Zootaxa 3925 (3): 445–449
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ZOOTAXA
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http://dx.doi.org/10.11646/zootaxa.3925.3.9
http://zoobank.org/urn:lsid:zoobank.org:pub:09962D19-6BDF-4E06-B9B1-2760DDD3236E
A new freshwater snail (Caenogastropoda: Cochliopidae)
from the Atacama Desert, northern Chile
GONZALO A. COLLADO
Departamento de Ciencias Básicas, Facultad de Ciencias, Universidad del Bío-Bío, Avenida Andrés Bello s/n, Casilla 447, Chillán,
Chile. Fundación Chile Natura. E-mail: [email protected]
In the family Cochliopidae, Heleobia Stimpson, 1865 is the most speciose genus in South America, with about 90
species (Hershler & Thompson 1992; Cazzaniga 2011). A recent molecular and morphological analysis performed in
northern Chile (Atacama Desert) showed that the previously undescribed springsnails from Aguada de Chorrillos belong
to Heleobia (Collado et al. 2013). In this study I formally describe this new species. Although this paper does not treat
morphology in detail, the anatomical characters, in combination with the previously published molecular data provides a
strong basis for recognizing this population as a distinct species.
Material and methods
The snails were collected alive from Aguada de Chorrillos (27°12′32.40″ S; 70°57′03.30″ W), Atacama Desert, northern
Chile using a sieve of 0.5 mm mesh width and stored in absolute ethanol. The shells, opercula and penes were
photographed and measured using a Motic SMZ–168 Stereo Microscope with a Moticam 2000 integrated digital camera.
Type specimens were deposited in the Museo de Zoología de la Universidad de Concepción (MZUC), Concepción,
Chile. Measurements in mm are presented as: mean ± standard deviation (minimum–maximum). Abbreviations: SL,
shell length; SW, shell width; AL, aperture length; AW, aperture width.
Systematics
Class Gastropoda Cuvier, 1795
Order Littorinimorpha Golikov & Starobogatov, 1975
Family Cochliopidae Tryon, 1866
Subfamily Semisalsinae Giusti & Pezzoli, 1980
Genus Heleobia Stimpson, 1865
Species Heleobia deserticola sp. nov.
Holotype. (MZUC 43067, Fig. 1A). Collected by G.A. Collado from Aguada de Chorrillos, Chile (28 November 2011).
Holotype measurements: SL 4.41 mm, SW 2.10 mm, AL 2.00 mm, AW 1.21 mm.
Paratypes. (MZUC 43068–43077, Fig. 1B–K). Snails from Aguada de Chorrillos, Chile, collected with the
holotype by G.A. Collado. Morphometric data of the paratypes (n = 10): SL: 4.01 ± 0.31 (3.40–4.40); SW: 1.99 ± 0.13
(1.80–2.20); AL: 1.76 ± 0.19 (1.40–2.00); AW: 1.22 ± 0.15 (1.00–1.40); SW/SL: 0.50 ± 0.02 (0.46–0.53); AL/SL: 0.44 ±
0.04 (0.35–0.47); AW/AL: 0.07 ± 0.08 (0.61–0.86).
Description. Shell small, elongate–conic, thin, transparent, smooth, suture depth, closed umbilicus (imperforate).
Adults with 6 to 7 convex whorls. Aperture ovate, outer lip thin. Operculum corneous, ovate, flat, thin, light brown,
Accepted by M. deMaintenon: 22 Jan. 2015; published: 2 Mar. 2015
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paucispiral (Fig. 1L). Foot, mantle and tentacles gray, head black, snout white, visceral sac yellow to light brown. Penis
elongated, white–grayish; proximal portion with a wide base, with 5–6 cup–shaped apocrine glands on the border (Fig.
1M–O); distal portion tapers to an elongated conical tip. One or two additional aprocrine glands are located in the convex
side of the penis.
Reproductive biology. This species is gonochoric, with direct development. Several individuals sampled in Aguada
de Chorrillos bore single egg capsules attached to the shells with an embryo or a juvenile snail inside, depending on the
stage of development (Fig. 1P, Q).
Type locality. Aguada de Chorrillos, a small spring located at the Pacific coast in the Atacama Desert, northern
Chile (Fig. 2A, B), 5 m above sea level. The site is located several kilometers north of the mouth of the Copiapó River,
which is separated from it by an arid desert. The water of the spring arises from the walls of a canyon about 10 m high
that form pools (Fig. 2B) at the bottom of the ravine which eventually drains to the sea.
Distribution and habitat. The snails were collected from the small puddles of water (c. 10 cm depth) on soft
substrate in the spring Aguada de Chorrillos. In November 2011 individuals of all size ranges from this locality were
sampled.
Etymology. The name is a compound noun meaning desert dweller; it is derived from the area of origin of the new
species.
Remarks. Heleobia deserticola sp. nov. can be distinguished from the other species of the genus by its particular
penis morphology (Fig. 1M–O), including the wide portion of the base of the organ, several apocrine glands located
around of the complete margin of the base and the additional aprocrine glands located in the convex side of the central
portion of the organ. All these characters as a whole differentiate this species from other species of the group whose penis
morphology is known (e.g. Hubendick 1955; Gaillard & de Castellanos 1976; Hershler & Thompson 1992; Collado et al.
2011; Ovando & De Francesco 2011; Collado 2012; Collado et al. 2013). The sister group of this species is an
undescribed population from Carrera Pinto, northern Chile (Collado et al. 2013), a spring separated from Aguada de
Chorrillos by over 100 km of arid desert. I did not treat these populations as conspecific because of differences in shell
and penis morphology (Fig. 1R, S). The shell of the snails from Carrera Pinto has a band in the growing whorls not
present in Heleobia deserticola sp. nov. while the penis has aprocrine glands only on the convex side of the base. The
snails from Aguada de Chorrillos and Carrera Pinto belong to the clade including Heleobia transitoria (Biese, 1947), and
a population from Quebrada El León in the Atacama Desert. These snails are not very close to Heleobia opachensis
(Biese, 1947), Heleobia loaensis (Biese, 1947), Heleobia chimbaensis (Biese, 1944), Heleobia ascotanensis (Courty,
1907) and Heleobia atacamensis (Philippi, 1860) (Collado et al. 2013) described from northern Chile.
Comparison with the other Heleobia species. Heleobia deserticola sp. nov. fits well the morphological
characteristics of the shell and penis of the genus as defined by Hershler & Thompson (1992), with the male copulatory
organ possessing aprocrine glands. Additionally, the new species was also placed in the genus Heleobia based on a
molecular phylogenetic analysis (Collado et al. 2013). Of the nominal species of Heleobia from northern Chile, Heleobia
deserticola sp. nov. is the third representative described from the coast of the Atacama Desert after H. chimbaensis and
H. transitoria. The shell of the new species is little differentiated morphologically from other regional congeners [see
Collado et al. (2011), Collado (2012), Collado et al. (2013) for comparative purposes]. The closed umbilicus of the new
species resembles that of H. atacamensis, H. loaensis, H. opachensis and H. transitoria. Heleobia deserticola sp. nov.
has direct development, similar to the reproductive strategy employed by H. chimbaensis, Heleobia parchappii
(d’Orbigny, 1835), Heleobia miaulis (Marcus & Marcus, 1965) and Heleobia guaranitica (Doering, 1885) (Marcus &
Marcus 1965; Gaillard 1973; Cazzaniga 1982; Collado & Méndez 2011); other species of Heleobia have indirect
development (see Collado & Méndez 2011). The black pigmentation of the head of H. deserticola sp. nov. differs from
that of Heleobia neveui (Bavay, 1904) because the latter species in general is less pigmented (Hubendick 1955). The gray
pigmentation of the tentacles of H. deserticola sp. nov. differs from that of Heleobia compacta (Haas, 1955), Heleobia
cumingii (d’Orbigny, 1835) and Heleobia aperta (Haas, 1955) from Lake Titicaca, which are almost black over all these
structures (Hubendick 1955). Heleobia is divided into two groups on the basis of the size (Biese 1944, 1947). The group
of Heleobia hatcheri (Pilsbry, 1911), which contains small species, with 4–5 shell whorls, and the group of H.
parchappii, which contains larger forms, with 5–8 whorls. The new species belongs to the second group; adult
individuals can reach up to seven whorls.
Heleobia deserticola sp. nov. is only known from the spring of Aguada de Chorrillos (Collado et al. 2013; present
study). This oasis is an extremely small restricted habitat, surrounded by an arid desert and facing the sea. In northern
Chile, several localities with populations of Heleobia are subjected to anthropogenic pressures, pollution or water
scarcity (Collado 2012). Recently, two species of Heleobia in the Atacama Desert, H. atacamensis and H. chimbaensis
were declared Critically Endangered and Vulnerable, respectively (Collado 2013a,b), according to the list of the
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COLLADO
threatened species of the Ministerio del Medio Ambiente, República de Chile. It is clear that some biological and
population parameters need to be estimated by monitoring Heleobia deserticola sp. nov. because any alteration to the
biotope could affect the population of these snails in Aguada de Chorrillos. There are currently no conservation measures
for this particular place.
FIGURE 1. A–Q. Heleobia deserticola sp. nov. A. Shell of the holotype (MZUC 43067). B–K. Shells of the paratypes
(MZUC 43068–43077). L. Operculum (1.70 mm total length). M–O. Penes of three individuals (0.64, 0.70 and 0.90 mm
total length, respectively). Operculum and penes were photographed from both sides. P, Q. Egg capsules of the new
species. P. Egg capsules attached to the adult shells. Q. Pre–hatching capsule isolated with a shelled juvenile inside. R.
Shell of an adult snail from Carrera Pinto (SL 3.51 mm, SW 1.55 mm, AL 1.35 mm, AW 0.97 mm. S. Penis of this
individual (0.75 mm total length).
NEW SPECIES OF HELEOBIA FROM THE ATACAMA DESERT
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FIGURE 2. Aguada de Chorrillos, Atacama Desert, northern Chile, the type locality of Heleobia deserticola sp. nov. A.
Panoramic view of the system, desert, beach and Pacific Ocean. B. Spring where the snails live.
Acknowledgments
I am grateful to Dr. Jorge Artigas, curator of the Museo Nacional de Historia Natural de Concepción, Chile. I also thank
Sergio Araya for taking the photographs from the type locality and the anonymous reviewers who improved the original
manuscript. This paper was supported by FONDECYT, grant number 11130697.
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