Dichogaster (Diplothecodrilus) silvestris ( Michaelsen, 1896 )

Csuzdi, Csaba, 2008, Earthworms from the Kivu Region, D. R. Congo with description of two new Dichogaster Beddard, 1888 (Oligochaeta: Acanthodrilidae, Ocnerodrilidae), Journal of Natural History 42 (33 - 34), pp. 2227-2241 : 2235-2236

Dichogaster (Diplothecodrilus) silvestris ( Michaelsen, 1896)

( Figure 5A–D )

Benhamia silvestris Michaelsen 1896, p. 24 .

Dichogaster silvestris: Michaelsen 1900, p. 352 , Michaelsen 1905, p. 310. Dichogaster seriatospina Michaelsen 1912, p. 30 syn. nov.

Dichogaster anguana Michaelsen 1915, p. 209 syn. nov.

Dichogaster (Diplothecodrilus) seriatospina: Csuzdi 1995, p. 114 , Csuzdi 1996, p. 357. Dichogaster (Diplothecodrilus) anguana: Csuzdi 1995, p. 112 , Csuzdi 1996, p. 357. Dichogaster (Diplothecodrilus) silvestris: Csuzdi 1995, p. 114 , Csuzdi 1996, p. 357, Csuzdi 2000, p. 67.

Material examined

Dichogaster silvestris Holotype, ZMUH V295 , D.-O. Afrika, Ru-nsosro, leg. Stuhlmann.

New records. HNHM 3537 , four exemplars , BMNH 1997.1468 – 1474 , seven exemplars , BMNH 1997.1524 – 1525 , two exemplars. D . R. Congo, Kivu Region , Ngungu, leg. Gasana N’Doli, 16 July 1973 , HNHM 3547 , one exemplar , BMNH 1997.1509 – 1511 , three exemplars. D . R. Congo, Kivu Region , Katana, in stems of banana trees, leg. Gasana N’Doli, 5 August 1973 . HNHM AF/3552, two exemplars, BMNH 1997.1648 – 1650 , three exemplars. D . R. Congo, Kivu Region , Idjiri island, leg. Gasana N’Doli, 2 July 1973 . HNHM AF/3559, one exemplar, BMNH 1997.1677 – 1678 , two exemplars. D . R. Congo, Kivu Region , Lwiro, leg. Gasana N’Doli, 19 January 1973 . HNHM AF/3563, three exemplars, BMNH 1997.1493 – 1498 , six exemplars. D . R. Congo, Kivu Region , Ngungu, in the swamp, leg. Gasana N’Doli, 16 July 1973 . HNHM AF/3567, 10 exemplars, BMNH 1997.1652 – 1661 , ten exemplars. D . R. Congo, Kivu Region , Lwiro, leg. Gasana N’Doli, 16 February 1973 .

Diagnosis

Length 35–60 mm, D. 3–4 mm, no. of segments 85–112. Pigmentation brownish. First dorsal pore in 5/6. Clitellum 13–20, K 21, 21. ♀ 14 paired between setae a–a. Prostatic pores 17, 19, genital field oblong with rounded edges. Spermathecal pores 7/8, 8/9, ampoule of the spermatheca bulb-shaped with small distal part bearing a round and stalked diverticulum. The duct is slightly convoluted and much longer than the ampoule. Gizzard in 5/6, last pair of hearts in 12. Calciferous glands in 15–17 of equal size. Excretory system meroic with six meronephridia per side. Penial seta L. 4–5 mm, D. 0.02 mm, ectal third undulated, tip hook-shaped, ornamentation fine teeth.

Remarks

This species was described on a pre-adult specimen with not fully developed clitellum on segment 13–19. Dichogaster (Dt.) seriatospina Michaelsen, 1912 differs from D. (Dt.) silvestris only in the position of the clitellum therefore it must be regarded as a synonym of D. (Dt.) silvestris . Dichogaster anguana Michaelsen, 1915 was also described on a juvenile specimen; however, its spermathecae and the structure of the penial setae are identical to those of D. (Dt.) silvestris . It differs only in the length of the penial setae, which is because of the juvenile stage of the type specimen, therefore D. (Dt.) anguana is also a synonym of D. (Dt.) silvestris .

Figures

Figure 5. Dichogaster (Dt.) silvestris. (A) Ventral part of the clitellar region; (B) penial seta; (C) ornamentation of the penial seta; (D) spermatheca. St, spermathecal pores; Pr, prostate pores.