Rediscovery and redescription of Dilobitarsus pendleburyi (Coleoptera, Elateridae, Agrypninae) from Southeast Asia

Abstract Dilobitarsus pendleburyi Fleutiaux, 1934 is recorded for the first time after its original description and is redescribed. This represents the first record from the Malay Peninsula, Malaysia and Sumatra, Indonesia. The systematic position of this species is discussed.


Introduction
The genus Dilobitarsus Latreille, 1834 is represented by 32 species belonging to Agrypnini. Among them, 31 species are distributed in the New World, and only one species D. pendleburyi Fleutiaux, 1934 is found in the Oriental region (Casari 2013). Almost all species are known only from their original descriptions, and their genitalia and mouthparts are not described (e.g., Candèze 1857;Schwarz 1902;Fleutiaux 1907). Hayek (1973) reviewed this genus by examining type and non-type specimens, but did not find some type specimens (perhaps lost), or include species descriptions or illustrations. Casari (2013) described four new species in detail including descriptions of the genitalia and mouth parts. She provided a key to the New World species. This research improved our understanding of the morphology of Dilobitarsus. Fleutiaux (1934) described Dilobitarsus pendleburyi from a male specimen from Borneo, Malaysia. No subsequent records or information have been published. I examined the type specimen of this species and additional specimens including a male from the Malay Peninsula, Malaysia and a female from Sumatra, Indonesia. This paper redescribes this species, and presents new distributional records from the Malay Peninsula and Sumatra. The systematic position of this species is discussed.

Materials and methods
The type specimen is deposited in the Natural History Museum, London (BMNH). Non-type specimens examined are in the personal collection of Kôichi Arimoto and Hisayuki Arimoto (CAR; Osaka, Japan).
Photographs of specimens were taken using a single-lens reflex camera (Canon EOS 7D) with a macro lens (Canon macro photo lens MP-E 65-mm) and combined using image processing software (CombineZM, Alan Hadley).
The morphology of specimens was observed under a stereo microscope (Olympus-SZX9). Measurements are in millimeters and were made with a micro ruler (MR-2, minimum scale value: 0.05 mm, Kenis Limited, Ôsaka, Japan) to obtain the following properties: body length from apex of the head to apices of the elytra (BL), body width (BW), pronotum length including posterior angles (PL), length of the midline of the pronotum (PML), pronotum width including posterior angles (PW), elytra length (EL), and elytra width (EW). Non-type specimens were used for dissection. The mouth-parts, pregenital segments and genitalia were soaked in 10% KOH solution (room temperature, male: 2 hours, female: 30 hours). The parts were dehydrated in 99.5% ethanol (5 min) and then mounted in euparal on a microscope slide, except for mounting of the bursa copulatrix in glycerin. A transmission microscope (Nikon Y-IDT) attached to a drawing device was used for observations of the dissected parts and creation of line drawings. Morphological terminology follows Calder (1996), and Casari (2013) in part.
Maps were made using free software (DIVA-GIS 7.5.0.). The digital images of map, photographs and drawings were edited with image editing software (Adobe Photoshop 7.0).    Redescription. Adult. Body (Figs 2, 7, 8) elongate, convex; surface smooth, shining, with large punctures; black-brown to red-brown, but mouth-parts yellow-brown with mandible black-brown. Setae. Body covered with narrow scale-like setae; bases of tarsal claws each with a thick seta. Head and pronotal anterior part with orange setae; pronotum with black setae at the center, with white setae posteriorly; elytra with in- termixed white and black setae, together with white U-shaped setal apical band; setae at pronotal and elytral tubercles denser and erect; ventral surface with white setae, but abdominal ventrites partially with dense orange setae (Fig. 9).
Larvae and pupae. Unknown.
Remarks. This species is easily identified by its three-coloured setal pattern and tubercles of the pronotum and elytra.
Bionomics. Nothing is known about the life history.
Dilobitarsus and its species have been described from several continents based on this state (e.g., Candèze 1857). Schwarz (1902) Schwarz, 1902 andCandanius Hayek, 1973 because all share the all above character states except for ventral tarsal lobe, and they belong to the informal Dilobitarsusgenus group (here proposed). The genera of this group are characterized especially with antennomere III larger than II (Fig. 18) in Agrypninae. Although Dilobitarsus, Hemicleus Acrocryptus and Elasmosomus share ventral tarsal lobes, since this characteristic has been observed in many distant lineages of Elateridae, there is the possibility that it is homoplasy. Additionally, the degree of development of the ventral tarsal lobes varies between species. Future studies of the phylogenetic relationships in Agrypnini and Agrypninae are needed in order to determine whether the presence of ventral tarsal lobes represents homoplasy and to test the monophyly of the Dilobitarsus-genus group.
Dilobitarsus pendleburyi is characterized especially with V-shaped frontal margin and laterally high nasal plate (Figs 3,12). It is necessary to review the generic placement of this species. However there is not enough information about head status of the other species. Further reviews of the morphology of the species in this genus group are important to understand precisely the systematic position and apomorphies of D. pendleburyi.