Traveller SPRING 2022

Science
In 2017, some of this work led to her
doctorate from Rhodes University about
a genus of South African snails called
Chondrocyclus. These live in forests and
thicket. She described twelve new species
that no one had noticed before in the
process. There’s good reason for that: the
biggest Chondrocyclus species is the size
of a Panado, but most are smaller. And their
dark brown shells are often caked with soil,
making them doubly difficult to spot.
The equally tiny Gulellas are slightly
easier to find, because their white shells
tend to stand out against dark soil. Over the
years, Mary has described 16 such species
– the most recent being eight in a paper
published earlier this year with Dai.
Among those she named is
Chondrocyclus kevincolei. It was named as
such in a 2019 paper in the scientific journal
European Journal of Taxonomy, and it’s
Mary’s way of thanking her husband, Kevin,
for his indispensable assistance on fieldtrips.
Mary recently completed an index of all
558 species and 12 subspecies of land snail
found in South Africa. Her efforts were part
of the South African National Biodiversity
Institute’s (SANBI) collation of a thorough
checklist of the country’s animals, including
vertebrates and invertebrates.
Members of the Sheldonia
genus of land snails are
commonly called tailwagger
snails.
How to find a snail
Mary fully realises that there are generally
three camps when it comes to snails: you
either love them, you hate them, or you
know almost nothing about them. Mary, of
course, falls into the first camp.
She is therefore quick to point out that
among the world’s 30 000 land snail
species, only about a hundred are of the
common garden variety that have become
agricultural pests.
“Very few have any sort of interaction
with people. Most are very small and live
their whole lives in forests or concealed
among leaf litter, without us even knowing
they’re there.”
To go snail hunting, you need a careful
eye, a torch, even some magnifying lenses,
a fair share of luck, and a willingness to
get muddy hands and knees. Forests,
especially those along South Africa’s
eastern coastline, tend to be the obvious
spots to look for land snails. Some hide
among decomposing leaves or under logs
or rocks, while others are easier to find as
they scrape algae off tree trunks.
“Remember to look up when you are in a
forest. Some species live in trees. You may
see their silhouettes as they sit on leaves.”
“Snails are generally only active after rain,
in damp conditions,” she notes.
“Most local species are found in the
eastern half of the country, the wetter areas.
For snails it’s a big challenge to live on
land, so it’s actually amazing that so many
species have adapted to do so.”
It might therefore come as a surprise that
some species live in the aloes in the Karoo
or that a whole family of land snails, the
Dorcasiidae, is endemic to the dry western
parts of southern Africa.
“The Dorcasiidae contain 13 species in
South Africa, and are found in the Western
Cape, Northern Cape and Eastern Cape and
extend into Namibia and Botswana.” Among
them are some of the earliest South African
land snails ever described, including
Trigonephrus rosaceus, which was already
identified in 1774 by Danish naturalist Otto
Friedrich Müller, and Trigonephrus
namaquensis from Namaqualand, named
as such in 1891.
Images: Mary Cole, Kevin Cole and Dai Herbert
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Marjorie’s snail
The first example of Gulella latimerae was collected in 2000,
in the Kumqolo Forest near Xhora. According to a paper Mary
and Dai wrote in African Invertebrates in 2004 about it and three
of their other snail discoveries, it is only known to occur in four
forest patches along the Eastern Cape Wild Coast, between
Mazeppa Bay and Ntafufu.
“Many of the species we have discovered are only found in very
small areas. It reflects the very patchy nature of forests, and how
species have evolved over millennia in isolation because they
cannot easily disperse to new areas,” explains Mary.
“From a conservation point of view, it is therefore always
important to conserve our indigenous forests and the habitats
of our indigenous species, because most are only found in
small areas.”
AA Traveller | SPRING 2022