The subfamily Aphodiinae Leach 1815 (Coleoptera: Scarabaeidae), commonly called as small dung beetles, consists of 3200 species within 280 genera in the world (Dellacasa, 1991;Kim, 2012). Most of Aphodiinae species are detritivores, inhabiting various habitats, and some species occur in nest of social insects such as ants and termites (Krikken and Huijbregts 1987;Kim, 2012;Parker, 2016). Among them, Rhyparini Schmidt is a representative tribe known as termitophilous group (Skelley, 2007;Vårdal and Forshage, 2010). This group can be distinguished by carinate dorsal surface, longitudinal costae in pronotum and elytra. Also, bulbous projection with trichomes on elytral apex can be diagnosis character of this tribe, except the genera Sybacodes and Megasybacodes (Pittino, 2006;Skelley, 2007;Kakizoe et al., 2019).
The genus RhyparusWestwood 1845, one of the 13 subordinate genera from the tribe Rhyparini, comprises 84 species and one subspecies worldwide (Ochi et al., 2021;Schoolmeesters, 2022). The nomenclature history of this genus is complicated and has led to various discussions. In 1843, Westwood proposed this genus, spelled ‘Ryparus’, but around the same time, Spinola also used identical spelling for a genus of Cleridae (see also Cartwright and Woodruff, 1969;Dellacasa, 1997). According to the effective publication date (Spinola, 1844;Westwood, 1845), Westwood's ‘Ryparus’ became junior homonym of Spinola's ‘Ryparus’. Later, Agassiz (1847) emended the spelling of the genus ‘Ryparus’ to ‘Rhyparus’ for the species Rhyparus desjardinsii Westwood. Smith (2006) stated that Rhyparus, Agassiz’s unjustified emendation, is considered a justified emendation by ICZN 1999 because of its prevailing usage. Therefore, this study accepted current opinion of Smith (2006) for the priority of Westwood rather than Agassiz.
So far, only one species of this genus, R. azumai Nakane has been announced in Korea (Choi et al., 2015;Lim and Bae, 2019) which recently elevated to species rank (Ochi et al., 2018). In this study, we record Rhyparus helophoroides Fairmaire in Korea for the first time. Diagnosis, photographs of diagnostic characters, key to the Korean Rhyparus, and brief ecological information of the species are provided.
Materials and Methods
Materials for the study were collected by white light trap in Jeju Island. Specimen examination was performed under a stereoscopic microscope (Nikon SMZ645). Male genitalia was dissected and placed in 10% KOH solution for 1 hour at 60℃ before examination. Photographs were taken using Nikon digital camera (Z7) with 70 mm Macro Lens (Nikon, Inc., Tokyo, Japan). The terminology used in the present study generally follows Krikken and Huijbregts (1987), and Anichtchenko et al. (2021). All materials are deposited in the National Institute of Biological Resources (NIBR; Incheon, South Korea) and Choi’s insect collection (CI; Seoul, South Korea).
Taxonomic Accounts
Family Scarabaeidae Latreille, 1802
Subfamily Aphodiinae Leach, 1815 똥풍뎅이아과
Tribe Rhyparini Schmidt, 1910 줄똥풍뎅이족
Genus RhyparusWestwood, 1845 줄똥풍뎅이속
Type species: Rhyparus desjardinsiiWestwood, 1845
Rhyparus helophoroidesFairmaire, 1893
작은줄똥풍뎅이(신칭) (Fig. 1)
Rhyparus helophoroidesFairmaire, 1893: 145.
Type locality. Bornéo occ.: Sambas; Java: Simpar et Kemanglen, rés. Tegal.
Diagnosis. Body length 3.5 - 4.0 mm, Body matt blackish brown. Head convex, lateral emargination moderate angular. Pronotum with two obtuse and rounded protrusions in lateral margin, anterior protrusions slightly smaller than median one; punctures irregularly distributed as a whole between the two middle ridges. Elytra elongate with large punctures of two longitudinal rows at each ridge; internal and median caudal indentation connected; external protrusion weakly developed. Aedeagus as in Fig. 1.
Materials examined. [NIBR] 1♂, South Korea, Jeju Island, Seogwipo-si, 20. VII. 2020, leg. M. Kim. [CI] 1♀, South Korea, Jeju Island, Seogwipo-si, 20. VII. 2020, leg. M. Kim; 1♀, South Korea, Jeju Island, Jeju-si, 12 - 14. VII. 2018, leg. J. Choi.
Distribution. Korea (new record), Australia, Bornéo, Indonesia, Japan, Malaysia, New Caledonia, Papua New Guinea, The Philippines, Taiwan, Vanuatu.
Remark. The specific epithet of this species was often erroneously described as ‘helephoroides’ (Löbl and Smetana, 2006;Choi et al., 2015). These errors probably came from typographical errors in the past study of Schmidt (1910), which was addressed by Mencl et al. (2013).
Key to The Species of the Genus Rhyparus in Korea
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1. Body length over 5 mm long. Lateral margin of pronotum with angled anterior protrusions ····································· ················································· R. azumai Nakane 1956
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- Body length under 4 mm long. Lateral margin of pronotum with rounded anterior protrusions ···································· ····································· R. helophoroidesFairmaire 1893
Ecology. The ecology of R. helophoroides is largely unknown. This species is mainly collected and observed through light traps, and sometimes collected by sifting leaf litter (Kawai et al., 2005;Okajima and Araya, 2012;Théry and Bordat, 2012). Likewise, in Korea, the species was only collected by light trap. The ecology of another relative species recorded in Korea, R. azumai, is also largely unknown in Korea and Japan except that individuals are collected by light trap (Kawai et al., 2005;Choi et al., 2015). So far, only a small number of individuals of both species have been observed in the southern region and Jeju Island in South Korea (Choi et al., 2015; personal observation). Kakizoe and Maruyama (2017) mentioned that Rhyparus species inhabiting Japan (including R. helophoroides and R. azumai) might not termitophile unlike the other Rhyparini species but free-living species. Therefore, it is assumed that the Korean R. helophoroides and R. azumai also have life cycles that are not closely related to the termites. Further study is needed to understand ecology of Rhyparus.