74 



J. WATSON, S.J. LYDON & N.A. HARRISON 



Stomata densely packed within groove, longitudinally or obliquely 

 orientated, surrounded by sparsely scattered isodiametric ordinary 

 epidermal cells up to 20 |am across. Stomatal apparatus comprising 

 guard cells each about 35 pm long and 8 |im wide, with square-ended 

 polar appendages, surrounded by a ring of about 10 subsidiary cells, 

 each bearing a long, hollow papilla overhanging a slit-like stoma. 

 Subsidiary cells of adjacent stomata often in contact but never 

 shared. 



Name. After Detritus, troll and member of the Ankh-Morpork 

 City Watch in the Discworld novels of Terry Pratchett. 



HOLOTYPE AND LOCALITY. V.64608, Fig. 35E, a dispersed leaf 

 fragment from the plant debris beds near Hanover Point, on the 

 South West coast of the Isle of Wight. Wessex Formation; Barremian. 



Material and occurrence. All specimens of Toneyites dethti 

 sp. nov. figured here have been found as well-preserved dispersed 

 leaves within the 'plant debris beds' of the Wessex Formation. Figs 

 35 A-F I-0: 36A-N; 37A-G; 38A-C; 39; 40 show material from the 

 South West coast of the Isle of Wight; Fig. 35G, H shows material 

 from Swanage, Dorset. T. detriti was also identified by Oldham 

 (1976) in samples from Dorset at Worbarrow and Swanage, the 

 South West coast of the Isle of Wight, and also from the Ashdown 

 Beds at Hastings in Sussex. Stratigraphical range: Berriasian - 

 Barremian. 



Description and discussion. The leaf specimens of Torreyites 

 detriti sp. nov. recognised so far are elliptical (Figs 35A; 36A, D, E, 

 J, L) or needle-shaped (Figs 35B, C; 36B. C, H, I). Although most 

 leaves can readily be identified either as needles or as wider elliptical 

 forms, apparently intermediate forms can also be recognised (Fig. 

 36F, G). There is no distinct petiole and in some leaves the extreme 

 base appears to be a round leaf-scar (Fig. 35D) which almost 

 certainly indicates abscission. The basal region is commonly twisted 

 (Figs 35D, F; 36J-N), a feature which has recently been discussed in 

 some detail by Watson & Harrison (1998) in relation to the leaves of 

 Pseitdotorellia linkii using \W\ng Abies for comparison. If, as is quite 

 likely, the leaves of T. detriti were borne in two distinct ranks then 

 some degree of twisting would be related to leaf insertion in the 

 living shoot. Conifer shoots of this type present the thickly cutinized 

 adaxial surface of all the leaves uppermost but this is a secondary 

 dorsiventrality superimposed on spiral leaf insertion. In order to 

 achieve this, some leaves are twisted at the base more than others 

 (Watson & HaiTison 1998, fig. ID). Such twisting can also be 

 simulated in the laboratory by leaving pieces of shoot or isolated 

 leaves exposed for a few days. The twisting of leaf bases in Torreya 

 nucifera becomes much more exaggerated when left to dry. We 

 cannot rule out the possibility, of course, that the twisting is related 

 to post-mortem drying and shrinkage in T. detriti. 



The leaf tip is frequently absent (Fig. 35E), perhaps indicating a 

 scarious nature in life. Where present, the apex is mucionate (Fig. 

 35G, H). The frequent absence of the extreme tip in conifer leaves of 

 this type is very common, has repeatedly been discussed in the 



literature and is mentioned here under the description of 

 Sciadopityoides above. 



The two longitudinal stomatal grooves on the lower surface of the 

 leaf of T. detriti (Figs 35A-I; 36A-N) are usually filled with sedi- 

 ment and show as pale bands on the shiny black leaves. Thus they 

 stand out as a very distinctive feature which makes the leaves of this 

 species easy to spot and pick out of bulk debris material. After 

 cleaning in hydrofluoric acid the stomatal grooves appear brown and 

 dull and still stand out clearly (Fig. 35A, C) against the shiny, black, 

 non-stomatal regions. Quite small cuticle scraps with just a portion 

 of the distinctive groove are for this reason also easy to recognise. 



The upper surface of the leaf is less remarkable (Fig. 35 J) with the 

 upper cuticle (Fig. 35J-0) showing the inegular shape of the ordi- 

 nary epidermal cells of the marginal areas contrasting with the 

 four-sided elongate cells arranged in longitudinal files over the 

 midrib (Fig. 35K, L). The outer surface of the upper cuticle bears 

 rather distinctive longitudinal ridges (Fig. 35M, N) and the light 

 microscope shows that there are generally two of these ridges per 

 longitudinal file of cells (Fig. 350). 



The lower cuticle (Figs 37A-G; 38A-C; 39; 40) shows the longi- 

 tudinal files of four-sided ordinary epidermal cells outside the 

 grooves; those in the median regions more elongate than those of the 

 marginal regions (Fig. 37 A, B). The outer surface often bears the 

 same longitudinal ridges seen on the upper cuticle being more 

 pronounced in the few files of cells nearest to the groove (Figs 37C; 

 38A, B). These cell files also bear short, round papillae, usually with 

 depressed tips (Fig. 38A, B) and longer, hair-like papillae which 

 overhang the groove individually, or fuse laterally to form long 

 cutinized fringes (Figs 37C, D; 38A, B). 



There is a high density of longitudinally or obliquely orientated 

 stomata scattered within the grooves (Figs 37A; 39; 40), but there are 

 also many long papillae on the subsidiary cells and the groove 

 margins obscuring the details of the stomata, particularly an outside 

 view in the SEM (Figs 37C; 38A. E). In the light microscope they are 

 also difficult to discern (Fig. 37E) but see Fig. 41 and comments 

 below. The inner surface of the groove in the SEM shows the 

 stomatal apparatus to consist of a pair of guard cells with square- 

 ended polar appendages (Fig. 37F, G), and slit-like openings (Figs 

 39; 40), suiToundedby aringof up to 10 or so subsidiary cells (Fig. 

 37F, G). Subsidiary cells of adjacent stomata are often in contact but 

 never shared (Figs 37A: 39). 



Oldham (1976) described two types of cuticle fragments, 12 

 Cycad BeC which he described as cycadalean and 3 1 Taxod ScA as 

 a Sciadopitys-Wkt leaf. However, additional material from Oldham's 

 and other localities has shown them to be identical to T. detriti. Fig 4 1 

 shows drawings of a leaf from the Lower Cretaceous of Poland made 

 by Watson during a visit by the late Dr Maria Rey manowna to the late 

 Professor T.M. Hanis in 1962. Reymanowna (pers comm. 1962) 

 intended to describe this leaf as Torreya or Torreyites but we have no 

 knowledge of her having done so. From the drawings it appears to us 

 to be identical to Torreyites detriti but the present whereabouts of the 

 leaf are unknown. However, it is likely that further specimens could 



Fig. 35 A-O Torreyites detriti sp. nov. All from Wessex Formation. A-I, L-O, from the South West coast of the Isle of Wight; J, K from Swanage, Dorset. 

 A, elliptical leaves, L-R: V.64595-V.64599, x 2.5; B, needle-shaped leaves, V.64600-V.64606, x 2.5; C, single long needle, V.64607, x 5; D, leaf 

 fragment showing round leaf-scar at base and basal twisting, V.64606. x 5; E, holotype, leaf dissected to show both upper and lower cuticle. V.64608. x 

 10; F, leaf fragment showing twisted base and longitudinal grooves, V.64609. LM. x 10; G, leaf fragment with mucronate apex. V.646I0. LM, x 25; H, 

 leaf tip mounted on stub lower surface uppermost, showing longitudinal grooves. V.6461 1. SEM. x 25; I, lower cuticle showing longitudinal grooves. 

 V.646I2. LM, X 25; J, upper cuticle showing cell elongation over midrib, V.6461 2. LM, x 25; K, upper cuticle showing more regular, elongate ordinary 

 epidermal cells in longitudinal rows over midrib towards right, and less regular cells of marginal regions to left, V.6461 2. LM. x 125; L, inside view of 

 upper cuticle showing more regular, elongate ordinary epidermal cells in longitudinal rows over midrib towards right, and less regular cells of marginal 

 regions to left, V.64613, SEM, x 1 25; M, outer surface of upper cuticle bearing regular longitudinal ridges, V.64614, SEM, x 125; N, longitudinal ridges 

 in detail, V.64614, SEM, x 500; O, light micrograph of upper cuticle focussed to show relationship between cells and ridges, V.64612, LM, x 500. 



