Potamalpheops darwiniensis (Crustacea: Decapoda: Alpheidae), the third Indo-West Pacific species

7 Pages·1993·3.3 MB·

by  A J Bruce

PROC. BIOL. SOC. WASH.
106(4), 1993, pp. 698-704
POTAMALPHEOPS DARWINIENSIS
(CRUSTACEA: DECAPODA: ALPHEIDAE), THE
THIRD INDO-WEST PACIFIC SPECIES
A. Bruce
J.
Abstract.—T^NO species of the "African" alpheid shrimp genus Potamal-
pheops, P. hanleyi Bruce and P. pininsulae Bruce, have been recorded from the
Indo-West Pacific region. The genus is otherwise known from fourWestAfrican
A
species and one species from a Mexican freshwater cave. third Indo-West
Pacific species, P. darmniensis, from mangroves in Darwin Harbour, Northern
Territory, is described and illustrated. The new species is closely related to the
other Indo-West Pacific species, and a key is provided for their identification.
The first species of the genus Potamal- Potamalpheops Vo^^qM, 1979
pheops to be discovered was P. haugi, de- Potamalpheops darwiniensis, new species
scribed by Coutiere (1906) as Alpheopsis Figs. 1-3
haugi, from Gabon. Subsequently Sollaud —
Material examined. 16, holotype, sta-
(1932) described Alpheopsis monodi from tion JRH 2-Q3-(M), Hudson's Creek, Dar-
the Cameroons and Senegal. Hobbs (1973)
win Harbour, Northern Territory, Austra-
significantly extended the range ofthe genus
lia, 12°28.75'S, 130°55.67'E, 23 Feb 1991,
Alpheopsiswhen reportingA. stygicola, from
intertidal, coll. J. R. Hanley, Northern Ter-
a freshwater cave at Oaxaca, Mexico. Pow- ritory Museum Cr. 007922.
ell (1979) recorded a third African species,
Description of holotype. -Simill, of sub-
P. pylorus, from Nigeria and designated the
cylindrical body form, body slightly com-
genus Potamalpheops to include also the
pressed, with the distal part of left third
earlierdescribed species. Hobbs (1983) con-
maxilliped and second pereiopod missing,
cluded that A. stygicola should also be in-
right second pereiopod in early stage ofre-
cluded in the genus Potamalpheops. Re-
generation.
cently, Bruce (1991) reported the first
Rostrum (Fig. 2A, B) very short, scarcely
occurrence of the genus in the Indo-West
exceeding anterior margin ofcornea, acute,
Pacific region, with P. hanleyi from Darwin
broadly triangular in dorsal view, dorsal ca-
Harbour, Australia, and then the presence
rina obsolete, ventral carina feebly devel-
of a second troglobitic species, P. pininsu-
lae, from the Isle ofPines, New Caledonia. oped, unarmed, lateral carinae broad, con-
fluent with orbital margin.
The presence ofanother West African spe-
Carapace depilate, smooth; orbital mar-
cies, in the Calabar River, has been indi-
gin concealing major portion of eye (Fig.
cated by Powell (1979), but this species is
A 2B), with very feebly developed, rounded,
still undescribed. second Australian spe-
antennal region, pterygostomial angle
cies has recently been collected and is here
slightly produced, bluntly angular, ventral
described and illustrated.
margin with numerous plumose setae; car-
diac notch distinct.
Systematic Account
Abdomen
depilate, glabrous; sixth seg-
Alpheidae Rafinesque, 1815 ment (Fig. 2H) about 1.2 times length of
VOLUME NUMBER
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Fig. 1. Potamalpheopsdarwiniensis, new species, holotype male, Hudson's Creek, Darwin. Scale bar in mm.
fifth, 1.5 times longer than deep, com- Antennule (Fig. 2E)with pedunclerobust,
pressed, posterior lateral angle acute, pos- about 0.4 ofcarapace length, distinctly ex-
teroventral angle with articulated triangular ceeding scaphocerite and carpocerite; prox-
plate; pleura of first four segments broadly imal segment about 1.4 times longer than
rounded, fifth subrectangular, posteroven- proximal width, distodorsal margin non-
tral angle subacute. Telson (Fig. 2K) about dentate, with well developed ventromedial
1.25 timeslengthofsixth segment, 1.8 times carina; statocyst normally developed; with
longer than anterior width, lateral margins broad acute stylocerite reaching distally to
straight, posteriorly convergent, with small anterior margin of segment; intermediate
dorsal spines, about 0.07 of telson length, segment subcylindrical, about 1.1 times
anterior pair at 0.3 of telson length, poste- proximal segment length, 2.0 times longer
riorpairatabout0.6 (spine missingonright); than wide, ventromedial border with long
posterior margin (Fig. 3G) broad, about 0.6 plumose setae; distal segment subcylindri-
of anterior width, with 2 pairs of robust cal, about 0.5 of intermediate segment
subequal subventral spines laterally, about length; upper flagellum biramous, proximal
3.0 times length of dorsal spines, central 13 segments fused, shorter ramus with sin-
portion of posterior margin semicircular, gle free segment only, with about 8 groups
occupying about half posterior margin of aesthetascs; lower ramus slender, fili-
width, with about 20 long plumose setae, form, subequal to longer upper ramus length
with numerous short slender simple spi- (tips of rami missing).
nules dorsally; anal tubercles feebly devel- Antenna (Fig. IF) with stout basicerite,
oped. with small acute process projecting laterally
700 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Fig. 2. Potamalpheops darwiniensis, new species, holotype male. A, Anterior carapace and antennal pedun-
cles, dorsal. B, Anterior carapace, lateral. C, Eye, lateral. D, Same, dorsal. E, Antennularpeduncle. F, Antennal
peduncle. G, Epipod offirst pereiopod. H, Sixth abdominal segment, lateral. I, Endopod ofsecond pleopod. J,
Same, appendices interna and masculina. K, Telson. L, Uropod.
VOLUME NUMBER
106, 4 701
Fig. 3. Potamalpheops daminiensis, new species, holoupe male. A. Right first pereiopod. B. Same, chela.
C. Same, fingers. D. Right third pereiopod. E, Same, propodanddactyl. F. Endopodoffirst pleopod. G. Posterior
margin oftelson. H, Uropod, diaeresis ofexopod, dorsal.
702 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
from anterodorsal margin, with strongacute armed; coxa robust, with 6-setose seto-
ventrolateral tooth, carpocerite robust, dis- branch dorsally, strap-like epipod (Fig. 2G)
tinctly exceeding distal margin of scapho- laterally.
cerite, subcylindrical, slightly compressed, Second pereiopod (left) with proximal
about 3.0 times longer than wide, flagellum carpus and proximal segments showing no
long, slender, 2.2 times carapace length, special features, coxa with setobranch and
proximal segments not thickened; scapho- strap-like epipod.
cerite reaching to about middle ofdistal seg- Ambulatory pereiopods moderately ro-
ment ofantennular peduncle, 1.8 times lon- bust; third pereiopod (Fig. 3D) slightly ex-
ger than wide, suboval, lateral margin ceeding antennular peduncle by length of
convex, with small acute distal tooth scarce- dactyl, dactyl (Fig. 3E) slender, simple,
ly exceeding broadly rounded anterior mar- curved, compressed, about 0.5 length of
gin of lamella. propod, ventral margin sharply carinate,
Eyes reduced (Fig. 2C, D), largely con- without clearly demarcated unguis, with
cealed by anterior margin of carapace, an- single seta distodorsally; propod (Fig. 3E)
terior surface ofcornea only exposed in dor- about 0.3 ofcarapace length, 6.0 times lon-
sal view, contiguous in midline, cornea ger than wide, uniform, glabrous, with pair
small, well pigmented, peduncle short, sub- of short simple distoventral spines, about
cylindrical, medial surface flattened, with 0.12 of dactyl length, ventrolateral row of
small distinct subacute dorsomedial tuber- 6 small spines, ventromedialrowof4 small-
cle, without setae. erspines; carpus about 0.6 ofpropodlength,
Mouthparts not dissected. Third maxil- 3.2 timeslongerthandistalwidth, with small
liped extending to distal end of antennular distoventral spine; merus 1.35 times longer
peduncle, terminal segment tapering distal- than propod, 5.2 times longer than wide,
ly, obliquely truncate, with 4 stout spines, uniform, with large mobile ventrolateral
largest spine strongly comified; coxa with spines at 0.38 and 0.68 of length; ischium
strap-like epipod. about 0.5 ofmerus length, 2.4 times longer
First pereiopods (Fig. 3A) subequal, sim- than distal width, strongly tapered proxi-
ilar, chelae appearing to be carried in flexed mally, with single small mobile spine ven-
position; chelae (Fig. 3B) robust, slightly trolaterally; basis normal; coxa robust, with
longeronleft, slightlystouteronright, about 6-setose setobranch dorsally, strap-like epi-
0.4 ofcarapace length, palm subcylindrical, pod laterally. Fourth pereiopod similar to
shghtly swollen, compressed, smooth, about third. Fifth pereiopod similar to fourth,
1.65 times longer than deep, fingers (Fig. more slender, dactyl 0.5 of propod length,
3C) stout, about 0.6 of palm length, feebly propod 6.0 times longer than wide, 0.55 of
subspatulate, with very stout, strongly cor- carapace length; merus with proximal ven-
nified, blunt, feebly bidentate tips, dactylus trolateral spine; ischium unarmed; coxawith
about 2.8 times longer than deep, curved, setobranch, without epipod.
with entire sharp unarmed cuttingedge; car- Abdominal stemites with narrow trans-
pus stout, about 0.28 of chela length, 0.45 verse ridges between bases ofpleopods, un-
ofpalm length, distally excavate, unarmed, armed.
with about 7 transverse rows of long ser- Pleopods normal. Endopod offirst pleo-
rulate cleaning setae ventromedially; merus pod (Fig. 3F) slender, 3.6 times longer than
about 0.5 of chela length, 2.4 times longer basal width, curved, tapering distally, with
than wide, uniform, ventral surface feebly 1 1 plumose setae medially, 17 similar setae
excavate, unarmed; ischium about 0.38 of distally and laterally, distal setae longer,
chela length, 2.0 times longer than distal about 0.6 of endopod length. Endopod of
width, tapered proximally, unarmed; basis second pleopod (Fig. 21) 5.0 times longer
obliquely articulated with ischium, un- than wide, with appendices at 0.38 oflength;
VOLUME NUMBER
106, 4 703
appendix masculina (Fig. 2J) subcylindri- short plumose setae at the pterygostomial
cal, 7.0 times longer than wide, with 4 long angle; (4) the subrectangular, posteroven-
simple terminal spines, about 0.6 ofcorpus trally subacute pleuron ofthe fifth abdom-
length, 3 similar spines distomedially; ap- inal segment; (5) dorsal telson spines at 0.3
pendix interna short, reaching to middle of and 0.6 oftelson length; (6) convex central
appendix masculina corpus, with few distal portion ofposterior margin oftelson more
cincinnuli. than halfposteriormargin width, with more
Uropod (Fig. 2L) with protopod bearing numerous plumose setae; (7) proximal seg-
large acute distodorsal lobe, rami slightly ment of antennular peduncle with disto-
exceeding posterior telson margin; exopo- dorsal margin lacking denticulations, ven-
dite 2.3 times longer than wide, greatest tromedial carina distally subrectangular; (8)
widthat0.6 oflength, lateral margin slightly basicerite with acute distolateral process
convex, with well developed submarginal dorsally; (9) carpocerite distinctly exceeding
setal fringe, distolateral angle subrectangu- scaphocerite; (10)scaphocerite ovalin shape,
lar, with large mobile spine medially, di- with distolateral tooth scarcely exceeding
aeresis (Fig. 3H) well developed with den- lamella; (11) eye markedly reduced, largely
tate dorsal flange laterally extending across concealed by anterior carapace, cornea
about 0.8 of width, with about 24 small small, eyestalk flattened medially with small
subuniform acute teeth (tips ofmanyabrad- acute dorsomedial tubercle; (12) first pe-
ed), distal lamella large, broadly rounded, reiopods with robust chelae; (13) third am-
highly flexible, with short simple spiniform bulatory pereiopod with propod more slen-
marginal setaedistolaterally, otherwisewith der, 6.0 times longer than distal width, with
long densely plumose marginal setae; en- ventromedial and ventrolateral spine rows;
dopodite about 0.9 of exopod length, 2.2 (14) male first pleopod endopod elongate,
times longer than wide. tapering, curved, with numerous long plu-
Measurements. —Carapace length 6.2 mose setae distomedially; (15) male second
mm, total body length (approx.) 17 mm. pleopod endopod with appendices arising
Etymology. —Sx>QQi^c name derived from at less than half medial margin length, ap-
locality ofcapture, Darwin Harbour. pendix masculina with 7 longer spines dis-
—
Habitat. *'Mud-mound," amongst tally; (16) exopod ofuropodwith distolater-
mangroves. alangle subrectangular, diaeresiswith about
Affinities. —Potamalpheops darwiniensis 24 small acute denticles.
is closelyrelatedto the two otherIndo-West Potamalpheus darwiniensis is readily dis-
Pacific species, both ofwhich belong to the tinguished from the only other Indo-West
species group characterized by the presence Pacific species, P. pininsulae, by its lack of
of two pairs of posterior telson spines in- a long, slender, acute, ventrally dentate ros-
stead ofthree. This group also includes the trum.
West African species P. monodi (Sollaud,
Discussion
1932), from Cameroon and Senegal.
Potamalpheops darwiniensis is most Little is known about the precise ecolog-
closely related to P. hanleyi, which is also ical niche occupied by the various species
known only from Darwin Harbour. Pota- ofthe genus Potamalpheops. The collection
malpheops darwiniensis may be distin- ofthe single specimen ofthe present species
guished from P. hanleyi by the following from a "mud-mound" suggests the possi-
features:—(1) the presence ofa much short- bility that this species may be associated
er rostrum, only slightly exceeding feebly with some burrowing invertebrate. Man-
produced blunt extracomeal teeth; (2) the grove "mud-mounds" are commonly pro-
feebly produced antennal and pterygosto- duced by annelids or decapod crustaceans,
mial angles; (3) the presence of numerous particularly thalassinids. No Indo-West Pa-
704 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
cific caridean shrimps are so far known to cle; eyes well developed, cornea
associate with thalassinideans. largely exposed by anterior margin
The discovery of a third species of Po- of carapace; extracorneal tooth
tamalpheops in the Indo-West Pacific re- acute; first pereiopods feebly devel-
gion clearly establishes this genus a com- oped, with small chelae; diaeresis of
ponent of its fauna. It seems likely that exopod of uropod with about 18
additional specimens or species of these acute teeth .... P. hanleyi Bruce, 1991
shrimps, which are so far known only from
very shallow coastal or fresh waters, will be
found in due course, and will link the east- Acknowledgment
em
distribution of the Indo-West Pacific I am most grateful to my colleague, Dr.
species with those with the West African
J. R. Hanley, for bringing this specimen to
species. my
attention.
The Mexican species, P. stygicola, may
be less closely related to the other species
Literature Cited
of the genus, from which it differs by the
presence of a remarkable longitudinal he- Bruce, A. J. 199L The "African" shrimp genus Po-
patico-branchiostegal groove (Hobbs 1973) tamalpheops in AustraUa, with the description
ofP. hanleyi, new species (Decapoda: Alphei-
that cannot be discerned in the other non-
dae).—Journal ofCrustaceanBiology 11(4):629-
Mexican species. Potamalpheops stygicola
634.
could well have had an independent evo- . 1992 [1993]. Potamalpheops pininsulae sp.
lutionary origin from the other species of nov., a new stygiophilic shrimp from New Cal-
the genus Potamalpheops and may belong edonia (Crustacea: Decapoda: Alpheidae).—
Stygologia 87(4):231-242.
to a separate genus.
Coutiere,H. 1906. SurunnouvelleespecedM/p/zeop-
sis, A. haugi, provenantd'unlacd'eaudoucedu
Key to the Indo-west Pacific Species of bassindeI'Ogoue(VoyagedeM.Haug, 1906).—
Potamalpheops Powell Bulletindu Museumd'HistoireNaturelle, Paris
12:376-380.
1. Rostrum well developed, reaching Hobbs, H. H., Jr. 1973. Twonewtroglobiticshrimps
to distal margin of proximal seg- (Decapoda: AlpheidaeandPalaemonidae)from
ment of antennular peduncle, with Oaxaca, Mexico.—AssociationofMexican Cave
Studies, Bulletin 5:73-80.
single acute ventral tooth
1983. The African shrimp genus Potamal-
.
P. pininsulae Bruce, 1993 pheops in Mexico (Decapoda, Alpheidae).—
- Rostrum short, not nearly reaching Crustaceana 44(2):221-224.
distal margin of proximal segment Powell, C. B. 1979. Three alpheid shrimps ofa new
of antennular peduncle, ventrally genusfromWestAfricanfreshandbrackishwa-
unarmed 2 ters: taxonomy and ecological zonation (Crus-
taceaDecapodaNatantia).—RevuedeZoologie
2. Rostrum very short, not reaching Africaine 93:116-150.
bases ofantennular peduncles; eyes Rafinesque, C. S. 1815. Analyse de laNature ouTa-
reduced, largely covered by anterior bleau de rUnivers et de ses Corps organises,
carapace; extracomeal tooth obso- Palermo, Sicily, 1-224.
Sollaud, E. 1932. Sur un alpheide d'eau douce, Al-
lescent; first pereiopods well devel- pheopsis monodin. sp., receuUiparM. Th. Mo-
oped, with robust chelae; diaeresis nod au Cameroun.—Bulletinde la SocieteZoo-
ofexopod ofuropod with about 24 logique de France 57:375-386.
small acute denticles
P. darwiniensis, new species Division of Natural Sciences, Northern
- Rostrum exceeding middle ofprox- TerritoryMuseum, P.O. Box 4646, Darwin,
imal segment ofantennular pedun- Australia 0801.