Clumper

The clumper, MP, had no glucosyltransferase activity on the surface but did in the Golgi, while the non-clumper, HR, had it on the surface and not in the Golgi.

Source: wiktionary

[…] the same molecualr ^([sic]) weight as a clumper did not aggregate in broth (Fig. 4) .

Source: wiktionary

in the case of spreading versus clumping eggs, when the average fitness is calculated for a large number of spreaders, the issue of individual variance in reproductive success vanishes. Put another way, the contribution to the overall average fitness by a clumper who loses her nest and produces zero offspring is exactly offset by a successful clumper that produces a whole brood ( see also Hopper et al. 2003 )

Source: wiktionary

Bell compared the success of two species with contrasting architecture (a clumper and a runner form) as they grew either in competition with each other or alone.

Source: wiktionary