Scarabaeus (Pachysoma) aesculapius Olivier, 1789

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 : 312-316

Scarabaeus (Pachysoma) aesculapius Olivier, 1789

( figures 3 , 18 , 36, 57)

Scarabaeus aesculapius Olivier, 1789: 154 ; Olivier, 1790: 172; Hausmann 1807: 252; Mostert and Holm, 1982: 275. Lectotype designated here: no locality (1 3 BMNH).

Pachysoma aesculapius (Olivier) : MacLeay, 1821: 507; MacLeay, 1833: 55; Castelnau, 1840: 68; Reiche, 1841: 212; Reiche, 1842: 89; Péringuey, 1902: 77; Felsche, 1907: 273; Gillet, 1911a: 6; Ferreira, 1953a: 15; Ferreira, 1961: 22; Ferreira, 1966: 57; Ferreira, 1969: 20; Holm and Scholtz, 1979: 229.

Ateuchus barbatus Thunberg, 1818: 409 ; Gillet, 1911a: 6; Ferreira, 1953a: 15; Ferreira, 1961: 22. [Holotype]: no locality: [1 UPSS].

Pachysoma validum Boheman, 1857: 180 ; Péringuey, 1902: 78; Felsche, 1907: 273: Gillet: 1911a: 6; Ferreira, 1961: 22. [Lectotype]: Caffraria, Walberg: [1 NHRS].

Diagnosis. Clypeus bidentate, genal and clypeal edges unserrated and continuous ( figure 18 ); protibia not sexually dimorphic, with simple protibial spurs ( figure 36); well-developed sub-elytral ridge, slight elytral indument present in northern populations; metatarsal claws shorter than last tarsal segment; size range in populations increases from small in south to larger in north.

Distribution, habitat and conservation. Historically distributed from Cape Town (33 ° 56 ∞ S, 18 ° 28 ∞ E) to the mouth of the Olifants River (34 ° 05 ∞ S, 18 ° 33 ∞ E) ( figure 3 ). Locality records and fieldwork suggest that the Olifants River might be a barrier to the northward extension of S. (P.) aescualpius distribution. The southern populations (Somerset West; Cape Flats; Salt River; material only dated between 1882 and 1886) are possibly now extinct, as the most recent collection of S. (P.) aesculapius in the south is from the Modder River (33 ° 28 ∞ S, 18 ° 20 ∞ E) in 1987. Currently, the coastal section of the Modder River Farm (or Modderrivier) is run as a private nature reserve (Davis, 1999, personal communication).

Scarabaeus (Pachysoma) aesculapius appear to prefer firm sand on coastal hummocks, river banks and vegetated dunes. The short tarsal claws, hardly spatulate mesospurs and shorter tibial brushes than S. (P.) hippocrates support this field observation.

The West Coast National Park (WCNP) is the closest conservation area for S. (P.) aesculapius . A single record of S. (P.) aesculapius in the WCNP labelled ([Hopefield crossed out] Saldanha) and dated 1960, is in the SAMC. Although this locality is possible, it remains unconfirmed by all subsequent collecting. We suspect the use of a generalized label (same label format is used for five S. (P.) hippocrates ) referring to the Hopefield District rather than Saldanha Bay itself. Three days were spent by J. du G. Harrison (JduGH) during December 1996 in a variety of habitats in the WCNP looking specifically for S. (P.) aesculapius . No sign of this species was found, but adults and many fragments of S. (P.) hippocrates were collected. However, as S. (P.) aesculapius may be more cryptic in habit than S. (P.) hippocrates , one cannot exclude the possibility that S. (P.) aesculapius does occur in the WCNP, but currently it seems unlikely. As most of the historical distribution range of S. (P.) aesculapius is within modified or developing coastline, and since S. (P.) aesculapius might not be in the WCNP it must be regarded as the most threatened South African S. ( Pachysoma ) species.

Comments on locality data. All the specimens labelled Salt River have been ascribed to Salt River in Cape Town, and not to Salt River near Vredendal (as done by Holm and Scholtz, 1979) for the following reasons. These specimens match in all aspects of morphology (i.e. genitalia, pronotal microsculpture and body size) to the southern population (i.e. specimens labelled Cape Town). They were all collected during 1882 when Salt River in Cape Town was probably still a suitable locality for this species. No collectors have recorded S. (P.) aesculapius north of the Olifants River (which might be a barrier to the northern extension of the range of S. (P.) aesculapius ). Salt River (Vredendal) is north of this suspected boundary.

The single female labelled Bontebok National Park (BNP), Swellendam, matches S. (P.) aesculapius from Leipoldtville in morphology. Additionally, this record is undoubtedly incorrect as the Cape fold mountains ( Kruger, 1983) act as a barrier to the eastward movement of S. ( Pachysoma ) species. According to Irish (1996, personal communication) currently at the BMSA, the catalogue number (NMBH26926) for this specimen falls directly between long series of material from the BNP and other southern Cape localities from a single field trip. Thus retrospectively, there is no way of determining where the specimen actually came from. During February 1998 the BNP was visited by JduGH and no habitat remotely suitable for S. (P.) aesculapius was found.

A single male collected by Koch and labelled Strandfontein (near the Olifants River) (close to where S. (P.) aesculapius were collected by JduGH for this study), conforms to all aspects of morphology to S. (P.) aesculapius from the southern population. Koch (1952) lists the areas visited during the expedition on which this specimen was collected. They travelled from Cape Town to Strandfontein. We suspect that this specimen comes from the southern population, as it does not conform with S. (P.) aesculapius specimens collected near Strandfontein. The S. (P.) aesculapius from Zambia, Monze (16 ° 16 ∞ S, 27 ° 29 ∞ E) are clearly incorrectly labelled.

Morphological variation. The smallest specimens of S. (P.) aesculapius collected are all from the south (Cape Town, Cape Flats, Somerset West and Salt River). These populations share similar genitalia when viewed anteriorly, i.e. very narrow and straight parameres, and only 70% of the thorax is distinctly punctate. The type series of Scarabaeus aesculapius (length 21–24 mm, width 15–17 mm) is probably based on the southern population and distributed according to Boheman (1857) in all of Caffraria (i.e. ‘Caffraria tota’). Moving northwards from the Modder River to Strandfontein the parameres in anterior view are stouter with a distinct widening before the two paramere points meet, with 90% of the pronotal disc deeply and irregularly punctate. Populations in the north (from Leipoldtville inland) are characterized by having slight elytral indument and consequently very distinct elytral interstriae with single setose granules, interspersed by a smooth ridge (there are five ridges per elytron). This population probably represents individuals described as Pachysoma validum (length 27 mm, width 19 mm) occurring in the ‘Caffraria interiore’ ( Boheman, 1857). Holm and Scholtz (1979) examined the holotype of Ateuchus barbatus Thunberg and matched it to a female of S. (P.) aesculapius from Dwarskersbos. Curiously, however, the original description of A. barbatus recorded the clypeus as quadridentate ( Thunberg, 1818), whereas the clypeus of S. (P.) aesculapius is definitely bidentate.

Although specimens from the opposite ends of the S. (P.) aesculapius distribution share characteristics unique to them, the material examined suggests a cline in morphology rather than a clear division into two separate species or subspecies. For example, of the six S. (P.) aesculapius from Grootdrift the indument and elytral soil staining is marked in one male, but variable to absent in all other specimens.

Biology. All seven burrows of S. (P.) aesculapius excavated by JduGH contained only dry dung pellets. S. (P.) aesculapius occurs sympatrically with S. (P.) hippocrates and S. (P.) glentoni , which both prefer detritus rather than dry dung pellets. This suggests that these species coexist by having different dietary preferences.

Péringuey (1900) mentioned that S. (P.) hippocrates , S. (P.) aesculapius , S. (P.) striatus and S. (P.) denticollis are diurnal. Holm and Scholtz (1979) questioned Péringuey’s claim as they did not find any S. (P.) aesculapius active during the day other than by excavating their burrows. During December 1996 most S. (P.) aesculapius collected were from burrow excavation, but individuals were also seen to be active for a short period in the early morning (ca 7:00–9:00 a.m.), and late afternoon (ca 16:00–18:00 p.m.). The larvae are unknown.

Comments. Similar to S. (P.) hippocrates , but smaller, S. (P.) aesculapius has a dull cuticle, and well-preserved specimens from the north of their range have slight indument that highlights their elytral intervals.

Types. Holm and Scholtz (1979) could not trace the type of Scarabaeus aesculapius Olivier, 1789 . An old repined specimen of S. (P.) aesculapius labelled in the exact manner as MacLeay’s holotype of Pachysoma hippocrates , was found in the BMNH collection (see label data in type material below). MacLeay described the genus Pachysoma in 1821 and included two species in the genus, i.e. P. hippocrates and P. aesculapius . The possibility exists that MacLeay borrowed a specimen or specimens from Olivier, which MacLeay then labelled as his type (i.e. MacLeay’s type) or compared Olivier’s specimen with P. aesculapius material in the BMNH, before labelling it as his type (i.e. MacLeay’s type). As Olivier’s types are considered lost, this specimen either came from the Olivier series or was at least compared to Olivier’s type of S. aesculapius . Thus it is designated as the lectotype of Scarabaeus aesculapius Olivier, 1789 . This specimen agrees in microsculpture and genital structure, with S. (P.) aesculapius from near the Modder River (33 ° 28 ∞ S, 18 ° 20 ∞ E).

Péringuey (1902) could find no differences between P. aesculapius from Somerset West and one of Boheman’s ‘co-type’ of P. validum . Of the two paralectotypes of S. (P.) validum examined, both southern (1 3 BMNH) and northern (1 ♀ TMSA) populations of S. (P.) aesculapius may be represented (see morphological variation above), which would explain why Péringuey (1902) found no differences.

From the Boheman series of Pachysoma validum, Holm and Scholtz (1979) designated a male lectotype (1 3 NHRS) and three paralectotypes (2 uns. NHRS), (1 ♀ BMNH). An additional female paralectotype (see type material for label data) is however in the TMSA collection .

Type material examined (3 spec. [5], 1 ♀ 2 3, 2 3 diss.). SOUTH AFRICA: LECTOTYPE 3, Scarabaeus aesculapius Olivier , designated here: 1751 (typed) / M’Leay’s Type / (refer to type discussion above, white paper disk, with a red border with type printed, M’Leay’s written above type in the same hand writing as the holotype label of Pachysoma hippocrates ) / Pachysoma aesculapius [M’Leay’s type] Oliv. (written on white paper, same writing as before, brackets [] on original label), (1 3 BMNH); PARALECTOTYPES 2 of [3]: Pachysoma validum Boheman , designated by Holm and Scholtz (1979): Caffraria, J.Wahlb, Type, ♀ (four labels stuck on to one card [probably by Endrödy-Younga]) / Typus (typed in black on red card) / 378 77 (red paper, 378 printed, 77 written) / validum Bhm (written on white paper) / Paralectotypus, Pachysoma validum Boheman, Holm & Scholtz , (this paralectotype is not recorded by Holm and Scholtz (1979) as being in the TMSA collection), (1 ♀ TMSA); Caffraria. / J.Wahlb / C.Bon Spei / Fry Coll. 1905-100. / Paralectotype (typed on white circle with a light blue border) / P.validum paralectotype Holm & Scholtz 1978, (1 3 BMNH).

Additional material examined from South Africa (S173 specs [42], 61 ♀ 107 3, 28 3 diss., 5uns., 2eth., 7p.) .

Figures

FIGS 3–5. Distribution of Scarabaeus (Pachysoma) species in South Africa. Questioned locality records or range extensions are shown by an open circle. (3) S. (P.) aesculapius. (4) S. (P.) hippocrates. (5a) S. (P.) endroedyi and S. (P.) glentoni mapped at large scale to compare with S. (P.) hippocrates; (5b) S. (P.) endroedyi and S. (P.) glentoni mapped at small scale.

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.