Meibomeus, Bridwell

Romero, Jesús & Johnson, Clarence Dan, 2002, Five New Species Of Meibomeus Bridwell From The New World With Host Records For Them And Six Named Species (Coleoptera: Bruchidae), The Coleopterists Bulletin 56 (2), pp. 182-202 : 199-201

Similarities of New Species and Named Species of Meibomeus

Of the new species described here, M. juarez is distinct from all other species of Meibomeus by having unique male genitalia ( Figs. 8, 9 ) and basal metasternal spines. Although the structure of the hind femur of M. jacki is very similar to M. apicicornis , the many distinct differences between M. jacki (see above) and other Meibomeus set it apart as a distinct species. The hind femora of M. dirli , M. rodneyi and M. campbelli are indistinguishable from each other. M. rodneyi , M. wenzeli , and M. campbelli , however, have apical metasternal spines. Meibomeus dirli lacks apical metasternal spines and differs in the structure of the male genitalia from all species of Meibomeus . The structure of the male genitalia separates M. rodneyi from these species and other Meibomeus . Meibomeus kirki is very similar in its structure to M. surrubresus but differs in the structure of the male genitalia from M. surrubresus and other Meibomeus . We did not attempt to establish species groups within Meibomeus because we agree with Kingsolver and Whitehead (1976) who stated ‘‘we do not recognize species groups because the species are similar, phylogenetic relationships are not sufficiently clarified, and no ecological or biogeographic units are evident.’’ We believe that there are ecological preferences shown by Meibomeus based on host preferences (see next section) that may be correlated with (perhaps causally) the phylogeny of species of Meibomeus and the phylogenetic differences between Meibomeus and other bruchid genera. The host data presented in this paper, however, were not available when Kingsolver and Whitehead studied Meibomeus .

Host Plants and Meibomeus

Many host records for Meibomeus were published in this paper ( Table 1 ). Kingsolver and Whitehead (1976), and Johnson (1979) published new host records for Meibomeus then Udayagiri and Wadhi (1989) summarized many of the hosts published up to 1989. All of these records were used to formulate Tables 2 and 3. All species of Meibomeus whose hosts are known feed in the seeds of the family Fabaceae , subfamily Papilionoideae . About 60% feed in species of Desmodium Desv. and slightly more prefer the tribe Desmodieae (Tables 2, 3). About 22% feed in seeds of the tribe Aeschynomeneae , a tribe more closely related to Desmodieae than to the other tribes that are hosts for Meibomeus . Meibomeus musculus feeds in seeds of five species of host plants, M. surrubresus feeds in four, and M. desmoportheus Kingsolver and Whitehead in three (Table 2). All the other species feed in either one or two hosts. We believe that it is likely that the host ranges of the species here are wider than reported because M. musculus , a species collected many times in the eastern United States, is more representative of most Meibomeus because the other species have not been as well sampled.

The trend of host range expansion of species groups of Meibomeus seems to have been into the tribe Desmodieae and less into other papilionoid Fabaceae , especially the Phaseolae and Robinieae . Further study of hosts of bruchids will determine if the tribes Indigofereae and Aeschynomeneae are frequent hosts for Meibomeus .

As with other taxa of bruchids and their hosts, our observations suggest a plethora of studies that could be conducted on species and populations of Meibomeus by systematists, ecologists, and other evolutionary biologists. For example, does selection on host preferences result in ecological speciation and drive the ecological diversification of this genus? Does the phylogenetic pattern of host use, whether causative or correlative, distinguish species within Meibomeus and between Meibomeus and closely related genera? Do species or populations that occur in marginal habitats use multiple hosts because of purely ecological pressures (e.g., M. musculus )?

Figures

Figs. 8–9. Meibomeus juarez male genitalia. 8) Median lobe; 9) lateral lobes.