5. The finitimus valve pattern group

In the worker’s enteric valve, the primary cushions are of two types: the even PCs are similar to the PCs of the basic enteric valves but the odd PCs, in their downstream part, are wide and bear at that place a higher density of rather short bristles (Fig. 16A). The primary cushions, particularly the odd PCs, are roughly rectangular and rather wide, thus giving an impression of massiveness (in comparison with the other patterns): their lateral margins are almost parallel until the bristly part, where they are more or less narrowed (Fig. 11F). The bristly parts of the odd PCs are wider than they are high or globular (as high as they are wide) with a density of short bristles becoming abruptly high; as a consequence, on a microscope slide, these bulges are almost never twisted and can hardly be seen in profile (Fig. 11 F’). The enteric valve thus shows triradial symmetry.

An odd PC is made of (a) an upstream spiny part (12–30% of total length) with relatively strong spines, (b) a middle spiny part (39–62% of total length) with somewhat weaker spines and with 17–37 lateral supporting bristles on each side, and (c) a bristly part (22–34% of total length) with 75–125 straight and rather short bristles on a bulge as wide as or wider than high; behind this area, the bristly part bears 20–30 large, curved or hooked bristles (Fig. 16A).

The secondary cushions are wide at the upstream end, narrowing noticeably downstream with a homogeneous spine scattering (Fig. 16A).

In the soldier’s enteric valve, the PCs are also relatively wide, and the bristly parts, although weakly developed, are always present and recognisable by the density of bristles becoming abruptly higher (Fig. 16B). The secondary cushions are like those of workers but bear less developed spines.

This basic valve pattern is therefore characterised by low and wide crests which are densely hairy on the downstream end of the odd PCs; most species are large.

Material examined

Twelve known and one unknown species, and a variety have such enteric valves: