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structurally. Haemaphysaline host-adapted structures are more pronounced in males
than in females, presumably because females are somewhat larger and possibly
stronger, and do not wander on the host in search of several mating partners as do
males. These adaptations are less pronounced in nymphs and larvae, presumably
because these tiny ticks can slip between the host hairs. Among different species
constituting SP subgenera, a stepwise progression is exhibited from species to spe-
cies, from larvae to nymphs to adults as well as males and females of individual
species. This progression provides a clear picture of structural evolution through
history. This progression can be seen when one is passing through different species
of SP, SI, and SA haemaphysaline ticks. Among the SP species, adults of
Mesozoic-type relics, chiefly parasitizes Artiodactyla, are seen mostly in
Himalayan and outlaying Palearctic and Oriental alpine and subalpine zones.
These tick species either lack pronounced coxal spurs (as did Mesozoic reptile
parasites) or have exceptionally large coxal spurs (hair-hooking devices). On the
capitulum, specialized hair-hooking devices developed only after the narrowly
elongate SP palpi changed to compact or posteriorly broadened structures. The pri-
meval SPs are the largest in the genus. The dominating trend toward size reduction
operates simultaneously with palpal broadening. Mammal-parasitizing haemaphysa-
lines have a variety of hair-hooking devices—spurs on the coxal and trochanter
spurs, basis capituli spurs (cornua), and palpal spurs and marginal indentations or
slits—to assist the small tick in reaching a feeding site or a mate on the hairy host.
These devices are especially luxuriant in smaller sized (physically weaker) species
and in males, which are smaller than females and are promiscuous mate-seekers,
moving about on the host more than females do. In bird-parasitizing haemaphysa-
lines, there is little or no development of these devices except (atypically) in minute-
sized species. Tenrecs-parasitizing species that feed among the spines and harsh
hairs of the body have luxuriant capitular, coxal, and trochanter spurs, but those spe-
cies that feed in the glabrous ears are virtually spurless (like bird-infesting species).
Ornithophysalis, with its broad palpi, appears to have evolved abruptly from SP
subgenera with compact palpi when birds and mammals replaced reptiles as the
world's dominant vertebrates. Significantly, of the 20 contemporary Ornithophysalis
species, six parasitize only birds, five parasitize both birds and various mammals,
three parasitize birds and marsupials or only marsupials, two parasitize only tenrecs,
and four parasitize Oriental or Australian rodents. The only haemaphysalines which
specifically parasitize the phylogenetically ancient tenrecs (Insectivora) are the SP
species H. (Sharifiella) theilerae and the three SA species constituting the subgenus
Elongiphysalis, which represents a highly specialized branch from Ornithophysalis.
Except for the few species of the subgenus Haemaphysalis that parasitize birds as
well as mammals, all other SA haemaphysaline adults are specific to mammals and
never feed on birds, although immatures of a few SA species may infest birds. The
four contemporary Ornithophysalis species specific to Oriental and Australian
rodents suggest an early association between these ticks and mammals in the
Oriental and Australian regions and, together with other evidence, with the origin of
the genus Haemaphysalis in the Oriental region. The Australian and Oriental
marsupial- and rodent-infesting species probably evolved from species like the
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