Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 March 2021 | 13(3): 17999–18003
ISSN 0974-7907 (Online) | ISSN 0974-7893
(Print)
https://doi.org/10.11609/jott.6193.13.3.17999-18003
#6193 | Received 20 May 2020 | Final received
19 January 2021 | Finally accepted 07 March 2021
Sandracottus vijayakumari (Coleoptera:
Dytiscidae), a new aquatic beetle species from
landslide hit area of Nelliyampathy Forest Range, Western
Ghats, Kerala, India
P.P. Anand 1, P.P.
Ashiq 2, M. Smitha 3, M. Adhithya
4, T. Tibin 5 & V. Suresh 6
1–6 Department of Botany, Government
Victoria College, Palakkad, Kerala 678001, India.
1 Department of Zoology, University
of Calicut, Tirur-Kozhikode Road, Thenhipalam,
Kerala 673635, India.
2 Salim Ali Centre for Ornithology
and Natural History (SACON), Anaikatty, Coimbatore,
Tamil Nadu 641108, India
1 anandpp633@gmail.com
(corresponding author), 2 ashiqleo7@gmail.com, 3 smithathottingal@gmail.com,
4 adhithyamohan@gmail.com,
5 tibinthomas312@gmail.com, 6 sureshmagnolia@gmail.com
(corresponding author)
ZooBank: urn:lsid:zoobank.org:pub:A04B95E7-E565-413D-B6AD-32A0DA508D9E
Editor: Asheesh Shivam
Mishra, Nehru Gram Bharati, Prayagraj, India. Date
of publication: 26 March 2021 (online & print)
Citation: Anand, P.P., P.P. Ashiq, M.
Smitha, M. Adhithya, T. Tibin
& V. Suresh (2021). Sandracottus vijayakumari
(Coleoptera: Dytiscidae), a new
aquatic beetle species from landslide hit area of Nelliyampathy
Forest Range, Western Ghats, Kerala, India. Journal of Threatened Taxa 13(3): 17999–18003. https://doi.org/10.11609/jott.6193.13.3.17999-18003
Copyright: © Anand et al. 2021. Creative Commons Attribution
4.0 International License. JoTT allows unrestricted use, reproduction, and
distribution of this article in any medium by providing adequate credit to the
author(s) and the source of publication.
Funding: KERALA STATE BIODIVERSITY BOARD
order No. 48/3371/2018/KSBB dated 19.12.2018.
Competing interests: The authors
declare no competing interests.
Acknowledgements: The authors gratefully
acknowledge the financial assistance of Kerala State Biodiversity Board (KSBB),
Government of Kerala, India. The first
author is grateful to Dr. Y. Shibu Vardhanan, associate professor, Department of Zoology,
University of Calicut for providing department laboratory facilities (UGC-SAP)
and photographic documentation.
Abstract: The present study deals with
the description of a new species Sandracottus
vijayakumari from Nelliyampathy
forest range, southern Western Ghats, Kerala, India with a comparative key of
closely related species S. dejeani Aube,
1838. Only one species is known from the
genus Sandracottus Sharp, 1882, from
southern Western Ghats, Kerala. The Nelliyampathy forest areas are hilly and the altitude of
the hills range 40–1,530 m. The region
experiences several types of landslides especially during the monsoon (August
to September 2018). The new species was
discovered in one of the worst landslide hits area in Nelliyampathy
forest, Kundrachola region. The new aquatic beetle species is moderately
large in size and often very attractively marked dorsally with complex maculations.
Additionally, the new species shows a strong synapomorphy along with Eretini, Hydaticini, and Aubehydrini tribes.
Keywords: Aquatic beetle, insect, Kundrachola, monsoon, southern Western Ghats.
The adephagan beetles are one of the most successful
groups of insects, distinguished by their adaptive nature in diverse ecological
and geographical ranges. Most aquatic
beetles are considered ecological indicators and their diversity is directly
correlated with the ecosystem (Hutchison 1959; Boughey
1968; Benetti et al. 2003; Benetti & Regil-Cueto
2004). The factors like wave action,
wind velocity, and scarcity of emergent vegetation presumably discourage the
colonization of aquatic beetles. The
abundance of macrophytic vegetation provides
necessary shelter, shade, and substrate for colonization of aquatic beetles in
the rainy and post-rainy season (Fernando 1968). Seasonal variation of the insect community in
the rain pools, biotic patterns, some physical and meteorological variables
were analyzed and found that the maximum taxonomic
richness was observed at the end of summer (Fischer et al. 2000).
In India, the aquatic beetle diversity is poorly
known. Dytiscidae
is a large family of aquatic beetles, harbouring over ~300 species in India and
adjacent countries. The Indian dytiscids have been chiefly studied by Vazirani
(1968–1977) where he dealt with 233 species from India, out of which 69 species
are from southern India. Till date, the
majority of southern Indian species have been recorded from Tamil Nadu
including Nilgiri Hills (Mukherjee & Sengupta
1986). During the biodiversity
documentation of the flood and landslide hit area of Nelliyampathy,
the authors came across a new species of Sandracottus
Sharp, 1882 to science which has been described here and its comparison with
the closely related species S. dejeani
Aube, 1838 is also provided along with identification keys.
Materials and Methods
Study area
The present study was conducted at various locations
in the Nelliyampathy Hills, Western Ghats, Kerala,
India in view of the floods and landslides that occurred as a result of the
heavy downpour of August and September 2018 that resulted in heavy damage in
Kerala, India.
Specimen collection
Specimens were collected from a small rock of pool
habitat in the landslide hit area of Nelliyampathy
forest range in Kundrachola region (515m, 10030’58’’N
& 76037’51”E) of southern Western Ghats (Image 1, 2). An
aquarium hand net (Miller & Bergsten 2016) was used to collect the samples
during the cool dry season from January to March 2019; a total of seven
specimens were collected from the field and preserved in 80% ethanol prior to
mounting. The holotype and paratype is
deposited in the Department of Zoology, University of Calicut (DZUC). Specimens were imaged with a Canon EOS 5D
Mark IV camera with MP-E 65mm lens, f/2.8 1-5X.
Morphological terminology is according to Miller & Bergsten
(2016). Identification was done based on
available literature and taxonomic keys (Regimbart
1899; Mukherjee & Sengupta 1986; Nilsson 2001; Miller & Bergsten 2014;
Miller & Bergsten 2016).
Results
Systematic position
Family: Dytiscidae Leach,
1815
Subfamily: Dytiscinae Leach,
1815
Tribe: Aciliini Thomson,
1867
Genus: Sandracottus
Sharp, 1882
Sandracottus vijayakumari sp. nov.
(Image 3A–D)
urn:lsid:zoobank.org:act:5885D8BA-1045-4CEE-A42C-4D2496FCB5F9
Material examined: Holotype: DZUC/Dyt01/2020, 17.iii.2019, male, India:
Kerala, Palakkad, southern Western Ghats, Nelliyampathy
forest range- Kundrachola (10030’58’’N
& 76037’51”E), coll. P.P. Anand.
Paratype: DZUC/Dyt02/2020, 1 male with same data as
holotype.
Description: Holotype male: length= 16.0mm; width= 13.5mm. Body oval, elongated; surface shiny; latteral reddish-orange colored
line become reduced by reaching the posterior end of the pygidium; not dorso-ventrally flattened. Deep punctures on the pronotum
and elytra. Dorsal surface black with
distinct reddish-orange patches and with four dark-orange-colored
spots parallelly arranged in elytra. All
patches on each elytron are mirror images of other elytron. The first three dark orange patches are
interconnected and other two are distinct (Image 3A). Head capsule is dark orange black colored with clypeus and frons testaceous. Elytron contains numerous punctures, a coarse
puncture line pass through the middle of elytra in antero-posterior
direction. Ventral surface is
predominantly black with distinct organization of appendages (Image 3B).
Structure: Large black color compound
eye and cranium, not emarginated; scutellum clearly visible with elytra
closed. Filiform antennae and
antennomeres 11 (Image 3C); posterior margin of pronotum elevated with dark
orange colored mark.
Pronotum without lateral bead. In
ventral part, distinct prosternal process and discrimen; elytral epipleuron
ends in 4th ventrites. Well distinct metatibial spur with numerous
long setae present. Ventral surface of
pro- and meso-tarsomeres broadly expanded into
rounded palette with ventral adhesive setae; male median lobe symmetrical,
protected by numerous spurs. Protarsi distinctly pentamerous, tarsomere
IV is smaller than the others (Image 3C).
Apices of both metatibial spurs bifid; series of bifid setae on
posterior surface of metatibia oblique.
Margins of sternites 6 & 7 are somewhat
bordered. Mesotibiae
with four natatorial setae (Image 3C); metatibiae is found without natatorial
setae (Image 3D).
Female:
Unknown
Diagnosis: This species shows close relation with Sandracottus dejeani
Aube, 1838 except in the case of presence of head with fine microreticulation and numerous small setiferous
punctures.
Distribution: Known only from the type locality.
Etymology: The species is named in honor
of Mr. Vijayakumar PK (Aka. Vijayakumar Blathur), Popular science writer in Malayalam for his
ardent passion towards insects.
Ecology: Most
of the seven specimens of Sandracottus vijayakumari sp. nov. were
collected in a partly shaded, shallow, ditch-like forest pool which was rich in
decaying leaves and twigs; lentic habitat.
Discussion
Dytiscinae contains five tribes, and 12 genera in total. These are among the largest of all diving beetles
in the world. They are characteristic of
pond and lakes, but they can be found in different ecosystems, with extensive
marginal vegetation. Many of the largest
have been involved in predation on vertebrates, some of them may rarely act as
competition in fish farming (Wilson 1923; Bishat
& Das 1979, 1985; Balke & Hendrich
1996; Adeyemo et al. 1997; Megna et al. 2019). In each biogeographic region, there are
groups of Dytiscinae with main groups that are
endemic to certain areas. They are well
distributed in temperate and high altitude to tropical low land habitats
(Miller & Bergsten 2014).
Until now, one species of Sandracottus
was known, i.e., S. dejeani Aube,
1838 from Silent Valley National Park, southern Western Ghats, Kerala, in 1979
(Mukherjee & Sengupta 1986). Sandracottus vijayakumari
sp. nov. shows a high similarity with the other
tribes, however, analyzing the morphological
taxonomic characters of this species shows close affinity to the tribe Aciliini. The strong
resemblance between the two species (S. vijayakumari
and S. dejeani) can be explained by
the multiple convergence arising from a similar shift in habitat. Throughout most biogeographical regions, Aciliines are found worldwide with distinct fauna and
sometimes uncommon genera, with the exception of Australia, where Aciliines comprises rare species of Sandracottus
and the extremely common Rhantaticus congestus (Klug, 1833) (Balke
& Hendrich 1996).
Historically, Dytiscinae has
been placed under Cybistrinae, which share a number
of synapomorphies in both adult and larvae (Alarie et
al. 2011; Miller & Bergsten 2014).
The tribe Aciliini may act as connecting link
between other diving beetles. The new
species S. vijayakumari, may play a
vital role in the evolutionary lineage of Dytiscinae. Ribera et al. (2002 & 2008) suggested
that either Eretesor Nottaticusis
nested within Aciliini, but the current evidence
shows that Eretini is sister to Aciliini (Bukontaite et al. 2014)
and Aubehydrini (Notaticus)
is sister to that clade (Miller & Bergsten 2014). Sandracottus
showed synapomorphy together with several other taxa such as Eretini, Hydaticini, and Aubehydrini, especially in the case of both metatibial
spurs are apically bifid. Also, the line
of bifid setae on the posterior surface of the metatibia is distinctly oblique
with resected to the long axis of the tibia.
More molecular and evolutionary studies are needed to assess the
evolutionary origin and diversification of these taxa, and S. vijayakumari will help to the understand the
convergent or divergent evolutionary pattern of Sandracottus
genus. In past few years nobody
studied the genus, and this genus is currently under revision (Miller &
Bergsten 2014).
Conclusion
Sandracottus vijayakumari sp. nov. shows close morphological similarity with S. dejeani; however the latter is from Silent Valley,
which is north of the Palghat gap of the Western Ghats, where
as the new species is from south of the Palghat gap.
Key to genera (Miller &
Bergsten 2016)
1 Mesofemur with longer ventral setae, at least some as long
as ½ x width of mesofemur; body length greater
(11.0–15.5 mm) …………………………………………………………….... Sandracottus
Sharp, 1882
1’ Mesofemur with shorter ventral setae,
less than ¼ x width of mesofemur; body length shorter
(7.5–11.0 mm) ……………………………………..……………............………………………
Rhantaticus Sharp, 1880
Key to species (modified from
Miller & Bergsten 2016)
The new species Sandracottus vijayakumari
sp. nov. is morphologically similar to S. dejeani Aube, 1838.
1 Head
being reddish-yellow; posterior border of vertex black; head without fine microreticulation and setiferous
punctures; pronotum with a few black and comparative coarse puncture; elongated
protarsus with adhesive disc without distinct spur; meso and meta tarsomeres have
series of golden setae along the apical
margins; dorsal elytra darkish orange patches largely separated and connect by
narrow bridges …………………………………………………………… Sandracottus dejeani
Aube, 1838.
1’ Head dark black with yellowish patch; Head with fine microreticulation and numerous small setiferous
punctures; pronotum and elytra with well distinct punctures and presence of
longitudinal punctures (Image 3a); protarsus expanded
and rounded suckers with distinct spur, adhesive disc (Image 3c); Meso and meta tarsomeres with a
series of black setae along the apical margins (Image 3c,d). The dorsal elytral darkish-orange patches are
distinctly separated from each other (Image 3a) ………………………………………………………………………………… Sandracottus vijayakumari
sp. nov.
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