Parachilota wahlbergi ( Michaelsen, 1899 )

Plisko, J. D., 2008, New South African Acanthodrilinae earthworm species, with new data for some earlier known members of the genus Parachilota (Oligochaeta: Acanthodrilidae), African Invertebrates 49 (2), pp. 21-21 : 30-31

Parachilota wahlbergi ( Michaelsen, 1899)

Fig. 10

Chilota wahlbergi: Michaelsen 1899: 441 ; 1900: 147; 1912: 146.

Chilota wahlbergi f. typicus: Michaelsen 1913 a: 416.

Chilota wahlbergi n. f. pulchior Michaelsen, 1913 a: 416; Pickford 1937: 461.

Parachilota wahlbergi (Michaelsen) : Pickford 1937: 336.

Material examined: KwaZulu-Natal: NMSA /Olig.03650, 1 cl, farm Linwood [vicinity of Midmar Dam, 29°31'S: 30°11'E], in temporary pool during dry phase, under moist rock, 27.ix.2002, R. Pott .

Biological notes and distribution: Pickford (1937), who summarized collection data published by Michaelsen (1899, 1900, 1913 a) and the sites of the material studied by herself, accepted a broad occurrence of this species in north-eastern South Africa. It was known that the species was collected in moist or semi-moist localities, and in the neighbourhood of waterfalls, in KwaZulu-Natal, Gauteng, Mpumalanga and Limpopo. She also observed that some of the individuals from Krugersdorp area in Gauteng discharged a phosphorescent fluid. During my extended study on acanthodrilinae in South Africa, only one specimen of wahlbergi , the presently studied one, was collected in KZN in a small drying out artificial pool, in the neighbourhood of a man-made lake where environmental changes are taking place. It is possible that this species may be on the way to extinction as a result of anthropogenic environmental changes. The studied specimen was donated alive to the Natal Museum, and no phosphorescence was observed before and during preservation.

Comments: The new material matches descriptions of the type material ( Michaelsen 1899, 1900) extended by additional data by Michaelsen (1913 a) and Pickford (1937). Pickford (1937), concluding that in this species the degree of pigmentation is not a satisfactory taxonomic feature, noted body colouration fading after a few years of preservation and accounted Michaelsen’s distinction of wahlbergi f. pulchior on the base of pigmentation not valid, and synonomised it with f. typicus. The currently examined specimen was violet pigmented dorsally in life, this colour extending to the middle of the body, and kept its tint for a short time in alcohol before the colour faded. The spermathecal ampulla is oval, slightly enlarged at its ental part. The diverticulum ( Fig. 10 ) is unilobate, tubular, almost twice as long as ampulla. The anterior pair of the prostatic glands stretches through four segments, the posterior pair extending backwards through five segments. No penial setae were observed in the studied specimen.

BILOBATE species-group

Parachilota editha ( Pickford, 1927)

Chilota editha: Pickford 1927: 452 .

Parachilota editha (Pickford) : Pickford 1937: 330; Zicsi 1998: 66.

Material studied: KwaZulu-Natal: NMSA / Olig.01874, 2 cl, Drakensberg, Giant Castle (29°20'S: 29°27'E), Protea field, grassland, 9.iii.1993, JDP & BRS .

Biological notes and distribution: The species was described from a single specimen from the Eastern Cape, found in the graveyard area in the neighbourhood of Stutterheim [32°32'S: 27°29'E], and Pickford suspected its accidental transportation from the Drakensberg foothills. Zicsi (1998) reported this species from the Karkloof Nat. Res. (29°18'S: 30°13'E) in KZN. The present record from Giant’s Castle supports Pickford’s supposition that the species occurs in a broader area of the Drakensberg Mountains .

Comments: The new material matches the species description ( Pickford 1927) and its re-description (Pickford 1937). However, on the drawing made by Pickford (1937: fig. 279) a diverticulum is presented as one lobe extended over the spermathecal duct, with no middle division. In currently studied material the spermathecal diverticulum is bilobate, with a groove in the middle of the diverticulum face, a character not previously noted. The ornamentation of the penial setae indicated in the re-description (Pickford 1937) was not observed in new material.

Figures

Figs 6–10. Parachilota species with unilobate diverticulum: (6–9) P. timothyi sp. n., holotype: (6) anterior part of body, ventrally, 40×; (7) spermathecae of segment 8 and 9, 400×: (8) prostates of 17 and 19, 370×; (9) genital setae of 17 (a seta, 9A) and 19 (b seta, 9B), 500×; (10) P. wahlbergi (Michaelsen, 1899), spermathecae, 500×. Abbreviations: A – ampulla, Cl – clitellum, D – spermathecal duct, Pd – prostatic duct, Pg – prostatic gland, PR – prostatic pores of 17 and 19, Udv – unilobate diverticulum.