CUMACEA - NMBAQC

NMBAQC workshop 2010 

CUMACEA 

Identification guide to British cumaceans 

Salma Shalla 

July 2011 

Atlantistylis borealis Shalla and Bishop 2005

Table of Content 

Introduction 3 

Morphology 6 

Sexual dimorphism 13 

Biology 14 

Classification 16 

Key to the families 16 

Family DIASTYLIDAE 19 

Family: LAMPROPIDAE 27 

Family PSEUDOCUMATlDAE 32 

Family BODOTRIIDAE 35 

Family NANNASTAClDAE 39 

Family LEUCONIDAE 45 

References 46 

2

Introduction 

Cumacea are a very distinctive order of the Class Malacostraca, in the Superorder Peracarida, 

distributed from the intertidal zone to the deep sea. Oniscus scorpioides (later re-named 

Diastylis scorpioides) was the first cumacean to be described, in 1780. At that time, many 

scientists thought that cumaceans were a larval stage of decapods. In 1846, they were 

recognized as a separate order by Krøyer. Twenty-five years later about fifty different species 

had been described. Since then, the number of known species has dramatically increased, and 

is still on the rise. In 1976 Jones listed 885 described species, in 1997 Watling and McCann 

listed over 1200 species and currently there are more than 1,593 described species (Anderson, 

2010). Although that increase was largely due to the species described from the deep-sea and 

Antarctic expeditions, nevertheless many new species were also discovered in shallow 

waters, especially in tropical areas. 

Cumaceans are small infaunal crustaceans, generally 1-10mm in length, although some 

species can reach up to 3.5cm. Typical cumaceans are easily recognizable by the combination 

of the following features (Figure 1): an inflated carapace, consisting of the head fused to at 

least the first three thoracic somites; anterior margin of the carapace usually extending in 

front of the head as a pseudorostrum; second antenna lacking an exopod; pereon composed of 

five free thoracic somites; pleon slender and composed of six somites ending in a forked tail. 

The telson may be present, reduced, or incorporated into the last abdominal somite. 

All the British species are marine, scarcely penetrating into estuaries. Elsewhere, the group is 

mainly marine, with only a few adapted to brackish and fresh waters. Relatively few live 

between tidemarks while many species are to be found in shallow water offshore, especially 

in the tropics, but they are also common in the deep sea, with a few recorded from below 

7000 m. 

The British cumaceans included by Jones (1976) were those recorded from the continental 

shelf within 20 miles of the British coasts and down to 200m depth, and comprised 41 

species. An additional 32 species which occur on the upper slopes down to 500m to the west 

of the British Isles are included here. The aim of this work is to update Jones (1976), so most 

of the keys are adapted from Jones. A few of the figures were also adapted from Sars (1900). 

History of cumacean taxonomy in the Northeast Atlantic 

Exploration in the deep North East Atlantic started with the “Lightning” cruise in the summer 

of 1868 and the “Porcupine” cruises in the summers of 1869 and 1870, led by Wyville 

Thomson, a Professor at Edinburgh. The cruises took place in the areas lying to the north and 

west of Britain and the Iberian Peninsula. The Rev. A. M. Norman (1879) described 30 

species of cumaceans from the „Lightning‟, „Porcupine‟ and „Valorous‟ expeditions, of 

which 9 were new species, and 2 new genera. On the basis of these cruises, and with the cooperation 

of the Royal Navy, the pioneering voyage of H.M.S. “Challenger” took place 

between 1872 and 1876 partly in the Atlantic but also in the Pacific and Southern Ocean. 

This was co-organised and led by Wyville Thomson. Fifteen new species of cumaceans were 

obtained during the Challenger voyage (Sars, 1887). 

Calman (1905) published a description of the cumaceans of the West Coast of Ireland taken 

by the “Helga” down to 400 fathoms during the years 1899-1904. Deeper stations produced 

3

icher yields (18 and 19 species). In total 48 species were identified, nine being regarded as 

new species, of which three represented new genera and one a new family. 

The “Ingolf”, “Thor” and other Danish expeditions around the end of the nineteenth century 

sampled the seabed in the north Atlantic around the Faeroes, Iceland and Greenland, 

recording 66 species, 24 of which were new to science (Hansen, 1920). 

The Voyages of Prince Albert I of Monaco took place between 1886 and 1912 in the Bay of 

Biscay, off Portugal and near the Azores. Forty species of cumaceans were identified, of 

which seven were new (Fage, 1929). The end of this era was completed some decades later 

with the Danish round-the-world voyage of the “Galathea” expedition 1950-1952, when the 

Bay of Biscay was one of the stations. Thirty species of cumaceans were identified of which 

26 species were new and one was referred to a new genus (Jones, 1969). From this time 

onwards it was widely accepted that the deep sea was much more diverse than previously 

thought. 

More recently, to the south west of Ireland, the Institute of Oceanographic Sciences Deacon 

Laboratory (IOSDL) carried out an intensive survey of the benthic biology of the Porcupine 

Seabight between 1977 and 1986. However, the most extensive deep-sea time series 

collection was made by the Scottish Association of Marine Sciences (SAMS) starting 1973 in 

the Rockall Trough. Also a shorter time series was taken from the Anton Dohrn SeaMount 

since 1980. Primarily from SAMS‟s collection and others, Norman Jones described a large 

number of new species, mainly in the family Nannastacidae. A survey of the area around the 

Faroe Islands (BIOFAR programme) was carried out between 1987 and 1990 (see Norrevang 

et al 1994 for station data). The result of that produced 62 cumacean species, of which 42 are 

additional species to the listed 28 species by Hansen (1920) and Stephensen (1929). One of 

the 42 additional species is a new leuconid described by Watling and Gerken (1999). That 

increases the Faroe cumacean list to 70 species by Gerken and Watling (1999). The Benthic 

Invertebrates of Icelandic waters (BIOICE) Programme commenced in 1992 and sampling 

continued until 1997. Its main objective was to revise the systematics of the marine 

invertebrates of the area. More than 1000 samples were collected around Iceland from 20m 

down to 2400m depth. All the cumacean information relating to the BIOICE programme 

remains unpublished. 

In 1996, 20,000 square kilometres of seabed lying to the west of the Shetland which was 

licensed for oil and gas exploration before or during 1996, was mapped and sampled by 

Atlantic Frontier Environmental Network (AFEN). In 1998, a further 10,000 square 

kilometres north and west of Scotland that covered the 17 th U.K. oil licensing round was 

surveyed (see Bett 1997 and 1999 for the survey area and sampling details). From both 

surveys 102 cumacean species were identified, 27 of which are of taxonomic importanceeither 

new species, or species which were poorly described and causing taxonomic problems 

(Shalla, 2001). Out of the 27 problematic species, four new species of the genus Leucon were 

described by Shalla and Bishop (2004); one new species of Atlantistylis was described, 

constituting the first record of the genus from the North Atlantic (Shalla and Bishop, 2005) 

and two new species of the genus Hemilamprops and Mesolamprops were described by 

Shalla and Bishop (2007). 

At the end of year 2000, the UK Department of Trade and Industry (DTI) conducted a survey 

in the area northwest of Scotland in the Faeroe-Shetland channel (2000 “White Zone” 

survey). Fifty-two cumacean taxa were recorded from depths of 141-1697m, 11 of which 

were of taxonomic importance-either new species, or species which were poorly described 

4

and causing taxonomic problems. In 2002, the DTI carried out another survey in the area 

north and west of Orkney and Shetland; no reports from this survey have been published. 

In 2003, a survey of the north east of the Porcupine Bank, together with other Irish and North 

Sea material, lead to the erection of the new genus Monopseudocuma by Mccarthy et al 

(2006). 

5

Morphology 

The cumacean body is divided into three distinct parts, the inflated carapace, the pereon 

(thorax) and the pleon (abdomen) (Fig. 1). 

The carapace consists of the cephalon (head) fused to at least the first three thoracic somites. 

The carapace extends both laterally and ventrally to enclose the branchial cavity. Each side of 

the carapace is produced anteriorly to form the pseudorostral lobes. Both lobes project 

forward and meet (but are not fused) to form the pseudorostrum (Fig. 1). Projecting 

anteriorly through the pseudorostrum is the siphon, which is the anterior part of the branchial 

apparatus of the first maxilliped. The siphon is usually short but can be very characteristically 

long in some species. In the genus Eudorella and Eudorellopsis, the pseudorostral lobes are 

reflexed upward with no obvious pseudorostrum but still with a siphon (Fig. 2). Below the 

pseudorostrum the anterior border is excavated to form the antennal notch or sinus which is 

defined below by the anterolateral corner, although in many species both are lacking. Behind 

the pseudorostrum on the dorsum is the bell-shaped frontal lobe from which the small ocular 

lobe projects forward, usually carrying the unpaired eyes (Fig. 1). The shape of the frontal 

lobe can vary from triangular to rounded, and the ocular lobe can vary in shape from small or 

absent to very long (Fig.2). The eye lobe normally persists (even in eyeless species), except 

when the eyes remain separated into two groups as in Nannastacus (Fig. 2). Behind and to the 

sides of the frontal lobes are the branchial regions (Fig. 1). 

The thorax (pereon) consists of five free thoracic somites (Fig. 1). Individually each is called 

a pereonite. Sometimes the first and exceptionally the second and third may be fused with 

the carapace, while the third and fourth may be fused together dorsally. 

The abdomen (pleon) consists of six cylindrical somites “pleonites” (Fig. 1). The fifth is the 

longest, while the sixth is prolonged by a freely articulated telson in five of the families. In 

the remaining three, the telson is fused with the sixth pleonite and is not distinct. The freely 

articulated telson varies in length and shape. The anus, protected by a pair of valves, opens 

on the lower face of the telson or at the end of the sixth pleonite. 

The body is covered with a chitinous epidermis, sometimes strongly calcified. Its surface is 

often sculptured with grooves, ridges, spines, tubercles or teeth, or has a fine reticulated, 

pitted or scaled appearance. It is sometimes covered with sand grains. 

The first antenna (antennule) is short (Fig. 3A). It has a peduncle of three articles and two 

flagella. The main outer flagellum is usually longer than the accessory inner flagellum, with 

two to six articles. The accessory flagellum often has only one article. One or two modified 

sensory setae ,“aesthetascs”, may be present at the end of the main flagellum. In males of 

some species (e.g. Leptostylis) a brush of sensory filaments is present on the basal articles of 

the main flagellum (Fig 3B). Between the bases of the first antenna on the underside of the 

front end of the carapace are two small chitinous plates (the epistome), to which the first 

antennae are attached (Fig. 3A). 

6

Carapace 

Pereon 

Pleon 

A B 

Pseudorostrum 

Eyelobe 

Frontal lobe 

Branchial area 

Pereonite 1 

Pereonite 5 

Pereopod 5 

Pleonite 1 

Pleonite 6 

Uropod peduncle 

Telson 

Exopod 

Endopod 

Antenna 1 

Antenna 2 

Pereopod 1 

Exopod 

Pereopod 5 

Pleopod 1 

Flagellum of Antenna 2 

Figur 1: Diastylis rathkei: A, female dorsal view; B, adult male lateral view (from Sars, 

1900). 

7

Figure 2: Examples of carapace shape and ornamentation. 

8

The second antenna (antenna) is generally rudimentary in females, with from one to five 

articles (Fig. 3A). In males, the shape and length changes at different developmental stages. 

In mature males (Fig. 3C), it is well developed with a peduncle of five articles and a manysegmented 

flagellum. The outer sides of the fourth and fifth articles of the peduncle are 

normally thickly covered with setae. The second antenna is bent backwards between the third 

and fourth articles of the peduncle, and the flagellum is closely applied to the sides of the 

body. It usually reaches to the end of the body but is sometimes shorter. In some species, the 

second antenna is used as an organ for clasping the female. The second antenna is attached to 

the upper lip (labrum) (Fig. 3A). 

The mouth parts consists the upper lip (labrum), paired mandibles, paired first and second 

maxillae and lower lip (labium) (Fig. 3A,D-H). The upper and lower lips are of no taxonomic 

significance. 

The mandibles (Fig. 3D&E) are simple and always without a palp. Each is normally 

boat-shaped, pointed at either end, with a strong molar process and toothed incisor process 

and in between them a row of setae and a distal lacinia mobilis (Fig.3D). In some families the 

mandibule is reduced to a truncate shape (Fig.3E). In Nannastacidae the mandible is 

modified to aid the predatory feeding habit, with a styliform molar process. 

The first maxillae (maxillulae) (Fig. 3F) lie ventral to the labium (Fig. 3H) and the second 

maxillae (Fig. 3G) ventral to the first pair. Both consist of a flattened protopodite bearing 

endites and the first pair have a backwardly directed palp, usually with one or two filaments, 

which vibrate in the respiratory chamber and cause a current of water to pass the gills. 

In cumaceans, the first three thoracic somites are covered by the carapace but only the first 

one is thought to be fused to the head. The first three pairs of thoracic appendages are 

maxillipeds and the last five are pereopods. Each has a short coxa fused with the sternite, 

followed by the basis, usually the longest article, which may carry an exopodite on its 

proximal part, normally with a peduncle and setiferous flagellum but sometimes a rudiment. 

Exopods are never present on the first and second maxilliped nor on the fifth pereopods, and 

the number on the other appendages varies with the species. In the female oostegites are 

borne on the coxae of the third maxilliped and the first three pairs of pereopods, lamellar in 

form and interlocking to form the brood chamber. The remaining articles are the ischium, 

merus, carpus, propodus and dactyl. 

The first maxillipeds are short, robust and highly developed (Fig.3I). The coxa carries a large 

epipod (the branchial apparatus). The anterior part of the epipod extends forward and, 

together with its counterpart, forms the siphon. Its posterior part forms finger-like branchial 

lobules (gills), often more numerous in the male than in the female. Water leaves the 

branchial chamber through the siphon. 

The second maxillipeds (Fig. 3J) usually have a long basis. The propodus and dactyl are bent 

in towards one another and may be modified, with large flattened spines. In the female there 

is a flattened plate attached to the hind end of the coxa, the rudimentary oostegite, which has 

a fringe of long slender setae directed backwards into the brood chamber. 

The third maxillipeds (Fig. 3K) are large, and partly cover the first and second pairs and the 

mouthparts. They are sometimes similar in structure to the first pereopods but usually differ 

considerably. Long feathered setae are present on the basis, acting as a screen to filter the 

9

water entering the branchial chamber. 

B 

K 

E 

A 

G 

D 

H 

epistome 

Labrum 

C 

F 

siphon 

I 

Branchial 

apparatus 

Figure 3: Detailed view of the head appendages, anterior thoracic appendages and pleopods. A, Antenna 

1 and 2 of female diastylid; B, antenna 2 of male Leptostylis; C, antenna 2 of male diastylid; D, 

mandible of diastylid; E, mandible of Campylaspis; F-G, maxilla 1 and 2 of Diastylid; H, Labium of 

diastylid; I-K; maxillipeds 1-3 of diastylid (all from Sars, 1900). 

J 

10 

coxa 

oostegites

The first two pairs of pereopods (Fig. 4) are directed forwards, the first normally reaching 

beyond the tip of the pseudorostrum. The second are usually shorter than the first and their 

ischia are often fused with the bases. The last three pairs of pereopods are directed 

backwards (Fig.4) and are used for burrowing. 

Pleopods (Fig. 4) have been reported in the female of only a single species. In the male there 

may be one, two, three or five pairs, placed at the hind ends of the pleon sternites, or they 

may be absent. The peduncle consists of a short coxa and a long basis, with two short rami, 

the outer usually with two articles and the inner with one article, normally carrying long 

plumose setae in the adult. The inner ramus is rudimentary in some species. 

The uropods are the last pair of abdominal appendages. Each consists of a uniarticulate 

peduncle and two rami, the outer ramus (exopod) with two articles and the inner ramus 

(endopod) with one to three articles (Fig. 4). Spines and setae are usually present on the 

edges of the peduncle and rami. The uropods are used as cleaning organs. 

11

carpus 

exopod 

propodus 

merus 

dactyl 

ischium 

basis 

Pereopod 1 Pereopod 2 Pereopod 3 

Pereopod 4 

Pleopod 1 

Pleopods 

Pleopod 2 

Exopod 

Uropod 

Figure 4: Thoracic and abdominal appendages: pleopods (top to bottom) of Pseudocumatidae, 

Diastylidae and Bodotriidae (from Sars, 1900); pereopods and uropods of Leuconidae (from 

Shalla and Bishop, 2003). 

Endopod 

12

Sexual dimorphism 

There is always some sexual dimorphism in adults, more pronounced in some families than 

in others, but almost always including: better development of the second antenna in the 

male; the presence of oostegites (brood pouch) in the female; the presence of pleopods 

(except in Nannastacidae) in the male; the presence of more or better-developed exopods on 

the thoracic appendages in the male, and sometimes differences in shape and ornamentation 

of the carapace, as well as differences in the development of some sense organs. 

General distinction between sexes in adult cumaceans: 

Female Male 

Antenna 2 Rudimentary Well developed, with long 

flagellum 

Oostegites or brood pouch Present Absent 

Pleopods No Yes (except in Nannastacidae) 

Exopods on thoracic 

appendages 

A2 of ♂ Leucon jonesi 

(from Bishop 1981) 

Less developed More developed (except 

Bodotriidae) 

13

Biology 

Cumaceans brood their eggs after fertilization in the brood pouch in which the embryos are 

retained and moult into a stage closely resembling the adult (manca) but lacking the last pair 

of pereopods, the secondary sexual characters, and some of the spines and setae. Several 

moults follow the manca before the adult stage is reached. The number of moults, the life 

cycle and the life span of a cumacean varies with species and environmental conditions (for 

detailed studies, see Forsman (1938), Kruger (1940), Zimmer (1941), Corey (1969, 1976, 

1983), Bishop (1982), Duncan (1984), Persson (1989), Roccatagliata (1991), Bishop and 

Shalla (1994) and Corbera et al. (2000). 

The key adopts the terminology of Bishop (1982) who summarised the developmental stages 

from a newly hatched manca to an adult in both sexes in the deep-sea species Leucon jonesi 

as follows: 

Manca: without pereopod 5 and without pleopods. 

Juvenile: with five pairs of pereopods and without external sexual differentiation. 

Immature males: pleopods not developed externally but visible through the cuticle, antenna 2 

in development but unsegmented. 

Preadult males: pleopods with peduncle and rami but no setae, antenna 2 in development and 

partially segmented with a differentiated peduncle 

Adult males: pleopods fully developed and antenna 2 flagellum fully segmented and longer 

than body length 

Immature females: without oostegites; without pleopods and antenna 2 rudimentary, as in the 

following stages. 

Preadult females: oostegites in development but not yet forming a brooding pouch. 

Brooding females: fully developed oostegites forming a marsupium containing individuals in 

different developmental stages. 

The majority of species occur in soft deposits and a number in sand where they may show a 

preference for a certain range of grain size (Foxon, 1936; Pike and Le Sueur, 1958), possibly 

related to the mesh size of their branchial filtering apparatus or the size of grain which they 

can manipulate during feeding. They normally burrow into the deposit by means of the last 

four pairs of pereopods, remaining at rest usually with only the front part of the carapace 

emerging and sometimes also the uropods, but they make fairly frequent swimming 

excursions and the adult males of many coastal species may swim up into the plankton, 

especially at night, and may rise almost to the surface to form swarms. They may be joined 

by smaller numbers of females but it is likely that females do not rise as far from the bottom 

nor remain above it for as long a time. The function of this behaviour is presumably to enable 

mating to take place, or at least for the males to find the females (from Jones, 1976). 

Cumaceans feed on micro-organisms and organic matter from the bottom deposit. Mud-living 

species filter small particles and those inhabiting sand clean their food off sand grains. In the 

latter case objects carrying food are picked up by the first pereopods and passed on to the 

third maxilliped. The food is then cleaned off by the first and second maxillipeds and passed 

on to the first and second maxillae and mandibles (Dixon, 1944). The food-manipulating 

appendages and mouthparts are suitably armed with spines and bristles. In the filter feeders 

14

the first and second maxillae together form a pump by means of which water is drawn 

through their setules which filter off particles of food (Dennell, 1934). In Campylaspis and 

some related genera the mandibles and second maxilliped are modified as piercing organs 

and they probably feed on foraminiferans and perhaps small crustaceans (from Jones, 1976). 

15

Family Bodotriidae 

Subfamily Vaunthompsoniinae 

Subfamily Bodotriinae 

Family Leuconidae 

Family Nannastacidae 

Family Pseudocumatidae 

Family Lampropidae 

Family Diastylidae 

Family Gynodiastylidae* 

Family Ceratocumatidae† 

Classification 

Although Cumaceans are a very recognizable group, their family distinctions are not as 

obvious. Various taxonomists have divided the order into 4-26 families, of which eight are 

currently accepted. The family definitions overlap to such an extent that the most difficult 

task in identification of a species is placement into a family (Day, 1980). A large part of the 

problem is due to the significant sexual dimorphism in cumaceans. Thus it is helpful to 

identify the sex and the stage of maturity of the specimen before using the key (see section on 

biology); but this is not always obvious and can mainly be learnt by experience. 

*Species are present predominantly in the southern hemisphere 

†British records from mainly deep-water 

Useful web links: 

http://www.marinespecies.org/cumacea 

http://peracarida.usm.edu/CumaceaTaxa.pdf 

Key to the Families (Fig. 5)/subfamilies* 

(*Applicable to the British species only) 

1- With freely articulated telson 2 

Without freely articulated telson 5 

2- Telson small or large, with 0 or 2 terminal spines 3 

Telson mostly well developed, always with 3 or more terminal spines Lampropidae 

3-Telson small, without apical spines. Endopod of uropod with only one article 4 

Telson larger, with 2 apical spines. Endopod of uropod with 2 or 3 articles 

Diastylidae 

16

4- ♂ with 3, 4 or 5 pairs of pleopods, pleopods with two rami 

Ceratocumatidae† 

♂ with 1 or 2 pairs of rudimentary pleopods, pleopods with one ramus (Figure 4) 

Pseudocumatidae 

5- In both sexes the last four pairs of pereopods either without exopods or with very small 

rudimentary exopods. ♂ with 5 pairs of pleopods 

Bodotriidae- Bodotriinae 

In the female at most the last three pairs of pereopods without exopods, in the male only the 

last pair. ♂ with 0, 2 or 5 pairs of pleopods 6 

6- Uropodal endopod uniarticulate. In ♀ the last three pairs of pereopods without exopods, in 

♂ only the last pair. ♂ without pleopods Nannastacidae 

Uropodal endopod with two articles. In ♀ the last two pairs of pereopods without exopods, in 

♂ the last pair. ♂ with 5 or 2 pairs of pleopods 7 

7- Eyes distinct. ♂ with 5 pairs of pleopods. In ♀ exopods of pereopods 1 well developed, of 

pereopods 2-3 well developed or rudimentary. Mandible of normal shape 

Bodotriidae-Vaunthompsoniae 

Eyes wanting. ♂ with 2 pairs of pleopods. In ♀ exopods of pereopods 1-3 well developed. 

Mandibles truncate at base Leuconidae 

*Key modified from Jones (1976) and Watling and McCann (1997) 

†British records are mainly deep-water, not discussed in the following key. 

17

Figure 5: Representative cumaceans from the families included in the present key. 

Diastylidae ♀ 

Lampropidae ♀ 

Pseudocumatidae 

Bodotriidae ♀ 

Bodotriidae ♂ 

Nannastacidae ♀ 

Leuconidae ♀ 

18

Family DIASTYLIDAE 

Diagnosis (as emended by Day, 1980 and Watling and McCann, 1997): Mandibles normally 

boat-shaped but widened at base in Diastyloides. First maxilliped branchial filament with 

numerous leaflets. Exopods present on maxilliped 3 (except in Paradiastylis) and in females 

on pereopods 1 and 2, absent or rudimentary on pereopods 3 and 4, in males present on 

pereopods 1-4. Telson variable, usually large, often with a long post-anal part, or short and 

poorly armed; bearing one pair of terminal spines or none. Uropods usually long and slender, 

endopod with 3 articles. Male antenna 2 with long flagellum reaching at least to the posterior 

end of thorax. Males with two pairs of pleopods (except in Atlantistylis which has no 

pleopods); no outer process on inner ramus. 

Remarks: The Diastylidae is one of the oldest and biggest cumacean families, and is well 

represented in the temperate North Atlantic. The family contains around 285 species in 20 

genera, with very clear sexual dimorphism. Identification of male specimens is very difficult 

especially if the specimen is not at the adult stage, the present key still need to improve on it. 

Jones (1976) listed 12 species in 4 genera from depths down to 200m, while the present key 

extends the depth range into the lower slopes down to 500m and contains 20 species in 5 

genera. 

Diastyloides biplicatus (G.O. Sars, 1865) 

Diastyloides serratus (G.O. Sars, 1865) 

Diastylis boecki Zimmer, 1930 

Diastylis bradyi Norman, 1879 

Diastylis cornuta (Boeck, 1864) 

Diastylis echinata Bate, 1865 

Diastylis glabra Zimmer, 1900 

Diastylis goodsiri (Bell, 1855) 

Diastylis laevis Norman, 1869 

Diastylis lucifera (Krøyer, 1837) 

Diastylis rathkei (Krøyer, 1841) 

Diastylis rugosa Sars, 1865 

Diastylis tumida (Liljeborg, 1855) 

Brachydiastylis resima (Krøyer, 1846) 

Leptostylis ampullacea (Liljeborg, 1855) 

Leptostylis longimana (Sars, 1865) 

Leptostylis macrura Sars, 1870 

Leptostylis villosa Sars, 1869 

Makrokylindrus (Adiastylis) josephinae (Sars, 1871) 

Makrokylindrus (Adiastylis) longipes (Sars, 1871) 

19

Key to the British Species of Diastylidae* 

1- Mandibles broad at base, basis of pereopod 2 usually abruptly wider than ischium with 

one or two large strong teeth at lower distal corner (Diastyloides) 2 

Mandibles narrow at base, basis of pereopod 2 narrow distally or abruptly wider than ischium 

but without one or two large strong teeth at lower distal corner 3 

2- Carapace with diagonal folds, telson (excluding spines) more than half as long as the 

peduncle of the uropod Diastyloides biplicata 

Carapace without diagonal folds, telson (excluding spines) about half as long as the peduncle 

of the uropod Diastyloides serrata 

3-Telson short, shorter than the last abdominal somite (Leptostylis) 4 

Telson long, longer than the last abdominal somite 7 

4- Lower front edges of carapace with flat-topped teeth Leptostylis villosa 

20

Lower front edges of carapace with triangular teeth 5 

5- Pereopod 1 with the basis little longer than the carpus 

Leptostylis longimana 

Pereopod 1 with the basis much longer than the carpus 6 

6- Pereopod 1with the basis as long as the carpus, propodus and dactylus combined, peduncle 

of the uropod not much longer than its endopod 

Leptostylis ampullacea 

Pereopod 1with the basis much shorter than the carpus, propodus and dactylus combined, 

peduncle of the uropod much longer than its endopod 

Leptostylis macrura 

Pereopod 1of : 

L. macrura L. ampullace L. longimana 

Uropod of: 

7- Post-anal part of telson shorter than pre-anal part 

(Makrokylindrus) 8 

Post-anal part of telson longer than or equal to pre-anal part 9 

8- Post-anal part of the telson with at most one pair of lateral spines 

Makrokylindrus josephinae 

Post-anal part of the telson with at least three pairs of lateral spines 

Makrokylindrus longipes 

L. macrura L. ampullacea 

21

9- Pseudorostrum of ♀ strongly upturned, of ♂ slightly upturned, pereopods 2 and 3 widely 

separated in ♀and to a lesser extent in ♂ Brachydiastylis resima 

Pseudorostrum not strongly upturned, pereopods 2 and 3 not widely separated 

(Diastylis) 10 

10- Pleopods absent or ,when present, without feathered setae (♀♀ and immature ♂♂) 

11 

Pleopods present and with long feathered setae (adult ♂♂) 20 

11- Carapace with 3-5 vertical folds extends to the posterior half of the carapace and two 

pairs of strong dorsal spines 

Diastylis rugosa 

Carapace without distinct folds or with 1-2 indistinct folds in the anterior part of the carapace 

12 

12- Carapace with a number of large teeth 13 

Only small teeth or none on the carapace 14 

13- Read three alternatives 

One very prominent pair of teeth and c14 smaller ones on the carapace Diastylis cornuta 

One prominent pair of teeth and fewer c6 smaller ones on the carapace Diastylis boecki 

Prominent pair of teeth absent. Carapace divided into polygonal areas by numerous teeth, 

spines and spinules Diastylis echinata 

14- Carapace thickly covered with hairs Diastylis goodsiri 

Carapace not thickly covered with hairs 15 

D. cornuta D. boecki D. echinata 

22

15. The pre-anal part of the telson about as long as the post-anal part Diastylis tumida 

The pre-anal part of the telson distinctly shorter than the post-anal part 16 

16- Telson with no more than 4 lateral spines on either side Diastylis lucifera 

♀ 

Telson with at least 6 lateral spines on either side 17 

17- Two long rows of small teeth on the frontal lobe 18 

Where there are teeth on the frontal lobe they are arranged transversely 19 

18- Carapace less than one and half as long as broad Diastylis glabra 

Carapace more than one and half times as long as broad Diastylis rathkei 

propod 

us 

Diastylis glabra 

Diastylis rathkei 

19- Prolongation of the hind end of pereonite 5 ending in a short blunt point. Propodus of 

pereopod1 about twice as long as dactylus Diastylis laevis 

23

Prolongation of hind end of pereonite 5 ending in a long sharp point. Propodus of pereopod 1 

much less than twice as long as dactylus Diastylis bradyi 

Diastylis laevis 

propodus 

dactylus 

20- No lateral ridges on the carapace 21 

Lateral ridges, which may be only faintly defined, present on carapace 22 

Diastylis bradyi 

21- First article of uropod endopod shorter than the other two articles together 

Diastylis lucifera 

First article of uropod endopod longer than the other two articles together 

Diastyloides serrata 

22- No vertical or diagonal ridges nor pseudorostral ridges on the carapace 

23 

Vertical or diagonal ridges present on carapace, or where absent at least pseudorostral lines 

present 28 

23- Subrostral lines present or the lateral ridges extend to the subrostral margin of the 

carapace 24 

Subrostral lines absent, the lateral ridges not reaching to the subrostral margin of the carapace 

27 

24- No protuberances on the carapace 25 

Protuberances present on the carapace in the position where large teeth are present in the 

females 26 

25- Telson with not more than 4 lateral spines, 3 teeth on the frontal lobe 

Diastylis lucifera 

24

Telson with more than 4 lateral spines, no teeth on the frontal lobe 

Diastylis tumida 

26- 2 pairs of protuberances on the carapace Diastylis cornuta 

Only one pair of protuberances on the carapace Diastylis boecki 

27- Carapace thickly covered with hairs, length over 25mm Diastylis goodsiri 

Carapace not thickly covered with hairs, length about 8mm Diastylis lucifera 

28- The pseudorostral lines form an angle broadly open towards the underside, propodus of 

pereopod 1 about twice as long as dactylus Diastylis laevis 

The pseudorostral lines run otherwise or absent 29 

29- Pereonites 2-4 without depressions in the mid-line 30 

Pereonites 2-4 depressed in the mid-line so that two distinct but low keels are formed 

32 

30- No pseudorostral lines 31 

Pseudorostral lines present Diastylis bradyi 

31- 2-3 vertical lines on the carapace Diastylis rugosa 

Only 1 oblique line on the carapace Diastylis boecki 

32- Pseudorostrum short Diastylis rathkei 

Pseudorostrum long Diastylis glabra 

*Key modified from Jones 1957 and 1976 

25

Makrokylindrus longipes 

Immature ♂ 

Makrokylindrus josephinae ♀ 

Diastylis echinata 

Brooding ♀ 

Diastylis cornuta 

Brooding ♀ 

26

Family: LAMPROPIDAE 

Diagnosis (Day, 1978, Watling and McCann, 1997): Antenna 1 with well developed 

flagellum. Mandibles boat-shaped. Maxilla 1 palp absent or bearing 1 or 2 setae. Exopods 

present on maxillipeds 3 and pereopod 1 in both sexes; in female present or rudimentary on 

pereopods 2-4 or absent from all three; in male exopods present on pereopods 2-4. Pleopods 

absent or 1-3 pairs in male, with outer process on inner ramus. Telson moderate to large, well 

developed post-anally, with 3-8 terminal and subterminal spines. 

Remarks: The family Lampropidae is clearly distinguished by the presence of at least 3 

terminal spines on the telson. The family contains around 100 species in 14 genera and is 

well represented in the North Atlantic. Of these, Chalarostylis Norman, 1879, Lamprops 

Sars, 1863, Hemilamprops Sars, 1883, Mesolamprops Given, 1964, Paralamprops Sars, 

1887, and Platysympus Stebbing, 1912 are discussed here. The genus Chalarostylis is defined 

by a short telson, a robust first pereopod with a group of long setae on the dactylus, and 3 

pairs of pleopods in males. The genera Lamprops, Hemilamprops and Mesolamprops are 

very similar; males are readily separated by the absence of pleopods in Lamprops versus the 

presence of three and two pairs of pleopods in Hemilamprops and Mesolamprops 

respectively. Ascribing females to genus without reference to the corresponding males is 

more problematic but, as noted by Haye & Gerken (2005), Hemilamprops and Mesolamprops 

both have the basis of the first pereopod much shorter than the rest of the appendage, whereas 

in Lamprops it is equal in length to the rest of the appendage. The genus Platysympus is well 

defined by the strongly flattened carapace with a pronounced marginal carina, the absence of 

exopods on pereopods 2 to 4 in females and the presence of 3 pairs of pleopods in males. The 

genus Paralamprops is defined by a broad depressed carapace, with a marginal carina, 

exopods on pereopods 3 to 4 rudimentary or absent in females and the presence of 3 pairs of 

pleopods in males. Jones (1976) listed 2 species in 2 genera from depths down to 200m, 

while the present key extends the depth range to the lower slopes down to 500m and contains 

13 species in 6 genera. 

Chalarostylis elegans Norman, 1879 

Hemilamprops assimilis Sars, 1883 

Hemilamprops cristatus (G.O. Sars, 1870) 

Hemilamprops normani Bonnier, 1896 

Hemilamprops pellucidus Zimmer, 1908 

Hemilamprops pterini Shalla and Bishop, 2007 Atlantic 

Hemilamprops roseus (Norman, 1863) 

Hemilamprops uniplicatus (G.O. Sars, 1872) 

Mesolamprops denticulatus, Ledoyer, 1983 

Mesolamprops hartleyi Shalla and Bishop, 2007 

Paralamprops orbicularis (Calman, 1905) 

Platysympus typicus (Sars, 1870) 

Lamprops fasciata Sars, 1863 

27

Key to the British Species of Lampropidae 

1- Telson small, sub equal in length to pleonite 6 and less than half the length of the peduncle 

of the uropod Chalarostylis elegans 

From Gerken and McCarthy (2007) 

Telson long, longer than pleonite 6 and more than half the length of the peduncle of the 

uropod 2 

2- Basis of pereopod 4 longer than entire length of pereopod 5. Males with 3 pairs of 

pleopods Paralamprops orbicularis 

Basis of pereopod 4 subequal to, or shorter than, entire length of pereopod 5. Males with 0, 2 

or 3 pairs of pleopods 3 

3- Carapace strongly flattened with a pronounced marginal carina . Males with 3 pairs of 

pleopods Platysympus typicus 

Carapace not as above. Males with 0, 2 or 3 pairs of pleopods 4 

4- Read three alternatives 

Male without pleopods, antennal notch small but distinct, eyes present. Basis of pereopod 1 

approximately equal in length to the rest of the appendage. Telson with 5 apical spines, the 

median being the longest. Carapace with 3 oblique folds Lamprops fasciata 

Male with 2 pairs of pleopods, antennal notch present or absent, eyes present or absent. Basis 

of pereopod 1 shorter than the rest of the appendage, carapace without oblique folds 

(Mesolamprops) 5 

Male with 3 pairs of pleopods, antennal notch usually absent, eyes present or absent. Basis of 

pereopod 1 distinctly shorter than the rest of the appendage, carapace with or without oblique 

folds (Hemilamprops ) 6 

28

5- Dorsal crest denticulate in the anterior half of carapace including eye lobe. Telson slightly 

over half but less than three-quarters the length of uropodal peduncle 

Mesolamprops denticulatus 

Dorsal crest, including the eye lobe smooth, telson slightly over three-quarters the length of 

uropodal peduncle Mesolamprops hartleyi 

6- Carapace with no lateral folds, telson with three or more apical stout setae 7 

Carapace with lateral folds, telson with three apical stout setae 10 

29

7- Dorsal crest smooth 8 

Dorsal crest serrated 9 

8- Telson with eight apical and two pairs of lateral stout setae 

Hemilamprops roseus 

Telson with six apical and one pair of lateral stout setae 

Hemilamprops assimilis 

9- Telson with five apical and six pairs of lateral stout setae 

Hemilamprops normani 

Telson with three apical and seven pairs of lateral stout setae 

Hemilamprops pellucidus 

Telson with three apical and two to three pairs of lateral stout setae 

Hemilamprops cristatus 

10- Carapace with prominent lateral fold on each side; branchial region not inflated. Telson 

subequal in length to the peduncle of the uropod, with three apical and five to seven pairs of 

lateral stout setae Hemilamprops uniplicatus 

30

Carapace with relatively inconspicuous lateral folds; branchial region inflated on each side. 

Telson about three quarters the length of the peduncle of the uropod, with three apical and 

two to three pairs lateral stout setae 11 

11- Dorsal crest including eye lobe, antero-lateral corner of carapace and basal part of telson 

serrated Hemilamprops cristatus 

Hemilamprops cristatus ♀ 

Dorsal crest including eye lobe, antero-lateral corner of carapace and basal part of telson 

smooth Hemilamprops pterini 

31

Family PSEUDOCUMATlDAE 

Diagnosis (as emended from Jones, 1976 and McCarthy et al, 2006): Telson present but 

small. Males with one pair of pleopods or two, the second pair somewhat rudimentary. 

Pleopods monoramous. Males with exopods well developed on maxilliped 3 and pereopods 

1-4. Females with exopods well developed on maxilliped 3 and pereopods 1-2, and 

rudimentary on pereopods 3-4. The uropodal endopod with a single article. 

Remarks: Pseudocumatidae is a small family with only three genera present in British 

shallow waters. The new genus Monopseudocuma was initiated by McCarthy et al (2006) to 

accommodate Pseudocuma gilsoni which differed from the rest of the species in the genus 

Pseudocuma by the following combination: 1 pair of pleopods in the male; pereopod 1 

normal, fully developed exopods on pereopods 1-4 in males and 1-2 in females, rudimentary 

exopods on pereopods 3-4 in females. Antenna 2 in female uni-articulate. Uropods long and 

slender. Jones (1976) listed 4 species in 2 genera from depths down to 200m, while the 

present key extends the depth range to the lower slopes down to 500m but has no additions to 

Jones‟ Pseudocumatid list. 

Petalosarsia declivis (Sars, 1865) 

Monopseudocuma gilsoni (Gilson, 1906) 

Pseudocuma longicornis (Bate, 1858) 

Pseudocuma similis Sars, 1900 

32

Key to the British Species of Pseudocumatidae 

1- The first pereopod shortened and peculiarly formed with expanded flattened carpus 

Petalosarsia declivis 

♀ 

♂ 

The first pereopod not shortened, of normal shape 2 

2- With 1 or 2 pairs of pleopods, exopods well developed on maxilliped 3 and pereopods 1-4 

(males) 3 

Without pleopods, exopods well developed on maxilliped 3 and pereopods 1 and 2 but 

rudimentary on pereopods 3 and 4 (females) 5 

3- With 1 pair of pleopods. Antenna 2 flagellum extends to the end of pereon, or just beyond. 

Uropod peduncle with only one inner spine: endopod with 5-7 stout setulose setae and very 

fine setae in between Monopseudocuma gilsoni ♂ 

With 2 pairs of pleopods. Antenna 2 flagellum long, extends to at least pleonite 5 

4 

4- Anterolateral angle of the carapace armed with 3 teeth. Uropod peduncle with 1 simple 

seta Pseudocuma similis ♂ 

33

Anterolateral angle without teeth. Uropod peduncle with 4 plumose setae 

Pseudocuma longicornis ♂ 

5- Anterolateral angle of the carapace armed with 3 teeth. Telson broader than long, truncate 

Pseudocuma similis♀ 

Anterolateral angle without teeth. Telson nearly semi- circular 6 

6- Uropod peduncle shorter than endopod. Endopod with 5-10 stout setulose setae 

Pseudocuma longicornis♀ 

Uropod peduncle equal to endopod. Endopod with 3-4 stout setulose setae 

Monopseudocuma gilsoni♀ 

34

Family BODOTRIIDAE 

Diagnosis (emended from Jones, 1976, Watling 1977 and Day, 1978): No articulate telson. 

Pleopods (males only) with a prolonged process on the outer edge of the inner ramus (Fig. 4), 

usually 5 pairs, occasionally 2 or 3 pairs. Exopods present on the third maxilliped and at least 

pereopod 1, but may occur on pereopods in the following combinations: in the male, 4 or 1, 

occasionally 2 or 3 fully developed pairs, 1 and 2 rudimentary, 2 and 2 rudimentary, or 3 and 

1 rudimentary; in the female, 3 or 1, occasionally 2 fully developed pairs, 3 and 1 

rudimentary, 2 and 2 rudimentary, 2 and 1 rudimentary, or 1 and 2 rudimentary. The 

mandibles are not broadened at the base. The number of free thoracic somites is often 

reduced. 

Remarks: The family Bodotriidae is the second most diverse after the family Nannastacidae, 

reaching its highest diversity in the South West Pacific. The family was divided into two 

subfamilies, Bodotriinae and Vaunthompsoniinae by Hall (1944) according to the number of 

exopods on the pereopods. A third subfamily, Mancocumatinae, was established by Watling 

(1977) on the same bases. The family now contains around 360 species in 33 genera. Jones 

(1976) listed 11 species in 5 genera from depths down to 200m; the present key extends the 

depth range to the lower slopes down to 500m and contains 13 species in 7 genera. The two 

additional species are Bathycuma brevirostre (Norman, 1879) recorded from the middle and 

lower slopes in the AFEN survey but at 205m west of Ireland by Calman (1905) and 

Cyclaspis longicaudata Sars, 1865 recorded from the shelf to lower slopes on both sides of 

the Atlantic. 

Subfamily: Vaunthompsoniinae 

Cumopsis goodsiri (v. Beneden, 1861) 

Cumopsis longipes (Dohrn, 1869) 

Cumopsis fagei Bacescu, 1965 

Vaunthompsonia cristata Bate, 1858 

Bathycuma brevirostre (Norman, 1879) 

Subfamily: Bodotriinae 

Bodotria arenosa Goodsir, 1843 

Bodotria pulchella (Sars, 1878) 

Bodotria scorpioides (Montagu, 1804) 

Bodotria armoricana Le Loeuff & Intes, 1977* 

Eocuma dollfusi Calman, 1907 

Iphinoe tenella Sars, 1878 

Iphinoe trispinosa (Goodsir, 1943) 

Iphinoe serrata Norman, 1967 

Cyclaspis longicaudata Sars, 1865 

* Species not in the key but to be considered. 

35

Key to the British Species of Bodotriidae 

1- Well developed or rudimentary exopods on pereopods 1-3 or 1-4 in the male and 1-3 in the 

female Vaunthompsoniinae 2 

Well developed exopods on pereopod 1 only, in both sexes 

Bodotriinae 6 

2-Telsonic somite not produced posteriorly, exopods on pereopods 2 and 3 rudimentary 

3 

Telsonic somite produced posteriorly between the uropods, exopods on pereopods 2 and 3 

well developed 5 

3- Carapace with two pairs of lateral ridges Cumopsis goodsiri 

Carapace without lateral ridges. 4 

4- Distal article of uropodal endopod with one thin apical spine and several lateral spines; 

first article of uropodal exopod shorter than the second Cumopsis longipes 

Distal article of uropodal endopod with only one stout spine at the end; first article of 

uropodal exopod longer than the second Cumopsis fagei 

5- Maxilliped 3 with distal end of basis little or not at all produced and with ischium much 

wider than long. Pseudorostral lobes not reaching beyond ocular lobe, eyes present 

Vaunthompsonia cristata 

Maxilliped 3 with distal end of basis strongly produced and with ischium as long as wide. 

Pseudorostral lobes short but reaching beyond ocular lobe, eyes absent 

Bathycuma brevirostre 

V. cristata 

B. brevirostre 

36

6- Pereon with 5 free somites, pereonite 1 visible from above 

(Iphinoe) 7 

Pereon with at most 4 free somites, pereonite 1 hidden from above 

9 

7- Pleonite 6 with 2 or 4 terminal setae. Adult males with a sternal process on pereonite 2 

8 

Pleonite 6 with 6 terminal setae. Adult males without sternal process 

Iphinoe tenella 

8- Carapace with 2-6 teeth dorsally in the female, unarmed in the male. Two terminal setae 

on pleonite 6. Antenna 1 with a single aesthetasc 

Iphinoe trispinosa 

Carapace with 8-20 teeth dorsally in either sex. Four terminal setae on pleonite 6. Antenna 1 

with two aesthetascs Iphinoe serrata 

9- Pereopod 2 with 7 articles, uropodal endopod uniarticulate with the terminal spine fused to 

the article Cyclaspis longicaudata 

37

Pereopod 2 with 6 articles (basis and ischium fused), uropodal endopod with 1 or 2 articles 

and the terminal spine fused or not fused to the article 10 

10- Carapace without lateral horns. Peduncle of the uropods much longer than the rami, 

uropodal endopod with 1 or 2 articles and the terminal spine not fused to the article 

(Bodotria) 11 

Carapace with lateral horns. Peduncle of uropods much shorter than the rami, uropodal 

endopod uniarticulate with the terminal spine fused to the article 

Eocuma dollfusi 

11- Carapace with two carinae on either side Bodotria pulchella 

♀ 

Carapace with a single carina on either side 12 

12- Uropodal endopod with two articles Bodotria scorpioides 

Uropodal endopod with one article Bodotria arenosa 

Bodotria scorpioides Bodotria arenosa 

♂ 

38

Family NANNASTAClDAE 

Diagnosis (emended from Jones, 1963 and Watling and McCann, 1997): No articulated 

telson. No pleopods. Exopods in male usually present on maxilliped 3 and pereopods 1-4, 

rarely on pereopods 1-2 or 1-3; exopods in female usually present on maxilliped 3 and 

pereopods 1-2, occasionally absent from maxilliped 3 while present on pereopods1and 2, 

rarely absent from all appendages. Mandible normal in shape or with the base widened and 

the molar process styliform. Uropod endopod uniarticulate. 

Remarks: The family Nannastacidae contains around 352 species in 19 genera and is well 

presented in the deep North Atlantic. Jones (1984) described one new genus and 41 new 

species and listed overall 99 species from depths exceeding 200m throughout the Atlantic. 

Jones (1976) listed 8 species in 3 genera from depths down to 200m. The present key extends 

the depth range to the lower slopes down to 500m and contains 17 species in 5 genera. 

Procampylaspis armata Bonnier, 1896 

Procampylaspis macronyx Hansen, 1920* 

Procampylaspis bituberculata Hansen, 1920* 

Campylaspis alba Hansen, 1920 

Campylaspis affinis Sars, 1870 

Campylaspis costata (Sars, 1865) 

Campylaspis glabra Sars, 1878 

Campylaspis globosa Hansen, 1920 

Campylaspis horrida Sars, 1870 

Campylaspis intermedia Hansen, 1920 

Campylaspis legendrei Fage, 1951 

Campylaspis macrophthalma G O Sars, 1879* 

Campylaspis rostrata Calman, 1905 

Campylaspis rubicunda (Liljeborg, 1855) 

Campylaspis sulcata G O Sars, 1870 

Campylaspis verrucosa G O Sars, 1865 

Campylaspis undata Sars, 1864 

Nannastacus brevicaudatus Calman, 1905 

Nannastacus longirostris G O Sars, 1879* 

Nannastacus unguiculatus (Bate, 1859) 

Cumella (Cumella) pygmaea G.O. Sars, 1865 

Cumella decipiens Jones, 1984* 

Cumella tarda Hansen, 1920* 

Cumella sp.aff polita? Jones, 1984* 

Styloptocuma gracillimum (Calman, 1905) 

Styloptocuma angustata Jones, 1984* 


39

Key to the British species of Nannastacidae 

1- Molar process of mandible styliform, pointed. Anterolateral angle of carapace absent or 

only slightly prominent 2 

Molar process of mandibles thick and truncate. Carapace of female with well developed 

anterolateral angle. 15 

2- Maxilla 2 with one lobe; maxilliped 2 with the dactyl shaped like a rake; pereopod 1 with 

ischium long; eyelobe extending almost to the end of the pseudorostrum 

Procampylaspis armata+ 

Maxilla 2 rudimentary, without lobes; maxilliped 2 dactyl normal; pereopod 1 with ischium 

not specially long (Campylaspis) 3 

3- Carapace smooth without tubercles, spines, ridges or lateral grooves 4 

Carapace with tubercles, spines or ridges or at least a shallow lateral groove 

6 

4- Eyelobe small and rudimentary Campylaspis alba 

Eyelobe of normal size 5 

40

5- Dactyl of pereopod 2 longer than the carpus and propodus together 

Campylaspis rubicunda 

Dactyl of pereopod 2 not longer than carpus and propodus together 

Campylaspis glabra 

C. rubicunda C. glabra 

6- Carapace with lateral furrow or ridges, but without tubercles, spines or other large 

prominences 7 

Carapace may or may not have lateral furrow, but with at least a pair of tubercles or many 

spines or large prominences, which may or may not form lateral ridges 

10 

7- Two oblique ridges arising anteriorly and extending for greater part of the length of the 

carapace on either side 8 

Three or more oblique ridges extending similarly on the carapace, posterior ridge branched 

Campylaspis costata 

8- Dactyl of pereopod 2 shorter than the carpus Campylaspis undata 

Dactyl of pereopod 2 longer than the carpus 9 

C. undata 

C. sulcata 

C. legendrei 

9- Dactyl of pereopod 2 with terminal seta. Carapace with longitudinal depressions each 

divided into two unequal parts Campylaspis legendrei 

Dactyl of pereopod 2 with no terminal seta. Carapace with depressions undivided 

Campylaspis sulcata 

41

10- Carapace with a few low dorsal protubercles 

Campylaspis affinis 

Carapace with many conspicuous tubercles 11 

11-Carapace with tuberculate ridges or with some large tubercles situated in distinct rows 

along the sides 12 

Carapace without tuberculate ridges, but low tubercles may be situated along the sides in 

rows 14 

12- Dactyl of pereopod 2 much longer than the carpus and propodus together. Pseudorostrum 

relatively long and prominent. Carapace with few large tubercles 

Campylaspis rostrata 

Dactyl of pereopod 2 at most as long as the carpus and propodus together. Pseudorostrum 

relatively short and not prominent. Carapace with many large tubercles 

13 

13- Side of carapace with three lateral ridges, the two uppermost bearing large rounded 

tubercles Campylaspis intermedia 

Side of carapace with two lateral ridges, formed of conical tubercles 

Campylaspis horrida 

14- Merus of maxilliped 3 as long as carpus and propodus together, tubercles on the carapace 

low and rounded, no depressed area on the side of the carapace 

Campylaspis verrucosa 

42

Merus of maxilliped 3 much shorter than carpus and propodus together, tubercles on the 

carapace low and rounded, depressed area on the side of the carpus present 

Campylaspis globosa 

15- Two ocular groups more or less separated (Nannastacus) 16 

A single median ocular group 17 

16- Uropods about two-thirds as long as the last two pleonites together 

Nannastacus brevicaudatus 

Uropods longer than the last two pleonites together 

Nannastacus unguiculatus 

17- Eye lobe with lenses, narrow, short, not reaching end of pseudorostral lobes 

Cumella pygmaea# 

Eye lobe without lenses, narrow, generally elongate, reaching to end of pseudorostral lobes or 

beyond Styloptocuma gracillimum* 

43

Other species not in the key but to be considered: 

+Procampylaspis macronyx Hansen, 1920 

+Procampylaspis bituberculata Hansen, 1920 

#Cumella decipiens Jones, 1984 

#Cumella tarda Hansen, 1920 

#Cumella sp.aff polita? Jones, 1984 

* Styloptocuma angustata Jones, 1984 

44

Family LEUCONIDAE 

Diagnosis (from Jones, 1976): No free telson. Pleopods without an external process on the 

inner ramus, 2 pairs, rarely 1 or 0, in male. In the male, exopods present on the third 

maxillipeds and on the first four pairs of pereopods, rarely the first two pairs; in the female 

exopods present on the first three pairs, rarely the first two pairs. The mandibles are 

broadened at the base. The endopod of the uropod with two articles or rarely uniarticulate. 

All the pereon somites are visible from above. 

Remarks: The Leuconidae is one of the earliest-recognised cumacean families, established by 

Sars (1878). Leuconidae is a very diverse family, containing 121 species in 16 genera. Jones 

(1976) listed 4 species in 3 genera from depth down to 200m. The present key extends the 

depth range to the lower slopes down to 500m with the addition of only one extra species. 

The additional species is Leucon (Crymoleucon) noerrevangi Watling and Gerken (1999), 

which was recorded from the west of Shetland at 434m deep. The family has a deep-sea 

affinity worldwide. The genus Eudorella needs revision. 

. 

Leucon (Crymoleucon) noerrevangi Watling and Gerken (1999) 

Leucon (Leucon) nasica (Krøyer, 1841) 

Leucon acutirostris G O Sars, 1864* 

Eudorellopsis deformis (Krøyer, 1846) 

Eudorella emarginata (Krøyer, 1846) 

Eudorella truncatula (Bate, 1856) 

Eudorella species A (Bate, 1856)* 


45

Key to the British Species of Leuconidae 

1- Efferent orifice anterior or anterodorsal 2 

Efferent orifice distinctly dorsal, pseudodorsal lobes directed dorsally 

3 

2- Antenna 1 accessory flagellum extending at least to midlength of main flagellum first 

article; frontal lobe with lateral group of spines; pseudorostral lobe with group of spines 

Leucon (Crymoleucon) noerrevangi 

Antenna 1 accessory flagellum clearly less than half the length of main flagellum first article; 

frontal lobe with one spine at most; pseudorostral lobe without group of spines 

3- Antenna 1 geniculate between articles 1 and 2. Uropod endopod shorter than exopod 

Eudorellopsis deformis 

Antenna 1 geniculate between articles 2 and 3. Uropod endopod longer than exopod 

4 

4- Tooth below sinus at front of carapace small, not projecting beyond upper teeth (applies 

best to ♀♀) 

Eudorella truncatula 

♀ 

From Watling and Gerken (1999) 

Tooth below sinus large, projecting beyond the upper teeth (applies best to ♀♀) 

Eudorella emarginaia 

♀ 

♂ 

46

CUMACEA - NMBAQC

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