Dichogaster (Diplothecodrilus) zicsii, Csuzdi, 2005

Csuzdi, Csaba, 2005, Earthworms (Annelida: Oligochaeta) of Sao Tomé, Journal of Natural History 39 (33), pp. 3039-3058 : 3046-3048

Dichogaster (Diplothecodrilus) zicsii sp. nov.

( Figures 9–11 )

Material examined

Holotype: AF/5057 Sao Tome´, Monte Cafe´, near to the waterfall, 860 m asl, in fallen logs, leg. Cs. Csuzdi, 26 August 2000. Paratypes: AF/5058 six ex. Locality same as that of the holotype.

Derivatio nominis

The new species is named in honour of my mentor, Prof. Dr András Zicsi, the recognized earthworm taxonomist.

Diagnosis

L. 18–27 mm, D. 1.2–2 mm, number of segments 88–103. Colour purple on dorsal and pale on ventral. First dorsal pore in 6/7 closed. Clitellum 13–20, prostatic pores 17, 19, spermathecal pores 7/8, 8/9. Spermathecae elongated skittle-shaped, with long duct and bifid diverticula. Penial setae are of two types, larger about 0.4 mm long and 0.008 mm wide with spatula-like tip, smaller about 0.3 mm long and 0.006 mm wide with a sharply pointed tip.

External characters

Holotype: L. 22 mm, D. 1.5 mm, number of segments 98. Paratypes: L. 18–27 mm, D. 1.2– 2 mm, number of segments 88–103. Colour pale, anterodorsally with purple pigments. Prostomium pro-epilobous with a small line cutting through the first segment. First dorsal pore in 6/7 closed. Setae all ventral, setal arrangement after the clitellum aa:ab:bc:cd:dd5 11:3:10:2.5:60. Clitellum extends over segments 13–20, annular with a barbell-shaped male field. Prostatic pores paired on 17, 19 in the setal line b. Male pores externally not visible, they are on 18, deep in the seminal groves. Female pores paired on 14 near to the setae a-a ( Figure 9 ). Spermathecal pores paired in 7/8, 8/9 near to the setae b. Porophores absent.

Internal characters

No septa notably thickened. Oesophageal gizzards two, in segments 5 and 6. The three pairs of calciferous glands are of about equal size, located in segments 15–17. Excretory system meronephridial, with two to three meronephridia on each side. Paired hearts are present in segments 10, 11, and 12.

Testes are paired in 10 and 11 enclosed into free sperm mass filling the cavity of the segments. Seminal vesicles lacking, ovary small in segment 13. Seminal duct convoluted, discharging through a small muscular atrium in segment 18. Two pairs of small prostatic glands are present in 17 and 19, confined into their own segment and each provided with a penial setal sack containing two different types of penial setae. The larger one is about 0.4 mm long and 0.008 mm wide with spatula-like tip and minute serrated ornamentation. The smaller one is smooth, about 0.3 mm long and 0.006 mm wide with sharply pointed tip ( Figure 10 ). There are two pairs of spermathecae in segments 8 and 9. Each has an elongated skittle-shaped ampulla and an equally long duct. The lower part of the ampulla bears a small, sometimes bifid diverticulum ( Figure 11 ).

Remarks

Dichogaster (Diplothecodrilus) zicsii , bearing two types of penial setae, belongs to the bolaui species group ( Csuzdi 1996) and shows affinities with D. (Dt.) bolaui ( Michaelsen, 1891) and D. (Dt.) amphibiotica Dahl, 1957 but differs from both species in the paired female pores, in the shape and ornamentation of the penial setae and furthermore in the presence of a muscular thickening at the end of the male duct.

Figures

Figure 9. D. (Dt.) zicsii sp. nov., ventral side of the clitellum.

Figure 10. D. (Dt.) zicsii sp. nov., penial setae: (a) whole setae; (b) tip of the setae; (c) ornamentation of the larger seta.

Figure 11. D. (Dt.) zicsii sp. nov., spermatheca.