Molluscan Research
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New species of Epitoniidae (Gastropoda:
Epitonioidea) from the Red Sea
Antonio Bonfitto
To cite this article: Antonio Bonfitto (2018) New species of Epitoniidae (Gastropoda: Epitonioidea)
from the Red Sea, Molluscan Research, 38:2, 119-129, DOI: 10.1080/13235818.2017.1385168
To link to this article: https://doi.org/10.1080/13235818.2017.1385168
Published online: 31 Oct 2017.
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MOLLUSCAN RESEARCH, 2018
VOL. 38, NO. 2, 119–129
https://doi.org/10.1080/13235818.2017.1385168
New species of Epitoniidae (Gastropoda: Epitonioidea) from the Red Sea
Antonio Bonfitto
Department of Biological, Geological and Environmental Sciences (BiGeA), Bologna, Italy
ABSTRACT
ARTICLE HISTORY
Based on material stored in the Zoological Museum of the University of Bologna (MZB), four new
species of epitoniids from the shallow waters of the Red Sea are described: Epitonium
(Laeviscala) yemenita n. sp., Epitonium (Laeviscala) morassii n. sp., Epitonium (Labeoscala)
zabargadense n. sp. and Epitonium (Labeoscala) aranea n. sp. Scanning electron microscope
illustrations of type specimens of Scalaria gracilis Sowerby, 1844, Scalaria fucata Pease, 1861,
Graciliscala histricosa Jousseaume, 1912, Graciliscala rostrata Jousseaume, 1912, Scala
rissoinaeformis Melvill, 1903 and Scala thelcteria Melvill & Standen, 1903 are given. Systematic
remarks on some species belonging to the subgenus Laeviscala are treated in additional
notes. A lectotype of Graciliscala histricosa is designated.
http://zoobank.org/urn:lsid:zoobank.org:pub:8304A24D-5985-43D5-AEBF-1A7ED39A1F1C
Received 4 April 2017
Final version received 25
September 2017
Introduction
The Epitoniidae Berry, 1910 (1812) is a very large family
of Caenogastropoda Cox, 1960 parasites on cnidarian
anthozoans (Robertson 1963; Sabelli and Taviani
1984; Oliverio et al. 1997; Gittenberger et al. 2000; Gittenberger and Gittenberger 2005; Kokshoorn et al.
2007) or free-living micropredators on annelid worms
and nemerteans (Bouchet and Warén 1986). The
family is represented in almost all seas, from lower to
abyssal depths but the greatest number of species is
found especially in tropical waters (Weil et al. 1999).
`More than 700 Recent specific taxa have been
described within this family and many more are still
to be studied and described (Weil et al. 1999; Brown
and Neville 2015). The most important modern contributions to knowledge of the Epitoniidae are those of
Kaicher (1980, 1981, 1983), Kilburn (1985), Bouchet
and Warén (1986), Weil et al. (1999), Gittenberger
et al. (2000), Garcia (2003), Nakayama (2003), Gittenberger and Gittenberger (2005) and Lee and Wu (2012).
The first catalogue of Epitoniidae of the Red Sea was
published by Jousseaume (1912) who cited a total of
61 nominal species based on previous literature and
on original material collected and described by
himself (Jousseaume 1894, 1912). In their preliminary
list of the Red Sea molluscs, based on a large bibliography and unpublished data from various collections, Dekker and Orlin (2000) listed 57 epitoniid
species.
In order to contribute to the knowledge of the molluscan fauna of the Red Sea, from 1978 the National
Research Council (CNR) of Bologna has carried out
several campaigns in that region. Most of the collected
CONTACT Antonio Bonfitto
Bologna, Italy
antonio.bonfitto@unibo.it
Caenogastropoda; Epitonium;
Labeoscala; Laeviscala;
Mollusca; systematic; type
specimens
samples were stored in the Zoological Museum of the
University of Bologna. As a result, a large collection of
molluscs was built up but not completely studied. In
this context, I recently started a revision of all the epitoniid species from the Red Sea stored there. Numerous empty shells belonging to four distinctive new
species of the genus Epitonium Röding, 1798 were
found among this abundant material and are here
described: two are characterised by a cancellate microsculpture of the interstices and can be ascribed to the
subgenus Laeviscala de Boury, 1909, while another two
are distinctive of subgenus Labeoscala de Boury, 1912
because of the non-peaked costae, the thickened
outer lip and the rimate umbilicus.
Methods
Descriptions and measurements are based on shells
oriented spire up with the aperture facing the viewer.
All measurements were made using a Wild M5A stereomicroscope and a 10× ocular micrometer. Scanning
electron microscope (SEM) micrographs were taken
using a Jeol JSM-5200. All SEM micrographs of the
type specimens from MNHN and NHMUK were taken
directly by the author on uncoated specimens. Epitoniid classification follows Kilburn (1985), Weil et al.
(1999) and Nakayama (2003).
Institutional
abbreviations:
AM—Australian
Museum, Sydney, Australia; MNHN—Muséum National
d’Histoire Naturelle, Paris, France; MZB—Museo di
Zoologia dell’Università di Bologna, Bologna, Italy;
NHMUK—Natural History Museum, London; ZMA—
Naturalis Biodiversity Center, Leiden, The Netherlands.
Department of Biological, Geological and Environmental Sciences (BiGeA), via Selmi 3, 40126
© 2017 The Malacological Society of Australasia and the Society for the Study of Molluscan Diversity
Published online 31 Oct 2017
KEYWORDS
120
A. BONFITTO
Taxonomy
tropical western Atlantic. In addition to the new
species here described, five species are present in the
Red Sea: Epitonium (Laeviscala) gracile (Sowerby,
1844); Epitonium (Laeviscala) fucatum (Pease, 1861); Epitonium (Laeviscala) sandwichense (Nyst, 1871); Epitonium (Laeviscala) histricosum (Jousseaume, 1912); and
Epitonium (Laeviscala) rostratum (Jousseaume, 1912).
Epitoniidae Berry, 1910 (1812)
Epitonium Röding, 1798
Type species (s.d. Suter, 1913) Turbo scalaris Linnaeus,
1758
Subgenus Laeviscala de Boury, 1909: 257
Type species (o.d.) Scalaria subauriculata Souverbie
in Souverbie & Montrouzier, 1866 (= Graciliscala de
Boury, 1909; type species [s.d. Iredale, 1936] Scalaria
gracilis Sowerby, 1844)
Epitonium (Laeviscala) yemenita n. sp.
Figure 1A–H
Holotype. Red Sea, off Yemen, 14°46.72′ N, 42°32.82′ E,
76 m depth, on muddy sand (MZB5040, coated).
Paratypes. Red Sea, off Yemen, 14°46.72′ N, 42°32.82′ E,
76 m depth, on muddy sand (MZB50402, 3 spm, 12 frgs;
MNHN-IM-2014-6667, 1 spm; NHMUK, 1 spm;
RMNH.5006732, 1 spm). Red Sea, Egypt, Wadi Gimal,
24°40.31′ N, 35°06.30′ E, 20 m depth (MZB50403, 5 spm).
Diagnosis
Material examined
Shell pyramidal, deep suture, imperforate, umbilicus
narrow, fenestrate, peristome thick, axial ribs thick,
partly or completely reflexed, often weakly or not coronated, intervals with axial and spiral microstriae, more
or less granulose at the intersection, forming a cancellate sculpture.
Type material. See above. Other material. Off Sudan, Sanganeb reef, North Point, 19°44.34′ N, 37°26.52′ E, 15–20 m
depth (MZB50409, 1 spm); off Sudan, 19°42.766′ N, 37°
27.012′ E, 677 m depth, MZB (MZB50410, 4 spm, 11
frgs); Aqaba, 29°31.55′ N, 35°00.22′ E, 15–20 m depth
(MZB50411, 5 spm); Jedda, 21°15.01′ N, 39°07.16′ E, 18–
30 m (MZB50412, 1 spm).
Other abbreviations: b—shell width; b/l—ratio of
shell breadth to total shell length; frgs—fragments;
l—shell length; spm—dead collected specimen; o.d.—
original designation; s.d.—subsequent designation.
Remarks
The subgenera Laeviscala and Graciliscala were introduced by de Boury (1909) without a formal discussion.
Both are characterised by a cancellate microsculpture
of the interstices; it is likely that the original distinction
between the two subgenera was based on the different
morphology of the ribs of the two type species. These
are close to the suture in Scalaria subauriculata and coronated on the shoulder in Scalaria gracilis (Kilburn 1985).
This latter morphological feature is shared within many
other lineages of epitoniids and in proposing Laeviscala
to be a senior synonym of Graciliscala, Iredale (1936)
probably did not consider this feature as diagnostic,
while considering the common cancellate microsculpture of the interstices as the truly diagnostic feature of
the taxon. From this point of view, this subgenus is
one of the most morphologically characteristic subgenera of the genus Epitonium. The cancellate sculpture
of the interstices may be considered one of the few
synapomorphies in a genus ‘ … in which most lineages
have arisen through the genetic reshuffling of a limited
number of characters’ (Kilburn 1985: 241).
The subgenus Laeviscala currently includes a group
of 13 species (Weil et al. 1999; Nakayama 2003) distributed mainly in the Indo-Pacific region, from South
Africa to the Central Pacific (Hawaiian Islands), with
only one species known from elsewhere: Epitonium
(Laeviscala) denticulatum (Sowerby, 1844), from the
Etymology
The name yemenita refers to the fact that this species is
described from the Red Sea coast of Yemen. The name
is used as a noun in apposition.
Description
Shell small (up to 5.4 mm in length), acuminate (b/l
0.43–0.44) (Figure 1A, C). Protoconch polygyrate,
conical, about 41/2 slightly convex whorls with fine,
incised axial striae (Figure 1G–H); basal diameter
0.36 mm; separation from teleoconch abrupt.
Teleoconch of about 5 convex whorls, increasing
regularly in size, separated by a deeply fenestrate
suture, sculptured by evenly spaced, prosocline, lamellate axial ribs, running whorl to whorl, strongly reflexed
on shoulder where they bear an evident coronation.
Penultimate and last whorl with 10 axial ribs (Figure
1B, D). Intervals with distinct spiral threads, not regularly placed, more widely spaced in the middle of the
whorl, crossed by thinner, regularly spaced, axial
striae, forming a cancellate microsculpture, not granulose at the intersection (Figure 1E–F). Aperture ovate,
peristome thick, base slightly auriculate (Figure 1A–C),
umbilicus narrowly fenestrate (Figure 1B). White in
colour. Operculum and soft parts unknown. Dimensions: holotype 4.92 × 2.1 mm; largest paratype from
MOLLUSCAN RESEARCH
121
Figure 1. A–H, Epitonium (Laeviscala) yemenita n. sp. A–B, Holotype (MZB50401), Red Sea, offshore Yemen (14°46.72′ N, 42°
32.82′ E), 76 m depth, on muddy sand. A, Ventral view, scale bar = 1 mm; B, anterior view, scale bar = 500 μm. C–H, Paratype
(MZB50403), Red Sea, Egypt, Wadi Gimal, 20 m depth. C, Ventral view, scale bar = 500 μm; D, penultimate whorl, scale bar =
100 μm; E, details of the whorl, scale bar = 100 μm; F, microsculpture of the interstices, scale bar = 50 μm; G–H, protoconch,
scale bar = 100 μm. I–J, Scalaria fucata Pease, 1861, paralectotype (NHMUK1961169), ‘Sandwich Islands’ (Hawaii). I, Details of
the penultimate whorl, scale bar = 500 μm; J, details of the microsculpture, scale bar = 100 μm. K–L, Scalaria gracilis Sowerby,
1844, syntype (NHMUK198143), Negros Island, Philippines. K, Details of the penultimate whorl, scale bar = 500 μm; L, details of
the microsculpture, scale bar = 100 μm. M–N, Graciliscala rostrata Jousseaume, 1912, holotype (MNHN-IM-2000–4392), Djibouti.
M, Details of the penultimate whorl, scale bar = 100 μm; N, details of the microsculpture, scale bar = 50 μm.
type locality 5 mm; largest paratype from Wadi Gimal
5.3 mm; largest specimen from Aqaba 5.4 mm.
Distribution
Red Sea.
Remarks
Epitonium (Laeviscala) yemenita n. sp. is morphologically
similar to E. (L.) fucatum and E. (L.) gracile, both recorded
from the Red Sea; other comparable species from the
Red Sea are also E. (L.) rostratum and E. (L.) histricosum.
122
A. BONFITTO
The new species clearly differs from E. (L.) fucatum
with its spiral threads thicker than the axial threads
(Figure 1E–F), while E. (L.) fucatum has spiral and axial
threads of similar thickness (thicker threads may
appear occasionally) (Figures 1I–J, 5M). Furthermore,
in the new species the spiral threads do not overlap
completely on the axial striae and do not form granules
at the point of intersection (Figure 1F). In contrast,
spiral and axial striae of E. (L.) fucatum produce a chessboard microsculpture with obvious granulations at the
intersections (Figures 1J, 5M). The two species further
differ in the profile of the axial ribs that in E. (L.)
fucatum are thinner, erect and slightly reflected along
the edge before the shoulder coronations.
Epitonium (Laeviscala) yemenita has more axial ribs
on the penultimate whorl than E. (Laeviscala) gracile
(10 instead of six); the ribs are lamellate, reflexed and
clearly coronated on the whorl shoulder, while in E.
(L.) gracile they are thinner, erect, reflexed near the
suture and slightly coronated on the shoulder. In
addition the two species clearly differ in the sculpture
of the interstices: in E. (L.) yemenita n. sp. the spiral
threads are more widely spaced than the axial
threads; their intersection produces rectangular
meshes without granulation at the intersection (Figure
1E–F), while E. (L.) gracile has closer and denser spiral
threads that are spaced similarly to the axial threads,
producing more squared meshes with a microscopic
granulation at the intersection (Figures 1K–L, 5C).
Epitonium (Laeviscala) rostratum was described
based on a single juvenile from the Gulf of Aden; it
has been considered by Kilburn (1985) as a synonym
of E. (L.) gracile (see additional notes). In respect to
the new species it has fewer axial ribs on the penultimate whorl (six instead of 10), lower coronation on
the shoulder and interstices more densely reticulated
with closer axial threads (Figures 1M–N, 5A–B).
Epitonium (Laeviscala) histricosum, from the Red Sea,
a species whose attribution to Laeviscala was questioned by Kilburn (1985), differs from the new species
by its weakly reticulated interstices, with feeble spiral
threads and faint axial fillets (Figure 5D–I) and fewer
axial ribs (7–8 instead 10).
The new species can be easily distinguished from E.
(Laeviscala) subauriculata (Souverbie, 1866) (type
species of subgenus), E. (Laeviscala) sandwichense, E.
(Laeviscala) luceo (Du Shane, 1988), E. (Laeviscala)
tacitum and E. (Laeviscala) morassii n. sp. in having
coronated axial ribs (Figure 1A, C, D), while all the previous species have axial ribs regularly rounded toward
the suture and not coronated on the shoulder (e.g.
Figure 2A, C, I).
Epitonium (Laeviscala) morassii n. sp.
Figure 2A–I
Holotype. Red Sea, Zabargad Island, 23°37.20′ N, 36°
11.30′ E, 25 m depth, in coral sand (MZB50404, coated).
Paratype. Red Sea, Egypt, Sinai, 27°52.44′ N, 34°20.51′ E,
20–25 m depth (MZB50405, coated).
Material examined
Type material. See above.
Etymology
Named after Dr Mauro Morassi from Brescia, Italy in recognition of his contribution to the field of malacology,
in particular to the turriform gastropods.
Description
Shell small (up to 7.1 mm in length), slender conical (b/l
0.4) (Figure 2A, E). Protoconch polygyrate, broadly
conical, of 4.5 slightly convex, glossy whorls with fine,
incised axial striae and very faint spiral striae, particularly evident on the last whorl (Figure 2H); separation
from teleoconch abrupt; basal diameter 0.3 mm. Teleoconch of about 8 convex whorls (about 6 in the paratype), increasing regularly in size, separated by a very
deep suture (Figure 2A–B, E–F). Axial ribs evenly
spaced, prosocline, moderately thick, lamellate, rather
low, running whorl to whorl, very strongly reflexed
over their entire length, with involute crests, not coronate, 8–9 on penultimate whorl (Figure 2A–B, D–F).
Interstices with distinct cancellate microsculpture,
with spiral striae thicker than the axial striae (Figure
2C, G). Spiral threads closer towards the periphery of
the whorl and more widely spaced in the middle,
where they can be interspersed with occasional secondary fillets (Figure 2G). Axial threads cross and
overlap spiral threads forming meshes which appear
squared at the periphery of the whorl, more rectangular in the middle (Figure 2C, G). Reticulate microsculpture absent on the costae, which appear axially
lamellate. Aperture subcircular, slightly shifted backward, with a broad callus at its columellar side. Umbilicus narrow and crossed by the extremities of the axial
costae (Figure 2A, E). White in colour. Operculum and
soft parts unknown.
Dimensions. Holotype 7.08 × 2.83 mm; paratype
4.42 × 1.75 mm.
Distribution
Northern Red Sea.
Remarks
Epitonium (Laeviscala) morassii n. sp. is morphologically very similar in shape, number and profile of
axial ribs to E. (L.) tacitum from Australia (Figure 2J–
K). Both species have axial ribs very strongly reflexed
MOLLUSCAN RESEARCH
123
Figure 2. A–G, Epitonium (Laeviscala) morassii n. sp. A–C, Holotype (MZB50404), Red Sea, Egypt, Zabargad Island, 25 m depth. A,
Ventral view, scale bar = 1 mm; B, penultimate whorl, scale bar =100 μm; C, microsculpture of the interstices, scale bar = 100 μm.
D–I, Paratype (MZB50405), Red Sea, Egypt, Sinai, 20–25 m depth. D, Posterior view, scale bar = 500 μm; E, ventral view, scale bar =
1 mm; F, penultimate whorl, scale bar = 100 μm; G, microsculpture of the interstices, scale bar = 100 μm; H–I, protoconch, scale bar
= 100 μm. J–M, Epitonium (Laeviscala) tacitum (Iredale, 1936). J–K, Holotype of Laeviscala tacita Iredale, 1936, Sydney Harbour,
NSW (Australian Museum, C.345617) (microphotographs by Des Beechey). J, Ventral view, scale bar =10 mm; K, details of the microsculpture of the interstices, scale bar = 2 mm. L–M, Specimen from Cairns, Green Island, Queensland, Australia, 2 m depth, in coral
sand (MZB50410). L, Details of the penultimate whorl, scale bar = 500 μm; M, microsculpture of the interstices, scale bar = 100 μm.
and with similar approximately tubular shape (Figure
2A–B, D–F, G–H, I–J). However, E. (L.) morassii n. sp. is
much smaller than E. (L.) tacitum and has a different
sculpture of the interstices. In the new species the
spiral threads are thicker than the axial ones and irregularly distributed; they are more spaced to the
centre of the whorls and closer to the periphery
(Figure 2B–C, F–G). In E. (L.) tacitum, the
124
A. BONFITTO
Table 1. Dimensions of the lectotype and the paratypes of
Graciliscala histricosa Jousseaume, 1912.
Lectotype (Figure 5D)
Paralectotype (Figure 5F)
Paralectotype (Figure 5G)
Paralectotype (Figure 5H)
Paralectotype (Figure 5I)
l (mm)
b (mm)
10.83
12.33
11
10.33
8.66
4.33
4.5
4.83
4.5
3.83
microsculpture clearly differs in having axial and spiral
threads similar in thickness and uniformly placed
between the centre and the periphery of the teleoconch whorls, forming a denser reticulated sculpture
than the new species (Figure 2K–M). There are no
other comparable species.
Subgenus Labeoscala de Boury in Jousseaume,
1912: 214
Type species (by virtual tautonomy) Labeoscala labeo
Jousseaume, 1912
Diagnosis
Shell small, pyramidal to ovate-elongate, suture simple,
axial ribs not coronate, intervals with spiral threads,
umbilicus barely fenestrate or rimate, peristome
greatly thickened.
Remarks
The subgenus Labeoscala appears morphologically
less distinctive than the subgenus Laeviscala; no
single character separates this taxon from the
several subgenera of Epitonium. In the aggregate,
however, the combination of several morphological
features (greatly thickened peristome, costae not
coronated, spiral sculpture of the interstices, umbilicus narrowly rimate or barely fenestrate) makes diagnosis relatively easy. In addition to the two new
species here described the taxon currently includes
eight species (Kilburn 1985; Weil et al. 1999), two of
which, E. (Labeoscala) labeo and E. (Labeoscala) perimense, have been recorded in the Red Sea (Dekker
and Orlin 2000).
Epitonium (Labeoscala) zabargadense n. sp.
Figure 3A–H
Holotype. Red Sea, Egypt, Zabargad Island, 23°37.20′ N,
36°11.30′ E, 27 m depth, in coral sand (MZB50406,
coated; Figure 3A–H).
Paratype. Red Sea, offshore Yemen, 14°46.72′ N, 42°
32.82′ E, 76 m depth, on muddy sand (MZB50407,
coated).
Material examined
Type material. See above.
Etymology
The name zabargadense refers to the fact that this
species is described from Zabargad Island.
Description
Shell solid, small (up to 2.6 mm), relatively slender,
ovate-elongate profile (b/l 0.47) almost rissoiniform,
with the last whorl representing more than 60% of
the total shell length (Figure 3A–B). Protoconch
conical, globose, of about 3.5 whorls, basal diameter
0.39 mm, white (Figure 3G–H). Teleoconch of about
3.5 inflated, regularly convex whorls, separated by a
moderately deep suture. The axial sculpture consists
of strongly reflected ribs, almost tubular, slightly prosocline, narrower than the interstices, not coronated,
occasionally varix-like or bisected, not continuous
from whorl to whorl; 22 on penultimate whorl. Intervals
with 12–13 raised spiral threads, with occasional faint
secondary axial striae (Figure 3E–F). Aperture oval.
Outer lip thickened, columella expanded at the base.
Umbilicus rimate and concealed by the partially
reflexed columellar lip (Figure 3D). White in colour.
Operculum and soft parts unknown. Dimensions. Holotype 2.1 × 1.1 mm; paratype 2.5 × 1.3 mm.
Remarks
Epitonium (Labeoscala) zabargadense n. sp. is very
similar to E. (Labeoscala) rissoinaeforme (Melvill &
Standen, 1903) in many aspects such as general shell
morphology, oval aperture, convexity of the teleoconch whorls and sculpture of the interstices. The
new species differs in having a smaller shell (up to
2.6 mm) and about 22 axial ribs and 12 to 13 spiral
threads on the penultimate whorl. In contrast, E. (L.) rissoinaeforme is larger (up to 4.2 mm) and has 25 to 28
axial ribs and 22–25 spiral threads on the penultimate
whorl. Furthermore, the protoconchs of the two
species are different in shape, size and ornamentation.
In the new species it is more globose and consists of 3.5
whorls only axially striate (Figure 3G–H); the protoconch of E. (L.) rissoinaeforme is dome shaped, consists
of 4 whorls that are ornamented by axial striae and a
subsutural spiral fillet particularly evident on the last
whorl (Figure 3K–L).
The remarks presented herein on the shell morphology of E. (L.) rissoinaeforme are based on the
direct examination of the syntypes NHMUK
1903.12.15.17 (Figure 3I–L) and NHMUK1981209
(Figure 3M–R).
Epitonium (Labeoscala) aranea n. sp.
Figure 4A–K
Holotype. Red Sea, off Yemen, 14°46.72′ N, 42°32.82′ E,
76 m depth, on muddy sand (MZB50408, coated).
MOLLUSCAN RESEARCH
125
Figure 3. A–H, Epitonium (Labeoscala) zabargadense n. sp., holotype (MZB50406), Red Sea, Egypt, Zabargad Island, 27 m depth. A–
B, Ventral and lateral view, scale bar = 500 μm; C, anterior view, scale bar = 500 μm; D, ultimate whorl, scale bar = 500 μm; E,
penultimate whorl, scale bar = 100 μm; F, microsculpture of the interstices, scale bar =100 μm; G–H, protoconch, scale bar =
100 μm. I–R, Epitonium (Labeoscala) rissoinaeforme Melvill & Standen, 1903, syntypes, Gulf of Oman (24°58.00′ N, 26°54.00′ E),
F.W. Townsend collection (microphotographs by Harry Taylor, NHMUK Photographic Unit). I–L, Syntype (NHMUK 1903.12.15.17).
I, Ventral view, scale bar = 1 mm; J, details of the whorl, scale bar = 100 μm; K–L, protoconch, scale bar = 100 μm. M–R,
Ventral, posterior and lateral view of two syntypes (NHMUK1981209), scale bar = 1 mm.
Paratypes. Red Sea, off Yemen, 14°46.72′ N, 42°32.82′ E,
76 m depth (MZB50409, 2 spm; MNHN-IM-2014-6668,
1 spm; NHMUK, 1 spm. All coated).
Material examined
Type material. See above.
126
A. BONFITTO
Figure 4. A–K, Epitonium (Labeoscala) aranea n. sp. A–I, Holotype (MZB50408), Red Sea, offshore Yemen (14°46.72′ N, 42°32.82′ E),
76 m depth. A–C, Ventral, lateral and posterior view, scale bar = 500 μm; D, penultimate whorl, scale bar = 100 μm; E, microsculpture of the teleoconch, scale bar = 50 μm; F, last whorl, scale bar = 500 μm; G–H, protoconch, scale bar = 100 μm; I, details of the
protoconch, scale bar = 10 μm. J–K, Paratype 1 (MZB50409). J, Ventral view, scale bar = 1 mm; K, outer lip, scale bar = 500 μm. L–O,
Ventral, posterior, lateral and dorsal view of Scala thelcteria Melvill & Standen, 1903, syntype (NHMUK 1903.12.15.17), Mussandam,
Persian Gulf, F.W. Townsend collection, scale bar =1 mm (microphotographs by Harry Taylor, NHMUK Photographic Unit).
Etymology
From the Latin aranea, meaning ‘spiderweb’, alluding
to the geometry of the ornamentation of the shell of
the new species. The name is used as a noun in
apposition.
Description
Shell small (up to 4.42 mm), pyramidal (b/l 0.49–0.50).
Protoconch conical, glossy, of about 3.5 whorls, axially
striate; basal diameter of 0.35 mm (Figure 4G–I). Teleoconch of about 6 convex whorls, relatively globose, separated by a deep suture, not fenestrate, sculptured by
erect, slightly frilly axial ribs, regularly placed, prosocline,
not continuous, about 29 on penultimate whorl (Figure
4A–D), interspaces with erect spiral threads, about 11 on
penultimate whorl. The crossing between axial ribs and
spiral threads creates a characteristic reticulated sculpture of regular meshes. Surface among sculptural
elements smooth (Figure 4E). Aperture oval, columella
auriculate, outer lip very thick, varicoid, lamellate
(Figure 4K). Umbilicus narrowly rimate (Figure 4F). Operculum and soft parts unknown.
Dimensions. Holotype 4.42 mm × 2.17 mm; largest
paratype 3.5 mm × 1.75 mm (MZB50409).
Distribution
Known only from type locality.
MOLLUSCAN RESEARCH
127
Figure 5. A–B, Graciliscala rostrata Jousseaume, 1912, holotype (MNHN-IM-2000-4392), Djibouti. A, Ventral view, scale bar =
500 μm; B, details of the microsculpture, scale bar = 50 μm. C, Scalaria gracilis Sowerby, 1844, syntype (NHMUK198143), details
of the microsculpture, scale bar = 500 μm. D–I, Graciliscala histricosa Jousseaume, 1912 (MNHN 4258), Red Sea. D–E, Lectotype.
D, Ventral view, 10.83 × 4.3 mm; E, details of the microsculpture, scale bar = 100 μm. F–I, Paralectotypes (see Table 1 for dimensions). J–M, Epitonium (Laeviscala) fucatum (Pease, 1861). J–K, Specimen from lot MNHN4258. J, Ventral view, 11.1 mm × 4.8 mm;
K, details of the microsculpture, scale bar = 100 μm. L–M, Scalaria fucata Pease, 1861, paralectotype (NHMUK1961169), Sandwich
Islands (Hawaii Islands). L, Ventral view, scale bar = 1 mm; M, details of the microsculpture, scale bar = 500 μm. N–P, Epitonium
(Laeviscala) gracile (Sowerby, 1844) from lot MNHN4258 with dimensions, respectively, of 9.67 mm × 4.33 mm (N) and 8.67 mm ×
3.83 mm (O). P, Details of the microsculpture of the specimen N, scale bar = 100 μm.
128
A. BONFITTO
Remarks
The new species somewhat resembles Epitonium (Sodaliscala) avalites (Jousseaume, 1912) from the Red Sea
and Epitonium (Labeoscala) thelcterium (Melvill &
Standen, 1903) from the Persian Gulf and the Maldives.
It can be distinguished from E. (S.) avalites (type specimen available at MNHN 2017a) by its wider shape (b/l
0.50 instead of 0.45), a different number of axial ribs
(29 instead 17) and spiral threads (11 instead 12–13 on
the penultimate whorl); furthermore, in E. (S.) avalites
the axial and spiral threads form a reticulate sculpture
in which the rectangular meshes are more elongated
and flattened than in E. (L.) aranea n. sp.
The new species is wider than E. (L.) thelcterium
(Figure 4L–O) (b/l 0.45 instead of 0.50) and it has
more axial ribs (29 instead of 15) and spiral threads
(11 instead of 8) on the penultimate whorl (Figure 4L,
N–O). Moreover, in the new species the spiral and
axial threads have about the same thickness while in
E. (L.) thelcterium the spiral sculpture prevails over the
axial sculpture.
The remarks presented herein on the shell morphology of E. (L.) thelcterium are based on the direct
examination of syntypes (NHMUK1903.12.15.17).
Additional notes
Graciliscala rostrata Jousseaume, 1912 was considered
by Kilburn (1985) as a probable synonym of Scalaria
gracilis Sowerby, 1844. Although accepted by Weil
et al. (1999), this supposed synonymy does not seem
to be justified by the comparison of type specimens.
In contrast to the syntype of S. gracilis (Figures 1K–L,
5C), the holotype of Graciliscala rostrata (Figures 1M–
N, 5A–B) has fewer axial ribs (six instead of 7–8),
lower shoulder coronation and different reticulate
microsculpture. In G. rostrata the spiral threads are
more spaced than the axial threads (Figure 5B) and
form a reticulate sculpture with rectangular and vertically elongate meshes in contrast with the squared
meshes that characterise the reticulate sculpture of
S. gracilis (Figure 5C).
In WoRMS (2017) Graciliscala rostrata is currently
considered a synonym of Avatiliscala gradilis Jousseaume, 1912 from the Red Sea (type specimen available at MNHN 2017b). Based on my personal
observations of the type specimens of both species
carried out at the MNHN in Paris, I do not agree with
this synonymy: A. gradilis has 10 axial ribs and interstices not reticulated while G. rostrata has six axial
ribs and the interspaces are clearly reticulated. In my
opinion these macroscopic differences suggest that
they are two different taxa.
The syntype series of Graciliscala histricosa Jousseaume, 1912, from the Red Sea (MNHN 4258), contains
eight specimens from various localities (Suez, Aden,
Djibouti and Périm), all figured in Jousseaume (1912).
Examination of morphology reveals that the lot contains
specimens belonging to different taxa. Five specimens
(Figure 5D, F–I) have seven axial ribs on the last whorl
with the interstices sculptured by clear spiral striae
and very faint axial scratches; consequently, the reticulated sculpture is very little engraved and mainly
restricted to the periphery of the whorl (Figure 5E).
The weakly reticulated sculpture led Kilburn (1985) to
state that this species would have a more appropriate
placement in Parviscala de Boury, 1887; in my opinion
this character is manifested sufficiently to continue to
consider this species as Laeviscala. These five specimens
can be assigned to Graciliscala histricosa. In order to
stabilise the name, the specimen marked with a red
spot that most closely matches measurements given
in the original description is here designated as the lectotype (dimension 10.83 mm × 4.3 mm; dimension
given in original description: 11 mm × 4 mm); the four
other shells are paralectotypes (Art. 74, ICZN 1999)
(Figure 5F–I) (see Table 1 for dimensions).
Among the others, the specimen labelled J in Figure
5 (dimension 11.08 × 4.83 mm) has nine axial ribs on
the last whorl; the ribs are continuous, erect, clearly
coronated on the shoulder and strongly reflexed near
the suture. The interstices are visibly reticulated. The
axial and spiral threads are slightly different in thickness and more or less regularly spaced; their intersection has raised squared meshes with a microscopic
granulation at the points of junction (Figure 5K). This
specimen matches the paralectotype of E. (Laeviscala)
fucatum (NHMUK1961169) (Figure 5L–M) to which
species it may be assigned.
The last two specimens (Figure 5N–O) have, respectively, eight and seven axial ribs on the last whorl
(dimensions: 9.67 × 4.33 mm and 8.67 × 3.83 mm); the
ribs are continuous, reflexed along the edges, particularly near the suture, with a blunt coronation on the
shoulder. The interstices are clearly reticulated. The
spiral and axial threads have slightly different thicknesses; both are more or less evenly spaced and their
intersection produces squared meshes with a microscopic granulation at the points of junction (Figure
5P). All these features are shared with the syntype of
Scalaria gracilis (NHMUK198143) (Figure 5C) to which
species they may be assigned.
Conclusion
Modern malacological literature indicates that approximately 1800 species of molluscs are listed as present in
the Red Sea, about 300 of which have been recorded
from over 400 m deep (Mastaller 1987; Dekker and
Orlin 2000; Janssen and Taviani 2015). However, considering the environmental complexity of this basin, it
is probable that the actual biodiversity of the phylum
is underestimated and that the species richness could
MOLLUSCAN RESEARCH
be increased by working on samples from poorly
studied areas, such as deep waters, and on the micromolluscs. This will increase not only the knowledge of
the malacofauna of the Red Sea, but also provide a
better understanding of its relations with the malacofauna of the Indian Ocean.
Acknowledgements
I am grateful to Andreia Salvador and Harry Taylor (NHMUK,
London) for the loan of type specimens and for the photographs of the syntype of Scala rissoinaeformis and Scala thelcteria; Des Beechey (Australian Museum, Sydney), who has
kindly provided photographs of the holotype of Laeviscala
tacita; Virginie Héros (MHNH, Paris) for the loan of the Jousseaume’s type specimens and for her usual courtesy and
helpfulness; Dr Mauro Morassi (Brescia, Italy); Professor
Bruno Sabelli (University of Bologna, Italy); Dr Paolo Albano
(University of Vienna, Austria) and two anonymous reviewers
for their useful comments and constructive criticism on an
early draft of the manuscript; Dr Marco Taviani (Italian
National Research Council), Italian partner of European Community project RED SED (The Red Sea and Gulf of Aden Sedimentological Project, 1991–93) who within this project has
made possible my participation to two scientific missions in
the Red Sea, during which some of the specimens discussed
here were collected, and also for his contribution to the
increase of the malacological collection of the Zoological
Museum of the University of Bologna.
Disclosure statement
No potential conflict of interest was reported by the author.
Funding
This work was supported by the “Canziani Bequest” fund, University of Bologna, [grant number A.31.CANZELSEW],
Bologna, Italy.
ORCID
Antonio Bonfitto
http://orcid.org/0000-0001-9399-4208
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