Research Article |
Corresponding author: David Král ( kral@natur.cuni.cz ) Academic editor: Frank Krell
© 2015 David Král, Jiri Hajek.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Král D, Hájek J (2015) A second species of Cheleion from Johor, Malaysia (Coleoptera, Scarabaeidae, Aphodiinae, Stereomerini). ZooKeys 532: 87-97. https://doi.org/10.3897/zookeys.532.6116
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A new species of the genus Cheleion Vårdal & Forshage, 2010, Cheleion jendeki sp. n., from Johor, Malaysia is described, illustrated and compared with the type species of the genus, C. malayanum Vårdal & Forshage, 2010. Photographs of the two species are presented. The adaptation to inquilinous lifestyle of Cheleion is compared with those in other beetle groups and briefly discussed.
Cheleion , new species Coleoptera, Scarabaeidae , Aphodiinae , Stereomerini , Malaysia, Oriental Region
Scarabaeoidea (Lamellicornia) represent a distinct, cosmopolitan group of beetles, comprising approximately 2,500 genera and 35,000 species worldwide. They occupy a vast range of various niches, including inquilinous, either myrmecophilous or termitophilous, lifestyles (for a review, see
The specimens were examined with an Olympus SZ61 stereomicroscope. Measurements were taken with an ocular graticule. The habitus photographs were taken using a Canon MP-E 65mm f/2.8 macro lens with 5:1 optical magnification on bellows attached to a Canon EOS 550D camera. Partially focused images of specimen were combined using Helicon Focus 3.20.2Pro software. External morphology of both species was also examined with a Hitachi S-3700N environmental electron microscope in the Department of Paleontology, National Museum in Prague (in both cases using uncoated specimens). Exact label data are cited for the type material. Our remarks and addenda are found in brackets, separate label lines are indicated by a slash (/), separate labels by a double slash (//). The holotype of the newly described species is deposited in the collection of
Malaysia, Johor, Endau Rompin National Park, 02°37'12"N 103°21'00"E, 120–300 m a. s. l.
Holotype: ♀, “Malaysia, Johor / Endau Rompin NP / N2.62, E103.35 / 28-31.v.2013, 120-300 m / E. Jendek & O. Šauša leg. [printed] // Cheleion jendeki sp. nov. / HOLOTYPUS ♀ / David Král & Jiří Hájek det. 2015 [red, printed]”.
Slightly convex, integument chestnut brown; head appendages and tarsi amber coloured; whole dorsal surface more or less covered with appressed lanceolate scales (Fig.
Head (Figs
Pronotum (Figs
Details of Cheleion. 15, 17 C. malayanum (♀ holotype; Malaysia, Pahang, Bukit Fraser) 13–14, 16, 18 C. jendeki sp. n. (♀ holotype) 13 detail of tufts of microtrichiae (= trichomes) in centre of pronotum 14 detail of macrosetation on elytral shoulder 15–16 head and prosternum in ventral view 17–18 meso- and metaventrite in ventral view.
Scutellar shield triangular, notably small (Fig.
Elytra approximately as broad as pronotum and only slightly longer than pronotum and head combined; tapering posteriad, rounded apically. Each elytron with five longitudinal ridges before the lateral edge (Figs
Legs short with broad femora and tibiae; tarsi short, tetramerous; claws weak, short, almost straight (Figs
Macropterous.
Pygidium exposed, strongly punctate proximally, less strongly apically, with small emargination on proximal pygidial border.
Venter. Prosternal process remarkably elevated, strongly expanded anteriad and posteriad (Figs
Five visible abdominal ventrites apparently fused, covered with coarse, dense, almost regularly spaced macrosetigerous punctures.
Total body length: 1.9 mm, width at broadest point 0.9 mm.
The new species is classified in the genus Cheleion mainly by the combination of the following characters: strongly tuberculate and rugose body surface, noticeably long antennae, pronotum with distinct anteromedial knob and bulbous areas medially and laterally and hastate posterior prosternal process. Cheleion jendeki sp. n. is similar and probably closely related to C. malayanum, the only other known species of the genus, but clearly differs mainly as follows:
lateral longitudinal grooves on head straight (Figs
sides of pronotum regularly rounded, maximum width of pronotum in midlength; posterior angles subrectangular (Figs
elytral surface at first sight moderately rugose (Figs
elytral ridges distinctly elevated (Figs
elytral ridges continuous, consisting of longitudinal rows of almost confluent tubercles; lateral ridges indistinct (Fig.
pads on elytral intervals separated by less their diameter and mostly arranged as triseriate discally (Fig.
marginal bead of posterior part of prosternal process rounded apically (Fig.
In spite of clear differences mentioned above, we are aware that only single specimens are known for each Cheleion species. In addition, both type localities are placed only about 200 km apart, without any distinct barrier between them. Thus, we cannot exclude the possibility that morphological differences of C. jendeki sp. n. represent only an intraspecific variability of C. malayanum, but we consider it quite improbable.
Patronymic; named in honour of our colleague and friend Eduard Jendek (Ottawa, Canada), excellent student in Buprestidae and collector of the holotype.
So far known only from the type locality in the Johor Province of continental Malaysia.
Virtually nothing is known about the biology of Stereomerini. Beetles were repeatedly supposed to be termitophilous, based on single finding of Termitaxis holmgreni Krikken, 1970 with termites in Peru (
We have not been able to trace any “typical characters” distinguishing myrmecophilous and termitophilous beetles. For example,
There exist numerous well known myrmecophilous aphodiines, especially of the tribe Eupariini (see, e.g.,
In rather rare cases of presence of trichomes in termitophilous scarabaeids, those structures are not recorded from the pronotum and have a quite different appearance from Cheleion (see, e.g.,
The peculiar structure on the pronotum in Cheleion, consisting of a central pit surrounded by numerous long microtrichia (= trichomes), is surprisingly similar to the pronotal structure of myrmecophilous ptinids (see, e.g.,
We thank Johannes Bergsten (