Taxonomy of Onthophagus javanensis and its closest relatives in Sundaland (Coleoptera: : )

J. Huijbregts & J. Krikken

A group of closely related scarab taxa around Onthophagus javanensis Balthasar, 1959 is redefined, and its ten Sundaland members are keyed, diagnosed, and illustrated. For Onthophagus javanus Lansberge, 1883 (non Fabricius, 1801, accepted replacement name O. javanensis Balthasar, 1959) a lectotype is designated to consolidate species delimitation. Five new species are proposed: O. allojavanus (Sumatra), javanoides (Sumatra, Malay Peninsula), clivimerus (Borneo), peninsulomerus (Malay Peninsula), and leusermontis (Sumatra, Malay Peninsula, Singapore); additionally, O. javanensis aberratio palavanus Balthasar, 1959 (unavailable name) from Palawan (Philippines) is raised to species rank and redescribed. The male of O. ochromerus Harold, 1877 is formally recorded for the first time. New records are given. The position of the javanensis group of species in the subgenus Paraphanaeomorphus Balthasar, 1959 is disputed. J. Huijbregts, Netherlands Centre for Biodiversity Naturalis, PO Box 9517, 2300 RA Leiden, The Netherlands. [email protected] J. Krikken, Netherlands Centre for Biodiversity Naturalis, PO Box 9517, 2300 RA Leiden, The Netherlands. [email protected]

Introduction The species are all very similar, and identifications Several dung species from Sundaland are in collections and publications show that their inter- attributable to what is here called the javanensis specific delimitation currently is insufficient. One operational group in the scarab genus Onthophagus cannot, for instance, be certain of records of javan- Latreille, 1802. Male members of this group are ensis outside Java (as, for instance, given in Balthasar characterized by having only one simple ridge on 1963), and reported variation may concern different their head, which may be developed into a higher species. transverse, dentiform plate; both sexes have a con- This study aims to improve the delimitation of the spicuous shining, glabrous area in either posterola- Sundaland species in the javanensis group, while teral corner of their pronotum, lined by long, stiff showing that their is more intricate than setae. Members of this javanensis group have been hitherto thought. It is another instalment in our collected mainly by baited pitfall trapping in forest ongoing series on scarabaeine and other dung bee- environments, from sea level up to about 1700 m tles of the Southeast Asian islands, from the Malay altitude. Peninsula to New Guinea, intended to eventually The group, comprising the name-giving O. javan- result in a synopsis. With hundreds of congeneric ensis Balthasar, 1959 and ten more described and species known to us, Onthophagus definitely is the undescribed relatives, is further defined by the set of dominant genus in the region, and obviously many characters given immediately after this Introduction. additions are anticipated.

Tijdschrift voor Entomologie 154: 33–59, Table 1. Figs 1–77. [ISSN 0040-7496]. http://www.nev.nl/tve © 2011 Nederlandse Entomologische Vereniging. Published 1 June 2011. 34 Tijdschrift voor Entomologie, volume 154, 2011

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7 8 Figs 1-8. Habitus, oblique view of males, with approximate specimen length. – 1, Onthophagus javanensis (W Java) 7.5 mm; 2, allojavanus (holotype) 8.5 mm; 3, javanoides (holotype) 8 mm; 4, waterstradti (Sabah) 7.5 mm; 5, palavanus (holotype) 8.5 mm; 6, ochromerus (Sabah) 9 mm; 7, leusermontis (holotype) 8 mm; 8, lindaae (para- type) 7.5 mm.