Easy win species

Module 2: Version 1, April 2007 (Richard Chadd)

Introduction to this moduleWhile some species

need a bit of work (and

time) to identify, there

are a great many which

a r e i n s t a n t l y

recognisable, or, with a

quick check with a

microscope or hand

lens, can be identified

in a trice. The Water

Stick Insect, Ranatra

l i n e a r i s ( L i n n . )

(Heteroptera: Nepidae),

pictured on the left,

looks like no other British insect from either the terrestrial or aquatic

environment. There is really no excuse to stop at Family level if you come

across one.

The purpose of this module is, therefore, to give you some guidelines to

allow you to recognise where you can get the 'easy wins' - taxa which need

not result in additional time for analysis to species level. Ultimately, it would

be a benefit to the environment to do everything you can to the lowest

possible level, but of course, time can be an issue.

The module is manifestly not designed to be an identification guide. It aims to tell you which taxa are worth a quick stab at (and which are not)

and which features you need to look at to undertake either recognition or

swift identification. You're expected to do some work. For example, you

might take, say, a leech and give it the once over, to decide if you can easily

identify it and, if you can, which feature(s) you need to look at to tell you

what it is. This module gives you the starting-point to make this assessment

- the actual identification is up to you. It isn't comprehensive: some, more

tricky families (e.g. hydrobiid gastropods) are left out. Anything not

mentioned in this module will be covered in the relevant taxon-specific

module (Module 10, in the case of Hydrobiidae).

You'll need access to much of the mandatory literature outlined in the

introductory leaflet (the ones with asterisks against them) to do this. The

relevant guide is referenced at the beginning of each section.

MODULE 2: RAPID IDENTIFICATION OF SPECIES (AND RECOGNITION OF DISTINCTIVE TAXA) - BY RICHARD CHADD


INTRODUCTION CONTINUED

Page 2 of 41

Within each section, there are mandatory exercises, which will be marked

by your tutor. You can submit them by printing out this workbook and filling

in the appropriate spaces by hand (but please add your name to the front of

the workbook), or you can use the template appended to the introductory

part and send completed exercises by email. There are also occasional self-

assessment exercises, which are not mandatory and do not contribute to

your certification, but may be helpful in understanding a principle or

technique. The module is loosely arranged in taxonomic order, starting with

the 'lower' taxa (flatworms, leeches, etc.) and moving up through the

Orders of arthropods.

This module contributes the second 50% of the mark towards the ‘Basic

Level’ of certification.


SECTION 1: FLATWORMS, LEECHES AND GASTROPOD MOLLUSCS

Page 3 of 41

For this section, you'll need a copy of the FBA guides to (1) triclads (Reynoldson & Young, 2000), (2) leeches (Elliott & Mann, 1979) and (3) gastropods (Macan, 1977). The "Illustrated Guide to Molluscs" (Janus, 1965) would be extremely helpful, too (see introductory leaflet, pages 5 and 6).

There are only 12 species of freshwater triclads found in Britain and

Ireland, which makes species-level identification a reasonably

straightforward proposition. When you consider that two of them

(Bdellocephala and Phagocata woodworthi Hyman) are rather rare and two

(P.vitta (Dugès) and Crenobia) are stenotherms - restricted to cool waters in

uplands and close to springheads - the job becomes that little bit easier.

You're unlikely, for example, to find P.woodworthi outside of Loch Ness or

either of the stenotherms in a large river in the lowlands.

Virtually all of the triclads can be separated with ease just by looking at:

1. Eyes (number, arrangement/position and separation);

2. General colour (and distribution of pigment, if any);

3. Shape (including possession of 'tentacles').

The only major sticking point comes in identifying Polycelis nigra (O.F.

Müller) and P.tenuis Ijima, in which you cannot rely upon colour for

separation of the two species. But all members of the Genus: Polycelis

have multiple eyes arranged in a border around the 'head' (all of the other

triclads have two) and P.felina has tentacles on its 'head'. So, identification

of the latter and separation of the co-operating taxon group of P.nigra/tenuis from all of the other triclads is easy.

So, check the eyes, then the colour, then see if it has tentacles on its head

and/or what general shape it is. Comparing against the pictures in the front

of the FBA guide may well crack it for you. It may be wise to make a quick

reference to the key just to make sure. You can confuse Planaria torva (O.F.

Müller) with one of the larger Dugesia, or a small Dendrocoelum with P.vitta

unless you follow the key feature on degree of separation of the eyes.

Live material is much easier to identify, but there is a key you can apply to

preserved triclads on page 48 of the FBA guide.


EXERCISE 1: IDENTIFY A TRICLAD

Page 4 of 41

This mandatory exercise is worth 5 points.

Find a triclad of any family (Planariidae, Dugesiidae or Denrocoelidae). This

should preferably be a live one - you'll find identification much easier. In the

space below, either attach a photograph (or more than one, if necessary) or

make a sketch of your specimen. The sketch needn't be of the whole

animal, just the diagnostic features, if you wish. Write down which species you think it is (or species group in the case of P.nigra/tenuis). Also write

down why you believe it to be this species (your 'diagnosis'), with arrows

pointing to the relevant bits if you feel it necessary to do so.

Complete exercise 1 in the space below or use the template appended to

the introductory leaflet.

Mark = / 5


SECTION 1: CONTINUED

Page 5 of 41

There are 16 species of leech known to be resident in British freshwaters.

Like the triclads, this is not an especially scary number to deal with. Unlike

the triclads, however, some of them are not especially easy. The five species

in F: Erpobdellidae can be tricky, so are not covered in this module (but will

be in Module 3). On the other hand, the members of F: Glossiphoniidae (especially the common ones) are really very easy to recognise. There is only

one species in F: Piscicolidae, so identify the family and you've got the

species. Which leaves two species of F: Hirudinidae, which are also pretty

straightforward.

As with triclads, start with the eyes. Count them and note the arrangement.

• Eight eyes in four ranks of two, arranged so that a line through them makes a double chevron (like a Citröen badge) is an erpobdellid. Note the family and stop.

• Eight in a ring around the head is one of two hirudinids. • Six or eight eyes in two (roughly) parallel lines down the middle is one

of five glossiphoniids. In this arrangement, only Theromyzon tessulatum (O.F. Müller) has eight eyes.

• Four eyes is Piscicola geometra (Linn.) if they are in a square pattern, or Hemiclepsis marginata (O.F. Müller) (F: Glossiphoniidae) if the front two are closer together than the rear two

• Two eyes is one of two glossiphoniids.

Now look at the colour (this may change on preserved material, so be careful).

• Hirudinidae: Hirudo has two big red lines on the dorsal surface (it's also a Red Data/BAP species, so a "yahoo!" moment if you find it!), Haemopis is uniform grey/black.

• Six-eyed glossiphoniid: Glossiphonia heteroclita (Linn.) is bright amber or pinkish - almost invisible on a white background (and the front pair of its six eyes are closer together than the other four).

Is it firm, like a wine gum, or soft and squashy, like a jelly tot? This may be easier to tell in a live specimen

• A firm beast, with six eyes, is G.complanata (Linn.). The remaining two squashy glossiphoniids require examination for papillae on the dorsal surface (this will be covered in Module 3). N.B. Theromyzon is also squashy.

Does it have a callosity, like a tiny, hard 'plate' just behind the two eyes?

• Yes? It's Helobdella stagnalis (Linn.).



Page 6 of 41

In the four glossiphoniids with six eyes, the eyes may (rarely) be fused, and

there is also a rare 2-eyed species - Haementeria costata (Fr. Müller) - so be

careful!


EXERCISE 2: IDENTIFY A LEECH

Page 7 of 41


Find a leech of any family except Erpobdellidae. In the space below, either

attach a photograph (more than one, if necessary) or make a sketch of your

specimen. The sketch needn't be of the whole animal, just the diagnostic

features, if you wish. Write down which species you think it is. Also write


pointing to the relevant bits if you feel it necessary.


the introductory leaflet

Mark = / 5



Page 8 of 41

There are over 40 species of gastropod mollusc in fresh or brackish waters

in Britain. Some are quite tricky, especially when juvenile, and the taxonomy

is uncertain in others, but a fair chunk of the British list comprises species

which are common and easy to identify.

But which ones are worth a go, as an 'easy win'? Try these families:

1. Neritidae (there's only one species in Britain);

2. Valvatidae (beware of deficiencies in the key, of which more

below);

3. Acroloxidae and Ancylidae (the latter has been sucked into F:

Planorbidae by European taxonomists, but no matter);

4. Physidae (but only the native ones);

5. Lymnaeidae;

6. Planorbidae.

Starting with Valvata, then.

V.cristata Müller is blindingly obvious. Separating V.piscinalis (Müller) from

V.macrostoma Mörch is not at all easy, however, especially as the FBA

guide (Macan, 1977) allows you to identify juvenile V.piscinalis as V. macrostoma. The important point is that the latter is a Red Data species, which seems to be getting rarer, and you will only ever see it in weedy ditches draining old grazing marshes, water meadows and washlands, mostly in the south and east. You will never see it north of a line connecting the Wash to the Severn Estuary, and/or in any river, lowland or upland.

Look at the pictures below1: V. macrostoma is not just flattened, as it shows

in the FBA guide. In addition, the umbilicus is oval and clear of the whorl,

the aperture greatly overhangs the body whorl, so that practically the whole

end of the 'tube' can be seen from above, and the aperture is not entire (i.e.

Fig. 2: Valvata piscinalis (Müller, 1774)Fig. 1: Valvata macrostoma Mörch, 1864

1 And, if you have a copy, consult Janus (1965). If you haven't, you are strongly advised to obtain one!-



Page 9 of 41

the body wall pushes into it, so it doesn't form a perfect circle). 99.999% of

the time, a valvatid which isn't completely flat like V.cristata will be the

seriously common V.piscinalis. If you're in an ancient washland or some

such habitat, keep an eye out for the rarity. But get it confirmed if you find

it!

For Acroloxidae and Ancylidae (the latter family now subsumed into F:

Planorbidae), the situation is slightly more complicated than is shown in the

FBA guide and Janus. This is because of the introduction of a North African

species of ancylid, first found in the wild in 1976, called Ferrissia wautieri (Mirolli). Superficially, it looks like Acroloxus, but the tip of the shell in the

latter points backwards and to the left and in the former, backwards and to

the right (they look over their left and right shoulders, respectively). The tip

in Ferrissia is also a tad less pointy. Ancylus, of course, is high, like a Smurf

hat, and the tip points straight back. It is also oval from above, where

Ferrissia and Acroloxus are straight-sided.

Fig. 3: Ferrissia wautieri (Mirolli, 1960) (left) and Acroloxus

lacustris (Linn., 1758) (right)

Next to Physidae. Ignore any references to species identification of non-

native ones. The species resident in the UK are still uncertain, so if you get

a dark, solid-looking Physa sp., which isn't P. fontinalis (Linn.), leave it as G:

Physa. The two native British and Irish species separate easily on shell-

shape.



Page 10 of 41

Now Lymnaeidae. In broad terms, there are 7 species in Britain and

Ireland. Two of them - Lymnaea peregra (Müller) and L. palustris (Müller) -

are now considered aggregates of 2 species each, so the total is, strictly

speaking, 9. The subtleties of their identification will be covered in Module

10. For now, use the details in the FBA guide and Janus to identify the two

aggregated taxa. Two species - Myxas glutinosa (Müller) and Lymnaea (now

Omphiscola) glabra (Müller) are very rare. All the rest are very common and

easy to identify.

In all lymnaeids, shell-shape is the overwhelming diagnostic feature, so,

most of the time, your species identification will be a case of recognition -

you will know that it's Lymnaea stagnalis (Linn.) because it looks like it!

Further useful features are shell texture (sculpturing and thickness) and

whether the umbilicus is open or closed. The latter feature is very useful in

identifying the Dwarf Pond Snail Lymnaea (now Galba) truncatula (Müller),

which, unlike a juvenile L. peregra agg., L. palustris agg., or L. stagnalis has

an open umbilicus.

Most of the 14 resident British and Irish Planorbidae are reasonably easy to

identify. Unsurprisingly, some are easier than others. Armiger (now

Gyraulus) crista (Linn.), with its nautilus-like ridges and Bathyomphalus

contortus (Linn.) with its overlapping, tight coils and deep concavity

underneath can't really be mistaken for anything else (sometimes the ridges

on A. crista are rather smaller than the ideal specimen shown in the FBA

guide and Janus, but they are always visible). Gyraulus albus (Müller) has

'race-track' ridges running down the length of the whorls and tends to be a

dull white colour, G. laevis (Alder) looks superficially like G. albus without

the ridges and a mature Planorbarius is too big to be anything else!

So, as with all of the gastropods, get familiar with shell-shape and surface sculpturing (plus size) of the planorbids and it will soon become second

nature. Bear in mind that four of them are national rarities: Anisus vorticulus

(Troschel), Gyraulus acronicus (Férrusac), Segmentina nitida (Müller) and

Menetus dilatatus (Gould). Always get these confirmed if you think you've

found them, and familiarise yourself with known distribution and habitat. G. laevis is also rather uncommon.


EXERCISE 3: IDENTIFY A SNAIL

Page 11 of 41


Find a gastropod mollusc from any of the families listed on page 8 (or, if you

like a challenge, any family you like!). In the space below, either attach a

photograph (more than one, if necessary) or make a sketch of your

specimen. Write down which species you think it is. Also write down why

you believe it to be this species (your 'diagnosis'), with arrows pointing to

the relevant bits if you feel it necessary.


the introductory leaflet.

Mark = / 5


SECTION 2: LARGER CRUSTACEANS

Page 12 of 41

For this section you'll need a copy of the FBA guide to Malacostraca

(Gledhill et al, 1993)- see introductory leaflet, page 6.

Some malacostracan crustaceans can be quite tricky. Many are not,

including plenty of common ones.

The ones worth attempting for rapid identification are:

1. Asellidae

2. Crangonyctidae

3. Gammaridae (at least in terms of useful groups)

4. Astacidae (essential, to stay within the law!)

Starting with Asellidae, then. There are only 4 species in the British Isles.

One of these (A. communis Say) is only found in Bolam Lake in

Northumberland and another (A. cavaticus Schiödte) is entirely

subterranean. The other two are common and pretty ubiquitous and can be

separated with the utmost ease just by looking at the pattern on the head:

A. aquaticus (Linn.) has a dark head with two white spots, A. meridianus Racovitza, a similarly dark head with a single white, slightly irregular rectangle on it. This distinction works for 99% of the specimens

you will see (T. Gledhill, pers. comm.), but you should check other features

in the key from time to time, or if there is any doubt in your mind. If it has no

pigment at all (and no eyes) and you found it in a cave or mine, then it could

be A. cavaticus. Watch out for recently moulted A. aquaticus/meridianus

though - they can be white, but you should see some eyes.

Dealing with Gammaridae and Crangonyctidae together. There are two

species of Crangonyx in the British Isles. One (C. subterraneus Bate) is (bit

of a clue in the name!) subterranean, eyeless and rare. C. pseudogracilis

Bousfield is a common species and, when alive, can be distinguished from

Gammarus spp. by walking upright and being a translucent, bluish-grey

colour rather than the yellowish colour of Gammarus.

The dorsal surface (pleosome and urosome) of the abdomen is more or less

devoid of spines in Crangonyx (see Fig. 4 on the next page) and it has a

strongly serrated back edge to the basal segment of the legs it uses to walk

with (the pereopods). The latter features allow easy separation of the two

genera, even in dead material.



Page 13 of 41

Fig. 4: Posterior end of Crangonyx pseudogracilis Bousfield (top) and Gammarus pulex (Linn.) (bottom), showing the differences in the urosome.

It isn't especially easy to separate Gammarus spp., but, at the very least,

you should attempt to separate the brackish - water ones from the

freshwater ones, which is easy.

In the brackish ones, the eyes are an elongated kidney shape, twice as

long as they are broad (see the FBA guide, page 53). They are frequently

(but not always) stripy - the freshwater ones never have stripes. Also, the

brackish ones tend to be larger and spinier. A possibly unreliable distinction

in separating two of the more common brackish species is that, in G. tigrinus Sexton, the stripes are in the middle of each thoracic and

abdominal segment (see Fig. 5 on the next page). In G. zaddachi Sexton,

the stripes are at the junction between each segment. This always seems to

work when cross-checked against the key features. Even if you don't want

to go this far, producing a data point marked Gammarus sp. (brackish-water

species) could give you some very useful datasets.

Spines in Gammarus

Sparse, fine hairs in Crangonyx



Page 14 of 41

Fig. 5: Gammarus tigrinus Sexton. Note arrangement of the stripes and shape of the eye

Separating the ubiquitous G.pulex (Linn.) from G. lacustris Sars is not very

easy. The latter tends to be present in lakes, however, and very rarely in

flowing water. It is also a generally Northern species, so, in Great Britain at

least, is extremely unlikely to be encountered south of a line drawn from the

Wash to the Severn Estuary. Therefore, any non-saline Gammarus spp.

found in a river are, 99% of the time, going to be G.pulex. In the southern

counties of England, G. lacustris is even less likely and virtually impossible

in a riverine environment. So you can make a judgement on how low,

taxonomically, you want to go. Check key features using the FBA guide on

Gammarus spp. from lakes or from pools associated with rivers, though,

especially in the North and West.

Segment junction

Stripe



Page 15 of 41

There is a wealth of literature dealing with Astacidae. Rightly so, given the

increasing threat to native Austropotamobius pallipes (Lereboullet) by ever-

growing records of non-native crayfish. Always be very careful to confirm

your records by looking at as many features as you can. There are,

however, certain features particular to A. pallipes which give you a pretty

instant recognition in the field:

The sides of the rostrum converge from just in front of the eyes, like this;

In the non-native ones, the

rostrum is parallel - sided (apart

from in the Red Swamp Crayfish

(Procambarus) which is - well -

red…..)

The underside of the claws is pale and lighter than the upper sides (there

may be a faint pinkish bloom, so that the undersides are not necessarily

pure white).

There are horror-stories involving people dispatching A. pallipes in the

mistaken belief that they are never very big (i.e. "It's a big one - must be an

alien species" - splat!). This is balderdash. A. pallipes does not grow quite

as big as the more regularly encountered aliens, but it gets to 10 cm and

sometimes larger. Please do not kill or otherwise disturb crayfish on the

basis of size - rely on the rostrum and colour, especially on the claws.


EXERCISE 4: IDENTIFY A MALACOSTRACAN

Page 16 of 41


Find a fresh or brackish-water malacostracan from any of the families listed

on page 12 (or, if you like a challenge, any family you like!). In the space

below, either attach a photograph (more than one, if necessary) or make a

sketch of your specimen (or at least its diagnostic features). Write down which species you think it is. Also write down why you believe it to be this

species (your 'diagnosis'), with arrows pointing to the relevant bits if you

feel it necessary.



Mark = / 5

2 Like Baetis rhodani (Pictet), Ameletus has spines on the edges of the gills. Make absolutely sure you've got the right family!


SECTION 3: MAYFLY AND STONEFLY LARVAE

Page 17 of 41

For this section you'll need the FBA guides to (1) Ephemeroptera larvae (Elliott et al, 1988) and (2) Stoneflies (Hynes, 1977) - see introductory leaflet, page 6.

Both of these Orders are highly variable in terms of easy identification.

Some are enormously easy and some are fiendish.

Among the Ephemeroptera, it's worth trying to identify the larvae of:

1. Ameletidae (only one species in Britain);

2. Potamanthidae (ditto and then some - see below);

3. Ephemeridae;

4. Ephemerellidae.

In addition, some of the Baetidae, Heptageniidae, Leptophlebiidae and

Caenidae larvae are very obvious, at least in getting as far as genus or small

groups of similar species.

For Ameletus inopinatus Eaton, the only error you are likely to make is in

believing you have a specimen of Baetis sp.. 2Ameletus has small spines at

the hind corners of the abdominal segments, however, and (this is the

clincher!) a comb of bright orange bristles on the maxilla, as in the picture

below.

Fig. 6: Ameletus sp., showing maxillary comb

Maxilla

Comb



Page 18 of 41

For Potamanthidae, there is only one species in the whole of Europe -

Potamanthus luteus (Linn.). To leave this at Family level would be an

absurdity.

We only have three species of Ephemeridae in Britain. An examination of

the pigment pattern on the tergites is usually enough to separate them,

especially in large specimens. You'll need to move the gills out of the way to

do this, but they are very soft and feathery, so this is easily done. The shape

of the foreleg (tibia and femur) will confirm your diagnosis if there is any

doubt (see Elliott et al, 1988, Fig. 34).

There are only two Ephemerellidae in Britain. The presence of big spines

on the abdominal tergites easily separates Serratella ignita (Poda) from

Ephemerella notata Eaton (the latter has a hint of spines in the same place,

but these are very weak). A check of the gill-shape and pigmentation (see

Elliott et al, 1988, Fig. 35) and the stripy tails in Serratella will clinch it if you

are undecided.

In dealing with the rest of the Ephemeroptera, Baetidae are largely beyond

the scope of this Module (to go further, see Module 4). Baetis rhodani (Pictet) is, however, a very common species, now postulated to be a group

of microspecies. It's easily separated from the other baetids by removing a

gill and looking for spines along the edge under high power. They are best

seen at x 200 or above, but can be spotted as low as x 80, if the optics are

good enough. Be careful that you ensure that it is spines you are looking at,

with a clear circular base like a dinosaur tooth, not irregularities in the gill-

edge or hairs. Ameletus (F: Ameletidae) also have spines on the gill edge,

so don't confuse the two!

In the Heptageniidae, separation of the genera is easy:

1. Ecdyonurus spp. all have a backward-facing projection either

side of the pronotum;

2. Rhithrogena spp. have the first gills greatly expanded and

meeting underneath the body;

3. Heptagenia spp. (now incorporating Electrogena and Kageronia)

don't possess either of the features in (1) & (2)

Of the three, G: Rhithrogena is worth pursuing to species. The features are

quite subtle, but there are only two species, so it's worth a try (see Elliott et

al, 1988 pages 56 & 57)

A species of heptageniid which has been extinct in Britain since the 1920s,

Arthroplea congener Bengtsson, and is now considered a family in its own

right (Arthropleidae), is worth noting, as it is instantly recognisable in having

huge, feathery maxillary palps. Keep an eye out for it (especially in big rivers

like the Thames) - it might reappear some day!



Page 19 of 41

One of the members of F: Leptophlebiidae is enormously easy.

Habrophlebia fusca (Curtis) is the only species with multiple-branching gills,

like little trees. Leptophlebia and Paraleptophlebia are easy enough to

genus, just using gill-shape. Beyond genus, it gets trickier.

F: Caenidae is generally quite hard. The rather rare Brachycercus harrisella

Curtis is, however, unmistakable, with three 'horns' on its head and blade-

like edges to the abdominal segments. A common species group,

consisting of Caenis luctuosa (Burmeister) and C. macrura Stephens

(known as C. luctuosa group) can be easily separated from all other caenids

in possessing a deep notch in the last abdominal sternite. If the notch is

very shallow, or is just a slight concavity, it could be C. pseudorivulorum Kieffermüller or C. pusilla Navas, so beware!


EXERCISE 5: IDENTIFY A MAYFLY LARVA

Page 20 of 41


Find a mayfly larva from any of the families listed on page 17 (or, if you like

a challenge, any family you like!). In the space below, either attach a


specimen (or at least its diagnostic features). Write down which species you think it is. Also write down why you believe it to be this species (your

'diagnosis'), with arrows pointing to the relevant bits if you feel it necessary.



Mark = / 5

3 A third, Chloroperla (= Xanthoperla) apicalis Newman is probably not a resident species in the UK, but occurs on the Continent in large lowland rivers. In such habitats, if you have a specimen which doesn't seem to fit the key, consider that it could be the Continental one, but bear in mind that this is hugely unlikely.



Page 21 of 41

For the larvae of Plecoptera, it's worth trying to take the following Families

to species:

1. Perlidae;

2. Chloroperlidae.

At least some of F: Taeniopterygidae and Leuctridae are also worth

attempting. F: Nemouridae are generally rather tricky to take to species, but

can be mind-blowingly easy to take to Genus level.

Perlidae are generally obvious by virtue of size, and their possession of

pleural gills on the thorax ('hairy armpits') separates them from the larger

Perlodidae.

There are only two species and colour alone will generally do the job.

Dinocras cephalotes (Curtis) tends to be a drab red-brown to dark brown,

with a rather indistinct yellowish-grey pattern. Perla bipunctata Pictet, by

contrast, is black with a bold yellow pattern on it. If you are unsure (and the

bold pattern in Perla may fade in preservative), take a look under the head.

The submentum (the broad plate shaped like a kind of wobbly crescent

which dominates the underside of the head) has a pair of rounded corners

facing forwards (the 'tips' of the crescent). In Dinocras, the tips have a

groove (suture) cutting them off from the rest of the submentum. In Perla,

there is no suture. Dinocras also has a much wider pronotum, but this is a

slightly relative distinction.

In the Chloroperlidae, you are only likely to see two species3. The larvae

are quite easy to separate; Chloroperla tripunctata (Scopoli) has an obvious

'M-line' on the top of the head in front of the eyes - an M-shaped boundary

between the darkly-pigmented back of the head and pigment-free front.

Chloroperla torrentium (Pictet) has no such M-shape to this boundary - it's

more-or-less a straight line, and the pigmented area covers most of the top

of the head. The pigment may fade in preservative, but you can still use the

epicranial suture (the groove running in a Y or V-shape from the back of the

head to in front of the eyes). In C. tripunctata it has an obvious stem, so the

suture is clearly Y-shaped. In C. torrentium, the stem is very short, or

absent, so the suture looks like a V. Also, the fringe of hairs around the

pronotum is incomplete in C. tripuncata.



Page 22 of 41

Chloroperla torrentium (which some authors place in G: Siphonoperla) is the

more common of the two species, but both can be regarded as common,

especially in upland areas.

The only easy member of F: Taeniopterygidae is Taeniopteryx nebulosa

(Linn.) (Aubert 1950). On top of the abdomen, each segment up to the 7th

one has a spike on its hind edge, facing backwards (see Fig. 7, below). It

has been called the 'Stegosaurus Stonefly'.

In addition, on the underside of the thorax, the base of each leg has a 3-

segmented gill. There is no other stonefly looking anything like this.

The specimens found in the UK belong to an endemic subspecies,

Taeniopteryx nebulosa brittanica (Hynes), which is found nowhere else in

the world.

Fig. 7: Taeniopteryx nebulosa (Linn.)(Aubert). Note the 'Stegosaurus spikes' on the top of the abdomen

The first two Leuctridae in the key are quite easy to spot. L. geniculata

(Stephens) has little triangular spiky bits on the basal segments of the

antennae (see Fig. 8, below). It is also by far the biggest of the Leuctridae

when full grown (up to 11 mm - the rest don't get bigger than 8 mm) and

has a rather broad head which makes it look a bit 'goaty'. L. nigra (Olivier) is

bright orange/yellow and is covered in long fine hair, especially around the

edge of the pronotum.



Page 23 of 41

Fig. 8: The head of Leuctra geniculata (Stephens), showing antennal 'spikes'

You should attempt to take Nemouridae at least to Genus level: G:

Protonemura is unmistakable in having two bunches of three 'sausage gills'

under its 'chin'. G: Amphinemura has two bunches of filamentous gills in

the same place. Beyond genus, it becomes tricky, though. Without gills, it's

either G: Nemurella or G: Nemoura. Separation of nemourid species will be

covered in Module 4.


EXERCISE 6: IDENTIFY A STONEFLY LARVA

Page 24 of 41


Find a stonefly larva from either of the families (1) & (2) listed on page 21 (or,

if you like a challenge, any family you like!). In the space below, either

attach a photograph (more than one, if necessary) or make a sketch of your





Mark = / 5


SECTION 4: CADDISFLY LARVAE

Page 25 of 41

For this section, you'll need a copy of both FBA guides to caddis: (1) Edington & Hildrew (1995) and (2) Wallace et al (2003) see introductory leaflet, page 8. You would also find it extremely useful to have a copy of Wallace (2007) as a simple guide. The latter takes a similar approach to this module and you may be able to go further than the species outlined below.

Starting with caseless caddis larvae. With the exception of F: Ecnomidae,

which only incorporates one species, there are no families in which all of

the species are easy to identify. Some of the species in the following

families are worth a try, though:

1. Rhyacophilidae;

2. Philopotamidae;

3. Psychomyiidae;

4. Hydropsychidae.

Clearly, you'll have an easier job with specimens of a higher instar. Be

careful not to make mistakes with tiny larvae.

There is only one obvious species of Rhyacophila: R. munda McLachlan

has gills on the thorax with only one filament. Those on the abdomen have

four filaments. In the other three, trickier Rhyacophila spp., all of the gills

have lots of filaments (10-20 or more).

Two of the four species of Philopotamidae are rather easy. The front-edge

of the frontoclypeus - the hardened 'forehead' of the larva above the

membranous 'top lip' - is uneven (notched) in Chimarra marginata (Linn.)

and Philopotamus montanus (Donovan). In the former, the notch is deep

and wide and in the latter, shallow and V-shaped. Wormaldia sp. have a

smooth, rounded frontoclypeus, but it's difficult to separate the two

species.

Like Rhyacophilidae, only one species of the Psychomyiidae is obvious.

The common species Tinodes waeneri (Linn.) has a distinctive head pattern,

with the frontoclypeal apotome conspicuously darker than the rest of the

head and two pale egg-shaped blobs on the largely darkened pronotum, as

in Fig. 9, on the next page.



Page 26 of 41

Fig. 9: Tinodes waeneri (Linn.) - front end showing features of head and pronotum

Among the Hydropsychidae, there are two species which lack gills on the

underside of the 7th abdominal segment (fourth from the end). These are

Hydropsyche siltalai Döhler and Diplectrona felix McLachlan. H. siltalai differs from Diplectrona, however, in having pale spots on the top of its

head (frontoclypeal apotome), whereas the latter has a uniformly brown

head (and has a 'kink' in the edge of the frontoclypeus, around the eye, and

transverse sutures on the thorax as in figs.115 and 117 on page 45 of the

FBA guide).

Another easy one (which also lacks the spots of all of the nine Hydropsyche

spp. and has a pale brown head) is Cheumatopsyche lepida (Pictet). This

differs from all other hydropsychids in having a dense covering of long

bristles on the front edge of the pronotum. It also has a hairy head, but so

does H. bulgaromanorum Malicky. The latter was last found as an adult

near the R. Thames in 1926, so you're unlikely to turn it up, but you

shouldn't rely on the head bristles.

As with many of the caseless caddis, the head-patterns in Hydropsyche

spp. can be distinctive. Don't rely on them though - always check the key

features.

F: Ecnomidae only has one representative in Britain, Ecnomus tenellus

(Rambur). It's quite distinctive, with dorsal plates on all three thoracic

segments, like Hydropsychidae. Unlike Hydropsychidae, it has no gills on

the abdomen. Instead, it has a fringe of bristles along the side. It lives on

Egg-shaped blobs

Dark frontoclypeal apotome (contrasting with rest of head)



Page 27 of 41

large, bouldery substrates (occasionally in plants) in still or very sluggish

water, such as canals and large canalised rivers.

There are many more species of Cased caddis larvae to identify, which

makes the proposition slightly more scary. The FBA guide (Wallace et al, 2003) is excellent and uses lots of very clear features and jizz elements. The

jizz approach is taken further in the Field Studies Council simple guide

(Wallace, 2006), which means you can identify substantially more than you

would imagine. Module 5 will cover all the caddis larvae in much more

detail. For the purposes of this Module, have a try with the following:

1. Some of the Limnephilidae;

2. Odontoceridae (only one British species);

3. Brachycentridae (ditto);

4. Goeridae;

5. One of the Beraeidae;

6. Sericostomatidae;

7. Molannidae.

It is also easy to identify the so-called 'microcaddis' - Hydroptilidae - to

Genus level just by looking at the case alone (see Wallace, 2006, pages 52

and 53). Two of them can easily go to species taking this approach (see

Wallace, page 53).

The Limnephildae is a Family which tends to bring people out in panicky

sweats. Many are undoubtedly tricky, but a few are instantly recognisable,

even without going through the key. Ecclisopteryx guttulata (Pictet), a

species with single gills on the abdomen, has great big Gothic Death Metal

spikes between the eyes and the frontoclypeus (not hairs, but chunky

spikes with an obviously circular cross-section, so that it looks like it would

stick in a dartboard - see Fig. 10, below).

Fig. 10: Ecclisopteryx guttulata (Pictet), with its Goth-spikes. Be afraid!



Page 28 of 41

Ecclisopteryx is a locally common species in large stony rivers in the north

and west of Britain. Another very common and more widespread single-

gilled species, which also favours a stony substratum nearly always in

streams and rivers is Drusus annulatus (Stephens). It has an irregular stony

case, somewhat like a sericostomatid case but nowhere near as smooth.

The head is dark brown with a knobbly texture and is flat on the

frotoclypeus, and the pronotum is humped if you look at it from the side.

Another, less common but widespread species, Hydatophylax infumatus

(McLachlan) is immediately recognisable by having only a single sclerite at

the front of the metadorsum. All other limnephilids have two, nearly always

with setae (hairs) on them, or none at all, and the sclerite is replaced by two

groups of big, thick setae. The latter feature is characteristic of G: Apatania. This is not an easy genus to identify to species, however. It is now

considered a separate Family to Limnephilidae (= Apatanidae).

Just looking at the head pattern can reliably identify one common

limnephilid, Anabolia nervosa (Curtis), which has an 'anchor mark' (see Fig.

11, below).

Fig. 11: The head of Anabolia nervosa (Curtis), showing the 'anchor mark'

Be very careful that you don't confuse Anabolia with the one British

member of F: Odontoceridae, Odontocerum albicorne (Scopoli), which also

has a subtly different 'anchor mark' (see Fig. 12 on the next page).

Odontocerum has a sandy case (somewhat similar to Drusus, but a little

smoother & closed-off at the back with a large sand-grain), no prosternal

horn and the antennae are just about at the front edge of the head (in



Page 29 of 41

limnephilids, the antennae are roughly mid-way between the eye and the

front edge of the head).

Fig 12: The head of Odontocerum albicorne (Scopoli), showing the 'anchor mark'. Compare with Fig. 11 on the previous page.

Taking the F: Brachycentridae to species should, like Odontoceridae, pose

no problems, as there is only one British species, Brachycentrus subnubilus

Curtis. The Family is very distinctive, with a curve of metadorsal sclerites

and associated setae and ventral processes on the tibiae of the 2nd and

3rd legs.

F: Goeridae are not too hard. There are only three species. Goera pilosa

(Fab.) can be separated from the other two species of G: Silo Curtis by

looking at the shape of the frontoclypeal apotome and lateral sclerite on the

mesonotum (see Wallace et al, 2003, pages 69 to 71). G: Silo are not

especially easy to take to species, unless you have a mature larva of the

much more common S. pallipes (Fab.), which has three raised bumps on

the pronotum (these are usually paler in colour than the rest of the

pronotum).

Beraeidae are generally quite tricky, apart from mature specimens of

Beraeodes minutus (Linn.), which have a dark mosaic pattern on the

pronotum (see Fig. 13, below).

F: Sericostomatidae includes only two species. The very common

Sericostoma personatum (Spence) has the front corner of the pronotum

prolonged or sharply angled, the far less common Notidobia ciliaris (Linn.)

has a smoothly rounded corner here. The latter is associated with marginal



Page 30 of 41

vegetation in slow-flowing water - you will never see it in riffles, as you will

Sericostoma.

Fig. 13: The mosaic pattern on the pronotum of mature Beraeodes minutus (Linn.).

Finally, the very distinctive Family: Molannidae. They are very easily

separated looking at head-pattern alone, as in Wallace et al, 2003 (page

231). Added to this, Molanna albicans (Zetterstedt) is only found in Britain in

lakes in upland Wales and Scotland, never in rivers and never in lowland

England or Wales. M. angustata Curtis can occur in any sort of sluggish or

stillwater habitat in lowland England and rarely lowland Wales. They don't

co-exist.

Caddis larval identification will be taken further in Module 5. You are

strongly advised to get to grips with this fascinating, diverse and very useful

Order.


EXERCISE 7: IDENTIFY A CASELESS CADDISFLY LARVA

Page 31 of 41


Find a caseless caddis larva from one of the families listed on page 25 (or, if

you like a challenge, any family you like!). In the space below, either attach

a photograph (more than one, if necessary) or make a sketch of your






EXERCISE 8: IDENTIFY A CASED CADDISFLY LARVA

Page 32 of 41


Find a cased caddis larva from one of the families listed on page 27 -

preferably not the single-species families. If you like a challenge, try any

family you like! In the space below, either attach a photograph (more than

one, if necessary) or make a sketch of your specimen (or at least its

diagnostic features). Write down which species you think it is. Also write





Mark = / 5


SECTION 5: ALDERFLY LARVAE

Page 33 of 41

For this section, you will need a copy of the FBA guide to freshwater Megaloptera and Neuroptera (Elliott, 1996) - see introductory leaflet, page 7.

Larvae of the Alderflies (F: Sialidae) are really not very difficult to identify to

species-level. A check of the postoccipital sutures (a pair of grooves

running transversely on the dorsal surface at the back of the head) will

immediately separate the very common Sialis lutaria (Linn.) from the other

two British species. The head pattern and pattern of spots on the upper

surface of the abdomen are also diagnostic. In the remaining two species

(S. fuliginosa Pictet and S. nigripes Pictet), the pigmentation of the head is a

dead give-away.

S. fuliginosa is only ever found in moderately fast streams and the upper

reaches of rivers, often on sandy or gravelly substrata, whereas S. lutaria is

somewhat more widespread, but generally favours sluggish flows and

muddy substrata. S. nigripes is substantially rarer and can be found in large

or small lotic environments as well as lakes.

Fig. 14: Sialis lutaria (Linn.) (left) and S. fuliginosa Pictet (right) head-end showing post-occipital sutures. (N.B. The difference in colour may be an artefact of preservation, but the latter is frequently paler than the former).

Post-occipital sutures

Mark = / 5


EXERCISE 9: IDENTIFY AN ALDERFLY LARVA

Page 34 of 41


Find an alderfly larva. In the space below, either attach a photograph (more

than one, if necessary) or make a sketch of your specimen (or at least its






4 There is a new immigrant species of naucorid in Britain, Naucoris maculatus Fab. If you work near the Southeast corner of England, perhaps as far as the Wash to the North and the New Forest to the West don't assume that your species is Ilyocoris cimicoides. If you have an 'odd one' check Nau, B.S. and Brooke, S.E. (2005): Entomologists Monthly Magazine, 141, 193-196.


SECTION 6: TRUE BUGS

Page 35 of 41

For this section, you will need a copy of the FBA guide to aquatic Hemiptera: Heteroptera (Savage, 1989) - see introductory leaflet,

page 7.

Many of the Heteroptera are easily recognised just by looking at a picture.

If nothing else, you should be able to identify the species in the families

below in an instant by undertaking pure recognition (as outlined in Module

1, page 4):

1. Nepidae (there are only two of them - one is long & thin, the

other is short and broad);

2. Naucoridae4 (but be sure you don't confuse it with

Aphelocheiridae);

3. Aphelocheiridae (only one species in Britain - the other is in

Portugal!);

4. Pleidae (only one species in the whole of Europe);

So, apart from Nepidae (which are easy anyway), identify the family &

you've got the species.

You can also identify the following quite easily, using the key:

1. Notonectidae;

2. Corixidae (but only one or two of them).

The primary difficulty which seems to be encountered with Notonecta spp. is in separating Notonecta viridis Delcourt (previously N. marmorea viridis

Delcourt) from the rest. The primary key feature is the presence of

extensions on the side of the pronotum, so that it wraps around the eyes.

Seen from the side (see Fig.15 on the next page), the extensions form a

point. An additional 'jizz' feature is that the hemielytra (wing cases) look

rather matt in texture, as if they have been covered with icing sugar and the

insect is largely green underneath. It is usually noticeably smaller than the

other Notonecta.

To separate the rest, general colour is sufficient. There is the possibility of

an immigrant species of Notonecta appearing in Britain in the future - N.

lutea Müller - which is not in the key. It is unmistakable in having a pale

scutellum (the inverted triangle behind the pronotum, which is black in all


SECTION 6 CONTINUED

Page 36 of 41

the rest). It has spread through Europe to the Netherlands and is sure to

turn up eventually.

Fig. 15: Notonecta viridis Delcourt. Side view of pronotum, showing embracing extension

Some people find the Corixidae quite tricky, but the two species in the

Subfamily: Cymatiainae (characterised by having a uniformly brown

pronotum rather than a stripy one, and long, cylindrical front tarsi with a

'basket' of setae for catching prey) are easily separated by looking at the

colour of the wing cases. Again, a new species - C. rogenhoferi (Fieber) -

has appeared in the East of England. Watch out for it, at least in the East - it

has fine yellow speckles on the pronotum and hemielytra.


EXERCISE 10: IDENTIFY AN AQUATIC HETEROPTERAN

Page 37 of 41


Find a true bug, from any of the Families listed on page 35 (including

Corixidae if you want to give it a try, or any Family if you're feeling

adventurous). In the space below, either attach a photograph (more than

one, if necessary) or make a sketch of your specimen (or at least its




Complete exercise 10 in the space below or use the template appended

to the introductory leaflet

Mark = / 5


SECTION 7: WATER BEETLES

Page 38 of 41

For this section, you will need a copy of the FSC key to Water Beetles

(Friday, 1988) and FBA guide to Riffle Beetles (Holland, 1972) - see

introductory leaflet, page 7.

As in the terrestrial environment, the aquatic environment is known to be

associated with many species of Coleoptera. Quite a lot can be tricky, but

a few stand out.

Try the following:

1. Elmidae (adults and larvae);

2. Hygrobiidae (only one British species);

In addition, some of the Dytiscidae, Haliplidae and larger Hydrophilidae

should be attempted, as well as at least one of the Gyrinidae.

The Elmidae are generally recognisable as adults by looking at shape and

sculpture. Grooves, ridges and bumps on the pronotum and elytra make

them easily identifiable to species, with the exception of G: Oulimnius,

which needs genital dissection to diagnose the species. As larvae, they are

a bit trickier, although you should attempt to identify the common species

Elmis aenea (Müller), with its broad, rounded 'balloon' shape when seen

from above. It frequently has an orange stripe across it, too.

With Hygrobiidae, identify the family and you've got the species. They

screech if you mess with them and have a head which is noticeably

narrower than the front of the pronotum.

Which of the Dytiscidae are worth a go?

• Colymbetes fuscus (Linn.), which is on the front of the Friday (1988) key, has transverse reticulation, so that a water drop runs sideways off its back.

• Platambus maculatus (Linn.), which frequently turns-up in riffles, is a pretty distinctive, fairly large yellow and brown-striped species (colour can vary, though).

• All of the large species in SF: Dytiscinae (Dytiscus, Hydaticus, Acilius and Graphoderus) don't take much effort to identify, even with a hand lens in the field.

• You will continually come across specimens of G: Nebrioporus (formerly Potamonectes), especially the very common N. elegans (Panzer) pictured on the next page (Fig. 16). All of this genus are worth attempting.

• A brownish-red, fairly large species, which is so rounded that it looks like a pea with legs - Hyphydrus ovatus (Linn.) is common and distinctive.

With Dytiscidae, don't be put-off by size. Many of the SF: Hydroporinae are

seriously tiny, but very distinctively patterned or with other obvious

diagnostic features. Under a microscope, it will all become clear.


SECTION7 CONTINUED

Page 39 of 41

Fig. 16: Nebrioporus elegans (Panzer). A common and widespread species.

In the F: Haliplidae, Brychius elevatus (Panzer), unusual in favouring

running water, is extremely distinctive (see Friday (1988), page 22). The

common Haliplus lineatocollis (Marsham), with two long furrows on the

pronotum, is also very easy to spot.

There are two large, but rare Hydrophilidae, right at the beginning of the

key on page 93 of Friday (1988), which really can't be missed. Many of the

hydrophilids are blindingly obvious at Genus level. It can be tricky beyond

this, though.

Of the Gyrinidae, the hairy-faced Orectochilus villosus (Müller) is very

distinctive and unusual in favouring running-water habitats as an adult.

That's all the 'easy wins'. Any beetle is well worth attempting and it soon

becomes clear if you've picked a tricky one.


EXERCISE 11: IDENTIFY A WATER BEETLE

Page 40 of 41


Find a beetle. You may find a dytiscid (apart from G: Hydroporus) the best

option, but Elmidae are also generally good for this exercise. Try any Family

if you're feeling adventurous. In the space on the next page, either attach a




Complete exercise 11 in the space below or use the template appended

to the introductory leaflet


Page 41 of 41

And that's the end of this Module. Your overall mark will be written below. If

you pass, well done! If you get a distinction, even better.

You may now be tempted to leave it at that, but you will benefit greatly (and

get a higher level of certification) if you continue with the remaining

modules. It will help you to keep your hand in and, at the end of the whole

thing, all of the stuff in this module will just seem ridiculously easy to you.

You will be a fully-fledged species identification convert.

And it really is a rewarding thing to do.

/ 55 = %: Pass Fail

Documents

Easy win species