Balian E.V., L?v?que C., Segers H., Martens K. (Eds.) Freshwater Animal Diversity Assessment
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266 Hydrobiologia (2008) 595:257–266
123
FRESHWATER ANIMAL DIVERSITY ASSESSMENT
Global diversity of crabs (Aeglidae: Anomura: Decapoda)
in freshwater
Georgina Bond-Buckup
·
Carlos G. Jara
·
Marcos Pe
´
rez-Losada
·
Ludwig Buckup
·
Keith A. Crandall
© Springer Science+Business Media B.V. 2007
Abstract The freshwater anomuran crab s of the
family Aeglidae are all restricted to southern South
America occurring in Chile, Brazil, Bolivia, Uruguay,
Paraguay, and Argentina. The family consists of a
single genus, Aegla, containing 63 currently described
species. There are another 5–10 known yet unde-
scribed species to complement this diversity. The
aeglids occur in freshwater lakes, streams, rivers, and
in caves with freshwater. The origin of the family
appears to be from marine ancestors from the Pacific
invading streams in Chile about 75 mya radiating both
in Chile and again on the eastern side of the Andes,
particularly in Brazil. Of the 63 species, 23 or 36.5%
are considered under threat and are in need of
conservation action.
Keywords Conservation · Freshwater biology ·
Crab · Decapoda · Anomura · Aeglidae ·
Diversity · South America
Introduction
The Aeglidae are the most abundant and widely
distributed freshwater decapod “crabs” in southern
South Amer ica. Unlike true brachyuran crabs, how-
ever, in aeglids the fifth pair of pereiopods is reduced
in size, lacking walking capacity (Lopr etto, 1978;
Martin & Abe le, 1988); they also possess tiny chelae
with which they groom branchiae and eggs attached
to the pleopods of females and the underside of the
abdomen (Martin & Felgenahuer, 1986) (Fig. 1,
inset). All aeglids are primarily aquatic and occur in
lakes, streams, and caves, at depths of down to 320 m
in Chilean lakes (Jara, 1977), and at altitudes of up to
∼3,500 m in northeastern Argentinean cordilleras
(Bond-Buckup & Buckup, 1994). Aeg lids are the
only anomuran family restricted to the Neotropical
region of South America. Taxonomically, aeglids are
included within the anomuran superfamily Galatheoi-
dea, but there is some morphological evidence (e.g.,
gill structure and caparace sutures) and molecular
Guest editors: E. V. Balian, C. Le
´
ve
ˆ
que, H. Segers &
K. Martens
Freshwater Animal Diversity Assessment
G. Bond-Buckup · L. Buckup
Departamento de Zoologia, Universidade Federal Do Rio
Grande Do Sul, Porto Alegre, Brazil
G. Bond-Buckup
e-mail: gbond_buckup@yahoo.com.br
C. G. Jara
Instituto de Zoologı
´
a, Universidad Austral de Chile,
Casilla 567, Valdivia, Chile
M. Pe
´
rez-Losada · K. A. Crandall
Department of Biology, Brigham Young University,
Provo, Utah, 84602-5181, USA
K. A. Crandall (&)
Monte L. Bean Life Science Museum, Brigham Young
University, Provo, Utah, 84602-5181, USA
e-mail: keith_crandall@byu.edu
123
Hydrobiologia (2008) 595:267–273
DOI 10.1007/s10750-007-9022-4
data that suggest the Aeglidae should be in their own
superfamily (Martin & Abele, 1986; Pe
´
rez-Losada
etal., 2002b; Tudge & Scheltinga, 2002). From a
conservation perspective, several of the known spe-
cies are very restricted in distribution, and they and
their habitats are considered threatened (Pe
´
rez-Los-
ada etal., 2002a). From an ecological perspective,
aeglids are unique because they are the only anomu-
ran family entirely restricted to freshwater habitats.
The adult size of aeglids does not surpass 60 mm
carapace length (CL), and color varies according to
the substrate, from greenish brown to almost black; in
some lacustrine populations blue, yellow, orange, and
red specimens are also sporadically found (Jara,
1989). Aegla are dioecious; males lack pleopods, and
genital pores open on the coxa of fifth pair of
pereiopods at the tip of membranous tubes; female
genital pores open on the coxa of third pereopods
(Martin & Abele, 1988). Spawning occurs chiefly
during the autumn, but some species spawn
continuously throughout the year (Bahamonde &
Lo
´
pez, 1961; Rodrigues & Hebling, 1978; Bueno &
Bond-Buckup, 2000). The incubation period las ts
between four and eight months, so that an adult
female produces no more than one clutch of eggs per
annum. Fecundity depend s on the size of females,
ranging between 120 eggs at 12.5 mm CL to 400 at
22.5 mm CL female in A. laevis (Bahamonde &
Lo
´
pez, 1961); between 115 eggs at 14.99 mm CL to
368 at 19.18 mm CL female in A. leptodactyla
(Buckup personal observation); and between 699
eggs at 29 mm to 1043 at 33 mm CL female in
A. rostrata (Jara, 1977). Egg size ranges betwee n
1.00 and 1.37 mm diameter (Jara, 1977). Recruitment
normally occurs once a year, in springtime (August to
October) (Bahamonde & Lo
´
pez, 1961; Lo
´
pez 1965;
Bueno & Bond-Buckup, 2000), but for A. longirostri
and A. castro, it seems that two recruitment periods
exist (Swiech-Ayoub & Masunari, 2001; Delevati
etal., 2005). Aegla species lack larval stages;
Aegla spinosa
22°
30°
38°
22°
30°
38°
66
°
58°
50°
74°
66°
58°
50
°
42°
1
A-B
D
E
C
Andean Cordillera
Sierraas
Pampeanas
Massif
Cordillera de la Costa
Fig. 1 Map of southern South America indicating the major river systems and distribution of the major clades (cf. Fig. 2) of species
diversity in the aeglid crabs. A drawing of Aegla spinosa from Bond-Buckup and Buckup (1994) is shown as an inset
268 Hydrobiologia (2008) 595:267–273
123
Table 1 Species from the freshwater anomuran crab family Aeglidae including the countries within which they are distributed
Species Distribution Habitat
Aegla abtao Schmitt, 1942 Chile River
Aegla affinis Schmitt, 1942 Chile, Argentina River
Aegla alacalufi Jara & Lo
´
pez, 1981 Chile Small streams
Aegla araucaniensis Jara, 1980 Chile River
Aegla bahamondei Jara, 1982 Chile River
Aegla camargoi Buckup & Rossi, 1977 Brazil River
Aegla castro Schmitt, 1942 Brazil River
Aegla cavernicola Turkay, 1972 Brazil Cave
Aegla cholchol Jara & Palacios, 1999 Chile River
Aegla concepcionensis Schmitt, 1942 Chile Small streams
Aegla denticulata denticulate Nicolet, 1849 Chile River
Aegla denticulata lacustris Jara, 1989 Chile Lake
Aegla expansa Jara, 1992 Chile Small stream
Aegla franca Schmitt, 1942 Brazil River
Aegla franciscana Buckup & Rossi, 1977 Brazil River
Aegla grisella Bond-Buckup & Buckup, 1994 Brazil River
Aegla hueicollensis Jara & Palacios, 1999 Chile River
Aegla humahuaca Schmitt, 1942 Argentina Headwater & Lake
Aegla inconspicua Bond-Buckup & Buckup, 1994 Brazil River
Aegla inermis Bond-Buckup & Buckup, 1994 Brazil River
Aegla intercalata Bond-Buckup & Buckup, 1994 Argentina River
Aegla itacolomiensis Bond-Buckup & Buckup, 1994 Brazil River
Aegla jarai Bond-Buckup & Buckup, 1994 Brazil River
Aegla jujuyana Schmitt, 1942 Brazil River
Aegla laevis laevis Latreille, 1818 Chile River
Aegla laevis talcahuano Schmitt, 1942 Chile River
Aegla lata Bond-Buckup & Buckup, 1994 Brazil River
Aegla leptochela Bond-Buckup & Buckup, 1994 Brazil Cave
Aegla leptodactyla Buckup & Rossi, 1977 Brazil River
Aegla ligulata Bond-Buckup & Buckup, 1994 Brazil River
Aegla longirostri Bond-Buckup & Buckup, 1994 Brazil River
Aegla manni Jara, 1980 Chile Small streams
Aegla marginata Bond-Buckup & Buckup, 1994 Brazil River
Aegla microphthalma Bond-Buckup & Buckup, 1994 Brazil Cave
Aegla neuquensis Schmitt, 1942 Chile River
Aegla odebrechtii Mu
¨
ller, 1876 Brazil River
Aegla obstipa Bond-Buckup & Buckup, 1994 Brazil River
Aegla occidentalis Jara etal., 2003 Chile River & Lake
Aegla papudo Schmitt, 1942 Chile River
Aegla parana Schmitt, 1942 Brazil River
Aegla parva Bond-Buckup & Buckup, 1994 Brazil River
Aegla paulensis Schmitt, 1942 Brazil River
Aegla perobae Hebling & Rodrigues, 1977 Brazil Headwater Cave
Aegla pewenchae Jara, 1994 Chile River
Aegla plana Buckup & Rossi, 1977 Brazil River
Hydrobiologia (2008) 595:267–273 269
123
offspring hatch as juvenile “crabs” of 1.13 - 1.58 mm
CL (Bond-Buckup etal., 1999) that remain with the
mother for 3–4 days before living independently
(Lo
´
pez etal., 2004 ). Population density varies widely,
reaching up to 250 individuals/m
2
(Bahamonde &
Lo
´
pez, 1961) in highly productive conditions.
The ecological role of Aegla species has not been
assessed but their omnivorous diet includes periph-
yton, decaying allochtonous vegetable matter, aqua-
tic invertebrates (Bahamond e & Lo
´
pez, 1961; Burns,
1972; Lara & Moreno, 1995, Castro-So uza & Bond-
Buckup, 2004), and fine particulate organic matter
(Isler, 1988). Additionally, they constitute a relevant
dietary item for the non-native rainbow trout
(Oncorhynchus mykiss) in Chile and South Brazil
and brown trout (Salmo trutta fario) in Chile (Burns,
1972; Arenas, 1978; Buckup, personal observation),
and for the Chilean and Brazilian species of river
otter (Lontra provocax ) (Medina, 1998).
Species diversity
The present Aeglidae belong to a single genus, Aegla
Leach, 1820, consisting of 63 described species
(Bond-Buckup & Buckup, 1994; Bond-Buckup,
2003) (Table 1); including, newly described species
based on recent molecular phylogenetic analyses
(Jara etal., 2003). By our count, there are at least six
additional species waiting to be described. Of these
species, 57 are found mainly in riv ers, only two in
lakes, and four in cave habitats.
Phylogeny and historical processes
Ortmann (1902) proposed that aeglid species from Chile
represented the more primitive forms of the genus.
However, Schmitt (1942) hypothesized that Aegla from
the Atlantic side of South America were more primitive,
and species ranging in the Chilean streams were more
derived. Recent estimates of phylogenetic relationships
based on a variety of molecular data support the Pacific
origin hypothesis (Pe
´
rez-Losada etal., 2004) (Fig. 2) and
suggest that the group, as a whole originated around
75 mya. The western Aegla species radiated, approxi-
mately, 40–45 mya (clades A and B—Fig. 2), but the
speciation of the central and eastern taxa took place
later, around 23–35 mya (clades C-E in Fig. 2) (see
Pe
´
rez-Losada etal., 2004 for more detailed discussions
on the phylogenetic relationships among all the aeglid
species).
Table 1 continued
Species Distribution Habitat
Aegla platensis Schmitt, 1942 Brazil, Argentina, Paraguay, Uruguay River
Aegla prado Schmitt, 1942 Brazil, Uruguay Swamp & Lake
Aegla ringueleti Bond-Buckup & Buckup, 1994 Argentina River
Aegla riolimayana Schmitt, 1942 Chile, Argentina River
Aegla rossiana Bond-Buckup & Buckup, 1994 Brazil River
Aegla rostrata Jara, 1977 Chile Lake
Aegla sanlorenzo Schmitt, 1942 Argentina River
Aegla scamosa Ringuelet, 1948 Argentina River
Aegla schmitii Hobbs III, 1979 Brazil River
Aegla septentrionalis Bond-Buckup & Buckup, 1994 Argentina, Bolivia Headwater
Aegla serrana Buckup & Rossi, 1977 Brazil River & Headwater
Aegla singularis Ringuelet, 1948 Argentina, Brazil River
Aegla spectabilis Jara, 1986 Chile River
Aegla spinipalma Bond-Buckup & Buckup, 1994 Brazil River
Aegla spinosa Bond-Buckup & Buckup, 1994 Brazil River
Aegla strinatii Turkay, 1972 Brazil River
Aegla uruguayana Schmitt, 1942 Argentina, Uruguay, Brazil River
Aegla violacea Bond-Buckup & Buckup, 1994 Brazil River
270 Hydrobiologia (2008) 595:267–273
123
0.005 substitutions/site
A. papudo
A. ringueleti
A. scamosa
A. scamosa
A. bahamondei
A. occidentalis
A. neuquensis
A. affinis
A. alacalufi
A. manni
A. hueicollensis
A. denticulata lacustris
A. denticulata denticulata
A. riolimayana
A. abtao
A. abtao
A. abtao
A. spectabilis
A. araucaniensis
A. pewenchae
A. laevis talcahuano
A. laevis laevis
A. laevis talcahuano
A. cholchol
A. rostrata
A. cholchol
A. cholchol
A. spinipalma
A. marginata
A. camargoi
A. camargoi
A. camargoi
A. paulensis
A. perobae
A. parva
A. parana
A. castro
A. castro
A. parana
A. schmitti
A. cavernicola
A. strinatii
A. strinatti
Aegla n. sp. 2
A. leptodactyla
A. jarai
Aegla n. sp. 3
A. jarai
A. spinosa
A. jarai
A. jarai
A. jarai
A. odebrechtii
A. jarai
A. jarai
A. singularis
A. platensis
A. rossiana
A. uruguayana
A. platensis
A. platensis
A. platensis
A. intercalata
A. intercalata
A. prado
A. violacea
A. violacea
A. humahuaca
Aegla n. sp. 6
A. septentrionalis
A. jujuyana
A. sanlorenzo
Aegla n. sp. 1
Aegla n. sp. 5
A. marginata
A. leptochela
A. inconspicua
A. serrana
A. serrana
A. franciscana
A. franciscana
A. ligulata
A. obstipa
Aegla n. sp. 4
A. itacolomiensis
A. plana
A. grisella
A. grisella
A. inermis
A. longirostri
A. longirostri
A. affinis
Clade A
42.5 2.6 my
*
*
*
*
Clade B
41.0 1.5 my
Clade C
33.2 1.8 my
Clade D
25.1 0.9 my
Clade E
24.3 0.7 my
lnL: -40,497.16
(74.0 my)
(C=37.0 my)
Fig. 2 Bayesian and maximum likelihood estimate of
phylogenetic relationships among the aeglid species using
the GTR+Γ+I model of evolution. Clade support is
graphically indicated as follows:
–
bp ≥ 70% and
pP ≥ 0.95,
50% ≤ bp < 70% and/or 0.75 ≤ pP < 0.95,
and — bp < 50% and/or pP < 0.75. Branch lengths are
shown proportional to the amount of change along the
branches in the maximum likelihood tree with estimated
divergence dates shown for the root and major clades (see
Pe
´
rez-Losada etal., 2004, for details)
Hydrobiologia (2008) 595:267–273 271
123
Present distribution and areas of endemicity
The aeglids are distributed in southern South America
(Fig. 1) including Chile, Brazil, Argentina, Uruguay,
Bolivia, and Paraguay. Thus, all 63 species are
contained within the Neotropical region. There are 16
species endemic to Chile, seven species endemic to
Argentina and 36 species endemi c to southern Brazil
(Bond-Buckup etal. 2003). They occur in all the main
rivers of southern South America, except the most
southern Patagonian drainages.
Human related issues
Most Aegla species have very narrow distributional
areas and are therefore of significant conservation
concern. Of the 63 species currently recognized in the
genus, using the IUCN Red List criteria (IUCN,
2001), we recognize 23 species or 36.5 % as under
threat or endangered, mainly due to their narrow
distributions and the rapid degradation of the fresh-
water habitats they occupy.
In Chile, aeglids are recognized as an important
food item for exotic salmonid species (Salmo trutta
fario and Onc orhynchus mykiss) which support a fast-
growing fly-fishing sport industry, especially in the
Llanquihue Lake region and South Brazilian High-
lands. On the negative side, the fast-growing fruit and
wine producing industries in Central Chile constitute a
threat for conservation of aeglids, and benthic river
fauna in general, due to the widespread use of biocides,
which likely accumulate and have an impact in rivers
and streams. Threats for conservation of aeglids also
derive from silvicultural practices related to the
establishment of extensive plantations of pine and
Eucalyptus, mainly along the Coastal Cordillera and
south Brazil. Additionally, it must be pointed out that
the exaggerated use of pesticides in the widesp read
apple tree and potatoes cultivation and mainly, the hog
raising activities along the majority of the South
Brazilian Rivers, are an important menace to the native
populations of aeglids, particularly in the states of
Santa Catarina and Rio Grande do Sul, in Brazil.
Acknowledgements We thank Estelle Balian and Koen
Martens for their invitation to participate in this exciting
project and for their helpful comments on our paper. We also
thank Darren Yeo and an anonymous reviewer for their helpful
comments to improve the paper. Our work was supported by
the Conselho Nacional de Desenvolvimento Cientı
´
fico e
Tecnolo
´
gico (CNPq) (National Research Council, Brazil -
GBB) and NSF grants OISE-0530267 and EF-0531762.
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Hydrobiologia (2008) 595:267–273 273
123
FRESHWATER ANIMAL DIVERSITY ASSESSMENT
Global diversity of crabs (Crustacea: Decapoda: Brachyura)
in freshwater
Darren C. J. Yeo Æ Peter K. L. Ng Æ
Neil Cumberlidge Æ Ce
´
lio Magalha
˜
es Æ
Savel R. Daniels Æ Martha R. Campos
Springer Science+Business Media B.V. 2007
Abstract An assessment of the global freshwater
crab diversity is presented. A total of 1,476 species in
14 families are currently known from all zoogeo-
graphical regions (except Antarctica), including
1,306 species in eight exclusively freshwater families
(Pseudothelphusidae, Trichodactylidae, Potamonauti-
dae, Deckeniidae, Platythelphusidae, Potamidae,
Gecarcinucidae and Parathelphusidae). Estimates of
true freshwater crab dive rsity includi ng likely num-
bers of undescribed taxa suggest that the field remains
largely in a ‘‘discovery’’ phase. Main ideas on the
origins, diversification, and phylogeny of true fresh-
water crabs are briefly discussed. The economic
importance of freshwater crabs is also highlighted.
Keywords Global assessment Freshwater crab
Diversity Crustacea Decapoda
Brachyura Species estimates
Introduction
Of the more than 6,700 known species of brachyuran
crabs, over 1,300 are tru e freshwat er crabs. True
freshwater crabs are regarded as those that have
adopted freshwater, semi-terrestrial or terrestrial
modes of life, and are characterized by their ability
to complete their life cycle independe ntly of the
marine environment. These crabs are currently
assigned to eight exclusively freshwater families—
Pseudothelphusidae and Trichodactylidae (Mexico,
Central and South America), Potamonautidae (Africa
and Mada gascar), Deckeniidae and Platythelphusidae
(East Africa), Potamidae (North Africa, southern
Europe, Asia), Gecarcinucidae (Seychelles, Asia),
and Parathelphusidae (Asia, Australasia) (Martin &
Davis, 2001). Wholly or primary freshwater taxa
undergo direct development in which the large, yolky
eggs hatch directly into juvenile crabs. Crabs found in
Guest editors: E. V. Balian, C. Le
´
ve
ˆ
que, H. Segers &
K. Martens
Freshwater Animal Diversity Assessment
D. C. J. Yeo (&) P. K. L. Ng
Department of Biological Sciences, National University
of Singapore, 14 Science Drive 4, Singapore 117543,
Republic of Singapore
e-mail: darrenyeo@nus.edu.sg
N. Cumberlidge
Department of Biology, Northern Michigan University,
Marquette, MI 49855, USA
C. Magalha
˜
es
Instituto Nacional de Pesquisas da Amazo
ˆ
nia, Caixa
postal 478, Manaus 69011-970 Amazonas, Brazil
S. R. Daniels
Department of Botany and Zoology, University of
Stellenbosch, Private Bag X1, Matieland 7602,
South Africa
M. R. Campos
Instituto de Ciencias Naturales, Universidad Nacional de
Colombia, Apartado Ae
´
reo, Bogota 103698, Colombia
123
Hydrobiologia (2008) 595:275–286
DOI 10.1007/s10750-007-9023-3
freshwater also include numerous euryhaline species
or secondary freshwater species from primarily
marine brac hyuran families (e.g. Sesarmidae, Var-
unidae, Hymenosomatidae). Although these
freshwater species are fully adapted to freshwater/
terrestrial living, most do not have direct develop-
ment in their life cycle (though highly abbreviated
development occurs in some) and most possess one or
more larval stages. The diversity of these taxa is also
assessed in this chapter (Tables 1 and 2), but the
emphasis will be placed on the true freshwater crabs.
Freshwater crabs belong to the Order Decapoda, the
crustacean group that also includes lobsters, prawns,
crayfish and hermit crabs, which share the character-
istic presence of five pairs of thoracic legs (pereiopods).
In freshwater crabs the first pereiopods are modified as
pincers (chelipeds), and the remaining four pairs are
relatively unspecialised walking legs (Fig. 1). The
general body plan of freshwater crabs consists of a
head, thorax and abdomen, with the head and thorax
(cephalothorax) covered by a broad carapace, and the
abdomen reduced, flattened and flexed under the
thoracic sternum. In adults, the male abdomen is slim
and narrow, and is either triangular or T-shaped, while
the female abdomen is broad and round and covers
nearly the entire thoracic sternum. Adult males bear
two pairs of abdominal appendages (pleopods) that are
modified into copulatory structures known as gono-
pods. Gonopod structure is taxonomically important,
especially because the external morphology of fresh-
water crabs tends to be rather conservative (see Ng,
1988; Cumberlidge, 1999, for details).
Freshwater crabs are found in the tropics and
subtropics in most parts of the world, and occur in a
wide variety of aquatic and terrestrial habitats. These
decapods are present in almost all freshwater bodies,
from clear, fast-flowing montane streams to sluggish
lowland rivers and streams, as well as in peat and
freshwater swamps, stagnant ponds and rice fields,
and even in pools in tree holes and leaf axils. A fair
number are also adapted to live in caves. Among the
primarily aquatic freshwater crabs, some (e.g. pota-
mids) are entirely adapted to living in fresh water,
and are not thought to be able to survive for long in
salt water, while others (e.g. parathelphusids) are
more tolerant of saline conditions, and can survive
immersion in salt water for short periods of time.
Terrestrial species may occur well away from
permanent freshwater sources, either moving among
the forest floor litter or, in some cases, even climbing
trees (Ng, 1988; Ng & Tay, 2001; Cumberlidge et al.,
2005). These freshwater crab species do not require
regular immersion in fresh water and can obtain
water either from food, from drinking dew or casual
water, or by capillary or osmotic uptake from moist
substrata. In the present chapter, such species are also
categorised as ‘‘freshwater-dependent’’ species (see
later; Table 1).
Freshwater crabs are primarily nocturnal, prefer-
ring to remain hidden during the day in sheltered
places and foraging mostly at night. They are mos tly
omnivorous scavengers, mainly feeding on plant
matter, but some are opportunistic carnivores, feeding
either on live prey such as fish and praw ns or on dead
animals that they encounter (Ng, 1988; unpub.), and
cannibalism is not uncommon (unpub.). Crabs them-
selves also constitute an important food resource for
many species of fishes, birds, caymans, turtles and
mammals (see Ng, 1988; Magalha
˜
es, 2003).
Diversity and endemicity
Known global diversity
There are currently a total of 238 genera and 1,476
species of known freshwater crabs from 14 families
(including 1,306 true freshwater crab species in eight
families: Pseudothelphusidae, Trichodactylidae,
Potamonautidae, Deckeniidae, Platythelphusidae, Pota-
midae, Gecarcinucidae and Parathelphusidae) (as of 1st
August 2006). The species and genus diversity of
primary as well as secondary freshwater species are
listed by zoogeographical regions (sensu Cox, 2001) in
Tables 1 and 2, respectively. The total number of
species or genera of certain families listed in the last
column of Tables 1 and 2, respectively, do not tally
with the sum of species or genera from each zoogeo-
graphical region because some taxa occur in more than
one region (see later, Tables 1 and 2 footnotes).
Table 1 also lists separately the number of
‘‘freshwater-dependent’’ species (WDpt). In the
context of the present volume, our assessment of
the freshwater crab species required grouping
them into two broad ecological categories to reflect
their different habitat preferences and degrees
of their association with freshwater habitats, viz.,
‘‘real aquatic’’ species and ‘‘freshwater-dependent’’
276 Hydrobiologia (2008) 595:275–286
123