has ± plano-convex, linear cotyledons that are the same width as the hypocotyl. As currently construed ( BAYLY 1998; W I L S O N 1998a), Philotheca is endemic to Australia and consists of 46 species, 34 of which were previously assigned to Eriostemon Sm. (Boronieae) . Eriostemon itself, according to WILSON (1998a), who noted that the New Caledonian E. pallidus Schltr. is representative of a taxon quite distinct from both Eriostemon and Philotheca , consists of two species, E. australasius Pers. and E. banksii A. Cunn. ex Endl. , both endemic to Australia.

WILSON (1998a) noted that Eriostemon pallidus Schltr. (≡ Neoschmidia pallida ) differs from Philotheca in its very thick (vs. ± papery), induplicate-valvate (vs. imbricate) petals, its lack (vs. possession) of a sclerotesta and a circular chalazal aperture in the seed, and its elliptic (vs. linear, as “terete”) cotyledons. He also noted ( WILSON 1998a) that a sclerotesta and a circular chalazal aperture are found in the seeds of all Australian and New Zealand members of Boronieae , but have not been observed elsewhere.

My observations on Philotheca , the two species herein placed in Neoschmidia , and other relevant Rutaceae differ from WILSON’ s in the following cases. 1) The petals of Philotheca pungens (Lindl.) Paul G. Wilson appear to be about as thick as those of Neoschmidia . 2) The petals of Neoschmidia are narrowly imbricate or valvate in bud, and those of Philotheca pungens are valvate in bud. 3)The testa of Neoschmidia , viewed in transverse section, has an inner layer of dense, black sclerenchyma that I consider to be the sclerotesta, and examination of the inner surface of the testa reveals a circular chalazal aperture, located at the base of the seed. 4) Seeds of the New Caledonian Zieria chevalieri Virot , which clearly belongs in Boronieae , possess both a sclerotesta and a circular chalazal aperture, and in a study of the comparative morphology of 32 genera of Australasian- Malesian Rutaceae which I consider to belong neither to Boronieae nor subfamily Aurantioideae ( HARTLEY 2001b) , sclerotesta was recorded for the seeds of 23 genera, among which I have subsequently seen a circular chalazal aperture in at least some seeds of Acronychia J.R. Forst. & G. Forst. , Boronella Baill. , Brombya F. Muell. , Euodia J.R. Forst. & G. Forst. , Geijera Schott , Halfordia , Medicosma Hook. f., Melicope J.R. Forst. & G. Forst. , Myrtopsis Engl. , Sarcomelicope Engl. , and Zanthoxylum L.

As construed by HARTLEY (1995), Boronieae occur in Australia, New Caledonia, and New Zealand and comprise 17 genera, to which can now be added Leionema (F. Muell.) Paul G. Wilson ( WILSON 1998b), which was traditionally treated as a section of Phebalium . All of these genera have a linear embryo, which, as proposed by HARTLEY (1995), is a conservative feature that serves to define Boronieae as a natural group separate from all other Rutaceae of the Malesian- Australasian-Pacific region, in which the embryo is non-linear, having cotyledons that are considerably wider than the hypocotyl. (In that study I erroneously implied that the embryo of Eriostemon pallidus Schltr. is linear).

Thus, I assume that Neoschmidia would be misplaced in tribe Boronieae and propose its placement next to Halfordia in tribe Zanthoxyleae .