the genus Fluviopupa on the Austral Islands

Transcription

Molluscan Research 25(3): 145–163
http://www.mapress.com/mr/
ISSN 1323-5818
Magnolia Press
Rissooidean freshwater gastropods from the middle of the Pacific:
the genus Fluviopupa on the Austral Islands (Caenogastropoda)
M. HAASE1,2, O. GARGOMINY1 & B. FONTAINE1
1
Muséum National d'Histoire Naturelle, Case postale 51, 55 rue Buffon, F-75231 Paris cedex 05, France
Present address and address for correspondence: Zoologisches Forschungsmuseum Alexander Koenig, Section Molecular Biology,
Adenauerallee 160, D-53113 Bonn, Germany, Tel: 0049 228 91 22 242, FAX: 0049 228 91 22 212, Email: [email protected]
2
Abstract
The Austral Islands comprising five islands of volcanic origin situated in the south of Polynesia, harbour what is probably the
most isolated fauna of hydrobioid gastropods. To date, only two species belonging to the genus Fluviopupa have been known.
We describe an additional four species. Each species is exclusive to one island. Two species each occur on Rapa and Raivavae.
Only on the western-most, oldest, and most degraded island, Rimatara, were no hydrobioids found. The closest relatives occur
on Fiji. Since no hydrobioids are known from the island groups between Fiji and the Austral Islands, viz. Tonga, Samoa and the
Cook Islands, we assume that the common ancestor has arrived directly from Fiji before these islands were formed in the late
Miocene, possibly transported by a bird. Four of the Austral species meet the IUCN criteria for Vulnerable while F. jeanyvesi
n. sp. and F. tubuaia n. sp. are considered Critically Endangered. Both are known from a single locality on Raivavae and
Tubuai, respectively, and they are threatened by habitat loss.
Key words: biogeography, Mollusca, Polynesia, taxonomy
Introduction
The Austral Islands, comprising five islands of volcanic
origin and an uninhabited atoll situated in the south of
Polynesia (Fig. 1) harbour probably the most isolated fauna
of hydrobioid [used sensu Davis (1979) as a descriptive term
for freshwater rissooideans resembling Hydrobia, Hartmann
1821 and not taxonomically; see also Haase et al.(2006)]
gastropods. It is all the more remarkable that two species
from Rapa were found as early as in 1828 by H. Cuming
(Saint John 1940) and 35 years later described by Frauenfeld
(1863). The same species were redescribed under new names
and ascribed to the genus Fluviopupa Pilsbry 1911 almost
100 years later (Hubendick 1952). In a previous paper
(Haase et al. 2006) Fluviopupa has been properly defined
based on anatomical investigation of the type species and
nine new species, all occurring in Fiji. These Fijian species
are geographically the closest hydrobioids to the Austral
species. Other species attributed to Fluviopupa occur on
Vanuatu, New Caledonia, and Lord Howe Island (Solem
1959; Starmühlner 1970; Ponder 1982). However, most of
these species were insufficiently described and their generic
allocation must be considered tentative. In the course of a
project supported by the French Polynesian Government
(Délégation à la Recherche) aiming at inventorying the nonmarine biodiversity of the Austral Islands, two of us (OG and
BF) were responsible for the terrestrial and freshwater
molluscs and have visited the archipelago three times
between 2002 and 2004. Hydrobioids were found on four of
the five islands. Only on Rimatara, the western-most island,
does it appear that hydrobioids are absent. In the present
paper we confirm that the Austral species are congeneric
with those occurring in Fiji. We describe a total of six
COPYRIGHT © 2005 MALACOLOGICAL SOCIETY OF AUSTRALASIA
species, four of them new. Each species occurs on a single
island, and two islands, Rapa and Raivavae, have two species
each.
Material and Methods
Snails were collected during two expeditions to the Austral
Islands in November/December 2002 (Raivavae, Rapa) and
November 2003 (Tubuai, Rurutu), respectively. Collectors
were OG and BF, if not indicated otherwise. Explorations on
Rimatara in November 2004 yielded no hydrobioids. Three
samples collected in November 2002 on Rapa were provided
by P. Lozouet (PL). Individuals were hand picked from leaf
litter, woody debris, stones and aquatic vegetation including
mosses covering rocks in springs and streams. They were
fixed in 95% ethanol. Up to 20 shells were measured under a
dissecting microscope equipped with a measuring graticule.
The total number of whorls (protoconch + teleoconch) were
counted to the nearest eighth of a whorl. Protoconch whorls
were counted to the nearest 10th of a whorl following Verduin
(1982). Prior to dissection, shells were dissolved in ca. 12%
hydrochloric acid. Anatomical drawings were made with a
camera lucida. Usually, three females and three males were
dissected. Hard parts (3-4 shells, 6 opercula, 6 radulae) were
cleaned in 5% sodium hypochlorite for investigation by
scanning electron microscopy (SEM). The head-foot of three
males including the penis was prepared for SEM using
hexamethyldisilazan (Nation 1983). SEM investigations
were conducted in a Jeol JSM 840A Scanning Microscope.
Statistical comparisons were made with PAST 1.27 (Hammer
et al. 2001). Paratypes of new species were only designated
from type localities. Populations investigated anatomically in
145
146
full detail are indicated by an asterisk (*). The remaining
populations were identified based only on shell morphology
HAASE ET AL. (2005) MOLLUSCAN RESEARCH, VOL. 25
and genital anatomy. Figures represent type specimens if not
stated otherwise.
FIGURE 1. Maps of South Polynesia and the four Austral Islands harbouring hydrobioid gastropods. Age of oldest parts of islands in
parentheses (Dupon 1993; Bonneville et al. 2002). Village names are given in capitals, field names in lower case. Arrow points at station
Rp14, where one specimen of F. crassiuscula has been found on land. Altitudes in intervals of 100 m are indicated in shades of darkening
grey. For Rapa, this information was not available. Instead, lines indicate ridges.
AUSTRAL ISLAND RISSOOIDEA: FLUVIOPUPA
Museum acronyms:
AMS, Australian Museum Sydney; BPBM, Bernice P.
Bishop Museum, Honolulu; MNHN, Museum national
d’Histoire naturelle, Paris; NHMW, Naturhistorisches
Museum Wien.
Abbreviations of radular teeth: L, lateral tooth; M1, inner
marginal tooth; M2, outer marginal tooth; R, rhachis =
central tooth.
Systematic descriptions
Fluviopupa Pilsbry, 1911
Type species: Fluviopupa pupoidea Pilsbry, 1911
Synonymy
Fluviopupa Pilsbry, 1911: 549.
Description
Shell: light brown or without colour, clear or
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semitransparent; turriform to globular, mostly blunt-conical;
protoconch well differentiated from teleoconch, surface with
wrinkles gradually becoming finer towards teleoconch;
teleoconch smooth apart from growth lines; umbilicus
narrow; aperture simple, occasionally with varix behind
outer lip, without posterior channel.
Operculum: corneous, yellow, elongate-ellipsoidal,
paucispiral, nucleus submarginal, muscle attachment area
often with white, non-calcareous smear.
External features: epidermis usually black, but
reductions of pigmentation frequent; eyes pigmented;
tentacles without conspicuous pattern of ciliation.
Mantle cavity: ctenidium well-developed with broadly
triangular filaments, abutting directly on pericardium or
connected by short vessel; osphradium ovate-elongate,
usually behind middle of ctenidium; kidney usually
protruding into roof of mantle cavity, renal gland orientated
longitudinally; hypobranchial gland only occasionally
apparent in dissections.
FIGURE 2. Types. A. Fluviopupa deflexa; B. F. rapaensis (= synonym of F. deflexa); C. F. crassiuscula; D. F. obtusa (= synonym of F.
crassiuscula); E. F. raivavaeensis n. sp.; F. F. jeanyvesi n. sp.; G. F. tubuaia n. sp.; H. F. rurutua n. sp. A and C are lectotypes, B and D syntypes, E-H holotypes. Scale bar = 1 mm.
Digestive system: radula taenioglossate, central tooth
with lateral edges at about 45°, U-shaped basal tongue and 35 pairs of basal cusps, innermost largest; lateral tooth with
long, parallel-sided face and well-developed basal tongue,
transition into outer wing ventrally thick but narrow, above
this stalk membranous; marginal teeth with numerous
pointed denticles, longer on inner marginal teeth; stomach
with fan-shaped caecum; intestine bending backwards
around style sac and again forward in front of anterior
chamber of stomach; rectum either running “straight” along
pallial genital glands or making angulation in pallial roof.
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Female genitalia: oviparous; ovary lobate or sacshaped, only occasionally extending to stomach; renal
oviduct coiling first 180º clockwise and then 270º counterclockwise, proximal loop often bent anteriorly or towards
albumen gland; one distal receptaculum seminis globular
with moderately wide, short duct, lying against left side of
bursa copulatrix; bursa copulatrix behind albumen gland
with short duct, pyriform to elongate or large, globular sac;
pallial oviduct with ovate cross section; extent of albumen
gland into pallial roof variable; capsule gland with 2-3
distinct glandular areas; genital opening terminal to
subterminal.
Male genitalia: testis lobate, usually covering proximal
chamber of stomach; vas deferens leaving testis ca. 0.25
whorls proximal to anterior end, initially coiling as seminal
vesicle; vas deferens entering prostate in posterior third;
pallial vas deferens leaving prostate in anterior third,
becoming muscular ejaculatory duct when entering neck;
prostate with ovate cross section; penis simple, usually
tapering more or less continuously from broad base, central
chondroid tissue in middle section occasionally bulging out
to form a flange on right side (probably depending on
contraction of penis), penial tip pointed or with blunt end,
with genital opening through left lappet.
FIGURE 3. Shells (SEM photographs). A–C. Fluviopupa deflexa (A. above Ha’urei; B, C. Mt. Perahu); D, E. F. crassiuscula (above
Ha’urei), D. subadult; F, G. F. raivaveensis n. sp.; H, I. F. tubuaia n. sp.; J, K. F. rurutua n. sp., J. female, K. male. Scale bar = 1 mm.
Remarks: This description of the genus has only
slightly been modified from that given in Haase et al. (2006),
which was based on ten species from Fiji including the type
species F. pupoidea, in order to encompass the broader range
of shell shapes and the higher variability of the distal female
genitalia. The connection between face and outer wing of the
lateral radular tooth is apparently flexible (Fig. 9). As in the
Fijian species (Haase et al. 2006), the membranous part of
the outer wing is easily destroyed during preparation, either
through dissolution or mechanically. Without the membrane
the lateral tooth looks like that in New Zealand (Haase,
submitted) and New Caledonian (Haase and Bouchet 1998)
taxa, in which the membrane may be present, just too fragile
to survive radula preparation. This radular feature as well as
the opercular smear and the fan-shaped caecum suggest a
close relationship of Fluviopupa to the New Zealand
radiation of hydrobioid gastropods (Haase, submitted). The
New Zealand genera Halopyrgus, Potamopyrgus and
Sororipyrgus are in fact most similar to Fluviopupa. The
three New Zealand genera lack the rectal angulation in the
roof of the pallial cavity and their seminal receptacle is
closer to the junction of oviduct and bursal duct (Haase,
submitted). In addition, in the Austral species of Fluviopupa
the penis is blunt in contrast to the pointed penial tip of the
taxa from New Zealand. The blunt penis is shared with many
species of Hemistomia from New Caledonia (Haase and
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Bouchet 1998) and species also attributed to Fluviopupa
from Lord Howe Island (Ponder 1982), though. Of the ten
species from Fiji, only one has a blunt penis and two have a
rectal angulation in the pallial roof (Haase et al. 2006). In
addition, the Austral species are more variable in the position
of the receptaculum seminis and the extent of the albumen
gland into the pallial roof. Whether these subtle differences
between species from Fiji and the Austral Islands are
taxonomically significant on the supraspecific level can only
be determined by a phylogenetic analysis based on genetic
data.
Fluviopupa deflexa (Frauenfeld, 1863)
Figures 2A, B, 3A–C, 4, 5, 7A, 9A, B, 10A, B, 11A, B,
12A–D, 13A–C.
Synonymy
Lithoglyphus deflexa Frauenfeld, 1863: 198.
Fluviopupa rapaensis Hubendick, 1952: 292, figs 1d, e, g, 3.
Type material: NHMW 103245 (lectotype, here designated);
NHMW 103247 (2 paralectotypes).
Type locality: Rapa as ‘Island of Opara’ (Frauenfeld
1863: 197).
Additional material: Titikaveka, Rapa, 2 ex. BPBM
140468, syntypes of F. rapaensis; Titikaveka, Rapa, 1 ex.
BPBM 140469, syntype of F. rapaensis; Rp06, stream above
Ha’urei, 60 m asl, Rapa, 27°37.5’ S, 144°20.2’ W [MNHN
(38)]*; Rp24, stream east of first peak on ridge NE of Mt.
Namuere, 180 m asl, Rapa, 27°35.6’ S, 144°21.7’ W
[MNHN (> 50)]*; Rp25, stream on east slope of Mt. Perahu,
80 m asl, Rapa, 27°35.8’ S, 144°21.4’ W [MNHN (8)];
Rp27, stream in hollow N of summit of Mt. Perahu, 530 m
asl, Rapa, 27°35.6’ S, 144°22.4’ W [MNHN (3), coll. R. E
nglund]; Rp34, trickle over overhanging rock face in Baie
Puoro, 10 m asl, Rapa, 27°35.5’ S, 144°22.8’ W [MNHN
(6)]; Rp41, stream above Ha’urei, 50 m asl, Rapa, 27°37.4’
S, 144°20.2’ W [MNHN (27)]; Rp46, stream flowing into
Baie Hiri, 30 m asl, Rapa, 27°37.1’ S, 144°21.0’ W [MNHN
(6)]; Stn75, stream flowing into Baie Anarua, ca. 5 m asl,
Rapa, 27°36.3’ S, 144°22.5’ W [MNHN (> 100), coll. PL];
Stn96, stream flowing into Baie de Ha’urei at Ranagarua, ca.
20 m asl, Rapa, 27°36.3’ S, 144°21.0’ W [MNHN (> 100),
coll. PL].
Habitat and distribution: in springs and streams on
volcanic substrate throughout Rapa; altitudinal range:
10–530 m asl.
Description
Shell (Figs 2A, B, 3A–C, 4, 5, 7A): light brown, dull,
conical, 1.6 times higher than wide, whorls little convex;
protoconch comprising 0.8–1 whorls; aperture broadly ovatepyriform, prosocline, simple varix behind outer lip.
Dimensions given in Table 1.
TABLE 1. Shell morphometry and sex ratio. ah, aperture height; aw, aperture width; bww, width of body whorl (= penultimate whorl); cv,
coefficient of variation adjusted for sample size; f, females; Loc, locality; m, males; N, number of specimens; max, maximum; min,
minimum; sd, standard deviation; Sex rat, sex ratio; sh, shell height; sw, shell width; w, number of whorls; measurements in mm.
Species/Loc/N/Sex rat
F. deflexa
sh
sw
ah
aw
bww
sh/sw
sh/ah
sw/aw
sw/bww
w
lectotype
2.50
1.71
1.29
1.09
1.27
1.47
1.94
1.56
1.34
3.875
Rapa
median
2.42
1.71
1.29
1.11
1.27
1.43
1.85
1.50
1.34
3.875
N=3
mean
2.43
1.73
1.32
1.14
1.28
1.41
1.85
1.52
1.35
3.875
max
2.50
1.81
1.37
1.21
1.31
1.47
1.94
1.56
1.38
3.875
min
2.38
1.67
1.29
1.09
1.25
1.34
1.77
1.49
1.33
3.875
sd
0.06
0.07
0.05
0.06
0.03
0.06
0.09
0.04
0.02
0.000
cv
2.70
4.49
3.77
6.07
2.57
4.91
4.99
2.81
1.91
0.000
median
3.06
1.88
1.33
1.25
1.57
1.63
2.34
1.52
1.20
4.500
Syntypes of F. rapaensis
mean
2.89
1.84
1.33
1.21
1.49
1.56
2.17
1.52
1.24
4.375
Titikaveka
max
3.25
1.98
1.39
1.27
1.65
1.64
2.40
1.58
1.33
4.625
N=3
min
2.37
1.67
1.27
1.10
1.25
1.42
1.78
1.48
1.20
4.000
sd
0.46
0.16
0.06
0.10
0.21
0.12
0.34
0.05
0.07
0.331
cv
17.34
9.43
4.78
8.67
15.09
8.45
17.04
3.62
6.39
8.189
median
2.77
1.71
1.29
1.11
1.40
1.61
2.09
1.52
1.22
4.125
mean
2.70
1.68
1.29
1.11
1.37
1.61
2.10
1.52
1.22
4.069
max
3.16
1.88
1.47
1.25
1.53
1.74
2.35
1.58
1.30
4.625
min
2.27
1.45
1.08
0.94
1.18
1.47
1.83
1.39
1.17
3.375
0.05
0.04
0.294
F. deflexa
F. deflexa
Ha’urei
sd
0.26
0.13
0.10
0.09
0.11
0.06
0.12
cv
9.64
7.75
8.24
8.11
8.33
3.97
6.01
3.17
3.05
7.311
......continued on the next page
150
TABLE 1 (continued)
sh
sw
ah
aw
bww
sh/sw
sh/ah
sw/aw
sw/bww
w
median
2.82
1.77
1.36
1.18
1.38
1.57
2.07
1.51
1.29
4.063
NE of Mt. Namuere
mean
2.80
1.78
1.35
1.18
1.39
1.57
2.08
1.51
1.29
4.025
N = 10
max
2.88
1.86
1.41
1.27
1.45
1.63
2.26
1.61
1.32
4.125
2f/8m
min
2.69
1.72
1.27
1.10
1.33
1.52
2.00
1.44
1.22
3.875
sd
0.07
0.05
0.04
0.04
0.03
0.04
0.07
0.05
0.03
0.115
cv
2.69
2.60
3.32
3.85
2.54
2.59
3.59
3.49
2.26
2.925
F. deflexa
median
2.86
1.78
1.32
1.18
1.49
1.63
2.24
1.51
1.19
4.000
Mt. Perahu
mean
2.89
1.78
1.31
1.18
1.50
1.62
2.20
1.51
1.19
4.031
N = 20
max
3.16
1.88
1.39
1.27
1.61
1.73
2.37
1.58
1.28
4.250
6f/5m
min
2.72
1.67
1.22
1.14
1.41
1.51
2.03
1.44
1.15
3.875
sd
0.14
0.07
0.05
0.04
0.05
0.06
0.10
0.04
0.04
0.127
cv
4.88
3.74
3.65
3.63
3.25
3.84
4.78
2.98
3.17
3.201
F. deflexa
median
3.15
1.87
1.41
1.23
1.62
1.66
2.28
1.53
1.16
4.313
Ranagarua
mean
3.15
1.88
1.39
1.23
1.62
1.68
2.27
1.53
1.16
4.354
N = 18
max
3.72
2.27
1.65
1.49
1.88
1.89
2.40
1.58
1.21
5.000
min
2.29
1.47
1.08
0.98
1.29
1.56
2.13
1.48
1.09
3.750
sd
0.45
0.24
0.17
0.15
0.19
0.07
0.09
0.03
0.03
0.352
cv
14.45
12.74
12.06
12.30
11.88
4.51
3.92
1.83
2.53
8.187
median
2.28
1.54
1.09
0.94
1.22
1.56
2.15
1.57
1.22
4.000
Baie Anarua
mean
2.55
1.61
1.18
1.03
1.34
1.57
2.14
1.56
1.21
4.094
N = 20
max
3.85
2.26
1.67
1.49
1.95
1.88
2.37
1.64
1.31
4.875
min
1.67
1.13
0.81
0.73
0.91
1.40
1.91
1.40
1.05
3.500
sd
0.73
0.37
0.29
0.26
0.35
0.11
0.11
0.06
0.06
0.425
cv
28.76
23.10
24.52
25.86
26.21
7.07
5.09
4.08
5.33
10.514
lectotype
2.98
2.30
1.67
1.59
1.71
1.29
1.79
1.45
1.35
3.875
Rapa
median
2.99
2.33
1.59
1.59
1.71
1.28
1.84
1.49
1.37
3.688
N=4
mean
2.91
2.36
1.59
1.58
1.71
1.24
1.83
1.49
1.38
3.656
max
3.04
2.46
1.67
1.65
1.73
1.32
1.91
1.53
1.44
3.875
F. deflexa
F. deflexa
F. crassiuscula
min
2.64
2.30
1.51
1.51
1.71
1.07
1.75
1.45
1.33
3.375
sd
0.18
0.07
0.06
0.06
0.01
0.11
0.08
0.03
0.05
0.213
cv
6.70
3.38
4.34
3.83
0.62
9.64
4.54
2.23
3.71
6.204
2.59
2.23
1.51
1.45
1.65
1.16
1.71
1.54
1.36
3.375
2.43
2.04
1.31
1.33
1.59
1.18
1.82
1.53
1.31
3.250
F. crassiuscula
Syntype of F. obtusa
Titikaveka
F. crassiuscula
median
Ha’urei
mean
2.43
2.06
1.35
1.35
1.57
1.18
1.80
1.53
1.31
3.233
N = 15
max
2.63
2.35
1.69
1.55
1.71
1.24
2.00
1.62
1.41
3.500
7f/8m
min
2.20
1.80
1.20
1.23
1.39
1.12
1.56
1.44
1.25
2.875
F. crassiuscula
Ha’urei
sd
0.14
0.13
0.14
0.08
0.08
0.03
0.11
0.05
0.04
0.194
cv
5.99
6.52
10.46
6.28
5.41
2.86
5.95
3.06
3.01
6.101
median
3.12
2.27
1.69
1.57
1.72
1.37
1.85
1.51
1.33
4.000
mean
3.12
2.29
1.68
1.54
1.73
1.36
1.86
1.49
1.32
3.800
......continued on the next page
151
TABLE 1 (continued)
sh
sw
ah
aw
bww
sh/sw
sh/ah
sw/aw
sw/bww
w
N=5
max
3.19
2.39
1.74
1.57
1.80
1.41
1.95
1.56
1.34
4.000
3f/2m
min
3.06
2.20
1.57
1.45
1.69
1.30
1.78
1.40
1.30
3.375
sd
0.05
0.09
0.07
0.05
0.05
0.04
0.07
0.07
0.02
0.288
cv
1.78
3.91
4.30
3.49
3.10
3.16
3.94
4.74
1.21
7.952
F. crassiuscula
2.10
1.80
1.22
1.06
1.29
1.16
1.73
1.70
1.39
3.125
Mt. Perahu
2.21
2.00
1.39
1.25
1.37
1.11
1.59
1.59
1.46
3.125
F. raivavaeensis
holotype
2.29
1.33
0.99
0.91
1.14
1.72
2.31
1.46
1.17
4.000
SW Mt. Maunanui pass
median
2.29
1.26
0.93
0.89
1.13
1.80
2.44
1.41
1.12
4.125
N = 20
mean
2.28
1.26
0.93
0.89
1.12
1.81
2.45
1.42
1.13
4.138
7f/13m
max
2.43
1.38
0.99
0.95
1.17
1.92
2.58
1.51
1.25
4.250
min
2.15
1.18
0.87
0.82
1.03
1.72
2.31
1.38
1.07
4.000
sd
0.07
0.05
0.04
0.03
0.04
0.05
0.07
0.03
0.04
0.099
cv
3.07
3.90
3.89
3.47
3.51
3.07
2.76
2.33
3.33
2.411
F. jeanyvesi
holotype
2.10
1.32
0.91
0.81
1.00
1.60
2.31
1.62
1.32
4.000
Anatonu
median
2.10
1.27
0.91
0.81
1.00
1.69
2.31
1.52
1.25
4.000
mean
2.08
1.25
0.90
0.81
0.99
1.67
2.32
1.55
1.27
4.042
max
2.15
1.32
0.91
0.83
1.03
1.71
2.36
1.62
1.32
4.125
min
1.99
1.16
0.87
0.77
0.93
1.60
2.28
1.52
1.24
4.000
sd
0.08
0.08
0.02
0.03
0.05
0.06
0.04
0.06
0.05
0.072
cv
4.41
6.87
2.70
4.71
5.47
4.00
1.99
3.94
3.87
1.934
F. tubuaia
holotype
2.80
1.65
1.23
1.06
1.37
1.70
2.27
1.56
1.20
4.375
SE Mt. Taitaa
median
2.56
1.42
1.05
0.98
1.28
1.75
2.40
1.50
1.14
4.375
N = 20
mean
2.58
1.47
1.08
0.98
1.29
1.76
2.40
1.49
1.14
4.338
8f/8m
max
3.02
1.72
1.25
1.12
1.49
1.93
2.55
1.63
1.20
4.625
min
2.33
1.31
0.98
0.88
1.16
1.66
2.24
1.33
1.06
4.000
sd
0.18
0.12
0.09
0.07
0.09
0.06
0.08
0.06
0.04
0.158
cv
7.07
8.13
8.16
6.72
7.36
3.32
3.25
4.08
3.45
3.679
F. rurutua
holotype
2.31
1.31
1.02
0.90
1.16
1.76
2.27
1.46
1.14
4.125
Te Vaavai valley
median
2.31
1.35
1.02
0.93
1.22
1.74
2.31
1.47
1.13
4.125
mean
2.40
1.38
1.04
0.93
1.22
1.74
2.32
1.48
1.13
4.188
max
2.74
1.53
1.18
1.02
1.33
1.83
2.42
1.54
1.19
4.500
min
2.20
1.25
0.94
0.86
1.14
1.64
2.19
1.42
1.07
4.000
N=3
N = 16f
sd
0.16
0.07
0.07
0.04
0.06
0.06
0.06
0.04
0.03
0.144
cv
6.86
5.50
6.99
4.38
4.85
3.35
2.84
2.62
3.10
3.501
median
2.21
1.27
0.94
0.87
1.10
1.73
2.31
1.47
1.15
4.000
Te Vaavai valley
mean
2.20
1.28
0.96
0.87
1.11
1.72
2.29
1.47
1.15
4.036
N = 24m
max
2.55
1.41
1.06
0.98
1.23
1.88
2.43
1.66
1.24
4.375
min
1.84
1.18
0.86
0.76
0.96
1.44
2.09
1.38
1.09
3.750
sd
0.17
0.06
0.05
0.05
0.06
0.10
0.09
0.06
0.04
0.145
cv
7.65
5.11
5.46
6.22
5.67
5.94
3.97
4.10
3.77
3.630
F. rurutua
Operculum: with white, non-calcareous smear on
attachment area.
External features: some traces of black pigment behind
eyes, on head and foot as well as on roof of mantle cavity.
152
FIGURE 4. Varix of Fluviopupa deflexa (Mt. Perahu), apical views. Scale bars = 100 µm.
FIGURE 5. Fluviopupa deflexa from (Baie Anarua). Scale bar = 1 mm.
Mantle cavity: ctenidium with 16–19 filaments,
abutting directly on pericardium; osphradium behind middle
of ctenidium, reaching up to third of length of ctenidium;
kidney extending into pallial roof; hypobranchial gland not
Digestive system (Figs 9A, B, 10A, B, 11A, B): radular
formula: R: 5 1 5/5 5, L: 5–7 1 6–7, M1: 29–33, M2:
32–39 (above Ha’urei; N = 5), R: 5 1 5/5 5, L: 6–7 1 6–7,
M1: 30–32, M2: 37–41 (NE of Mt. Namuere; N = 4); rectum
making U-shaped loop left of pallial genital glands.
Female genitalia (Fig. 12A–D): ovary sac-shaped,
starting 0.5–0.75 whorls below apex and comprising 0.75
whorls, reaching fan-shaped caecum; proximal loop of renal
oviduct bent towards albumen gland; receptaculum seminis
lying variably against middle part of bursa copulatrix; bursa
copulatrix pyriform, more elongate in population from
Ha’urei, duct entering ventrally or slightly above ventral
edge; proportions of albumen and capsule glands variable,
either can be longer than the other one, at least 1/3 of
albumen gland extending into pallial roof, anterior section of
capsule gland milky-white (in population from NE of Mt.
Namuere third section of capsule gland not differentiated),
central part opaque-white, posterior part intermediate white,
albumen gland milky-white.
Male genitalia (Fig. 13A–C): testis lobate, starting
0.75–1 whorl below apex comprising 0.75–1.5 whorls,
reaching posterior edge of stomach; seminal vesicle leaving
testis 0.25 whorls proximal to anterior end; penis slender,
tapering slightly, tip widening and blunt.
Remarks: The large, broadly-conical shell and the varix
behind the aperture distinguish F. deflexa from the globular
F. crassiuscula [sh/sw (both populations from the dam above
Ha’urei (Table 1), t-test: t38 = -15.769, P < 0.001], which was
always found in sympatry, as well as from the species
occurring on the other Austral islands, which are smaller and
more slender [comparison of sh/sw (Table 1) with F. tubuaia
n. sp., the largest of the non-Rapa species, t-test: t38 = -7.781,
P < 0.001]. The penial morphology is clearly different from
Hubendick’s (1952) description. We suppose that his
drawing is based on a misinterpretation rather than assuming
different species. He has also overlooked the varix behind
the outer lip. F. deflexa is very variable in terms of shell
morphology as well as genital anatomy. Since the variability
seems to be continuous across and partly within populations
[mean sh/sw ranging from 1.41–1.68 or see e.g. the large
coefficients of variation of the shell measurements in the
populations from Ranagarua and the Baie Anarua (Table 1,
Fig. 5)], we do not think that there is more than one species
involved. The high variability of the sample from the Baie
Anarua is especially intriguing. Unlike the sample from
Ranagarua, which was taken from about 1 m2 and therefore
almost certainly represents a single, variable deme, the Baie
Anarua snails were collected along a stretch of more than 10
m (P. Lozouet, pers. comm.) and therefore probably across
several demes considering the low vagility of the snails and
the weak current of the stream. High and continuous
variation of shell morphology has also been found in
Potamopyrgus antipodarum (Gray, 1843) along two hill
country streams in New Zealand. The clinal variation was
correlated with flow, but may also or alternatively have been
caused by a gradient in nutrients (Haase 2003). The size
distribution along the stream in the Baie Anarua is
unfortunately not known. However, since the physical
properties of the stream did not appear to vary along the
stretch sampled (P. Lozouet, pers. comm.), this case does
probably not parallel the situation in New Zealand and may
therefore have different causes.
Fluviopupa crassiuscula (Frauenfeld, 1863)
Figures 2C, D, 3D, E, 6, 7B, 9C, 10C, 12E–G, 13D.
Synonymy
Lithoglyphus crassiuscula Frauenfeld, 1863: 197
Fluviopupa obtusa Hubendick, 1952: 293, figs 1f, 4.
Type material: NHMW 103246 (lectotype, here designated);
NHMW 103248 (3 paralectotypes).
153
FIGURE 6. Fluviopupa crassiuscula (Baie Anarua). Arrows
indicate extent of thickened outer lip. Scale bar = 1 mm.
Type locality: Rapa as ‘Island of Opara’ (Frauenfeld
1863: 197).
Additional material: Titikaveka, Rapa, 1 ex. BPBM
140476, syntype of F. obtusa; Rp06, stream above Ha’urei,
60 m asl, Rapa, 27°37.5’ S, 144°20.2’ W [MNHN (> 50)]*;
Rp14, moss in bush on ridge under summit of Mt. Namuere,
580 m asl, Rapa, 27°35.7’ S, 144°22.1’ W [MNHN (1)];
Rp24, stream east of first peak on ridge NE of Mt. Namuere,
180 m asl, Rapa, 27°35.6’ S, 144°21.7’ W [MNHN (> 100)];
Rp25, stream on east slope of Mt. Perahu, 80 m asl, Rapa,
27°35.8’ S, 144°21.4’ W [MNHN (54)]; Rp27, stream in
hollow N of summit of Mt. Perahu, 530 m asl, Rapa,
27°35.6’ S, 144°22.4’ W [MNHN (3), coll. R. Englund];
Rp34, trickle over overhanging rock face in Baie Puoro, 10
m asl, Rapa, 27°35.5’ S, 144°22.8’ W [MNHN (1)]; Rp37,
stream flowing into Baie Pariati, 15 m asl, Rapa, 27°34.9’ S,
144°21.7’ W [MNHN (22)]; Rp41, stream above Ha’urei, 50
m asl, Rapa, 27°37.4’ S, 144°20.2’ W [MNHN (26)]; Rp46,
stream flowing into Baie Hiri, 30 m asl, Rapa, 27°37.1’ S,
144°21.0’ W [MNHN (> 100)]; Stn75, stream flowing into
Baie Anarua, ca. 5 m asl, Rapa, 27°36.3’ S, 144°22.5’ W
[MNHN (> 100), coll. PL]; Stn89, swamp, Pointe
Pukitarava, 2 m asl, Rapa, 27°35.9’ S, 144°18.5’ W [MNHN
(1), coll. PL]; Stn96, stream flowing into Baie de Ha’urei at
Ranagarua, ca. 20 m asl, Rapa, 27°36.3’ S, 144°21.0’ W
[MNHN (> 100), coll. PL].
154
Habitat and distribution: in springs and streams on
volcanic substrate throughout Rapa; altitudinal range: 2–530
m asl.
Description
Shell (Figs 2C, D, 3F, G, 6, 7B): light brown, dull,
globular, about 1.1–1.2, rarely 1.4 times higher than wide,
whorls convex; protoconch comprising 0.8–1 whorls;
aperture broadly ovate, prosocline, occasionally with
posterior angle, in large and massive shells from Baia
Anarua the outer lip may be partly thickened. Dimensions
given in Table 1.
FIGURE 7. Protoconch. A. Fluviopupa deflexa (above Ha’urei); B. F. crassiuscula (above Ha’urei); C. F. raivavaeensis n. sp.; D. F.
tubuaia n. sp.; E. F. rurutua n. sp. Scale bars = 100 µm.
FIGURE 8. Operculum. Fluviopupa tubuaia n. sp. A. outside; B. inside. Scale bar = 100 µm.
155
FIGURE 9. Radula. A, B. Fluviopupa deflexa (above Ha’urei); C. F. crassiuscula (above Ha’urei); D–F. F. tubuaia n. sp.; G, H. F. rurutua
n. sp. Arrows indicate elastic, membranous neck region of lateral teeth; membrane dissolved in E, F. Scale bars = 10 µm.
156
FIGURE 10. Stomach. A, B. Fluviopupa deflexa (same specimen, above Ha’urei); C. F. crassiuscula (above Ha’urei); D. F. raivavaeensis
n. sp.; E. F. tubuaia n. sp. Abbreviations: dg, opening into digestive gland; fc, fan-shaped caecum; in, intestine; os, oesophagus; ss, style
sac. Scale bar = 200 µm.
FIGURE 11. Course of rectum. A, B. Fluviopupa deflexa (A. female, Mt. Perahu; B. male, above Ha’urei); C, D. F. raivavaeensis n. sp.
(C. female; D. male); E. F. rurutua n. sp. (male). Abbreviations: fp, fecal pellet; po, pallial oviduct; pr, prostate; r, rectum; ss, style sac.
Scale bar = 200 µm.
157
FIGURE 12. Distal female genitalia. A–D. Fluviopupa deflexa (A, Mt. Perahu; B, C. NE of Mt. Namuere; D. above Ha’urei); E–G. F.
crassiuscula (above Ha’urei); H–J. F. raivavaeensis n. sp.; K–N. F. tubuaia n. sp.; O, P. F. rurutua n. sp. Lines connect different aspects or
details of same individual. Abbreviations: acg, anterior capsule gland; ag, albumen gland; bc, bursa copulatrix; bd, bursal duct; go, genital
opening; od, oviduct; pcg, posterior capsule gland; rs, receptaculum seminis; vc, ventral channel. Scale bar = 200 µm.
158
FIGURE 13. Penis. A–C. Fluviopupa deflexa (A. NE of Mt. Namuere; B, C. Mt. Perahu), C enlargement of B showing sperm in front of
genital opening; D. F. crassiuscula (above Ha’urei); E. F. raivavaeensis n. sp.; F. F. jeanyvesi n. sp.; G. F. tubuaia n. sp.; H. F. rurutua n. sp.
Scale bars = 100 µm, in C 10 µm.
159
attachment area.
External features: mantle black except for areas over pallial
genital glands and areas not facing exterior.
kidney extending into pallial roof; hypobranchial gland not
Digestive system (Figs 9C, 10C): radular formula: R:
4–5 1 4–5/3–4 3–4, L: 3–4 1 3, M1: 11–13, M2: 20–24;
rectum close to pallial oviduct in females, but making Ushaped loop left of prostate in males.
Female genitalia (Fig. 12E–G): ovary sac-shaped,
starting 0.5 whorls below apex, comprising up to 0.5 whorls,
reaching fan-shaped caecum, rarely posterior edge of
stomach; renal oviduct without any special features; position
of receptaculum seminis variable, from anterior edge of
bursa copulatrix to middle part; bursa copulatrix elongatepyriform, duct entering ventrally or slightly above ventral
edge; length of albumen gland about 1/3 of capsule gland,
albumen gland hardly reaching into pallial roof, anterior
section of capsule gland milky-white, central one yellow,
posterior one white, albumen gland milky-white.
Male genitalia (Fig. 13D): testis lobate, starting
0.25–0.5 whorls below apex, comprising 0.75–1.125 whorls,
overlapping posterior chamber of stomach; seminal vesicle
leaving testis 0.25–0.33 whorls proximal to anterior end;
penis tapering until about the middle, then margins remain
parallel, tip blunt.
Remarks
Fluviopupa crassiuscula is the only globular species in
the Austral Islands. For comparison with the mostly
sympatric F. deflexa see Remarks under the latter species.
The sample from Ha’urei contained five specimens that were
much more slender than the rest. However, no difference in
their anatomy was found. They were possibly washed to the
sampling site from a different population. In general, the
variability in shell size and shape is considerable. A single
shell still containing the animal was found in moss in the
bush on the ridge under the summit of Mt. Namuere (station
Rp41), a location with no water body, not even a dry
streambed. If this finding is not the result of accidental
contamination, it suggests the possibility of arial
transportation by a bird or insect.
Frauenfeld’s (1863) names Lithoglyphus crassiuscula
and L. deflexa do not meet both criteria for nomina oblita
(forgotten names), although he appears to have remained the
only author to subsequently use these names (Frauenfeld
1865). We are not aware of any use of these names after
1899, which would fulfil one of the conditions for
recognition as forgotten names (ICZN 1999: Art. 23.9.1.1).
However, the junior synonyms of Hubendick (1952) were
definitely not used “in at least 25 works, published by at least
10 authors in the immediately preceding 50 years and
encompassing a span of not less than 10 years” (ICZN 1999:
Art. 23.9.1.2). Therefore we use Frauenfeld’s names for the
two species of Fluviopupa occurring on Rapa.
Fluviopupa raivavaeensis n. sp.
Figures 2E, 3F, G, 7C, 10D, 11C, D, 12H–J, 13E.
Type material: holotype MNHN 4403, paratypes MNHN
4404 (> 100)*, AMS C. 205315 (10).
Type locality: Rv65, stream in hollow SW of pass
between Mt. Maunanui and Mt. Raraterepa, 105 m asl,
Raivavae, 23°52.0’ S, 147°39.9’ W.
Etymology: The name of the new species is derived
from Raivavae, the island to which it is endemic.
Additional material: Rv23, stream in hollow on N slope
of Mt. Hiro above Anatonu, 270 m asl, Raivavae, 23°51.4’ S,
147°38.8’ W [MNHN (> 50)]; Rv40, stream above Anatonu,
W of temple, below dam, 40 m asl, Raivavae, 23°51.2’ S,
147°38.7’ W [MNHN (> 100)]; Rv41, stream above
Anatonu, at base of cliff of Mt. Hiro, 100 m asl, Raivavae,
23°51.5’ S, 147°38.9’ W [MNHN (> 8)]; Rv44, stream
above Anatonu, at base of cliff of Mt. Hiro, in forest, 70 m
asl, Raivavae, 23°51.4’ S, 147°38.6’ W [MNHN (> 50)];
Rv70, stream in hollow under pass between Mt. Araua and
Mt. Hiro, on SE slope of Mt. Araua, 210 m asl, Raivavae,
23°51.6’ S, 147°39.3’ W [MNHN (49)].
Habitat and distribution: in streams on volcanic
substrate throughout Raivavae; altitudinal range: 40–270 m
asl.
Description
Shell (Figs 2E, 3F, G, 7C): light brown, transparent,
conical, about 1.8 times higher than wide, whorls moderately
convex; protoconch comprising 0.9 whorls; aperture ovatepyriform, orthocline. Dimensions given in Table 1.
attachment area.
External features: black stripes behind eyes, traces of
black pigment on pallial roof, narrow, central band of black
pigment on visceral sack.
kidney extending only occasionally into pallial roof; small
hypobranchial gland in rear of mantle cavity reaching about
3rd gill filament.
Digestive system (Figs 10D, 11C, D): radular formula:
R: 4–5 1 4–5/3–4 3–4, L: 4–5 1 5–6, M1: 25–28, M2:
31–36; rectum close to pallial oviduct in females, but making
U-shaped loop left of prostate in males.
Female genitalia (Fig. 12H–J): ovary sac-shaped,
starting 1.25–2 whorls below apex, comprising up to 0.5
whorls, not reaching fan-shaped caecum; renal oviduct
without any special features; receptaculum seminis pyriform
to elongate, lying against anterior third of bursa copulatrix;
bursa copulatrix short-pyriform, duct entering ventrally or
slightly above ventral edge, occasionally close to the middle
of bursa; length of albumen gland 1/3–1/2 capsule gland,
about 1/2 of albumen gland extending into pallial roof,
anterior section of capsule gland milky-white, posterior one
opaque white, albumen gland milky-white.
160
Male genitalia (Fig. 13E): testis lobate, starting 1–1.25
whorls below apex, comprising 1–1.25 whorls, slightly
overlapping posterior chamber of stomach; seminal vesicle
leaving testis 0.25 whorls proximal to anterior end; penis
hardly tapering with practically parallel margins, tip blunt,
left lappet extended to papilla with genital opening.
Remarks
Morphologically, F. raivavaeensis n. sp. is most similar
to F. rurutua n. sp. Both females and males of the latter are
relatively wider [sh/sw (Table 1), ANOVA: F2,61 = 9.441, P <
0.001; in both interspecific Tukey’s pairwise posthoc
comparisons P < 0.005; the sexes of F. rurutua n. sp. are not
distinguishable in shape (see also below)]. In addition, F.
raivavaeensis n. sp. has the broadest penis with parallel
margins within the genus and is the only species with a
small, but distinct hypobranchial gland.
Fluviopupa jeanyvesi n. sp.
Figures 2F, 13F.
4406 (2)*.
Type locality: Rv41, stream above Anatonu, at the base
of cliff of Mt. Hiro, 100 m asl, Raivavae, 23°51.5’ S,
147°38.9’ W.
Etymology: This species is dedicated to Jean-Yves
Meyer in recognition for his efforts for the conservation of
the biota of French Polynesia. He was the leader of the three
expeditions to the Austral Islands, during which the snails
described in this paper were collected.
Habitat and distribution: only known from the type
locality.
Description
Shell (Fig. 2F): light brown, transparent, conical, about
1.65 times higher than wide, whorls moderately convex; no
protoconch data available; aperture ovate-pyriform,
orthocline.
Operculum: white, non-calcareous smear on attachment
area very small or lacking. Dimensions given in Table 1.
External features: exposed parts of mantle black, except
area over prostate and head from eyes backward, which are
more or less unpigmented.
Mantle cavity (N = 1): ctenidium with 15 filaments,
abutting directly on pericardium; osphradium slightly behind
middle of ctenidium, reaching up to third of length of
ctenidium; kidney extending into pallial roof; hypobranchial
gland not apparent in dissections.
Digestive system (N = 1): no radula data available;
rectum making U-shaped loop left of prostate in males.
Female genitalia: no data available.
Male genitalia (Fig. 13F; N = 1): testis lobate, starting
0.75 whorls below apex, comprising 1.125 whorls,
overlapping fan-shaped caecum reaching posterior edge of
stomach; seminal vesicle leaving testis 0.25 whorls proximal
to anterior end; penis tapering from broad base getting fairly
slender, but tip blunt.
Remarks
Fluviopupa jeanyvesi n. sp. is the smallest of the
conical species from the Austral Islands. It is relatively wider
but has a narrower spire and a much thinner and longer penis
than its sympatric congener F. raivavaeensis n. sp. Males of
F. rurutua n. sp. are comparable in shape (sh/sw) and penial
morphology, but have a larger aperture and wider spire.
Because we have only data of three shells we refrained from
statistical comparisons. The anatomical data are based on the
investigation of a single male.
Fluviopupa tubuaia n. sp.
Figures 2G, 3H, I, 7D, 8, 9D–F, 10E, 12K–N, 13G.
4408 (> 50)*, AMS C.205316 (5).
Type locality: Tb21a, stream SE of Mt. Taitaa, 45 m asl,
Tubuai, 23°22.5’ S, 149°27.6’ W.
from Tubuai, the island to which it is endemic.
Habitat and distribution: only known from type locality.
Description
Shell (Figs 2G, 3H, I, 7D): brown, transparent, conical,
about 1.75 times higher than wide, whorls moderately
convex; protoconch comprising 0.9–1 whorl; aperture ovatepyriform, orthocline, slightly angled posteriorly. Dimensions
given in Table 1.
Operculum (Fig. 8): with white, non-calcareous smear
on attachment area.
External features: tentacles in front of eyes grey, black
stripes behind eyes, pallial roof black except area over pallial
genital glands, narrow, central band of black pigment on
visceral sack.
abutting directly on pericardium; osphradium entirely behind
middle of ctenidium, quarter of length of ctenidium; kidney
extending into pallial roof; hypobranchial gland not apparent
in dissections.
Digestive system (Figs 9D–F, 10E): radular formula: R:
5–6 1 5–6/3–4 3–4, L: 4–5 1 5, M1: 24–28, M2: 30–39;
rectum close to pallial oviduct in females, but making
angulation at prostate in males.
Female genitalia (Fig. 12K–N): ovary lobate, starting
1–1.5 whorls below apex and comprising up to 1 whorl, not
reaching fan-shaped caecum; proximal loop of renal oviduct
bent towards albumen gland; receptaculum seminis lying
against middle part of elongate bursa copulatrix with duct
entering ventrally; albumen and capsule glands about equally
long, 1/3 of albumen gland extending into pallial roof,
anterior section of capsule gland milky-white, posterior one
opaque-white, albumen gland milky-white.
Male genitalia (Fig. 13G): testis lobate, starting 1–1.25
whorls below apex comprising 1–1.25 whorls, reaching
posterior edge of stomach; seminal vesicle leaving testis
0.125 whorls proximal to anterior end; penis slender,
tapering slightly, tip widening and blunt.
161
Remarks
Fluviopupa tubuaia sp.nov. is more slender than F.
deflexa (see under respective Remarks above). In addition, it
lacks the varix behind the aperture, is extensively pigmented,
has more gill filaments and a longer bursa copulatrix than the
species from Rapa.
albumen gland milky-white.
Male genitalia (Fig. 13H): testis lobate, starting 1–1.25
whorl below apex comprising 0.75–1.125 whorls, slightly
overlapping proximal chamber of stomach; seminal vesicle
leaving testis 0.125–0.25 whorls proximal to anterior end;
penis slender, tapering slightly, tip blunt.
Fluviopupa rurutua n. sp.
Figures 2H, 3J, K, 7E, 9G, H, 11E, 12O, P, 13H.
Remarks
Fluviopupa rurutua n. sp. differs from all its congeners
by its sexual size dimorphism and from most congeners by
the insertion of the bursal duct close to the middle of the
bursa copulatrix. Only in F. raivavaeensis n. sp. does the
bursal duct insert in a similar position. F. raivavaeensis n. sp.
is also the morphologically most similar species. However, F.
rurutua is wider (see Remarks under F. raivavaeensis n. sp.).
In addition, F. rurutua n. sp. lacks both opercular smear and
hypobranchial gland in contrast to F. raivavaeensis n. sp.
Hubendick (1952) did not recognize the differences between
F. deflexa and the species from Rurutu and consequently did
not distinguish them taxonomically.
4410 (> 50)*, AMS C.205317 (5).
Type locality: Rr59, stream in Te Vaavai valley, 45 m
asl, Rurutu, 22°26.3’ S, 151°22.2’ W.
from Rurutu, the island to which it is endemic.
Additional material: Rr09, stream Peva Iti on S side of
Mato Arei, 10 m asl, Rurutu, 22°27.9’ S, 151°19.7’ W
[MNHN (7)]; Rr15, valley of Ruahoina E Mt. Teape, 170 m
asl, Rurutu, 22°27.8’ S, 151°22.0’ W [MNHN (> 100)];
Rr26b, stream Turiarata S Avera, 80 m asl, Rurutu, 22°29.2’
S, 151°10.9’ W [MNHN (2)]; Rr70, under Puputa stream
waterfall, 80 m asl, Rurutu, 22°27.0’ S, 151°21.1’ W
[MNHN (1), coll. R. Englund].
Habitat and distribution: in springs and streams
throughout Rurutu; altitudinal range: 10–170 m asl.
Description
Shell (Figs 2H, 3J, K, 7E): brown, transparent, conical,
about 1.75 times higher than wide, whorls moderately
convex; protoconch comprising 0.8–1 whorl; distinct sexual
size dimorphism with males significantly smaller than
females (shell height, t-test: t38 = -3.807, P < 0.001); aperture
ovate-pyriform, orthocline. Dimensions given in Table 1.
Operculum: without smear on attachment area.
External features: tentacles without pigment, head
black behind eyes, pallial roof black except area over pallial
genital glands, visceral sack largely pigmented.
of ctenidium, reaching third of length of ctenidium; kidney
not extending into pallial roof; hypobranchial gland not
Digestive system (Figs 9G, H, 11E): radular formula (N
= 4): R: 5–6 1 5–6/3 3, L: 5 1 5–6, M1: 23–25, M2: 34–38;
rectum close to pallial oviduct in females, but making Ushaped loop left of prostate in males.
Female genitalia (Fig. 12O, P): ovary lobate, starting
1.25–1.5 whorls below apex and comprising up to 1 whorl,
slightly overlapping proximal chamber of stomach; proximal
loop of renal oviduct bent towards albumen gland;
receptaculum seminis lying against middle part of bursa
copulatrix, eventually reaching dorsal edge; bursa copulatrix
pyriform, duct entering slightly above ventral edge; capsule
gland slightly longer than albumen gland, albumen gland
almost entirely behind pallial cavity, anterior section of
capsule gland milky-white, posterior one opaque-white,
Discussion
Relationships and biogeography
The hydrobioids from the Austral Islands do not have a
synapomorphy distinguishing them from the species of
Fluviopupa occurring in Fiji and are therefore clearly
congeneric. Even the blunt or bilobed penis characterising all
six Austral species is present in one of the ten known Fijian
species (Haase et al. 2006). This suggests that this Fijian and
the Austral species share a common ancestor. However, blunt
or bilobed penes are also present in species from Lord Howe
Island (Ponder 1982) and in several species of Hemistomia
Crosse, 1872 (Haase and Bouchet 1998) indicating that this
character may be subject to convergent evolution.
Nevertheless, considering the similarity of the Austral and
Fijian species, as well as the geographic distances, it is safe
to assume that the ancestor of the Austral species was
derived from Fiji and most likely was a freshwater species,
since today no marine or brackish water hydrobioids are
known from either archipelago. The only brackish water
hydrobioids of the Southwest Pacific occur in Australia and
New Zealand (e.g. Ponder and Clark 1988, Ponder et al.
1991; Winterbourn 1970; Haase submitted). Of the island
groups lying between Fiji and the Austral Islands only
Mangaia and some sea mounts belonging to the Cook Islands
are older than 10 Myr (Kroenke 1996; Bonneville et al.
2002). Eua, which detached from New Caledonia in the
Eocene, reached its present position in the Tonga
archipelago, which originated about 10 Mya, only in the late
Miocene. The Samoan island chain is even younger
(Kroenke 1996). In contrast, the oldest parts of Viti Levu, the
main island of Fiji, were formed 40 Mya and Rimatara, the
oldest island of the Australs, is 27 Myr old (Kroenke 1996;
Bonneville et al. 2002). This suggests that the Austral
Islands were directly colonised from Fiji, possibly already in
the late Oligocene or early Miocene, provided that the
162
absence of hydrobioids from Tonga, Samoa (Cowie 1998)
and the younger Cook Islands (Cook Islands Biodiversity
Database 2004) is not due to recent extinction. Only
Mangaia, today strongly eroded and almost bare of natural
vegetation, may have served as stepping stone. This
hypothesis would be testable with molecular data. If
confirmed, Fluviopupa would represent another remarkable
example of morphostasis among hydrobioid gastropods (see
e.g., Clark et al. 2003; Wilke 2003; Haase submitted).
The Austral Islands were largely formed by the periodic
activity of two volcanic hot spots. The age of the oldest parts
of each island increases from east to west (Fig. 1; Bonneville
et al. 2002). Given the west-east direction of the island chain,
colonisation of the single islands has probably occurred in
this direction. This would again be testable by a phylogenetic
analysis base on sequence data. If the ancestor of the Austral
species of Fluviopupa arrived early as hypothesised above,
genetic distances between F. rurutua and the species from
Rapa should be considerable. The material this paper is
based on has been fixed in ethanol. Unfortunately, only few
samples of the largest and probably most robust species F.
crassiuscula and F. deflexa were suitable for DNA extraction
and sequencing (MH, unpubl. data), so that we were not able
to address these questions here.
Conservation
No hydrobioids were found on Rimatara, the westernmost and oldest of the Austral Islands, during the 2004
expedition. Rimatara is the smallest and least elevated, i.e.
most eroded island of the archipelago, but has the highest
population density (ITSTAT 1996). Natural vegetation has
almost completely disappeared and potentially suitable
freshwater habitats have been greatly modified. Except for
the occasional dripping of rusty water from pipes thrust into
seepages, no running water was encountered in 2004.
Sediments collected in dry streambeds did not contain
hydrobioids. If they were ever present, they have become
extinct, probably as a consequence of human land
transformation. Because of this uncertainty it is impossible to
infer whether Rimatara was the first of Austral Islands to be
colonised by Fluviopupa.
The mollusc survey conducted on the Austral Islands
between 2002 and 2004 covered most of the area. Not all
freshwater habitats could be investigated, although as many
as possible were. The sampling intensity is sufficient to
determine the actual distribution of the species and to justify
an assessment of threat according to IUCN (2001) criteria.
Four species qualify as Vulnerable meeting criterion D2
(area of occupancy very restricted, typically less than 20
km2). Fluviopupa jeanyvesi and F. tubuaia must be
considered Critically Endangered. Each is known from only
a single locality and occupying less than 10 km2. The area
where F. jeanyvesi has been collected once harboured a rich,
locally endemic fauna including five now extinct species of
Endodontidae (Solem 1976; OG and BF, unpubl. data)
suggesting that this part of Raivavae has a peculiar history in
terms of zoogeography. This small area lies between the
coast and the cliffs of the central mountain chain and is under
considerable pressure from human settlement. Tubuai is the
most degraded island after Rimatara with the highest
population density (ITSTAT 1996) and hardly any natural
vegetation left (Meyer 2004), so that a decline of suitable
habitat must be feared as well [criteria B2ab(ii, iii)]. Without
protective action F. jeanyvesi and F. tubuaia may soon share
the fate of its hypothetical relative from Rimatara (see
above).
Lack of suitable habitat or habitat destruction are
certainly not responsible for the complete absence of
hydrobioid gastropods from other Polynesian islands. Long
distance transportation across wide stretches of open ocean is
apparently a rare event. The simplest explanation may be the
young age of most islands. There may not have been enough
time for such a chance event to have occurred. It is still
intriguing that all Austral islands except Rimatara harbour
hydrobioids, although the distance between Rurutu and Rapa
is larger than between the former and the Society Islands.
Thus, the distribution of hydrobioids in the Pacific may, to a
large extent, reflect routes of birds, which are the most likely
long distance transport agents (Rees 1965; Vagvolgyi 1976).
The current composition and distribution of the avifauna in
the tropical Pacific is but a pale image of what it used to be
before early Polynesians colonised the Pacific, between
3,500 and 1,000 years BP (Irwin 1992). As many as 2,000
bird species became extinct after humans colonised islands
and most seabird breeding colonies in the mountains were
destroyed (Steadman 1995). It is impossible to know
precisely the intensity and directions of bird movements
between islands in pre-human times, but some extant water
birds including the duck Anas superciliosa and the rail
Porzana tabuensis have a very large range from Australia to
Eastern Polynesia, and the long-tailed cuckoo Eudynamis
taitensis still migrates from New Zealand to Fiji and Eastern
Polynesia. This indicates that west-east bird movement has
occurred for a long time in the region, which may possibly
account for the modern distribution of Fluviopupa in the
Pacific.
Acknowledgements
We thank the Délégation à la recherche of the government of
French Polynesia and the Research Institute Louis Mallardé
(Papeete, Tahiti) for financial support and organizing the
expeditions. We are especially indebted to Priscille Tea
Frogier and Jean-Yves Meyer, representatives of the former
organization, for their extraordinary commitment. Ron
Englund (Bishop Museum, Honolulu), a colleague in the
field, provided some of the samples. We also thank Winston
F. Ponder (AMS) informing us about Frauenfeld’s taxa.
Anita Eschner (NHMW) and Regina Kawamoto (BPBM) are
acknowledged for lending type material and two anonymous
reviewers provided helpful comments.
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the genus Fluviopupa on the Austral Islands

Transcription

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