Research on the mosquitoes of Angola - Systematic Catalog of ...

RIBIglRO, H. & RAMOS, H. Cunha -- <strong>Research</strong> on the mosquitoes o[ Angola X
Angola, the records of both forms are intermingled. Moreover, from
a few Angolan localities both forms (male terminalia examined) were
recorded at the same time. This simultaneous occurrence of both forms
(male records) had already been reported in Lobito (34), each form
occupying there its own breeding place. Though this is largely the rule
in Angola, in a few instances --such as at Cubal, Huambo and Moffimedes--
both pipiens s. str. and quinquefasciatus were seen breeding
in association in the same breeding place, as it was established by the
examination of the terrainalia of reared males.
Obviously, the preceding notes on the distribution of both forms
of the pipiens complex in Angola are in favour of the specific level of
distinctiveness and in accordance with the presumed specific rank of the
morphological differences.
The question now arises, however, as to the existence of naturally
occurring h-/bridization between the sympatric local populations of both
forms and its extent. It must be clearly stated here that no sure
indication that such hybridization occurs in nature could be found by
the writers in Angola. What we mean by can
perhaps be clarified as follows: (a) the terminalia of males of both
forms occurring simultaneously at the same localities or even reared
ex larva from the same breeding places could be easily attributed either
to pitiens s.s. or to quinquefasciatus; this decision was based on the
well known differences in the morphology of the phallosome (see above)
and, for the undistorded mounts, also on the determination of the
DV/D ratio (see above for ranges); (b) no (let us say,
with DV/D ratios between 0.2 and 0.8) were found, though a marked
variation was observed in the terminalia of quinquefasciatus from Mofamedes,
namely in that concerns the shape of the inner division,
the width of the sickle-shaped division and the appendages of the
coxite lobe. In fact, if hybridization occurred freely in the southern
half of Angola (where both forms are largely sympatric) and if hybrids
had the same rate of survival, it was expected that vast swarms
of hybrids would be found, rare being the places, if they existed, where
more or less pipiens and quinquefasciatus terminalia were not
linked by a continuous gradiant of . By the contrary,
from the available evidence it seems quite clear that, if hybridization
occurs in Angola, either it is a rare event or hybrids cannot establish
themselves in nature, or both. In other words, according to our data,
96 Estud., Efts. e Doc.- 134