Rare fungus feeding
Darkling Beetle, Byrsax cornutus Fabricius, 1792 (Coleoptera: Tenebrionidae: Bolitophagini)
from the Western Ghats, India
C. Arunraj1, Sabu K. Thomas 2 & Ottó Merkl 3
1,2 Litter Entomology Research
Unit, Post Graduate and Research Department of Zoology, St. Joseph’s College, Devagiri, Kozhikode, Kerala, India.
3 Hungarian Natural History
Museum, Baross utca 13,
H-1088 Budapest, Hungary.
1 rajcarun@gmail.com, 2 sabukthomas@gmail.com
(corresponding author), 3 merkl@zoo.zoo.nhmus.hu
doi: http://dx.doi.org/10.11609/JoTT.o3188.4608-11 | ZooBank:urn:lsid:zoobank.org:pub:16CD19AE-C3F0-45E0-84E0-1BD52929B718
Editor: Dr. Partha Pratim Bhattacharjee,
Tripura University, Suryamaninagar, India Dateof publication: 26 July 2013 (online & print)
Manuscript details: Ms #
o3188 | Received 01 May 2012 | Final received 27 June 2013 | Finally accepted
02 July 2013
Citation: Arunraj,
C., S.K. Thomas & O. Merkl (2013). Rare fungus feeding Darkling Beetle, Byrsax cornutus Fabricius,
1792 (Coleoptera: Tenebrionidae:Bolitophagini) from the Western Ghats, India. Journal
of Threatened Taxa 5(11): 4608–4611; http://dx.doi.org/10.11609/JoTT.o3188.4608-11
Copyright: © Arunrajet al. 2013. Creative Commons Attribution 3.0 Unported License. JoTTallows unrestricted use of this article in any medium, reproduction and
distribution by providing adequate credit to the authors and the source of
publication.
Funding: Department of Science and
Technology, Government of India (DST-INSPIRE Fellowship)
Competing Interest: None.
Acknowledgements: Financial
assistance provided by Department of Science & Technology (DST), Government
of India (DST-INSPIRE Fellowship) to the first author is gratefully
acknowledged. We thank T. Németh, expert on HungarianElateridae, Hungarian Natural History Museum for
digital images, and P.M. Nirdev, St. Joseph’s
College, Kozhikode, for assistance during field trips.
The publication of this article is
supported by the Critical Ecosystem Partnership Fund (CEPF), a joint initiative
of l’Agence Française de Développement, Conservation International, the
European Commission, the Global Environment Facility, the Government of
Japan, the MacArthur Foundation and the World Bank.
Beetles of the tribe Bolitophagini are associated with fruiting bodies (conks)
of bracket fungi throughout their lives. The larvae always tunnel inside the conk and feed on its tissue while
adults usually are surface feeders; consuming the spores after sweeping them
with their mouthparts to the mouth. The adults are mainly seen on the surface of the hymenium (the fertile
layer of the fruiting body), although some species hide in the larval tunnels
during the day. Bolitophaginesusually feed on the same fruiting body associated with dead trees and develop
in it until the fungi are completely destroyed and decayed (Jung et al.2007).
Members of a genus of the
tribe, Byrsax, live in the fruiting
body of various bracket fungi, including the wood-decaying white-rot bracket
fungus Ganoderma applanatum (Persoon) Patouillard1889, popularly known as Artist’s Conk (Hawkeswood2003).
Distribution of the genus
stretches across the Palaearctic (Russian Far
East, Japan, Korea, China), Oriental (India, Sri Lanka, Vietnam,
Indonesia, Malaysia, Philippines) and Australian (eastern Australia, Papua New
Guinea) realms (Gebien 1939; Kaszab1979a,b, 1980; Jung et al. 2007; Löbl et al.
2008; Matthews & Bouchard 2008). Cryptic brownish-grey coloration of
adults that matches the color of host fungi and secretive habits of Byrsax species lead them to be often overlooked by
collectors (Hawkeswood 2003). Twenty sevenspecies of the genus Byrsax are known
worldwide (Gebien 1939; Löblet al. 2008). Two species namely, Byrsax cornutus Fabricius, 1792 (Gebien1925) and B. tuberculatus Gravely, 1915 (Kaszab 1979a) are reported from India (Image 1). Byrsax tuberculatus(Image 2) is known to occur in Nepal, India (Arunachal Pradesh, Kerala: Kumily), Sri Lanka (Colombo, Peradeniya,
Kandy, Dikoya, Kitulgala, Galle),
Thailand, Vietnam, Malaysia, Java, Borneo and the Philippines. Byrsax cornutus occurs in India and Sri Lanka (Image 1). The present work includes a first report
of Byrsax cornutusfrom the Western Ghats with diagnostic description, key to the two Byrsax species from India along with an illustration
of their distribution from the Indian subcontinent.
Materials and Methods: Specimens were collected with
light traps and from leaf litter present close to a decaying log with rich
growth of Ganoderma applanatumduring 2006–2009 period. Identification up to the genus and species level was done with the key
of Gebien (1925) and by comparing with verified
specimens in the Coleoptera Collection of the
Hungarian Natural History Museum, Budapest, Hungary. Specimens from the present study
are deposited in the coleopteran collections of Litter Entomology Research
Unit, St. Joseph’s College, Devagiri, Calicut (SJC).
Byrsax cornutus (Fabricius,
1792)
(Image 3)
Synonyms: Byrsax horridus Olivier, 1795; Byrsax tuberculifer Motschulsky,
1863 (Gebien 1925).
Materials Examined: BC-2009-01 SJC, 22.vii.2009, one female, Omassery,
Kerala, India (11.36660N & 75.93330E; 22m elevation),
light attracted specimen, coll. C. Arunraj (Image 3);
BC-2006-02 SJC, 06.xii.2006, one male, Malaparamba(11.30000N & 75.85000E; 13m elevation), litter
collection, Berlese extraction, coll. K.V. Vinod.
Body: Oval, strongly convex, strongly sculptured and tuberculate. usually covered with
lighter brown encrustation of fungal spores. Spore mass usually filling and obscuring
dorsal punctation of pronotumand elytra.
Color: Blackish-brown.
Head: Frons
of male with a pair of curved and flattened horns; length of horn varying from
shorter than interocular distance to as long as
length of pronotum. Female without horns. Eyes large, oval, excised by frontal
canthus. Labrum subquadrate, setal pattern
symmetrical, antennae barely longer than head width, antennomeresgradually expanding apically, last seven antennomeresforming a large asymmetrical club. Mandibles bidentate with
long teeth, molar surface with fine striations. Maxilla without lacinial uncus, palpi with apical segments fusiform. Mentumtrapezoidal.
Pronotum: Surface with coarse punctation and with strong protuberances and tubercles
varying in size, lateral parts strongly explanate,
sides strongly serrate, with a semicircular excision near posterolateralangles.
Elytra: Highly
convex, with coarse punctation and strong
protuberances and tubercles. Three protuberances on each elytron much larger and arranged in two
parallel rows, other tubercles much smaller. Lateral parts strongly explanate, sides strongly serrate.
Venter: Procoxal cavities closed internally and externally. Mesocoxal cavities partly closed by mesepimeron. Membranes present between last three
abdominal ventrites.
Legs: Notfossorial, tibiae with longitudinal carinae, subapical tarsomeres very short, obliquely truncate, plantar surfaces
with long sparse setae. Tarsal formula 4-4-4 (in contrast
with 5-5-4 as normal in the family Tenebrionidae).
Measurements (in mm; 1 male and 1 female): TL = 6–6.2, TW =
2.6–2.9, PL = 2.5–2.8, PW = 1.9–2.1, EL = 4.2–4.4.
Habitat: On
fruiting bodies of bracket fungi, also leaf litter around them; attracted to
light.
Distribution: India (Kerala: Kozhikode; Pondicherry); Sri Lanka (Colombo, Kantalai, Rajakadaluwa, Puwakpitiya, Uggalkaltota,
Galle). Occurrence in Sumatra (Gebien 1925) is
doubtful.
Remarks: Byrsax cornutus is active after sunset.
During the day it remains motionless, but starts walking upon exposure to
sunlight to find shelter. On handling it produces a very strong, distinctive odour caused by the secretion of abdominal defensive
glands.
Dorsal surface of the beetle
is strongly sculptured and tuberculate, and capable
of holding a compact layer of spores of the host fungi. This, along with the
body form, provides a perfect camouflage; the motionless beetle looks like a
simple hump and is very hard to recognize in its environment of rugged fruiting
bodies and parts of rotten wood.
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