Cherax nucifraga, a new species of freshwater crayfish (Crustacea: Decapoda: Parastacidae) from the Northern Territory, Australia

5 Pages·1991·1.3 MB·

by  J W Short

The Beaqle. Records of the Northern Territory Museum of Arts and Sciences. 1991 8(1):115-120
CHERAX NUCIFRAGA, A NEW SPECIES OF FRESHWATER CRAYFISH
(CRUSTACEA: DECAPODA: PARASTACIDAE) FROM THE
NORTHERN TERRITORY, AUSTRALIA.
J.W. SHORT
Queensland Museum,
P.O. Box 300, South Brisbane, Qld 4101, Australia.
ABSTRACT
A new species of freshwater crayfish, Clierax nucifraga, from the Northern Territory,
Australia, is described and illustrated. The species most closely resembles C. harretti
Clark, and has affinities with the “quadricarinatus" species-group, characterised by an
uncalcified patch on the propodus of the first chelipeds in large males.
Keywords; Taxonomy, Crustacea, Parastacidae, Cherax, new species, northern
Australia.
INTRODUCTION SYSTEMATICS
The genus Cherax Erichson, is restricted to the Cherax nucifraga sp.nov.
Australian continental plate (Australia, southern (Figs 1-4)
New Guinea and islands on the continental shelf
between the two land masses). In a revision of the Type material. HOLOTYPE - male (44.6
New Guinea Parastacidae, Holthuis (1949) re¬ mm OCL), Palm Springs, near Channel Pt, North¬
corded 12 species from mainland New Guinea, ern Territory, 13°irS, I30°10.5’E, taken from
Misool I. and the Am Islands. Holthuis (1950) barramundi {Bates calcarifer) stomach, 19 March
described two additional species from New 1983, coll. Nimrod Safaris. NTM CR0()7430.
Guinea. Description. Rostrum triangular, dorsally flat¬
Riek (1969) listed a further 27 species from tened. ca. 1.8 times longer than broad, reaching
mainland Australia, the Wcssel Islands and Badu joint between penultimate and terminal seg¬
1. No new species have been described since the ments of antennular peduncle, lateral carinae
work of Riek (1969). It is interesting therefore, feebly developed, terminating shortly after be¬
that a large undescribed species should exist in ginning of postorbital carinae, left carina bearing
the Northern Territory only 100 km from Dar¬ three blunt tubercles, the first ca. halfway along
win. rostral margin, third close to tip; right rostral
The new species was noticed as I was sorting Carina armed with two blunt tubercles positioned
through unregistered crustacean collections in slightly forward of corresponding first and sec¬
the Northern Territory Museum of Arts and ond tubercles on left carina, ventrolateral mar¬
Sciences. The distinctive chelipeds and rostrum gins with long setae, acumen broken.
immediately suggested that the specimen be¬ Eyes with cornea large, globular, well
longed to an unde.scribed species. pigmented, eyestalks short and largely concealed
Abbreviations used in text: NT, Northern Ter¬ by rostrum. Antennula of typical shape.
ritory; NTM, Northern Territory Museum of Scaphocerite short, ca. 2.2 times longer than
Arts and Sciences, Darwin; OCL, orbital cara¬ broad, clearly overreaching antennular peduncle
pace length; T, thoracic stemite, T5, thoracic and rostrum, broadest point ca. halfway along
sternite five etc.
J.W. Short
FigA.Clierax niicifraga sp.iiov., holotype male. NTM CKX)7430. Scale divisions in millimetres.
Fig.2.C/tcrav imcifra^a sp.nov.. holotype male, lateral view. Scale divisions in millimetres.
length, outer margin swollen, well calcified, depth, postorbital carinae well developed, enti-
terminating in a spine, lamina more or less ingwith tubercle anteriorly, diverging posteriorly
triangular, poorly calcified and tlexible. Antennal and ending at about half cephalon lenglli;
peduncle reaching end of scaphocerite. coxocerite cephalon posterolateral margins with raised tu-
armed with strong spine anterior to the excretory berculate region; branch iostegi tes inHated, armeJ
pore, basicerite with strong lateral spine. with five large teeth along cervical groove,
Carapace punctate, orbital carapace length ca. anterolateral regions tuberculate, branchiocardiac
twice carapace breadth and 1.6 times carapace grooves distinct.
A new crayfish from the Northern Territory
Epistome slightly concave with a number of ca. 1.3 times longer than broad, uropods of
tubercles posterolaterally. Mouthparts without typical shape.
special features. Branchial formula typical for Colouration. After seven years of storage in
genus (cf. Hollhuis, 1949). with posterior fonnalin no trace of colouration remains, apart
arthrobranch of fourth leg reduced in size. from a si ight reddish tinge to one of the uncalcified
First chclipeds large, isomoiphic. reaching patches on the first chelipeds.
beyond scaphocerite by half length of carpus, Etymology. Derived from the latin, nii.\ (a
outer margin of chela strongly convex. Fingers nut) and/iw/gf) (to break), and referring to the
strongly gaping, moveable finger bearing large unusual form of the chelae, which resemble
molar tooth ca. halfway along cutting edge, nutcrackers. The specific name is to be treated as
smaller tooth proximally, separated by long setae, a feminine noun in apposition.
row of tubercles in distal half, base of moveable Distribution. Only known from Palm Springs.
finger very broad. Fi,\ed finger with two moder¬ NT. The type locality is in low lying, fioodplain
ately large teeth and number of smaller teeth in country very close to the .sea.
proximal half, outer margin with well developed Remarks. The present specimen, taken from
uncalcified patch ca. 0.7 times length of move- the stomach of a barramundi, is remarkably
able finger. Palm broad, breadth ca. 0.9 times complete and well preserved. There is evidence
mesial length, mesial margin serrated. Carpus that the cuticle of the exoskeleton has broken
ca. 0.3 chela length, armed with four large down slightly. Possibly a number of setae have
spines, two mesial spines, anterior spine directed also been lost from areas such as the dorsomesial
ventrally, posterior spine dorsally, two palm on the first chelipeds during ingestion and
anteroventral spines, one placed below the partial digestion by the fish. For this reason
condyle, second spine halfway to anterior mesial surface detail of the carapace and the distribution
spine, anteromesial region with few moderately
long .setae. Merus of typical shape, ca. half chela
length, dorsal carina anned with anteriorly di¬
rected spine followed by series of tubercles,
inner antcrodorsal margin bearing 2 or 3 tuber¬
cles, outer ventral carina with two large spines
separated by smaller spine and with number of
tubercles posteriorly, inner ventral carina bear¬
ing two large spines anteriorly followed by many
tubercles along length, outer anteroventral angle
with large spine near condyle. Ischiobasis deeply
excavated at articulation point with coxa.
Second perciopod with palm ca. equal in
length to moveable finger, carpus slightly longer
than palm, merus ca. equal to combined length of
carpus and palm. Third pereiopods missing.
Fourth right pereiopod subchelate (probably ab¬
errant). left simple (as typical for the genus),
propodus slightly more than twice length of
dactylus, carpus ca. 3/4 length of propodus,
merus ca. 1/6 longer than propodus. Fifth
pereiopods simple, propodus almost three times
longer than dactylus. carpus ca. 2/3 length of
propodus, merus slightly shorter than propodus.
Sternal keel sharp throughout length and armed
with well developed spine on T5. lateral proc¬
esses well separated medially on T7 and T8,
setose, mesial surfaces concave, without con¬
spicuous pores, T8 with a flat circular region
medially between lateral processes.
Abdomen punctate, pleurae broadly rounded, Fig.3. Chenix luicifriiga sp.nov., liolotypc male, ccplialo-
thorax, ventral view.
second pleura with large, deep concavity, telson
117
J.W. Short
Fig.4. Chercix nucifra^a sp.nov., holotype male, left cheliped, ventral view. Scale divisions in millimetres.
of setae on the chelipeds have not been empha¬ agree with the present species in having tuber¬
sised in the description. cles on the lateral rostral carinae, rather than
Cherax nucifraga is a very distinctive species spines (the situation in other species of the
of Cherax. and belongs to a species-complex "quadricarinatus" group). Although the present
characterised by an uncalcified patch on the specimen is almost twice the size of that de¬
propodus of the first chelipeds in large males and scribed by Clark (1941), there appear to be
the presence of sharp, well-developed, carpal several strong differences between the two spe¬
spines. This complex, which 1 have termed the cies which are unlikely to be related to size. The
"quadricarinatiLs" group (after the first described main differences are;
and most well known species), presently con¬ 1. The cutting edges of the fingers of the first
tains eight species, one of which is considered to chelae bear only tubercles in C. harretti and lack
consist of two subspecies, viz. - C. quadri- the large molar tooth on the moveable finger.
crinatus (von Martens, 1868), C. hairetti Clark, Cherax harretti also lacks a wide gape between
1941, C. rhynchotits Rick. 1931, and C. nucifraga the fingers.
sp. nov. from northern Australia; C. Inrentzi 2. A row of tubercles is present on the dorsal
lorentzi J. Roux. 1911, C. divergens HolthuLs, carpus of the first chelipeds in C. harretti.
1950 (characters to separate this species from C. 3. The rostrum is much narrower at the base in
qiiadricarinatiis (von Martens) need to be de¬ C. harretti and the rostral carinae appear to end
fined) and C. moniicola Holthuis, 1950, from before the stall of the postorbital carinae.
southern New Guinea; C. lorentzi aruanus J. Cherax nucifraga sp.nov. is easily separated
Roux, 1911, from the Aru Islands; and C. from C. quadricarinatus (von Martens), which
misoUcus Holthuis. 1949. from Misool 1. occurs in the same region of the Northern Terri¬
The new species is easily distinguished from tory. by the distinctive rostrum, shorter and
other members of the group by the widely gaping broader chelae, and the length of the rostral
fingers on the first chelipeds and the large molar carinae which extend a considerable distance
tooth on the moveable finger. In this regard the past the commencement of the postorbital carinae
chelae are quite unlike the grasping/cuUing claws in the latter species (hence the four obvious
typical of the genus and appear to be adapted carinae on the carapace from which the species
more for crushing or cracking food items. Per¬ derives its name).
haps the peculiar chelae have developed specifi¬ Cherax hicarinatus (Gray, 1845), a species ol
cally for predation on freshwater gastropods uncertain taxonomic status (considered synony¬
which are a favoured prey of other Cherax mous with C. interntedius Smith by Clark (1941K
species (personal observation). synonymous with C. preissii (Erichson) b)
Cherax nucifraga most closely resembles C. Holthuis (1949); and a valid .species by Riek
harretti Clark, described from Wessel Is. (1949), although he believed the type series
(Marchinbar I.), off the northeastern NT. Unfor¬ contained two specimens of C. plehejus) de¬
tunately the only known specimen of C. harretti scribed from Port Essington, NT. docs not appear
appears lost (cf. Riek 1969; Lew Ton and Poore to be closely related to the present species. Tlu’
1987). Clark’s (1941) description and figure antcromesial. angular projection on the carpus of
118
A new crayfish from ihe Northern Territory
the first chelipeds and the “three toothed at the Holthuis, L.B. 1949. Decapoda Macrura with a revi¬
top” rostrum are not typical of the “quadri- sion of the New Guinea Para.stacidae. Zoological
Results of the Dutch New Guinea Expedition
carinatus" group.
1939. No.3. Nova Guinea 5:289-328.
Holthuis, L.B. 1950. Results of the Archbold Expedi¬
ACKNOWLEDGEMENTS
tions. No. 63.The Crustacea Decapoda Macrura
collected by the Archbold New Guinea expedi¬
The Director of the Northern Territory Mu¬ tions. American Museum Novitates 1461:1-17,
seum of Arts and Sciences, Dr C. Jack-Hinton is figs 1-4.
thanked for providing accommodation, use of Lew Ton. H.M. and Poore, G.C.B. 1987. Types of
facilities and travelling expenses between Bris¬ Parastacidae (Crustacea: Decapoda) held in the
bane and Darwin. 1 am also grateful to Dr A.J. Museum of Victoria. Occasional Papers from
Bruce for his invitation to work on the crustacean the Museum of Victoria 3:21-29.
Martens, E. von. 1868. Uberblick derneuhollandischer
collection and for the loan of the present speci¬
Flusskrebse. Monatsherichte der Deutschen
men. Dr G. Webb kindly provided information
Akademie de Wissenschaften :u Berlin
on the type locality. Mr P. Davie is thanked for
1868:615-9.
his comments on Ihe manuscript. Mr J. Wright Riek, E.F. 1951. The freshwater crayfish (family
printed the photographs. Parastacidae) of Queensland. Records of the
Australian Museum 22:368-388.
REFERENCES Riek, E.F. 1969. The Australian freshwater crayfish
(Crustacea: Decapoda: Parastacidae), with de¬
Clark, E. 1941. New species of Australian freshwater scriptions of new species. Australian Journal of
and land crayfishes (family Parastacidae). Mem¬ Zoology 17:855-918.
oirs of the National Museum of Victoria 12:31- Roux. J. 1911. Nouvelle espSces de decapodes d’eau
40. douce provenant de papouasie. Notes from the
Gray, J. 1845. New species of the genus Astaciis. In: Leiden Museum 33:81-106.
E.J. Eyre, Journals of Expeditions of Discovery
into Central Australia and overland from Ad¬
elaide to Kinfi George's Sound in the Year 1840-
Accepted 8 April 1991
I. Volume I (appendix):407-411.
119