A New Species Of Freshwater Anomuran Crab Of The Genus Aegla Leach, 1821 (Crustacea : Decapoda : Aeglidae) From The Nahuelbuta Coastal Range, Chile

10 Pages·2003·6.5 MB·English

by  C G Jara

PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
116(4):933-942. 2003.
A new species of freshwater anomuran crab of the genus Aegla
Leach, 1821 (Crustacea: Decapoda: AegUdae) from the Nahuelbuta
Coastal Range, Chile
Carlos G. Jara, Marcos Perez-Losada, and Keith A. Crandall
(CGJ) Institute de Zoologia, Universidad Austral de Chile, Campus Isla Teja, Casilla 567,
Valdivia, Chile, e-mail: [email protected];
(MP-L, KAC) Department of Integrative Biology, Brigham Young University, 401 WIDB Provo,
Utah 84602-5181, U.SA., e-mail (MP-L): [email protected],
e-mail (KAC): [email protected]
—
Abstract. Aegla occidentalis, a new species of the family Aeglidae, is de-
scribed from the Tucapel River basin, on the western slope of the Nahuelbuta
Coastal Range, in Chile. Morphologically, the new species closely resembles
A. laevis (Latreille) from Central Chile but differs in having the apex of the
carpal lobe of the chelipeds topped by two to four blunt scales mixed with a
group of short, stout setae, the dorsum of the palmar crest slightly, if at all,
concave, and the distal half of the subligulate rostrum not distorted. The mor-
phological similarity between A. occidentalis and A. laevis contrasts with the
high degree of genetic divergence between these two taxa, based on mtDNA
sequence analysis. Our molecular results show A. occidentalis and Aegla ba-
hamondei Jara to be sister species, with a 1.4%-1.6% average pairwise se-
quence divergence, compared with 5.9%-7.4% between A. occidentalis and A.
laevis.
The anomuran freshwater crabs of the Such was the case when —2.6 kb from the
genus Aegla Leach, 1821 are found in riv- mitochondrial genes 12S, 16S, COI and
ers and lakes of southern South America coil were sequenced for most of the Aegla
(Schmitt 1942), displaying a vast array of species occurring in the continental territo-
minute morphological differences in the ry of Chile to reconstruct their phylogenetic
shape and ornamentation of carapace and relationships (Perez-Losada et al. 2002).
appendages (Bond-Buckup & Buckup Some of the specimens collected in the
1994). However, the group is constrained to River Tucapel, Province of Arauco, on the
a rather conservative general morphotype western slope of Nahuelbuta Coastal
that renders the discrimination of most spe- Range, and provisionally assigned by Jara
cies difficult (Schmitt 1942). By necessity, (1996) to Aegla araucaniensis Jara, 1980,
all known species of Aegla have until now were subsequently linked to A. bahamondei
been discriminated and diagnosed on the Jara, 1982 by molecular analysis (Perez-Lo-
basis of discrete combinations of morpho- sada et al. 2002). In this study, the speci-
logical characters, and therefore the exis- mens of River Tucapel are described as a
tence of cryptic or sibling species (sensu new species. The type material and other
Mayr & Ashlock 1991) cannot be ruled out. reference specimens were deposited in the
Molecular techniques can potentially reveal Crustacean Collection of the Instituto de
levels of genetic differentiation among pop- Zoologia of the Universidad Austral de
ulations ofAegla hidden within morpholog- Chile (IZUA-C), Valdivia, Chile. The size
ically similar populations (Hillis 1987). of specimens was recorded as carapace
934 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
length (CL), measured between the tip of Lieu Lieu, at Puerto Choque, 38°ir43"S,
rostrum and posterior margin of the cara- 73°21'21"W, 8 Dec 1981, coll. R. Arriaga-
pace. da, IZUA C-260.
—
Diagnosis. Body contour almond
Aegla occidentaliSy new species shaped; carapace surface grossly punctated;
Figs. 1, 2 rostrum triangular to subligulate, short and
— low profiled, apex with scale surrounded by
Aegla "not yet identified". Jara, 1982:
rosette of short stiff setae and minute acic-
235 (see Remarks).
—
ular scales; orbital spine absent; branchial
Aegla araucaniensis. Jara, 1996:63, 194,
margins of carapace not expanded, smooth;
195, fig—s. 42, 43 (in part, see Remarks). anterolateral angle of second abdominal
Aegla sp. Perez-Losada et al., 2002:305.
epimeron blunt, frequently with small scale
—
Material examined. Holotype: S, CL hidden among short setae; carpal lobe sub-
28.3 mm. River Tucapel, at Quelen Quelen, pyramidal tipped with row of 1-4 scales in
m
100 eastward from bridge at national a row mingled with short stiff setae; lobe
roadway P-60-R, 7 km N of Canete, on proximodorsal end of dactylus of chelae
m
37°44'09"S, 73°22'49"W, 40 above sea low and blunt; palmar crest subrectangular,
level, Arauco, VIII Region, Chile, 7 Dec slightly expanded and faintly concave, its
1974, colls. C. G. Jara, C. A. Moreno, and margin subdenticulate; fourth thoracic ster-
J. N. Arenas, IZUA C-66A. Allotype: $, num flat, unornamented, at most with semi-
CL 19.0, same data as holotype, IZUA C- circular swelling ending abruptly at frontal
66A. Paratypes: 2 S S, CL 17.5, 21.7; ?, end. —
CL 14.3, same data as holotype, IZUA C- Description ofholotype. Body (Fig. la)
66A. almond-shaped in contour; precervical por-
Non-paratype material: 6 ? ?, CL 16.2, tion clearly distinct from postcervical; car-
17.6, 18.2, 18.5, 18.6, 19.5; c^, CL 15.5, apace most protuberant and convex on gas-
same data as holotype, 19 Nov 1975, coll. tric area. Carapace surface with coarsely,
C.G.Jara, IZUA C-156. 9, CL 16.1; 5 c^ (5, shallow punctae, with pappose setae. Ros-
CL 17.0, 17.9,18.5, 18.6, 25.5, same data trum subligulate, straight, at same level of
as holotype, 18 Sep 1981, coll. C. G. Jara, front; margins, from orbital sinus to tip,
IZUA C-429. 2 $ 9, CL 18.0, 18.9; ASS, with row of tiny scales; rostral carina ex-
CL 16.5, 17.4, 18.3, 19.8, same data as ho- tended from point equidistant to protogas-
m
lotype but 100 westward from bridge, 22 tric eminences to distal third of rostrum,
Feb 2000, colls. C. G. Jara, M. Perez-Lo- and merging beyond that point into rostrum
sada, and A. Riedemann, IZUA C-592. 3 body (Fig. Ig). Space between carina and
9 9, CL 7.9, 19.8, 22.5; 2 S S CL 17.9, margins not noticeably troughed; carina
22.8, River Caramavida, 37^41' 16"S, summit with 2 irregular rows of tiny acute
73°21'27"W, 05 Nov 1981, coll. C. G. Jara, scales. Rostrum tip with small, acute, con-
IZUA C-242. 2 9 9, CL16.2, 16.9; ASS ical scale flanked by flat scales at base;
CL 18.9, 19.8, 21.0, 24.8, River Pocuno, 2 scales interspersed with minute, stiff, pap-
km north from Colonia Antiquina, under pose setae. Ventral surface of rostrum pro-
bridge of national roadway S-70, truding as blunt keel, reaching deepest point
38°02'07"S, 73°23'37"W, 11 Dec 1981, coll. between and behind ocular peduncles. Or-
C. G. Jara, IZUA C-428. 2 9 9, CL 18.1, bits broad, deeply U-shaped, without orbital
18.7; A SS,CL 16.7, 18.8, 19.4, 20.2, Lake spine or extraorbital sinus (Fig. la). In
Lanalhue, 37°55'37"S, 73°15'18"W, 7 Nov place of extraorbital sinus 2 minute scales
1974, colls. C. G. Jara, C. A. Moreno, and protruding from slanted margin merging
J. N. Arenas, IZUA C-65. 2 9 9, CL 13.6, with anterolateral lobe of carapace; lobe
13.8; A SS,CL 15.8, 15.8, 16.0, 20.8, Lake tipped with a cuspidate scale, and posterior
VOLUME NUMBER
116, 4 935
Fig. 1. Aegla occidentalis, new species, a, male holotype (IZUA C-66A), dorsal view; b, female allotype,
dorsal view; c-g, male holotype; setae mostly omitted: c, left cheliped, ventral view; d, third and fourth sterna,
ventral view; e, telson plate and sixth abdominal somite, dorsal view; f, second abdominal epimeron; g, pre-
cervical portion of carapace, side view.
936 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
to it with row of 12 (left) or 14 (right) mi- todorsal margin smooth, bearing scattered
nute, size-decreasing scales extending on minute scales and short stiff pappose setae
lateroexternal margin. Protogastric emi- more numerous and closely packed on mid-
nences nodular, bearing 6 (left) or 8 (right) dorsal low profiled tubercle; ventrolateral
irregularly placed minute blunt scales. Epi- inner margin slightly sinuous, bearing row
gastric eminences low, rounded, not well of 3 minute scales, and pronounced acu-
defined, bearing patch of minute scales, minate conical tubercle distally; ventrolat-
some arranged in semicircular row on fron- eral outer margin smooth, with 1 (left) or 2
tal edge with remaining scales spreading (right) spiniform tubercles distally; with an-
backwards over somewhat triangular area. other small acuminate tubercle distally and
Hepatic area wide, margin slightly upturned close to article margin. Carpus markedly
and bearing row of minute scales; antero- convex, globose, almost smooth, bearing
lateral angle of first right hepatic lobe scattered minute scales irregularly distrib-
tipped with acuminate scale larger than that uted, larger and more prominent on distal
on left side. Second and third lobes distinct, margin; carpal ridge slightly protuberant,
blunt. Epibranchial tooth pyramidal, well and nodulated, bearing few minute scales;
defined but not particularly elongated, tubercles (1 left, 2 right), each with 3 scales
tipped with small acuminate scale followed in oblique row on apex; dorsomesial margin
by row of 5 (right) or 7 (left) tiny scales on of carpus with 4 large proximally size-de-
lateroexternal margin. Margin of anterior creasing conical tubercles in a row; tuber-
branchial areas thin, almost smooth, slightly cles thick, tipped with moderately acute
expanded, bearing homogeneous band of scales; frontmost tubercle on left carpus
tiny scales mingled with short stiff pappose with accessory scale some distance behind
setae. Posterior branchial margin non-re- apical one, and separated from low-profiled
curved, somewhat thickened, with band of carpal lobe by wide sinus (Fig. Ic). Carpal
scales and setae extending to posterior car- lobe broad-based, subtriangular in outline,
apace rim. Cardiac area subrectangular, flattened, tipped with row of 3 or 4 short
slightly longer than wide. Areola rectan- coalescent scales interspersed with short
gular (length/width ratio = 1.5), not notice- stiff pappose setae. Ventral face of carpus
ably protuberant. Sternal surface of cara- (Fig. Ic) clean, smooth, bearing 1 short
pace not ornamented. Central portion of stout acuminate tubercle on central area sur-
fourth thoracic sternum slightly protuberant rounded by few long stiff simple setae;
(Fig. Id), bearing patch of long stiff simple right carpus with second acuminate tubercle
setae on frontal edge. Dorsum of abdominal close to base of third tubercle of dorsome-
somites covered by short stiff pappose setae sial carpal margin; corresponding site on
especially dense on epimera. Anterolateral left carpus with slightly protuberant swell-
angle of second abdominal epimeron as ing. Ventral margin of carpus with minute
short acuminate tubercle ending in scale scale on carpus-propodus articular knob.
concealed by short stiff pappose setae (Fig. Propodus inflated, markedly convex (partic-
If). Lateroventral angle of third and fourth ularly left); dorsal surface covered by mi-
epimera also tipped with acute scale. Telson nute lens-like scales variously arranged,
subpentagonal, slightly wider than long, and becoming more dense and protruding
clearly divided by mesial joint (Fig. le). on fixed finger. Palmar crest as moderately
Chelae massive, unequal in size, left expanded laminar ridge, with margin irreg-
larger. Basis-ischium ventromesial edge ularly serrated; palmar crest neatly separat-
smooth, slightly nodulated, bearing tiny ed from distalmost pyramidal palmar lobe
conical scale on subdistal knob. Merus dor- by shallow groove; distal margin of palmar
sal edge blunt, bearing row of tubercular lobe blunt, scaly. Left chela cutting edge of
denticles tipped with acuminate scale; dis- molar process with double row of imbricate
VOLUME NUMBER
116, 4 937
—
short transversal corneous scales. Dactylus Table 1. Morphometric ratios of the type series
with slender molar process; dorsal margin specimens ofAegla occidentalis, new species. CL, car-
apace length, between tip of rostrum and median point
with low broad-based corneous tipped tu-
on rear margin ofcarapace; RL, rostral length, between
bercle close to articular furrow. tip ofrostrum and median point between proximal end
Dactylus of second, third, and fourth pe- of orbits; AL, areola length, between frontal and cau-
reiopods long, slender, with elongate, mark- dal midpoints; AW, areola width, between midpoint of
edly recurved corneous tip, especially at lateral grooves of areola; PCL, precervical length, be-
fourth; ventral margin of dactylus with 2— tween tip of rostrum and midpoint of cervical groove;
FW, frontal width, between tips ofanterolateral angles
4 needle-like corneous spines in longitudi- of carapace.
nal row behind tip; distodorsal angle of car-
pus and merus with 1 or 2 tiny, acute scales Mean
confidence
concealed by dense band of short stiff pap- Ratios N Range Mean (Pl<imi0t.s05)
pose setae; frontodorsal margin of carpus
and propodus with dense band of short stiff CL/RL 5.5-5.6 5.5 5.2-5.8
AL/AW
1.3-1.5 1.4 1.2-1.6
pappose setae; same margin of merus with PCL/FW 2.1-2.2 2.1 1.9-2.4
dense row of long soft plumose setae.
—
Description of allotype. Differs from
holotype in having rostral carina flanked by ever, the largest male paratype has blunt an-
troughs on middle third of rostrum. Cara- gles bearing an almost imperceptible scale
pace (Fig. lb) worn out, blackened by de- hidden by setae.
position of organic matter. Chelae less mas- Ventromesial margin of merus of cheli-
sive, unequal in size, left larger. Dorsome- peds with ornamentation varying from
sial margin of carpus of chelipeds with only completely lacking, as in the smallest fe-
3 conical tubercles. Ventral face of carpus male paratypes, to a row of small tubercles,
of right cheliped with 2 coalescent blunt tu- some of which are tipped with a small
bercles, 1 on left cheliped. Lobe on proxi- scale, as in the smallest male paratype.
modorsal end of dactylus of chelae slightly Ornamentation of fourth thoracic ster-
prominent. Ventral margin of dactylus of num, in both male paratypes, with frontal
left second pereiopod with row of 5 slender margin sharp, and convex, forming a rim
acuminate scales behind tip, and row of 3 that is not apparent in the remaining type
scales in the remaining dactyli. specimens.
—
Morphometries. Descriptive morpho- The morphological variation among non-
metries of the type series specimens (see paratype specimens of A. occidentalis is
&
Bond-Buckup Buckup 1994) are record- summarized in Table 2. In addition, among
ed in Table 1.— the specimens from Lake Lanalhue and
Variations. Typically lacking extraor- Lake Lieu Lieu, the rostral carina varies
bital sinus, but in two of the smallest para- from a sharp elevated ridge, stretched along
types both orbits have thickened margin the whole rostrum, to a ridge restricted to
bearing one small tubercle delimiting a very the proximal third or half of the rostrum;
narrow extraorbital sinus. beyond that it appears flat and apically re-
Apex of carpal lobe of chelipeds typical- curved. The same specimens have a faintly
ly with row of two to four scales mixed marked ridge, with variable intensity, along
with short stiff pappose setae. In the small- the midline of the gastric area behind the
est paratype, both carpal lobes are mono- protogastric eminences. This ridge is also
cuspidate. present in the specimens of River Caramav-
Anterolateral angle of second abdominal ida and River Pocuno but only sporadically
epimeron; it typically protrudes as small tu- among the spec—imens of River Tucapel.
bercle tipped with acuminate scale sur- Distribution. Known from the River
rounded by short stiff pappose setae. How- Paicavi drainage system, which includes the
938 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
—
Table 2. Variation of morphotypic characters in A. occidentalis, new species. Relative frequencies (%) refer
to the number of specimens from each locality examined as non-paratype material, irrespective of sex. River
Tucapel (n = 19), River Caramavida (n = 5), Lake Lanalhue (n = 6), River Pocuno (n = 6), and Lake LleuLleu
=
(n 6).
Localities
Tucapel Caramavida Lanalhue Pocuno LleuLleu
Shape of rostrum:
Triangular 36.8 80.0 33.3 33.3 33.3
Subligulate 63.2 20.0 66.7 66.7 66.7
Troughs both sides of rostrum:
Well marked 52.6 60.0 50.0 50.0 50.0
Faintly marked 47.4 40.0 50.0 50.0 50.0
Orbits: ~
Without spine/tubercle 47.4 60.0 16.7 83.3 50.0
With spine/tubercle 52.6 40.0 83.3 16.7 50.0
Apex of carpal lobe of chelipeds:
With two or more scales 73.7 60.0 83.3 83.3 66.7
With one scale 26.3 40.0 16.7 16.7 33.3
Frontalmost tubercle of dorso-medial margin of carpus of chelipeds:
Monocuspid 94.7 80.0 83.3 100.0 100.0
Bicuspid 5.3 20.0 16.7 0.0 0.0
Anterolateral angle second abdominal epimeron:
Armed with scale 63.2 60.0 33.3 50.0 83.3
Unarmed 36.8 40.0 66.7 50.0 16.7
Angle of third abdominal epimeron:
With acuminate scale 15.8 0.0 50.0 0.0 0.0
Blunt 84.2 100.0 50.0 100.0 100.0
Angle of fourth abdominal epimeron:
With acuminate scale 89.5 100.0 83.3 66.7 66.7
Blunt 10.5 0.0 16.7 33.3 33.3
River Tucapel, the River Caramavida and probably close to hatching. Also, five of the
Lake Lanalhue, and from the River Lieu six females from River Tucapel (IZUA C-
Lieu drainage system, which includes the 156) had fresh, empty egg-shells, indicating
River Pocuno and Lake Lieu Lieu (Fig. 2). that the juveniles hatched only a few days
Both systems drain contiguous sections of before collection. Therefore, it is likely that
the western slope of the Nahuelbuta Costal recruitment in populations of A. occiden-
Cordillera, between 37°40'S —and 38°15'S. talis occurs in springtime (September to
Notes on natural history. The general November), as in other species of Aegla
&
description of the biotope where A. occi- (see Bahamonde Lopez 1961, Lopez
dentalis, new species, lives was published 1965, Rodrigues & Hebling 1978).
—
by Jara (1982) with the description of A. Etymology. The specific name is from
bahamondei, a species with which the for- the Latin occidentalis, western, in allusion
mer coexists. to the geographic distribution of the new
The females of A. occidentalis collected species, which is apparently restricted to a
in the River Caramavida (IZUA C-242) section of the drainage system of the west-
were ovigerous. Their eggs contained em- ern slope of the Nahuelbuta Coastal Cor-
bryos in advanced state of development, dillera.
VOLUME NUMBER
116, 4 939
45
37*35'
37*45'
38*00
-48*
38*15'-
Fig. 2. Collection localities (stars) of Aegla occidentalis, new species, in the Tucapel and Pocuno river
systems. Arrow indicates type locality.
—
Comparisons. Aegla occidentalis, new tubercular lobe on the dorsum of the dac-
species, closely resembles A. laevis (La- tylus of the chelae. Furthermore, with A.
treille, 1818), and A. araucaniensis. The laevis it shares the blunt slightly protruding
new species shares with those two species epigastric eminences, the non-recurved pos-
the almond-shaped body contour, the rela- terior branchial margin, and the low pro-
tively short precervical section and narrow filed carpal lobe.
front, the absence of orbital spine, the ele- Aegla occidentalis differs from the other
vated gastric area, the broad areola, the un- almond-shaped species by having the dorsal
ornamented branchial margins, the scale surface of the carapace grossly punctated, a
ending rostral apex surrounded by rosette feature most evident in specimens with old,
of short stiff pappose setae and minute acic- darkened carapaces, and by having the an-
ular scales, the subligulate rostrum, the sub- terolateral angle of the second abdominal
rectangular denticulate palmar crest, and the epimeron rounded and frequently without
940 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
an apical scale (see Table 2). The palmar Losada et al. 2002), which provided a high-
crest in A. occidentalis, although subrect- resolution approach to assess taxonomic
angular, is slightly to moderately expanded, limits. The existence of similar morpholo-
with the margin weakly serrate, and faintly gies in two or more species may be due to
concave on the dorsum. In that respect it close phylogenetic relationship (descen-
differs from A. araucaniensis, in which the dents from a common recent ancestor), or
palmar crest is clearly expanded, markedly to morphological convergence. Conver-
indented, and dorsally concave especially at gence may result from the independent evo-
its posterior end; and from A. laevis, which lution of the same specialized (adaptive)
has a less expanded but similarly concave features in response to similar selective
posterior ending palmar crest. The morpho- pressures, or to retention of a generalized
&
logical differences between A. occidentalis ancestral morphotype (Moore Willmer
and the above mentioned species are subtle, 1997). In the present case, the comparison
and subject to considerable variation but of A. occidentalis with other species ofAe-
still enough to distinguish the species. From gla indicates that the morphotype of the
A. bahamondei it differs in lacking acute, new species is markedly similar to that of
apically elongate, conical rostrum; dentic- A. laevis and A. araucaniensis. The genetic
ulate branchial margin; protuberant proto- divergence and phylogenetic analysis
gastric eminences; anterolateral angle of (Perez-Losada et al. 2002) of four mito-
second abdominal epimeron spiniform; chondrial genes from 16 Chilean aeglids
fourth thoracic sternum with median acute, suggest that the species most closely related
conical, tubercle; and spine-like dactylar to A. occidentalis is A. bahamondei, a spe-
lobe of chelae (Jara 1982). cies from which the former clearly differs
Genetically, A. occidentalis shows clear in morphology (Jara 1982), and the two oc-
differences from all other Chilean species cupy the same biotope. The high degree of
analyzed by Perez-Losada et al. (2002). Ac- genetic divergence between A. occidentalis
cording to those authors, the interspecific and A. araucaniensis (3.5%-3.7%) and be-
degree of average pairwise genetic diver- tween A. occidentalis and A. laevis (5.9%-
gence estimated from the corrected genetic 7.4%), and their clearly separated phylo-
distances ranges from 1.3%-9.9%. The pair genetic positions in the maximum likeli-
A. occidentalis—A. bahamondei has the low- hood and maximum parsimony trees (see
est divergence, 1.4% to 1.6%, a value sim- Perez-Losada et al. 2002), suggest the pos-
ilar to that observed for other pairs (e.g., A. sibility of morphological convergence rath-
&
cholchol Jara Palacios, 1999-A. rostrata er than the sharing of a generalized ances-
Jara, 1977 = 1.3% to 1.5%), and higher tral morphotype. In contrast, the inferred
than that observed in pairs of subspecies close relationship between A. occidentalis
(e.g., A. denticulata lacustris Jara, 1989-A. and A. bahamondei, and the fact that they
=
denticulata denticulata Nicolet, 1849 share the same biotope with no appreciable
0.3% to 0.4%), or in populations of a single differences in density (C. G. Jara, pers.
=
species (e.g., A. affinis Schmitt, 1942 obs.), suggest an evolutionary and geo-
0.2%). Thus, these data suggest that the ge- graphic scenario that allowed for the allo-
netic differences observed between A. oc- patric speciation of both taxa, and for their
cidentalis and A. bahamondei are indicative subsequent concurrence in the same river
of species distinctness within the Aeglidae. basin.
—
Remarks. The discovery of the new The specimens of Aegla "not yet iden-
species A. occidentalis was facilitated by tified" mentioned by Jara (1982) have
the application of molecular techniques in proven to represent the new species A. oc-
the study of phylogenetic relationships cidentalis. As previously mentioned, part of
among the Chilean species ofAegla (Perez- the material ofA. araucaniensis reported by
—
VOLUME NUMBER
1 16, 4 941
—
Jara (1996), contains specimens of A. oc- approaches to systematics. Annual Review
of Ecology and Systematics 18:23-42.
cidentalis.
—
Conservation. From a conservation lUCN. 2001. lUCN Red List Categories (2001): ver-
sion 3.1. Prepared by the lUCN Species Sur-
perspective, A. occidentalis qualifies as
vival Commission. lUCN, Gland, Switzerland
"Vulnerable" (VU) according to the crite-
and Cambridge, UK.
ria included in the lUCN (2001) Red List
Jara, C. G. 1977. Aegla rostrata n.sp., (Decapoda,
Categories, because, with only five recog- Aeglidae), nuevo crustaceo dulceacuicola del
—
nized localities, its populations are likely Sur de Chile. Studies on Neotropical Fauna
fragmented and restricted in distribution and Environment 12:165-176.
due to severe perturbations in the river ba- 1980. Dos nuevas especies de Aegla Leach
.
sins of the western slope of the Coastal (Crustacea, Decapoda, Anomura) del sistema
—
Cordillera by intense logging activities (cri- hidrografico del Rio Valdivia. Anales del
Museo de Historia Natural de Valparaiso
terion D2).
(Chile) 13:255-266.
1982. Aegla bahatnondei, new species
Acknowledgements .
(Crustacea: Decapoda: Anomura) from the
The authors acknowledge the assistance Coasta—l Mountain Range of Nahuelbuta,
of: Mr. R. Arriagada and Mr. A. Riedemann Chile. Journal of Crustacean Biology 2:
232-238.
during collecting trips to the Nahuelbuta
Cordillera, and all persons who gladly con- . 1989. Aegla denticulata lacustris, new sub-
species, from Lake Rupanco, Chile (Crusta-
tributed to, or assisted in, collecting speci- cea: Decapoda: Anomura: Aeglidae).—Pro-
mens of Aegla occidentalis for the Crusta- ceedings of the Biological Society of Wash-
cean Collection of the Instituto de Zoologia ington 102:385-393.
We
of the Universidad Austral de Chile. 1996. Taxonomia, sistematica y zoogeogra-
.
thank also the associate editor and referees fia de las especies chilenas del genero Aegla
for their efforts in improving the readability Leach (Crustacea: Decapoda: Anomura: Ae-
of the text. The present contribution was glidae). Ph.D. thesis, Escuela de Graduados,
Universidad de Concepcion, Concepcidn,
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