The genus Gyronotus currently includes six species, subdivided into three species groups on the basis of their biogeographic distribution, body shape and structure of male genitalia (Davis et al. 2008). They are all wingless, with fused elytra, and are regarded among the most endangered of the African Scarabaeinae because of their sensitivity to disturbance. All species described so far, apart from Gyronotus glabrosus which is an upland grassland dweller (A. Davis pers. comm.), are linked to coastal and low-lying forest habitats, which have undergone massive transformation during the past 50–100 years, through clearance, degradation and fragmentation (Davis et al. 1999, Mucina and Rutherford 2006). Gyronotus fimetarius Kolbe, 1894, and Gyronotus carinatus Felsche, 1911, have disappeared from large parts of their original distribution range, namely the East Usambara Mountains of Tanzania and south of Maphelane in KwaZulu-Natal, respectively (Davis et al. 2008).

On the basis of the wide gaps existing between the distribution ranges of the species currently described, Davis et al. (2008) correctly predicted that new records and species would be discovered in the future. Here, we report on two new species that have only recently being recognised and collected in sufficient number to warrant their description. In the case of Gyronotus perissinottoi sp. n., ecological observations have also been possible, through repeated survey exercises. This species occurs in a small but biodiversity unique area in southern KwaZulu-Natal. The first female specimen was collected already in 2004 and a second one in 2007, but it was only in January 2013 that a full series including males was finally secured, through intense search and trapping efforts. The second species, Gyronotus schuelei sp. n., originates from western Swaziland and is currently known only from two specimens, one male and one female, collected in different places and on separate occasions.

As part of the collecting efforts, ground traps baited with fresh baboon dung were deployed in the Umthamvuna Reserve during December 2012 and January 2013. Traps consisted of 600 ml plastic jars of 80 mm mouth diameter and 120 mm height buried in the soil with the top levelled with the ground. They were checked at regular intervals of 2–5 days and after each visit traps were first emptied and then re-supplied with fresh dung.

The description of morphological characters follows the terminology used by Davis et al. (1999). Specimen length was measured from the anterior margin of the clypeus to the apex of the pygidium. Specimen width represents the maximum width of the elytra. Photos of the holotypes and allotypes were taken using a Canon EOS 400D camera fitted with a Canon MP-E 65 mm objective. Photos were processed with photo stacking technique, using Combine ZP (freeware free software by Alan Hadley, http://www.hadleyweb.pwp.blueyonder.co.uk). The first author compiled the taxonomic part of this study, including the descriptions of the new species. The second author collected all the specimens, with one exception, and contributed all habitat description and ecological observations.

Collections are abbreviated as follows: TMSA, Ditsong National Museum of Natural History (formerly Transvaal Museum), Pretoria, South Africa; ISAM, Iziko South African Museum, Cape Town, South Africa; PMOC, Collection Philippe Moretto, Toulon, France; PCRP, Private Collection R. Perissinotto & L. Clennell, Port Elizabeth, South Africa. Geographical abbreviations are as follows: KZN, KwaZulu-Natal Province, South Africa; SWA, Swaziland.

The genus Gyronotus is part of the tribe Canthonini, which has long been recognised as a Gondwanaland relict (Halffter 1974; Davis et al. 1999). Members of the genus are also wingless and particularly vulnerable to environmental disturbance (Davis et al. 2008). Thus, they are undoubtedly of substantial biodiversity and conservation value, with status ranging from vulnerable to critically endangered (Davis et al. 1999). Much of their recent demise has been attributed to the rapid disappearance of their predominantly forest habitats (Low and Rebelo 1996; Mucina and Rutherford 2006). Indeed, five of the six species described prior to this study are regarded as strictly forest specialists, occurring in coastal and low-lying montane forests on the seaboard of southern and east Africa (Davis et al. 2008).

The two new species described here, Gyronotus perissinottoi sp. n. and Gyronotus schuelei sp. n., together with Gyronotus glabrosus, are actually grassland or savanna inhabitants. The first is found exclusively in open coastal sourveld with scattered shrubs and small trees, on the plateau and escarpment just above the scarp forest that characterise the Umthamvuna River Gorge, at altitudes of 300–400 m (Figures 3–4). According to the classification scheme of Mucina and Rutherford (2006), this is part of vegetation unit CB4 known as Pondoland-Ugu sandstone coastal sourveld. This is a grassland type that, while exhibiting a large plant diversity and several local endemics, is also among the six most vulnerable vegetation units in South Africa (Mucina and Rutherford 2006). The scarp forest just below, within the gorge, constitutes the typical habitat of Gyronotus pumilus.

The Mlilwane and Malolotja reserves of western Swaziland, where Gyronotus shuelei sp. n. has been recorded so far, are higher altitude (700–1500 m) hilly areas (Figure 5) that exhibit vegetation units of the KaNgwane montane grassland and Swaziland sour bushveld types, coded respectively Gm 16 and SVI 14 in Mucina and Rutherford (2006). Here, the short and closed grassland layer includes many forbs and scattered shrubs on and around the rocky outcrops. The savanna component consists of a generally open, medium-tall tree layer over a closed, well-developed grass layer. These vegetation units are only regarded as “vulnerable” at present, as a reasonable proportion of the total area is under statutory conservation but much of the remaining part has already been converted to plantations of alien trees or cultivation (Mucina and Rutherford 2006).

Concerning food exploitation, at Umthamvuna Gyronotus perissinottoi sp. n. appears to rely mainly on Chacma baboon (Papio hamadryas) dung, while Gyronotus pumilus inside the forest is regularly observed in or on bushpig (Potamochoerus larvatus) dung (RP pers. observ.). The vast majority of Gyronotus perissinottoi sp. n. specimens were trapped among rock boulders and outcrops scattered within the grassland, suggesting the possibility that adults may actually prefer to hide dung pellets with eggs under rocks or in crevices, rather than bury them deep into the soil.

No information was unfortunately collected regarding food preferences in Gyronotus schuelei sp. n., but the specimen collected at Mlilwane was found during daytime on unidentified herbivore dung. Davis et al. (2008) suggested that species of the genus Gyronotus may be day-active. This is confirmed by observations made during the present study, as both species described here as well as Gyronotus pumilus were collected while active on the ground during daytime.