Abstract The monotypic genus Paraschizopera Wells, 1981 (ex Diosaccidae) is transferred to the Tetragonicipitidae on the basis of segmentation of antennary exopod and P2-P4 endopods, setation of P1 and overall similarity in mouthpart structure. Paraschizopera is the most primitive genus of the family and closely related to Diagoniceps Willey, 1930 which is redefined to encompass only the laevis-group . The menaiensis-group is allocated to Paraschizopera which includes now P. beckeri Wells (type-species), P menaiensis (Geddes) and P. trifida (Yeatman). The new name D. brevicauda is proposed for Diagoniceps sp . sens

Rony Huys

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Hydrobiologia 308: 2 3-28, 1995 .
© 1995 Kluwer Academic Publishers. Printed in Belgium.
Some remarks on the taxonomic status of Paraschizopera Wells, 1981
(Copepoda: Harpacticoida)
Rony Huys
Zoology Department, The Natural History Museum, Cromwell Road, London SW7 5BD, England
Received 23 March 1994 ; in revised form 13 July 1994 ; accepted 18 August 1994
Key words: Paraschizopera, Diagoniceps, Tetragonicipitidae, generic key, systematics
Abstract
The monotypic genus Paraschizopera Wells, 1981 (ex Diosaccidae) is transferred to the Tetragonicipitidae on the
basis of segmentation of antennary exopod and P2-P4 endopods, setation of P1 and overall similarity in mouthpart
structure. Paraschizopera is the most primitive genus of the family and closely related to Diagoniceps Willey,
1930 which is redefined to encompass only the laevis-group . The menaiensis-group is allocated to Paraschizopera
which includes now P. beckeri Wells (type-species), P menaiensis (Geddes) and P. trifida (Yeatman). The new
name D. brevicauda is proposed for Diagoniceps sp . sensu Bodin (1979). Keys are provided to the species of
Paraschizopera and Diagoniceps, and to the genera of the Tetragonicipitidae .
23
Introduction
In 1979 Becker & Schriever described a juvenile
harpacticoid taken at 920 m depth in the Peru Trench
for which they proposed the name Paraschizopera
sp. This new generic name was first used by Beck-
er (1972) in his Ph . D. dissertation when he described
and illustrated a copepodid V stage under the name
'Paraschizopera Diosaccidae gen . e t sp. nov.' . Becker
& Schriever (1979) hesitated in formally validating the
new generic name on the wrong assumption that the
International Code of Zoological Nomenclature does
not permit names to be based on juvenile stages . Prob-
ably for the same reason they declined to give a trivial
name. According to Article 17(2) (ICZN, 3rd edn .) the
International Code of Zoological Nomenclature does
not exclude names proposed for one stage in the life
history . However, since the generic name Paraschiz-
opera was published in the absence of an associat-
ed nominal species name, the principle of Binominal
Nomenclature (Art. 5a) was not consistently applied .
Consequently, Paraschizopera does not satisfy the cri-
terion of availability for generic names published after
1930 since its publication was not accompanied by the
fixation of a type species (Art . 13(b)) .
In order to maintain stability in the nomenclature,
Wells (1981) formally proposed Becker & Schriever's
immature specimen as the holotype of a new species
Paraschizopera beckeri Wells, 1981, which in itself
constitutes the type species (by monotypy) of the new
genus Paraschizopera Wells, 1981 . Paraschizopera
Becker & Schriever, 1979 is an unavailable name
which cannot enter into the synonymy of Paraschiz-
opera Wells, 1981 .
Relationships
Becker & Schriever (1979) placed Paraschizopera in
the Diosaccidae but did not present any supporting
evidence for this. In the discussion on relationships
they identified a 'Verwandtschaftsgruppe' comprising
Paraschizopera, Schizopera Sars and Schizoperoides
Por, the latter probably being the closest relative of
the new genus . Becker & Schriever claimed this rela-
tionship on the basis of the trisetose, one-segmented
antennary exopod, the presence of only 2 outer spines
on the distal exopod segment of P1-P4 and the ten-
dency towards reduction in the number of endopo-
dal segments of P2-P4 . Conversely, they postulated
that both genera could not possible have been derived
24
from one another because Schizoperoides retains the
3-segmented condition in the endopod of P2-P3 and
Paraschizopera displays the plesiomorphic character
states (Becker, 1972) for the mandibular exopod (2-
segmented) and the proximal exopod segment of P2-P4
(inner seta present) . Recently, Mielke (1992) also con-
sidered Paraschizopera in his phylogenetic scheme on
the relationships of Schizopera, Eoschizopera Wells
& Rao and Schizoperopsis Apostolov but excluded
Schizoperoides from his analysis . Based on the pres-
ence of 2 outer spines on the distal exopod segment of
P2-P4, Mielke regarded Paraschizopera as the hypo-
thetical outgroup of the 'Schizopera complex' in which
both Eoschizopera and Schizoperopsis represent para-
phyletic groupings. Surprisingly, only the former was
formally relegated to a junior subjective synonym of
Schizopera .
Neither phylogenetic scenario is convincing . In
both, it is the reduced number of exopodal spines on
P2-P4 that represents the only key character, howev-
er its usefulness is limited since it is known to have
arisen convergently in the Diosaccidae (Mielke, 1992) .
An alternative scenario is that Paraschizopera is not
a diosaccid. Becker & Schriever (1979) stressed the
atypical diosaccid characters such as the 2-segmented
condition of the P2-P4 endopods, a character found
only in Pseudostenhelia Wells, Onychostenhelia Ito
and some species of Pseudomesochra T. Scott. The
presence of 2-segmented P2-P4 endopods (occasional-
ly reduced to a 1-segmented condition in e .g . Oniscop-
sis Chappuis) is a diagnostic family characteristic for
the Tetragonicipitidae . Similarly, the caudal ramus of
Paraschizopera has a very distinctive shape, and with-
in the Diosaccidae is only remotely reminiscent of the
condition in some species of Schizopera and Schizoper-
oides (Becker & Schriever, 1979) . Caudal rami are
sexually dimorphic in the majority of the Tetragonicip-
itidae with the female condition frequently resembling
the shape in Paraschizopera . The 1-segmented anten-
nary exopod is another unusual diosaccid character,
however, this condition and the precise arrangement of
the 3 exopodal setae (1 lateral, 1 subapical, 1 apical) is
found in the majority of the Tetragonicipitidae (in some
species the exopod can be further reduced to a bise-
tose or unisetose knob) . The mouthparts of Paraschiz-
opera agree in all aspects with a typical tetragonicipi-
tid . Finally, the setation pattern of the 3-segmented P1
exopod, lacking inner setae on proximal and middle
segments and 4 setae present on the distal segment is
a standard feature for the Tetragonicipitidae, the only
exception being Oniscopsis where the exopod became
secondarily 2-segmented .
The unmodified fifth leg (as opposed to the foli-
aceous P5 of e.g. Phyllopodopsyllus T. Scott) relates
Paraschizopera to Tetragoniceps Brady and Diagoni-
ceps Willey. Conversely, the 3-segmented P1 endopod
of P. beckeri links it to the genera Pteropsyllus T. Scott
and some species of Diagoniceps . The only two tetrag-
onicipitids that exhibit the combination of these two
characters are Diagoniceps menaiensis Geddes and D .
trifida Yeatman . D. menaiensis has remained an enig-
ma since its description (Geddes, 1968) . Its inclusion
in the genus has been questioned by several work-
ers (Geddes, 1968 ; Coull, 1973; Bodin, 1979) mainly
because of the 3-segmented PI endopod. The discov-
ery of D. trifida led Yeatman (1980) to conclude that
both species could not be justifiably separated from the
genus Diagoniceps . Yeatman (1980) however, over-
looked Marinov's (1974) description of D. kunzi Mari-
nov, and for some obscure reason did not include D.
monodi Chappuis & Kunz or D. bocki Lang in his
discussion . Kunz (1984) made an overall comparison
including all species and established two groups with-
in Diagoniceps . The laevis-group contains all species
with a 2-segmented Pl endopod : the type-species D.
laevis Willey, D. bocki, D. monodi and D. kunzi . The
menaiensis-group includes D. menaiensis and D. trifi-
da, and is defined by the 3-segmented PI endopod and
the absence of the inner seta on P2 exp-2 . Despite being
based on a subadult, it is clear that P. beckeri belongs
to the menaiensis-group . Becker & Schriever (1979)
and Wells (1981) identified the immature specimen as
a copepodid V female but comparison of the fifth leg
setation pattern with Bodin's (1979) redescription of
D. menaiensis suggests that it is a CV male .
The menaiensis-group shows also a number of oth-
er distinctive characters such as the sexual dimorphism
in the rostrum, the absence of inner setae on the mid-
dle exopod segment of P2 and the presence of a mod-
ified, swollen spine anterior to the geniculation in the
male antennule. On the basis of this suite of characters
the menaiensis-group is formally synonymized with
the genus Paraschizopera. It is unfortunate that the
type-species is based on a copepodid only, particularly
when detailed descriptions are available for both sexes
of P menaiensis (Geddes, 1968; Bodin, 1979) . Bodin
(1979) listed some differences between his specimens
and Geddes' types but considered these as insufficient
to warrant the establishment of a new species . Whereas
most of these discrepancies can be attributed to defi-
ciencies in the original description, one major differ-
ence illustrated by Bodin but not included in the dis-
cussion is the different shape and setation of the female
P2 endopod. In the females of Anglesey (Fig . IA) the
distal endopod segment is distinctly longer than the
proximal and bears 1 spine and 2 long setae. In Bod-
in's illustration this segment is slightly shorter than
the proximal and possesses two juxtaposed smooth
setae apically . This is exactly the condition as found in
the Anglesey males (Fig. 1B), except that the minute
inner seta (arrowed in Fig . 1B) was overlooked, and
therefore Bodin must have unintentionally illustrated
a male specimen . Bodin also illustrated an extra seta
on the distal segment of the male P4 endopod . Re-
examination of the types of P menaiensis (BNMH reg .
nos. 1967.8 .1 .1-2) failed to discern this seta . Instead,
a secretory pore was found in an almost identical posi-
tion (Fig. 1D), suggesting that the additional seta in the
French specimens might well be a tubular extension of
the pore. Inspection of the type material also revealed
that the male P5 exopod is 2-segmented (Fig . IE) . It is
interesting to note that this segment boundary has also
been reported in some males of Tetragoniceps (Por,
1965), and in combination with the 3-segmented PI
endopod and the unmodified P5 reinforces the very
primitive position of Paraschizopera .
P menaiensis and P trifida can be easily differen-
tiated by the different swimming leg setal formula and
caudal ramus shape . The only substantial difference
between P. beckeri and P. trifida is the presence of an
extra seta on P4 exp-3 in the latter, however, it is possi-
ble that this seta is only added at the final moult . Clear-
ly, we have to await the discovery of adult specimens
before we can assess the status of the type-species . P
trifida was also described from the American Pacific
seaboard (Yeatman, 1980) but from a much shallower
locality than P. beckeri .
Paraschizopera Wells, 1981
Diagnosis. Tetragonicipitidae. Rostrum sexually
dimorphic . Antennule 9-segmented in 9 ; segment 1
shorter than segment 2 ; proximal segments without
spinous processes ; haplocer in d' with 3 segments
distal to geniculation and modified swollen spine on
segment 6 . Antennary exopod with 3 discrete setae .
Mandibular exopod well developed, elongate, usual-
ly 2-segmented . Maxillule without epipodite . P1 with
with 3-segmented exopod and endopod . P2-P3 exp-
3 without inner setae . P2 exp-2 without inner seta .
Swimming leg sexual dimorphism in P2 endopod (enp-
2 reduced in size, with outer spine missing and distal
setae modified) and P3 endopod (outer spine modified) .
P5 not modified in 9 .
Gender. Feminine. Caudal rami sexually dimorphic .
Type-species. P beckeri Wells, 1981 (by mono-
typy)
Other species. P. maenaiensis (Geddes, 1968), P trifi-
da (Yeatman, 1980) .
Key to the species of Paraschizopera Wells, 1981
1 . P2-P3 exp-3 with 5 setae/spines ; P3 exp-2
without inner setae	menaiensis
Geddes, 1986 .
P2-P3 exp-3 wiht 4 setae/spines ; P3 exp-2
with inner seta	2.
2. P4 exp-3 with 6 setae/spines . . . . beckeri
Wells, 1981 .
P4 exp-3 with 7 setae/spines	trifida
Yeatman, 1980 .
The removal of the menaiensis-group to Paraschiz-
opera requires a redefinition of Diagoniceps which is
restricted herein to the laevis-group only.
Diagoniceps Willey, 1930
Diagnosis . Tetragonicipitidae. Rostrum not sexually
dimorphic . Antennule 9-segmented in 9 ; segment I
shorter than segment 2 ; proximal segments without
spinous processes ; haplocer in d with 4 segments dis-
tal to geniculation, without modified swollen spine on
segment 6 . Antennary exopod with 3 discrete setae .
Mandibular exopod well developed, elongate, usual-
ly 2-segmented . P1 with 3-segmented exopod and 2-
segmented endopod . P2-P3 exp-3 with 1-2 inner setae .
P2 exp-2 with inner seta . Swimming leg sexual dimor-
phism in P2 endopod (outer spine of enp-2 modified)
and occasionally P4 endopod (inner seta of enp-2 lost) .
P5 not modified in 9 . Caudal rami sexually dimorphic .
Type-species, D. laevis Willey, 1930 (by mono-
typy)
Bodin's (1979) excellent description of Diagoni-
ceps sp. based on two males from La Rochelle, leaves
no doubt that he was dealing with a distinct species .
Despite the unique setal formula in the exopods of P2-
P4 and the very short caudal rami, Bodin refrained
25
0
c
Fig. 1. Paraschizopera menaiensis (Geddes, 1968) . A, P2 endopod 9 ; B, P2 endopod d' (minute seta arrowed) ; C, P3 endopod a' ; D, P4
endopod a' ; E, P5 ci' .
from establishing a new species chiefly because of the other Diagoniceps species and the very short caudal
lack of information on the female . At present, only the ramus provides an additional discriminating character.
males of D. laevis and D. bocki are described, howev- On the basis of these differences Bodin's material is
er, it is known that sexual dimorphism does not occur regarded here as representing a new species D. brevi-
in the exopods of the thoracopods . Therefore, the La
	
cauda sp . n.
Rochelle specimens can be easily separated from all
The five species contained in the genus Diagoni-
ceps can be identified by the key below . It has to
remarked that Marinov's (1974) setal formula of the P3
exopod in D. bocki contradicts Por's (1964) descrip-
tion .
Key to the species of Diagoniceps Willey,1930
1 . P2-P3 exp-3 with 6 and 7 setae/spines,
respectively ;
P2 enp-2 with 4 setae/spines	2.
P2-P3 exp-3 with 5 and 5-6 setae/spines,
respectively ;
P2 enp-2 with 3 setae/spines	4.
2. P4 exp-3 with 8 setae/spines
	
3.
P4 exp-3 with 7 setae/spines brevicauda sp.n .
3 . Caudal ramus twice as long as
anal somite	kunzi Marinov, 1974 .
Caudal ramus about as long as
anal somite	bocki Lang, 1948 .
4 . P2-P4 exp-1 without inner
seta	laevis Willey, 1930 .
P2-P4 exp-1 with inner
seta	monodi Chappuis & Kunz, 1955 .
Key to the genera of Tetragonicipitidae
Since Coull's (1973) key to the genera of the Tetrago-
nicipitidae, the genus Oniscopsis Chappuis has been
re-allocated to the family (Becker & Kunz, 1981)
after having been previously transferred to the Parame-
sochridae (Lang, 1965) and the genus Fearia Coull
has been relegated to a junior subjective synonym of
Tetragoniceps Brady (Kunz, 1984) . Por's (1986) state-
ment that Pyrocletodes Dinet is a tetragonicipitid is
considered a slip of the pen . Since Coull's (1973) revi-
sion of the family 36 species and subspecies have been
described, invalidating some of the characters used in
his key. A new key to genera is proposed below incor-
porating these changes and the present redefinition of
Diagoniceps .
27
1 . P1 exopod 2-
segmented	Oniscopsis Chappuis, 1955 .
P1 exopod 3-segmented	2.
2. Cephalothorax with paire processes backwardly
directed, spinous
	 Laophontella Thompson & A. Scott, 1903 .
Cephalothorax without paired backwardly
directed, spinous processes	3.
3. PI endopod 2-segmented 5 .
P1 endopod 3-segmented 4.
4 . First antenulary segment longest ;
P5 exopod 9 foliaceous ; P2-P4 exp-1 without inner
seta	Pteropsyllus T. Scott, 1906 .
First antennulary segment not distinctly elongate ;
P5 exopod 9 not modified; P2-P4 exp-1
with inner seta	Paraschizopera Wells, 1981 .
5 . First antennulary segment with
dentiform projection . Tetragoniceps Brady, 1878 .
First antennulary segment without
dentiform projection	6.
6. P2-P3 exp-2 with inner
seta	Diagoniceps Willey, 1930.
P2-P3 exp-2 without inner seta	7.
7 . P2-P4 exp- 1 with inner seta; P5 9 a
large foliaceous
plate	Phyllopodopsyllus T. Scott, 1906 .
P2-P4 exp-1 without inner seta; P5 9 not
modified, with separate exopod and
baseoendopod	Protogoniceps Por, 1964 .
Acknowledgements
I would like to thank Dr Geoff Boxshall for his com-
ments on the manuscript. The author is a Visiting
Research Fellow at the Zoology Institute, University
of Ghent, Belgium .
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Some remarks on the taxonomic status of Paraschizopera Wells, 1981 (Copepoda: Harpacticoida)

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Some remarks on the taxonomic status of Paraschizopera Wells, 1981 (Copepoda: Harpacticoida)

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