Balian E.V., L?v?que C., Segers H., Martens K. (Eds.) Freshwater Animal Diversity Assessment

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FRESHWATER ANIMAL DIVERSITY ASSESSMENT

Global diversity of butterﬂies (Lepidotera)

in freshwater

Wolfram Mey Æ Wolfgang Speidel

 Springer Science+Business Media B.V. 2007

Abstract In Lepidoptera, the subfamily Acentropi-

nae and Pyraustinae of Crambidae (Pyraloidea) and

the family Arctiidae (Noctuoidea) contain species

with true aquatic larvae, which live submerged during

larval development. In Pyraustinae and Arctiidae only

a few species exhibit an aquatic life-history. From the

latter, aquatic larvae are known from the Neotropical

genus Paracles. The number of aquatic Paracles

species is unknown. The Acentropinae are predomi-

nantly aquatic. They are distributed worldwide, and

reach the highest diversity in tropical regions of South

East Asia/Malesia and in the Neotropical Region. At

present, the Acentropinae include a total of 50 genera

and 737 described species. All genera, assigned to the

subfamily, are listed in a table, and the numbers of

included species are indicated. The taxonomy and

phylogeney of the genera are inadequately known.

The species have a minor economic importance,

however, they are very sensitive to degradation of

water qual ity and habitat destruction.

Keywords Lepidoptera  Acentropinae  Pyraloidea 

Arctiidae  Diversity  Distribution  Taxonomy 

Genera  Species numbers

Introduction

For an outsider it is surprising to learn that there are

indeed some Lepidoptera which are aquatic. Even for

limnologists or aquatic entomologists aquatic moths

do not belong to the well known and instantly

recognised types of aquatic insects. There is a speci al

reason for the poor recognition of aquatic Lepidop-

tera: the handling of the adult moths during sampling

and processing differs com pletely from the methods

used for other freshwater insects. The wing patterns

provide features, which are diagnostic at the species

level and, therefore, must be preserved intact, i.e. in a

dry state. As a consequence, individuals have to be

treated very carefully . Correct handling needs to use

killing jars, pins, pinning boxes, setting boards, and

insect drawers. These tools do not belong to the

regular equipment of aquatic entomologists or lim-

nologists. However, they are regularly used by

lepidopterists, who are usually specialised on certain

families. The study of aquatic Lepidoptera has always

been a subject of lepidopterists alone, who on the

other side, however, rarely have a limnological

background.

Today, the accumulated knowledge on aquatic

species has a focus on adults and is scattered in the

Guest editors: E.V. Balian, C. Le

que, H. Segers &

K. Martens

Freshwater Animal Diversity Assessment

W. Mey (&)

Museum fu

r Naturkunde, Humboldt-Universita

t Berlin,

Invalidenstr. 43, 10115 Berlin, Germany

e-mail: wolfram.mey@museum.hu-berlin.de

W. Speidel

Museum Witt, Tengstrasse 33, 80796 Munchen, Germany

123

Hydrobiologia (2008) 595:521–528

DOI 10.1007/s10750-007-9038-9

vast Lepidoptera literature, which is not easily

accessible for limnologists. Data on larvae is limited.

The larvae are caterpillars with a small degree of

intrageneric morphological differentiation, which

makes the identiﬁcation at the species level very

difﬁcult or impossible. The genera and species of the

Holarctic Region are rather well known. But Holarc-

tic species make up only a minority of the world

fauna in contrast to the overwhelming diversity of

taxa present in the tropics. Many species were only

provisionally assigned to a genus and remained there

up to now. Several aquatic species are exceptional

cases within their systematic groups. However, there

is a group of Lepidoptera, whose larvae are almost

exclusively aquatic; these are the so-called China-

Mark-Moths (Pyraloidea: Acentropinae). The larval

stages of most tropical species are undescribed, but

might be expected as aquatic. Information on the

biology of immatures is very poor. At this stage,

available data on the distribution, phylogeny and

taxonomy of aquatic moths are much too incomplete

to embark seriously into a deeper analysis of the

group concerning historical biogeography, faunal

changes, centres of endemicity, etc. However, a

summary of the currently recognised taxa and their

distribution on the planet can be provided. The

present account concentrates on families, which have

true aquatic species, i.e., with submerged living

larvae. These are the families Crambidae (Pyraloidea)

and Arctiidae. Some further families contain semi-

aquatic species. They are not considered here.

Species and generic diversity

Family Arctiidae: Arctiinae

The subfamily includes about 3,600 species (Hepp-

ner, 1991). One species is well-known for its aquatic

caterpillars: Paracles laboulbeni (Bar, 1873). It was

formerly placed in the genus Palustra. The species is

widely distributed in the Neotropical Region. The

caterpillars feed on submerged plants in sta gnant or

slow ﬂowing waters (Adis, 1983). They lack tracheal

gills. Respiration is mediated by air-holding hairs

forming a plastron on the dorsal side. The genus

Paracles is very speciose. It is unclear, whether P.

laboulbeni is the only aquatic species or whether

further congeners have aquatic immatures.

Family Crambidae: Pyraustinae

The subfamily is a mega-diverse group with over

7,000 species word-wide (Heppner, 1991), also

sometimes retained in a larger concept of Pyralidae.

A few species are reported to have aquatic larvae

(Buckingham, 1994):

Samea multiplicalis Guene

e, 1854—Neotropical

Region,

Niphograpta albiguttalis Warren, 1889—Neotrop-

ical Region.

Both species have been used in biological control

programme to suppress mass developments of aquatic

weeds in stagnant and running waters. In South–East

Asia there are several, hitherto unidentiﬁed species,

which were collected only close to running waters.

They form aggregations of adults on the underside of

boulders and overhanging rocks, a behaviour known

for aquatic moths. The larvae of these species are

supposed to be aquatic, but have not been traced yet.

Family Crambidae: Acentropinae

The group is well known under its synonymous name

Nymphulinae. Heppner (1991) has compiled species

totals for each of the over 300 subfamilies and

families of the Lepidoptera of the world. They were

tabulated according to major faunal regions whose

delimitations are essentially based on Darlington

(1957). According to his ﬁgures the Acentropinae

comprise 716 described species. During recent years

a number of new checklists, catalogues and taxo-

nomic change s were published, which provide

current ﬁgures for Acentropinae of nearly all faunal

regions or continents: Henning (2003), Li et al.

(2003), Munroe (1983, 1995), Shaffer et al. (1996) ,

Speidel (2005), Speidel & Mey (1999), Yen (2004),

You et al. (2002). In addition, a large number of new

species have been described especially from the

Oriental Region in the last decade (Li et al., 2003;

Mey, 2006; Mey & Speidel, 2005; Speidel, 2003;

Yoshiyasu, 1987; You & Li, 2005; You et al., 2003,

etc.). Based on these publications and our own studies

a new synthesis was undertaken at the generic level.

We have used Heppner‘s scheme with slight changes:

the northern Mexican border line is the border of the

Neotropical Region and the Australian Region is

divided into a Newgui nean-Polynesian and proper

522 Hydrobiologia (2008) 595:521–528

123

Australian–New Zealand Region. The new ﬁgures are

summarised in Table 2. Up to date, the Acentropinae

encompass 737 species in 50 genera. Interestingly,

the counts are similar to Heppner‘s ones. In the past,

many more genera were included, mainly because of

superﬁcial resemblance of wing patterns of the adults.

They has been subsequently excluded, but this

process is not complete. Exclusion of misplaced taxa

and synony mies have not equalled the number of new

species descriptions since 1991 (Figs. 1, 2).

The counts for the faunal regions are not by type

localities. Thus, the problem of double counting of

species which are distributed in several faunal regions

has to be considered. The problem is notoriously

evident in the East Palaearctic and Oriental Faunal

Regions, which have a broad, common transition

zone. Widespread species were indicated for all

faunal regions in which they occur, but recorded only

once in the ‘‘total’’ column of Table 2.

Phylogeny and historical processes

Lepidoptera are essentially terrestrial insects. Only a

tiny fraction of the 165,000 describ ed species can be

termed aquatic, which means that they have immature

stages that live under water. The adults are terrestrial as

in the majority of water insects. The conquest of the

aquatic environment by lepidopteran larvae is not that

astonishing as it may appear at ﬁrst glance. Larvae of

Lepidoptera—the caterpillars—have an enormous

adaptive potential (Scoble, 1992). Primitive species

like Micropterigidae or ancestral Pyraloidea are detri-

tivorous and moss feeders sometimes are associated

Fig. 1 (A) Eoophyla boernickei Mey, 2006, male (Borneo), (B) Parapoynx leucographa Speidel, 2003, male (Borneo) (C)

Margarosticha spec., male (Sulawesi), (D) Paracymoriza spec., male (Borneo)

Hydrobiologia (2008) 595:521–528 523

123

with fungi or animal matter (Munroe & Solis, 1998:

235). The larvae often live in a humid environment on

the ground. With the development and radiation of the

angiosperms in the Cretaceous a new food resource

became widely available. Caterpillars of early evolu-

tionary lineages started to use green-plant tissue as a

food source and became phytophagous. In a process of

co-evolution and radiation together with the angio-

sperms, the Lepidoptera were able to adapt to all plant

groups and developed a wide array of life histories,

forms and strategies which allowed them to exploit all

parts of a plant: leaves, stems , roots, bark, twigs,

ﬂowers, seeds, etc. Aquatic or semiaquatic plants,

being no excep tions, are hosts of a number of

lepidopteran species, too.

The caterpillars usually feed on green leaves or on

the periphyton in rocky habitats. The cuticule of

caterpillars has morphological preadaptions to some

kind of plastron respiration. With these larval

preadaptions it was only a small step in the evolution

from a wet terrestrial to a semiaquatic life history. It

is, therefore, not surprising that a transition to aquatic

or semiaquatic life occurred several times and

independently in different, unrelated taxa of Lepi-

doptera. Aquatic larvae are known to occur in the

mega-diverse families Crambidae and Arctiidae

(Table 1). There are probably more families with

aquatic representatives. The poor exploration and

knowledge of tropical Lepidoptera, especially of rain

forest areas with their huge variety of aquatic habitats

Fig. 2 Distribution of freshwater Lepidoptera species and genera by zoogeographical region (species number/genus number). PA—

Palaearctic; NA—Nearctic; NT—Neotropical; AT—Afrotropical; OL—Oriental; AU—Australasian; PAC—Paciﬁc Oceanic Islands

Table 1 Generic and

species diversity of

currently known

Lepidoptera taxa with

aquatic larvae

Superfamily/Family Subfamily Number of genera Number of species

Pyraloidea

Crambidae Acentropinae 50 737

Pyraustinae 2 2

Noctuidoidea

Arctiidae Arctiinae 1 1

524 Hydrobiologia (2008) 595:521–528

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Table 2 The genera of Acentropinae—their distribution

and diversity in the major Biogeographical Regions of the

world (PA = Palaearctic, NA = Nearctic, NT = Neotropical,

AT = Afrotropical, OL = Oriental, AU = Australasian, PAC =

Paciﬁc Oceanic Islands (Micronesia-Polynesia))

Genus PA NA NT AT OL AU PAc Total

Acentria Stephens, 1829 1 1 1

Agassiziella Yoshiyasu, 1989 2 10 12

Ambia Walker, 1859* 7* 7

Anydraula Meyrick, 1885 2 3* 5

Araeomorpha Turner, 1908 2 2

Argyractis Hampson, 1897 1 12 8* 21

Argyractoides Lange, 1956 12 12

Argyrophorodes Marion, 1957* 7* 7

Aulacodes Guene

e, 1854 35 3 38

Callilitha Munroe, 1959 22

Cataclysta Hu

bner, [1825] 1 9* 9* 2* 21

Chrysendeton Grote, 1881 3 16 19

Cryptocosma Lederer, 1863 1 1

Contiger Lange, 1956 1 1

Elophila Hu

bner, 1822 13 4 2 2 7* 6 31

Eoophyla Swinhoe, 1900 11 12* 54 73 142

Eoparargyractis Lange, 1956 3 3

Ephormotris Meyrick, 1933 2* 2 4

Eristena Warren, 1896 12 26 3* 41

Giorgia Clarke, 1965 1 1

Hemiloba Swinhoe, 1901 1 1

Hygraula Meyrick, 1885 2 2

Hylebatis Turner, 1908 11

Kasania Krulikowsky, 1910 1 1

Langessa Munroe 1972 1 1

Lathroteles Clarke, 1971* 1* 1

Margarosticha Lederer, 1863 2 13 15

Neargyractis Lange, 1956 1 7 8

Neocataclysta Lange, 1956 1 1

Neoschoenobia Hampson, 1900 1 1 2

Nyctiplanes Turner, 1937 1 1

Nymphicula Snellen, 1880 7 10* 22 7 46

Nymphula Schrank, 1802 4 1 2 2* 9

Nymphuliella Lange, 1956 1 1

Nymphulodes Hampson, 1919 1 1

Oligostigma Guene

e, 1854 7 2* 2* 11

Oligostigmoides Lange, 1956 1 5 6

Oxyelophila Forbes, 1922 1 7 8

Paracataclysta Yoshiyasu, 1983 1* 1 1 3

Paracymoriza Warren, 1890 11* 22* 4* 37

Parapoynx

bner,

[1825] 17

8 13 9* 16 22 76

Petrophila Guilding, 1830 15 82 97

Potamomusa Yoshiyasu, 1985 2 2

Hydrobiologia (2008) 595:521–528 525

123

suggests that we can expect further families with

aquatic members.

The most advanced adaptations to an aquatic

existence can be found in the pyraloid subfamily

Acentropinae (=Nymphulinae). The majority of

aquatic species belong to this subfamily. Hasenfuss

(1991) published a convincing scenario for the

evolution of the aquatic habit of Acentropinae.

According to the plant species or food resource, the

caterpillars developed a wide spectrum of adaptations

towards a semiaquatic and ﬁnally towards a fully

aquatic life: species wi th plastron respiration and

open tracheal system feed on ﬂoating or partly

submerged leaves, whereas species with tracheal

gills and closed spiracles are able to live on fully

submerged plants or are rock-dwellers in streams. A

comparative, taxonomic analysis of the genera on a

world-wide scale was not attempted so far, and thus,

makes the validity of some taxa questionable. Phy-

logenetic relations hips among genera were studied

only on a restricted geographical scale (cf. Speidel,

1984, 2005; Yoshiyasu, 1985). A subdivision of the

subfamily into two tribes was proposed by Lange

(1956). He included in Nymphulini the case-making

shredders and green-plant tissue feeders, and in

Argyractini the free living scrapers and web spinning

algae feeders. The division, however, was not found

to be an adequate reﬂection of phylogenetic relation-

ships (Munroe & Solis, 1998) and, thus, is not

followed here. Consequently, the genera are listed

alphabetically in Table 2.

The sister group relationship of the Acentropinae

is unresolved (Solis & Maes, 2002). Traditionally,

Acentropinae and Schoenobiinae have been consid-

ered closely related (Speidel, 1984; Munroe & Solis,

1998). They have semiaquatic larvae, which usually

feed as internal borers in the stems of water

monocots. Species of both subfamilies often occur

together in a wide range of aquatic habitats.

Present distribution and main areas of endemicity

As mentioned in the introduction, our inadequate

knowledge only allows rough conclusions from the

numbers in Table 2. The data show that tropical

regions have many more species than other faunal

regions. With approximately 40% of the world total

of described species, the peak diversity is in

Malesia, including the Paciﬁc islands from Micro-

nesia to Polynesia. This is mainly due to the

radiation of the genus Eoophyla in maritime South

East Asia and, even more pronounced, in New

Guinea. More than 140 Acentropinae species are

endemic to this islands and the Wallacea, which had

to be included into the Australian Region here in

Table 2. Eoophyla is the largest group in Acentrop-

inae. It is rather homogeneous but includes some

isolated forms that may necessitate the establishment

of separate genera. A comparably large genus in the

Neotropical Region is Petrophila, which also gets

into the Nearctic. It makes up nearly 50% of all

Neotropical species. In contrast to Eoophyla, the

radiation of Petrophila developed in a continental

setting. The poor ﬁgures for tropical Africa are in

accordance with ﬁgures from other Lepidoptera

groups. However, Africa south of the Sahara,

including Madagascar, is a poorly sampled continent

and should contain many more species. There are

two genera which occur in all faunal regi ons:

Table 2 continued

Genus PA NA NT AT OL AU PAc Total

Pseudolithosia Hampson, 1907 1 1

Strepsinoma Meyrick, 1897 2 9 11

Synclita Lederer, 1863 4 3 7

Synclitodes Munroe, 1974 1 1

Tetrernia Meyrick, 1890 1 1

Thysanoidma Hampson, 1891 2 2

Usingeriessa Lange, 1956 2 10 12

Number of genera 12 17 18 11 14 21 4 50

Number of species 81 49 216 64 169 170 9 737

Numbers with * denote unclear generic or subfamily associations

526 Hydrobiologia (2008) 595:521–528

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Elophila and Parapoy nx. Their species are mainly

inhabitants of stagnant waters.

Most genera have ranges restricted to one conti-

nent or to a single faunal region. The high number of

generic taxa in the New World and Australia appears

to demonstrate a higher diversity of evolutionary

lines on these continents. This can be genuine or is

merely an artifact due to the poor systematic inves-

tigation of the Afrotropical and Oriental faunas.

Human related issues

In general, aquatic moths are of little economic

importance. A few species are known to damage rice

in Asian countries: Parapoynx ﬂuctuosalis (Guene

1854), P. vittalis (Bremer, 1864) and P. stagnalis

(Zeller, 1852). Sometimes the injury can be serious,

but usually remains localised. The species are clearly

of less importance than rice stem borers of the

subfamily Schoenobiinae. The species from rice

paddies have a wide distribution. Some tropical

species were incidentally introduced together with

aquatic plants to other continents. In temperate

countries they are unable to adapt to the low winter

temperatures, and remain minor pests in greenhouses.

In warmer regions, some species have managed to

establish permanent populations in the ﬁeld. The

phytophageous caterpillars have been regarded as a

promising means for the biologi cal control of aquatic

weeds. They have been successfully used in the

suppression of Hydrillia and Elodea in Florida

(Buckingham, 1994).

Acentropine species from running waters are very

susceptible to water pollution and water channel

regulations. They are among the ﬁrst organisms

which would disappear when facing a drop in water

quality.

References

Adis, J., 1983. Eco-entomological observations from the

Amazon IV. Occurrence and feeding habits of the aquatic

caterpillar Palustra laboulbeni Bar, 1873 (Lepidoptera:

Arctiidae) in the vicinity of Manaus, Brazil. Acta

Amazonica 13: 31–36.

Buckingham, G. R., 1994. Biological control of aquatic weeds.

In Rosen, D., Bennett, F. D. & Capinera, J. L. (eds), Pest

Management in the Subtropics: Biological Control—a

Florida Perspective. Intercept Ltd, Andover, 737.

Darlington, P. J. Jr., 1957. Zoogeography: The geographic

distribution of animals. Wiley, New York, 675.

Hasenfuss, I., 1991. Evolution der aquatischen Larven und

Puppen der Acentropinae (=Nymphulinae/Crambidae/

Pyraloidea/Lep.). Verhandlungen der Deutschen Zoolog-

ischen Gesellschaft 84: 444.

Henning, S. F., 2003. Lepidoptera. In de Moor, I. J., J. A. Day

& F. C. de Moor (eds), Guides to the freshwater inver-

tebrates of Southern Africa, Vol. 8: Insecta III, 209.

Heppner, J. B., 1991. Faunal regions and the diversity of

Lepidoptera. Tropical Lepidoptera 2 supplement, 1: 85.

Li, Hou-Hun, P. You & S.-X. Wang, 2003. A systematic

study of the genus Eoophyla Swinhoe in China, with

descriptions of two new species (Lepidoptera, Crambi-

dae, Nymphulinae). Acta Zootaxonomica Sinica 28:

295–301.

Lange, H. W., 1956. A generic revision of the aquatic moths of

North America (Lepidoptera: Pyralidae, Nymphulinae).

The Wasmann Journal of Biology 14(1): 59–144.

Mey, W., 2006. Eine neue Art der Gattung Eoophyla Swinhoe,

1900 von Borneo (Lepidoptera: Crambidae, Acentropi-

nae). Entomologische Zeitschrift (Stuttgart) 116(2):

91–93.

Mey, W. & W. Speidel, 2005. Two new species of Eoophyla

Swinhoe, 1900 from continental South East Asia (Lepi-

doptera: Crambidae, Acentropinae). Bonner zoologische

Beitra

ge 53(1/2), 115–119.

Munroe, E., 1983. Pyralidae. In Hodges, R. W. (ed), Check List

of the Lepidoptera of America North of Mexico. E.W.

Classey Ltd., London, xxiv + 284.

Munroe, E., 1995. Nymphulinae. In Heppner, J. B. (ed), Atlas

of Neotropical Lepidoptera. Checklist: part 2, Gainesville,

liv + 243.

Munroe, E. & A. M. Solis, 1998. The Pyraloidea. In Kristen-

sen, N.P. (ed), Lepidoptera, Moths and Butterﬂie

Handbuch der Zoologie, Bd. 4, 35, Vol. 1. Handbuch der

Zoologie, Bd. 4, 35, de Gruyter, Berlin, 487.

Scoble, M. J., 1992. The Lepidoptera—form, function and

diversity. The Natural History Museum, London.

Shaffer, M., E. S. Nielsen & M. Horak, 1996. Pyraloidea. In

Nielsen, E. S., Edwards, E. D. & Rangsi, T. V. (eds),

Checklist of the Lepidoptera of Australia.—Monographs

on Australian Lepidoptera, Vol. 4. CSIRO, Canberra,

xiv + 529.

Solis, A. M. & K. V. N. Maes, 2002. Preliminary phylogenetic

analysis of the subfamilies of Crambidae (Pyraloidea,

Lepidoptera). Belgian Journal of Entomology 4: 53–95.

Speidel, W., 1984. Revision der Acentropinae des palaeark-

tischen Faunengebietes (Lepidoptera: Crambidae). Neue

entomologische Nachrichten 12: 157 pp.

Speidel, W., 2003. New species of aquatic moths from the

Philippines (Lepidoptera, Crambidae). Insecta Koreana

20: 7–49.

Speidel, W., 2005. Acentropinae. In Huemer, P. & Karsholt, O.

(eds), Microlepidoptera of Europe, Vol. 4: 33–68.

Speidel, W. & W. Mey, 1999. Catalogue of the Oriental

Acentropinae (Lepidoptera, Crambidae). Tijdschrift voor

Entomologie 142: 125–142.

Hydrobiologia (2008) 595:521–528 527

123

Yen, S.-H., 2004. Insecta: Lepidoptera, Cram bidae, Acen-

tropinae. In Yule, C. M. & Seng, Yong-Hoi (eds),

Freshwater Invertebrates of the Malaysian Region.

Academy of Sciences Malaysia, Kuala Lumpur, 861.

Yoshiyasu, Y., 1985. A systematic study of the Nymphulinae

and the Musotiminae of Japan (Lepidoptera: Pyralidae).

Scientiﬁc Report of the Kyoto Prefectural University 37:

162 pp.

Yoshiyasu, Y., 1987. The Nymphulinae (Lepidoptera: Pyrali-

dae) from Thailand, with descriptions of a new genus and

six new species. Microlepidoptera of Thailand 1: 133–

184.

You, P., H.-H. Li & K.-L. Chen, 2002. Catalogue of the

Nymphulinae and Musotiminae of China (Lepidoptera:

Crambidae). In Zhang, Z.-Q. (ed), Fauna of China, Vol. 4:

37–64.

You, P., H.-H. Li & S.-X. Wang, 2003. A taxonomic study of

the genus Eristena Warren, 1896 from China (Lepidop-

tera, Crambidae, Nymphulinae). Acta Zootaxonomica

Sinica 28(2): 302–306.

You, P. & H.-H. Li, 2005. Two new species of Nymphulinae

(Lepidoptera: Crambidae) from China. Entomotaxonomia

27(2): 131–134.

528 Hydrobiologia (2008) 595:521–528

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FRESHWATER ANIMAL DIVERSITY ASSESSMENT

Global diversity of hymenopterans (Hymenoptera; Insecta)

in freshwater

Andrew M. R. Bennett

 Springer Science+Business Media B.V. 2007

Abstract A summary of the known species of

aquatic Hymenoptera is presented. In total, 150

species from 11 families are recognized as aquatic

(0.13% of the total described species). This number is

likely an underestimate, because of the high percent-

age of undescribed species and a lack of knowledge

of host range and behaviour for most species. All

aquatic Hymenoptera are parasitoids. Many species

have relatively dense pubescence to trap air and

elongate, tarsal claws to grip the substrate, when

underwater. Most species are known from the Hol-

arctic and Oriental regions, but this is likely an

artefact caused by lack of knowledge of other regions

of the world. Aquatic behaviour has evolved inde-

pendently at least 50 times within the order.

Keywords Global diversity  Aquatic Hymenoptera

Introduction

The order Hymenoptera includes such well-known

insects as ants, bees and wasps. Hymenopterans

undergo complete metamorphosis and most species

may be recognized by possession of four membra-

nous wings (Fig. 1) coupled together with a series of

hook-like hairs known as hamuli (Goulet & Huber,

1993). The plesiomorphic biological condition is

herbivory (most sawﬂies) with transitions to parasi-

toidism and predation in more derived groups. Most

hymenopterans are parasitoids that develop in or on

one host arthropod, killing the host in the process

(Waage & Greathead, 1986). Some parasitoid species

parasitize eggs or pupae, but most oviposit in or on

host larvae.

Whereas almost all hymenopterans are terrestrial,

development in water has evolved independently in at

least 11 families (Table 1). All know n aquatic

Hymenoptera are parasitoids. A conservative ap-

proach has been adopted in this chapter such that only

species for which unequivocal evidence exists that

they spend at least some of their life in water are

included. This includes species in which female

adults enter the water to search for hosts, those with

endoparasitoid larvae inside aquatic larval hosts

(even if oviposition is terrestrial); and those in which

freshly eclosed adults must travel to the water’s

surface following pupation (even if they develop

inside stems of emergent vegetation). Only described

species with known hosts are included, except for a

few described species that lack host records, but

belong to genera that are unquestionably monophy-

letic and have a clear host range that includes only

aquatic hosts. Parasitoids that develop exclusively on

Guest editors: E. V. Balian, C. Le

que, H. Segers & K.

Martens

Freshwater Animal Diversity Assessment

A. M. R. Bennett (&)

Canadian National Collection of Insects, Agriculture

Canada, 960 Carling Ave., Ottawa, ON, Canada, K1A 0C6

e-mail: bennetta@agr.gc.ca

123

Hydrobiologia (2008) 595:529–534

DOI 10.1007/s10750-007-9036-y

terrestrial stages of aquatic insects are excluded (e.g.

in pupae of whirligig beetles or spongilla-ﬂies).

Species diversity

The order Hymenoptera has over 115,000 described

species (Gaston, 1993) and with estimates of one

million (Grissell, 1999; Ulrich, 1999) to 2.5 million

(Stork, 1996) total species, it may rival Coleoptera as

the most species-rich order. Table 1 includes 150

aquatic species (0.13% of all described speci es).

These ﬁgures have been compiled mainly from

discussions with colleagues, from databases (Noyes,

2002; Yu et al., 2005) and from surveys of aquatic

species for the Nearctic (Bennett, in press) and

Palaearctic (Hedqvist, 1978) regions. Accordingly,

most aquatic species in this chapter are Holarctic, but

this is likely an artefact caused by poor sampling in

other regions of the world and little or no knowledge

of biology for the vast majority of species. This lack

of knowledge makes it practically impossible to

predict how many species of aquatic Hymeno ptera

might exist, especially considering that many aquatic

species belong to genera that are predominantly

terrestrial (i.e. knowledge of biology at the generic

level does not always help predict existence of

aquatic species ). The use of water-ﬁlled yellow pan

traps placed around water or on emergent rocks in

water indicates that a great many more water-

dependent species may exist, but until host associa-

tions and/or observations of aquatic behaviour are

made, thes e species cannot be conﬁrmed as truly

aquatic. The number of conﬁrmed aquatic species and

genera in each biogeographic region are summarized

in Tables 1 and 2 and Fig. 2.

Aquatic Hymenoptera are known from six super-

families and 11 families (Table 1). The two largest

families, Ichneumonidae and Braconidae, have the

two greatest numbers of aquatic speci es: 39 and 26,

respectively. Within the Ichneumonidae, species in at

least ﬁve genera appear to be exclusively aquatic:

Agriotypus Curtis (Agriotypinae) on Trichoptera and

Rhachioplex Bischoff (Campopleginae), Pseude rip-

ternus Viereck and Tanychela Townes (both Cre-

mastinae) and Apsilops Fo

rster (Cryptinae) on

Lepidoptera. The braconid genus Ademo n Haliday

(Opiinae) is almost exclusively associated with

Hydrellia spp. larvae in emergent vegetation. Next

in richness of aquatic species are two families of egg

parasitoids: Trichogrammatidae (22) and Scelionidae

(17). Centrobiopsis Girault, Hydrophylita Ghesquie

and Prestwichia Lubbock (Trichogrammatidae) have

only aquatic species and Pseudanteris Fouts, Thoron

Haliday, Thoronella Masner and Tiphodytes Bradley

(Scelionidae) are all aquatic. The remaining families

have 12 or fewer aquatic species recorded within

each of them. Caraphractus cinctus Walker (My-

maridae), a parasitoid of dytiscid beetle eggs, has

been studied extensively and is known to swim with

its wings and mate inside submerg ed eggs (Jackson,

1966), although both of these habits are unusual for

the order. Most aquatic femal e wasps walk along the

substrate when searching for aquatic hosts and mate

out of water. The four species of Aspidogyrus

Yoshimoto (Figitidae) are endemic to Hawai i and

parasitize ﬂy larvae in str eams (Beardsley, 1992).

Finally, Anoplius depressipes Banks (Pompili dae) is

the only wasp known to parasitize ‘‘non-insects’’

(water-dwelling pissaurid spiders of the genus Dolo-

medes Latreille) and the only one known to move its

hosts to land prior to ovipo sition (Roble, 1985).

Aquatic Hymenoptera parasitize at least 25 insect

families in the orders Odonata, Hemiptera, Megalop-

tera, Coleoptera, Diptera, Lepidoptera and Trichop-

tera. No cases of aquatic hyperparasitism are yet

known. Most aquatic Hymenoptera have been

Fig. 1 Agriotypus gracilis Waterston (Hymenoptera: Ichneu-

monidae) female habitus. Scale bar = 1 mm

530 Hydrobiologia (2008) 595:529–534

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