Scarabaeus (Scarabaeolus) scholtzi Mostert and Holm, 1982

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 : 345-346

Scarabaeus (Scarabaeolus) scholtzi Mostert and Holm, 1982

( figures 14 , 31 , 49, 70)

Scarabaeus (Scarabaeolus) scholtzi Mostert and Holm, 1982: 276 .

Mnematium scholtzi ( Mostert and Holm, 1982) : Carpaneto and Piattella, 1988: 269.

Diagnosis. Clypeus quadridentate, outer clypeal teeth half size of medial teeth, medial teeth separated by broad ‘U’ shaped gap; genal and clypeal edges unserrated, and separated by an incision at genal–clypeal suture ( figure 31 ); protibia quadridentate, serrations between and proximal to teeth ( figure 49); elytra fused, humeral callus absent, no sub-elytral rim, small elytral rim, elytral striae very faint; second mesotibial spur, vestigeal which places this species in subgenus Scarabaeolus ( Mostert and Scholtz, 1986) ; metatarsal claws, shorter than last tarsal segment; aedeagus symmetrical ( figure 70a, b).

Distribution and habitat. Endemic to the coastal plains of Somalia ( figure14 ), occurring in what is also known as the Somali-Chalbi Desert ( Costa, 1995). Koch (1961) includes a photograph by C. F. Hemming (who collected the type series of S. (Scarabaeolus) scholtzi ) of Somalian dunes, east of Berbera. This picture possibly depicts likely habitat for S. (Scarabaeolus) scholtzi .

Morphology. The head of S. (Scarabaeolus) scholtzi resembles that of Sceliages species in shape. The mesocoxae of S. (Scarabaeolus) scholtzi are completely contiguous as with all Pachysoma species, but unlike Pachysoma the mesosternal ridge is still present as a distinct hump.

Biology. The mouthparts of S. (Scarabaeolus) scholtzi do not appear to be adapted for feeding on dry dung or detritus as in S. ( Pachysoma ) species. The epipharynx of S. (Scarabaeolus) scholtzi and Sceliages brittoni are strikingly similar in morphology. Towards the end of the wet season on the Namaqualand coast, dead millipedes became abundant in certain sandy areas. As Sceliages brittoni feeds mainly on dead millipedes, perhaps S. (Scarabaeolus) scholtzi has a similar diet which could account for the convergence in epipharyngeal morphology. It seems possible that dead millipedes could be an abundant, localized, but short-lived food resource for a flightless beetle?

Comments. Dr Charles Koch visited Somalia in 1958 and collected an abdomen with elytra of a flightless Scarabaeini . Ferreira (1966) examined this abdomen and suggested without reasons that it came from a Pachysoma species. Holm and Scholtz (1979) were unable to find this elytron in the TMSA collection and queried how Ferreira (1966) determined it to be a Pachysoma rather than a Mnematium species. Mostert and Holm (1982) were also unable to trace this elytron, but mentioned that it probably belonged to S. (Scarabaeolus) scholtzi . The abdomen was discovered in the BMSA collection (which curates some of Ferreira’s collection). It consists now of two complete elytra and all the abdominal sternites. Although labelled from Somalia, the specimen was puzzling because the head and thorax were that of S. (Scarabaeus) ritchiei . However, due to the distinct mesosternal ridge, and a protuberance on the outer edge of the last abdominal sternite, characters which are absent in S. (Scarabaeus) ritchiei , the abdomen was determined to be that of S. (Scarabaeolus) scholtzi . Further examination revealed that the S. (Scarabaeus) ritchiei pronotum and head were glued to the S. (Scarabaeolus) scholtzi abdomen, suggesting a previous mismatch. The parts of the two species have been separated and the S. (Scarabaeolus) scholtzi abdomen deposited in the TMSA collection.

Types. Mostert and Holm (1982) record 13 type specimens, but only 11 were traced. The BMNH and UPSA collections are listed by Mostert and Holm (1982) as having two paratypes each, while only one paratype was found in each of these collections.

Type material examined (S11uns. specs, 1 3 diss.). SOMALIA: HOLOTYPE 3; NE. Afr. Somali Rep , 52 km NE El Den, (04.53N 47.38E), coastal plain / 28.10.1971, Hemming T 238 / Holotype, Scarabaeus scholtzi Mostert & Holm 1982 , (1 3 TMSA) . PARATYPES: idem, but Paratype, Scarabaeus scholtzi Mostert & Holm 1982 , (1uns. BMNH), (6uns. TMSA), (1uns. UPSA); Somali Rep. , 90 km N. Obbia on Geriban road, (06.53N 48.38E) / T 240 2.xi.1971, C.F. Hemming / Paratype, Scarabaeus scholtzi Mostert & Holm 1982 , (2uns. TMSA) .

Additional material examined from Somalia (1uns. abdomen).

Figures

FIGS 14–17. Distribution of flightless Scarabaeus (Scarabaeolus) and Scarabaeus (Scarabaeus) species in Africa, the Middle East and Madagascar. (14) S. (Scarabaeolus) scholtzi in Somalia. (15) S. (Scarabaeolus) silenus in Sinai, Syria, and Iraq. (16) S. (Scarabaeus) ritchiei in Libya. (17) S. (Scarabaeus) sevoistra in Madagascar. See figure 2 for distribution of S. (Scarabaeus) cancer in Angola.

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.