Lobostemon daltonii (Boraginaceae): a new species from the Western Cape, South Africa

Introduction LohoSlefl1()II Lehm., with about 30 species, is the largest genus in the southern A fri can Boraginaceae. This endemic genus is mainly confined to the winter-rainfall area of South A fri ca, occurring frolll Springbok to Mossel Bay, and further eastward along the coast to abou t Grahamstown, where the rain occurs throughout the year. Limited numbers of species exhibit a wide di stribution range with the norm, however, tending to be highly locali sed di stributions. Margaret Levyns last intensive ly studied Loboslemon in 1934. Extensive fieldwork was undertaken in the Bredasdorp-Cape Infanta area as part of a current systematic revi sion of the genus. During this time a Loboslemon species, not conforming to any known taxon , was brought to our attention by Nick O 'A lton. As a result, the new species Lobos!emoll dallonii M .H. Buys is described and named in recognition of Nick D 'A lton 's fri endl y ass istance during many visits to his farm .


Introduction
LohoSlefl1()II Lehm., with about 30 species, is th e largest genus in the south ern A fri can Boraginaceae. This endemic ge nu s is mainly confined to the winter-rainfall area of South A fri ca, occu rring frolll S prin g bok to Mossel Bay, and further eastward along the coast to abou t Grahamstown, where th e rain occ urs through out the year. Limited numbers of species exhibit a wide di stribution range with the norm , however, tending to be highly locali sed di stributions. Margaret Levyns last intensive ly studied Lob oslemon in 1934. Extensive fieldwork was undertaken in the Bredasdorp-Cape Infanta area as part of a current systematic revi sion of th e genus. During this time a Loboslemon species, no t co nforming to any known taxon , was brought to our attention by Nick O 'A lto n. As a resu lt, the new species Lobos!emoll dallonii M .H. Buys is described and named in recogniti o n of Nick D 'A lton 's fri en dl y ass istance during many visits to his farm .

Materials and Methods
A ll the materi al used in the study was collected during the peak fl owerin g season, i.e. between August and October. At least five leaves were studi ed anatomically. Transverse section s of wax-embedded laminae were cut with a rotary mi crotome and stained with a mi xture of Safranine 0 an Aleian green (Joel 1983). Sections were taken through the middle of the laminae.
The stigma and leaf indumentum were studied with a Joel scanning el ec tro n mi croscope (SEM), using secondary-electron detect ion and an acceleration voltage of 4-5 kY. The outer surfaces of the m eri carpids and sepal indumentulll were stud ied with a Philips XL30DX-4i SEM, using an accelerati on vo ltage of 10 kV. Fres h material for observation in the SEM was d ri ed using the CRYO method (Robards & Wilson 1993). Macromorpho logica l studies were do ne in the fi eld as well as from herbarium and conse rve d spec imens.

Leaf anatomy
Leaves isobilateral; amphistornatic, with the greatest number of stomata abaxially. Cuticle relatively thick, smooth. Epidermis cells relatively small, outer periclinal walls thickened; trichomes adaxially and abaxially, or glandular. Mesophyll differentiated into two layers palisade parenchyma adaxially and abaxially; hypodermis at the leaf margins and adaxial and abaxial to the midvein; collenchyrna adaxial and abaxial to the rnidvein; phenolic compounds scattered throughout the mesophyll. Vascular bundles enclosed in parenchymatous bundle sheaths.

Indumentum
The leaf indumentum is chiefly spinous, comprising either simple or pustular, appressed trichomes. These trichomes have a smooth texture (Figure 2). Scattered stalked glandular trichomes occur on both leaf surfaces. The indumentum of the herbaceous stems are similar to those of the leaves. Woody stems become glabrous with the development of cork.
The indumentum of the flowers, particularly the sepals, deserve special mention. The flower buds of L dalfollii seem preoccupied in deterring unwanted visitors in that a rich pro fusion of glandular as well as non-glandular trichomes occur on the sepal and petal surfaces ( Figure J). The glandular, multicellular trichomes ( Figure 4) are borne exclusively on the adaxially surface of the recurved sepal apices. The non-glandular trichomes are largely confined to the abaxial petal, and ab-and adaxial sepal surfaces.

Stigma and style
The stigmas produce no observable exudate and are, therefore, regarded as being dry. The receptive cells are concentrated in distinct zones or heads ( Figure 5). The stigma of L dallol1ii is bilobed, (or at best possesses high ly reduced stigma branches) in that only the stigmatic region is free with the rest of the two carpels being fused. The surface of the stigmas in L. daltonii is distinctly papillate, with the papillae being of a unicellular nature. These characters conform to those found in the majority of Loboslemoll species as well as to those found by Hes l o p~H arri· so n and Sh iv31l1l3 ( 1977) in EclriulI1 L. and most of the other Boraginaceous taxa.

Taxonomic note
The first collection made of L. da/follii is that of Levyns 83i2 (BOL) in 1947, identified to be L. Irigal/lls (Thunb.) H. Buek, a lso a member of the section Frulicosi. However. L dalfon;; dif· rers from the latter in that its leaves are distinctly coriaceous and the basal leaves especiall y are tran sversely incurved as opposed to th e he rbaceous leaves in genera l and the incurved basal leaves of /. Il"IgOlIllS in the vicinity of /. dal/onii. A form of L frigolllfs Ecology and distribution L. da/tonii fl owe rs ma in ly from October to November. It is restricted in its distri bution, being found excl usive ly near Cape Infan ta (Figu re 8), preferring the loamy soils in the tra nsition zone between Mountain Fy nbos (Rebelo 1996a) and South and South-west Coast Ren osterveld (Rebelo 1996b). Collections of L. dallonii have been few and far between, totalling four collectors with th e present revision. Th is could be indicative o f the relative remoteness of the locality . The precise number of individuals is currently unknown, although the impress ion obtai ned during field work is that there are a sufficient number present, not withstanding the overall restricted distribution range.
Additional field work is required to determine the precise co nservation status of the species.