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Cheleion watanabei sp. n., a new species of Stereomerini (Coleoptera, Scarabaeidae, Aphodiinae), and description of the male of C. jendeki
expand article infoShowtaro Kakizoe§, Munetoshi Maruyama, Kimio Masumoto|
‡ Kyushu University, Fukuoka, Japan
§ Japan Society for the Promotion of Science, Tokyo, Japan
| Unaffiliated, Tokyo, Japan
Open Access

Abstract

Cheleion watanabei sp. n. is described from Pahang, Peninsular Malaysia and represents the third species of the genus Cheleion Vårdal & Forshage, 2010 (Coleoptera, Scarabaeidae, Aphodiinae, Stereomerini). A description of the previously unknown male of C. jendeki Král & Hájek, 2015, and a key to the species of the genus Cheleion are also provided.

Keywords

Aphodiines, new species, Oriental region, Peninsular Malaysia, Southeast Asia, taxonomy

Introduction

The aphodiine tribe Stereomerini was established by Howden and Storey (1992) based on the genus Stereomera Arrow, 1905, from Singapore. Currently, 9 genera and 22 species from the Oriental and Australian regions are recognized in Stereomerini (Howden and Storey 1992, 2000; Bordat and Howden 1995; Storey and Howden 1996; Maruyama 2009; Vårdal and Forshage 2010; Maruyama and Nomura 2011; Král and Hájek 2015). The Oriental species are known to be extremely rare; all of them are known from single or a few specimens collected so far. Therefore, the males are rare and consequently most entomologists have avoided dissection of the genitalia; male genitalia of Stereomerini have been described only for two Australian species (Howden and Storey 1992; Storey and Howden 1996). Recently we examined two Stereomerini specimens from Peninsular Malaysia: one was found to be a female of an undescribed species belonging to the genus Cheleion and the other was identified as a male of Cheleion jendeki Král & Hájek, 2015. The description of the new species and the previously unknown male of C. jendeki as well as a key to the species of Cheleion are provided herein.

Materials and methods

All specimens were dried and mounted on paper cards for morphological observation; dissected genitalia were mounted in Euparal on a small glass plate (10×5 mm), and subsequently glued onto a paper card (6×5 mm) and pinned under the specimen (Maruyama 2004). Specimen photographs were taken with an Olympus OM-D E-M1 Mark II with a Canon MP-E 65 mm 1–5× macro lens and KIPON EF-MFT AF adapter for Figures 16, with a Canon EOS 7D Mark II with a Mitutoyo M Plan Apo 20× and a Raynox DCR-150 for Figures 8–11, and subsequently stacked using CombineZP software. Images were edited using Adobe Photoshop CS6. Terminology of the species description follows Howden and Storey (1992), Vårdal and Forshage (2010) and Král and Hájek (2015).

Taxonomy

Cheleion watanabei Kakizoe, Maruyama & Masumoto, sp. n.

Figs 1–4, 9, 11

Type material

Holotype, female, deposited in the National Museum of Nature and Science, Tsukuba, Japan: “PENINSULAR MALAYSIA, Pahang, Cameron Highlands, Tanah Rata, 8–12. III. 2006, T. Watanabe leg., by FIT [= flight interception trap]”.

Distribution

(Fig. 12) Peninsular Malaysia, Pahang, Cameron Highlands, Tanah Rata.

Etymology

Dedicated to Mr Takashi Watanabe, the collector of the type specimen.

Diagnosis

This new species is easily distinguished from all known congeners by the following character states: 1) larger body size (total body length ca. 2.5 mm); 2) anterior ridges of the two distinct pronotal depressions short; 3) pads bearing lanceolate scale on the elytra slightly developed; 4) elytral posterior margin strongly depressed; and 5) elytral ridges indistinct.

Description

Holotype female. Large species (2.51 mm). Body (Figs 1–4) slightly convex dorsally, dorsal surface more or less covered with appressed lanceolate scales, general color uniformly matte brown. Head (Figs 1–4) wide, subrectangular in dorsal view, with densely appressed lanceolate scales. Clypeus impunctate, shiny, apically pointed and reflexed under head. Frons flat with five anteriorly divergent furrows, second and fourth furrows strongly curved medially. Genal tip slightly obtusely angular in dorsal view. Eyes large, visible ventrally, less visible dorsally. Occiput with numerous small, longitudinal punctures. Antennae long, amber colored, with long setae; club lamellae long. Maxillary palpi as long as head, amber colored, with securiform ultimate palpomeres. Prothorax (Figs 1–4) large and transverse, anterior edge slightly bisinuate, side edges weakly rounded in dorsal view. Base of pronotum with a median protrusion, wider than base of elytra. Pronotal disc with seven furrows medially, concave at middle of hourglass pattern, with tufts of dense trichomes, with densely appressed lanceolate scales; mid furrow shallower than lateral furrows. Lateral furrows large, flat. Subtriangular depressions delineated by more furrows sparsely appressed lanceolate scales medially. Anteromedial disc distinctly high, tuberculate; promedial disc and posterolateral sides slightly low, less tuberculate than anteromedial disc. Prosternum fairly elevated and expanded anteriad and posteriad, rugose; anterior part grooved longitudinally and sinuate apically, posterior part hastate; prosternal spine apically pointed. Scutellum (Figs 1, 3, 4, 9) triangular, notably small. Elytra (Figs 1–4, 9, 11) approximately as wide as pronotum and only slightly longer than pronotum and head combined; feebly tapered posteriad, fairly rounded apically; posterior margin strongly depressed. Each elytron with three indistinct ridges; intervals (between ridges) flat, rugose, with densely appressed lanceolate scales. Epipleura broadly inflexed; posterior two-thirds of lateral edge slightly recurved to allow free movement of metalegs. Macropterous. Mesoventrite (Fig. 2) strongly narrow with alutaceous and punctured surface. Metaventrite (Fig. 2) flat, alutaceous, subtriangular, tapering, widest anteriorly, grooved along midline, with coarse, macrosetigerous punctures. Legs (Figs 1–4) short with broad femora and tibiae. Femora shiny, covered with coarse, macrosetigerous punctures. Protibiae flattened; each with two teeth on outer edge, sparsely macrosetose outward. Protarsi pentamerous, amber colored, long, sparsely macrosetose medially, inserted well before protibial apex. Proclaws normal, symmetrical. Meso- and metatibiae with concave, sparsely macrosetose apex; each with five inconspicuous terminal spurs; dorsal sides shiny, glabrous; ventrolateral sides with densely appressed lanceolate scales. Meso- and metatarsi tetramerous, short, compacted-complanate, sparsely macrosetose medially. Meso- and metaclaws slightly weak, symmetrical. Abdomen (Fig. 2) with five visible ventrites apparently fused, covered with coarse, dense, macrosetigerous punctures. Pygidium exposed, strongly punctate proximally, less strongly apically.

Figures 1–4. 

Habitus of Cheleion watanabei sp. n. (♀ holotype) 1 dorsal view (anterior ridge of pronotal depression arrowed) 2 ventral view 3 dorsolateral view 4 anterodorsal view.

Male. Unknown.

Measurements

Body length 2.51 mm; maximum width of head 0.79 mm; median dorsal length of pronotum 0.74 mm, maximum width 1.16 mm; sutural length of elytra 1.15 mm, maximum length 1.26 mm, maximum width 1.22 mm.

Cheleion jendeki Král & Hájek, 2015

Figs 5–7, 8, 10

Cheleion jendeki Král & Hájek, 2015: 88 (original description based on a female).

Material examined

PENINSULAR MALAYSIA, Pahang, near the gate of Taman Negeri Endau Rompin, alt. 30 m, 8–23. III. 2015, S. Kakizoe, K. Hoshino, S. Kakinuma & H. Osaki leg., by FIT, 1 ex. male.

Additional description based on male

Legs (Figs 5, 6). Protarsi pentamerous, amber colored, long, sparsely macrosetose medially, inserted well before protibial apex. Aedeagus (Fig. 7). Symmetrical. Phallobase elongate, cylindrical. Parameres short, almost a quarter length of basal piece. Phallus a little longer than parameres, rounded apically. Struts long, almost two-thirds length of tegmen.

Figures 5–7. 

Habitus of Cheleion jendeki (♂) 5 dorsal view (anterior ridge of pronotal depression arrowed) 6 dorsolateral view 7 Aedeagus in dorsal view.

Sexual dimorphism

No sexual dimorphism detected.

Measurements

Body length 1.80 mm; maximum width of head 0.67 mm; median dorsal length of pronotum 0.61 mm, maximum width 0.94 mm; sutural length of elytra 0.92 mm, maximum length 0.96 mm, maximum width 0.92 mm.

Remarks

No males were known for the genus Cheleion so far, therefore a description of the male of C. jendeki is provided here. Furthermore, Král and Hájek (2015) reported that the tarsal formula for C. jendeki was 4-4-4, but it is actually 5-4-4. Therefore, the tarsal formula of C. malayanum given by Vårdal and Forshage (2010) is probably also inaccurate.

Figures 8–11. 

Comparison of scale between Cheleion jendeki and C. watanabei sp. n. 8, 10 C. jendeki (♂) 9, 11 C. watanabei sp. n. (♀ holotype) 8, 9 base of right elytron 10, 11 posterior part of right elytron.

Figure 12. 

Distribution map of Cheleion species: black star C. watanabei sp. n., black circle C. malayanum, black triangle C. jendeki.

Key to the species of the genus Cheleion

1 Large (2.5 mm); anterior ridges of two distinct pronotal depressions short (Fig. 1, arrowed); elytral ridges indistinct, each pad bearing slightly-developed lanceolate scales, densely appressed on elytra; elytral posterior margin strongly depressed C. watanabei sp. n.
Small (1.8–1.9 mm); anterior ridges of distinct pronotal depressions long (Fig. 5, arrowed); elytral ridges distinct, each pad bearing well-developed lanceolate scales, moderately appressed on elytra, elytral posterior margin not or feebly depressed 2
2 1st and 5th divergent furrows on head weakly s-shaped; distinct pronotal depressions small, subtriangular; prosternal spine apically pointed; elytral ridges broad, most pads bearing lanceolate scale confluent to subconfluent C. malayanum Vårdal & Forshage, 2010
1st and 5th divergent furrows on head straight; distinct pronotal depressions large, subrectangular; prosternal spine apically not pointed; elytral ridges narrow, most pads bearing lanceolate scale separated C. jendeki Král & Hájek, 2015

Acknowledgements

We wish to express our cordial thanks to Mr Takashi Watanabe (Kanagawa Pref., Japan) for kindly providing the material, Dr Andrey Frolov (Universidade Federal de Mato Grosso), Dr Marco Dellacasa (Museo di Storia Naturale e del Territorio dell’Università di Pisa) and Dr David Král (Charles University) for critically reading the manuscript, Mr Konosuke Hoshino (Nagaoka Municipal Science Museum), Mr Shunsuke Kakinuma (Tokyo University of Agriculture and Technology), Ms Haruka Osaki (Kyushu University) for their kind assistance in the field survey and to Dr Rosli Hashim (University of Malaya) for his kind support in the field survey by SK, Mr Hoshino, Mr Kakinuma and Ms Osaki. This work was partially supported by a Grant-in-Aid for JSPS Fellow (17J07016) to SK from the Japan Society for the Promotion of Science, Japan.

References

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