Scarabaeus (Pachysoma) rotundigenus ( 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 : 340

Scarabaeus (Pachysoma) rotundigenus ( Felsche, 1907)

( figures 11 , 28 , 46, 67)

Pachysoma rotundigena Felsche, 1907: 273 ; Péringuey, 1908: 555; Gillet, 1911a: 6; Holm and Scholtz, 1979: 236. [Holotype]: Sinclair, S.W.A. [1uns. SMTD].

Neopachysoma rotundigena (Felsche) : Ferreira, 1953a: 43; Ferreira, 1961: 25; Ferreira, 1966: 60; Ferreira, 1969: 25; Zunino, 1977: 15.

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

Diagnosis. Clypeus quadridentate, outer clypeal teeth reduced in size; genae rounded and finely serrated ( figure 29 ); protibia dimorphic, protibial spurs bifid in both sexes ( figure 46); elytra smooth and shiny with no sub-elytral ridge; tarsal insertion sub-apical; metatarsal claws longer than last two tarsal segments; male genitalia as in figure 67a, b.

Distribution, habitat and conservation. This species occurs in the vegetated marginal inland dunes of the southern Namib dune area ( Holm and Scholtz, 1979) ( figure 11 ). The very long tarsal claws and enlarged tibial setal brushes suggest S. (P.) rotundigenus is adapted to soft dune sand. Conserved within the Namib-Naukluft Park.

Comments on locality data. The three specimens from the SE corner of the Namib-Naukluft Park extend the known distribution for S. (P.) rotundigenus northwards ( figure 11 ). Collected independently these specimens probably reflect real occurrence rather than incorrectly labelled specimens. The most northerly record of S. (P.) fitzsimonsi is from near this locality. As S. (P.) fitzsimonsi and S. (P.) rotundigenus occur close to one another in the south, these overlapping range extensions corroborate these new records.

Morphological variation. The three (2 ♀ 1 3) most northerly specimens (SE of Namib-Naukluft Park) match in all morphological attributes, including male genitalia to that of S. (P.) rotundigenus .

Biology. Biology unknown. However, they occur in vegetated dunes where detritus readily accumulates around the base of plants. This habitat and their long metatarsal claws suggest a detritus feeding diet. The larvae are unknown.

Comments. Easily confused with S. (P.) fitzsimonsi , but differentiated by the absence of a sub-elytral ridge, sub-apical insertion of the tarsi on the tibia and long metatarsal claws.

Types. A body length of 26 mm is given by Felsche (1907) in the description of Pachysoma rotundigena , suggesting that he only examined one specimen. However, two collections (Collection Felsche and Collection Bennigsen, Berlin) are listed as having material, suggesting more than one specimen was examined ( Felsche, 1907).

Type material {> uns. 2 spec.}. NAMIBIA: [HOLOTYPE], Sinclair, (25.44S 16.22E), D.S.W. Afrika, [1uns. SMTD] .

Additional material examined from Namibia (S50 specs [33], 19 ♀ 31 3, 4 3 diss.) .

Figures

FIGS 10–13. Distribution of Scarabaeus (Pachysoma) species in Namibia. Questioned locality records or range extensions are shown by an open circle. (10) S. (P.) fitzsimonsi. (11) S. (P.) rotundigenus. (12) S. (P.) rodriguesi. (13) S. (P.) denticollis.

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.