Niphadomimus

Grebennikov, Vasily V., 2014, DNA barcode and phylogeography of six new high altitude wingless Niphadomimus (Coleoptera: Curculionidae: Molytinae) from Southwest China, Zootaxa 3838 (2), pp. 151-173 : 170-171

Biology of Niphadomimus weevils

No immature stages or a host plants are known for Niphadomimus and, therefore, all biological data is derived from what can be interpreted from the adult collecting circumstances. The genus, as presently known, consists of exclusively wingless and relatively high-altitude species, as least some of which are bisexual. All Niphadomimus specimens for which collecting information could be assessed (all, except Zherikhin’s two holotypes), have been collected by sifting forest litter in the Rhododendron -dominated forests or shrubs. None have been taken by opportunistically sampling under rocks in the alpine zone. The latter habitat is frequented by many other wingless high altitude weevils presumably for day time shelter. These latter species are normally not detected by sifting and are frequently found a relatively large distance away from the nearest woody vegetation, suggesting their independence from the latter resource. These considerations suggest that the species of Niphadomimus are not truly alpine species but rather inhabitants of the upper forest zone partly or fully dependant on wooded vegetation in their development and could not be expected to be found far from the food source.

Another biological peculiarity of Niphadomimus weevils is their remarkable rarity in sifted samples, coupled with occasional abundance. The great majority (70–90%) of samples taken in the seemingly appropriate Rhododendron -dominated habitats in the localities where Niphadomimus is known to occur failed to record the genus (total number of samples not shown). When detected, the genus would normally be represented by a single specimen of a single species discovered after a few days of intense sampling. Consider that 11 among 14 Niphadomimus collecting events pertained indeed to singletons (all four specimens from Nepal, plus seven Chinese records, including the 2010 record of N. electra sp. n.). Only two samples from the Cang Shan Mountain Range taken within two days of 4–5.vii.2011 resulted in long series of N. electra sp. n., and, most uncommonly, one of them additionally included all nine presently known specimens of N. maia sp. n. ( Fig. 15 ). It is extraordinary that both the exceptionally rich 2011 sites are located within one kilometre from each other, were equally diligently sampled a year earlier (18–19.v.2010) and provided only a singleton of N. electra sp. n., the first representative of the genus ever recorded in China. The latter results suggest strong and presently unexplainable temporal fluctuations of adult specimen density.

Figures

FIGURE 15. Habitat and the type locality of Niphadomimus electra sp. n. and N. maia sp. n. on the eastern slope of Cang Shan in south-eastern Yunnan, China, above the town of old Dali at 3,740m (noted on labels as sifting #37 taken on 5.vii.2011). This is the only locality where two Niphadomimus species have been seen together in the same sample. This is also the exact locality for N. maia sp. n. known from nine specimens from a single sample. Note the presence of conifers (in the background) in the predominantly broadleaved high altitude forest dominated by tall Rhododendron spp. overhanging the trail. The sifter with the half-full bag containing 39 live specimens of both Niphadomimus species, including both holotypes, is in the foreground. The darker sifted litter, appearing disturbed, is immediately to the left of the trail. This sample, together with another taken nearby on the previous day (siftings #35 and #36 in 2011) are by far the richest for Niphadomimus providing 89 of the 100 known specimens.