Dichogaster (Dichogaster) thomeana Cognetti, 1910

Csuzdi, Csaba, 2005, Earthworms (Annelida: Oligochaeta) of Sao Tomé, Journal of Natural History 39 (33), pp. 3039-3058 : 3041-3042

Dichogaster (Dichogaster) thomeana Cognetti, 1910

( Figures 4–6 )

Dichogaster thomeana Cognetti 1910, p 100 .

Dichogaster (Dichogaster) greeffi: Csuzdi 1995, p 109 , part.

Dichogaster (Dichogaster) greeffi: Csuzdi 2000, p 55 .

Material examined

AF/5003 four ex. Sao Tome´, on the volcano around Lago Amélia, 1450 m asl, from fallen logs, leg. Cs. Csuzdi, 30 August 2000.

Diagnosis

L. 55–60 mm, D. 2.5–3 mm, number of segments 117–126. Colour alive purplish brown, conserved pale. First dorsal pore in 12/13. Clitellum 13–20, prostatic pores in segment 17, 19, spermathecal pores in 7/8, 8/9 ( Figure 4 ). Spermatheca ampulla barbell-shaped, duct long muscular, diverticula empty, unilocular with long duct ( Figure 5 ). Calciferous glands three pairs in 15–17, the first pair is slightly smaller than the others. Meronephridia four to five on each side of the intestine. Penial setae uniform, the fully adult seta 1.7–1.8 mm long and in the middle 0.04 mm wide. The seta is slightly curved and the spoon-shaped tip is reclinate. Each seta bears a characteristic ornamentation which are large serrated sculptures on the ental part becoming large thorns towards the ectal part ( Figure 6 ).

Remarks

This species was synonymized with D. (D.) greeffi by Csuzdi (1995) on the basis of the original description of the three juvenile specimens of D. (D.) thomeana and on examination of the type material of D. (D.) greeffi housed in the Michaelsen collection, Hamburg. The slight differences in the spermathecae and penial setae were attributed to the juvenile stage of Cognetti’s specimens. SEM study of the penial seta of the new material revealed that its tip is spoon-shaped and reclinate which is markedly different from the sharply hooked seta of D. (D.) greeffi . Relying upon this observation I conclude that the two names refer to completely different species and D. (D.) thomeana should be removed from synonymy.

Figures

Figure 4. D. (D.) thomeana, ventral side of the clitellum.

Figure 5. D. (D.) thomeana, spermatheca.

Figure 6. D. (D.) thomeana, penial seta: (a) whole seta; (b) middle part of the seta with the characteristic ornamentation; (c) tip of the seta.