Scarabaeus (Pachysoma) gariepinus (Ferreira, 1953)

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 : 330-333

Scarabaeus (Pachysoma) gariepinus (Ferreira, 1953)

( figures 7 , 23 , 41, 62)

Pachysoma gariepinus Ferreira, 1953a: 23 ; Ferreira, 1961: 24; Ferreira, 1969: 21; Holm and Scholtz, 1979: 231. Holotype: Namaqualand, Holgat. (1 3 TMSA).

Scarabaeus gariepinus (Ferreira) : Mostert and Holm, 1982: 275.

Diagnosis. Clypeus bidentate, but vestigeal outer clypeal teeth sometimes present; genal and clypeal edges serrate ( figure 23 ); protibia not dimorphic with simple protibial spurs ( figure 41); band of indument on elytral and pronotal outer edges; metatarsal claws shorter than last tarsal segment; genitalia illustrated in figure 62a, b.

Distribution, habitat and conservation. S. (P.) gariepinus is distributed on either side of the Orange River ( figure 7 ). The southern most extent of S. (P.) gariepinus distribution in South Africa coincides with the Buffels River (29 ° 33 ∞ S, 17 ° 24 ∞ E), while S. (P.) gariepinus occurs to Agub Mountain (26 ° 59 ∞ S, 15 ° 58 ∞ E) in Namibia. The preferred habitat of S. (P.) gariepinus is firm consolidated sand of dunes, river banks and inland flats. No specimens were collected (by JduGH) from dunes south of the Orange River, but only from inland sandy flats, river banks and the bases of sandblown outcrops. North of the Orange River S. (P.) gariepinus appears to have a closer association with dunes. Northern populations of S. (P.) gariepinus occur within the Namib-Naukluft Park.

Comments on locality data. Specimens from Brandvlei, Kakamas, and the Groen River Mouth all occur outside the established distribution range of S. (P.) gariepinus , and are probably incorrectly labelled specimens. However, the Kakamas record could be evidence that S. (P.) gariepinus can move inland along the Orange River.

Morphological variation. The following attributes of S. (P.) gariepinus vary within and between localities: size; elytral sculpture; indument; and size of the mesipisternal protuberance. The Namaqualand populations (south of Orange River) are characterized by smaller body size and red indument, while the Namibian populations are generally larger in body size with their indument stained white to grey. Specimens from Rosh Pinah (27 ° 53 ∞ S, 16 ° 50 ∞ E) have very white indument and smooth elytra lacking distinct interstriae and granules. However, their genitalia conform to the typical S. (P.) gariepinus form.

A distinct mesepisternal protuberance (MEP), previously not mentioned by other authors, was noticed in specimens of S. (P.) gariepinus from Namibia. To determine if the MEP differentiated S. (P.) gariepinus into one species on either side of the Orange River it was examined in all available material. The MEP varies within and between populations and sexes. It appears larger in males and especially large males while smaller in females. It varies from virtually no expression in the Namaqualand populations to being well defined in the Namibian populations. For example, it is slightly expressed in some males but no females in populations close to the Buffels River (e.g. Wolfberg). It becomes markedly more defined in S. (P.) gariepinus populations near Port Nolloth, while Hohenfels ( Namibia) populations have it well expressed. The MEP clearly suggests a cline from south to north and supports the variation seen within S. (P.) gariepinus as attributable to one species. Further support for the continuity of the Namaqualand and Namibian populations is provided by male genitalia and elytral sculpture.

Biology. Holm and Scholtz (1979) observed S. (P.) gariepinus collecting Oryx gazella pellets that they dragged forward one at a time to their burrows. Mostert and Holm (1982) reported that ‘When fresh horse droppings were presented to Scarabaeus gariepinus specimens in their natural surroundings, they would cut out a ball about 20 mm in diameter and roll it backwards in the same way as do the fully winged Scarabaeus species’. This exact experiment was repeated in Namaqualand but S. (P.) gariepinus only showed interest in the horse dung when it was dry. Only then would they break off a small piece of dry dung using their protibia and clypeus and drag it with their hind legs to their preconstructed burrow. Of the 17 nests excavated by JduGH; nine contained only dry dung pellets; three contained only detritus; while five contained both pellets and detritus. This suggests that S. (P.) gariepinus is predominately a dry pellet feeder.

S. (P.) gariepinus were successfully bred in captivity and three larvae were obtained. Larval observations and comments concur with S. (P.) striatus above.

Comments. S. (P.) gariepinus superficially resemble S. (P.) striatus females, but the two species are easily separated as S. (P.) striatus has a hook on the posterior lateral pronotal edge that is absent in S. (P.) gariepinus .

Types. Ferreira (1953a), designated a holotype (3), allotype (♀) and 55 unsexed paratypes in her description of Pachysoma gariepinum . These types were deposited as follows: holotype, allotype and 51 paratypes in the TMSA collection; three paratypes in the UPSA collection; and one paratype in the CPMM collection. The three UPSA paratypes have subsequently been deposited in the TMSA, while no material from the CPMM collection in Mozambique was borrowed by Holm and Scholtz (1979) or in this revision. Holm and Scholtz (1979) noted that the holotype and most of the paratypes could be traced in the TMSA collection, although not labelled as such. Fortunately, Ferreira (1953a) listed the respective numbers of specimens from each locality, except the Holgat locality. However, via subtraction 12 paratypes were from Holgat. The allotype was not labelled, and since there are 10 females from Holgat it becomes untraceable.

To add to the confusion of the type series, two separate series from Holgat dated 23 November (19)48 and 2 September 1950 exist. Only the 1948 date is recorded in Ferreira’s (1953a) description, although some of the specimens from 1950 also bear Ferreira’s paratype labels. As these specimens (i.e. Holgat 1950) were not published as types, they are invalid. We have taken the opportunity of having all available type material together to label traced paratypes. These labels are printed on yellow card copying Ferreira’s format and spelling verbatim. None of Ferreira’s (1953a) original labels were removed. Thus, of the original 55 paratypes, 46 are traced and labelled as such.

Type material examined (S 47 spec. [50], 20 ♀ 28 3, 14 3 diss.). SOUTH AFRICA: HOLOTYPE 3, Pachysoma gariepinus Ferreira : Holgat, (28.56S 16.47E), NW C.P., 23.xi.(19)48, Koch & V. Son, / Tipo Pachysoma gariepinus 1951 M.C.Ferreira (written in red ink on white rectangular card with a black frame), (1 3 TMSA), (Allotype not marked, therefore untraceable). PARATYPES: idem, (10 ♀ 3 3 TMSA); Anenous, (29.14S 17.40E), 15.xi.1933, G. v. Son, (9 3 TMSA), idem, but / VII, 950 /, (1 3 TMSA); Brandkaross, (written in pencil, possibly from Gaerdes collection), (28.28S 16.40E), (1 ♀ 1 3 TMSA), idem, but / NMBH3685 / 203 /, (1 3 BMSA); 12m S of Grootderm, (ca. 28.37.05S 16.37.05E), (Groot Derm 10), 11.ix.1950, G.van Son, C.Koch, (1 ♀ TMSA); Oograbies, (29.13S 17.08E), L. Namaquald., 30.viii.(19)50, C.Koch, G. van Son, (3 ♀ 5 3 TMSA); Oograbies, (29.13S 17.08E), (written in black ink), (1 ♀ 1 3 TMSA); Ograbies, (29.13S 17.08E), (written in black ink), (1 3 TMSA); Pt Nolloth, (29.17S 16.51E), Warden, S. / Pachysoma gariepinus Fer. 1951 , M.C.Ferreira (written on white paper in black ink, black border around rectangle), (1 ♀ TMSA); Pt. Nolloth. C.C., (29.17S 16.51E), R.M.Lightfoot, Pt. Nolloth. C.C. / Pachysoma marginatum / Pachysoma gariepinus Fer. 1951 , M.C.Ferreira (written on white paper in black ink, black border around rectangle), (1 ♀ TMSA); Pt Nolloth, (29.17S 16.51E), 1885, (1 ♀ SAMC). NAMIBIA: Namib, sens. Eberlanz, (1 ♀ 2 3 TMSA); idem, but Eberelanz (1 3 TMSA); Oranjemund, SWA, (28.33S 16.37E), 21. 6 or 8.(19)42, (1 3 TMSA).

Additional material examined from South Africa and Namibia (S453 specs [16], 188 ♀ 235 3, 11 3 diss., 13uns., 17eth., 20p.) .

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.