Scarabaeus (Pachysoma) schinzi ( Fairmaire, 1888 )

Harrison, J. Du G., Scholtz, C. H. & Chown, S. L., 2003, A revision of the endemic south-western African dung beetle subgenus Scarabaeus (Pachysoma) MacLeay, including notes on other flightless Scarabaeini (Scarabaeidae: Scarabaeinae), Journal of Natural History 37 (3), pp. 305-355 : 336-337

Scarabaeus (Pachysoma) schinzi ( Fairmaire, 1888)

( figures 9 , 25 , 43, 64)

Pachysoma schinzi Fairmaire, 1888: 178 ; Péringuey, 1902: 80; Felsche, 1907: 273; Gillet, 1911a: 6; Ferreira, 1953a: 26; Ferreira, 1961: 24; Ferreira, 1966: 59; Ferreira, 1969: 21; Holm and Scholtz, 1979: 235. [Holotype]: no locality [1 3 MNHN].

Scarabaeus schinzi (Fairmaire) : Mostert and Holm, 1982: 275.

Diagnosis. Sexual dimorphism of head marked ( figure 25a, b ), males with bifid clypeal horns ( figure 25b ); protibia serrated between and proximal to protibial teeth ( figure 43a, b), distance between second and third protibial teeth (especially in male) greater than between other protibial teeth; elytra smooth, with no sub-elytral ridge; metatarsal claws shorter than last tarsal segment.

Distribution, habitat and conservation. Confined to the gravel plains around Aus (26 ° 41 ∞ S, 16 ° 16 ∞ E) on the Huib-Hoch Plateau ( figure 9 ). S. (P.) schinzi has a very restricted distribution and its conservation status is unknown. S. (P.) schinzi is not contained within any conservation area.

Comments on locality data. The Tinkasfläche specimens collected by Gaerdes occur well out of the confirmed distribution range of S. (P.) schinzi . Irish (1995) examined Gaerdes original diaries and verified that Gaerdes confused the name’s Tinkasfläche (22 ° 53 ∞ S, 15 ° 23 ∞ E) with Tiras Plains (26 ° 08 ∞ S, 16 ° 38 ∞ E) before about 1967. The Tiras Plains (to the north of Aus) are well within the expected distribution of S. (P.) schinzi ( figure 9 ).

Morphological variation. Size of the clypeal horns varies slightly, but the shape is consistent within the species.

Biology. Biology unknown. Louw (label data) collected S. (P.) schinzi under plants, and according to Owen (1997, personal communication) S. (P.) schinzi feeds on vegetation (presumably fallen flower petals and detritus).

During September of 1950 Koch and van Son collected 88 females and 70 males of S. (P.) schinzi from Aus. This represents the longest series ever collected for any S. ( Pachysoma ) species and forms 84% of available material for S. (P.) schinzi . Subsequently only 10 females and 21 males have been collected. Possible reasons for this apparent lack of material since 1950 might include the following: (1) an artifact of collectors’ activities and objectives; (2) the unpredictable activity period of S. (P.) schinzi a consequence of unpredictable rainfall near Aus; (3) habitat modification around Aus.

The ratio between females and males (1.25 ♀: 1 3) suggests the Aus population sampled in 1950 was at an early stage in their breeding cycle. All 158 specimens collected are mature individuals (no tenerals are present) and the protibial and clypeal wear on some specimens suggests that this sample represented only mature adults most probably of at least 1–2 years (seasons) old. The small numbers of subsequently collected S. (P.) schinzi could be the result of the large sample taken in 1950. Especially as the restricted distribution range ( figure 2d) and low vagility of S. (P.) schinzi reduces the potential for recolonization. If this is the case, future coleopterists should refrain from over-collecting any local population of S. ( Pachysoma ). The larvae are unknown.

Comments. Rare in collections, probably due to their limited distribution and an activity period linked to unpredictable rainfall (but also see Biology). S. (P.) schinzi straddles the boundaries between the Desert, Nama-Karoo and Succulent Karoo Biomes ( Rutherford and Westfall, 1994) on the Huib-Hoch Plateau.

Types. Fairmaire (1888) described only the male of Pachysoma schinzi , a single body length (29 mm) suggests one specimen was examined from ‘Namaqua-Land’. Felsche (1907) noted the differences between the sexes and described the female of P. schinzi .

Type material. NAMIBIA: [HOLOTYPE 3], Pachysoma schinzi Fairmaire : Namaqua-Land , [1 3 MNHN]. Holm and Scholtz (1979) suspect the holotype comes from the vicinity of Aus .

Additional material examined from Namibia (S189 specs [192], 98 ♀ 91 3, 5 3 diss.) .

Figures

FIGS 6–9. Distribution of Scarabaeus (Pachysoma) species in South Africa and Namibia. Questioned locality records or range extensions are shown by an open circle. (6) S. (P.) striatus. (7) S. (P.) gariepinus. (8) S. (P.) bennigseni. (9) S. (P.) schinzi and S. (P.) valeflorae.

FIGS 18–35. (18–30) Head of Scarabaeus (Pachysoma) species in dorsal view: (18) S. (P.) aesculapius. (19) S. (P.) hippocrates. (20) S. (P.) glentoni. (21) S. (P.) endroedyi. (22) S. (P.) striatus. (23) S. (P.) gapiepinus. (24) S. (P.) bennigseni. (25) S. (P.) schinzi: (a) female, (b) male. (26) S. (P.) valeflorae: (a) female, (b) male. (27) S. (P.) fitzsimonsi. (28) S. (P.) rotundigenus. (29) S. (P.) rodriguesi. (30) S. (P.) denticollis. (31, 32) Head of flightless Scarabaeus (Scarabaeolus) species in dorsal view. (31) S. (Scarabaeolus) scholtzi. (32) S. (Scarabaeolus) silenus. (33–35) Head of flightless Scarabaeus (Scarabaeus) species in dorsal view. (33) S. (Scarabaeus) ritchiei. (34) S. (Scarabaeus) sevoistra. (35) S. (Scarabaeus) cancer.