Scarabaeus (Pachysoma) bennigseni ( Felsche, 1907 )

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 : 333-336

Scarabaeus (Pachysoma) bennigseni ( Felsche, 1907)

( figures 8 , 24 , 42, 63)

Pachysoma bennigseni Felsche, 1907: 274 ; Péringuey, 1908: 556; Gillet, 1911a: 6; Ferreira, 1953a: 35; Ferreira, 1961: 22; Ferreira, 1966: 59; Ferreira, 1969: 20; Holm and Scholtz, 1979: 235. [Holotype]: Orange River [1uns. SMTD].

Pachysoma granulatum Ferreira, 1953b: 2 ; Ferreira, 1961: 23; Ferreira, 1966: 59; Ferreira, 1969: 20. Holotype: Namtib (1 3 TMSA).

Scarabaeus bennigseni (Felsche) : Mostert and Holm, 1982: 275.

Diagnosis. Clypeus quadridentate, outer clypeal teeth reduced in size and deflexed outwards; genae serrated and discontinuous from clypeus ( figure 24 ); protibia hardly sexually dimorphic, protibial spurs sinusoidal in males and straight in females ( figure 42); small (length 23 mm; width 14.24 mm), black; elytra granular to smooth, markedly flat and deeply striate; metatarsal claws equal in length to last tarsal segment.

Distribution, habitat and conservation. Coastal species occurring from just south of the Orange River (i.e. Holgat River mouth) to Spencer Bay north of Lüderitz ( figure 8 ). The northern population is conserved within the Namib-Naukluft Park, but the central and southern populations occur within Diamond Area 1 and Alexkor mining property, respectively. Preferred habitats include coastal sand dunes and sand flats on unstable to compacted sand.

Comments on locality data. The Dassiefontein/Sneeukop locality record on the escarpment near Kamieskroon is very unlikely ( figure 8 ). This locality falls well out of the confirmed range of S. (P.) bennigseni and is a record that is both further inland and at a higher elevation than expected for this coastal sand plain to sand dune species. The genitalia of this single male are typical of S. (P.) bennigseni .

Morphological variation. S. (P.) bennigseni occurs on both sides of the Orange River, which is a potential barrier between the two populations. Examination of external features and male genitalia reveals no evidence that these allopatric populations represent separate species. South of the Orange River S. (P.) bennigseni has smoother elytra and specimens are larger, while north of the river they are smaller but with well-defined elytral interstriae and distinct granular elytral sculpture. Within populations the elytral sculpture varies only slightly, unlike S. (P.) gariepinus and S. (P.) striatus . This minor morphological difference is clinal and consistent with that seen throughout S. ( Pachysoma ) species.

Biology. According to Holm and Scholtz (1979) foraging and tunnelling are very similar to S. (P.) gariepinus . A single nest was excavated by JduGH at Jam Pan that contained a mixture of detritus and dung pellets. The larvae are unknown.

Comments. S. (P.) bennigseni superficially resembles S. (P.) denticollis (black form), but lacks dimorphic protibia.

Types. Although Felsche (1907) records only a single length (20 mm) in his description of Pachysoma bennigseni he lists two collections (Collection Felsche and Collection Bennigsen) in which material is deposited, which suggests more than a single type specimen. Holm and Scholtz (1979) examined the holotype from Oranjefluss (Orange River) in the SMTD collection.

Ferreira (1953b) described Pachysoma granulatum and subsequently ( Ferreira, 1966) synonymized it with Pachysoma bennigseni . Holm and Scholtz (1979) only mention the holotype, allotype and four paratypes for P. granulatum . The type series of P. granulatum comprised 29 specimens ( Ferreira, 1953b). Twenty-six types are in the TMSA collection, while the remaining three are reputed to be in the BMNH and CPMM collections. There are two sets of specimens from the type locality (i.e. Daberas dunes) which could create confusion in the future. The type series (9 ♀ 17 3) is labelled with handwritten locality labels while the second series (9 ♀ 11 3) has printed labels.

Type material examined (S26 specs [7], 9 ♀ 17 3, 1 3 diss.). NAMIBIA: HOLOTYPE 3, Pachysoma granulatum Ferreira : S. Great Namaq., Daberas dunes, (28.13S 16.45E), v.1953, C. Koch (written on faded white card) / (male genitalia point mounted) / Holotype, Pachysoma granulatum 3, M.C.Ferreira, 1953 (written on white card) / Holotypus, Pachysoma granulatum, M.C.Ferreira sp.n. (Endrödy- Younga label), (1 3 TMSA) ; Allotype ♀, idem, but / Alotype (sic) Pachysoma granulatum ♀, M.C.Ferreira, 1953 (written on white card) / Allotypus, Pachysoma granulatum, M.C.Ferreira sp. n. ( Endrödy-Younga label), (1 ♀ TMSA) . PARATYPES: idem, but Paratipo (red ink) Pachysoma granulatum, M.C.Ferreira (written on white card, all the paratypes are labelled by both Ferreira and Endrödy-Younga), (8 ♀ 16 3 TMSA); [2uns. BMNH]; {1uns. CPMM }.

Additional material examined from South Africa and Namibia (S137 specs [24], 49 ♀ 87 3, 4 3 diss., 1uns.) .

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.