6. The oculatus valve pattern group

The workers within this pattern have basic enteric valves (Fig. 17A): all six primary cushions are similar in their arrangement but not in their sizes.

The primary cushions are roughly triangular: their largest width is generally located near their upstream end and their lateral margins converge gradually downstream until the bristly part, where they remain parallel (Fig. 11B). The enteric valve shows bilateral symmetry, PC1 being much longer and often wider than the other PCs (WVP1-Pre> 1.30) (Fig. 17A).

PC1 is made of (a) an upstream spiny part (40–66% of total length) with relatively strong spines, (b) a middle spiny part (10–27% of total length) with somewhat weaker spines and generally with 5–8 lateral supporting bristles on each side, and (c) a bristly part (22–38% of total length) with 30–50 straight, curved and eventually hooked bristles (Fig. 11B).

The secondary cushions, near their upstream end, are never wider than the primary cushions; however, in some cases, they widen in their downstream, bristly, fuzzy parts (Figs 4G, 17A). The secondary cushions SC12 and SC61 (on both sides of PC1) are often faint or may be totally lacking (Fig. 17A).

In the soldier’s enteric valve, the primary cushions are well outlined except at their upstream end; PC1 is much longer than the other primary cushions (SVP1-Pre> 1.25) and often substantially widened between the first upstream quarter and the middle (Fig. 17B). The secondary cushions are like those of workers but bear less developed spines.

This basic valve pattern is characterised by a long PC1 and therefore by high bilateral symmetry and PC1 pre-eminence indices in both soldiers and workers, and by the high elongation index of the workers’ SCs (Table 5); most species are small.

Material examined

Two species have such enteric valves: