Amynthas minimus ( Horst, 1893 )

Nxele, Thembeka C., 2012, The megadrile fauna (Annelida: Oligochaeta) of Queen Elizabeth Park, South Africa: species composition and distribution within different vegetation types, African Invertebrates 53 (2), pp. 543-543 : 552-553

Amynthas minimus ( Horst, 1893)

Perichaeta minima: Horst 1893: 66 .

Pheretima minima: Gates 1972: 201 ; Ljungström 1972 a: 52; Reynolds & Cook 1976: 137.

Amynthas minimus: Zicsi & Reinecke 1992: 157 ; Reynolds 1993: 5; Zicsi 1998: 74; Dlamini 2002: 62; Blakemore 2004 b: 127, table 1; Horn et al. 2007: 175; Plisko 2010: 303.

Type locality: Indonesia, Java, Tijbodas .

Description:

External: Body length 20–40 mm, with width 1–2 mm. Number of segments 70–80.

Prostomium epilobous. Clitellum circular on 14–16. Spermathecal pores not observed.

Female pore minute on 14. Male pores paired on 18, on very raised but small porophores.

Genital markings not observed.

Internal: Septa 5/6, 6/7 and 7/8 moderately thickened, 8/9 and 9/10 missing. Gizzard in 8–10. Intestinal origin in 15. Caeca simple, originating in 27. Holandric. Spermathecae not observed. Seminal vesicles not observed. Prostates racemose, in 17–19.

Material examined: 203 cl.: Woodland, on road side near fence (29°34.810'S 30°19.271'E), 23.ii.2012, 37cl., NMSA /Olig.06104; 27 cl., NMSA /Olig.06182; Woodland, near Nursery (29°33.867'S 30°19.106'E), 3087ft, 23.ii.2012, 12 cl., NMSA /Olig.06105; 6 cl., NMSA /Olig.06183; Lawn, at the picnic site (29°34.091'S 30°19.276'E), 3040 ft, 24.ii.2012, 13 cl., NMSA /Olig06110; 4 cl., NMSA /Olig.06184; 13 cl., NMSA / Olig.06185; Indigenous Bush (29°34.357'S 30°19.399'E), 22.ii.2012, 21 cl., NMSA /Olig.06118; Indigenous Bush, big trees, soft moist soil (29°34.219'S 30°19.177'E), 3105 ft, 22.ii.2012, 6 cl., NMSA /Olig.06186; Indigenous Bush, big trees, wet soil, dense cover (29°34.151'S 30°19.263'E), 2996 ft, 22.ii.2012, 37 cl., NMSA /Olig.06188; Plantation, wattle & pine (29°33.655'S 30°18.919'E), 3106 ft, 23.ii.2012, 7 cl., NMSA / Olig.06125; 1 cl., NMSA /Olig.06187; 4 cl., NMSA /Olig.06189; 2 cl., NMSA /Olig.06190; 3 cl., NMSA / Olig.06191; Mixed Scrub, between plantation and grassland (29°33.683'S 30°18.992'E), 3149 ft, 24.ii.2012, 1 cl., NMSA /Olig.06192; 2 cl., NMSA /Olig.06183; 4 cl., NMSA /Olig.06129; Grassland, open patch of grass (29°34.123'S 30°19.153'E), 7.i.2012, 3 cl., NMSA /Olig.06140 .

Remarks: The large population of athecate specimens collected in QEP indicates parthenogenetic reproduction. Ljungström (1972 a) likewise collected parthenogenetic morphs with spermathecae and seminal vesicles reduced or absent, and also with an abnormally placed or shaped clitellum. However, thecate specimens have been recorded in this country as well (Plisko 2010; NMSAD). The species is known from various biotopes: grassland and meadows; and forested, natural and cultivated land ( Zicsi 1998; Plisko 2010).

It should be mentioned that thecate degeneration is a known phenomenon, attributed to parthenogenetic reproduction. Few species exhibiting it have been described ( Gates 1932, 1972; Tsai et al. 2002), although their systematic position has been discussed ( Blakemore 2003; Gates 1972; Sims & Easton 1972). Some of the species have been imprecisely accredited to a ‘species group’.