Metabiantes leighi ( Pocock, 1902 )

Schönhofer, Axel L., 2008, On harvestmen from the Soutpansberg, South Africa, with description of a new species of Monomontia (Arachnida: Opiliones), African Invertebrates 49 (2), pp. 109-109 : 111-113

Metabiantes leighi ( Pocock, 1902)

Figs 2 , 3A, 3B

Hinzuanius leighi: Pocock 1902: 412 .

Biantes leighi (Pocock) : Roewer 1912: 177.

Spinibiantes leighi (Pocock) : Roewer 1915: 27; 1949: 249, fig. 9.

Metabiantes leighi (Pocock) : Lawrence 1931: 356; 1933: 218, fig. 3; 1938 b: 340; Stare,ga 1992: 327.

Comments on morphology: Sexual dimorphism is poorly developed. Chelicerae of males are more massive and therefore the carapace in the eye region is wider. The scutum is more triangular in males ( Fig. 3B ), whereas the opisthosoma in females is more rounded. Differences like shape of the body and intensity of coloration are strongly influenced by the age of the individual after final moult. Juveniles have larger spines on the dorsal scute than adults. This might be of interest because Kauri (1961: 62) pointed to a juvenile Metabiantes being distinct due to its strong spination, although he had no assignable juveniles of spined species for comparison.

Material examined: SOUTH AFRICA: Limpopo: 18ơ 22^6 juv. Lajuma , evergreen montane forest, alt. 1300–1400 m, 1–4.iv.2001, P. Schwendinger ( MHNG); 4ơ 1^23 ° 02'30.0''S: 29 ° 26'48.5''E, alt. 1325 m, 24.x.2002, A.L. Schönhofer ( CJM, 4093) .

Ecology: M. leighi inhabits the medium layer of leaf litter in subtropical evergreen forest. The species seems to require lower humidity than, for example, Monomontia aquilonaris . It was also absent from wet forest soils near streams and springs.

Comments:As Lawrence (1963) recorded a considerable number of cryptic and difficultto-access species of the genera Monomontia and Purcellia near Makhado, we can assume that Metabiantes leighi was not present there. At Lajuma, M. leighi was quite common to abundant, and is a new record for Limpopo Province.

Most species of the genus Metabiantes have a limited distribution, whereas the scattered records of M. leighi encompass a range of more than 1000 km along the eastern coast of South Africa ( Lawrence 1931, 1933).A closer investigation of different geographic populations of M. leighi enabled Kauri (1961) to separate Metabiantes cataracticus Kauri, 1961 and M. hanstroemi Kauri, 1961 from the M. leighi area. All three species are close relatives by the shape of the glans penis (Lawrence 1933; Kauri 1961). Martens (1978 a) showed allopatric speciation by geographic isolation in Biantidae from the Himalayas. This isolation forced minor morphological changes, whereas sympatric species differ strongly with respect to body size and shape of chelicerae and palps. Consequently, the syntopic M. cataracticus and M. hanstroemi should differ in the proportion of palps, body size and chelicerae, but these characters were not thoroughly investigated by Kauri (1961). Comparing body size (2.7 mm; 2.4 mm), length of the enlarged part of chelicerae (0.35 mm; 0.28 mm), spination and coloration of the two species, there is agreement with the evolutionary concept proposed by Martens (1978 a) and parallels within the African Biantidae seem to hold true. A revision of the different populations of M. leighi might reveal cryptic species. For further investigation we document characters of M. leighi from Lajuma ( Fig. 2 ), as recommended by Martens (1978 a).

Figures

Fig. 2. Metabiantes leighi ơ, Lajuma: (A) chelicerae, (B) palpus, (C) penis, (D–G) glans penis, (F, G) expanded view. (A, B, E, F) lateral aspect, (C, D, G) dorsal aspect. Scale bars: top left 0.2 mm for A, B; bottom left 0.2 mm for C; bottom right 0.1 mm for D–G.

Fig. 3. General habitus of harvestmen from Lajuma: (A, B) Metabiantes leighi ^and ơ; (C, D) Graemontia bicornigera ^; (A, D) lateral aspect; (B, C) dorsal aspect. Scale bars = 1.0 mm.