Szabó János szerk.: Fragmenta Mineralogica Et Palaentologica 23. 2005. (Budapest, 2005)

42 Dui The insertion plate of the head valve is cut by three slits, from which the two laterals are shallow, while the middle is slightly deeper. There is a third head valve with rather special characters (Plate V: 10-12): the outline is pearshaped, all of the slits are shallow and the surface of the valve seems to be smooth, without any ornamentation. However, this smoothness is due only to the lost of tegmentum (see comments in remarks). More than 40 specimens represent the intermediate and tail valves, which are very variable in appearance. Several specimens are large-sized (up to 6.5 mm long) and correspond with the materials known from the literature (intermediate valves: Plate VI: 1-4; tail valves: Plate VI: 5—11). These valves are elongated triangular in outline. The mucro is rounded (Plate VI: 2, 5) or pointed (Plate VI: 1, 6). The smooth jugal area is rectangular, with parallel sides (Plate VI: 5, 9) or slightly wedge-shaped (Plate VI: 2, 8). The jugal area shows several pores: the larger macroaesthetes are situated in longitudinal rows, while the microaesthetes arranged in bunches at the anterior side of the macroaesthetes (Plate VI: 10). Eroded specimens generally show larger and undifferentiated pores (Plate VI: 3—4). The lateral areas are ornamented by 6-8 longitudinal, sometimes slightly undulating ribs. The ribs may become granulöse near the mucro (Plate VI: 1, 9) . The pores arranged along the grooves between the ribs. The small microaesthetes are at the deeper part of the grooves, while the row of macroaesthetes can be observed along the lateral sides of the grooves (Plate VI: 7, 11). The suturai plates are elongated triangular in outline, with very variable length, changing between 39—70% of the total length (see most extremely long suturai plates at Plate VI: 1). Some specimens show strong growth lines (Plate VI: 1, 5-6, 9). Beside the large-sized valves, several small intermediate and tail valves were found in the Bánd material (Plate VII: 1-15; Plate VIII: 1-12). Some of these intermediate valves correspond well with the well-known larger ones; the only differences are the smaller size and the larger W/L ratio (0.37-0.43 at large intermediate valves, 0.63-0.68 at small ones). These specimens represent the III—VII valves of the animal (Plate VII: 1— 10) . However, the shape and appearance is significantly differ at II intermediate valve, where the width is very near to the length (W/L ratio is 0.74-0.81) and the jugal area is not rectangular or slightly wedge-shaped but definitely wedge-shaped with very wide anterior base (Plate VII: 11-15). W/L ratio of the jugal area is 0.380.48 at the II valves, while 0.3-0.33 at the other small valves (and 0.11-0.14 at large-sized ones). There are also four tail valves among the small-sized specimens, where the outline is oval and slighdy elongated (Plate VIII: 1—12). W/L ratio is 0.35-0.47 at large tail valves, 0.58-0.64 at small ones. The jugal area is slightly wedge-shaped. The ribs are strongly granulöse at the mucro. Not only the relatively high suturai plate run around below the tegmentum at the small-sized tail valves, but the granulöse ribs also go round the mucro because the jugal area do notrun until the posterior end of the valve (Plate VIII: 6,10). Remarks — The only other Cryptoplax species (C. margitae DULAI) from the Miocene of the Central Paratethys was described from Hungary by DULAI (2001). Another species is known from the Mediterranean region; C lanceolatus LAGHI was recognized from Montegibbio on the basis of a head valve and a tail valve by LAGHI (1977). Recently DELL'ANGELO et al. (2005) shortly described a new Cryptoplax species from Läpugiu (Cryptoplax viàani DELL'ANGELO et al., 2005) on the basis of intermediate valves. According to the authors, it differs from C. weinlandi in morphological characters (W/L= 0.64-0.78), in the number of longitudinal ribs (up to 10) and in the lateral view of the valves. However, according to DELL'ANGELO (2005, pers. comm.) and KROH (2005, pers. comm.), who was reviewer of DELL'ANGELO et al.'s paper, it is synonym of C. weinlandi, and these shorter intermediate valves represent the II valve of this species, which is much shorter than the other intermediate valves. This opinion is accepted here and the variability of the valves is shown on the basis of the rich Hungarian material. SCHWABE (2005, pers. comm.) called my attention to the similarity between my small-sized, short intermediate valves and the corresponding valves of Choneplax indica ODHNER, 1919 (e. g. see SCHWABE 2004; DELL'ANGELO et al. 2004). However, Choneplax would be a rather exotic element in the Central Paratethyan fauna, and at the same time Cryptoplax may have such intermediate Explanation to Plate V 1-4 Acanthochitona faluniensis (ROCHEBRUNE, 1883). 1 Intermediate valve — (L: 2.9 mm; W: 4.1 mm), Bánd, 18x. 2 Details of image 1 — eroded granules of the lateral area, 105x. 3 Intermediate valve — (L: 3.0 mm; W: 4.7 mm), Bánd, 16x. 4 Details of image 3 — eroded surface of posterior part of the jugal area, 65x. 5-12 Cryptoplax weinlandi SULC, 1934. 5 Head valve — (L: 2.75 mm; W: 2.3 mm), Bánd, 22x. 6 Details of image 5 — granulated ribs and the arrangement of macro- and microaesthetes, 72x. 7 Head valve — (L: 1.8 mm; W: 1.3 mm), Bánd, 30x. 8 Details of image 7 — granulated ribs of the tegmentum, 130x. 9 Details of image 8 — granules and the arrangement of macro- and microaesthetes, 380x. 10 Head valve without tegmentum — (L: 3.1 mm; W: 2.8 mm), Bánd, 19x. 11 Details of image 10 — erosional scratches at the left side of the articulamentum, 210x. 12 Details of image 10 — shallow middle slit of the insertion plate, 40x.